(os/spawn args &opt flags env)
Execute a program on the system and return a handle to the process.
Otherwise, takes the same arguments as os/execute.
Does not wait for the process.
For each of the :in, :out, and :err keys of the env argument, one
can also pass in the keyword :pipe to get streams for standard IO of
the subprocess that can be read from and written to.
the following description doesn't seem quite accurate. see this code for specifics
The returned value proc has the fields :in, :out, :err, and the
additional field :pid on unix-like platforms. Use (os/proc-wait proc) to rejoin the subprocess. After waiting completes, proc gains a
new field, :return-code.
below seems true (even for Windows), initially thought it would be better to put the info at the website, but now am not so sure
If :x flag is used, a non-zero exit code will cause calls to certain
functions such as os/proc-wait, os/proc-close, and os/proc-kill
(things that lead to a call of os_proc_wait_impl [1] basically can
trigger this
code)
to raise an error.
[1] os/execute (but not os/spawn) can also call
os_proc_wait_impl.
(def p (os/spawn ["ls" "1"] :px))
(try
(os/proc-wait p)
([e]
(eprint "error from os/proc-wait")
(eprint e)))(def p (os/spawn ["ls" "1"] :px))
(try
(os/proc-close p)
([e]
(eprint "error from os/proc-close")
(eprint e)))static Janet os_execute_impl(int32_t argc, Janet *argv, JanetExecuteMode mode) {
janet_sandbox_assert(JANET_SANDBOX_SUBPROCESS);
janet_arity(argc, 1, 3);
/* Get flags */
int is_spawn = mode == JANET_EXECUTE_SPAWN;
uint64_t flags = 0;
if (argc > 1) {
flags = janet_getflags(argv, 1, "epxd");
}
/* Get environment */
int use_environ = !janet_flag_at(flags, 0);
EnvBlock envp = os_execute_env(argc, argv);
/* Get arguments */
JanetView exargs = janet_getindexed(argv, 0);
if (exargs.len < 1) {
janet_panic("expected at least 1 command line argument");
}
/* Optional stdio redirections */
JanetAbstract orig_in = NULL, orig_out = NULL, orig_err = NULL;
JanetHandle new_in = JANET_HANDLE_NONE, new_out = JANET_HANDLE_NONE, new_err = JANET_HANDLE_NONE;
JanetHandle pipe_in = JANET_HANDLE_NONE, pipe_out = JANET_HANDLE_NONE, pipe_err = JANET_HANDLE_NONE;
int pipe_errflag = 0; /* Track errors setting up pipes */
int pipe_owner_flags = (is_spawn && (flags & 0x8)) ? JANET_PROC_ALLOW_ZOMBIE : 0;
/* Get optional redirections */
if (argc > 2 && (mode != JANET_EXECUTE_EXEC)) {
JanetDictView tab = janet_getdictionary(argv, 2);
Janet maybe_stdin = janet_dictionary_get(tab.kvs, tab.cap, janet_ckeywordv("in"));
Janet maybe_stdout = janet_dictionary_get(tab.kvs, tab.cap, janet_ckeywordv("out"));
Janet maybe_stderr = janet_dictionary_get(tab.kvs, tab.cap, janet_ckeywordv("err"));
if (is_spawn && janet_keyeq(maybe_stdin, "pipe")) {
new_in = make_pipes(&pipe_in, 1, &pipe_errflag);
pipe_owner_flags |= JANET_PROC_OWNS_STDIN;
} else if (!janet_checktype(maybe_stdin, JANET_NIL)) {
new_in = janet_getjstream(&maybe_stdin, 0, &orig_in);
}
if (is_spawn && janet_keyeq(maybe_stdout, "pipe")) {
new_out = make_pipes(&pipe_out, 0, &pipe_errflag);
pipe_owner_flags |= JANET_PROC_OWNS_STDOUT;
} else if (!janet_checktype(maybe_stdout, JANET_NIL)) {
new_out = janet_getjstream(&maybe_stdout, 0, &orig_out);
