git/run-command.c
bert Dvornik fc012c2810 start_command: close cmd->err descriptor when fork/spawn fails
Fix the problem where the cmd->err passed into start_command wasn't
being properly closed when certain types of errors occurr.  (Compare
the affected code with the clean shutdown code later in the function.)

On Windows, this problem would be triggered if mingw_spawnvpe()
failed, which would happen if the command to be executed was malformed
(e.g. a text file that didn't start with a #! line).  If cmd->err was
a pipe, the failure to close it could result in a hang while the other
side was waiting (forever) for either input or pipe close, e.g. while
trying to shove the output into the side band.  On msysGit, this
problem was causing a hang in t5516-fetch-push.

[J6t: With a slight adjustment of the test case, the hang is also
observed on Linux.]

Signed-off-by: bert Dvornik <dvornik+git@gmail.com>
Signed-off-by: Johannes Sixt <j6t@kdbg.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2010-05-20 16:11:29 -07:00

603 lines
13 KiB
C

#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]);
}
#ifndef WIN32
static inline void dup_devnull(int to)
{
int fd = open("/dev/null", O_RDWR);
dup2(fd, to);
close(fd);
}
#endif
static const char **prepare_shell_cmd(const char **argv)
{
int argc, nargc = 0;
const char **nargv;
for (argc = 0; argv[argc]; argc++)
; /* just counting */
/* +1 for NULL, +3 for "sh -c" plus extra $0 */
nargv = xmalloc(sizeof(*nargv) * (argc + 1 + 3));
if (argc < 1)
die("BUG: shell command is empty");
if (strcspn(argv[0], "|&;<>()$`\\\"' \t\n*?[#~=%") != strlen(argv[0])) {
nargv[nargc++] = "sh";
nargv[nargc++] = "-c";
if (argc < 2)
nargv[nargc++] = argv[0];
else {
struct strbuf arg0 = STRBUF_INIT;
strbuf_addf(&arg0, "%s \"$@\"", argv[0]);
nargv[nargc++] = strbuf_detach(&arg0, NULL);
}
}
for (argc = 0; argv[argc]; argc++)
nargv[nargc++] = argv[argc];
nargv[nargc] = NULL;
return nargv;
}
#ifndef WIN32
static int execv_shell_cmd(const char **argv)
{
const char **nargv = prepare_shell_cmd(argv);
trace_argv_printf(nargv, "trace: exec:");
execvp(nargv[0], (char **)nargv);
free(nargv);
return -1;
}
#endif
#ifndef WIN32
static int child_err = 2;
static int child_notifier = -1;
static void notify_parent(void)
{
ssize_t unused;
unused = write(child_notifier, "", 1);
}
static NORETURN void die_child(const char *err, va_list params)
{
char msg[4096];
ssize_t unused;
int len = vsnprintf(msg, sizeof(msg), err, params);
if (len > sizeof(msg))
len = sizeof(msg);
unused = write(child_err, "fatal: ", 7);
unused = write(child_err, msg, len);
unused = write(child_err, "\n", 1);
exit(128);
}
static inline void set_cloexec(int fd)
{
int flags = fcntl(fd, F_GETFD);
if (flags >= 0)
fcntl(fd, F_SETFD, flags | FD_CLOEXEC);
}
#endif
static int wait_or_whine(pid_t pid, const char *argv0, int silent_exec_failure)
{
int status, code = -1;
pid_t waiting;
int failed_errno = 0;
while ((waiting = waitpid(pid, &status, 0)) < 0 && errno == EINTR)
; /* nothing */
if (waiting < 0) {
failed_errno = errno;
error("waitpid for %s failed: %s", argv0, strerror(errno));
} else if (waiting != pid) {
error("waitpid is confused (%s)", argv0);
} else if (WIFSIGNALED(status)) {
code = WTERMSIG(status);
error("%s died of signal %d", argv0, code);
/*
* This return value is chosen so that code & 0xff
* mimics the exit code that a POSIX shell would report for
* a program that died from this signal.
*/
code -= 128;
} else if (WIFEXITED(status)) {
code = WEXITSTATUS(status);
/*
* Convert special exit code when execvp failed.
*/
if (code == 127) {
code = -1;
failed_errno = ENOENT;
if (!silent_exec_failure)
error("cannot run %s: %s", argv0,
strerror(ENOENT));
}
} else {
error("waitpid is confused (%s)", argv0);
}
errno = failed_errno;
return code;
}
int start_command(struct child_process *cmd)
{
int need_in, need_out, need_err;
int fdin[2], fdout[2], fderr[2];
int failed_errno = failed_errno;
/*
