git/run-command.c
Anders Melchiorsen 7d0b18a4da Add output flushing before fork()
This adds fflush(NULL) before fork() in start_command(), to keep
the generic interface safe.

A remaining use of fork() with no flushing is in a comment in
show_tree(). Rewrite that comment to use start_command().

Signed-off-by: Anders Melchiorsen <mail@cup.kalibalik.dk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2008-08-04 21:46:42 -07:00

351 lines
6.9 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]);
}
static inline void dup_devnull(int to)
{
int fd = open("/dev/null", O_RDWR);
dup2(fd, to);
close(fd);
}
int start_command(struct child_process *cmd)
{
int need_in, need_out, need_err;
int fdin[2], fdout[2], fderr[2];
/*
* In case of errors we must keep the promise to close FDs
* that have been passed in via ->in and ->out.
*/
need_in = !cmd->no_stdin && cmd->in < 0;
if (need_in) {
if (pipe(fdin) < 0) {
if (cmd->out > 0)
close(cmd->out);
return -ERR_RUN_COMMAND_PIPE;
}
cmd->in = fdin[1];
}
need_out = !cmd->no_stdout
&& !cmd->stdout_to_stderr
&& cmd->out < 0;
if (need_out) {
if (pipe(fdout) < 0) {
if (need_in)
close_pair(fdin);
else if (cmd->in)
close(cmd->in);
return -ERR_RUN_COMMAND_PIPE;
}
cmd->out = fdout[0];
}
need_err = !cmd->no_stderr && cmd->err < 0;
if (need_err) {
if (pipe(fderr) < 0) {
if (need_in)
close_pair(fdin);
else if (cmd->in)
close(cmd->in);
if (need_out)
close_pair(fdout);
else if (cmd->out)
close(cmd->out);
return -ERR_RUN_COMMAND_PIPE;
}
cmd->err = fderr[0];
}
trace_argv_printf(cmd->argv, "trace: run_command:");
#ifndef __MINGW32__
fflush(NULL);
cmd->pid = fork();
if (!cmd->pid) {
if (cmd->no_stdin)
dup_devnull(0);
else if (need_in) {
dup2(fdin[0], 0);
close_pair(fdin);
} else if (cmd->in) {
dup2(cmd->in, 0);
close(cmd->in);
}
if (cmd->no_stderr)
dup_devnull(2);
else if (need_err) {
dup2(fderr[1], 2);
close_pair(fderr);
}
if (cmd->no_stdout)
dup_devnull(1);
else if (cmd->stdout_to_stderr)
dup2(2, 1);
else if (need_out) {
dup2(fdout[1], 1);
close_pair(fdout);
} else if (cmd->out > 1) {
dup2(cmd->out, 1);
close(cmd->out);
}
if (cmd->dir && chdir(cmd->dir))
die("exec %s: cd to %s failed (%s)", cmd->argv[0],
cmd->dir, strerror(errno));
if (cmd->env) {
for (; *cmd->env; cmd->env++) {
if (strchr(*cmd->env, '='))
putenv((char*)*cmd->env);
else
unsetenv(*cmd->env);
}
}
if (cmd->git_cmd) {
execv_git_cmd(cmd->argv);
} else {
execvp(cmd->argv[0], (char *const*) cmd->argv);
}
die("exec %s failed.", cmd->argv[0]);
}
#else
int s0 = -1, s1 = -1, s2 = -1; /* backups of stdin, stdout, stderr */
const char **sargv = cmd->argv;
char **env = environ;
if (cmd->no_stdin) {
s0 = dup(0);
dup_devnull(0);
} else if (need_in) {
s0 = dup(0);
dup2(fdin[0], 0);
} else if (cmd->in) {
s0 = dup(0);
dup2(cmd->in, 0);
}
if (cmd->no_stderr) {
s2 = dup(2);
dup_devnull(2);
} else if (need_err) {
s2 = dup(2);
dup2(fderr[1], 2);
}
if (cmd->no_stdout) {
s1 = dup(1);
dup_devnull(1);
} else if (cmd->stdout_to_stderr) {
s1 = dup(1);
dup2(2, 1);
} else if (need_out) {
s1 = dup(1);
dup2(fdout[1], 1);
} else if (cmd->out > 1) {
s1 = dup(1);
dup2(cmd->out, 1);
}
if (cmd->dir)
die("chdir in start_command() not implemented");
