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git/run-command.c
Jeff King 25043d8aea run-command: always set failed_errno in start_command 
When we fail to fork, we set the failed_errno variable to
the value of errno so it is not clobbered by later syscalls.
However, we do so in a conditional, and it is hard to see
later under what conditions the variable has a valid value.

Instead of setting it only when fork fails, let's just
always set it after forking. This is more obvious for human
readers (as we are no longer setting it as a side effect of
a strerror call), and it is more obvious to gcc, which no
longer generates a spurious -Wuninitialized warning. It also
happens to match what the WIN32 half of the #ifdef does.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2013-03-21 14:06:48 -07:00

787 lines
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#include "cache.h"
#include "run-command.h"
#include "exec_cmd.h"
#include "sigchain.h"
#include "argv-array.h"
#ifndef SHELL_PATH
# define SHELL_PATH "/bin/sh"
#endif
struct child_to_clean {
pid_t pid;
struct child_to_clean *next;
};
static struct child_to_clean *children_to_clean;
static int installed_child_cleanup_handler;
static void cleanup_children(int sig)
{
while (children_to_clean) {
struct child_to_clean *p = children_to_clean;
children_to_clean = p->next;
kill(p->pid, sig);
free(p);
}
}
static void cleanup_children_on_signal(int sig)
{
cleanup_children(sig);
sigchain_pop(sig);
raise(sig);
}
static void cleanup_children_on_exit(void)
{
cleanup_children(SIGTERM);
}
static void mark_child_for_cleanup(pid_t pid)
{
struct child_to_clean *p = xmalloc(sizeof(*p));
p->pid = pid;
p->next = children_to_clean;
children_to_clean = p;
if (!installed_child_cleanup_handler) {
atexit(cleanup_children_on_exit);
sigchain_push_common(cleanup_children_on_signal);
installed_child_cleanup_handler = 1;
}
}
static void clear_child_for_cleanup(pid_t pid)
{
struct child_to_clean **pp;
for (pp = &children_to_clean; *pp; pp = &(*pp)->next) {
struct child_to_clean *clean_me = *pp;
if (clean_me->pid == pid) {
*pp = clean_me->next;
free(clean_me);
return;
}
}
}
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 char *locate_in_PATH(const char *file)
{
const char *p = getenv("PATH");
struct strbuf buf = STRBUF_INIT;
if (!p || !*p)
return NULL;
while (1) {
const char *end = strchrnul(p, ':');
strbuf_reset(&buf);
/* POSIX specifies an empty entry as the current directory. */
if (end != p) {
strbuf_add(&buf, p, end - p);
strbuf_addch(&buf, '/');
}
strbuf_addstr(&buf, file);
if (!access(buf.buf, F_OK))
return strbuf_detach(&buf, NULL);
if (!*end)
break;
p = end + 1;
}
strbuf_release(&buf);
return NULL;
}
static int exists_in_PATH(const char *file)
{
char *r = locate_in_PATH(file);
free(r);
return r != NULL;
}
int sane_execvp(const char *file, char * const argv[])
{
if (!execvp(file, argv))
return 0; /* cannot happen ;-) */
/*
* When a command can't be found because one of the directories
* listed in $PATH is unsearchable, execvp reports EACCES, but
* careful usability testing (read: analysis of occasional bug
* reports) reveals that "No such file or directory" is more
* intuitive.
*
* We avoid commands with "/", because execvp will not do $PATH
* lookups in that case.
*
* The reassignment of EACCES to errno looks like a no-op below,
* but we need to protect against exists_in_PATH overwriting errno.
*/
if (errno == EACCES && !strchr(file, '/'))
errno = exists_in_PATH(file) ? EACCES : ENOENT;
else if (errno == ENOTDIR && !strchr(file, '/'))
errno = ENOENT;
return -1;
}
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])) {
#ifndef WIN32
nargv[nargc++] = SHELL_PATH;
#else
nargv[nargc++] = "sh";
#endif
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:");
sane_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)
{
/*
* execvp failed. If possible, we'd like to let start_command
* know, so failures like ENOENT can be handled right away; but
* otherwise, finish_command will still report the error.
