fish-shell/src/redirection.cpp

#include "config.h"  // IWYU pragma: keep

#include "redirection.h"

#include <errno.h>
#include <fcntl.h>

#include <memory>

#include "io.h"
#include "wutil.h"

dup2_list_t::~dup2_list_t() = default;

maybe_t<int> redirection_spec_t::get_target_as_fd() const {
    errno = 0;
    int result = fish_wcstoi(target.c_str());
    if (errno || result < 0) return none();
    return result;
}

int redirection_spec_t::oflags() const {
    switch (mode) {
        case redirection_mode_t::append:
            return O_CREAT | O_APPEND | O_WRONLY;
        case redirection_mode_t::overwrite:
            return O_CREAT | O_WRONLY | O_TRUNC;
        case redirection_mode_t::noclob:
            return O_CREAT | O_EXCL | O_WRONLY;
        case redirection_mode_t::input:
            return O_RDONLY;
        case redirection_mode_t::fd:
        default:
            DIE("Not a file redirection");
    }
}

dup2_list_t dup2_list_t::resolve_chain(const io_chain_t &io_chain) {
    ASSERT_IS_NOT_FORKED_CHILD();
    dup2_list_t result;
    for (const auto &io : io_chain) {
        if (io->source_fd < 0) {
            result.add_close(io->fd);
        } else {
            result.add_dup2(io->source_fd, io->fd);
        }
    }
    return result;
}

int dup2_list_t::fd_for_target_fd(int target) const {
    // Paranoia.
    if (target < 0) {
        return target;
    }
    // Note we can simply walk our action list backwards, looking for src -> target dups.
    int cursor = target;
    for (auto iter = actions_.rbegin(); iter != actions_.rend(); ++iter) {
        if (iter->target == cursor) {
            // cursor is replaced by iter->src
            cursor = iter->src;
        } else if (iter->src == cursor && iter->target < 0) {
            // cursor is closed.
            cursor = -1;
            break;
        }
    }
    return cursor;
}