cosmopolitan/examples/subprocess.c

61 lines
2.4 KiB
C

#if 0
/*─────────────────────────────────────────────────────────────────╗
│ To the extent possible under law, Justine Tunney has waived │
│ all copyright and related or neighboring rights to this file, │
│ as it is written in the following disclaimers: │
│ • http://unlicense.org/ │
│ • http://creativecommons.org/publicdomain/zero/1.0/ │
╚─────────────────────────────────────────────────────────────────*/
#endif
#include "libc/alg/alg.h"
#include "libc/calls/calls.h"
#include "libc/calls/hefty/spawn.h"
#include "libc/fmt/conv.h"
#include "libc/limits.h"
#include "libc/log/check.h"
#include "libc/runtime/gc.h"
#include "libc/stdio/stdio.h"
#include "libc/sysv/consts/fileno.h"
#include "libc/x/x.h"
const char kProgram[] = "o/default/examples/hello.com";
int main(int argc, char *argv[]) {
/**
* Runs make if hello.com doesn't exist.
*
* 1. gc() automates calling free() on return.
* 2. xasprintf("foo %s", "bar") is our version of "foo %s" % ("bar")
* 3. Demonstrates correct escaping for bourne shell
*/
if (!fileexists(kProgram)) {
system(gc(xasprintf("%s '%s'", "make -j4",
gc(replacestr(kProgram, "'", "'\"'\"'")))));
}
/**
* Our version of subprocess.Popen
* 1. Doesn't require fork() so pain-free on NT
* 2. Google checks are like assert() but better
*/
ssize_t transferred;
int child, wstatus, procfds[3] = {STDIN_FILENO, -1, STDERR_FILENO};
CHECK_NE(-1,
(child = spawnve(0, procfds, /* run w/o shell */ kProgram,
(char *const[]){/* argv[0] */ basename(kProgram),
/* argv[1] */ "boop",
/* sentinel */ NULL},
environ)));
printf("%s %s: ", kProgram, "says");
fflush(stdout);
for (;;) {
transferred = copyfd(procfds[1], NULL, fileno(stdout), NULL, INT_MAX, 0);
CHECK_NE(-1, transferred);
if (!transferred) break;
}
CHECK_NE(-1, waitpid(child, &wstatus, 0));
CHECK_EQ(0, WEXITSTATUS(wstatus));
return 0;
}