mirror of
https://github.com/fish-shell/fish-shell
synced 2024-12-27 05:13:10 +00:00
0b3eca1743
Now that we use an internal process to perform builtin output, simplify the logic around how it is performed. In particular we no longer have to be careful about async-safe functions since we do not fork. Also fix a bunch of comments that no longer apply.
1148 lines
45 KiB
C++
1148 lines
45 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 <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 <signal.h>
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#ifdef HAVE_SPAWN_H
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#include <spawn.h>
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#endif
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#include <stdio.h>
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#include <string.h>
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#include <sys/wait.h>
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#include <unistd.h>
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#include <stack>
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#include <algorithm>
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#include <functional>
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#include <map>
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#include <memory>
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#include <string>
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#include <type_traits>
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#include <vector>
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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 "function.h"
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#include "io.h"
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#include "iothread.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 "signal.h"
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#include "wutil.h" // IWYU pragma: keep
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/// File descriptor redirection error message.
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#define FD_ERROR _(L"An error occurred while redirecting file descriptor %d")
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/// File descriptor redirection error message.
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#define WRITE_ERROR _(L"An error occurred while writing output")
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/// File redirection error message.
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#define FILE_ERROR _(L"An error occurred while redirecting file '%s'")
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/// Base open mode to pass to calls to open.
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#define OPEN_MASK 0666
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void exec_close(int fd) {
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ASSERT_IS_MAIN_THREAD();
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// This may be called in a child of fork(), so don't allocate memory.
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if (fd < 0) {
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debug(0, L"Called close on invalid file descriptor ");
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return;
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}
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while (close(fd) == -1) {
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debug(1, FD_ERROR, fd);
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wperror(L"close");
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break;
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}
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}
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/// Returns true if the redirection is a file redirection to a file other than /dev/null.
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static bool redirection_is_to_real_file(const shared_ptr<io_data_t> &io) {
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bool result = false;
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if (io && io->io_mode == io_mode_t::file) {
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// It's a file redirection. Compare the path to /dev/null.
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const char *path = static_cast<const io_file_t *>(io.get())->filename_cstr;
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if (strcmp(path, "/dev/null") != 0) {
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// It's not /dev/null.
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result = true;
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}
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}
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return result;
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}
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/// Returns the interpreter for the specified script. Returns NULL if file is not a script with a
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/// shebang.
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char *get_interpreter(const char *command, char *interpreter, size_t buff_size) {
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// OK to not use CLO_EXEC here because this is only called after fork.
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int fd = open(command, O_RDONLY);
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if (fd >= 0) {
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size_t idx = 0;
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while (idx + 1 < buff_size) {
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char ch;
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ssize_t amt = read(fd, &ch, sizeof ch);
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if (amt <= 0) break;
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if (ch == '\n') break;
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interpreter[idx++] = ch;
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}
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interpreter[idx++] = '\0';
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close(fd);
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}
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if (strncmp(interpreter, "#! /", 4) == 0) {
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return interpreter + 3;
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} else if (strncmp(interpreter, "#!/", 3) == 0) {
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return interpreter + 2;
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}
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return NULL;
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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 setup_child_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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static void safe_launch_process(process_t *p, const char *actual_cmd, const char *const *cargv,
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const char *const *cenvv) {
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UNUSED(p);
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int err;
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// debug( 1, L"exec '%ls'", p->argv[0] );
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// This function never returns, so we take certain liberties with constness.
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char *const *envv = const_cast<char *const *>(cenvv);
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char *const *argv = const_cast<char *const *>(cargv);
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execve(actual_cmd, argv, envv);
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err = errno;
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// Something went wrong with execve, check for a ":", and run /bin/sh if encountered. This is a
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// weird predecessor to the shebang that is still sometimes used since it is supported on
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// Windows. OK to not use CLO_EXEC here because this is called after fork and the file is
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// immediately closed.
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int fd = open(actual_cmd, O_RDONLY);
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if (fd >= 0) {
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char begin[1] = {0};
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ssize_t amt_read = read(fd, begin, 1);
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close(fd);
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if ((amt_read == 1) && (begin[0] == ':')) {
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// Relaunch it with /bin/sh. Don't allocate memory, so if you have more args than this,
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// update your silly script! Maybe this should be changed to be based on ARG_MAX
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// somehow.
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char sh_command[] = "/bin/sh";
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char *argv2[128];
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argv2[0] = sh_command;
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for (size_t i = 1; i < sizeof argv2 / sizeof *argv2; i++) {
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argv2[i] = argv[i - 1];
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if (argv2[i] == NULL) break;
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}
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execve(sh_command, 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(STATUS_EXEC_FAIL);
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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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static void launch_process_nofork(env_stack_t &vars, process_t *p) {
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ASSERT_IS_MAIN_THREAD();
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ASSERT_IS_NOT_FORKED_CHILD();
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null_terminated_array_t<char> argv_array;
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convert_wide_array_to_narrow(p->get_argv_array(), &argv_array);
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const char *const *envv = vars.export_arr();
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char *actual_cmd = wcs2str(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, argv_array.get(), envv);
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}
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/// Check if the IO redirection chains contains redirections for the specified file descriptor.
