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https://github.com/fish-shell/fish-shell
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85d4834b35
Closes #9240. Squash of the following commits (in reverse-chronological order): commit 03b5cab3dc40eca9d50a9df07a8a32524338a807 Author: Mahmoud Al-Qudsi <mqudsi@neosmart.net> Date: Sun Sep 25 15:09:04 2022 -0500 Handle differently declared posix_spawnxxx_t on macOS On macOS, posix_spawnattr_t and posix_spawn_file_actions_t are declared as void pointers, so we can't use maybe_t's bool operator to test if it has a value. commit aed83b8bb308120c0f287814d108b5914593630a Author: Mahmoud Al-Qudsi <mqudsi@neosmart.net> Date: Sun Sep 25 14:48:46 2022 -0500 Update maybe_t tests to reflect dynamic bool conversion maybe_t<T> is now bool-convertible only if T _isn't_ already bool-convertible. commit 2b5a12ca97b46f96b1c6b56a41aafcbdb0dfddd6 Author: Mahmoud Al-Qudsi <mqudsi@neosmart.net> Date: Sun Sep 25 14:34:03 2022 -0500 Make maybe_t a little harder to misuse We've had a few bugs over the years stemming from accidental misuse of maybe_t with bool-convertible types. This patch disables maybe_t's bool operator if the type T is already bool convertible, forcing the (barely worth mentioning) need to use maybe_t::has_value() instead. This patch both removes maybe_t's bool conversion for bool-convertible types and updates the existing codebase to use the explicit `has_value()` method in place of existing implicit bool conversions.
1251 lines
51 KiB
C++
1251 lines
51 KiB
C++
// Functions for executing a program.
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//
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// Some of the code in this file is based on code from the Glibc manual, though the changes
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// performed have been massive.
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#include "config.h"
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#include <ctype.h>
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#include <errno.h>
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#include <fcntl.h>
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#ifdef HAVE_SIGINFO_H
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#include <siginfo.h>
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#endif
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#include <paths.h>
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#include <stdio.h>
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#include <unistd.h>
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#include <algorithm>
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#include <cstdint>
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#include <cstdlib>
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#include <cstring>
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#include <functional>
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#include <initializer_list>
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#include <map>
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#include <memory>
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#include <string>
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#include <utility>
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#include <vector>
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#include "ast.h"
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#include "builtin.h"
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#include "common.h"
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#include "env.h"
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#include "exec.h"
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#include "fallback.h" // IWYU pragma: keep
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#include "fds.h"
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#include "flog.h"
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#include "function.h"
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#include "global_safety.h"
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#include "io.h"
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#include "iothread.h"
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#include "job_group.h"
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#include "maybe.h"
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#include "null_terminated_array.h"
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#include "parse_tree.h"
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#include "parser.h"
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#include "postfork.h"
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#include "proc.h"
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#include "reader.h"
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#include "redirection.h"
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#include "timer.h"
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#include "trace.h"
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#include "wait_handle.h"
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#include "wcstringutil.h"
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#include "wutil.h" // IWYU pragma: keep
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/// Number of calls to fork() or posix_spawn().
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static relaxed_atomic_t<int> s_fork_count{0};
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/// A launch_result_t indicates when a process failed to launch, and therefore the rest of the
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/// pipeline should be aborted. This includes failed redirections, fd exhaustion, fork() failures,
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/// etc.
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enum class launch_result_t {
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ok,
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failed,
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} __warn_unused_type;
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/// Given an error \p err returned from either posix_spawn or exec, \return a process exit code.
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static int exit_code_from_exec_error(int err) {
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assert(err && "Zero is success, not an error");
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switch (err) {
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case ENOENT:
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case ENOTDIR:
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// This indicates either the command was not found, or a file redirection was not found.
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// We do not use posix_spawn file redirections so this is always command-not-found.
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return STATUS_CMD_UNKNOWN;
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case EACCES:
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case ENOEXEC:
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// The file is not executable for various reasons.
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return STATUS_NOT_EXECUTABLE;
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#ifdef EBADARCH
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case EBADARCH:
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// This is for e.g. running ARM app on Intel Mac.
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return STATUS_NOT_EXECUTABLE;
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#endif
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default:
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// Generic failure.
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return EXIT_FAILURE;
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}
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}
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/// This is a 'looks like text' check.
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/// \return true if either there is no NUL byte, or there is a line containing a lowercase letter
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/// before the first NUL byte.
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static bool is_thompson_shell_payload(const char *p, size_t n) {
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if (!memchr(p, '\0', n)) return true;
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bool haslower = false;
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for (; *p; p++) {
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if (islower(*p) || *p == '$' || *p == '`') {
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haslower = true;
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}
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if (haslower && *p == '\n') {
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return true;
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}
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}
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return false;
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}
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/// This function checks the beginning of a file to see if it's safe to
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/// pass to the system interpreter when execve() returns ENOEXEC.
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///
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/// The motivation is to be able to run classic shell scripts which
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/// didn't have shebang, while protecting the user from accidentally
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/// running a binary file which may corrupt terminal driver state. We
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/// check for lowercase letters because the ASCII magic of binary files
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/// is usually uppercase, e.g. PNG, JFIF, MZ, etc. These rules are also
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/// flexible enough to permit scripts with concatenated binary content,
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/// such as Actually Portable Executable.
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/// N.B.: this is called after fork, it must not allocate heap memory.
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bool is_thompson_shell_script(const char *path) {
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// Paths ending in ".fish" are never considered Thompson shell scripts.
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if (const char *lastdot = strrchr(path, '.')) {
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if (0 == strcmp(lastdot, ".fish")) {
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return false;
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}
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}
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int e = errno;
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bool res = false;
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int fd = open_cloexec(path, O_RDONLY | O_NOCTTY);
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if (fd != -1) {
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char buf[256];
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ssize_t got = read(fd, buf, sizeof(buf));
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close(fd);
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if (got >= 0 && is_thompson_shell_payload(buf, static_cast<size_t>(got))) {
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res = true;
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}
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}
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errno = e;
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return res;
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}
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/// This function is executed by the child process created by a call to fork(). It should be called
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/// after \c child_setup_process. It calls execve to replace the fish process image with the command
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/// specified in \c p. It never returns. Called in a forked child! Do not allocate memory, etc.
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[[noreturn]] static void safe_launch_process(process_t *p, const char *actual_cmd,
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const char *const *cargv, const char *const *cenvv) {
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UNUSED(p);
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int err;
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// This function never returns, so we take certain liberties with constness.
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auto envv = const_cast<char **>(cenvv);
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auto argv = const_cast<char **>(cargv);
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auto cmd2 = const_cast<char *>(actual_cmd);
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execve(actual_cmd, argv, envv);
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err = errno;
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// The shebang wasn't introduced until UNIX Seventh Edition, so if
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// the kernel won't run the binary we hand it off to the interpreter
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// after performing a binary safety check, recommended by POSIX: a
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// line needs to exist before the first \0 with a lowercase letter
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if (err == ENOEXEC && is_thompson_shell_script(actual_cmd)) {
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// Construct new argv.
