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git/run-command.c
Jeff King 716c1f649e pipe_command(): mark stdin descriptor as non-blocking 
Our pipe_command() helper lets you both write to and read from a child
process on its stdin/stdout. It's supposed to work without deadlocks
because we use poll() to check when descriptors are ready for reading or
writing. But there's a bug: if both the data to be written and the data
to be read back exceed the pipe buffer, we'll deadlock.

The issue is that the code assumes that if you have, say, a 2MB buffer
to write and poll() tells you that the pipe descriptor is ready for
writing, that calling:

  write(cmd->in, buf, 2*1024*1024);

will do a partial write, filling the pipe buffer and then returning what
it did write. And that is what it would do on a socket, but not for a
pipe. When writing to a pipe, at least on Linux, it will block waiting
for the child process to read() more. And now we have a potential
deadlock, because the child may be writing back to us, waiting for us to
read() ourselves.

An easy way to trigger this is:

  git -c add.interactive.useBuiltin=true \
      -c interactive.diffFilter=cat \
      checkout -p HEAD~200

The diff against HEAD~200 will be big, and the filter wants to write all
of it back to us (obviously this is a dummy filter, but in the real
world something like diff-highlight would similarly stream back a big
output).

If you set add.interactive.useBuiltin to false, the problem goes away,
because now we're not using pipe_command() anymore (instead, that part
happens in perl). But this isn't a bug in the interactive code at all.
It's the underlying pipe_command() code which is broken, and has been
all along.

We presumably didn't notice because most calls only do input _or_
output, not both. And the few that do both, like gpg calls, may have
large inputs or outputs, but never both at the same time (e.g., consider
signing, which has a large payload but a small signature comes back).

The obvious fix is to put the descriptor into non-blocking mode, and
indeed, that makes the problem go away. Callers shouldn't need to
care, because they never see the descriptor (they hand us a buffer to
feed into it).

The included test fails reliably on Linux without this patch. Curiously,
it doesn't fail in our Windows CI environment, but has been reported to
do so for individual developers. It should pass in any environment after
this patch (courtesy of the compat/ layers added in the last few
commits).

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2022-08-17 09:21:41 -07:00

2015 lines
44 KiB
C
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#include "cache.h"
#include "run-command.h"
#include "exec-cmd.h"
#include "sigchain.h"
#include "strvec.h"
#include "thread-utils.h"
#include "strbuf.h"
#include "string-list.h"
#include "quote.h"
#include "config.h"
#include "packfile.h"
#include "hook.h"
#include "compat/nonblock.h"
void child_process_init(struct child_process *child)
{
struct child_process blank = CHILD_PROCESS_INIT;
memcpy(child, &blank, sizeof(*child));
}
void child_process_clear(struct child_process *child)
{
strvec_clear(&child->args);
strvec_clear(&child->env);
}
struct child_to_clean {
pid_t pid;
struct child_process *process;
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, int in_signal)
{
struct child_to_clean *children_to_wait_for = NULL;
while (children_to_clean) {
struct child_to_clean *p = children_to_clean;
children_to_clean = p->next;
if (p->process && !in_signal) {
struct child_process *process = p->process;
if (process->clean_on_exit_handler) {
trace_printf(
"trace: run_command: running exit handler for pid %"
PRIuMAX, (uintmax_t)p->pid
);
process->clean_on_exit_handler(process);
}
}
kill(p->pid, sig);
if (p->process && p->process->wait_after_clean) {
p->next = children_to_wait_for;
children_to_wait_for = p;
} else {
if (!in_signal)
free(p);
}
}
while (children_to_wait_for) {
struct child_to_clean *p = children_to_wait_for;
children_to_wait_for = p->next;
while (waitpid(p->pid, NULL, 0) < 0 && errno == EINTR)
; /* spin waiting for process exit or error */
if (!in_signal)
free(p);
}
}
static void cleanup_children_on_signal(int sig)
{
cleanup_children(sig, 1);
sigchain_pop(sig);
raise(sig);
}
static void cleanup_children_on_exit(void)
{
cleanup_children(SIGTERM, 0);
}
static void mark_child_for_cleanup(pid_t pid, struct child_process *process)
{
struct child_to_clean *p = xmalloc(sizeof(*p));
p->pid = pid;
p->process = process;
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]);
}
int is_executable(const char *name)
{
struct stat st;
if (stat(name, &st) || /* stat, not lstat */
!S_ISREG(st.st_mode))
return 0;
#if defined(GIT_WINDOWS_NATIVE)
/*
* On Windows there is no executable bit. The file extension
* indicates whether it can be run as an executable, and Git
* has special-handling to detect scripts and launch them
* through the indicated script interpreter. We test for the
* file extension first because virus scanners may make
* it quite expensive to open many files.
*/
if (ends_with(name, ".exe"))
return S_IXUSR;
{
/*
* Now that we know it does not have an executable extension,
* peek into the file instead.
*/
char buf[3] = { 0 };
int n;
int fd = open(name, O_RDONLY);
st.st_mode &= ~S_IXUSR;
if (fd >= 0) {
n = read(fd, buf, 2);
if (n == 2)
/* look for a she-bang */
if (!strcmp(buf, "#!"))
st.st_mode |= S_IXUSR;
close(fd);
}
}
#endif
return st.st_mode & S_IXUSR;
}
/*
* Search $PATH for a command. This emulates the path search that
* execvp would perform, without actually executing the command so it
* can be used before fork() to prepare to run a command using
* execve() or after execvp() to diagnose why it failed.
*
* The caller should ensure that file contains no directory
* separators.
*
* Returns the path to the command, as found in $PATH or NULL if the
* command could not be found. The caller inherits ownership of the memory
* used to store the resultant path.
*
* This should not be used on Windows, where the $PATH search rules
* are more complicated (e.g., a search for "foo" should find
* "foo.exe").