* 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) {
failed_errno = errno;
if (cmd->out > 0)
close(cmd->out);
goto fail_pipe;
}
cmd->in = fdin[1];
}
need_out = !cmd->no_stdout
&& !cmd->stdout_to_stderr
&& cmd->out < 0;
if (need_out) {
if (pipe(fdout) < 0) {
failed_errno = errno;
if (need_in)
close_pair(fdin);
else if (cmd->in)
close(cmd->in);
goto fail_pipe;
}
cmd->out = fdout[0];
}
need_err = !cmd->no_stderr && cmd->err < 0;
if (need_err) {
if (pipe(fderr) < 0) {
failed_errno = 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);
fail_pipe:
error("cannot create pipe for %s: %s",
cmd->argv[0], strerror(failed_errno));
errno = failed_errno;
return -1;
}
cmd->err = fderr[0];
}
trace_argv_printf(cmd->argv, "trace: run_command:");
#ifndef WIN32
{
int notify_pipe[2];
if (pipe(notify_pipe))
notify_pipe[0] = notify_pipe[1] = -1;
fflush(NULL);
cmd->pid = fork();
if (!cmd->pid) {
/*
* Redirect the channel to write syscall error messages to
* before redirecting the process's stderr so that all die()
* in subsequent call paths use the parent's stderr.
*/
if (cmd->no_stderr || need_err) {
child_err = dup(2);
set_cloexec(child_err);
}
set_die_routine(die_child);
close(notify_pipe[0]);
set_cloexec(notify_pipe[1]);
child_notifier = notify_pipe[1];
atexit(notify_parent);
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);
} else if (cmd->err > 1) {
dup2(cmd->err, 2);
close(cmd->err);
}
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_errno("exec '%s': cd to '%s' failed", cmd->argv[0],
cmd->dir);
if (cmd->env) {
for (; *cmd->env; cmd->env++) {
if (strchr(*cmd->env, '='))
putenv((char *)*cmd->env);
else
unsetenv(*cmd->env);
}
}
if (cmd->preexec_cb) {
/*
* We cannot predict what the pre-exec callback does.
* Forgo parent notification.
*/
close(child_notifier);
child_notifier = -1;
cmd->preexec_cb();
}
if (cmd->git_cmd) {
execv_git_cmd(cmd->argv);
} else if (cmd->use_shell) {
execv_shell_cmd(cmd->argv);
} else {
execvp(cmd->argv[0], (char *const*) cmd->argv);
}
/*
* Do not check for cmd->silent_exec_failure; the parent
* process will check it when it sees this exit code.
*/
if (errno == ENOENT)
exit(127);
else
die_errno("cannot exec '%s'", cmd->argv[0]);
}
if (cmd->pid < 0)
error("cannot fork() for %s: %s", cmd->argv[0],
strerror(failed_errno = errno));
/*
* Wait for child's execvp. If the execvp succeeds (or if fork()
* failed), EOF is seen immediately by the parent. Otherwise, the
* child process sends a single byte.
* Note that use of this infrastructure is completely advisory,
* therefore, we keep error checks minimal.
*/
close(notify_pipe[1]);
if (read(notify_pipe[0], &notify_pipe[1], 1) == 1) {
/*
* At this point we know that fork() succeeded, but execvp()
* failed. Errors have been reported to our stderr.
*/
wait_or_whine(cmd->pid, cmd->argv[0],
cmd->silent_exec_failure);
failed_errno = errno;
cmd->pid = -1;
}
close(notify_pipe[0]);
}
#else
{
int fhin = 0, fhout = 1, fherr = 2;
const char **sargv = cmd->argv;
char **env = environ;
if (cmd->no_stdin)
fhin = open("/dev/null", O_RDWR);
else if (need_in)
fhin = dup(fdin[0]);
else if (cmd->in)
fhin = dup(cmd->in);
if (cmd->no_stderr)
fherr = open("/dev/null", O_RDWR);
else if (need_err)
fherr = dup(fderr[1]);
else if (cmd->err > 2)
fherr = dup(cmd->err);
if (cmd->no_stdout)
fhout = open("/dev/null", O_RDWR);
else if (cmd->stdout_to_stderr)
fhout = dup(fherr);
else if (need_out)
fhout = dup(fdout[1]);
else if (cmd->out > 1)
fhout = dup(cmd->out);
if (cmd->env)
env = make_augmented_environ(cmd->env);
if (cmd->git_cmd) {
cmd->argv = prepare_git_cmd(cmd->argv);
} else if (cmd->use_shell) {
cmd->argv = prepare_shell_cmd(cmd->argv);
}
cmd->pid = mingw_spawnvpe(cmd->argv[0], cmd->argv, env, cmd->dir,
fhin, fhout, fherr);
failed_errno = errno;
if (cmd->pid < 0 && (!cmd->silent_exec_failure || errno != ENOENT))
error("cannot spawn %s: %s", cmd->argv[0], strerror(errno));
if (cmd->env)
free_environ(env);
if (cmd->git_cmd)
free(cmd->argv);
cmd->argv = sargv;
