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#include <pthread.h>
#include "argv-array.h"
struct child_process {
const char **argv;
struct argv_array args;
struct argv_array env_array;
pid_t pid;
* Using .in, .out, .err:
* - Specify 0 for no redirections (child inherits stdin, stdout,
* stderr from parent).
* - Specify -1 to have a pipe allocated as follows:
* .in: returns the writable pipe end; parent writes to it,
* the readable pipe end becomes child's stdin
* .out, .err: returns the readable pipe end; parent reads from
* it, the writable pipe end becomes child's stdout/stderr
* The caller of start_command() must close the returned FDs
* after it has completed reading from/writing to it!
* - Specify > 0 to set a channel to a particular FD as follows:
* .in: a readable FD, becomes child's stdin
* .out: a writable FD, becomes child's stdout/stderr
* .err: a writable FD, becomes child's stderr
* The specified FD is closed by start_command(), even in case
* of errors!
int in;
int out;
int err;
const char *dir;
const char *const *env;
unsigned no_stdin:1;
unsigned no_stdout:1;
unsigned no_stderr:1;
unsigned git_cmd:1; /* if this is to be git sub-command */
unsigned silent_exec_failure:1;
unsigned stdout_to_stderr:1;
unsigned use_shell:1;
unsigned clean_on_exit:1;
void child_process_init(struct child_process *);
void child_process_clear(struct child_process *);
int start_command(struct child_process *);
int finish_command(struct child_process *);
pager: don't use unsafe functions in signal handlers Since the commit a3da8821208d (pager: do wait_for_pager on signal death), we call wait_for_pager() in the pager's signal handler. The recent bug report revealed that this causes a deadlock in glibc at aborting "git log" [*1*]. When this happens, git process is left unterminated, and it can't be killed by SIGTERM but only by SIGKILL. The problem is that wait_for_pager() function does more than waiting for pager process's termination, but it does cleanups and printing errors. Unfortunately, the functions that may be used in a signal handler are very limited [*2*]. Particularly, malloc(), free() and the variants can't be used in a signal handler because they take a mutex internally in glibc. This was the cause of the deadlock above. Other than the direct calls of malloc/free, many functions calling malloc/free can't be used. strerror() is such one, either. Also the usage of fflush() and printf() in a signal handler is bad, although it seems working so far. In a safer side, we should avoid them, too. This patch tries to reduce the calls of such functions in signal handlers. wait_for_signal() takes a flag and avoids the unsafe calls. Also, finish_command_in_signal() is introduced for the same reason. There the free() calls are removed, and only waits for the children without whining at errors. [*1*] [*2*] Signed-off-by: Takashi Iwai <> Reviewed-by: Jeff King <> Signed-off-by: Junio C Hamano <>
7 years ago
int finish_command_in_signal(struct child_process *);
int run_command(struct child_process *);
* Returns the path to the hook file, or NULL if the hook is missing
* or disabled. Note that this points to static storage that will be
* overwritten by further calls to find_hook and run_hook_*.
extern const char *find_hook(const char *name);
extern int run_hook_le(const char *const *env, const char *name, ...);
extern int run_hook_ve(const char *const *env, const char *name, va_list args);
#define RUN_GIT_CMD 2 /*If this is to be git sub-command */
#define RUN_USING_SHELL 16
#define RUN_CLEAN_ON_EXIT 32
int run_command_v_opt(const char **argv, int opt);
* env (the environment) is to be formatted like environ: "VAR=VALUE".
* To unset an environment variable use just "VAR".
int run_command_v_opt_cd_env(const char **argv, int opt, const char *dir, const char *const *env);
* Execute the given command, capturing its stdout in the given strbuf.
* Returns -1 if starting the command fails or reading fails, and otherwise
* returns the exit code of the command. The output collected in the
* buffer is kept even if the command returns a non-zero exit. The hint field
* gives a starting size for the strbuf allocation.
* The fields of "cmd" should be set up as they would for a normal run_command
* invocation. But note that there is no need to set cmd->out; the function
* sets it up for the caller.
int capture_command(struct child_process *cmd, struct strbuf *buf, size_t hint);
* The purpose of the following functions is to feed a pipe by running
* a function asynchronously and providing output that the caller reads.
* It is expected that no synchronization and mutual exclusion between
* the caller and the feed function is necessary so that the function
* can run in a thread without interfering with the caller.
struct async {
* proc reads from in; closes it before return
* proc writes to out; closes it before return
* returns 0 on success, non-zero on failure
int (*proc)(int in, int out, void *data);
void *data;
int in; /* caller writes here and closes it */
int out; /* caller reads from here and closes it */
pid_t pid;
pthread_t tid;
int proc_in;
int proc_out;
int start_async(struct async *async);
int finish_async(struct async *async);
int in_async(void);