*/
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 (is_executable(buf.buf))
return strbuf_detach(&buf, NULL);
if (!*end)
break;
p = end + 1;
}
strbuf_release(&buf);
return NULL;
}
int exists_in_PATH(const char *command)
{
char *r = locate_in_PATH(command);
int found = r != NULL;
free(r);
return found;
}
int sane_execvp(const char *file, char * const argv[])
{
#ifndef GIT_WINDOWS_NATIVE
/*
* execvp() doesn't return, so we all we can do is tell trace2
* what we are about to do and let it leave a hint in the log
* (unless of course the execvp() fails).
*
* we skip this for Windows because the compat layer already
* has to emulate the execvp() call anyway.
*/
int exec_id = trace2_exec(file, (const char **)argv);
#endif
if (!execvp(file, argv))
return 0; /* cannot happen ;-) */
#ifndef GIT_WINDOWS_NATIVE
{
int ec = errno;
trace2_exec_result(exec_id, ec);
errno = ec;
}
#endif
/*
* 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 $PATH
* lookups in that case.
*
* The reassignment of EACCES to errno looks like a no-op below,
* but we need to protect against exists_in_PATH overwriting errno.
*/
if (errno == EACCES && !strchr(file, '/'))
errno = exists_in_PATH(file) ? EACCES : ENOENT;
else if (errno == ENOTDIR && !strchr(file, '/'))
errno = ENOENT;
return -1;
}
static const char **prepare_shell_cmd(struct strvec *out, const char **argv)
{
if (!argv[0])
BUG("shell command is empty");
if (strcspn(argv[0], "|&;<>()$`\\\"' \t\n*?[#~=%") != strlen(argv[0])) {
#ifndef GIT_WINDOWS_NATIVE
strvec_push(out, SHELL_PATH);
#else
strvec_push(out, "sh");
#endif
strvec_push(out, "-c");
/*
* If we have no extra arguments, we do not even need to
* bother with the "$@" magic.
*/
if (!argv[1])
strvec_push(out, argv[0]);
else
strvec_pushf(out, "%s \"$@\"", argv[0]);
}
strvec_pushv(out, argv);
return out->v;
}
#ifndef GIT_WINDOWS_NATIVE
static int child_notifier = -1;
enum child_errcode {
CHILD_ERR_CHDIR,
CHILD_ERR_DUP2,
CHILD_ERR_CLOSE,
CHILD_ERR_SIGPROCMASK,
CHILD_ERR_ENOENT,
CHILD_ERR_SILENT,
CHILD_ERR_ERRNO
};
struct child_err {
enum child_errcode err;
int syserr; /* errno */
};
static void child_die(enum child_errcode err)
{
struct child_err buf;
buf.err = err;
buf.syserr = errno;
/* write(2) on buf smaller than PIPE_BUF (min 512) is atomic: */
xwrite(child_notifier, &buf, sizeof(buf));
_exit(1);
}
static void child_dup2(int fd, int to)
{
if (dup2(fd, to) < 0)
child_die(CHILD_ERR_DUP2);
}
static void child_close(int fd)
{
if (close(fd))
child_die(CHILD_ERR_CLOSE);
}
static void child_close_pair(int fd[2])
{
child_close(fd[0]);
child_close(fd[1]);
}
static void child_error_fn(const char *err, va_list params)
{
const char msg[] = "error() should not be called in child\n";
xwrite(2, msg, sizeof(msg) - 1);
}
static void child_warn_fn(const char *err, va_list params)
{
const char msg[] = "warn() should not be called in child\n";
xwrite(2, msg, sizeof(msg) - 1);
}
static void NORETURN child_die_fn(const char *err, va_list params)
{
const char msg[] = "die() should not be called in child\n";
xwrite(2, msg, sizeof(msg) - 1);
_exit(2);
}
/* this runs in the parent process */
static void child_err_spew(struct child_process *cmd, struct child_err *cerr)
{
static void (*old_errfn)(const char *err, va_list params);
report_fn die_message_routine = get_die_message_routine();
old_errfn = get_error_routine();
set_error_routine(die_message_routine);
errno = cerr->syserr;
switch (cerr->err) {
case CHILD_ERR_CHDIR:
error_errno("exec '%s': cd to '%s' failed",
cmd->args.v[0], cmd->dir);
break;
case CHILD_ERR_DUP2:
error_errno("dup2() in child failed");
break;
case CHILD_ERR_CLOSE:
error_errno("close() in child failed");
break;
case CHILD_ERR_SIGPROCMASK:
error_errno("sigprocmask failed restoring signals");
break;
case CHILD_ERR_ENOENT:
error_errno("cannot run %s", cmd->args.v[0]);
break;
case CHILD_ERR_SILENT:
break;
case CHILD_ERR_ERRNO:
error_errno("cannot exec '%s'", cmd->args.v[0]);
break;
}
set_error_routine(old_errfn);
}
static int prepare_cmd(struct strvec *out, const struct child_process *cmd)
{
if (!cmd->args.v[0])
BUG("command is empty");
/*
* Add SHELL_PATH so in the event exec fails with ENOEXEC we can
* attempt to interpret the command with 'sh'.
*/
strvec_push(out, SHELL_PATH);
if (cmd->git_cmd) {
prepare_git_cmd(out, cmd->args.v);
} else if (cmd->use_shell) {
prepare_shell_cmd(out, cmd->args.v);
} else {
strvec_pushv(out, cmd->args.v);
}
/*
* If there are no dir separator characters in the command then perform
* a path lookup and use the resolved path as the command to exec. If
* there are dir separator characters, we have exec attempt to invoke
* the command directly.