}
if (is_spawn && janet_keyeq(maybe_stderr, "pipe")) {
new_err = make_pipes(&pipe_err, 0, &pipe_errflag);
pipe_owner_flags |= JANET_PROC_OWNS_STDERR;
} else if (!janet_checktype(maybe_stderr, JANET_NIL)) {
new_err = janet_getjstream(&maybe_stderr, 0, &orig_err);
}
}
/* Clean up if any of the pipes have any issues */
if (pipe_errflag) {
if (pipe_in != JANET_HANDLE_NONE) close_handle(pipe_in);
if (pipe_out != JANET_HANDLE_NONE) close_handle(pipe_out);
if (pipe_err != JANET_HANDLE_NONE) close_handle(pipe_err);
janet_panic("failed to create pipes");
}
#ifdef JANET_WINDOWS
HANDLE pHandle, tHandle;
SECURITY_ATTRIBUTES saAttr;
PROCESS_INFORMATION processInfo;
STARTUPINFO startupInfo;
memset(&saAttr, 0, sizeof(saAttr));
memset(&processInfo, 0, sizeof(processInfo));
memset(&startupInfo, 0, sizeof(startupInfo));
startupInfo.cb = sizeof(startupInfo);
startupInfo.dwFlags |= STARTF_USESTDHANDLES;
saAttr.nLength = sizeof(saAttr);
JanetBuffer *buf = os_exec_escape(exargs);
if (buf->count > 8191) {
if (pipe_in != JANET_HANDLE_NONE) CloseHandle(pipe_in);
if (pipe_out != JANET_HANDLE_NONE) CloseHandle(pipe_out);
if (pipe_err != JANET_HANDLE_NONE) CloseHandle(pipe_err);
janet_panic("command line string too long (max 8191 characters)");
}
const char *path = (const char *) janet_unwrap_string(exargs.items[0]);
/* Do IO redirection */
if (pipe_in != JANET_HANDLE_NONE) {
startupInfo.hStdInput = pipe_in;
} else if (new_in != JANET_HANDLE_NONE) {
startupInfo.hStdInput = new_in;
} else {
startupInfo.hStdInput = (HANDLE) _get_osfhandle(0);
}
if (pipe_out != JANET_HANDLE_NONE) {
startupInfo.hStdOutput = pipe_out;
} else if (new_out != JANET_HANDLE_NONE) {
startupInfo.hStdOutput = new_out;
} else {
startupInfo.hStdOutput = (HANDLE) _get_osfhandle(1);
}
if (pipe_err != JANET_HANDLE_NONE) {
startupInfo.hStdError = pipe_err;
} else if (new_err != NULL) {
startupInfo.hStdError = new_err;
} else {
startupInfo.hStdError = (HANDLE) _get_osfhandle(2);
}
int cp_failed = 0;
if (!CreateProcess(janet_flag_at(flags, 1) ? NULL : path,
(char *) buf->data, /* Single CLI argument */
&saAttr, /* no proc inheritance */
&saAttr, /* no thread inheritance */
TRUE, /* handle inheritance */
0, /* flags */
use_environ ? NULL : envp, /* pass in environment */
NULL, /* use parents starting directory */
&startupInfo,
&processInfo)) {
cp_failed = 1;
}
if (pipe_in != JANET_HANDLE_NONE) CloseHandle(pipe_in);
if (pipe_out != JANET_HANDLE_NONE) CloseHandle(pipe_out);
if (pipe_err != JANET_HANDLE_NONE) CloseHandle(pipe_err);
os_execute_cleanup(envp, NULL);
if (cp_failed) {
janet_panic("failed to create process");
}
pHandle = processInfo.hProcess;
tHandle = processInfo.hThread;
#else
/* Result */
int status = 0;
const char **child_argv = janet_smalloc(sizeof(char *) * ((size_t) exargs.len + 1));
for (int32_t i = 0; i < exargs.len; i++)
child_argv[i] = janet_getcstring(exargs.items, i);
child_argv[exargs.len] = NULL;
/* Coerce to form that works for spawn. I'm fairly confident no implementation
* of posix_spawn would modify the argv array passed in. */
char *const *cargv = (char *const *)child_argv;
if (use_environ) {
janet_lock_environ();
}
/* exec mode */
if (mode == JANET_EXECUTE_EXEC) {
#ifdef JANET_WINDOWS
