Init HEAD master

1 files changed, 115 insertions, 0 deletions

diff --git a/stdio/spawn.c b/stdio/spawn.c
new file mode 100644
index 0000000..5dc3980
--- /dev/null
+++ b/stdio/spawn.c
@@ -0,0 +1,115 @@
+/*-*- 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 2021 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/calls/scheduler.h"
+#include "libc/calls/sigbits.h"
+#include "libc/calls/struct/sigaction.h"
+#include "libc/errno.h"
+#include "libc/fmt/fmt.h"
+#include "libc/stdio/spawn.h"
+#include "libc/stdio/spawna.internal.h"
+#include "libc/str/str.h"
+
+/**
+ * Spawns process the POSIX way.
+ *
+ * @param pid is non-NULL and will be set to child pid in parent
+ * @param path of executable that is not PATH searched
+ * @return 0 on success or error number on failure
+ */
+int posix_spawn(int *pid, const char *path,
+                const posix_spawn_file_actions_t *file_actions,
+                const posix_spawnattr_t *attrp, char *const argv[],
+                char *const envp[]) {
+  unsigned mode;
+  sigset_t allsigs;
+  struct sigaction dfl;
+  char *p, *q, opath[PATH_MAX];
+  int s, fd, newfd, oflag, tempfd;
+  if (!(*pid = vfork())) {
+    if (attrp) {
+      if (attrp->posix_attr_flags & POSIX_SPAWN_SETPGROUP) {
+        if (setpgid(0, attrp->posix_attr_pgroup)) _exit(127);
+      }
+      if (attrp->posix_attr_flags & POSIX_SPAWN_SETSIGMASK) {
+        sigprocmask(SIG_SETMASK, &attrp->posix_attr_sigmask, NULL);
+      }
+      if (attrp->posix_attr_flags & POSIX_SPAWN_RESETIDS) {
+        setuid(getuid());
+        setgid(getgid());
+      }
+      if (attrp->posix_attr_flags & POSIX_SPAWN_SETSIGDEF) {
+        dfl.sa_handler = SIG_DFL;
+        dfl.sa_flags = 0;
+        sigfillset(&allsigs);
+        for (s = 0; sigismember(&allsigs, s); s++) {
+          if (sigismember(&attrp->posix_attr_sigdefault, s)) {
+            if (sigaction(s, &dfl, NULL) == -1) _exit(127);
+          }
+        }
+      }
+    }
+    if (file_actions) {
+      for (p = *file_actions; *p; p = strchr(p, ')') + 1) {
+        if (!strncmp(p, "close(", 6)) {
+          if (sscanf(p + 6, "%d)", &fd) != 1) _exit(127);
+          if (close(fd) == -1) _exit(127);
+        } else if (!strncmp(p, "dup2(", 5)) {
+          if (sscanf(p + 5, "%d,%d)", &fd, &newfd) != 2) _exit(127);
+          if (dup2(fd, newfd) == -1) _exit(127);
+        } else if (!strncmp(p, "open(", 5)) {
+          if (sscanf(p + 5, "%d,", &fd) != 1) _exit(127);
+          p = strchr(p, ',') + 1;
+          q = strchr(p, '*');
+          if (!q || q - p + 1 > PATH_MAX) _exit(127);
+          strncpy(opath, p, q - p);
+          opath[q - p] = '\0';
+          if (sscanf(q + 1, "%o,%o)", &oflag, &mode) != 2) _exit(127);
+          if (close(fd) == -1 && errno != EBADF) _exit(127);
+          tempfd = open(opath, oflag, mode);
+          if (tempfd == -1) _exit(127);
+          if (tempfd != fd) {
+            if (dup2(tempfd, fd) == -1) _exit(127);
+            if (close(tempfd) == -1) _exit(127);
+          }
+        } else {
+          _exit(127);
+        }
+      }
+    }
+    if (attrp) {
+      if (attrp->posix_attr_flags & POSIX_SPAWN_SETSCHEDULER) {
+        if (sched_setscheduler(0, attrp->posix_attr_schedpolicy,
+                               &attrp->posix_attr_schedparam) == -1) {
+          _exit(127);
+        }
+      }
+      if (attrp->posix_attr_flags & POSIX_SPAWN_SETSCHEDPARAM) {
+        if (sched_setparam(0, &attrp->posix_attr_schedparam) == -1) {
+          _exit(127);
+        }
+      }
+    }
+    execve(path, argv, envp);
+    _exit(127);
+  } else {
+    if (*pid == -1) return errno;
+    return 0;
+  }
+}