*/
if (!has_dir_sep(out->v[1])) {
char *program = locate_in_PATH(out->v[1]);
if (program) {
free((char *)out->v[1]);
out->v[1] = program;
} else {
strvec_clear(out);
errno = ENOENT;
return -1;
}
}
return 0;
}
static char **prep_childenv(const char *const *deltaenv)
{
extern char **environ;
char **childenv;
struct string_list env = STRING_LIST_INIT_DUP;
struct strbuf key = STRBUF_INIT;
const char *const *p;
int i;
/* Construct a sorted string list consisting of the current environ */
for (p = (const char *const *) environ; p && *p; p++) {
const char *equals = strchr(*p, '=');
if (equals) {
strbuf_reset(&key);
strbuf_add(&key, *p, equals - *p);
string_list_append(&env, key.buf)->util = (void *) *p;
} else {
string_list_append(&env, *p)->util = (void *) *p;
}
}
string_list_sort(&env);
/* Merge in 'deltaenv' with the current environ */
for (p = deltaenv; p && *p; p++) {
const char *equals = strchr(*p, '=');
if (equals) {
/* ('key=value'), insert or replace entry */
strbuf_reset(&key);
strbuf_add(&key, *p, equals - *p);
string_list_insert(&env, key.buf)->util = (void *) *p;
} else {
/* otherwise ('key') remove existing entry */
string_list_remove(&env, *p, 0);
}
}
/* Create an array of 'char *' to be used as the childenv */
ALLOC_ARRAY(childenv, env.nr + 1);
for (i = 0; i < env.nr; i++)
childenv[i] = env.items[i].util;
childenv[env.nr] = NULL;
string_list_clear(&env, 0);
strbuf_release(&key);
return childenv;
}
struct atfork_state {
#ifndef NO_PTHREADS
int cs;
#endif
sigset_t old;
};
#define CHECK_BUG(err, msg) \
do { \
int e = (err); \
if (e) \
BUG("%s: %s", msg, strerror(e)); \
} while(0)
static void atfork_prepare(struct atfork_state *as)
{
sigset_t all;
if (sigfillset(&all))
die_errno("sigfillset");
#ifdef NO_PTHREADS
if (sigprocmask(SIG_SETMASK, &all, &as->old))
die_errno("sigprocmask");
#else
CHECK_BUG(pthread_sigmask(SIG_SETMASK, &all, &as->old),
"blocking all signals");
CHECK_BUG(pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &as->cs),
"disabling cancellation");
#endif
}
static void atfork_parent(struct atfork_state *as)
{
#ifdef NO_PTHREADS
if (sigprocmask(SIG_SETMASK, &as->old, NULL))
die_errno("sigprocmask");
#else
CHECK_BUG(pthread_setcancelstate(as->cs, NULL),
"re-enabling cancellation");
CHECK_BUG(pthread_sigmask(SIG_SETMASK, &as->old, NULL),
"restoring signal mask");
#endif
}
#endif /* GIT_WINDOWS_NATIVE */
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 in_signal)
{
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;
if (!in_signal)
error_errno("waitpid for %s failed", argv0);
} else if (waiting != pid) {
if (!in_signal)
error("waitpid is confused (%s)", argv0);
} else if (WIFSIGNALED(status)) {
code = WTERMSIG(status);
if (!in_signal && code != SIGINT && code != SIGQUIT && code != SIGPIPE)
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);
} else {
if (!in_signal)
error("waitpid is confused (%s)", argv0);
}
if (!in_signal)
clear_child_for_cleanup(pid);
errno = failed_errno;
return code;
}
static void trace_add_env(struct strbuf *dst, const char *const *deltaenv)
{
struct string_list envs = STRING_LIST_INIT_DUP;
const char *const *e;
int i;
int printed_unset = 0;
/* Last one wins, see run-command.c:prep_childenv() for context */
for (e = deltaenv; e && *e; e++) {
struct strbuf key = STRBUF_INIT;
char *equals = strchr(*e, '=');
if (equals) {
strbuf_add(&key, *e, equals - *e);
string_list_insert(&envs, key.buf)->util = equals + 1;
} else {
string_list_insert(&envs, *e)->util = NULL;
}
strbuf_release(&key);
}
/* "unset X Y...;" */
for (i = 0; i < envs.nr; i++) {
const char *var = envs.items[i].string;
const char *val = envs.items[i].util;
if (val || !getenv(var))
continue;
if (!printed_unset) {
strbuf_addstr(dst, " unset");
printed_unset = 1;
}
strbuf_addf(dst, " %s", var);
}
if (printed_unset)
strbuf_addch(dst, ';');
/* ... followed by "A=B C=D ..." */
for (i = 0; i < envs.nr; i++) {
const char *var = envs.items[i].string;
const char *val = envs.items[i].util;
const char *oldval;
if (!val)
continue;
oldval = getenv(var);
if (oldval && !strcmp(val, oldval))
continue;
strbuf_addf(dst, " %s=", var);
sq_quote_buf_pretty(dst, val);
}
string_list_clear(&envs, 0);
}
static void trace_run_command(const struct child_process *cp)
{
struct strbuf buf = STRBUF_INIT;
if (!trace_want(&trace_default_key))
return;
strbuf_addstr(&buf, "trace: run_command:");
if (cp->dir) {
strbuf_addstr(&buf, " cd ");
sq_quote_buf_pretty(&buf, cp->dir);
strbuf_addch(&buf, ';');
}
trace_add_env(&buf, cp->env.v);
if (cp->git_cmd)
strbuf_addstr(&buf, " git");
sq_quote_argv_pretty(&buf, cp->args.v);
trace_printf("%s", buf.buf);
strbuf_release(&buf);
}
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->args.v[0], strerror(failed_errno));
child_process_clear(cmd);
errno = failed_errno;
return -1;
}
cmd->err = fderr[0];
}
trace2_child_start(cmd);
trace_run_command(cmd);
fflush(NULL);
if (cmd->close_object_store)
close_object_store(the_repository->objects);
#ifndef GIT_WINDOWS_NATIVE
{
int notify_pipe[2];
int null_fd = -1;
char **childenv;
struct strvec argv = STRVEC_INIT;
struct child_err cerr;
struct atfork_state as;
if (prepare_cmd(&argv, cmd) < 0) {
failed_errno = errno;
cmd->pid = -1;
if (!cmd->silent_exec_failure)
error_errno("cannot run %s", cmd->args.v[0]);
goto end_of_spawn;
}
if (pipe(notify_pipe))
notify_pipe[0] = notify_pipe[1] = -1;
if (cmd->no_stdin || cmd->no_stdout || cmd->no_stderr) {
null_fd = xopen("/dev/null", O_RDWR | O_CLOEXEC);
set_cloexec(null_fd);
}
childenv = prep_childenv(cmd->env.v);
atfork_prepare(&as);
/*
* NOTE: In order to prevent deadlocking when using threads special
* care should be taken with the function calls made in between the
* fork() and exec() calls. No calls should be made to functions which
* require acquiring a lock (e.g. malloc) as the lock could have been
* held by another thread at the time of forking, causing the lock to
* never be released in the child process. This means only
* Async-Signal-Safe functions are permitted in the child.
