run-command.c

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#include "cache.h"
#include "run-command.h"
#include "exec_cmd.h"

static inline void close_pair(int fd[2])
{
    close(fd[0]);
    close(fd[1]);
}

static inline void dup_devnull(int to)
{
    int fd = open("/dev/null", O_RDWR);
    dup2(fd, to);
    close(fd);
}

int start_command(struct child_process *cmd)
{
    int need_in, need_out, need_err;
    int fdin[2], fdout[2], fderr[2];

    /*
     * In case of errors we must keep the promise to close FDs
     * that have been passed in via ->in and ->out.
     */

    need_in = !cmd->no_stdin && cmd->in < 0;
    if (need_in) {
        if (pipe(fdin) < 0) {
            if (cmd->out > 0)
                close(cmd->out);
            return -ERR_RUN_COMMAND_PIPE;
        }
        cmd->in = fdin[1];
    }

    need_out = !cmd->no_stdout
        && !cmd->stdout_to_stderr
        && cmd->out < 0;
    if (need_out) {
        if (pipe(fdout) < 0) {
            if (need_in)
                close_pair(fdin);
            else if (cmd->in)
                close(cmd->in);
            return -ERR_RUN_COMMAND_PIPE;
        }
        cmd->out = fdout[0];
    }

    need_err = !cmd->no_stderr && cmd->err < 0;
    if (need_err) {
        if (pipe(fderr) < 0) {
            if (need_in)
                close_pair(fdin);
            else if (cmd->in)
                close(cmd->in);
            if (need_out)
                close_pair(fdout);
            else if (cmd->out)
                close(cmd->out);
            return -ERR_RUN_COMMAND_PIPE;
        }
        cmd->err = fderr[0];
    }

    fflush(NULL);
    cmd->pid = fork();
    if (!cmd->pid) {
        if (cmd->no_stdin)
            dup_devnull(0);
        else if (need_in) {
            dup2(fdin[0], 0);
            close_pair(fdin);
        } else if (cmd->in) {
            dup2(cmd->in, 0);
            close(cmd->in);
        }

        if (cmd->no_stderr)
            dup_devnull(2);
        else if (need_err) {
            dup2(fderr[1], 2);
            close_pair(fderr);
        }

        if (cmd->no_stdout)
            dup_devnull(1);
        else if (cmd->stdout_to_stderr)
            dup2(2, 1);
        else if (need_out) {
            dup2(fdout[1], 1);
            close_pair(fdout);
        } else if (cmd->out > 1) {
            dup2(cmd->out, 1);
            close(cmd->out);
        }

        if (cmd->dir && chdir(cmd->dir))
            die("exec %s: cd to %s failed (%s)", cmd->argv[0],
                cmd->dir, strerror(errno));
        if (cmd->env) {
            for (; *cmd->env; cmd->env++) {
                if (strchr(*cmd->env, '='))
                    putenv((char*)*cmd->env);
                else
                    unsetenv(*cmd->env);
            }
        }
        if (cmd->preexec_cb)
            cmd->preexec_cb();
        if (cmd->perf_cmd) {
            execv_perf_cmd(cmd->argv);
        } else {
            execvp(cmd->argv[0], (char *const*) cmd->argv);
        }
        exit(127);
    }

    if (cmd->pid < 0) {
        int err = errno;
        if (need_in)
            close_pair(fdin);
        else if (cmd->in)
            close(cmd->in);
        if (need_out)
            close_pair(fdout);
        else if (cmd->out)
            close(cmd->out);
        if (need_err)
            close_pair(fderr);
        return err == ENOENT ?
            -ERR_RUN_COMMAND_EXEC :
            -ERR_RUN_COMMAND_FORK;
    }

    if (need_in)
        close(fdin[0]);
    else if (cmd->in)
        close(cmd->in);

    if (need_out)
        close(fdout[1]);
    else if (cmd->out)
        close(cmd->out);

    if (need_err)
        close(fderr[1]);

    return 0;
}

static int wait_or_whine(pid_t pid)
{
    for (;;) {
        int status, code;
        pid_t waiting = waitpid(pid, &status, 0);

        if (waiting < 0) {
            if (errno == EINTR)
                continue;
            error("waitpid failed (%s)", strerror(errno));
            return -ERR_RUN_COMMAND_WAITPID;
        }
        if (waiting != pid)
            return -ERR_RUN_COMMAND_WAITPID_WRONG_PID;
        if (WIFSIGNALED(status))
            return -ERR_RUN_COMMAND_WAITPID_SIGNAL;

        if (!WIFEXITED(status))
            return -ERR_RUN_COMMAND_WAITPID_NOEXIT;
        code = WEXITSTATUS(status);
        switch (code) {
        case 127:
            return -ERR_RUN_COMMAND_EXEC;
        case 0:
            return 0;
        default:
            return -code;
        }
    }
}

int finish_command(struct child_process *cmd)
{
    return wait_or_whine(cmd->pid);
}

int run_command(struct child_process *cmd)
{
    int code = start_command(cmd);
    if (code)
        return code;
    return finish_command(cmd);
}

static void prepare_run_command_v_opt(struct child_process *cmd,
                      const char **argv,
                      int opt)
{
    memset(cmd, 0, sizeof(*cmd));
    cmd->argv = argv;
    cmd->no_stdin = opt & RUN_COMMAND_NO_STDIN ? 1 : 0;
    cmd->perf_cmd = opt & RUN_PERF_CMD ? 1 : 0;
    cmd->stdout_to_stderr = opt & RUN_COMMAND_STDOUT_TO_STDERR ? 1 : 0;
}

int run_command_v_opt(const char **argv, int opt)
{
    struct child_process cmd;
    prepare_run_command_v_opt(&cmd, argv, opt);
    return run_command(&cmd);
}