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// We must not allocate memory, so only 128 args are supported.
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constexpr size_t maxargs = 128;
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size_t nargs = 0;
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while (argv[nargs]) nargs++;
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if (nargs <= maxargs) {
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char *argv2[1 + maxargs + 1]; // +1 for /bin/sh, +1 for terminating nullptr
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char interp[] = _PATH_BSHELL;
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argv2[0] = interp;
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std::copy_n(argv, 1 + nargs, &argv2[1]); // +1 to copy terminating nullptr
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// The command to call should use the full path,
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// not what we would pass as argv0.
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argv2[1] = cmd2;
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execve(_PATH_BSHELL, argv2, envv);
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}
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}
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errno = err;
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safe_report_exec_error(errno, actual_cmd, argv, envv);
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exit_without_destructors(exit_code_from_exec_error(err));
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}
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/// This function is similar to launch_process, except it is not called after a fork (i.e. it only
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/// calls exec) and therefore it can allocate memory.
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[[noreturn]] static void launch_process_nofork(env_stack_t &vars, process_t *p) {
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ASSERT_IS_NOT_FORKED_CHILD();
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// Construct argv. Ensure the strings stay alive for the duration of this function.
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std::vector<std::string> narrow_strings = wide_string_list_to_narrow(p->argv());
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null_terminated_array_t<char> narrow_argv(narrow_strings);
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const char **argv = narrow_argv.get();
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// Construct envp.
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auto export_vars = vars.export_arr();
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const char **envp = export_vars->get();
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std::string actual_cmd = wcs2string(p->actual_cmd);
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// Ensure the terminal modes are what they were before we changed them.
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restore_term_mode();
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// Bounce to launch_process. This never returns.
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safe_launch_process(p, actual_cmd.c_str(), argv, envp);
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}
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// Returns whether we can use posix spawn for a given process in a given job.
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//
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// To avoid the race between the caller calling tcsetpgrp() and the client checking the
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// foreground process group, we don't use posix_spawn if we're going to foreground the process. (If
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// we use fork(), we can call tcsetpgrp after the fork, before the exec, and avoid the race).
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static bool can_use_posix_spawn_for_job(const std::shared_ptr<job_t> &job,
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const dup2_list_t &dup2s) {
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// Is it globally disabled?
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if (!get_use_posix_spawn()) return false;
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// Hack - do not use posix_spawn if there are self-fd redirections.
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// For example if you were to write:
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// cmd 6< /dev/null
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// it is possible that the open() of /dev/null would result in fd 6. Here even if we attempted
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// to add a dup2 action, it would be ignored and the CLO_EXEC bit would remain. So don't use
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// posix_spawn in this case; instead we'll call fork() and clear the CLO_EXEC bit manually.
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for (const auto &action : dup2s.get_actions()) {
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if (action.src == action.target) return false;
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}
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if (job->group->wants_terminal()) {
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// This job will be foregrounded, so we will call tcsetpgrp(), therefore do not use
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// posix_spawn.
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return false;
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}
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return true;
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}
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static void internal_exec(env_stack_t &vars, job_t *j, const io_chain_t &block_io) {
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// Do a regular launch - but without forking first...
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process_t *p = j->processes.front().get();
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io_chain_t all_ios = block_io;
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if (!all_ios.append_from_specs(p->redirection_specs(), vars.get_pwd_slash())) {
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return;
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}
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// child_setup_process makes sure signals are properly set up.
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dup2_list_t redirs = dup2_list_t::resolve_chain(all_ios);
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if (child_setup_process(false /* not claim_tty */, *j, false /* not is_forked */, redirs) ==
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0) {
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// Decrement SHLVL as we're removing ourselves from the shell "stack".
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if (is_interactive_session()) {
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auto shlvl_var = vars.get(L"SHLVL", ENV_GLOBAL | ENV_EXPORT);
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wcstring shlvl_str = L"0";
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if (shlvl_var) {
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long shlvl = fish_wcstol(shlvl_var->as_string().c_str());
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if (!errno && shlvl > 0) {
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shlvl_str = to_string(shlvl - 1);
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}
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}
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vars.set_one(L"SHLVL", ENV_GLOBAL | ENV_EXPORT, std::move(shlvl_str));
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}
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// launch_process _never_ returns.
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launch_process_nofork(vars, p);
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}
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}
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/// Construct an internal process for the process p. In the background, write the data \p outdata to
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/// stdout and \p errdata to stderr, respecting the io chain \p ios. For example if target_fd is 1
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/// (stdout), and there is a dup2 3->1, then we need to write to fd 3. Then exit the internal
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/// process.
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static void run_internal_process(process_t *p, std::string &&outdata, std::string &&errdata,
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const io_chain_t &ios) {
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p->check_generations_before_launch();
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// We want both the dup2s and the io_chain_ts to be kept alive by the background thread, because
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// they may own an fd that we want to write to. Move them all to a shared_ptr. The strings as
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// well (they may be long).
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// Construct a little helper struct to make it simpler to move into our closure without copying.
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struct write_fields_t {
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int src_outfd{-1};
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std::string outdata{};
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int src_errfd{-1};
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std::string errdata{};
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io_chain_t ios{};
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maybe_t<dup2_list_t> dup2s{};
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std::shared_ptr<internal_proc_t> internal_proc{};
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proc_status_t success_status{};
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bool skip_out() const { return outdata.empty() || src_outfd < 0; }
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bool skip_err() const { return errdata.empty() || src_errfd < 0; }
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};
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auto f = std::make_shared<write_fields_t>();
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f->outdata = std::move(outdata);
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f->errdata = std::move(errdata);
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// Construct and assign the internal process to the real process.
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p->internal_proc_ = std::make_shared<internal_proc_t>();
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f->internal_proc = p->internal_proc_;
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FLOGF(proc_internal_proc, L"Created internal proc %llu to write output for proc '%ls'",
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p->internal_proc_->get_id(), p->argv0());
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// Resolve the IO chain.
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// Note it's important we do this even if we have no out or err data, because we may have been
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// asked to truncate a file (e.g. `echo -n '' > /tmp/truncateme.txt'). The open() in the dup2
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// list resolution will ensure this happens.
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f->dup2s = dup2_list_t::resolve_chain(ios);
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// Figure out which source fds to write to. If they are closed (unlikely) we just exit
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// successfully.
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f->src_outfd = f->dup2s->fd_for_target_fd(STDOUT_FILENO);
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f->src_errfd = f->dup2s->fd_for_target_fd(STDERR_FILENO);
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// If we have nothing to write we can elide the thread.
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// TODO: support eliding output to /dev/null.
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if (f->skip_out() && f->skip_err()) {
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f->internal_proc->mark_exited(p->status);
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return;
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}
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// Ensure that ios stays alive, it may own fds.
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f->ios = ios;
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// If our process is a builtin, it will have already set its status value. Make sure we
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// propagate that if our I/O succeeds and don't read it on a background thread. TODO: have
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// builtin_run provide this directly, rather than setting it in the process.