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static int has_fd(const io_chain_t &d, int fd) { return io_chain_get(d, fd).get() != NULL; }
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/// Close a list of fds.
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static void io_cleanup_fds(const std::vector<int> &opened_fds) {
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std::for_each(opened_fds.begin(), opened_fds.end(), close);
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}
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/// Make a copy of the specified io redirection chain, but change file redirection into fd
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/// redirection. This makes the redirection chain suitable for use as block-level io, since the file
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/// won't be repeatedly reopened for every command in the block, which would reset the cursor
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/// position.
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///
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/// \return true on success, false on failure. Returns the output chain and opened_fds by reference.
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static bool io_transmogrify(const io_chain_t &in_chain, io_chain_t *out_chain,
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std::vector<int> *out_opened_fds) {
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ASSERT_IS_MAIN_THREAD();
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assert(out_chain != NULL && out_opened_fds != NULL);
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assert(out_chain->empty());
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// Just to be clear what we do for an empty chain.
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if (in_chain.empty()) {
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return true;
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}
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bool success = true;
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// Make our chain of redirections.
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io_chain_t result_chain;
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// In the event we can't finish transmorgrifying, we'll have to close all the files we opened.
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std::vector<int> opened_fds;
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for (size_t idx = 0; idx < in_chain.size(); idx++) {
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const shared_ptr<io_data_t> &in = in_chain.at(idx);
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shared_ptr<io_data_t> out; // gets allocated via new
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switch (in->io_mode) {
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case io_mode_t::pipe:
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case io_mode_t::bufferfill:
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case io_mode_t::fd:
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case io_mode_t::close: {
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// These redirections don't need transmogrification. They can be passed through.
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out = in;
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break;
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}
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case io_mode_t::file: {
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// Transmogrify file redirections.
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int fd;
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io_file_t *in_file = static_cast<io_file_t *>(in.get());
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if ((fd = open(in_file->filename_cstr, in_file->flags, OPEN_MASK)) == -1) {
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debug(1, FILE_ERROR, in_file->filename_cstr);
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wperror(L"open");
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success = false;
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break;
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}
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opened_fds.push_back(fd);
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out.reset(new io_fd_t(in->fd, fd, false));
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break;
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}
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}
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if (out.get() != NULL) result_chain.push_back(out);
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// Don't go any further if we failed.
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if (!success) {
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break;
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}
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}
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// Now either return success, or clean up.
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if (success) {
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*out_chain = std::move(result_chain);
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*out_opened_fds = std::move(opened_fds);
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} else {
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result_chain.clear();
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io_cleanup_fds(opened_fds);
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}
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return success;
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}
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/// Morph an io redirection chain into redirections suitable for passing to eval, call eval, and
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/// clean up morphed redirections.
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///
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/// \param parsed_source the parsed source code containing the node to evaluate
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/// \param node the node to evaluate
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/// \param ios the io redirections to be performed on this block
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template <typename T>
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void internal_exec_helper(parser_t &parser, parsed_source_ref_t parsed_source, tnode_t<T> node,
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const io_chain_t &ios, std::shared_ptr<job_t> parent_job) {
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assert(parsed_source && node && "exec_helper missing source or without node");
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io_chain_t morphed_chain;
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std::vector<int> opened_fds;
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bool transmorgrified = io_transmogrify(ios, &morphed_chain, &opened_fds);
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// Did the transmogrification fail - if so, set error status and return.
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if (!transmorgrified) {
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proc_set_last_status(STATUS_EXEC_FAIL);
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return;
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}
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parser.eval_node(parsed_source, node, morphed_chain, TOP, parent_job);
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morphed_chain.clear();
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io_cleanup_fds(opened_fds);
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job_reap(false);
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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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if (job->get_flag(job_flag_t::JOB_CONTROL)) { //!OCLINT(collapsible if statements)
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// We are going to use job control; therefore when we launch this job it will get its own
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// process group ID. But will it be foregrounded?
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if (job->get_flag(job_flag_t::TERMINAL) && job->is_foreground()) {
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// It 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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}
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return true;
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}
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void internal_exec(env_stack_t &vars, job_t *j, const io_chain_t &all_ios) {
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// Do a regular launch - but without forking first...
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// setup_child_process makes sure signals are properly set up.
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// PCA This is for handling exec. Passing all_ios here matches what fish 2.0.0 and 1.x did.
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// It's known to be wrong - for example, it means that redirections bound for subsequent
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// commands in the pipeline will apply to exec. However, using exec in a pipeline doesn't
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// really make sense, so I'm not trying to fix it here.
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auto redirs = dup2_list_t::resolve_chain(all_ios);
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if (redirs && !setup_child_process(0, *redirs)) {
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// Decrement SHLVL as we're removing ourselves from the shell "stack".
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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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// launch_process _never_ returns.
