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Invent systemvpe() function

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It goes 5x faster than system() and it's safer too.
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Justine Tunney 2023-08-09 00:27:55 -07:00
parent 1a5ef5ba13
commit 50394064d7
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5 changed files with 132 additions and 4 deletions
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libc/stdio/systemvpe.c Normal file
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/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2023 Justine Alexandra Roberts Tunney │
│ │
│ Permission to use, copy, modify, and/or distribute this software for │
│ any purpose with or without fee is hereby granted, provided that the │
│ above copyright notice and this permission notice appear in all copies. │
│ │
│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
│ PERFORMANCE OF THIS SOFTWARE. │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/calls/blockcancel.internal.h"
#include "libc/calls/calls.h"
#include "libc/calls/struct/rusage.h"
#include "libc/calls/struct/sigaction.h"
#include "libc/calls/struct/sigset.h"
#include "libc/errno.h"
#include "libc/runtime/runtime.h"
#include "libc/stdio/stdio.h"
#include "libc/sysv/consts/sig.h"
/**
* Executes program and waits for it to complete, e.g.
*
* systemvpe("ls", (char *[]){"ls", dir, 0}, environ);
*
* This function is designed to do the same thing as system() except
* rather than taking a shell script argument it accepts an array of
* strings which are safely passed directly to execve().
*
* This function is 5x faster than system() and generally safer, for
* most command running use cases that don't need to control the i/o
* file descriptors.
*
* @param prog is path searched (if it doesn't contain a slash) from
* the $PATH environment variable in `environ` (not your `envp`)
* @return -1 if child process couldn't be created, otherwise a wait
* status that can be accessed using macros like WEXITSTATUS(s),
* WIFSIGNALED(s), WTERMSIG(s), etc.
* @see system()
* @threadsafe
*/
int systemvpe(const char *prog, char *const argv[], char *const envp[]) {
char *exe;
int pid, wstatus;
char pathbuf[PATH_MAX + 1];
sigset_t chldmask, savemask;
if (!(exe = commandv(prog, pathbuf, sizeof(pathbuf)))) {
return -1;
}
sigemptyset(&chldmask);
sigaddset(&chldmask, SIGINT);
sigaddset(&chldmask, SIGQUIT);
sigaddset(&chldmask, SIGCHLD);
sigprocmask(SIG_BLOCK, &chldmask, &savemask);
if (!(pid = vfork())) {
sigprocmask(SIG_SETMASK, &savemask, 0);
execve(prog, argv, envp);
_Exit(127);
} else if (pid == -1) {
wstatus = -1;
} else {
struct sigaction ignore, saveint, savequit;
ignore.sa_flags = 0;
ignore.sa_handler = SIG_IGN;
sigemptyset(&ignore.sa_mask);
sigaction(SIGINT, &ignore, &saveint);
sigaction(SIGQUIT, &ignore, &savequit);
BLOCK_CANCELLATIONS;
while (wait4(pid, &wstatus, 0, 0) == -1) {
if (errno != EINTR) {
wstatus = -1;
break;
}
}
ALLOW_CANCELLATIONS;
sigaction(SIGQUIT, &savequit, 0);
sigaction(SIGINT, &saveint, 0);
}
sigprocmask(SIG_SETMASK, &savemask, 0);
return wstatus;
}