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f->success_status = p->status;
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iothread_perform_cantwait([f]() {
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proc_status_t status = f->success_status;
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if (!f->skip_out()) {
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ssize_t ret = write_loop(f->src_outfd, f->outdata.data(), f->outdata.size());
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if (ret < 0) {
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if (errno != EPIPE) {
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wperror(L"write");
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}
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if (status.is_success()) {
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status = proc_status_t::from_exit_code(1);
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}
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}
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}
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if (!f->skip_err()) {
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ssize_t ret = write_loop(f->src_errfd, f->errdata.data(), f->errdata.size());
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if (ret < 0) {
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if (errno != EPIPE) {
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wperror(L"write");
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}
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if (status.is_success()) {
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status = proc_status_t::from_exit_code(1);
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}
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}
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}
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f->internal_proc->mark_exited(status);
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});
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}
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/// If \p outdata or \p errdata are both empty, then mark the process as completed immediately.
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/// Otherwise, run an internal process.
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static void run_internal_process_or_short_circuit(parser_t &parser, const std::shared_ptr<job_t> &j,
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process_t *p, std::string &&outdata,
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std::string &&errdata, const io_chain_t &ios) {
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if (outdata.empty() && errdata.empty()) {
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p->completed = true;
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if (p->is_last_in_job) {
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FLOGF(exec_job_status, L"Set status of job %d (%ls) to %d using short circuit",
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j->job_id(), j->preview().c_str(), p->status);
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auto statuses = j->get_statuses();
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if (statuses) {
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parser.set_last_statuses(statuses.value());
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parser.libdata().status_count++;
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} else if (j->flags().negate) {
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// Special handling for `not set var (substitution)`.
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// If there is no status, but negation was requested,
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// take the last status and negate it.
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auto last_statuses = parser.get_last_statuses();
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last_statuses.status = !last_statuses.status;
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parser.set_last_statuses(last_statuses);
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}
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}
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} else {
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run_internal_process(p, std::move(outdata), std::move(errdata), ios);
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}
|
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}
|
||
|
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bool blocked_signals_for_job(const job_t &job, sigset_t *sigmask) {
|
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// Block some signals in background jobs for which job control is turned off (#6828).
|
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if (!job.is_foreground() && !job.wants_job_control()) {
|
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sigaddset(sigmask, SIGINT);
|
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sigaddset(sigmask, SIGQUIT);
|
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return true;
|
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}
|
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return false;
|
||
}
|
||
|
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/// Call fork() as part of executing a process \p p in a job \j. Execute \p child_action in the
|
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/// context of the child.
|
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static launch_result_t fork_child_for_process(const std::shared_ptr<job_t> &job, process_t *p,
|
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const dup2_list_t &dup2s, const char *fork_type,
|
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const std::function<void()> &child_action) {
|
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// Claim the tty from fish, if the job wants it and we are the pgroup leader.
|
||
pid_t claim_tty_from =
|
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(p->leads_pgrp && job->group->wants_terminal()) ? getpgrp() : INVALID_PID;
|
||
|
||
pid_t pid = execute_fork();
|
||
if (pid < 0) {
|
||
return launch_result_t::failed;
|
||
}
|
||
const bool is_parent = (pid > 0);
|
||
|
||
// Record the pgroup if this is the leader.
|
||
// Both parent and child attempt to send the process to its new group, to resolve the race.
|
||
p->pid = is_parent ? pid : getpid();
|
||
if (p->leads_pgrp) {
|
||
job->group->set_pgid(p->pid);
|
||
}
|
||
{
|
||
auto pgid = job->group->get_pgid();
|
||
if (pgid.has_value()) {
|
||
if (int err = execute_setpgid(p->pid, *pgid, is_parent)) {
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report_setpgid_error(err, is_parent, *pgid, job.get(), p);
|
||
}
|
||
}
|
||
}
|
||
|
||
if (!is_parent) {
|
||
// Child process.
|
||
child_setup_process(claim_tty_from, *job, true, dup2s);
|
||
child_action();
|
||
DIE("Child process returned control to fork_child lambda!");
|
||
}
|
||
|
||
++s_fork_count;
|
||
FLOGF(exec_fork, L"Fork #%d, pid %d: %s for '%ls'", int(s_fork_count), pid, fork_type,
|
||
p->argv0());
|
||
return launch_result_t::ok;
|
||
}
|
||
|
||
/// \return an newly allocated output stream for the given fd, which is typically stdout or stderr.
|
||
/// This inspects the io_chain and decides what sort of output stream to return.
|
||
/// If \p piped_output_needs_buffering is set, and if the output is going to a pipe, then the other
|
||
/// end then synchronously writing to the pipe risks deadlock, so we must buffer it.
|
||
static std::shared_ptr<output_stream_t> create_output_stream_for_builtin(
|
||
int fd, const io_chain_t &io_chain, bool piped_output_needs_buffering) {
|
||
using std::make_shared;
|
||
const shared_ptr<const io_data_t> io = io_chain.io_for_fd(fd);
|
||
if (io == nullptr) {
|
||
// Common case of no redirections.
|
||
// Just write to the fd directly.
|
||
return make_shared<fd_output_stream_t>(fd);
|
||
}
|
||
switch (io->io_mode) {
|
||
case io_mode_t::bufferfill: {
|
||
// Our IO redirection is to an internal buffer, e.g. a command substitution.
|
||
// We will write directly to it.
|
||
std::shared_ptr<io_buffer_t> buffer =
|
||
std::static_pointer_cast<const io_bufferfill_t>(io)->buffer();
|
||
return make_unique<buffered_output_stream_t>(buffer);
|
||
}
|
||
|
||
case io_mode_t::close:
|
||
// Like 'echo foo >&-'
|
||
return make_shared<null_output_stream_t>();
|
||
|
||
case io_mode_t::file:
|
||
// Output is to a file which has been opened.
|
||
return make_shared<fd_output_stream_t>(io->source_fd);
|
||
|
||
case io_mode_t::pipe:
|
||
// Output is to a pipe. We may need to buffer.
|
||
if (piped_output_needs_buffering) {
|
||
return make_shared<string_output_stream_t>();
|
||
} else {
|
||
return make_shared<fd_output_stream_t>(io->source_fd);
|
||
}
|
||
|
||
case io_mode_t::fd:
|
||
// This is a case like 'echo foo >&5'
|
||
// It's uncommon and unclear what should happen.
|
||
return make_shared<string_output_stream_t>();
|
||
}
|
||
DIE("Unreachable");
|
||
}
|
||
|
||
/// Handle output from a builtin, by printing the contents of builtin_io_streams to the redirections
|
||
/// given in io_chain.
|
||
static void handle_builtin_output(parser_t &parser, const std::shared_ptr<job_t> &j, process_t *p,
|
||
const io_chain_t &io_chain, const output_stream_t &out,
|
||
const output_stream_t &err) {
|
||
assert(p->type == process_type_t::builtin && "Process is not a builtin");
|
||
|
||
// Figure out any data remaining to write. We may have none, in which case we can short-circuit.
|
||
std::string outbuff = wcs2string(out.contents());
|
||
std::string errbuff = wcs2string(err.contents());
|
||
|
||
// Some historical behavior.