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launch_process_nofork(vars, j->processes.front().get());
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} else {
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j->set_flag(job_flag_t::CONSTRUCTED, true);
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j->processes.front()->completed = 1;
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return;
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}
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}
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static void on_process_created(const std::shared_ptr<job_t> &j, pid_t child_pid) {
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// We only need to do this the first time a child is forked/spawned
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if (j->pgid != INVALID_PID) {
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return;
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}
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if (j->get_flag(job_flag_t::JOB_CONTROL)) {
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j->pgid = child_pid;
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} else {
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j->pgid = getpgrp();
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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 bool run_internal_process(process_t *p, std::string outdata, std::string errdata,
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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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int 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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// 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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if (!f->dup2s) {
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return false;
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}
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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 right 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(EXIT_SUCCESS);
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return true;
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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([f]() {
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int 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) status = 1;
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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) status = 1;
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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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return true;
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}
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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. Returns true if fork succeeded, false if fork failed.
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static bool fork_child_for_process(const std::shared_ptr<job_t> &job, process_t *p,
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const dup2_list_t &dup2s, bool drain_threads,
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const char *fork_type,
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const std::function<void()> &child_action) {
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pid_t pid = execute_fork(drain_threads);
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if (pid == 0) {
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// This is the child process. Setup redirections, print correct output to
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// stdout and stderr, and then exit.
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p->pid = getpid();
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child_set_group(job.get(), p);
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setup_child_process(p, dup2s);
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child_action();
|
|
DIE("Child process returned control to fork_child lambda!");
|
|
}
|
|
|
|
if (pid < 0) {
|
|
debug(1, L"Failed to fork %s!\n", fork_type);
|
|
job_mark_process_as_failed(job, p);
|
|
return false;
|
|
}
|
|
|
|
// This is the parent process. Store away information on the child, and
|
|
// possibly give it control over the terminal.
|
|
debug(4, L"Fork #%d, pid %d: %s for '%ls'", g_fork_count, pid, fork_type, p->argv0());
|
|
|
|
p->pid = pid;
|
|
on_process_created(job, p->pid);
|
|
set_child_group(job.get(), p->pid);
|
|
maybe_assign_terminal(job.get());
|
|
return true;
|
|
}
|
|
|
|
/// Execute an internal builtin. Given a parser, a job within that parser, and a process within that
|
|
/// job corresponding to a builtin, execute the builtin with the given streams. If pipe_read is set,
|
|
/// assign stdin to it; otherwise infer stdin from the IO chain.
|
|
/// \return true on success, false if there is an exec error.
|
|
static bool exec_internal_builtin_proc(parser_t &parser, const std::shared_ptr<job_t> &j,
|
|
process_t *p, const io_pipe_t *pipe_read,
|
|
const io_chain_t &proc_io_chain, io_streams_t &streams) {
|
|
assert(p->type == INTERNAL_BUILTIN && "Process must be a builtin");
|
|
int local_builtin_stdin = STDIN_FILENO;
|
|
autoclose_fd_t locally_opened_stdin{};
|
|
|
|
// If this is the first process, check the io redirections and see where we should
|
|
// be reading from.
|
|
if (pipe_read) {
|
|
local_builtin_stdin = pipe_read->pipe_fd();
|
|
} else if (const auto in = proc_io_chain.get_io_for_fd(STDIN_FILENO)) {
|
|
switch (in->io_mode) {
|
|
case io_mode_t::fd: {
|
|
const io_fd_t *in_fd = static_cast<const io_fd_t *>(in.get());
|
|
// Ignore user-supplied 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. Non-user supplied fd
|
|
// redirections come about through transmogrification, and we need
|
|
// to respect those here.
|
|
if (!in_fd->user_supplied || (in_fd->old_fd >= 0 && in_fd->old_fd < 3)) {
|
|
local_builtin_stdin = in_fd->old_fd;
|
|
}
|
|
break;
|
|
}
|
|
case io_mode_t::pipe: {
|
|
const io_pipe_t *in_pipe = static_cast<const io_pipe_t *>(in.get());
|
|
if (in_pipe->fd == STDIN_FILENO) {
|
|
local_builtin_stdin = in_pipe->pipe_fd();
|
|
}
|
|
break;
|
|
}
|
|
case io_mode_t::file: {
|
|
const io_file_t *in_file = static_cast<const io_file_t *>(in.get());
|
|
locally_opened_stdin =
|
|
autoclose_fd_t{open(in_file->filename_cstr, in_file->flags, OPEN_MASK)};
|
|
if (!locally_opened_stdin.valid()) {
|
|
debug(1, FILE_ERROR, in_file->filename_cstr);
|
|
wperror(L"open");
|
|
}
|
|
local_builtin_stdin = locally_opened_stdin.fd();
|
|
break;
|
|
}
|
|
case io_mode_t::close: {
|
|
// FIXME: When requesting that stdin be closed, we really don't do
|
|
// anything. How should this be handled?
|
|
local_builtin_stdin = -1;
|
|
|
|
break;
|
|
}
|
|
default: {
|
|
local_builtin_stdin = -1;
|
|
debug(1, _(L"Unknown input redirection type %d"), in->io_mode);
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
|
|
if (local_builtin_stdin == -1) return false;
|
|
|
|
// Determine if we have a "direct" redirection for stdin.
|
|
bool stdin_is_directly_redirected;
|
|
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.
