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/runtime/clone.c

@@ -644,7 +644,7 @@ errno_t clone(void *func, void *stk, size_t stksz, int flags, void *arg,
   if (!func) {
     rc = EINVAL;
   } else if (!IsTiny() &&
-             ((flags & CLONE_VM) && (stksz < PAGESIZE || (stksz & 15)))) {
+             ((flags & CLONE_VM) && (stksz < 4096 || (stksz & 15)))) {
     rc = EINVAL;
   } else if (IsAsan() &&
              (((flags & CLONE_SETTLS) && !__asan_is_valid(tls, 64)) ||

libc/runtime/cosmo2.c

@@ -148,7 +148,7 @@ textstartup void cosmo(long *sp, struct Syslib *m1) {
 #endif
 
   // initialize file system
-  __init_fds();
+  __init_fds(argc, argv, envp);
 
   // set helpful globals
   __argc = argc;

libc/runtime/enable_tls.c

@@ -102,11 +102,11 @@ textstartup void __enable_tls(void) {
 
   // Here's the layout we're currently using:
   //
-  //         .balign PAGESIZE
+  //         .balign 4096
   //     _tdata_start:
   //         .tdata
   //         _tdata_size = . - _tdata_start
-  //         .balign PAGESIZE
+  //         .balign 4096
   //     _tbss_start:
   //     _tdata_start + _tbss_offset:
   //         .tbss

libc/runtime/fork-nt.c

@@ -52,6 +52,7 @@
 #include "libc/runtime/memtrack.internal.h"
 #include "libc/runtime/runtime.h"
 #include "libc/runtime/symbols.internal.h"
+#include "libc/sock/internal.h"
 #include "libc/str/str.h"
 #include "libc/sysv/consts/map.h"
 #include "libc/sysv/consts/o.h"
@@ -68,7 +69,9 @@ bool32 __onntconsoleevent_nt(uint32_t);
 void kmalloc_unlock(void);
 
 static textwindows wontreturn void AbortFork(const char *func) {
-  STRACE("fork() %s() failed %d", func, GetLastError());
+#ifdef SYSDEBUG
+  kprintf("fork() %s() failed with win32 error %d\n", func, GetLastError());
+#endif
   ExitProcess(177);
 }
 
@@ -104,7 +107,15 @@ static dontinline textwindows bool ForkIo2(int64_t h, void *buf, size_t n,
 }
 
 static dontinline textwindows bool WriteAll(int64_t h, void *buf, size_t n) {
-  return ForkIo2(h, buf, n, WriteFile, "WriteFile", false);
+  bool ok;
+  ok = ForkIo2(h, buf, n, WriteFile, "WriteFile", false);
+#ifdef SYSDEBUG
+  if (!ok) {
+    kprintf("failed to write %zu bytes to forked child: %d\n", n,
+            GetLastError());
+  }
+#endif
+  return ok;
 }
 
 static textwindows dontinline void ReadOrDie(int64_t h, void *buf, size_t n) {
@@ -320,8 +331,13 @@ textwindows int sys_fork_nt(uint32_t dwCreationFlags) {
         }
         for (i = 0; i < _mmi.i && ok; ++i) {
           if ((_mmi.p[i].flags & MAP_TYPE) != MAP_SHARED) {
-            ok = WriteAll(writer, (void *)((uint64_t)_mmi.p[i].x << 16),
-                          _mmi.p[i].size);
+            uint32_t op;
+            char *p = (char *)((uint64_t)_mmi.p[i].x << 16);
+            // XXX: forking destroys thread guard pages currently
+            VirtualProtect(
+                p, _mmi.p[i].size,
+                __prot2nt(_mmi.p[i].prot | PROT_READ, _mmi.p[i].iscow), &op);
+            ok = WriteAll(writer, p, _mmi.p[i].size);
           }
         }
         if (ok) ok = WriteAll(writer, __data_start, __data_end - __data_start);

libc/runtime/internal.h

@@ -51,7 +51,7 @@ int __inflate(void *, size_t, const void *, size_t);
 void *_Mmap(void *, size_t, int, int, int, int64_t) dontasan;
 int _Munmap(char *, size_t) dontasan;
 void __on_arithmetic_overflow(void);
-void __init_fds(void);
+void __init_fds(int, char **, char **);
 
