Revamp posix_spawn() implementation

2025-05-23 13:52:28 +00:00 · 2022-10-12 05:26:58 -07:00 · 2022-10-12 05:26:58 -07:00 · 0cee831da3
commit 0cee831da3
parent b41f91c658
15 changed files with 383 additions and 215 deletions
--- a/libc/stdio/posix_spawn.c
+++ b/libc/stdio/posix_spawn.c
@ -0,0 +1,121 @@
+/*-*- 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/struct/sigaction.h"
+#include "libc/calls/struct/sigset.h"
+#include "libc/errno.h"
+#include "libc/runtime/runtime.h"
+#include "libc/stdio/posix_spawn.h"
+#include "libc/stdio/posix_spawn.internal.h"
+
+static int RunFileActions(struct _posix_faction *a) {
+  int t;
+  if (!a) return 0;
+  if (RunFileActions(a->next) == -1) return -1;
+  switch (a->action) {
+    case _POSIX_SPAWN_CLOSE:
+      return close(a->fildes);
+    case _POSIX_SPAWN_DUP2:
+      return dup2(a->fildes, a->newfildes);
+    case _POSIX_SPAWN_OPEN:
+      if ((t = open(a->path, a->oflag, a->mode)) == -1) return -1;
+      if (t != a->fildes) {
+        if (dup2(t, a->fildes) == -1) {
+          close(t);
+          return -1;
+        }
+        if (close(t) == -1) {
+          return -1;
+        }
+      }
+      return 0;
+    default:
+      unreachable;
+  }
+}
+
+/**
+ * Spawns process the POSIX way.
+ *
+ * @param pid if non-null shall be set to child pid on success
+ * @param path is resolved path of program which is not `$PATH` searched
+ * @param file_actions specifies close(), dup2(), and open() operations
+ * @param attrp specifies signal masks, user ids, scheduling, etc.
+ * @param envp is environment variables, or `environ` if null
+ * @return 0 on success or error number on failure
+ * @see posix_spawnp() for `$PATH` searching
+ */
+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[]) {
+  int s, child;
+  sigset_t allsigs;
+  struct sigaction dfl;
+  if (!(child = vfork())) {
+    if (attrp && *attrp) {
+      if ((*attrp)->flags & POSIX_SPAWN_SETPGROUP) {
+        if (setpgid(0, (*attrp)->pgroup)) _Exit(127);
+      }
+      if ((*attrp)->flags & POSIX_SPAWN_SETSIGMASK) {
+        sigprocmask(SIG_SETMASK, &(*attrp)->sigmask, 0);
+      }
+      if ((*attrp)->flags & POSIX_SPAWN_RESETIDS) {
+        setuid(getuid());
+        setgid(getgid());
+      }
+      if ((*attrp)->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)->sigdefault, s)) {
+            if (sigaction(s, &dfl, 0) == -1) _Exit(127);
+          }
+        }
+      }
+    }
+    if (file_actions) {
+      if (RunFileActions(*file_actions) == -1) {
+        _Exit(127);
+      }
+    }
+    if (attrp && *attrp) {
+      if ((*attrp)->flags & POSIX_SPAWN_SETSCHEDULER) {
+        if (sched_setscheduler(0, (*attrp)->schedpolicy,
+                               &(*attrp)->schedparam) == -1) {
+          if (errno != ENOSYS) _Exit(127);
+        }
+      }
+      if ((*attrp)->flags & POSIX_SPAWN_SETSCHEDPARAM) {
+        if (sched_setparam(0, &(*attrp)->schedparam) == -1) {
+          if (errno != ENOSYS) _Exit(127);
+        }
+      }
+    }
+    if (!envp) envp = environ;
+    execve(path, argv, envp);
+    _Exit(127);
+  } else if (child != -1) {
+    if (pid) *pid = child;
+    return 0;
+  } else {
+    return errno;
+  }
+}