|
|
const shared_ptr<const io_data_t> stdin_io = io_chain_get(p->io_chain(), STDIN_FILENO);
|
|
stdin_is_directly_redirected = stdin_io && stdin_io->io_mode != io_mode_t::close;
|
|
}
|
|
|
|
streams.stdin_fd = local_builtin_stdin;
|
|
streams.out_is_redirected = has_fd(proc_io_chain, STDOUT_FILENO);
|
|
streams.err_is_redirected = has_fd(proc_io_chain, STDERR_FILENO);
|
|
streams.stdin_is_directly_redirected = stdin_is_directly_redirected;
|
|
streams.io_chain = &proc_io_chain;
|
|
|
|
// Since this may be the foreground job, and since a builtin may execute another
|
|
// foreground job, we need to pretend to suspend this job while running the
|
|
// builtin, in order to avoid a situation where two jobs are running at once.
|
|
//
|
|
// The reason this is done here, and not by the relevant builtins, is that this
|
|
// way, the builtin does not need to know what job it is part of. It could
|
|
// probably figure that out by walking the job list, but it seems more robust to
|
|
// make exec handle things.
|
|
const int fg = j->is_foreground();
|
|
j->set_flag(job_flag_t::FOREGROUND, false);
|
|
|
|
// Note this call may block for a long time, while the builtin performs I/O.
|
|
p->status = builtin_run(parser, j->pgid, p->get_argv(), streams);
|
|
|
|
// Restore the fg flag, which is temporarily set to false during builtin
|
|
// execution so as not to confuse some job-handling builtins.
|
|
j->set_flag(job_flag_t::FOREGROUND, fg);
|
|
|
|
return true; // "success"
|
|
}
|
|
|
|
/// Handle output from a builtin, by printing the contents of builtin_io_streams to the redirections
|
|
/// given in io_chain.
|
|
static bool handle_builtin_output(const std::shared_ptr<job_t> &j, process_t *p,
|
|
io_chain_t *io_chain, const io_streams_t &builtin_io_streams) {
|
|
assert(p->type == INTERNAL_BUILTIN && "Process is not a builtin");
|
|
|
|
const output_stream_t &stdout_stream = builtin_io_streams.out;
|
|
const output_stream_t &stderr_stream = builtin_io_streams.err;
|
|
|
|
// Mark if we discarded output.
|
|
if (stdout_stream.buffer().discarded()) p->status = STATUS_READ_TOO_MUCH;
|
|
|
|
// We will try to elide constructing an internal process. However if the output is going to a
|
|
// real file, we have to do it. For example in `echo -n > file.txt` we proceed to open file.txt
|
|
// even though there is no output, so that it is properly truncated.
|
|
const shared_ptr<io_data_t> stdout_io = io_chain->get_io_for_fd(STDOUT_FILENO);
|
|
const shared_ptr<io_data_t> stderr_io = io_chain->get_io_for_fd(STDERR_FILENO);
|
|
bool must_use_process =
|
|
redirection_is_to_real_file(stdout_io) || redirection_is_to_real_file(stderr_io);
|
|
|
|
// If we are directing output to a buffer, then we can just transfer it directly without needing
|
|
// to write to the bufferfill pipe. Note this is how we handle explicitly separated stdout
|
|
// output (i.e. string split0) which can't really be sent through a pipe.
|
|
// TODO: we're sloppy about handling explicitly separated output.
|
|
// Theoretically we could have explicitly separated output on stdout and also stderr output; in
|
|
// that case we ought to thread the exp-sep output through to the io buffer. We're getting away
|
|
// with this because the only thing that can output exp-sep output is `string split0` which
|
|
// doesn't also produce stderr. Also note that we never send stderr to a buffer, so there's no
|
|
// need for a similar check for stderr.
|
|
bool stdout_done = false;
|
|
if (stdout_io && stdout_io->io_mode == io_mode_t::bufferfill) {
|
|
auto stdout_buffer = static_cast<io_bufferfill_t *>(stdout_io.get())->buffer();
|
|
stdout_buffer->append_from_stream(stdout_stream);
|
|
stdout_done = true;
|
|
}
|
|
|
|
// Figure out any data remaining to write. We may have none in which case we can short-circuit.
|
|
std::string outbuff = stdout_done ? std::string{} : wcs2string(stdout_stream.contents());
|
|
std::string errbuff = wcs2string(stderr_stream.contents());
|
|
|
|
// If we have no redirections for stdout/stderr, just write them directly.
|
|
if (!stdout_io && !stderr_io) {
|
|
bool did_err = false;
|
|
if (write_loop(STDOUT_FILENO, outbuff.data(), outbuff.size()) < 0) {
|
|
if (errno != EPIPE) {
|
|
did_err = true;
|
|
debug(0, "Error while writing to stdout");
|
|
wperror(L"write_loop");
|
|
}
|
|
}
|
|
if (write_loop(STDERR_FILENO, errbuff.data(), errbuff.size()) < 0) {
|
|
if (errno != EPIPE && !did_err) {
|
|
did_err = true;
|
|
debug(0, "Error while writing to stderr");
|
|
wperror(L"write_loop");
|
|
}
|
|
}
|
|
if (did_err) {
|
|
redirect_tty_output(); // workaround glibc bug
|
|
debug(0, "!builtin_io_done and errno != EPIPE");
|
|
show_stackframe(L'E');
|
|
}
|
|
// Clear the buffers to indicate we finished.
