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/**************************************************************************/
/* */
/* OCaml */
/* */
/* Xavier Leroy, projet Cambium, Collège de France and INRIA Paris */
/* */
/* Copyright 2020 Institut National de Recherche en Informatique et */
/* en Automatique. */
/* */
/* All rights reserved. This file is distributed under the terms of */
/* the GNU Lesser General Public License version 2.1, with the */
/* special exception on linking described in the file LICENSE. */
/* */
/**************************************************************************/
#define _GNU_SOURCE /* helps to find execvpe() */
#include <errno.h>
#include <sys/types.h>
#include <caml/mlvalues.h>
#include <caml/memory.h>
#include "caml/unixsupport.h"
extern char ** environ;
#ifdef HAS_POSIX_SPAWN
#include <spawn.h>
/* Implementation based on posix_spawn() */
CAMLprim value caml_unix_spawn(value executable, /* string */
value args, /* string array */
value optenv, /* string array option */
value usepath, /* bool */
value redirect) /* int array (size 3) */
{
char ** argv;
char ** envp;
const char * path;
pid_t pid;
int src, r;
posix_spawn_file_actions_t act;
caml_unix_check_path(executable, "create_process");
path = String_val(executable);
argv = caml_unix_cstringvect(args, "create_process");
if (Is_some(optenv)) {
envp = caml_unix_cstringvect(Some_val(optenv), "create_process");
} else {
envp = environ;
}
/* Prepare the redirections for stdin, stdout, stderr */
posix_spawn_file_actions_init(&act);
for (int dst = 0; dst <= 2; dst++) {
/* File descriptor [redirect.(dst)] becomes file descriptor [dst] */
src = Int_val(Field(redirect, dst));
if (src != dst) {
r = posix_spawn_file_actions_adddup2(&act, src, dst);
if (r != 0) goto error;
/* Close [src] if this is its last use */
for (int i = dst + 1; i <= 2; i++) {
if (src == Int_val(Field(redirect, i))) goto dontclose;
}
r = posix_spawn_file_actions_addclose(&act, src);
if (r != 0) goto error;
dontclose:
/*skip*/;
}
}
/* Spawn the new process */
if (Bool_val(usepath)) {
r = posix_spawnp(&pid, path, &act, NULL, argv, envp);
} else {
r = posix_spawn(&pid, path, &act, NULL, argv, envp);
}
error:
posix_spawn_file_actions_destroy(&act);
caml_unix_cstringvect_free(argv);
if (Is_some(optenv)) caml_unix_cstringvect_free(envp);
if (r != 0) caml_unix_error(r, "create_process", executable);
return Val_long(pid);
}
#else
/* Fallback implementation based on fork() and exec() */
/* Exit code used for the child process to report failure to exec */
/* This is consistent with system() and allowed by posix_spawn() specs */
#define ERROR_EXIT_STATUS 127
CAMLprim value caml_unix_spawn(value executable, /* string */
value args, /* string array */
value optenv, /* string array option */
value usepath, /* bool */
value redirect) /* int array (size 3) */
{
char ** argv;
char ** envp;
const char * path;
pid_t pid;
int src;
caml_unix_check_path(executable, "create_process");
path = String_val(executable);
argv = caml_unix_cstringvect(args, "create_process");
if (Is_some(optenv)) {
envp = caml_unix_cstringvect(Some_val(optenv), "create_process");
} else {
envp = NULL;
}
pid = fork();
if (pid != 0) {
/* This is the parent process */
caml_unix_cstringvect_free(argv);
if (envp != NULL) caml_unix_cstringvect_free(envp);
if (pid == -1) caml_uerror("create_process", executable);
return Val_long(pid);
}
/* This is the child process */
/* Perform the redirections for stdin, stdout, stderr */
for (int dst = 0; dst <= 2; dst++) {
/* File descriptor [redirect.(dst)] becomes file descriptor [dst] */
src = Int_val(Field(redirect, dst));
if (src != dst) {
if (dup2(src, dst) == -1) _exit(ERROR_EXIT_STATUS);
/* Close [src] if this is its last use */
for (int i = dst + 1; i <= 2; i++) {
if (src == Int_val(Field(redirect, i))) goto dontclose;
}
if (close(src) == -1) _exit(ERROR_EXIT_STATUS);
dontclose:
/*skip*/;
}
}
/* Transfer control to the executable */
if (Bool_val(usepath)) {
if (envp == NULL) {
execvp(path, argv);
} else {
#ifdef HAS_EXECVPE
execvpe(path, argv, envp);
#else
/* No other thread is running in the child process, so we can change
the global variable [environ] without bothering anyone. */
environ = envp;
execvp(path, argv);
#endif
}
} else {
if (envp == NULL) {
execv(path, argv);
} else {
execve(path, argv, envp);
}
}
/* If we get here, the exec*() call failed. */
_exit(ERROR_EXIT_STATUS);
}
#endif
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