 COSMOPOLITAN_C_END_
 #endif /* !(__ASSEMBLER__ + __LINKER__ + 0) */

libc/runtime/memtrack.internal.h

@@ -141,10 +141,6 @@ forceinline pureconst bool IsShadowFrame(int x) {
   return 0x7fff <= x && x < 0x10008000;
 }
 
-forceinline pureconst bool IsArenaFrame(int x) {
-  return 0x5004 <= x && x <= 0x7ffb;
-}
-
 forceinline pureconst bool IsStaticStackFrame(int x) {
   intptr_t stack = GetStaticStackAddr(0);
   return (int)(stack >> 16) <= x &&
@@ -192,19 +188,6 @@ forceinline pureconst bool OverlapsImageSpace(const void *p, size_t n) {
   }
 }
 
-forceinline pureconst bool OverlapsArenaSpace(const void *p, size_t n) {
-  intptr_t BegA, EndA, BegB, EndB;
-  if (n) {
-    BegA = (intptr_t)p;
-    EndA = BegA + (n - 1);
-    BegB = 0x50000000;
-    EndB = 0x7ffdffff;
-    return MAX(BegA, BegB) < MIN(EndA, EndB);
-  } else {
-    return 0;
-  }
-}
-
 forceinline pureconst bool OverlapsShadowSpace(const void *p, size_t n) {
   intptr_t BegA, EndA, BegB, EndB;
   if (n) {

libc/runtime/mkstemp.c

@@ -1,54 +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/calls/calls.h"
-#include "libc/intrin/bits.h"
-#include "libc/stdio/rand.h"
-#include "libc/stdio/temp.h"
-#include "libc/str/str.h"
-#include "libc/sysv/consts/o.h"
-#include "libc/sysv/errfuns.h"
-
-/**
- * Creates temporary file name and descriptor, e.g.
- *
- *     char path[PATH_MAX+1];
- *     strlcat(path, kTmpDir, sizeof(path));
- *     strlcat(path, "sauce.XXXXXX", sizeof(path));
- *     close(mkstemp(path));
- *     puts(path);
- *
- * @param template is mutated to replace last six X's with rng
- * @return open file descriptor r + w exclusive or -1 w/ errno
- * @raise EINVAL if `template` didn't end with `XXXXXX`
- */
-int mkstemp(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")) {
-    return einval();
-  }
-  w = _rand64();
-  for (i = 0; i < 6; ++i) {
-    template[n - 6 + i] = "0123456789abcdefghijklmnopqrstuvwxyz"[w % 36];
-    w /= 36;
-  }
-  return open(template, O_RDWR | O_CREAT | O_EXCL, 0600);
-}

libc/runtime/mmap.c

@@ -245,9 +245,10 @@ dontasan inline void *_Mmap(void *addr, size_t size, int prot, int flags,
                             int fd, int64_t off) {
   char *p = addr;
   struct DirectMap dm;
+  size_t requested_size;
   int a, b, i, f, m, n, x;
   bool needguard, clashes;
-  unsigned long guardsize;
+  unsigned long page_size;
   size_t virtualused, virtualneed;
 
   if (VERY_UNLIKELY(!size)) {
@@ -274,11 +275,12 @@ dontasan inline void *_Mmap(void *addr, size_t size, int prot, int flags,
     flags = MAP_SHARED;  // cf. MAP_SHARED_VALIDATE
   }
 
