mirror of
https://github.com/git/git
synced 2024-08-28 20:20:07 +00:00
![Johannes Sixt](/assets/img/avatar_default.png)
The motivation for this change is that system call failures are serious errors that should be reported to the user, but only few callers took the burden to decode the error codes that the functions returned into error messages. If at all, then only an unspecific error message was given. A prominent example is this: $ git upload-pack . | : fatal: unable to run 'git-upload-pack' In this example, git-upload-pack, the external command invoked through the git wrapper, dies due to SIGPIPE, but the git wrapper does not bother to report the real cause. In fact, this very error message is copied to the syslog if git-daemon's client aborts the connection early. With this change, system call failures are reported immediately after the failure and only a generic failure code is returned to the caller. In the above example the error is now to the point: $ git upload-pack . | : error: git-upload-pack died of signal Note that there is no error report if the invoked program terminated with a non-zero exit code, because it is reasonable to expect that the invoked program has already reported an error. (But many run_command call sites nevertheless write a generic error message.) There was one special return code that was used to identify the case where run_command failed because the requested program could not be exec'd. This special case is now treated like a system call failure with errno set to ENOENT. No error is reported in this case, because the call site in git.c expects this as a normal result. Therefore, the callers that carefully decoded the return value still check for this condition. Signed-off-by: Johannes Sixt <j6t@kdbg.org> Signed-off-by: Junio C Hamano <gitster@pobox.com>
402 lines
8.1 KiB
C
402 lines
8.1 KiB
C
#include "cache.h"
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#include "run-command.h"
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#include "exec_cmd.h"
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static inline void close_pair(int fd[2])
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{
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close(fd[0]);
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close(fd[1]);
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}
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static inline void dup_devnull(int to)
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{
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int fd = open("/dev/null", O_RDWR);
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dup2(fd, to);
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close(fd);
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}
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int start_command(struct child_process *cmd)
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{
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int need_in, need_out, need_err;
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int fdin[2], fdout[2], fderr[2];
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int failed_errno;
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/*
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* In case of errors we must keep the promise to close FDs
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* that have been passed in via ->in and ->out.
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*/
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need_in = !cmd->no_stdin && cmd->in < 0;
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if (need_in) {
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if (pipe(fdin) < 0) {
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failed_errno = errno;
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if (cmd->out > 0)
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close(cmd->out);
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goto fail_pipe;
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}
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cmd->in = fdin[1];
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}
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need_out = !cmd->no_stdout
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&& !cmd->stdout_to_stderr
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&& cmd->out < 0;
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if (need_out) {
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if (pipe(fdout) < 0) {
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failed_errno = errno;
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if (need_in)
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close_pair(fdin);
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else if (cmd->in)
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close(cmd->in);
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goto fail_pipe;
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}
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cmd->out = fdout[0];
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}
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need_err = !cmd->no_stderr && cmd->err < 0;
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if (need_err) {
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if (pipe(fderr) < 0) {
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failed_errno = errno;
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if (need_in)
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close_pair(fdin);
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else if (cmd->in)
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close(cmd->in);
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if (need_out)
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close_pair(fdout);
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else if (cmd->out)
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close(cmd->out);
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fail_pipe:
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error("cannot create pipe for %s: %s",
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cmd->argv[0], strerror(failed_errno));
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errno = failed_errno;
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return -1;
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}
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cmd->err = fderr[0];
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}
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trace_argv_printf(cmd->argv, "trace: run_command:");
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#ifndef __MINGW32__
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fflush(NULL);
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cmd->pid = fork();
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if (!cmd->pid) {
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if (cmd->no_stdin)
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dup_devnull(0);
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else if (need_in) {
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dup2(fdin[0], 0);
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close_pair(fdin);
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} else if (cmd->in) {
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dup2(cmd->in, 0);
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close(cmd->in);
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}
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if (cmd->no_stderr)
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dup_devnull(2);
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else if (need_err) {
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dup2(fderr[1], 2);
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close_pair(fderr);
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}
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if (cmd->no_stdout)
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dup_devnull(1);
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else if (cmd->stdout_to_stderr)
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dup2(2, 1);
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else if (need_out) {
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dup2(fdout[1], 1);
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close_pair(fdout);
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} else if (cmd->out > 1) {
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dup2(cmd->out, 1);
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close(cmd->out);
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}
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if (cmd->dir && chdir(cmd->dir))
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die("exec %s: cd to %s failed (%s)", cmd->argv[0],
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cmd->dir, strerror(errno));
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if (cmd->env) {