*/
cmd->pid = fork();
failed_errno = errno;
if (!cmd->pid) {
int sig;
/*
* Ensure the default die/error/warn routines do not get
* called, they can take stdio locks and malloc.
*/
set_die_routine(child_die_fn);
set_error_routine(child_error_fn);
set_warn_routine(child_warn_fn);
close(notify_pipe[0]);
set_cloexec(notify_pipe[1]);
child_notifier = notify_pipe[1];
if (cmd->no_stdin)
child_dup2(null_fd, 0);
else if (need_in) {
child_dup2(fdin[0], 0);
child_close_pair(fdin);
} else if (cmd->in) {
child_dup2(cmd->in, 0);
child_close(cmd->in);
}
if (cmd->no_stderr)
child_dup2(null_fd, 2);
else if (need_err) {
child_dup2(fderr[1], 2);
child_close_pair(fderr);
} else if (cmd->err > 1) {
child_dup2(cmd->err, 2);
child_close(cmd->err);
}
if (cmd->no_stdout)
child_dup2(null_fd, 1);
else if (cmd->stdout_to_stderr)
child_dup2(2, 1);
else if (need_out) {
child_dup2(fdout[1], 1);
child_close_pair(fdout);
} else if (cmd->out > 1) {
child_dup2(cmd->out, 1);
child_close(cmd->out);
}
if (cmd->dir && chdir(cmd->dir))
child_die(CHILD_ERR_CHDIR);
/*
* restore default signal handlers here, in case
* we catch a signal right before execve below
*/
for (sig = 1; sig < NSIG; sig++) {
/* ignored signals get reset to SIG_DFL on execve */
if (signal(sig, SIG_DFL) == SIG_IGN)
signal(sig, SIG_IGN);
}
if (sigprocmask(SIG_SETMASK, &as.old, NULL) != 0)
child_die(CHILD_ERR_SIGPROCMASK);
/*
* Attempt to exec using the command and arguments starting at
* argv.argv[1]. argv.argv[0] contains SHELL_PATH which will
* be used in the event exec failed with ENOEXEC at which point
* we will try to interpret the command using 'sh'.
*/
execve(argv.v[1], (char *const *) argv.v + 1,
(char *const *) childenv);
if (errno == ENOEXEC)
execve(argv.v[0], (char *const *) argv.v,
(char *const *) childenv);
if (errno == ENOENT) {
if (cmd->silent_exec_failure)
child_die(CHILD_ERR_SILENT);
child_die(CHILD_ERR_ENOENT);
} else {
child_die(CHILD_ERR_ERRNO);
}
}
atfork_parent(&as);
if (cmd->pid < 0)
error_errno("cannot fork() for %s", cmd->args.v[0]);
else if (cmd->clean_on_exit)
mark_child_for_cleanup(cmd->pid, cmd);
/*
* Wait for child's exec. If the exec succeeds (or if fork()
* failed), EOF is seen immediately by the parent. Otherwise, the
* child process sends a child_err struct.
* Note that use of this infrastructure is completely advisory,
* therefore, we keep error checks minimal.
*/
close(notify_pipe[1]);
if (xread(notify_pipe[0], &cerr, sizeof(cerr)) == sizeof(cerr)) {
/*
* At this point we know that fork() succeeded, but exec()
* failed. Errors have been reported to our stderr.