+  requested_size = size;
+  page_size = getauxval(AT_PAGESZ);
   if (flags & MAP_ANONYMOUS) {
     fd = -1;
     off = 0;
     size = ROUNDUP(size, FRAMESIZE);
-    if (IsWindows()) prot |= PROT_WRITE;  // kludge
     if ((flags & MAP_TYPE) == MAP_FILE) {
       STRACE("need MAP_PRIVATE or MAP_SHARED");
       return VIP(einval());
@@ -289,8 +291,8 @@ dontasan inline void *_Mmap(void *addr, size_t size, int prot, int flags,
   } else if (VERY_UNLIKELY(off < 0)) {
     STRACE("mmap negative offset");
     return VIP(einval());
-  } else if (VERY_UNLIKELY(!ALIGNED(off))) {
-    STRACE("mmap off isn't 64kb aligned");
+  } else if (off & ((IsWindows() ? FRAMESIZE : page_size) - 1)) {
+    STRACE("mmap offset isn't properly aligned");
     return VIP(einval());
   } else if (VERY_UNLIKELY(INT64_MAX - size < off)) {
     STRACE("mmap too large");
@@ -326,8 +328,7 @@ dontasan inline void *_Mmap(void *addr, size_t size, int prot, int flags,
         OnUnrecoverableMmapError("FIXED UNTRACK FAILED");
       }
     }
-  } else if (p && !clashes && !OverlapsArenaSpace(p, size) &&
-             !OverlapsShadowSpace(p, size)) {
+  } else if (p && !clashes && !OverlapsShadowSpace(p, size)) {
     x = FRAME(p);
   } else if (!Automap(n, a, &x)) {
     STRACE("automap has no room for %d frames with %d alignment", n, a);
@@ -335,7 +336,6 @@ dontasan inline void *_Mmap(void *addr, size_t size, int prot, int flags,
   }
 
   needguard = false;
-  guardsize = getauxval(AT_PAGESZ);
   p = (char *)ADDR_32_TO_48(x);
   if ((f & MAP_TYPE) == MAP_STACK) {
     if (~f & MAP_ANONYMOUS) {
@@ -374,11 +374,15 @@ dontasan inline void *_Mmap(void *addr, size_t size, int prot, int flags,
       if ((dm = sys_mmap(p + size - SIGSTKSZ, SIGSTKSZ, prot,
                          f | MAP_GROWSDOWN_linux, fd, off))
               .addr != MAP_FAILED) {
-        npassert(sys_mmap(p, guardsize, PROT_NONE,
+        npassert(sys_mmap(p, page_size, PROT_NONE,
                           MAP_FIXED | MAP_PRIVATE | MAP_ANONYMOUS, -1, 0)
                      .addr == p);
         dm.addr = p;
-        return FinishMemory(p, size, prot, flags, fd, off, f, x, n, dm);
+        p = FinishMemory(p, size, prot, flags, fd, off, f, x, n, dm);
+        if (IsAsan() && p != MAP_FAILED) {
+          __asan_poison(p, page_size, kAsanStackOverflow);
+        }
+        return p;
       } else if (errno == ENOTSUP) {
         // WSL doesn't support MAP_GROWSDOWN
         needguard = true;
@@ -399,14 +403,14 @@ dontasan inline void *_Mmap(void *addr, size_t size, int prot, int flags,
   }
 
   if (p != MAP_FAILED) {
+    if (IsAsan()) {
+      __asan_poison(p + requested_size, size - requested_size,
+                    kAsanMmapSizeOverrun);
+    }
     if (needguard) {
-      if (!IsWindows()) {
-        // make windows fork() code simpler
-        mprotect(p, guardsize, PROT_NONE);
-      }
+      unassert(!mprotect(p, page_size, PROT_NONE));
       if (IsAsan()) {
-        __repstosb((void *)(((intptr_t)p >> 3) + 0x7fff8000),
-                   kAsanStackOverflow, guardsize / 8);
+        __asan_poison(p, page_size, kAsanStackOverflow);
       }
     }
   }
@@ -415,7 +419,7 @@ dontasan inline void *_Mmap(void *addr, size_t size, int prot, int flags,
 }
 