|
|
outbuff.clear();
|
|
errbuff.clear();
|
|
}
|
|
|
|
if (!must_use_process && outbuff.empty() && errbuff.empty()) {
|
|
// We do not need to construct a background process.
|
|
// TODO: factor this job-status-setting stuff into a single place.
|
|
p->completed = 1;
|
|
if (p->is_last_in_job) {
|
|
debug(4, L"Set status of job %d (%ls) to %d using short circuit", j->job_id,
|
|
j->preview().c_str(), p->status);
|
|
|
|
int status = p->status;
|
|
proc_set_last_status(j->get_flag(job_flag_t::NEGATE) ? (!status) : status);
|
|
}
|
|
return true;
|
|
} else {
|
|
// Construct and run our background process.
|
|
fflush(stdout);
|
|
fflush(stderr);
|
|
return run_internal_process(p, std::move(outbuff), std::move(errbuff), *io_chain);
|
|
}
|
|
}
|
|
|
|
/// Executes an external command.
|
|
/// \return true on success, false if there is an exec error.
|
|
static bool exec_external_command(env_stack_t &vars, const std::shared_ptr<job_t> &j,
|
|
process_t *p, const io_chain_t &proc_io_chain) {
|
|
assert(p->type == EXTERNAL && "Process is not external");
|
|
// Get argv and envv before we fork.
|
|
null_terminated_array_t<char> argv_array;
|
|
convert_wide_array_to_narrow(p->get_argv_array(), &argv_array);
|
|
|
|
// Convert our IO chain to a dup2 sequence.
|
|
auto dup2s = dup2_list_t::resolve_chain(proc_io_chain);
|
|
if (! dup2s)
|
|
return false;
|
|
|
|
// Ensure that stdin is blocking before we hand it off (see issue #176). It's a
|
|
// little strange that we only do this with stdin and not with stdout or stderr.
|
|
// However in practice, setting or clearing O_NONBLOCK on stdin also sets it for the
|
|
// other two fds, presumably because they refer to the same underlying file
|
|
// (/dev/tty?).
|
|
make_fd_blocking(STDIN_FILENO);
|
|
|
|
const char *const *argv = argv_array.get();
|
|
const char *const *envv = vars.export_arr();
|
|
|
|
std::string actual_cmd_str = wcs2string(p->actual_cmd);
|
|
const char *actual_cmd = actual_cmd_str.c_str();
|
|
const wchar_t *file = reader_current_filename();
|
|
|
|
#if FISH_USE_POSIX_SPAWN
|
|
// Prefer to use posix_spawn, since it's faster on some systems like OS X.
|
|
bool use_posix_spawn = g_use_posix_spawn && can_use_posix_spawn_for_job(j);
|
|
if (use_posix_spawn) {
|
|
g_fork_count++; // spawn counts as a fork+exec
|
|
// Create posix spawn attributes and actions.
|
|
pid_t pid = 0;
|
|
posix_spawnattr_t attr = posix_spawnattr_t();
|
|
posix_spawn_file_actions_t actions = posix_spawn_file_actions_t();
|
|
bool made_it = fork_actions_make_spawn_properties(&attr, &actions, j.get(), *dup2s);
|
|
if (made_it) {
|
|
// We successfully made the attributes and actions; actually call
|
|
// posix_spawn.
|
|
int spawn_ret =
|
|
posix_spawn(&pid, actual_cmd, &actions, &attr, const_cast<char *const *>(argv),
|
|
const_cast<char *const *>(envv));
|
|
|
|
// This usleep can be used to test for various race conditions
|
|
// (https://github.com/fish-shell/fish-shell/issues/360).
|
|
// usleep(10000);
|
|
|
|
if (spawn_ret != 0) {
|
|
safe_report_exec_error(spawn_ret, actual_cmd, argv, envv);
|
|
// Make sure our pid isn't set.
|
|
pid = 0;
|
|
}
|
|
|
|
// Clean up our actions.
|
|
posix_spawn_file_actions_destroy(&actions);
|
|
posix_spawnattr_destroy(&attr);
|
|
}
|
|
|
|
// A 0 pid means we failed to posix_spawn. Since we have no pid, we'll never get
|
|
// told when it's exited, so we have to mark the process as failed.