*/
wait_or_whine(cmd->pid, cmd->args.v[0], 0);
child_err_spew(cmd, &cerr);
failed_errno = errno;
cmd->pid = -1;
}
close(notify_pipe[0]);
if (null_fd >= 0)
close(null_fd);
strvec_clear(&argv);
free(childenv);
}
end_of_spawn:
#else
{
int fhin = 0, fhout = 1, fherr = 2;
const char **sargv = cmd->args.v;
struct strvec nargv = STRVEC_INIT;
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->git_cmd)
cmd->args.v = prepare_git_cmd(&nargv, sargv);
else if (cmd->use_shell)
cmd->args.v = prepare_shell_cmd(&nargv, sargv);
cmd->pid = mingw_spawnvpe(cmd->args.v[0], cmd->args.v,
(char**) cmd->env.v,
cmd->dir, fhin, fhout, fherr);
failed_errno = errno;
if (cmd->pid < 0 && (!cmd->silent_exec_failure || errno != ENOENT))
error_errno("cannot spawn %s", cmd->args.v[0]);
if (cmd->clean_on_exit && cmd->pid >= 0)
mark_child_for_cleanup(cmd->pid, cmd);
strvec_clear(&nargv);
cmd->args.v = sargv;
if (fhin != 0)
close(fhin);
if (fhout != 1)
close(fhout);
if (fherr != 2)
close(fherr);
}
#endif
if (cmd->pid < 0) {
trace2_child_exit(cmd, -1);
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);
child_process_clear(cmd);
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)
{
int ret = wait_or_whine(cmd->pid, cmd->args.v[0], 0);
trace2_child_exit(cmd, ret);
child_process_clear(cmd);
invalidate_lstat_cache();
return ret;
}
int finish_command_in_signal(struct child_process *cmd)
{
int ret = wait_or_whine(cmd->pid, cmd->args.v[0], 1);
if (ret != -1)
trace2_child_exit(cmd, ret);
return ret;
}
int run_command(struct child_process *cmd)
{
int code;
if (cmd->out < 0 || cmd->err < 0)
BUG("run_command with a pipe can cause deadlock");
code = start_command(cmd);
if (code)
return code;
return finish_command(cmd);
}
int run_command_v_opt(const char **argv, int opt)
{
return run_command_v_opt_cd_env(argv, opt, NULL, NULL);
}
int run_command_v_opt_tr2(const char **argv, int opt, const char *tr2_class)
{
return run_command_v_opt_cd_env_tr2(argv, opt, NULL, NULL, tr2_class);
}
int run_command_v_opt_cd_env(const char **argv, int opt, const char *dir, const char *const *env)
{
return run_command_v_opt_cd_env_tr2(argv, opt, dir, env, NULL);
}
int run_command_v_opt_cd_env_tr2(const char **argv, int opt, const char *dir,
const char *const *env, const char *tr2_class)
{
struct child_process cmd = CHILD_PROCESS_INIT;
strvec_pushv(&cmd.args, 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;
cmd.wait_after_clean = opt & RUN_WAIT_AFTER_CLEAN ? 1 : 0;
cmd.close_object_store = opt & RUN_CLOSE_OBJECT_STORE ? 1 : 0;
cmd.dir = dir;
if (env)
strvec_pushv(&cmd.env, (const char **)env);
cmd.trace2_child_class = tr2_class;
return run_command(&cmd);
}
#ifndef NO_PTHREADS
static pthread_t main_thread;
static int main_thread_set;
static pthread_key_t async_key;
static pthread_key_t async_die_counter;
static void *run_thread(void *data)
{
struct async *async = data;
intptr_t ret;
if (async->isolate_sigpipe) {
sigset_t mask;
sigemptyset(&mask);
sigaddset(&mask, SIGPIPE);
if (pthread_sigmask(SIG_BLOCK, &mask, NULL) < 0) {
ret = error("unable to block SIGPIPE in async thread");
return (void *)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)
{
report_fn die_message_fn = get_die_message_routine();
die_message_fn(err, params);
if (in_async()) {
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);
}
static int async_die_is_recursing(void)
{
void *ret = pthread_getspecific(async_die_counter);
pthread_setspecific(async_die_counter, &async_die_counter); /* set to any non-NULL valid pointer */
return ret != NULL;
}
int in_async(void)
{
if (!main_thread_set)
return 0; /* no asyncs started yet */
return !pthread_equal(main_thread, pthread_self());
}
static void NORETURN async_exit(int code)
{
pthread_exit((void *)(intptr_t)code);
}
#else
static struct {
void (**handlers)(void);
size_t nr;
size_t alloc;
} git_atexit_hdlrs;
static int git_atexit_installed;
static void git_atexit_dispatch(void)
{
size_t i;
for (i=git_atexit_hdlrs.nr ; i ; i--)
git_atexit_hdlrs.handlers[i-1]();
}
static void git_atexit_clear(void)
{
free(git_atexit_hdlrs.handlers);
memset(&git_atexit_hdlrs, 0, sizeof(git_atexit_hdlrs));
git_atexit_installed = 0;
}
#undef atexit
int git_atexit(void (*handler)(void))
{
ALLOC_GROW(git_atexit_hdlrs.handlers, git_atexit_hdlrs.nr + 1, git_atexit_hdlrs.alloc);
git_atexit_hdlrs.handlers[git_atexit_hdlrs.nr++] = handler;
if (!git_atexit_installed) {
if (atexit(&git_atexit_dispatch))
return -1;
git_atexit_installed = 1;
}
return 0;
}
#define atexit git_atexit
static int process_is_async;
int in_async(void)
{
return process_is_async;
}
static void NORETURN async_exit(int code)
{
exit(code);
}
#endif
void check_pipe(int err)
{
if (err == EPIPE) {
if (in_async())
async_exit(141);
signal(SIGPIPE, SIG_DFL);
raise(SIGPIPE);
/* Should never happen, but just in case... */
exit(141);
}
}
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_errno("cannot create pipe");
}
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_errno("cannot create pipe");
}
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_errno("fork (async) failed");
goto error;
}
if (!async->pid) {
if (need_in)
close(fdin[1]);
if (need_out)
close(fdout[0]);
git_atexit_clear();
process_is_async = 1;
exit(!!async->proc(proc_in, proc_out, async->data));
}
mark_child_for_cleanup(async->pid, NULL);
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);
pthread_key_create(&async_die_counter, NULL);
set_die_routine(die_async);
set_die_is_recursing_routine(async_die_is_recursing);
}
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 async 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
int ret = wait_or_whine(async->pid, "child process", 0);
invalidate_lstat_cache();
return ret;
#else
void *ret = (void *)(intptr_t)(-1);
if (pthread_join(async->tid, &ret))
error("pthread_join failed");
invalidate_lstat_cache();
return (int)(intptr_t)ret;
#endif
}
int async_with_fork(void)
{
#ifdef NO_PTHREADS
return 1;
#else
return 0;
#endif
}
struct io_pump {
/* initialized by caller */
int fd;
int type; /* POLLOUT or POLLIN */
union {
struct {
const char *buf;
size_t len;
} out;
struct {
struct strbuf *buf;
size_t hint;
} in;
} u;
/* returned by pump_io */
int error; /* 0 for success, otherwise errno */
/* internal use */
struct pollfd *pfd;
};
static int pump_io_round(struct io_pump *slots, int nr, struct pollfd *pfd)
{
int pollsize = 0;
int i;
for (i = 0; i < nr; i++) {
struct io_pump *io = &slots[i];
if (io->fd < 0)
continue;
pfd[pollsize].fd = io->fd;
pfd[pollsize].events = io->type;
io->pfd = &pfd[pollsize++];
}
if (!pollsize)
return 0;
if (poll(pfd, pollsize, -1) < 0) {
if (errno == EINTR)
return 1;
die_errno("poll failed");
}
for (i = 0; i < nr; i++) {
struct io_pump *io = &slots[i];
if (io->fd < 0)
continue;
if (!(io->pfd->revents & (POLLOUT|POLLIN|POLLHUP|POLLERR|POLLNVAL)))
continue;
if (io->type == POLLOUT) {
ssize_t len;
/*
* Don't use xwrite() here. It loops forever on EAGAIN,
* and we're in our own poll() loop here.
