cosmopolitan/libc/proc/execlp.c
Jōshin 394d998315
Fix vi modelines (#989)
At least in neovim, `│vi:` is not recognized as a modeline because it
has no preceding whitespace. After fixing this, opening a file yields
an error because `net` is not an option. (`noet`, however, is.)
2023-12-05 14:37:54 -08:00

84 lines
3.6 KiB
C

/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│ vi: set noet ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi │
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2020 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/calls.h"
#include "libc/limits.h"
#include "libc/mem/alloca.h"
#include "libc/runtime/runtime.h"
#include "libc/runtime/stack.h"
#include "libc/str/str.h"
#include "libc/sysv/errfuns.h"
/**
* Executes program, with PATH search and current environment.
*
* The current process is replaced with the executed one.
*
* @param prog is program to launch (may be PATH searched)
* @param arg[0] is the name of the program to run
* @param arg[1,n-2] optionally specify program arguments
* @param arg[n-1] is NULL
* @return doesn't return on success, otherwise -1 w/ errno
* @asyncsignalsafe
* @vforksafe
*/
int execlp(const char *prog, const char *arg, ... /*, NULL*/) {
int i;
char *exe;
char **argv;
va_list va, vb;
char pathbuf[PATH_MAX];
// turn varargs into array
va_copy(vb, va);
va_start(va, arg);
for (i = 0; va_arg(va, const char *); ++i) (void)0;
va_end(va);
#pragma GCC push_options
#pragma GCC diagnostic ignored "-Walloca-larger-than="
int nbytes = (i + 2) * sizeof(char *);
if (__get_safe_size(nbytes, 4096) < nbytes) return enomem();
argv = alloca(nbytes);
CheckLargeStackAllocation(argv, nbytes);
#pragma GCC pop_options
va_start(vb, arg);
argv[0] = (char *)arg;
for (i = 1;; ++i) {
if (!(argv[i] = va_arg(vb, char *))) break;
}
va_end(vb);
if (strchr(prog, '/')) {
return execv(prog, argv);
}
// resolve path of executable
if (!(exe = commandv(prog, pathbuf, sizeof(pathbuf)))) {
return -1;
}
// change argv[0] to resolved path if it's ambiguous
// otherwise the program won't have much luck finding itself
if (argv[0] && *prog != '/' && *exe == '/' && !strcmp(prog, argv[0])) {
argv[0] = exe;
}
// execute program
// tail call shouldn't be possible
return execv(exe, argv);
}