|
||
if (!outbuff.empty()) fflush(stdout);
|
||
if (!errbuff.empty()) fflush(stderr);
|
||
|
||
// Construct and run our background process.
|
||
run_internal_process_or_short_circuit(parser, j, p, std::move(outbuff), std::move(errbuff),
|
||
io_chain);
|
||
}
|
||
|
||
/// Executes an external command.
|
||
/// An error return here indicates that the process failed to launch, and the rest of
|
||
/// the pipeline should be cancelled.
|
||
static launch_result_t exec_external_command(parser_t &parser, const std::shared_ptr<job_t> &j,
|
||
process_t *p, const io_chain_t &proc_io_chain) {
|
||
assert(p->type == process_type_t::external && "Process is not external");
|
||
// Get argv and envv before we fork.
|
||
const std::vector<std::string> narrow_argv = wide_string_list_to_narrow(p->argv());
|
||
null_terminated_array_t<char> argv_array(narrow_argv);
|
||
|
||
// Convert our IO chain to a dup2 sequence.
|
||
auto dup2s = dup2_list_t::resolve_chain(proc_io_chain);
|
||
|
||
// Ensure that stdin is blocking before we hand it off (see issue #176).
|
||
// Note this will also affect stdout and stderr if they refer to the same tty.
|
||
make_fd_blocking(STDIN_FILENO);
|
||
|
||
auto export_arr = parser.vars().export_arr();
|
||
const char *const *argv = argv_array.get();
|
||
const char *const *envv = export_arr->get();
|
||
|
||
std::string actual_cmd_str = wcs2string(p->actual_cmd);
|
||
const char *actual_cmd = actual_cmd_str.c_str();
|
||
filename_ref_t file = parser.libdata().current_filename;
|
||
|
||
#if FISH_USE_POSIX_SPAWN
|
||
// Prefer to use posix_spawn, since it's faster on some systems like OS X.
|
||
if (can_use_posix_spawn_for_job(j, dup2s)) {
|
||
++s_fork_count; // spawn counts as a fork+exec
|
||
|
||
posix_spawner_t spawner(j.get(), dup2s);
|
||
maybe_t<pid_t> pid = spawner.spawn(actual_cmd, const_cast<char *const *>(argv),
|
||
const_cast<char *const *>(envv));
|
||
if (int err = spawner.get_error()) {
|
||
safe_report_exec_error(err, actual_cmd, argv, envv);
|
||
p->status = proc_status_t::from_exit_code(exit_code_from_exec_error(err));
|
||
return launch_result_t::failed;
|
||
}
|
||
assert(pid.has_value() && *pid > 0 && "Should have either a valid pid, or an error");
|
||
|
||
// This usleep can be used to test for various race conditions
|
||
// (https://github.com/fish-shell/fish-shell/issues/360).
|
||
// usleep(10000);
|
||
|
||
FLOGF(exec_fork, L"Fork #%d, pid %d: spawn external command '%s' from '%ls'",
|
||
int(s_fork_count), *pid, actual_cmd, file ? file->c_str() : L"<no file>");
|
||
|
||
// these are all things do_fork() takes care of normally (for forked processes):
|
||
p->pid = *pid;
|
||
if (p->leads_pgrp) {
|
||
j->group->set_pgid(p->pid);
|
||
// posix_spawn should in principle set the pgid before returning.
|
||
// In glibc, posix_spawn uses fork() and the pgid group is set on the child side;
|
||
// therefore the parent may not have seen it be set yet.
|
||
// Ensure it gets set. See #4715, also https://github.com/Microsoft/WSL/issues/2997.
|
||
execute_setpgid(p->pid, p->pid, true /* is parent */);
|
||
}
|
||
return launch_result_t::ok;
|
||
} else
|
||
#endif
|
||
{
|
||
return fork_child_for_process(j, p, dup2s, "external command",
|
||
[&] { safe_launch_process(p, actual_cmd, argv, envv); });
|
||
}
|
||
}
|
||
|
||
// Given that we are about to execute a function, push a function block and set up the
|
||
// variable environment.
|
||
static block_t *function_prepare_environment(parser_t &parser, wcstring_list_t argv,
|
||
const function_properties_t &props) {
|
||
// Extract the function name and remaining arguments.
|
||
wcstring func_name;
|
||
if (!argv.empty()) {
|
||
// Extract and remove the function name from argv.
|
||
func_name = std::move(*argv.begin());
|
||
argv.erase(argv.begin());
|
||
}
|
||
block_t *fb = parser.push_block(block_t::function_block(func_name, argv, props.shadow_scope));
|
||
auto &vars = parser.vars();
|
||
|
||
// Setup the environment for the function. There are three components of the environment:
|
||
// 1. named arguments
|
||
// 2. inherited variables
|
||
// 3. argv
|
||
|
||
size_t idx = 0;
|
||
for (const wcstring &named_arg : props.named_arguments) {
|
||
if (idx < argv.size()) {
|
||
vars.set_one(named_arg, ENV_LOCAL | ENV_USER, argv.at(idx));
|
||
} else {
|
||
vars.set_empty(named_arg, ENV_LOCAL | ENV_USER);
|
||
}
|
||
idx++;
|
||
}
|
||
|
||
for (const auto &kv : props.inherit_vars) {
|
||
vars.set(kv.first, ENV_LOCAL | ENV_USER, kv.second);
|
||
}
|
||
|
||
vars.set_argv(std::move(argv));
|
||
return fb;
|
||
}
|
||
|
||
// Given that we are done executing a function, restore the environment.
|
||
static void function_restore_environment(parser_t &parser, const block_t *block) {
|
||
parser.pop_block(block);
|
||
|
||
// If we returned due to a return statement, then stop returning now.
|
||
parser.libdata().returning = false;
|
||
}
|
||
|
||
// The "performer" function of a block or function process.
|
||
// This accepts a place to execute as \p parser and then executes the result, returning a status.
|
||
// This is factored out in this funny way in preparation for concurrent execution.
|
||
using proc_performer_t = std::function<proc_status_t(parser_t &parser)>;
|
||
|
||
// \return a function which may be to run the given process \p.
|
||
// May return an empty std::function in the rare case that the to-be called fish function no longer
|
||
// exists. This is just a dumb artifact of the fact that we only capture the functions name, not its
|
||
// properties, when creating the job; thus a race could delete the function before we fetch its
|
||
// properties.
|
||
static proc_performer_t get_performer_for_process(process_t *p, job_t *job,
|
||
const io_chain_t &io_chain) {
|
||
assert((p->type == process_type_t::function || p->type == process_type_t::block_node) &&
|
||
"Unexpected process type");
|
||
// We want to capture the job group.