*
* Note that we lose xwrite()'s handling of MAX_IO_SIZE
* and EINTR, so we have to implement those ourselves.
*/
len = write(io->fd, io->u.out.buf,
io->u.out.len <= MAX_IO_SIZE ?
io->u.out.len : MAX_IO_SIZE);
if (len < 0) {
if (errno != EINTR && errno != EAGAIN &&
errno != ENOSPC) {
io->error = errno;
close(io->fd);
io->fd = -1;
}
} else {
io->u.out.buf += len;
io->u.out.len -= len;
if (!io->u.out.len) {
close(io->fd);
io->fd = -1;
}
}
}
if (io->type == POLLIN) {
ssize_t len = strbuf_read_once(io->u.in.buf,
io->fd, io->u.in.hint);
if (len < 0)
io->error = errno;
if (len <= 0) {
close(io->fd);
io->fd = -1;
}
}
}
return 1;
}
static int pump_io(struct io_pump *slots, int nr)
{
struct pollfd *pfd;
int i;
for (i = 0; i < nr; i++)
slots[i].error = 0;
ALLOC_ARRAY(pfd, nr);
while (pump_io_round(slots, nr, pfd))
; /* nothing */
free(pfd);
/* There may be multiple errno values, so just pick the first. */
for (i = 0; i < nr; i++) {
if (slots[i].error) {
errno = slots[i].error;
return -1;
}
}
return 0;
}
int pipe_command(struct child_process *cmd,
const char *in, size_t in_len,
struct strbuf *out, size_t out_hint,
struct strbuf *err, size_t err_hint)
{
struct io_pump io[3];
int nr = 0;
if (in)
cmd->in = -1;
if (out)
cmd->out = -1;
if (err)
cmd->err = -1;
if (start_command(cmd) < 0)
return -1;
if (in) {
if (enable_pipe_nonblock(cmd->in) < 0) {
error_errno("unable to make pipe non-blocking");
close(cmd->in);
if (out)
close(cmd->out);
if (err)
close(cmd->err);
return -1;
}
io[nr].fd = cmd->in;
io[nr].type = POLLOUT;
io[nr].u.out.buf = in;
io[nr].u.out.len = in_len;
nr++;
}
if (out) {
io[nr].fd = cmd->out;
io[nr].type = POLLIN;
io[nr].u.in.buf = out;
io[nr].u.in.hint = out_hint;
nr++;
}
if (err) {
io[nr].fd = cmd->err;
io[nr].type = POLLIN;
io[nr].u.in.buf = err;
io[nr].u.in.hint = err_hint;
nr++;
}
if (pump_io(io, nr) < 0) {
finish_command(cmd); /* throw away exit code */
return -1;
}
return finish_command(cmd);
}
enum child_state {
GIT_CP_FREE,
GIT_CP_WORKING,
GIT_CP_WAIT_CLEANUP,
};
int run_processes_parallel_ungroup;
struct parallel_processes {
void *data;
int max_processes;
int nr_processes;
get_next_task_fn get_next_task;
start_failure_fn start_failure;
task_finished_fn task_finished;
struct {
enum child_state state;
struct child_process process;
struct strbuf err;
void *data;
} *children;
/*
* The struct pollfd is logically part of *children,
* but the system call expects it as its own array.
*/
struct pollfd *pfd;
unsigned shutdown : 1;
unsigned ungroup : 1;
int output_owner;
struct strbuf buffered_output; /* of finished children */
};
static int default_start_failure(struct strbuf *out,
void *pp_cb,
void *pp_task_cb)
{
return 0;
}
static int default_task_finished(int result,
struct strbuf *out,
void *pp_cb,
void *pp_task_cb)
{
return 0;
}
static void kill_children(struct parallel_processes *pp, int signo)
{
int i, n = pp->max_processes;
for (i = 0; i < n; i++)
if (pp->children[i].state == GIT_CP_WORKING)
kill(pp->children[i].process.pid, signo);
}
static struct parallel_processes *pp_for_signal;
static void handle_children_on_signal(int signo)
{
kill_children(pp_for_signal, signo);
sigchain_pop(signo);
raise(signo);
}
static void pp_init(struct parallel_processes *pp,
int n,
get_next_task_fn get_next_task,
start_failure_fn start_failure,
task_finished_fn task_finished,
void *data, int ungroup)
{
int i;
if (n < 1)
n = online_cpus();
pp->max_processes = n;
trace_printf("run_processes_parallel: preparing to run up to %d tasks", n);
pp->data = data;
if (!get_next_task)
BUG("you need to specify a get_next_task function");
pp->get_next_task = get_next_task;
pp->start_failure = start_failure ? start_failure : default_start_failure;
pp->task_finished = task_finished ? task_finished : default_task_finished;
pp->nr_processes = 0;
pp->output_owner = 0;
pp->shutdown = 0;
pp->ungroup = ungroup;
CALLOC_ARRAY(pp->children, n);
if (pp->ungroup)
pp->pfd = NULL;
else
CALLOC_ARRAY(pp->pfd, n);
strbuf_init(&pp->buffered_output, 0);
for (i = 0; i < n; i++) {
strbuf_init(&pp->children[i].err, 0);
child_process_init(&pp->children[i].process);
if (pp->pfd) {
pp->pfd[i].events = POLLIN | POLLHUP;
pp->pfd[i].fd = -1;
}
}
pp_for_signal = pp;
sigchain_push_common(handle_children_on_signal);
}
static void pp_cleanup(struct parallel_processes *pp)
{
int i;
trace_printf("run_processes_parallel: done");
for (i = 0; i < pp->max_processes; i++) {
strbuf_release(&pp->children[i].err);
child_process_clear(&pp->children[i].process);
}
free(pp->children);
free(pp->pfd);
/*
* When get_next_task added messages to the buffer in its last
* iteration, the buffered output is non empty.