|
|
debug(4, L"Fork #%d, pid %d: spawn external command '%s' from '%ls'", g_fork_count, pid,
|
|
actual_cmd, file ? file : L"<no file>");
|
|
if (pid == 0) {
|
|
job_mark_process_as_failed(j, p);
|
|
return false;
|
|
}
|
|
|
|
// these are all things do_fork() takes care of normally (for forked processes):
|
|
p->pid = pid;
|
|
on_process_created(j, p->pid);
|
|
|
|
// We explicitly don't call set_child_group() for spawned processes because that
|
|
// a) isn't necessary, and b) causes issues like fish-shell/fish-shell#4715
|
|
|
|
#if defined(__GLIBC__)
|
|
// Unfortunately, using posix_spawn() is not the panacea it would appear to be,
|
|
// glibc has a penchant for using fork() instead of vfork() when posix_spawn() is
|
|
// called, meaning that atomicity is not guaranteed and we can get here before the
|
|
// child group has been set. See discussion here:
|
|
// https://github.com/Microsoft/WSL/issues/2997 And confirmation that this persists
|
|
// past glibc 2.24+ here: https://github.com/fish-shell/fish-shell/issues/4715
|
|
if (j->get_flag(job_flag_t::JOB_CONTROL) && getpgid(p->pid) != j->pgid) {
|
|
set_child_group(j.get(), p->pid);
|
|
}
|
|
#else
|
|
// In do_fork, the pid of the child process is used as the group leader if j->pgid
|
|
// invalid, posix_spawn assigned the new group a pgid equal to its own id if
|
|
// j->pgid was invalid, so this is what we do instead of calling set_child_group
|
|
if (j->pgid == INVALID_PID) {
|
|
j->pgid = pid;
|
|
}
|
|
#endif
|
|
|
|
maybe_assign_terminal(j.get());
|
|
} else
|
|
#endif
|
|
{
|
|
if (!fork_child_for_process(j, p, *dup2s, false, "external command",
|
|
[&] { safe_launch_process(p, actual_cmd, argv, envv); })) {
|
|
return false;
|
|
}
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
/// Execute a block node or function "process".
|
|
/// \p user_ios contains the list of user-specified ios, used so we can avoid stomping on them with
|
|
/// our pipes. \return true on success, false on error.
|
|
static bool exec_block_or_func_process(parser_t &parser, std::shared_ptr<job_t> j, process_t *p,
|
|
const io_chain_t &user_ios, io_chain_t io_chain) {
|
|
assert((p->type == INTERNAL_FUNCTION || p->type == INTERNAL_BLOCK_NODE) &&
|
|
"Unexpected process type");
|
|
|
|
// Create an output buffer if we're piping to another process.
|
|
shared_ptr<io_bufferfill_t> block_output_bufferfill{};
|
|
if (!p->is_last_in_job) {
|
|
// Be careful to handle failure, e.g. too many open fds.
|
|
block_output_bufferfill = io_bufferfill_t::create(user_ios);
|
|
if (!block_output_bufferfill) {
|
|
job_mark_process_as_failed(j, p);
|
|
return false;
|
|
}
|
|
// Teach the job about its bufferfill, and add it to our io chain.
|
|
io_chain.push_back(block_output_bufferfill);
|
|
}
|
|
|
|
if (p->type == INTERNAL_FUNCTION) {
|
|
const wcstring func_name = p->argv0();
|
|
auto props = function_get_properties(func_name);
|
|
if (!props) {
|
|
debug(0, _(L"Unknown function '%ls'"), p->argv0());
|
|
return false;
|
|
}
|
|
|
|
const std::map<wcstring, env_var_t> inherit_vars = function_get_inherit_vars(func_name);
|
|
|
|
function_block_t *fb =
|
|
parser.push_block<function_block_t>(p, func_name, props->shadow_scope);
|
|
function_prepare_environment(parser.vars(), func_name, p->get_argv() + 1, inherit_vars);
|
|
parser.forbid_function(func_name);
|
|
|
|
internal_exec_helper(parser, props->parsed_source, props->body_node, io_chain, j);
|
|
|
|
parser.allow_function();
|
|
parser.pop_block(fb);
|
|
} else {
|
|
assert(p->type == INTERNAL_BLOCK_NODE);
|
|
assert(p->block_node_source && p->internal_block_node && "Process is missing node info");
|
|
internal_exec_helper(parser, p->block_node_source, p->internal_block_node, io_chain, j);
|
|
}
|
|
|
|
int status = proc_get_last_status();
|
|
|
|
// If we have a block output buffer, populate it now.
|
|
if (!block_output_bufferfill) {
|
|
// No buffer, so we exit directly. This means we have to manually set the exit
|
|
// status.
|
|
if (p->is_last_in_job) {
|
|
proc_set_last_status(j->get_flag(job_flag_t::NEGATE) ? (!status) : status);
|
|
}
|
|
p->completed = 1;
|
|
return true;
|
|
}
|
|
assert(block_output_bufferfill && "Must have a block output bufferfiller");
|
|
|
|
// 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);
|
|
auto block_output_buffer = io_bufferfill_t::finish(std::move(block_output_bufferfill));
|
|
|
|
std::string buffer_contents = block_output_buffer->buffer().newline_serialized();
|
|
if (!buffer_contents.empty()) {
|
|
return run_internal_process(p, std::move(buffer_contents), {} /*errdata*/, io_chain);
|
|
} else {
|
|
if (p->is_last_in_job) {
|
|
proc_set_last_status(j->get_flag(job_flag_t::NEGATE) ? (!status) : status);
|
|
}
|
|
p->completed = 1;
|
|
}
|
|
return true;
|
|
}
|
|
|
|
/// Executes a process \p in job \j, using the read pipe \p pipe_current_read.