|
||
job_group_ref_t job_group = job->group;
|
||
|
||
if (p->type == process_type_t::block_node) {
|
||
const parsed_source_ref_t &source = p->block_node_source;
|
||
const ast::statement_t *node = p->internal_block_node;
|
||
assert(source && node && "Process is missing node info");
|
||
return [=](parser_t &parser) {
|
||
return parser.eval_node(source, *node, io_chain, job_group).status;
|
||
};
|
||
} else {
|
||
assert(p->type == process_type_t::function);
|
||
auto props = function_get_props(p->argv0());
|
||
if (!props) {
|
||
FLOGF(error, _(L"Unknown function '%ls'"), p->argv0());
|
||
return proc_performer_t{};
|
||
}
|
||
const wcstring_list_t &argv = p->argv();
|
||
return [=](parser_t &parser) {
|
||
// Pull out the job list from the function.
|
||
const ast::job_list_t &body = props->func_node->jobs;
|
||
const block_t *fb = function_prepare_environment(parser, argv, *props);
|
||
auto res = parser.eval_node(props->parsed_source, body, io_chain, job_group);
|
||
function_restore_environment(parser, fb);
|
||
|
||
// If the function did not execute anything, treat it as success.
|
||
if (res.was_empty) {
|
||
res = proc_status_t::from_exit_code(EXIT_SUCCESS);
|
||
}
|
||
return res.status;
|
||
};
|
||
}
|
||
}
|
||
|
||
/// Execute a block node or function "process".
|
||
/// \p piped_output_needs_buffering if true, buffer the output.
|
||
static launch_result_t exec_block_or_func_process(parser_t &parser, const std::shared_ptr<job_t> &j,
|
||
process_t *p, io_chain_t io_chain,
|
||
bool piped_output_needs_buffering) {
|
||
// Create an output buffer if we're piping to another process.
|
||
shared_ptr<io_bufferfill_t> block_output_bufferfill{};
|
||
if (piped_output_needs_buffering) {
|
||
// Be careful to handle failure, e.g. too many open fds.
|
||
block_output_bufferfill = io_bufferfill_t::create();
|
||
if (!block_output_bufferfill) {
|
||
return launch_result_t::failed;
|
||
}
|
||
// Teach the job about its bufferfill, and add it to our io chain.
|
||
io_chain.push_back(block_output_bufferfill);
|
||
}
|
||
|
||
// Get the process performer, and just execute it directly.
|
||
// Do it in this scoped way so that the performer function can be eagerly deallocating releasing
|
||
// its captured io chain.
|
||
if (proc_performer_t performer = get_performer_for_process(p, j.get(), io_chain)) {
|
||
p->status = performer(parser);
|
||
} else {
|
||
return launch_result_t::failed;
|
||
}
|
||
|
||
// If we have a block output buffer, populate it now.
|
||
std::string buffer_contents;
|
||
if (block_output_bufferfill) {
|
||
// Remove our write pipe and forget it. This may close the pipe, unless another thread has
|
||
// claimed it (background write) or another process has inherited it.
|
||
io_chain.remove(block_output_bufferfill);
|
||
buffer_contents =
|
||
io_bufferfill_t::finish(std::move(block_output_bufferfill)).newline_serialized();
|
||
}
|
||
|
||
run_internal_process_or_short_circuit(parser, j, p, std::move(buffer_contents),
|
||
{} /* errdata */, io_chain);
|
||
return launch_result_t::ok;
|
||
}
|
||
|
||
static proc_performer_t get_performer_for_builtin(
|
||
process_t *p, job_t *job, const io_chain_t &io_chain,
|
||
const std::shared_ptr<output_stream_t> &output_stream,
|
||
const std::shared_ptr<output_stream_t> &errput_stream) {
|
||
assert(p->type == process_type_t::builtin && "Process must be a builtin");
|
||
|
||
// Determine if we have a "direct" redirection for stdin.
|
||
bool stdin_is_directly_redirected = false;
|
||
if (!p->is_first_in_job) {
|
||
// We must have a pipe
|
||
stdin_is_directly_redirected = true;
|
||
} else {
|
||
// We are not a pipe. Check if there is a redirection local to the process
|
||
// that's not io_mode_t::close.
|
||
for (const auto &redir : p->redirection_specs()) {
|
||
if (redir.fd == STDIN_FILENO && !redir.is_close()) {
|
||
stdin_is_directly_redirected = true;
|
||
break;
|
||
}
|
||
}
|
||
}
|
||
|
||
// Pull out some fields which we want to copy. We don't want to store the process or job in the
|
||
// returned closure.
|
||
job_group_ref_t job_group = job->group;
|
||
const wcstring_list_t &argv = p->argv();
|
||
|
||
// Be careful to not capture p or j by value, as the intent is that this may be run on another
|
||
// thread.
|
||
return [=](parser_t &parser) {
|
||
auto out_io = io_chain.io_for_fd(STDOUT_FILENO);
|
||
auto err_io = io_chain.io_for_fd(STDERR_FILENO);
|
||
|
||
// Figure out what fd to use for the builtin's stdin.
|
||
int local_builtin_stdin = STDIN_FILENO;
|
||
if (const auto in = io_chain.io_for_fd(STDIN_FILENO)) {
|
||
// Ignore fd redirections from an fd other than the
|
||
// standard ones. e.g. in source <&3 don't actually read from fd 3,
|
||
// which is internal to fish. We still respect this redirection in
|
||
// that we pass it on as a block IO to the code that source runs,
|
||
// and therefore this is not an error.
|
||
bool ignore_redirect = in->io_mode == io_mode_t::fd && in->source_fd >= 3;
|
||
if (!ignore_redirect) {
|
||
local_builtin_stdin = in->source_fd;
|
||
}
|
||
}
|
||
|
||
// Populate our io_streams_t. This is a bag of information for the builtin.
|
||
io_streams_t streams{*output_stream, *errput_stream};
|
||
streams.job_group = job_group;
|
||
streams.stdin_fd = local_builtin_stdin;
|
||
streams.stdin_is_directly_redirected = stdin_is_directly_redirected;
|
||
streams.out_is_redirected = out_io != nullptr;
|
||
streams.err_is_redirected = err_io != nullptr;
|
||
streams.out_is_piped = (out_io && out_io->io_mode == io_mode_t::pipe);
|
||
streams.err_is_piped = (err_io && err_io->io_mode == io_mode_t::pipe);
|
||
streams.io_chain = &io_chain;
|
||
|
||
// Execute the builtin.
|
||
return builtin_run(parser, argv, streams);
|
||
};
|
||
}
|
||
|
||
/// Executes a builtin "process".
|
||
static launch_result_t exec_builtin_process(parser_t &parser, const std::shared_ptr<job_t> &j,
|
||
process_t *p, const io_chain_t &io_chain,
|
||
bool piped_output_needs_buffering) {
|
||
assert(p->type == process_type_t::builtin && "Process is not a builtin");
|
||
std::shared_ptr<output_stream_t> out =
|
||
create_output_stream_for_builtin(STDOUT_FILENO, io_chain, piped_output_needs_buffering);
|
||
std::shared_ptr<output_stream_t> err =
|
||
create_output_stream_for_builtin(STDERR_FILENO, io_chain, piped_output_needs_buffering);
|
||
|
||
if (proc_performer_t performer = get_performer_for_builtin(p, j.get(), io_chain, out, err)) {
|
||
p->status = performer(parser);
|
||
} else {
|
||
return launch_result_t::failed;
|
||
}
|
||
handle_builtin_output(parser, j, p, io_chain, *out, *err);
|
||
return launch_result_t::ok;
|
||
}
|
||
|
||
/// Executes a process \p \p in \p job, using the pipes \p pipes (which may have invalid fds if this
|
||
/// is the first or last process).
