1 files changed, 76 insertions, 0 deletions
diff --git a/stdio/system.c b/stdio/system.c
new file mode 100644
index 0000000..ef58b0f
--- /dev/null
+++ b/stdio/system.c
@@ -0,0 +1,76 @@
+/*-*- 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 2020 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/bits/weaken.h"
+#include "libc/calls/calls.h"
+#include "libc/calls/sigbits.h"
+#include "libc/calls/struct/sigaction.h"
+#include "libc/dce.h"
+#include "libc/errno.h"
+#include "libc/paths.h"
+#include "libc/runtime/runtime.h"
+#include "libc/stdio/stdio.h"
+#include "libc/str/str.h"
+#include "libc/sysv/consts/ok.h"
+#include "libc/sysv/consts/sig.h"
+
+/**
+ * Launches program with system command interpreter.
+ *
+ * @param cmdline is an interpreted Turing-complete command
+ * @return -1 if child process couldn't be created, otherwise a wait
+ *     status that can be accessed using macros like WEXITSTATUS(s)
+ */
+int system(const char *cmdline) {
+  int pid, wstatus;
+  sigset_t chldmask, savemask;
+  struct sigaction ignore, saveint, savequit;
+  if (!cmdline) {
+    if (IsWindows()) return 1;
+    if (access(_PATH_BSHELL, X_OK) == 0) return 1;
+    return 0;
+  }
+  ignore.sa_flags = 0;
+  ignore.sa_handler = SIG_IGN;
+  sigemptyset(&ignore.sa_mask);
+  sigaction(SIGINT, &ignore, &saveint);
+  sigaction(SIGQUIT, &ignore, &savequit);
+  sigemptyset(&chldmask);
+  sigaddset(&chldmask, SIGCHLD);
+  sigprocmask(SIG_BLOCK, &chldmask, &savemask);
+  if (!(pid = fork())) {
+    sigaction(SIGINT, &saveint, NULL);
+    sigaction(SIGQUIT, &savequit, NULL);
+    sigprocmask(SIG_SETMASK, &savemask, NULL);
+    systemexec(cmdline);
+    _exit(127);
+  } else if (pid != -1) {
+    while (wait4(pid, &wstatus, 0, NULL) == -1) {
+      if (errno != EINTR) {
+        wstatus = -1;
+        break;
+      }
+    }
+  } else {
+    wstatus = -1;
+  }
+  sigaction(SIGINT, &saveint, NULL);
+  sigaction(SIGQUIT, &savequit, NULL);
+  sigprocmask(SIG_SETMASK, &savemask, NULL);
+  return wstatus;
+}