if (cmd->env) {
env = copy_environ();
for (; *cmd->env; cmd->env++)
env = env_setenv(env, *cmd->env);
}
if (cmd->git_cmd) {
cmd->argv = prepare_git_cmd(cmd->argv);
}
cmd->pid = mingw_spawnvpe(cmd->argv[0], cmd->argv, env);
if (cmd->env)
free_environ(env);
if (cmd->git_cmd)
free(cmd->argv);
cmd->argv = sargv;
if (s0 >= 0)
dup2(s0, 0), close(s0);
if (s1 >= 0)
dup2(s1, 1), close(s1);
if (s2 >= 0)
dup2(s2, 2), close(s2);
#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);
return -ERR_RUN_COMMAND_FORK;
}
if (need_in)
close(fdin[0]);
else if (cmd->in)
close(cmd->in);
if (need_out)
close(fdout[1]);
else if (cmd->out)
close(cmd->out);
if (need_err)
close(fderr[1]);
return 0;
}
static int wait_or_whine(pid_t pid)
{
for (;;) {
int status, code;
pid_t waiting = waitpid(pid, &status, 0);
if (waiting < 0) {
if (errno == EINTR)
continue;
error("waitpid failed (%s)", strerror(errno));
return -ERR_RUN_COMMAND_WAITPID;
}
if (waiting != pid)
return -ERR_RUN_COMMAND_WAITPID_WRONG_PID;
if (WIFSIGNALED(status))
return -ERR_RUN_COMMAND_WAITPID_SIGNAL;
if (!WIFEXITED(status))
return -ERR_RUN_COMMAND_WAITPID_NOEXIT;
code = WEXITSTATUS(status);
if (code)
return -code;
return 0;
}
}
int finish_command(struct child_process *cmd)
{
return wait_or_whine(cmd->pid);
}
int run_command(struct child_process *cmd)
{
int code = start_command(cmd);
if (code)
return code;
return finish_command(cmd);
}
static void prepare_run_command_v_opt(struct child_process *cmd,
const char **argv,
int opt)
{
memset(cmd, 0, sizeof(*cmd));
cmd->argv = argv;
cmd->no_stdin = opt & RUN_COMMAND_NO_STDIN ? 1 : 0;
cmd->git_cmd = opt & RUN_GIT_CMD ? 1 : 0;
cmd->stdout_to_stderr = opt & RUN_COMMAND_STDOUT_TO_STDERR ? 1 : 0;
}
int run_command_v_opt(const char **argv, int opt)
{
struct child_process cmd;
prepare_run_command_v_opt(&cmd, argv, opt);
return run_command(&cmd);
}
int run_command_v_opt_cd(const char **argv, int opt, const char *dir)
{
struct child_process cmd;
prepare_run_command_v_opt(&cmd, argv, opt);
cmd.dir = dir;
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 __MINGW32__
static __stdcall unsigned run_thread(void *data)
{
struct async *async = data;
return async->proc(async->fd_for_proc, async->data);
}
#endif
int start_async(struct async *async)
{
int pipe_out[2];
if (pipe(pipe_out) < 0)
return error("cannot create pipe: %s", strerror(errno));
async->out = pipe_out[0];
#ifndef __MINGW32__
/* Flush stdio before fork() to avoid cloning buffers */
fflush(NULL);
async->pid = fork();
if (async->pid < 0) {
error("fork (async) failed: %s", strerror(errno));
close_pair(pipe_out);
return -1;
}
if (!async->pid) {
close(pipe_out[0]);
exit(!!async->proc(pipe_out[1], async->data));
}
close(pipe_out[1]);
#else
async->fd_for_proc = pipe_out[1];
async->tid = (HANDLE) _beginthreadex(NULL, 0, run_thread, async, 0, NULL);
if (!async->tid) {
error("cannot create thread: %s", strerror(errno));
close_pair(pipe_out);
return -1;
}
#endif
return 0;
}
int finish_async(struct async *async)
{
#ifndef __MINGW32__
int ret = 0;
if (wait_or_whine(async->pid))
ret = error("waitpid (async) failed");
#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;
}