|
||
/// \p deferred_pipes represents the pipes from our deferred process; if set ensure they get closed
|
||
/// in any child. If \p is_deferred_run is true, then this is a deferred run; this affects how
|
||
/// certain buffering works.
|
||
/// An error return here indicates that the process failed to launch, and the rest of
|
||
/// the pipeline should be cancelled.
|
||
static launch_result_t exec_process_in_job(parser_t &parser, process_t *p,
|
||
const std::shared_ptr<job_t> &j,
|
||
const io_chain_t &block_io, autoclose_pipes_t pipes,
|
||
const autoclose_pipes_t &deferred_pipes,
|
||
bool is_deferred_run = false) {
|
||
// The write pipe (destined for stdout) needs to occur before redirections. For example,
|
||
// with a redirection like this:
|
||
//
|
||
// `foo 2>&1 | bar`
|
||
//
|
||
// what we want to happen is this:
|
||
//
|
||
// dup2(pipe, stdout)
|
||
// dup2(stdout, stderr)
|
||
//
|
||
// so that stdout and stderr both wind up referencing the pipe.
|
||
//
|
||
// The read pipe (destined for stdin) is more ambiguous. Imagine a pipeline like this:
|
||
//
|
||
// echo alpha | cat < beta.txt
|
||
//
|
||
// Should cat output alpha or beta? bash and ksh output 'beta', tcsh gets it right and
|
||
// complains about ambiguity, and zsh outputs both (!). No shells appear to output 'alpha',
|
||
// so we match bash here. That would mean putting the pipe first, so that it gets trumped by
|
||
// the file redirection.
|
||
//
|
||
// However, eval does this:
|
||
//
|
||
// echo "begin; $argv "\n" ;end <&3 3<&-" | source 3<&0
|
||
//
|
||
// which depends on the redirection being evaluated before the pipe. So the write end of the
|
||
// pipe comes first, the read pipe of the pipe comes last. See issue #966.
|
||
|
||
// Maybe trace this process.
|
||
// TODO: 'and' and 'or' will not show.
|
||
if (trace_enabled(parser)) {
|
||
trace_argv(parser, nullptr, p->argv());
|
||
}
|
||
|
||
// The IO chain for this process.
|
||
io_chain_t process_net_io_chain = block_io;
|
||
|
||
if (pipes.write.valid()) {
|
||
process_net_io_chain.push_back(std::make_shared<io_pipe_t>(
|
||
p->pipe_write_fd, false /* not input */, std::move(pipes.write)));
|
||
}
|
||
|
||
// Append IOs from the process's redirection specs.
|
||
// This may fail, e.g. a failed redirection.
|
||
if (!process_net_io_chain.append_from_specs(p->redirection_specs(),
|
||
parser.vars().get_pwd_slash())) {
|
||
return launch_result_t::failed;
|
||
}
|
||
|
||
// Read pipe goes last.
|
||
shared_ptr<io_pipe_t> pipe_read{};
|
||
if (pipes.read.valid()) {
|
||
pipe_read =
|
||
std::make_shared<io_pipe_t>(STDIN_FILENO, true /* input */, std::move(pipes.read));
|
||
process_net_io_chain.push_back(pipe_read);
|
||
}
|
||
|
||
// If we have stashed pipes, make sure those get closed in the child.
|
||
for (const autoclose_fd_t *afd : {&deferred_pipes.read, &deferred_pipes.write}) {
|
||
if (afd->valid()) {
|
||
process_net_io_chain.push_back(std::make_shared<io_close_t>(afd->fd()));
|
||
}
|
||
}
|
||
|
||
if (p->type != process_type_t::block_node) {
|
||
// A simple `begin ... end` should not be considered an execution of a command.
|
||
parser.libdata().exec_count++;
|
||
}
|
||
|
||
const block_t *block = nullptr;
|
||
cleanup_t pop_block([&]() {
|
||
if (block) parser.pop_block(block);
|
||
});
|
||
if (!p->variable_assignments.empty()) {
|
||
block = parser.push_block(block_t::variable_assignment_block());
|
||
}
|
||
for (const auto &assignment : p->variable_assignments) {
|
||
parser.vars().set(assignment.variable_name, ENV_LOCAL | ENV_EXPORT, assignment.values);
|
||
}
|
||
|
||
// Decide if outputting to a pipe may deadlock.
|
||
// This happens if fish pipes from an internal process into another internal process:
|
||
// echo $big | string match...
|
||
// Here fish will only run one process at a time, so the pipe buffer may overfill.
|
||
// It may also happen when piping internal -> external:
|
||
// echo $big | external_proc
|
||
// fish wants to run `echo` before launching external_proc, so the pipe may deadlock.
|
||
// However if we are a deferred run, it means that we are piping into an external process
|
||
// which got launched before us!
|
||
bool piped_output_needs_buffering = !p->is_last_in_job && !is_deferred_run;
|
||
|
||
// Execute the process.
|
||
p->check_generations_before_launch();
|
||
switch (p->type) {
|
||
case process_type_t::function:
|
||
case process_type_t::block_node: {
|
||
if (exec_block_or_func_process(parser, j, p, process_net_io_chain,
|
||
piped_output_needs_buffering) ==
|
||
launch_result_t::failed) {
|
||
return launch_result_t::failed;
|
||
}
|
||
break;
|
||
}
|
||
|
||
case process_type_t::builtin: {
|
||
if (exec_builtin_process(parser, j, p, process_net_io_chain,
|
||
piped_output_needs_buffering) == launch_result_t::failed) {
|
||
return launch_result_t::failed;
|
||
}
|
||
break;
|
||
}
|
||
|
||
case process_type_t::external: {
|
||
if (exec_external_command(parser, j, p, process_net_io_chain) ==
|
||
launch_result_t::failed) {
|
||
return launch_result_t::failed;
|
||
}
|
||
// It's possible (though unlikely) that this is a background process which recycled a
|
||
// pid from another, previous background process. Forget any such old process.
|
||
parser.get_wait_handles().remove_by_pid(p->pid);
|
||
break;
|
||
}
|
||
|
||
case process_type_t::exec: {
|
||
// We should have handled exec up above.
|
||
DIE("process_type_t::exec process found in pipeline, where it should never be. "
|
||
"Aborting.");
|
||
}
|
||
}
|
||
return launch_result_t::ok;
|
||
}
|
||
|
||
// Do we have a fish internal process that pipes into a real process? If so, we are going to
|
||
// launch it last (if there's more than one, just the last one). That is to prevent buffering
|
||
// from blocking further processes. See #1396.
|
||
// Example:
|
||
// for i in (seq 1 5); sleep 1; echo $i; end | cat
|
||
// This should show the output as it comes, not buffer until the end.
|
||
// Any such process (only one per job) will be called the "deferred" process.