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for (; *cmd->env; cmd->env++) {
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if (strchr(*cmd->env, '='))
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putenv((char *)*cmd->env);
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else
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unsetenv(*cmd->env);
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}
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}
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if (cmd->preexec_cb)
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cmd->preexec_cb();
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if (cmd->git_cmd) {
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execv_git_cmd(cmd->argv);
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} else {
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execvp(cmd->argv[0], (char *const*) cmd->argv);
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}
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trace_printf("trace: exec '%s' failed: %s\n", cmd->argv[0],
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strerror(errno));
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exit(127);
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}
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if (cmd->pid < 0)
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error("cannot fork() for %s: %s", cmd->argv[0],
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strerror(failed_errno = errno));
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#else
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int s0 = -1, s1 = -1, s2 = -1; /* backups of stdin, stdout, stderr */
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const char **sargv = cmd->argv;
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char **env = environ;
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if (cmd->no_stdin) {
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s0 = dup(0);
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dup_devnull(0);
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} else if (need_in) {
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s0 = dup(0);
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dup2(fdin[0], 0);
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} else if (cmd->in) {
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s0 = dup(0);
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dup2(cmd->in, 0);
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}
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if (cmd->no_stderr) {
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s2 = dup(2);
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dup_devnull(2);
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} else if (need_err) {
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s2 = dup(2);
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dup2(fderr[1], 2);
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}
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if (cmd->no_stdout) {
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s1 = dup(1);
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dup_devnull(1);
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} else if (cmd->stdout_to_stderr) {
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s1 = dup(1);
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dup2(2, 1);
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} else if (need_out) {
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s1 = dup(1);
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dup2(fdout[1], 1);
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} else if (cmd->out > 1) {
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s1 = dup(1);
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dup2(cmd->out, 1);
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}
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if (cmd->dir)
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die("chdir in start_command() not implemented");
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if (cmd->env) {
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env = copy_environ();
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for (; *cmd->env; cmd->env++)
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env = env_setenv(env, *cmd->env);
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}
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if (cmd->git_cmd) {
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cmd->argv = prepare_git_cmd(cmd->argv);
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}
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cmd->pid = mingw_spawnvpe(cmd->argv[0], cmd->argv, env);
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failed_errno = errno;
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if (cmd->pid < 0 && errno != ENOENT)
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error("cannot spawn %s: %s", cmd->argv[0], strerror(errno));
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if (cmd->env)
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free_environ(env);
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if (cmd->git_cmd)
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free(cmd->argv);
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cmd->argv = sargv;
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if (s0 >= 0)
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dup2(s0, 0), close(s0);
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if (s1 >= 0)
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dup2(s1, 1), close(s1);
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if (s2 >= 0)
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dup2(s2, 2), close(s2);
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#endif
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if (cmd->pid < 0) {
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if (need_in)
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close_pair(fdin);
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else if (cmd->in)
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close(cmd->in);
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if (need_out)
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close_pair(fdout);
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else if (cmd->out)
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close(cmd->out);
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if (need_err)
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close_pair(fderr);
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errno = failed_errno;
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return -1;
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}
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if (need_in)
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close(fdin[0]);
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else if (cmd->in)
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close(cmd->in);
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if (need_out)
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close(fdout[1]);
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else if (cmd->out)
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close(cmd->out);
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if (need_err)
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close(fderr[1]);
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return 0;
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}
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static int wait_or_whine(pid_t pid, const char *argv0)
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{
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int status, code = -1;
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pid_t waiting;
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int failed_errno = 0;
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while ((waiting = waitpid(pid, &status, 0)) < 0 && errno == EINTR)
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; /* nothing */
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if (waiting < 0) {
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failed_errno = errno;
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error("waitpid for %s failed: %s", argv0, strerror(errno));
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} else if (waiting != pid) {
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error("waitpid is confused (%s)", argv0);
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} else if (WIFSIGNALED(status)) {
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error("%s died of signal", argv0);
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} else if (WIFEXITED(status)) {
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code = WEXITSTATUS(status);
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/*
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* Convert special exit code when execvp failed.
