Invent systemvpe() function

It goes 5x faster than system() and it's safer too.

libc/cosmo.h

@@ -4,6 +4,7 @@
 COSMOPOLITAN_C_START_
 
 errno_t cosmo_once(_Atomic(uint32_t) *, void (*)(void));
+int systemvpe(const char *, char *const[], char *const[]);
 
 COSMOPOLITAN_C_END_
 #endif /* !(__ASSEMBLER__ + __LINKER__ + 0) */

libc/stdio/system.c

@@ -34,20 +34,37 @@
 /**
  * Launches program with system command interpreter.
  *
- * This embeds the Cosmopolitan Command Interpreter which provides
- * Bourne-like syntax on all platforms including Windows.
+ * This implementation embeds the Cosmopolitan Command Interpreter which
+ * provides Bourne-like syntax on all platforms, including Windows. Many
+ * builtin commands are included, e.g. exit, cd, rm, [, cat, wait, exec,
+ * env, echo, read, true, test, kill, touch, rmdir, mkdir, false, mktemp
+ * and usleep. It's also possible to __static_yoink() the symbols `_tr`,
+ * `_sed`, `_awk`, and `_curl` for the tr, sed, awk and curl commands if
+ * you're using the Cosmopolitan mono-repo.
+ *
+ * If you just have a program name and arguments, and you don't need the
+ * full power of a UNIX-like shell, then consider using the Cosmopolitan
+ * provided API systemvpe() instead. It provides a safer alternative for
+ * variable arguments than shell script escaping. It lets you clean your
+ * environment variables, for even more safety. Finally it's 10x faster.
+ *
+ * It's important to check the returned status code. For example, if you
+ * press CTRL-C while running your program you'll expect it to terminate
+ * however that won't be the case if the SIGINT gets raised while inside
+ * the system() function. If the child process doesn't handle the signal
+ * then this will return e.g. WIFSIGNALED(ws) && WTERMSIG(ws) == SIGINT.
  *
  * @param cmdline is a unix shell script
  * @return -1 if child process couldn't be created, otherwise a wait
  *     status that can be accessed using macros like WEXITSTATUS(s),
  *     WIFSIGNALED(s), WTERMSIG(s), etc.
+ * @see systemve()
  * @threadsafe
  */
 int system(const char *cmdline) {
   int pid, wstatus;
   sigset_t chldmask, savemask;
   if (!cmdline) return 1;
-  BLOCK_CANCELLATIONS;
   sigemptyset(&chldmask);
   sigaddset(&chldmask, SIGINT);
   sigaddset(&chldmask, SIGQUIT);
@@ -65,16 +82,17 @@ int system(const char *cmdline) {
     sigemptyset(&ignore.sa_mask);
     sigaction(SIGINT, &ignore, &saveint);
     sigaction(SIGQUIT, &ignore, &savequit);
+    BLOCK_CANCELLATIONS;
     while (wait4(pid, &wstatus, 0, 0) == -1) {
       if (errno != EINTR) {
         wstatus = -1;
         break;
       }
     }
+    ALLOW_CANCELLATIONS;
     sigaction(SIGQUIT, &savequit, 0);
     sigaction(SIGINT, &saveint, 0);
   }
   sigprocmask(SIG_SETMASK, &savemask, 0);
-  ALLOW_CANCELLATIONS;
   return wstatus;
 }