if (fhin != 0)
close(fhin);
if (fhout != 1)
close(fhout);
if (fherr != 2)
close(fherr);
}
#endif
if (cmd->pid < 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);
if (need_err)
close_pair(fderr);
else if (cmd->err)
close(cmd->err);
errno = failed_errno;
return -1;
}
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]);
else if (cmd->err)
close(cmd->err);
return 0;
}
int finish_command(struct child_process *cmd)
{
return wait_or_whine(cmd->pid, cmd->argv[0], cmd->silent_exec_failure);
}
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->git_cmd = opt & RUN_GIT_CMD ? 1 : 0;
cmd->stdout_to_stderr = opt & RUN_COMMAND_STDOUT_TO_STDERR ? 1 : 0;
cmd->silent_exec_failure = opt & RUN_SILENT_EXEC_FAILURE ? 1 : 0;
cmd->use_shell = opt & RUN_USING_SHELL ? 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);
}
int run_command_v_opt_cd_env(const char **argv, int opt, const char *dir, const char *const *env)
{
struct child_process cmd;
prepare_run_command_v_opt(&cmd, argv, opt);
cmd.dir = dir;
cmd.env = env;
return run_command(&cmd);
}
#ifdef WIN32
static unsigned __stdcall run_thread(void *data)
{
struct async *async = data;
return async->proc(async->proc_in, async->proc_out, async->data);
}
#endif
int start_async(struct async *async)
{
int need_in, need_out;
int fdin[2], fdout[2];
int proc_in, proc_out;
need_in = async->in < 0;
if (need_in) {
if (pipe(fdin) < 0) {
if (async->out > 0)
close(async->out);
return error("cannot create pipe: %s", strerror(errno));
}
async->in = fdin[1];
}
need_out = async->out < 0;
if (need_out) {
if (pipe(fdout) < 0) {
if (need_in)
close_pair(fdin);
else if (async->in)
close(async->in);
return error("cannot create pipe: %s", strerror(errno));
}
async->out = fdout[0];
}
if (need_in)
proc_in = fdin[0];
else if (async->in)
proc_in = async->in;
else
proc_in = -1;
if (need_out)
proc_out = fdout[1];
else if (async->out)
proc_out = async->out;
else
proc_out = -1;
#ifndef WIN32
/* Flush stdio before fork() to avoid cloning buffers */
fflush(NULL);
async->pid = fork();
if (async->pid < 0) {
error("fork (async) failed: %s", strerror(errno));
goto error;
}
if (!async->pid) {
if (need_in)
close(fdin[1]);
if (need_out)
close(fdout[0]);
exit(!!async->proc(proc_in, proc_out, async->data));
}
if (need_in)
close(fdin[0]);
else if (async->in)
close(async->in);
if (need_out)
close(fdout[1]);
else if (async->out)
close(async->out);
#else
async->proc_in = proc_in;
async->proc_out = proc_out;
async->tid = (HANDLE) _beginthreadex(NULL, 0, run_thread, async, 0, NULL);
if (!async->tid) {
error("cannot create thread: %s", strerror(errno));
goto error;
}
#endif
return 0;
error:
if (need_in)
close_pair(fdin);
else if (async->in)
close(async->in);
if (need_out)
close_pair(fdout);
else if (async->out)
close(async->out);
return -1;
}
int finish_async(struct async *async)
{
#ifndef WIN32
int ret = wait_or_whine(async->pid, "child process", 0);
#else
DWORD ret = 0;
if (WaitForSingleObject(async->tid, INFINITE) != WAIT_OBJECT_0)
ret = error("waiting for thread failed: %lu", GetLastError());
else if (!GetExitCodeThread(async->tid, &ret))
ret = error("cannot get thread exit code: %lu", GetLastError());
CloseHandle(async->tid);
#endif
return ret;
}
int run_hook(const char *index_file, const char *name, ...)
{
struct child_process hook;
const char **argv = NULL, *env[2];
char index[PATH_MAX];
va_list args;
int ret;
size_t i = 0, alloc = 0;
if (access(git_path("hooks/%s", name), X_OK) < 0)
return 0;
va_start(args, name);
ALLOC_GROW(argv, i + 1, alloc);
argv[i++] = git_path("hooks/%s", name);
while (argv[i-1]) {
ALLOC_GROW(argv, i + 1, alloc);
argv[i++] = va_arg(args, const char *);
}
va_end(args);
memset(&hook, 0, sizeof(hook));
hook.argv = argv;
hook.no_stdin = 1;
hook.stdout_to_stderr = 1;
if (index_file) {
snprintf(index, sizeof(index), "GIT_INDEX_FILE=%s", index_file);
env[0] = index;
env[1] = NULL;
hook.env = env;
}
ret = run_command(&hook);
free(argv);
return ret;
}