Make more fixes and improvements

- Remove PAGESIZE constant
- Fix realloc() documentation
- Fix ttyname_r() error reporting
- Make forking more reliable on Windows
- Make execvp() a few microseconds faster
- Make system() a few microseconds faster
- Tighten up the socket-related magic numbers
- Loosen restrictions on mmap() offset alignment
- Improve GetProgramExecutableName() with getenv("_")
- Use mkstemp() as basis for mktemp(), tmpfile(), tmpfd()
- Fix flakes in pthread_cancel_test, unix_test, fork_test
- Fix recently introduced futex stack overflow regression
- Let sockets be passed as stdio to subprocesses on Windows
- Improve security of bind() on Windows w/ SO_EXCLUSIVEADDRUSE

libc/stdio/dirstream.c

@@ -285,7 +285,9 @@ DIR *opendir(const char *name) {
           res->zip.offset = GetZipCdirOffset(zip->cdir);
           res->zip.records = GetZipCdirRecords(zip->cdir);
           res->zip.prefix = malloc(zipname.len + 2);
-          memcpy(res->zip.prefix, zipname.path, zipname.len);
+          if (zipname.len) {
+            memcpy(res->zip.prefix, zipname.path, zipname.len);
+          }
           if (zipname.len && res->zip.prefix[zipname.len - 1] != '/') {
             res->zip.prefix[zipname.len++] = '/';
           }
@@ -364,7 +366,9 @@ static struct dirent *readdir_impl(DIR *dir) {
           ent->d_off = dir->zip.offset;
           ent->d_reclen = MIN(n, 255);
           ent->d_type = S_ISDIR(mode) ? DT_DIR : DT_REG;
-          memcpy(ent->d_name, s, ent->d_reclen);
+          if (ent->d_reclen) {
+            memcpy(ent->d_name, s, ent->d_reclen);
+          }
           ent->d_name[ent->d_reclen] = 0;
         } else {
           lastent = (struct dirent *)dir->buf;
@@ -377,7 +381,9 @@ static struct dirent *readdir_impl(DIR *dir) {
             ent->d_off = -1;
             ent->d_reclen = n;
             ent->d_type = DT_DIR;
-            memcpy(ent->d_name, s, ent->d_reclen);
+            if (ent->d_reclen) {
+              memcpy(ent->d_name, s, ent->d_reclen);
+            }
             ent->d_name[ent->d_reclen] = 0;
           }
         }
@@ -474,7 +480,9 @@ errno_t readdir_r(DIR *dir, struct dirent *output, struct dirent **result) {
     return err;
   }
   if (entry) {
-    memcpy(output, entry, entry->d_reclen);
+    if (entry->d_reclen) {
+      memcpy(output, entry, entry->d_reclen);
+    }
   } else {
     output = 0;
   }

libc/stdio/fgets_unlocked.c

@@ -47,7 +47,7 @@ char *fgets_unlocked(char *s, int size, FILE *f) {
         if ((t = memchr(b, '\n', n))) {
           n = t + 1 - b;
         }
-        memcpy(p, b, n);
+        if (n) memcpy(p, b, n);
         f->beg += n;
         size -= n - 1;
         p += n;

libc/stdio/mkostempsm.c

@@ -18,6 +18,7 @@
 ╚─────────────────────────────────────────────────────────────────────────────*/
 #include "libc/assert.h"
 #include "libc/calls/calls.h"
+#include "libc/dce.h"
 #include "libc/errno.h"
 #include "libc/intrin/strace.internal.h"
 #include "libc/runtime/runtime.h"
@@ -39,7 +40,8 @@ int mkostempsmi(char *tpl, int slen, unsigned flags, uint64_t *rando, int mode,
   if (len < wildlen || slen > len - wildlen) return einval();
   char *ss = tpl + len - wildlen - slen;
   npassert(memcmp(ss, WILDCARD, wildlen) == 0);
-  flags = (flags & ~(flags & O_ACCMODE)) | O_RDWR | O_CREAT | O_EXCL;
+  flags = (flags & ~(flags & O_ACCMODE)) | O_RDWR | O_CREAT | O_EXCL |
+          (IsWindows() ? 0x00410000 : 0);
   unsigned attempts = ATTEMPTS;
   do {
     char *p = ss;
@@ -74,8 +76,7 @@ static uint64_t g_mkostemps_reseed;
  *     or -1 w/ errno
  * @see kTmpPath
  */
-dontdiscard int mkostempsm(char *template, int suffixlen, unsigned flags,
-                           int mode) {
+int mkostempsm(char *template, int suffixlen, unsigned flags, int mode) {
   int fd;
   if (g_mkostemps_reseed++ % RESEED == 0) g_mkostemps_rand = _rand64();
   fd = mkostempsmi(template, suffixlen, flags, &g_mkostemps_rand, mode, open);