janet_panic("not supported on windows");
#else
int status;
if (!use_environ) {
environ = envp;
}
do {
if (janet_flag_at(flags, 1)) {
status = execvp(cargv[0], cargv);
} else {
status = execv(cargv[0], cargv);
}
} while (status == -1 && errno == EINTR);
janet_panicf("%p: %s", cargv[0], strerror(errno ? errno : ENOENT));
#endif
}
/* Use posix_spawn to spawn new process */
/* Posix spawn setup */
posix_spawn_file_actions_t actions;
posix_spawn_file_actions_init(&actions);
if (pipe_in != JANET_HANDLE_NONE) {
posix_spawn_file_actions_adddup2(&actions, pipe_in, 0);
posix_spawn_file_actions_addclose(&actions, pipe_in);
} else if (new_in != JANET_HANDLE_NONE && new_in != 0) {
posix_spawn_file_actions_adddup2(&actions, new_in, 0);
if (new_in != new_out && new_in != new_err)
posix_spawn_file_actions_addclose(&actions, new_in);
}
if (pipe_out != JANET_HANDLE_NONE) {
posix_spawn_file_actions_adddup2(&actions, pipe_out, 1);
posix_spawn_file_actions_addclose(&actions, pipe_out);
} else if (new_out != JANET_HANDLE_NONE && new_out != 1) {
posix_spawn_file_actions_adddup2(&actions, new_out, 1);
if (new_out != new_err)
posix_spawn_file_actions_addclose(&actions, new_out);
}
if (pipe_err != JANET_HANDLE_NONE) {
posix_spawn_file_actions_adddup2(&actions, pipe_err, 2);
posix_spawn_file_actions_addclose(&actions, pipe_err);
} else if (new_err != JANET_HANDLE_NONE && new_err != 2) {
posix_spawn_file_actions_adddup2(&actions, new_err, 2);
posix_spawn_file_actions_addclose(&actions, new_err);
}
pid_t pid;
if (janet_flag_at(flags, 1)) {
status = posix_spawnp(&pid,
child_argv[0], &actions, NULL, cargv,
use_environ ? environ : envp);
} else {
status = posix_spawn(&pid,
child_argv[0], &actions, NULL, cargv,
use_environ ? environ : envp);
}
posix_spawn_file_actions_destroy(&actions);
if (pipe_in != JANET_HANDLE_NONE) close(pipe_in);
if (pipe_out != JANET_HANDLE_NONE) close(pipe_out);
if (pipe_err != JANET_HANDLE_NONE) close(pipe_err);
if (use_environ) {
janet_unlock_environ();
}
os_execute_cleanup(envp, child_argv);
if (status) {
/* correct for macos bug where errno is not set */
janet_panicf("%p: %s", argv[0], strerror(errno ? errno : ENOENT));
}
#endif
JanetProc *proc = janet_abstract(&ProcAT, sizeof(JanetProc));
proc->return_code = -1;
#ifdef JANET_WINDOWS
proc->pHandle = pHandle;
proc->tHandle = tHandle;
#else
proc->pid = pid;
#endif
proc->in = NULL;
proc->out = NULL;
proc->err = NULL;
proc->flags = pipe_owner_flags;
if (janet_flag_at(flags, 2)) {
proc->flags |= JANET_PROC_ERROR_NONZERO;
}
if (is_spawn) {
/* Only set up pointers to stdin, stdout, and stderr if os/spawn. */
if (new_in != JANET_HANDLE_NONE) {
proc->in = get_stdio_for_handle(new_in, orig_in, 1);
if (NULL == proc->in) janet_panic("failed to construct proc");
}
if (new_out != JANET_HANDLE_NONE) {
proc->out = get_stdio_for_handle(new_out, orig_out, 0);
if (NULL == proc->out) janet_panic("failed to construct proc");
}
if (new_err != JANET_HANDLE_NONE) {
proc->err = get_stdio_for_handle(new_err, orig_err, 0);
if (NULL == proc->err) janet_panic("failed to construct proc");
}
return janet_wrap_abstract(proc);
} else {
#ifdef JANET_EV
os_proc_wait_impl(proc);
#else
return os_proc_wait_impl(proc);
#endif
}
}