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Improve documentation on subprocess API
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amano-kenji committed Feb 7, 2024
1 parent 431ecd3 commit ad75994
Showing 1 changed file with 25 additions and 16 deletions.
41 changes: 25 additions & 16 deletions src/core/os.c
Original file line number Diff line number Diff line change
Expand Up @@ -618,7 +618,10 @@ os_proc_wait_impl(JanetProc *proc) {

JANET_CORE_FN(os_proc_wait,
"(os/proc-wait proc)",
"Suspend the current fiber until the subprocess completes. Returns the subprocess return code.") {
"Suspend the current fiber until the subprocess completes. Returns the subprocess return code. "
"os/proc-wait cannot be called twice on the same process. If os/proc-wait is cancelled with an error, "
"os/proc-wait still finishes in the background. Only after os/proc-wait finishes, a process is cleaned "
"up by the operating system. Thus, a process becomes a zombie process if os/proc-wait is not called.") {
janet_fixarity(argc, 1);
JanetProc *proc = janet_getabstract(argv, 0, &ProcAT);
#ifdef JANET_EV
Expand Down Expand Up @@ -729,10 +732,11 @@ static int get_signal_kw(const Janet *argv, int32_t n) {
JANET_CORE_FN(os_proc_kill,
"(os/proc-kill proc &opt wait signal)",
"Kill a subprocess by sending SIGKILL to it on posix systems, or by closing the process "
"handle on windows. If `wait` is truthy, will wait for the process to finish and "
"returns the exit code. Otherwise, returns `proc`. If signal is specified send it instead."
"Signal keywords are named after their C counterparts but in lowercase with the leading "
"`SIG` stripped. Signals are ignored on windows.") {
"handle on windows. If os/proc-wait already finished for proc, os/proc-kill raises an error. After "
"sending signal to proc, if `wait` is truthy, will wait for the process to finish and return the exit "
"code by calling os/proc-wait. Otherwise, returns `proc`. If signal is specified, send it instead. "
"Signal keywords are named after their C counterparts but in lowercase with the leading `SIG` stripped. "
"Signals are ignored on windows.") {
janet_arity(argc, 1, 3);
JanetProc *proc = janet_getabstract(argv, 0, &ProcAT);
if (proc->flags & JANET_PROC_WAITED) {
Expand Down Expand Up @@ -771,8 +775,8 @@ JANET_CORE_FN(os_proc_kill,

JANET_CORE_FN(os_proc_close,
"(os/proc-close proc)",
"Wait on a process if it has not been waited on, and close pipes created by `os/spawn` "
"if they have not been closed. Returns nil.") {
"Close pipes created by `os/spawn` if they have not been closed. Then, if os/proc-wait was not already "
"called on proc, os/proc-wait is called on it. Returns nil.") {
janet_fixarity(argc, 1);
JanetProc *proc = janet_getabstract(argv, 0, &ProcAT);
#ifdef JANET_EV
Expand Down Expand Up @@ -1377,21 +1381,26 @@ JANET_CORE_FN(os_execute,
"* :d - Don't try and terminate the process on garbage collection (allow spawning zombies).\n"
"`env` is a table or struct mapping environment variables to values. It can also "
"contain the keys :in, :out, and :err, which allow redirecting stdio in the subprocess. "
"These arguments should be core/file values. "
"Returns the exit status of the program.") {
":in, :out, and :err should be core/file values or core/stream values. core/file values and core/stream "
"values passed to :in, :out, and :err should be closed manually because os/execute doesn't close them. "
"Returns the exit code of the program.") {
return os_execute_impl(argc, argv, JANET_EXECUTE_EXECUTE);
}

JANET_CORE_FN(os_spawn,
"(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 to 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 returned value `proc` has the fields :in, :out, :err, :return-code, and "
"the additional field :pid on unix-like platforms. Use `(os/proc-wait proc)` to rejoin the "
"subprocess or `(os/proc-kill proc)`.") {
"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 returned value `proc` has the fields :in, :out, "
":err, and the additional field :pid on unix-like platforms. `(os/proc-wait proc)` must be called to "
"rejoin the subprocess. After `(os/proc-wait proc)` finishes, proc gains a new field, :return-code. "
"If :x flag is passed to os/spawn, non-zero exit code will cause os/proc-wait to raise an error. "
"If pipe streams created with :pipe keyword are not closed in time, janet can run out of file "
"descriptors. They can be closed individually, or `os/proc-close` can close all pipe streams on proc. "
"If pipe streams aren't read before `os/proc-wait` finishes, then pipe buffers become full, and the "
"process cannot finish because the process cannot print more on pipe buffers which are already full. "
"If the process cannot finish, os/proc-wait cannot finish, either.") {
return os_execute_impl(argc, argv, JANET_EXECUTE_SPAWN);
}

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