|
|
/// If the process pipes to a command, the read end of the created pipe is returned in
|
|
/// out_pipe_next_read. \returns true on success, false on exec error.
|
|
static bool exec_process_in_job(parser_t &parser, process_t *p, std::shared_ptr<job_t> j,
|
|
autoclose_fd_t pipe_current_read,
|
|
autoclose_fd_t *out_pipe_next_read, const io_chain_t &all_ios,
|
|
size_t stdout_read_limit) {
|
|
// The pipe this command will write to (if any).
|
|
shared_ptr<io_pipe_t> pipe_write;
|
|
// The pipe this command will read from (if any).
|
|
shared_ptr<io_pipe_t> pipe_read;
|
|
|
|
// See if we need a pipe for the next command.
|
|
const bool pipes_to_next_command = !p->is_last_in_job;
|
|
if (pipes_to_next_command) {
|
|
// Construct our pipes.
|
|
auto local_pipes = make_autoclose_pipes(all_ios);
|
|
if (!local_pipes) {
|
|
debug(1, PIPE_ERROR);
|
|
wperror(L"pipe");
|
|
job_mark_process_as_failed(j, p);
|
|
return false;
|
|
}
|
|
|
|
pipe_write = std::make_shared<io_pipe_t>(p->pipe_write_fd, false /* not input */,
|
|
std::move(local_pipes->write));
|
|
*out_pipe_next_read = std::move(local_pipes->read);
|
|
}
|
|
|
|
// 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.
|
|
|
|
// The IO chain for this process.
|
|
io_chain_t process_net_io_chain = j->block_io_chain();
|
|
if (pipe_write) {
|
|
process_net_io_chain.push_back(pipe_write);
|
|
}
|
|
|
|
// The explicit IO redirections associated with the process.
|
|
process_net_io_chain.append(p->io_chain());
|
|
|
|
// Read pipe goes last.
|
|
if (pipe_current_read.valid()) {
|
|
pipe_read = std::make_shared<io_pipe_t>(STDIN_FILENO, true /* input */,
|
|
std::move(pipe_current_read));
|
|
process_net_io_chain.push_back(pipe_read);
|
|
}
|
|
|
|
// This call is used so the global environment variable array is regenerated, if needed,
|
|
// before the fork. That way, we avoid a lot of duplicate work where EVERY child would need
|
|
// to generate it, since that result would not get written back to the parent. This call
|
|
// could be safely removed, but it would result in slightly lower performance - at least on
|
|
// uniprocessor systems.
|
|
if (p->type == EXTERNAL) {
|
|
// Apply universal barrier so we have the most recent uvar changes
|
|
if (!get_proc_had_barrier()) {
|
|
set_proc_had_barrier(true);
|
|
env_universal_barrier();
|
|
}
|
|
parser.vars().export_arr();
|
|
}
|
|
|
|
// Execute the process.
|
|
p->check_generations_before_launch();
|
|
switch (p->type) {
|
|
case INTERNAL_FUNCTION:
|
|
case INTERNAL_BLOCK_NODE: {
|
|
if (!exec_block_or_func_process(parser, j, p, all_ios, process_net_io_chain)) {
|
|
return false;
|
|
}
|
|
break;
|
|
}
|
|
|
|
case INTERNAL_BUILTIN: {
|
|
io_streams_t builtin_io_streams{stdout_read_limit};
|
|
if (!exec_internal_builtin_proc(parser, j, p, pipe_read.get(), process_net_io_chain,
|
|
builtin_io_streams)) {
|
|
return false;
|
|
}
|
|
if (!handle_builtin_output(j, p, &process_net_io_chain, builtin_io_streams)) {
|
|
return false;
|
|
}
|
|
break;
|
|
}
|
|
|
|
case EXTERNAL: {
|
|
if (!exec_external_command(parser.vars(), j, p, process_net_io_chain)) {
|
|
return false;
|
|
}
|
|
break;
|
|
}
|
|
|
|
case INTERNAL_EXEC: {
|
|
// We should have handled exec up above.
|
|
DIE("INTERNAL_EXEC process found in pipeline, where it should never be. Aborting.");
|
|
break;
|
|
}
|
|
}
|
|
return true;
|
|
}
|
|
|
|
bool exec_job(parser_t &parser, shared_ptr<job_t> j) {
|
|
assert(j && "null job_t passed to exec_job!");
|
|
|
|
// Set to true if something goes wrong while executing the job, in which case the cleanup
|
|
// code will kick in.
|
|
bool exec_error = false;
|
|
|
|
// If fish was invoked with -n or --no-execute, then no_exec will be set and we do nothing.
|
|
if (no_exec) {
|
|
return true;
|
|
}
|
|
|
|
const std::shared_ptr<job_t> parent_job = j->get_parent();
|
|
|
|
// Perhaps inherit our parent's pgid and job control flag.
