Initial import

examples/subprocess.c

@@ -0,0 +1,60 @@
+#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/conv/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 cf. xaescapeshq()
+   */
+  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;
+}