Add /dev/fd support to Windows

GNU bash needs this functionality, otherwise it can't do <(cmd...).

Author: jart

libc/calls/fstatat-nt.c

@@ -33,11 +33,27 @@
 #include "libc/sysv/consts/fileno.h"
 #include "libc/sysv/errfuns.h"
 
+static int Atoi(const char *str) {
+  int c;
+  unsigned x = 0;
+  if (!*str) return -1;
+  while ((c = *str++)) {
+    if ('0' <= c && c <= '9') {
+      x *= 10;
+      x += c - '0';
+    } else {
+      return -1;
+    }
+  }
+  return x;
+}
+
 textwindows int sys_fstatat_nt(int dirfd, const char *path, struct stat *st,
                                int flags) {
 
   // handle special files
   if (startswith(path, "/dev/")) {
+    int fd;
     if (!strcmp(path + 5, "tty")) {
       return sys_fstat_nt_special(kFdConsole, st);
     } else if (!strcmp(path + 5, "null")) {
@@ -48,6 +64,8 @@ textwindows int sys_fstatat_nt(int dirfd, const char *path, struct stat *st,
       return sys_fstat_nt(STDOUT_FILENO, st);
     } else if (!strcmp(path + 5, "stderr")) {
       return sys_fstat_nt(STDERR_FILENO, st);
+    } else if (startswith(path + 5, "fd/") && (fd = Atoi(path + 8)) != -1) {
+      return sys_fstat_nt(fd, st);
     } else {
       return enoent();
     }

libc/calls/open-nt.c

@@ -181,10 +181,25 @@ static textwindows int sys_open_nt_dup(int fd, int flags, int mode, int oldfd) {
   }
 }
 
+static int Atoi(const char *str) {
+  int c;
+  unsigned x = 0;
+  if (!*str) return -1;
+  while ((c = *str++)) {
+    if ('0' <= c && c <= '9') {
+      x *= 10;
+      x += c - '0';
+    } else {
+      return -1;
+    }
+  }
+  return x;
+}
+
 textwindows int sys_open_nt(int dirfd, const char *file, uint32_t flags,
                             int32_t mode) {
-  int fd;
   ssize_t rc;
+  int fd, oldfd;
   BLOCK_SIGNALS;
   __fds_lock();
   if (!(flags & _O_CREAT)) mode = 0;
@@ -200,6 +215,9 @@ textwindows int sys_open_nt(int dirfd, const char *file, uint32_t flags,
         rc = sys_open_nt_dup(fd, flags, mode, STDOUT_FILENO);
       } else if (!strcmp(file + 5, "stderr")) {
         rc = sys_open_nt_dup(fd, flags, mode, STDERR_FILENO);
+      } else if (startswith(file + 5, "fd/") &&
+                 (oldfd = Atoi(file + 8)) != -1) {
+        rc = sys_open_nt_dup(fd, flags, mode, oldfd);
       } else {
         rc = enoent();
       }

