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Invent systemvpe() function

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It goes 5x faster than system() and it's safer too.
This commit is contained in:
Justine Tunney 2023-08-09 00:27:55 -07:00
parent 1a5ef5ba13
commit 50394064d7
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GPG key ID: BE714B4575D6E328
5 changed files with 132 additions and 4 deletions
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26
libc/stdio/system.c
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@ -34,20 +34,37 @@
/**
* Launches program with system command interpreter.
*
* This embeds the Cosmopolitan Command Interpreter which provides
* Bourne-like syntax on all platforms including Windows.
* This implementation embeds the Cosmopolitan Command Interpreter which
* provides Bourne-like syntax on all platforms, including Windows. Many
* builtin commands are included, e.g. exit, cd, rm, [, cat, wait, exec,
* env, echo, read, true, test, kill, touch, rmdir, mkdir, false, mktemp
* and usleep. It's also possible to __static_yoink() the symbols `_tr`,
* `_sed`, `_awk`, and `_curl` for the tr, sed, awk and curl commands if
* you're using the Cosmopolitan mono-repo.
*
* If you just have a program name and arguments, and you don't need the
* full power of a UNIX-like shell, then consider using the Cosmopolitan
* provided API systemvpe() instead. It provides a safer alternative for
* variable arguments than shell script escaping. It lets you clean your
* environment variables, for even more safety. Finally it's 10x faster.
*
* It's important to check the returned status code. For example, if you
* press CTRL-C while running your program you'll expect it to terminate
* however that won't be the case if the SIGINT gets raised while inside
* the system() function. If the child process doesn't handle the signal
* then this will return e.g. WIFSIGNALED(ws) && WTERMSIG(ws) == SIGINT.
*
* @param cmdline is a unix shell script
* @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 systemve()
* @threadsafe
*/
int system(const char *cmdline) {
int pid, wstatus;
sigset_t chldmask, savemask;
if (!cmdline) return 1;
BLOCK_CANCELLATIONS;
sigemptyset(&chldmask);
sigaddset(&chldmask, SIGINT);
sigaddset(&chldmask, SIGQUIT);
@ -65,16 +82,17 @@ int system(const char *cmdline) {
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);
ALLOW_CANCELLATIONS;
return wstatus;
}