libc/stdio/systemvpe.c

@@ -0,0 +1,89 @@
+/*-*- 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 2023 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/blockcancel.internal.h"
+#include "libc/calls/calls.h"
+#include "libc/calls/struct/rusage.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/stdio.h"
+#include "libc/sysv/consts/sig.h"
+
+/**
+ * Executes program and waits for it to complete, e.g.
+ *
+ *     systemvpe("ls", (char *[]){"ls", dir, 0}, environ);
+ *
+ * This function is designed to do the same thing as system() except
+ * rather than taking a shell script argument it accepts an array of
+ * strings which are safely passed directly to execve().
+ *
+ * This function is 5x faster than system() and generally safer, for
+ * most command running use cases that don't need to control the i/o
+ * file descriptors.
+ *
+ * @param prog is path searched (if it doesn't contain a slash) from
+ *     the $PATH environment variable in `environ` (not your `envp`)
+ * @return -1 if child process couldn't be created, otherwise a wait
+ *     status that can be accessed using macros like WEXITSTATUS(s),
+ *     WIFSIGNALED(s), WTERMSIG(s), etc.
+ * @see system()
+ * @threadsafe
+ */
+int systemvpe(const char *prog, char *const argv[], char *const envp[]) {
+  char *exe;
+  int pid, wstatus;
+  char pathbuf[PATH_MAX + 1];
+  sigset_t chldmask, savemask;
+  if (!(exe = commandv(prog, pathbuf, sizeof(pathbuf)))) {
+    return -1;
+  }
+  sigemptyset(&chldmask);
+  sigaddset(&chldmask, SIGINT);
+  sigaddset(&chldmask, SIGQUIT);
+  sigaddset(&chldmask, SIGCHLD);
+  sigprocmask(SIG_BLOCK, &chldmask, &savemask);
+  if (!(pid = vfork())) {
+    sigprocmask(SIG_SETMASK, &savemask, 0);
+    execve(prog, argv, envp);
+    _Exit(127);
+  } else if (pid == -1) {
+    wstatus = -1;
+  } else {
+    struct sigaction ignore, saveint, savequit;
+    ignore.sa_flags = 0;
+    ignore.sa_handler = SIG_IGN;
+    sigemptyset(&ignore.sa_mask);
+    sigaction(SIGINT, &ignore, &saveint);
+    sigaction(SIGQUIT, &ignore, &savequit);
+    BLOCK_CANCELLATIONS;
+    while (wait4(pid, &wstatus, 0, 0) == -1) {
+      if (errno != EINTR) {
+        wstatus = -1;
+        break;
+      }
+    }
+    ALLOW_CANCELLATIONS;
+    sigaction(SIGQUIT, &savequit, 0);
+    sigaction(SIGINT, &saveint, 0);
+  }
+  sigprocmask(SIG_SETMASK, &savemask, 0);
+  return wstatus;
+}

test/libc/calls/sigaction_test.c

@@ -19,6 +19,7 @@
 #include "libc/calls/struct/sigaction.h"
 #include "libc/calls/calls.h"
 #include "libc/calls/struct/rusage.h"
+#include "libc/calls/struct/sigaction.h"
 #include "libc/calls/struct/siginfo.h"
 #include "libc/calls/struct/sigset.h"
 #include "libc/calls/struct/sigset.internal.h"
@@ -248,3 +249,19 @@ TEST(uc_sigmask, signalHandlerCanChangeSignalMaskOfTrappedThread) {
   sigdelset(&want, SIGUSR1);
   ASSERT_SYS(0, 0, sigprocmask(SIG_SETMASK, &want, 0));
 }
+
+TEST(sig_ign, discardsPendingSignalsEvenIfBlocked) {
+  sigset_t block, oldmask;
+  struct sigaction sa, oldsa;
+  ASSERT_SYS(0, 0, sigemptyset(&block));
+  ASSERT_SYS(0, 0, sigaddset(&block, SIGUSR1));
+  ASSERT_SYS(0, 0, sigprocmask(SIG_BLOCK, &block, &oldmask));
+  raise(SIGUSR1);  // enqueue
+  sa.sa_flags = 0;
+  sa.sa_handler = SIG_IGN;
+  ASSERT_SYS(0, 0, sigemptyset(&sa.sa_mask));
+  ASSERT_SYS(0, 0, sigaction(SIGUSR1, &sa, &oldsa));  // discard
+  ASSERT_SYS(0, 0, sigprocmask(SIG_UNBLOCK, &block, 0));
+  ASSERT_SYS(0, 0, sigaction(SIGUSR1, &oldsa, 0));
+  ASSERT_SYS(0, 0, sigprocmask(SIG_SETMASK, &oldmask, 0));
+}

test/libc/stdio/system_test.c

@@ -17,6 +17,7 @@
 │ PERFORMANCE OF THIS SOFTWARE.                                                │
 ╚─────────────────────────────────────────────────────────────────────────────*/
 #include "libc/calls/calls.h"
+#include "libc/cosmo.h"
 #include "libc/dce.h"
 #include "libc/mem/gc.h"
 #include "libc/mem/gc.internal.h"
@@ -243,6 +244,8 @@ int system2(const char *);
 BENCH(system, bench) {
   testlib_extract("/zip/echo.com", "echo.com", 0755);
   EZBENCH2("system cmd", donothing, system("./echo.com hi >/dev/null"));
+  EZBENCH2("systemvpe cmd", donothing,
+           systemvpe("./echo.com", (char *[]){"./echo.com", "hi", 0}, 0));
   EZBENCH2("cocmd echo", donothing, system("echo hi >/dev/null"));
   EZBENCH2("cocmd exit", donothing, system("exit"));
 }