*/
strbuf_write(&pp->buffered_output, stderr);
strbuf_release(&pp->buffered_output);
sigchain_pop_common();
}
/* returns
* 0 if a new task was started.
* 1 if no new jobs was started (get_next_task ran out of work, non critical
* problem with starting a new command)
* <0 no new job was started, user wishes to shutdown early. Use negative code
* to signal the children.
*/
static int pp_start_one(struct parallel_processes *pp)
{
int i, code;
for (i = 0; i < pp->max_processes; i++)
if (pp->children[i].state == GIT_CP_FREE)
break;
if (i == pp->max_processes)
BUG("bookkeeping is hard");
code = pp->get_next_task(&pp->children[i].process,
pp->ungroup ? NULL : &pp->children[i].err,
pp->data,
&pp->children[i].data);
if (!code) {
if (!pp->ungroup) {
strbuf_addbuf(&pp->buffered_output, &pp->children[i].err);
strbuf_reset(&pp->children[i].err);
}
return 1;
}
if (!pp->ungroup) {
pp->children[i].process.err = -1;
pp->children[i].process.stdout_to_stderr = 1;
}
pp->children[i].process.no_stdin = 1;
if (start_command(&pp->children[i].process)) {
code = pp->start_failure(pp->ungroup ? NULL :
&pp->children[i].err,
pp->data,
pp->children[i].data);
if (!pp->ungroup) {
strbuf_addbuf(&pp->buffered_output, &pp->children[i].err);
strbuf_reset(&pp->children[i].err);
}
if (code)
pp->shutdown = 1;
return code;
}
pp->nr_processes++;
pp->children[i].state = GIT_CP_WORKING;
if (pp->pfd)
pp->pfd[i].fd = pp->children[i].process.err;
return 0;
}
static void pp_buffer_stderr(struct parallel_processes *pp, int output_timeout)
{
int i;
while ((i = poll(pp->pfd, pp->max_processes, output_timeout)) < 0) {
if (errno == EINTR)
continue;
pp_cleanup(pp);
die_errno("poll");
}
/* Buffer output from all pipes. */
for (i = 0; i < pp->max_processes; i++) {
if (pp->children[i].state == GIT_CP_WORKING &&
pp->pfd[i].revents & (POLLIN | POLLHUP)) {
int n = strbuf_read_once(&pp->children[i].err,
pp->children[i].process.err, 0);
if (n == 0) {
close(pp->children[i].process.err);
pp->children[i].state = GIT_CP_WAIT_CLEANUP;
} else if (n < 0)
if (errno != EAGAIN)
die_errno("read");
}
}
}
static void pp_output(struct parallel_processes *pp)
{
int i = pp->output_owner;
if (pp->children[i].state == GIT_CP_WORKING &&
pp->children[i].err.len) {
strbuf_write(&pp->children[i].err, stderr);
strbuf_reset(&pp->children[i].err);
}
}
static int pp_collect_finished(struct parallel_processes *pp)
{
int i, code;
int n = pp->max_processes;
int result = 0;
while (pp->nr_processes > 0) {
for (i = 0; i < pp->max_processes; i++)
if (pp->children[i].state == GIT_CP_WAIT_CLEANUP)
break;
if (i == pp->max_processes)
break;
code = finish_command(&pp->children[i].process);
code = pp->task_finished(code, pp->ungroup ? NULL :
&pp->children[i].err, pp->data,
pp->children[i].data);
if (code)
result = code;
if (code < 0)
break;
pp->nr_processes--;
pp->children[i].state = GIT_CP_FREE;
if (pp->pfd)
pp->pfd[i].fd = -1;
child_process_init(&pp->children[i].process);
if (pp->ungroup) {
; /* no strbuf_*() work to do here */
} else if (i != pp->output_owner) {
strbuf_addbuf(&pp->buffered_output, &pp->children[i].err);
strbuf_reset(&pp->children[i].err);
} else {
strbuf_write(&pp->children[i].err, stderr);
strbuf_reset(&pp->children[i].err);
/* Output all other finished child processes */
strbuf_write(&pp->buffered_output, stderr);
strbuf_reset(&pp->buffered_output);
/*
* Pick next process to output live.
* NEEDSWORK:
* For now we pick it randomly by doing a round
* robin. Later we may want to pick the one with
* the most output or the longest or shortest
* running process time.
