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// SPDX-License-Identifier: GPL-2.0
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <string.h>
#include <linux/string.h>
#include <errno.h>
#include <sys/wait.h>
#include "subcmd-util.h"
#include "run-command.h"
#include "exec-cmd.h"
#define STRERR_BUFSIZE 128
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];
char sbuf[STRERR_BUFSIZE];
/*
* 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];
}
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, str_error_r(errno, sbuf, sizeof(sbuf)));
if (cmd->env) {
for (; *cmd->env; cmd->env++) {
if (strchr(*cmd->env, '='))
putenv((char*)*cmd->env);
else
unsetenv(*cmd->env);
}
}
if (cmd->preexec_cb)
cmd->preexec_cb();
if (cmd->no_exec_cmd)
exit(cmd->no_exec_cmd(cmd));
if (cmd->exec_cmd) {
execv_cmd(cmd->argv);
} else {
execvp(cmd->argv[0], (char *const*) cmd->argv);
}
exit(127);
}
if (cmd->pid < 0) {
int err = 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);
if (need_err)
close_pair(fderr);
return err == ENOENT ?
-ERR_RUN_COMMAND_EXEC :
-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(struct child_process *cmd, bool block)
{
bool finished = cmd->finished;
int result = cmd->finish_result;
while (!finished) {
int status, code;
pid_t waiting = waitpid(cmd->pid, &status, block ? 0 : WNOHANG);
if (!block && waiting == 0)
break;
if (waiting < 0 && errno == EINTR)
continue;
finished = true;
if (waiting < 0) {
char sbuf[STRERR_BUFSIZE];
fprintf(stderr, " Error: waitpid failed (%s)",
str_error_r(errno, sbuf, sizeof(sbuf)));
result = -ERR_RUN_COMMAND_WAITPID;
} else if (waiting != cmd->pid) {
result = -ERR_RUN_COMMAND_WAITPID_WRONG_PID;
} else if (WIFSIGNALED(status)) {
result = -ERR_RUN_COMMAND_WAITPID_SIGNAL;
} else if (!WIFEXITED(status)) {
result = -ERR_RUN_COMMAND_WAITPID_NOEXIT;
} else {
code = WEXITSTATUS(status);
switch (code) {
case 127:
result = -ERR_RUN_COMMAND_EXEC;
break;
case 0:
result = 0;
break;
default:
result = -code;
break;
}
}
}
if (finished) {
cmd->finished = 1;
cmd->finish_result = result;
}
return result;
}
int check_if_command_finished(struct child_process *cmd)
{
wait_or_whine(cmd, /*block=*/false);
return cmd->finished;
}
int finish_command(struct child_process *cmd)
{
return wait_or_whine(cmd, /*block=*/true);
}
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->exec_cmd = opt & RUN_EXEC_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);
}
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