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*/
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if (code == 127) {
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code = -1;
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failed_errno = ENOENT;
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}
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} else {
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error("waitpid is confused (%s)", argv0);
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}
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errno = failed_errno;
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return code;
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}
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int finish_command(struct child_process *cmd)
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{
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return wait_or_whine(cmd->pid, cmd->argv[0]);
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}
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int run_command(struct child_process *cmd)
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{
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int code = start_command(cmd);
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if (code)
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return code;
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return finish_command(cmd);
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}
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static void prepare_run_command_v_opt(struct child_process *cmd,
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const char **argv,
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int opt)
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{
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memset(cmd, 0, sizeof(*cmd));
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cmd->argv = argv;
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cmd->no_stdin = opt & RUN_COMMAND_NO_STDIN ? 1 : 0;
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cmd->git_cmd = opt & RUN_GIT_CMD ? 1 : 0;
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cmd->stdout_to_stderr = opt & RUN_COMMAND_STDOUT_TO_STDERR ? 1 : 0;
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}
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int run_command_v_opt(const char **argv, int opt)
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{
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struct child_process cmd;
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prepare_run_command_v_opt(&cmd, argv, opt);
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return run_command(&cmd);
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}
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int run_command_v_opt_cd_env(const char **argv, int opt, const char *dir, const char *const *env)
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{
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struct child_process cmd;
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prepare_run_command_v_opt(&cmd, argv, opt);
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cmd.dir = dir;
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cmd.env = env;
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return run_command(&cmd);
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}
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#ifdef __MINGW32__
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static __stdcall unsigned run_thread(void *data)
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{
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struct async *async = data;
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return async->proc(async->fd_for_proc, async->data);
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}
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#endif
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int start_async(struct async *async)
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{
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int pipe_out[2];
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if (pipe(pipe_out) < 0)
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return error("cannot create pipe: %s", strerror(errno));
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async->out = pipe_out[0];
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#ifndef __MINGW32__
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/* Flush stdio before fork() to avoid cloning buffers */
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fflush(NULL);
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async->pid = fork();
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if (async->pid < 0) {
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error("fork (async) failed: %s", strerror(errno));
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close_pair(pipe_out);
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return -1;
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}
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if (!async->pid) {
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close(pipe_out[0]);
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exit(!!async->proc(pipe_out[1], async->data));
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}
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close(pipe_out[1]);
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#else
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async->fd_for_proc = pipe_out[1];
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async->tid = (HANDLE) _beginthreadex(NULL, 0, run_thread, async, 0, NULL);
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if (!async->tid) {
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error("cannot create thread: %s", strerror(errno));
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close_pair(pipe_out);
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return -1;
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}
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#endif
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return 0;
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}
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int finish_async(struct async *async)
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{
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#ifndef __MINGW32__
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int ret = wait_or_whine(async->pid, "child process");
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#else
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DWORD ret = 0;
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if (WaitForSingleObject(async->tid, INFINITE) != WAIT_OBJECT_0)
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ret = error("waiting for thread failed: %lu", GetLastError());
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else if (!GetExitCodeThread(async->tid, &ret))
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ret = error("cannot get thread exit code: %lu", GetLastError());
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CloseHandle(async->tid);
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#endif
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return ret;
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}
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int run_hook(const char *index_file, const char *name, ...)
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{
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struct child_process hook;
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const char **argv = NULL, *env[2];
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char index[PATH_MAX];
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va_list args;
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int ret;
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size_t i = 0, alloc = 0;
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if (access(git_path("hooks/%s", name), X_OK) < 0)
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return 0;
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va_start(args, name);
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ALLOC_GROW(argv, i + 1, alloc);
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argv[i++] = git_path("hooks/%s", name);
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while (argv[i-1]) {
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ALLOC_GROW(argv, i + 1, alloc);
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argv[i++] = va_arg(args, const char *);
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}
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va_end(args);
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memset(&hook, 0, sizeof(hook));
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hook.argv = argv;
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hook.no_stdin = 1;
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hook.stdout_to_stderr = 1;
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if (index_file) {
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snprintf(index, sizeof(index), "GIT_INDEX_FILE=%s", index_file);
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env[0] = index;
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env[1] = NULL;
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hook.env = env;
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}
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ret = run_command(&hook);
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free(argv);
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return ret;
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}
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