|
|
if (parent_job && j->processes.front()->type == EXTERNAL) {
|
|
if (parent_job->pgid != INVALID_PID) {
|
|
j->pgid = parent_job->pgid;
|
|
j->set_flag(job_flag_t::JOB_CONTROL, true);
|
|
}
|
|
}
|
|
|
|
size_t stdout_read_limit = 0;
|
|
const io_chain_t all_ios = j->all_io_redirections();
|
|
for (auto &io : all_ios) {
|
|
if ((io->io_mode == io_mode_t::bufferfill)) {
|
|
// The read limit is dictated by the last bufferfill.
|
|
const auto *bf = static_cast<io_bufferfill_t *>(io.get());
|
|
stdout_read_limit = bf->buffer()->read_limit();
|
|
}
|
|
}
|
|
|
|
if (j->processes.front()->type == INTERNAL_EXEC) {
|
|
internal_exec(parser.vars(), j.get(), all_ios);
|
|
// internal_exec only returns if it failed to set up redirections.
|
|
// In case of an successful exec, this code is not reached.
|
|
bool status = j->get_flag(job_flag_t::NEGATE) ? 0 : 1;
|
|
proc_set_last_status(status);
|
|
return false;
|
|
}
|
|
|
|
// 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)
|
|
//
|
|
autoclose_fd_t pipe_next_read;
|
|
for (const auto &unique_p : j->processes) {
|
|
autoclose_fd_t current_read = std::move(pipe_next_read);
|
|
if (!exec_process_in_job(parser, unique_p.get(), j, std::move(current_read),
|
|
&pipe_next_read, all_ios, stdout_read_limit)) {
|
|
exec_error = true;
|
|
break;
|
|
}
|
|
}
|
|
pipe_next_read.close();
|
|
|
|
debug(3, L"Created job %d from command '%ls' with pgrp %d", j->job_id, j->command_wcstr(),
|
|
j->pgid);
|
|
|
|
j->set_flag(job_flag_t::CONSTRUCTED, true);
|
|
if (!j->is_foreground()) {
|
|
parser.vars().set_one(L"last_pid", ENV_GLOBAL, to_string(j->pgid));
|
|
}
|
|
|
|
if (exec_error) {
|
|
return false;
|
|
}
|
|
|
|
j->continue_job(false);
|
|
return true;
|
|
}
|
|
|
|
static int exec_subshell_internal(const wcstring &cmd, parser_t &parser, wcstring_list_t *lst,
|
|
bool apply_exit_status, bool is_subcmd) {
|
|
ASSERT_IS_MAIN_THREAD();
|
|
bool prev_subshell = is_subshell;
|
|
const int prev_status = proc_get_last_status();
|
|
bool split_output = false;
|
|
|
|
const auto ifs = parser.vars().get(L"IFS");
|
|
if (!ifs.missing_or_empty()) {
|
|
split_output = true;
|
|
}
|
|
|
|
is_subshell = true;
|
|
int subcommand_status = -1; // assume the worst
|
|
|
|
// IO buffer creation may fail (e.g. if we have too many open files to make a pipe), so this may
|
|
// be null.
|
|
size_t read_limit = is_subcmd ? read_byte_limit : 0;
|
|
std::shared_ptr<io_buffer_t> buffer;
|
|
if (auto bufferfill = io_bufferfill_t::create(io_chain_t{}, read_limit)) {
|
|
parser_t &parser = parser_t::principal_parser();
|
|
if (parser.eval(cmd, io_chain_t{bufferfill}, SUBST) == 0) {
|
|
subcommand_status = proc_get_last_status();
|
|
}
|
|
buffer = io_bufferfill_t::finish(std::move(bufferfill));
|
|
}
|
|
|
|
if (buffer && buffer->buffer().discarded()) subcommand_status = STATUS_READ_TOO_MUCH;
|
|
|
|
// If the caller asked us to preserve the exit status, restore the old status. Otherwise set the
|
|
// status of the subcommand.
|
|
proc_set_last_status(apply_exit_status ? subcommand_status : prev_status);
|
|
is_subshell = prev_subshell;
|
|
|
|
if (lst == NULL || !buffer) {
|
|
return subcommand_status;
|
|
}
|
|
// Walk over all the elements.
|
|
for (const auto &elem : buffer->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_output) {
|
|
const char *cursor = begin;
|
|
while (cursor < end) {
|
|
// Look for the next separator.
|
|
const char *stop = (const char *)memchr(cursor, '\n', end - cursor);
|
|
const bool hit_separator = (stop != NULL);
|
|
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));
|
|
}
|
|
}
|
|
|
|
return subcommand_status;
|
|
}
|
|
|
|
int exec_subshell(const wcstring &cmd, parser_t &parser, std::vector<wcstring> &outputs,
|
|
bool apply_exit_status, bool is_subcmd) {
|
|
ASSERT_IS_MAIN_THREAD();
|
|
return exec_subshell_internal(cmd, parser, &outputs, apply_exit_status, is_subcmd);
|
|
}
|
|
|
|
int exec_subshell(const wcstring &cmd, parser_t &parser, bool apply_exit_status, bool is_subcmd) {
|
|
ASSERT_IS_MAIN_THREAD();
|
|
return exec_subshell_internal(cmd, parser, NULL, apply_exit_status, is_subcmd);
|
|
}
|