test/libc/calls/devfd_test.c

@@ -0,0 +1,66 @@
+/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
+│ vi: set et ft=c ts=2 sts=2 sw=2 fenc=utf-8                               :vi │
+╞══════════════════════════════════════════════════════════════════════════════╡
+│ Copyright 2024 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/stat.h"
+#include "libc/dce.h"
+#include "libc/intrin/strace.internal.h"
+#include "libc/str/str.h"
+#include "libc/sysv/consts/o.h"
+#include "libc/testlib/testlib.h"
+#include "libc/x/x.h"
+
+void SetUpOnce(void) {
+  testlib_enable_tmp_setup_teardown();
+}
+
+TEST(devfd, test) {
+  // TODO: What is up with this mysterious ENOENT error?
+  //       The code appears like it should support this.
+  if (IsFreebsd()) return;
+  char buf[8] = {0};
+  struct stat st[2] = {0};
+  ASSERT_SYS(0, 0, xbarf("hello.txt", "bone", -1));
+  ASSERT_SYS(0, 3, open("hello.txt", O_RDONLY));
+  ASSERT_SYS(0, 4, open("/dev/fd/3", O_RDONLY));
+  ASSERT_SYS(0, 4, read(4, buf, 7));
+  ASSERT_STREQ("bone", buf);
+  ASSERT_SYS(0, 0, fstat(3, st));
+  ASSERT_SYS(0, 0, fstat(4, st + 1));
+  ASSERT_EQ(0, memcmp(st, st + 1, sizeof(struct stat)));
+  ASSERT_SYS(0, 0, close(4));
+  ASSERT_SYS(0, 0, close(3));
+}
+
+TEST(devfd, not_DEV_FD_STAT_BROKEN) {
+  // fstat() and stat() are inconsistent on bsd systems
+  // with xnu it only appears to be st_dev that differs
+  if (IsBsd()) return;
+  char buf[8] = {0};
+  struct stat st[2] = {0};
+  ASSERT_SYS(0, 0, xbarf("hello.txt", "bone", -1));
+  ASSERT_SYS(0, 3, open("hello.txt", O_RDONLY));
+  ASSERT_SYS(0, 4, open("/dev/fd/3", O_RDONLY));
+  ASSERT_SYS(0, 4, read(4, buf, 7));
+  ASSERT_STREQ("bone", buf);
+  ASSERT_SYS(0, 0, fstat(3, st));
+  ASSERT_SYS(0, 0, stat("/dev/fd/3", st + 1));
+  ASSERT_EQ(0, memcmp(st, st + 1, sizeof(struct stat)));
+  ASSERT_SYS(0, 0, close(4));
+  ASSERT_SYS(0, 0, close(3));
+}

third_party/bash/README.cosmo

@@ -13,3 +13,4 @@ ORIGIN
 LOCAL CHANGES
 
   - Force disable mkfifo() code
+  - Added runtime check for broken BSD /dev/fd stuff

third_party/bash/config.h

@@ -542,7 +542,7 @@
 #define HAVE_HASH_BANG_EXEC 1
 
 /* Define if you have the /dev/fd devices to map open files into the file system. */
-/* #define HAVE_DEV_FD 1 */
+#define HAVE_DEV_FD 1
 
 /* Defined to /dev/fd or /proc/self/fd (linux). */
 #define DEV_FD_PREFIX "/dev/fd/"
@@ -1160,7 +1160,7 @@
 
 /* #undef GETCWD_BROKEN */
 
-/* #undef DEV_FD_STAT_BROKEN */
+#define DEV_FD_STAT_BROKEN
 
 /* An array implementation that prioritizes speed (O(1) access) over space,
    in array2.c */

third_party/bash/eaccess.c

@@ -1,3 +1,4 @@
+#include "libc/dce.h"
 /* eaccess.c - eaccess replacement for the shell, plus other access functions. */
 
 /* Copyright (C) 2006-2020 Free Software Foundation, Inc.
@@ -93,7 +94,8 @@ sh_stat (path, finfo)
     {
       /* If stating /dev/fd/n doesn't produce the same results as fstat of
 	 FD N, then define DEV_FD_STAT_BROKEN */
-#if !defined (HAVE_DEV_FD) || defined (DEV_FD_STAT_BROKEN)
+//#if !defined (HAVE_DEV_FD) || defined (DEV_FD_STAT_BROKEN)
+if (IsBsd()) {//[jart]
       intmax_t fd;
       int r;
 
@@ -105,7 +107,8 @@ sh_stat (path, finfo)
         }
       errno = ENOENT;
       return (-1);
-#else
+//#else
+} else {//[jart]
   /* If HAVE_DEV_FD is defined, DEV_FD_PREFIX is defined also, and has a
      trailing slash.  Make sure /dev/fd/xx really uses DEV_FD_PREFIX/xx.
      On most systems, with the notable exception of linux, this is
@@ -114,7 +117,8 @@ sh_stat (path, finfo)
       strcpy (pbuf, DEV_FD_PREFIX);
       strcat (pbuf, path + 8);
       return (stat (pbuf, finfo));
-#endif /* !HAVE_DEV_FD */
+//#endif /* !HAVE_DEV_FD */
+}//[jart]
     }
 #if !defined (HAVE_DEV_STDIN)
   else if (STREQN (path, "/dev/std", 8))