|
||
static process_t *get_deferred_process(const shared_ptr<job_t> &j) {
|
||
// Common case is no deferred proc.
|
||
if (j->processes.size() <= 1) return nullptr;
|
||
|
||
// Skip execs, which can only appear at the front.
|
||
if (j->processes.front()->type == process_type_t::exec) return nullptr;
|
||
|
||
// Find the last non-external process, and return it if it pipes into an extenal process.
|
||
for (auto i = j->processes.rbegin(); i != j->processes.rend(); ++i) {
|
||
process_t *p = i->get();
|
||
if (p->type != process_type_t::external) {
|
||
return p->is_last_in_job ? nullptr : p;
|
||
}
|
||
}
|
||
return nullptr;
|
||
}
|
||
|
||
/// Given that we failed to execute process \p failed_proc in job \p job, mark that process and
|
||
/// every subsequent process in the pipeline as aborted before launch.
|
||
static void abort_pipeline_from(const shared_ptr<job_t> &job, const process_t *failed_proc) {
|
||
bool found = false;
|
||
for (process_ptr_t &p : job->processes) {
|
||
found = found || (p.get() == failed_proc);
|
||
if (found) p->mark_aborted_before_launch();
|
||
}
|
||
assert(found && "Process not present in job");
|
||
}
|
||
|
||
// Given that we are about to execute an exec() call, check if the parser is interactive and there
|
||
// are extant background jobs. If so, warn the user and do not exec().
|
||
// \return true if we should allow exec, false to disallow it.
|
||
static bool allow_exec_with_background_jobs(parser_t &parser) {
|
||
// If we're not interactive, we cannot warn.
|
||
if (!parser.is_interactive()) return true;
|
||
|
||
// Construct the list of running background jobs.
|
||
job_list_t bgs = jobs_requiring_warning_on_exit(parser);
|
||
if (bgs.empty()) return true;
|
||
|
||
// Compare run counts, so we only warn once.
|
||
uint64_t current_run_count = reader_run_count();
|
||
uint64_t &last_exec_run_count = parser.libdata().last_exec_run_counter;
|
||
if (isatty(STDIN_FILENO) && current_run_count - 1 != last_exec_run_count) {
|
||
print_exit_warning_for_jobs(bgs);
|
||
last_exec_run_count = current_run_count;
|
||
return false;
|
||
} else {
|
||
hup_jobs(parser.jobs());
|
||
return true;
|
||
}
|
||
}
|
||
|
||
bool exec_job(parser_t &parser, const shared_ptr<job_t> &j, const io_chain_t &block_io) {
|
||
assert(j && "null job_t passed to exec_job!");
|
||
|
||
// If fish was invoked with -n or --no-execute, then no_exec will be set and we do nothing.
|
||
if (no_exec()) {
|
||
return true;
|
||
}
|
||
|
||
// Handle an exec call.
|
||
if (j->processes.front()->type == process_type_t::exec) {
|
||
// If we are interactive, perhaps disallow exec if there are background jobs.
|
||
if (!allow_exec_with_background_jobs(parser)) {
|
||
for (const auto &p : j->processes) {
|
||
p->mark_aborted_before_launch();
|
||
}
|
||
return false;
|
||
}
|
||
|
||
internal_exec(parser.vars(), j.get(), block_io);
|
||
// internal_exec only returns if it failed to set up redirections.
|
||
// In case of an successful exec, this code is not reached.
|
||
int status = j->flags().negate ? 0 : 1;
|
||
parser.set_last_statuses(statuses_t::just(status));
|
||
|
||
// A false return tells the caller to remove the job from the list.
|
||
for (const auto &p : j->processes) {
|
||
p->mark_aborted_before_launch();
|
||
}
|
||
return false;
|
||
}
|
||
cleanup_t timer = push_timer(j->wants_timing() && !no_exec());
|
||
|
||
// Get the deferred process, if any. We will have to remember its pipes.
|
||
autoclose_pipes_t deferred_pipes;
|
||
process_t *const deferred_process = get_deferred_process(j);
|
||
|
||
// We may want to transfer tty ownership to the pgroup leader.
|
||
tty_transfer_t transfer{};
|
||
|
||
// This loop loops over every process_t in the job, starting it as appropriate. This turns out
|
||
// to be rather complex, since a process_t can be one of many rather different things.
|
||
//
|
||
// The loop also has to handle pipelining between the jobs.
|
||
//
|
||
// We can have up to three pipes "in flight" at a time:
|
||
//
|
||
// 1. The pipe the current process should read from (courtesy of the previous process)
|
||
// 2. The pipe that the current process should write to
|
||
// 3. The pipe that the next process should read from (courtesy of us)
|
||
//
|
||
// Lastly, a process may experience a pipeline-aborting error, which prevents launching
|
||
// further processes in the pipeline.
|
||
autoclose_fd_t pipe_next_read;
|
||
bool aborted_pipeline = false;
|
||
size_t procs_launched = 0;
|
||
for (const auto &procptr : j->processes) {
|
||
process_t *p = procptr.get();
|
||
|
||
// proc_pipes is the pipes applied to this process. That is, it is the read end
|
||
// containing the output of the previous process (if any), plus the write end that will
|
||
// output to the next process (if any).
|
||
autoclose_pipes_t proc_pipes;
|
||
proc_pipes.read = std::move(pipe_next_read);
|
||
if (!p->is_last_in_job) {
|
||
auto pipes = make_autoclose_pipes();
|
||
if (!pipes) {
|
||
FLOGF(warning, PIPE_ERROR);
|
||
wperror(L"pipe");
|
||
aborted_pipeline = true;
|
||
abort_pipeline_from(j, p);
|
||
break;
|
||
}
|
||
pipe_next_read = std::move(pipes->read);
|
||
proc_pipes.write = std::move(pipes->write);
|
||
|
||
// Save any deferred process for last. By definition, the deferred process can never be
|
||
// the last process in the job, so it's safe to nest this in the outer
|
||
// `if (!p->is_last_in_job)` block, which makes it clear that `proc_next_read` will
|
||
// always be assigned when we `continue` the loop.
|
||
if (p == deferred_process) {
|
||
deferred_pipes = std::move(proc_pipes);
|
||
continue;
|
||
}
|
||
}
|
||
|
||
// Regular process.
|
||
if (exec_process_in_job(parser, p, j, block_io, std::move(proc_pipes), deferred_pipes) ==
|
||
launch_result_t::failed) {
|
||
aborted_pipeline = true;
|
||
abort_pipeline_from(j, p);
|
||
break;
|
||
}
|
||
procs_launched += 1;
|
||
|
||
// Transfer tty?
|
||
if (p->leads_pgrp && j->group->wants_terminal()) {
|
||
transfer.to_job_group(j->group);
|
||
}
|
||
}
|
||
pipe_next_read.close();
|
||
|
||
// If our pipeline was aborted before any process was successfully launched, then there is
|
||
// nothing to reap, and we can perform an early return.
|
||
// Note we must never return false if we have launched even one process, since it will not be
|
||
// properly reaped; see #7038.