*/
for (i = 0; i < n; i++)
if (pp->children[(pp->output_owner + i) % n].state == GIT_CP_WORKING)
break;
pp->output_owner = (pp->output_owner + i) % n;
}
}
return result;
}
int run_processes_parallel(int n,
get_next_task_fn get_next_task,
start_failure_fn start_failure,
task_finished_fn task_finished,
void *pp_cb)
{
int i, code;
int output_timeout = 100;
int spawn_cap = 4;
int ungroup = run_processes_parallel_ungroup;
struct parallel_processes pp;
/* unset for the next API user */
run_processes_parallel_ungroup = 0;
pp_init(&pp, n, get_next_task, start_failure, task_finished, pp_cb,
ungroup);
while (1) {
for (i = 0;
i < spawn_cap && !pp.shutdown &&
pp.nr_processes < pp.max_processes;
i++) {
code = pp_start_one(&pp);
if (!code)
continue;
if (code < 0) {
pp.shutdown = 1;
kill_children(&pp, -code);
}
break;
}
if (!pp.nr_processes)
break;
if (ungroup) {
int i;
for (i = 0; i < pp.max_processes; i++)
pp.children[i].state = GIT_CP_WAIT_CLEANUP;
} else {
pp_buffer_stderr(&pp, output_timeout);
pp_output(&pp);
}
code = pp_collect_finished(&pp);
if (code) {
pp.shutdown = 1;
if (code < 0)
kill_children(&pp, -code);
}
}
pp_cleanup(&pp);
return 0;
}
int run_processes_parallel_tr2(int n, get_next_task_fn get_next_task,
start_failure_fn start_failure,
task_finished_fn task_finished, void *pp_cb,
const char *tr2_category, const char *tr2_label)
{
int result;
trace2_region_enter_printf(tr2_category, tr2_label, NULL, "max:%d",
((n < 1) ? online_cpus() : n));
result = run_processes_parallel(n, get_next_task, start_failure,
task_finished, pp_cb);
trace2_region_leave(tr2_category, tr2_label, NULL);
return result;
}
int run_auto_maintenance(int quiet)
{
int enabled;
struct child_process maint = CHILD_PROCESS_INIT;
if (!git_config_get_bool("maintenance.auto", &enabled) &&
!enabled)
return 0;
maint.git_cmd = 1;
maint.close_object_store = 1;
strvec_pushl(&maint.args, "maintenance", "run", "--auto", NULL);
strvec_push(&maint.args, quiet ? "--quiet" : "--no-quiet");
return run_command(&maint);
}
void prepare_other_repo_env(struct strvec *env, const char *new_git_dir)
{
const char * const *var;
for (var = local_repo_env; *var; var++) {
if (strcmp(*var, CONFIG_DATA_ENVIRONMENT) &&
strcmp(*var, CONFIG_COUNT_ENVIRONMENT))
strvec_push(env, *var);
}
strvec_pushf(env, "%s=%s", GIT_DIR_ENVIRONMENT, new_git_dir);
}
enum start_bg_result start_bg_command(struct child_process *cmd,
start_bg_wait_cb *wait_cb,
void *cb_data,
unsigned int timeout_sec)
{
enum start_bg_result sbgr = SBGR_ERROR;
int ret;
int wait_status;
pid_t pid_seen;
time_t time_limit;
/*
* We do not allow clean-on-exit because the child process
* should persist in the background and possibly/probably
* after this process exits. So we don't want to kill the
* child during our atexit routine.
*/
if (cmd->clean_on_exit)
BUG("start_bg_command() does not allow non-zero clean_on_exit");
if (!cmd->trace2_child_class)
cmd->trace2_child_class = "background";
ret = start_command(cmd);
if (ret) {
/*
* We assume that if `start_command()` fails, we
* either get a complete `trace2_child_start() /
* trace2_child_exit()` pair or it fails before the
* `trace2_child_start()` is emitted, so we do not
* need to worry about it here.
*
* We also assume that `start_command()` does not add
* us to the cleanup list. And that it calls
* calls `child_process_clear()`.
*/
sbgr = SBGR_ERROR;
goto done;
}
time(&time_limit);
time_limit += timeout_sec;
wait:
pid_seen = waitpid(cmd->pid, &wait_status, WNOHANG);
if (!pid_seen) {
/*
* The child is currently running. Ask the callback
* if the child is ready to do work or whether we
* should keep waiting for it to boot up.
*/
ret = (*wait_cb)(cmd, cb_data);
if (!ret) {
/*
* The child is running and "ready".
*/
trace2_child_ready(cmd, "ready");
sbgr = SBGR_READY;
goto done;
} else if (ret > 0) {
/*
* The callback said to give it more time to boot up
* (subject to our timeout limit).
*/
time_t now;
time(&now);
if (now < time_limit)
goto wait;
/*
* Our timeout has expired. We don't try to
* kill the child, but rather let it continue
* (hopefully) trying to startup.
*/
trace2_child_ready(cmd, "timeout");
sbgr = SBGR_TIMEOUT;
goto done;
} else {
/*
* The cb gave up on this child. It is still running,
* but our cb got an error trying to probe it.
*/
trace2_child_ready(cmd, "error");
sbgr = SBGR_CB_ERROR;
goto done;
}
}
else if (pid_seen == cmd->pid) {
int child_code = -1;
/*
* The child started, but exited or was terminated
* before becoming "ready".
*
* We try to match the behavior of `wait_or_whine()`
* WRT the handling of WIFSIGNALED() and WIFEXITED()
* and convert the child's status to a return code for
* tracing purposes and emit the `trace2_child_exit()`
* event.
*
* We do not want the wait_or_whine() error message
* because we will be called by client-side library
* routines.
*/
if (WIFEXITED(wait_status))
child_code = WEXITSTATUS(wait_status);
else if (WIFSIGNALED(wait_status))
child_code = WTERMSIG(wait_status) + 128;
trace2_child_exit(cmd, child_code);
sbgr = SBGR_DIED;
goto done;
}
else if (pid_seen < 0 && errno == EINTR)
goto wait;
trace2_child_exit(cmd, -1);
sbgr = SBGR_ERROR;
done:
child_process_clear(cmd);
invalidate_lstat_cache();
return sbgr;
}
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