libc/stdio/mktemp.c

@@ -1,51 +0,0 @@
-/*-*- 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/errno.h"
-#include "libc/intrin/bits.h"
-#include "libc/stdio/rand.h"
-#include "libc/stdio/temp.h"
-#include "libc/str/str.h"
-
-/**
- * Generates temporary filename.
- *
- *     char tmp[14] = "/tmp/hiXXXXXX";
- *     puts(mkstemp(tmp));
- *
- * @param template is mutated to replace last six X's with rng
- * @raise EINVAL if `template` didn't end with `XXXXXX`
- * @return pointer to mutated `template`, or 0 w/ errno
- * @see mkstemp()
- */
-char *mktemp(char *template) {
-  int i, n;
-  uint64_t w;
-  if ((n = strlen(template)) < 6 ||
-      READ16LE(template + n - 2) != READ16LE("XX") ||
-      READ32LE(template + n - 6) != READ32LE("XXXX")) {
-    errno = EINVAL;
-    return 0;
-  }
-  w = _rand64();
-  for (i = 0; i < 6; ++i) {
-    template[n - 6 + i] = "0123456789abcdefghijklmnopqrstuvwxyz"[w % 36];
-    w /= 36;
-  }
-  return template;
-}

libc/stdio/posix_spawn.c

@@ -87,13 +87,13 @@ errno_t posix_spawn(int *pid, const char *path,
       posix_spawnattr_getflags(attrp, &flags);
       if (flags & POSIX_SPAWN_SETSID) {
         if (setsid()) {
-          STRACE("posix_spawn fail #%d", 1);
+          STRACE("posix_spawn fail #%d% m", 1);
           _Exit(127);
         }
       }
       if (flags & POSIX_SPAWN_SETPGROUP) {
         if (setpgid(0, (*attrp)->pgroup)) {
-          STRACE("posix_spawn fail #%d", 1);
+          STRACE("posix_spawn fail #%d% m", 2);
           _Exit(127);
         }
       }
@@ -103,14 +103,14 @@ errno_t posix_spawn(int *pid, const char *path,
       }
       if ((flags & POSIX_SPAWN_RESETIDS) &&
           (setgid(getgid()) || setuid(getuid()))) {
-        STRACE("posix_spawn fail #%d", 2);
+        STRACE("posix_spawn fail #%d% m", 3);
         _Exit(127);
       }
       if (flags & POSIX_SPAWN_SETSIGDEF) {
         for (s = 1; s < 32; s++) {
           if (sigismember(&(*attrp)->sigdefault, s)) {
             if (sigaction(s, &dfl, 0) == -1) {
-              STRACE("posix_spawn fail #%d", 3);
+              STRACE("posix_spawn fail #%d% m", 4);
               _Exit(127);
             }
           }
@@ -119,7 +119,7 @@ errno_t posix_spawn(int *pid, const char *path,
     }
     if (file_actions) {
       if (RunFileActions(*file_actions) == -1) {
-        STRACE("posix_spawn fail #%d", 4);
+        STRACE("posix_spawn fail #%d% m", 5);
         _Exit(127);
       }
     }
@@ -128,21 +128,21 @@ errno_t posix_spawn(int *pid, const char *path,
         posix_spawnattr_getschedpolicy(attrp, &policy);
         posix_spawnattr_getschedparam(attrp, &param);
         if (sched_setscheduler(0, policy, &param) == -1) {
-          STRACE("posix_spawn fail #%d", 5);
+          STRACE("posix_spawn fail #%d% m", 6);
           _Exit(127);
         }
       }
       if (flags & POSIX_SPAWN_SETSCHEDPARAM) {
         posix_spawnattr_getschedparam(attrp, &param);
         if (sched_setparam(0, &param) == -1) {
-          STRACE("posix_spawn fail #%d", 6);
+          STRACE("posix_spawn fail #%d% m", 7);
           _Exit(127);
         }
       }
     }
     if (!envp) envp = environ;
     execve(path, argv, envp);
-    STRACE("posix_spawn fail #%d", 7);
+    STRACE("posix_spawn fail #%d% m", 8);
     _Exit(127);
   } else if (child != -1) {
     if (pid) *pid = child;

libc/stdio/system.c

@@ -46,34 +46,34 @@
 int system(const char *cmdline) {
   int pid, wstatus;
   sigset_t chldmask, savemask;
-  struct sigaction ignore, saveint, savequit;
   if (!cmdline) return 1;
   BLOCK_CANCELLATIONS;
-  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, SIGINT);
+  sigaddset(&chldmask, SIGQUIT);
   sigaddset(&chldmask, SIGCHLD);
   sigprocmask(SIG_BLOCK, &chldmask, &savemask);
   if (!(pid = fork())) {
-    sigaction(SIGINT, &saveint, 0);
-    sigaction(SIGQUIT, &savequit, 0);
     sigprocmask(SIG_SETMASK, &savemask, 0);
     _Exit(_cocmd(3, (char *[]){"system", "-c", cmdline, 0}, environ));
-  } else if (pid != -1) {
+  } 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);
     while (wait4(pid, &wstatus, 0, 0) == -1) {
       if (errno != EINTR) {
         wstatus = -1;
         break;
       }
     }
-  } else {
-    wstatus = -1;
+    sigaction(SIGINT, &saveint, 0);
+    sigaction(SIGQUIT, &savequit, 0);
   }
-  sigaction(SIGINT, &saveint, 0);
-  sigaction(SIGQUIT, &savequit, 0);
   sigprocmask(SIG_SETMASK, &savemask, 0);
   ALLOW_CANCELLATIONS;
   return wstatus;