*/
xwrite(child_notifier, "", 1);
}
static NORETURN void die_child(const char *err, va_list params)
{
vwritef(child_err, "fatal: ", err, params);
exit(128);
}
static void error_child(const char *err, va_list params)
{
vwritef(child_err, "error: ", err, params);
}
#endif
static inline void set_cloexec(int fd)
{
int flags = fcntl(fd, F_GETFD);
if (flags >= 0)
fcntl(fd, F_SETFD, flags | FD_CLOEXEC);
}
static int wait_or_whine(pid_t pid, const char *argv0)
{
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);
if (code != SIGINT && code != SIGQUIT)
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;
}
} else {
error("waitpid is confused (%s)", argv0);
}
clear_child_for_cleanup(pid);
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;
char *str;
/*
* 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);
str = "standard input";
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);
str = "standard output";
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);
str = "standard error";
fail_pipe:
error("cannot create %s pipe for %s: %s",
str, cmd->argv[0], strerror(failed_errno));
errno = failed_errno;
return -1;
}
cmd->err = fderr[0];
}
trace_argv_printf(cmd->argv, "trace: run_command:");
fflush(NULL);
#ifndef WIN32
{
int notify_pipe[2];
if (pipe(notify_pipe))
notify_pipe[0] = notify_pipe[1] = -1;
cmd->pid = fork();
failed_errno = errno;
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);
set_error_routine(error_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->git_cmd) {
execv_git_cmd(cmd->argv);
} else if (cmd->use_shell) {
execv_shell_cmd(cmd->argv);
} else {
sane_execvp(cmd->argv[0], (char *const*) cmd->argv);
}
if (errno == ENOENT) {
if (!cmd->silent_exec_failure)
error("cannot run %s: %s", cmd->argv[0],
strerror(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(errno));
else if (cmd->clean_on_exit)
mark_child_for_cleanup(cmd->pid);
/*
* 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]);
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->clean_on_exit && cmd->pid >= 0)
mark_child_for_cleanup(cmd->pid);
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]);
}
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;
cmd->clean_on_exit = opt & RUN_CLEAN_ON_EXIT ? 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);
}
#ifndef NO_PTHREADS
static pthread_t main_thread;
static int main_thread_set;
static pthread_key_t async_key;
static void *run_thread(void *data)
{
struct async *async = data;
intptr_t ret;
pthread_setspecific(async_key, async);
ret = async->proc(async->proc_in, async->proc_out, async->data);
return (void *)ret;
}
static NORETURN void die_async(const char *err, va_list params)
{
vreportf("fatal: ", err, params);
if (!pthread_equal(main_thread, pthread_self())) {
struct async *async = pthread_getspecific(async_key);
if (async->proc_in >= 0)
close(async->proc_in);
if (async->proc_out >= 0)
close(async->proc_out);
pthread_exit((void *)128);
}
exit(128);
}
#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;
#ifdef NO_PTHREADS
/* 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));
}
mark_child_for_cleanup(async->pid);
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
if (!main_thread_set) {
/*
* We assume that the first time that start_async is called
* it is from the main thread.
*/
main_thread_set = 1;
main_thread = pthread_self();
pthread_key_create(&async_key, NULL);
set_die_routine(die_async);
}
if (proc_in >= 0)
set_cloexec(proc_in);
if (proc_out >= 0)
set_cloexec(proc_out);
async->proc_in = proc_in;
async->proc_out = proc_out;
{
int err = pthread_create(&async->tid, NULL, run_thread, async);
if (err) {
error("cannot create thread: %s", strerror(err));
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)
{
#ifdef NO_PTHREADS
return wait_or_whine(async->pid, "child process");
#else
void *ret = (void *)(intptr_t)(-1);
if (pthread_join(async->tid, &ret))
error("pthread_join failed");
return (int)(intptr_t)ret;
#endif
}
char *find_hook(const char *name)
{
char *path = git_path("hooks/%s", name);
if (access(path, X_OK) < 0)
path = NULL;
return path;
}
int run_hook(const char *index_file, const char *name, ...)
{
struct child_process hook;
struct argv_array argv = ARGV_ARRAY_INIT;
const char *p, *env[2];
char index[PATH_MAX];
va_list args;
int ret;
p = find_hook(name);
if (!p)
return 0;
argv_array_push(&argv, p);
va_start(args, name);
while ((p = va_arg(args, const char *)))
argv_array_push(&argv, p);
va_end(args);
memset(&hook, 0, sizeof(hook));
hook.argv = 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);
argv_array_clear(&argv);
return ret;
}
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