|
||
if (aborted_pipeline && procs_launched == 0) {
|
||
return false;
|
||
}
|
||
|
||
// Ok, at least one thing got launched.
|
||
// Handle any deferred process.
|
||
if (deferred_process) {
|
||
if (aborted_pipeline) {
|
||
// Some other process already aborted our pipeline.
|
||
deferred_process->mark_aborted_before_launch();
|
||
} else if (exec_process_in_job(parser, deferred_process, j, block_io,
|
||
std::move(deferred_pipes), {},
|
||
true) == launch_result_t::failed) {
|
||
// The deferred proc itself failed to launch.
|
||
deferred_process->mark_aborted_before_launch();
|
||
}
|
||
}
|
||
|
||
FLOGF(exec_job_exec, L"Executed job %d from command '%ls'", j->job_id(), j->command_wcstr());
|
||
|
||
j->mark_constructed();
|
||
|
||
// If exec_error then a backgrounded job would have been terminated before it was ever assigned
|
||
// a pgroup, so error out before setting last_pid.
|
||
if (!j->is_foreground()) {
|
||
maybe_t<pid_t> last_pid = j->get_last_pid();
|
||
if (last_pid.has_value()) {
|
||
parser.vars().set_one(L"last_pid", ENV_GLOBAL, to_string(*last_pid));
|
||
} else {
|
||
parser.vars().set_empty(L"last_pid", ENV_GLOBAL);
|
||
}
|
||
}
|
||
|
||
if (!j->is_initially_background()) {
|
||
j->continue_job(parser);
|
||
}
|
||
|
||
if (j->is_stopped()) transfer.save_tty_modes();
|
||
transfer.reclaim();
|
||
return true;
|
||
}
|
||
|
||
/// Populate \p lst with the output of \p buffer, perhaps splitting lines according to \p split.
|
||
static void populate_subshell_output(wcstring_list_t *lst, const separated_buffer_t &buffer,
|
||
bool split) {
|
||
// Walk over all the elements.
|
||
for (const auto &elem : buffer.elements()) {
|
||
if (elem.is_explicitly_separated()) {
|
||
// Just append this one.
|
||
lst->push_back(str2wcstring(elem.contents));
|
||
continue;
|
||
}
|
||
|
||
// Not explicitly separated. We have to split it explicitly.
|
||
assert(!elem.is_explicitly_separated() && "should not be explicitly separated");
|
||
const char *begin = elem.contents.data();
|
||
const char *end = begin + elem.contents.size();
|
||
if (split) {
|
||
const char *cursor = begin;
|
||
while (cursor < end) {
|
||
// Look for the next separator.
|
||
auto stop = static_cast<const char *>(std::memchr(cursor, '\n', end - cursor));
|
||
const bool hit_separator = (stop != nullptr);
|
||
if (!hit_separator) {
|
||
// If it's not found, just use the end.
|
||
stop = end;
|
||
}
|
||
// Stop now points at the first character we do not want to copy.
|
||
lst->push_back(str2wcstring(cursor, stop - cursor));
|
||
|
||
// If we hit a separator, skip over it; otherwise we're at the end.
|
||
cursor = stop + (hit_separator ? 1 : 0);
|
||
}
|
||
} else {
|
||
// We're not splitting output, but we still want to trim off a trailing newline.
|
||
if (end != begin && end[-1] == '\n') {
|
||
--end;
|
||
}
|
||
lst->push_back(str2wcstring(begin, end - begin));
|
||
}
|
||
}
|
||
}
|
||
|
||
/// Execute \p cmd in a subshell in \p parser. If \p lst is not null, populate it with the output.
|
||
/// Return $status in \p out_status.
|
||
/// If \p job_group is set, any spawned commands should join that job group.
|
||
/// If \p apply_exit_status is false, then reset $status back to its original value.
|
||
/// \p is_subcmd controls whether we apply a read limit.
|
||
/// \p break_expand is used to propagate whether the result should be "expansion breaking" in the
|
||
/// sense that subshells used during string expansion should halt that expansion. \return the value
|
||
/// of $status.
|
||
static int exec_subshell_internal(const wcstring &cmd, parser_t &parser,
|
||
const job_group_ref_t &job_group, wcstring_list_t *lst,
|
||
bool *break_expand, bool apply_exit_status, bool is_subcmd) {
|
||
parser.assert_can_execute();
|
||
auto &ld = parser.libdata();
|
||
|
||
scoped_push<bool> is_subshell(&ld.is_subshell, true);
|
||
scoped_push<size_t> read_limit(&ld.read_limit, is_subcmd ? read_byte_limit : 0);
|
||
|
||
auto prev_statuses = parser.get_last_statuses();
|
||
const cleanup_t put_back([&] {
|
||
if (!apply_exit_status) {
|
||
parser.set_last_statuses(prev_statuses);
|
||
}
|
||
});
|
||
|
||
const bool split_output = !parser.vars().get(L"IFS").missing_or_empty();
|
||
|
||
// IO buffer creation may fail (e.g. if we have too many open files to make a pipe), so this may
|
||
// be null.
|
||
auto bufferfill = io_bufferfill_t::create(ld.read_limit);
|
||
if (!bufferfill) {
|
||
*break_expand = true;
|
||
return STATUS_CMD_ERROR;
|
||
}
|
||
eval_res_t eval_res = parser.eval(cmd, io_chain_t{bufferfill}, job_group, block_type_t::subst);
|
||
separated_buffer_t buffer = io_bufferfill_t::finish(std::move(bufferfill));
|
||
if (buffer.discarded()) {
|
||
*break_expand = true;
|
||
return STATUS_READ_TOO_MUCH;
|
||
}
|
||
|
||
if (eval_res.break_expand) {
|
||
*break_expand = true;
|
||
return eval_res.status.status_value();
|
||
}
|
||
|
||
if (lst) {
|
||
populate_subshell_output(lst, buffer, split_output);
|
||
}
|
||
*break_expand = false;
|
||
return eval_res.status.status_value();
|
||
}
|
||
|
||
int exec_subshell_for_expand(const wcstring &cmd, parser_t &parser,
|
||
const job_group_ref_t &job_group, wcstring_list_t &outputs) {
|
||
parser.assert_can_execute();
|
||
bool break_expand = false;
|
||
int ret = exec_subshell_internal(cmd, parser, job_group, &outputs, &break_expand, true, true);
|
||
// Only return an error code if we should break expansion.
|
||
return break_expand ? ret : STATUS_CMD_OK;
|
||
}
|
||
|
||
int exec_subshell(const wcstring &cmd, parser_t &parser, bool apply_exit_status) {
|
||
bool break_expand = false;
|
||
return exec_subshell_internal(cmd, parser, nullptr, nullptr, &break_expand, apply_exit_status,
|
||
false);
|
||
}
|
||
|
||
int exec_subshell(const wcstring &cmd, parser_t &parser, wcstring_list_t &outputs,
|
||
bool apply_exit_status) {
|
||
bool break_expand = false;
|
||
return exec_subshell_internal(cmd, parser, nullptr, &outputs, &break_expand, apply_exit_status,
|
||
false);
|
||
}
|