 /**
- * Beseeches system for page-table entries, e.g.
+ * Creates virtual memory, e.g.
  *
  *     char *m;
  *     m = mmap(NULL, FRAMESIZE, PROT_READ | PROT_WRITE,
@@ -430,9 +434,7 @@ dontasan inline void *_Mmap(void *addr, size_t size, int prot, int flags,
  *     needs to be made mandatory because of Windows although you can
  *     use __sys_mmap() to circumvent it on System Five in which case
  *     runtime support services, e.g. asan memory safety, could break
- * @param size must be >0 and needn't be a multiple of FRAMESIZE, but
- *     will be rounded up to FRAMESIZE automatically if MAP_ANONYMOUS
- *     is specified
+ * @param size must be >0 otherwise EINVAL is raised
  * @param prot can have PROT_READ/PROT_WRITE/PROT_EXEC/PROT_NONE/etc.
  * @param flags should have one of the following masked by `MAP_TYPE`
  *     - `MAP_FILE` in which case `MAP_ANONYMOUS` shouldn't be used
@@ -459,8 +461,8 @@ dontasan inline void *_Mmap(void *addr, size_t size, int prot, int flags,
  * @param fd is an open()'d file descriptor, whose contents shall be
  *     made available w/ automatic reading at the chosen address
  * @param off specifies absolute byte index of fd's file for mapping,
- *     should be zero if MAP_ANONYMOUS is specified, and sadly needs
- *     to be 64kb aligned too
+ *     should be zero if MAP_ANONYMOUS is specified, which SHOULD be
+ *     aligned to FRAMESIZE
  * @return virtual base address of new mapping, or MAP_FAILED w/ errno
  */
 void *mmap(void *addr, size_t size, int prot, int flags, int fd, int64_t off) {

libc/runtime/mprotect-nt.greg.c

@@ -27,6 +27,7 @@ textwindows int sys_mprotect_nt(void *addr, size_t size, int prot) {
   uint32_t op;
   char *a, *b, *x, *y, *p;
   __mmi_lock();
+  size = (size + 4095) & -4096;
   p = addr;
   i = FindMemoryInterval(&_mmi, (intptr_t)p >> 16);
   if (i == _mmi.i || (!i && p + size <= (char *)ADDR_32_TO_48(_mmi.p[0].x))) {
@@ -41,9 +42,14 @@ textwindows int sys_mprotect_nt(void *addr, size_t size, int prot) {
     // we unfortunately must do something similar to this for cow
     for (; i < _mmi.i; ++i) {
       x = (char *)ADDR_32_TO_48(_mmi.p[i].x);
-      y = x + _mmi.p[i].size;
+      y = (char *)ADDR_32_TO_48(_mmi.p[i].y) + 65536;
       if ((x <= p && p < y) || (x < p + size && p + size <= y) ||
           (p < x && y < p + size)) {
+        if (p <= x && p + size >= y) {
+          _mmi.p[i].prot = prot;
+        } else {
+          _mmi.p[i].prot |= prot;
+        }
         a = MIN(MAX(p, x), y);
         b = MAX(MIN(p + size, y), x);
         if (!VirtualProtect(a, b - a, __prot2nt(prot, _mmi.p[i].iscow), &op)) {

libc/runtime/mprotect.c

@@ -23,6 +23,8 @@
 #include "libc/intrin/likely.h"
 #include "libc/intrin/strace.internal.h"
 #include "libc/runtime/internal.h"
+#include "libc/runtime/runtime.h"
+#include "libc/sysv/consts/auxv.h"
 #include "libc/sysv/consts/prot.h"
 #include "libc/sysv/errfuns.h"
 
@@ -41,7 +43,7 @@ int mprotect(void *addr, size_t size, int prot) {
     rc = einval();  // unix checks prot before checking size
   } else if (!size) {
     return 0;  // make new technology consistent with unix
-  } else if (UNLIKELY((intptr_t)addr & 4095)) {
+  } else if (UNLIKELY((intptr_t)addr & (getauxval(AT_PAGESZ) - 1))) {
     rc = einval();  // unix checks prot before checking size
   } else if (!IsWindows()) {
     rc = sys_mprotect(addr, size, prot);