Fix fork() on Windows after chdir()

libc/calls/hefty/fork-nt.c

@@ -22,7 +22,9 @@
 #include "libc/calls/internal.h"
 #include "libc/calls/ntspawn.h"
 #include "libc/fmt/itoa.h"
+#include "libc/macros.h"
 #include "libc/nexgen32e/nt2sysv.h"
+#include "libc/nt/dll.h"
 #include "libc/nt/enum/filemapflags.h"
 #include "libc/nt/enum/pageflags.h"
 #include "libc/nt/enum/startf.h"
@@ -119,6 +121,7 @@ textwindows void WinMainForked(void) {
 textwindows int fork$nt(void) {
   jmp_buf jb;
   int i, rc, pid;
+  char exe[PATH_MAX];
   int64_t reader, writer;
   char *p, buf[21 + 1 + 21 + 1];
   struct NtStartupInfo startinfo;
@@ -137,8 +140,9 @@ textwindows int fork$nt(void) {
       startinfo.hStdInput = g_fds.p[0].handle;
       startinfo.hStdOutput = g_fds.p[1].handle;
       startinfo.hStdError = g_fds.p[2].handle;
-      if (ntspawn(g_argv[0], g_argv, environ, &kNtIsInheritable, NULL, true, 0,
+      GetModuleFileNameA(0, exe, ARRAYLEN(exe));
-                  NULL, &startinfo, &procinfo) != -1) {
+      if (ntspawn(exe, g_argv, environ, &kNtIsInheritable, NULL, true, 0, NULL,
+                  &startinfo, &procinfo) != -1) {
         CloseHandle(reader);
         CloseHandle(procinfo.hThread);
         if (weaken(__sighandrvas) &&

libc/nt/dll.h

@@ -32,6 +32,7 @@ int64_t LoadLibraryEx(const char16_t *lpLibFileName, int64_t hFile,
                       uint32_t dwFlags);
 uint32_t GetModuleFileName(int64_t hModule, char16_t *lpFilename,
                            uint32_t nSize);
+uint32_t GetModuleFileNameA(int64_t hModule, char *lpFilename, uint32_t nSize);
 intptr_t GetModuleHandle(const char *opt_lpModuleName);
 intptr_t GetModuleHandleW(const char16_t *opt_lpModuleName);
 void *GetProcAddress(int64_t hModule, const char *lpProcName);

libc/nt/files.h

@@ -199,6 +199,15 @@ bool32 WriteFileGather(int64_t hFileOpenedWithOverlappedAndNoBuffering,
                        uint32_t nNumberOfBytesToWrite, uint32_t *lpReserved,
                        struct NtOverlapped inout_lpOverlapped) paramsnonnull();
 
+#define kNtFileNameNormalized 0x0
+#define kNtVolumeNameDos      0x0
+#define kNtVolumeNameGuid     0x1
+#define kNtVolumeNameNt       0x2
+#define kNtVolumeNameNone     0x4
+#define kNtFileNameOpened     0x8
+uint32_t GetFinalPathNameByHandle(int64_t hFile, char16_t *out_path,
+                                  uint32_t size, uint32_t flags);
+
 #if ShouldUseMsabiAttribute()
 #include "libc/nt/thunk/files.inc"
 #endif /* ShouldUseMsabiAttribute() */

libc/nt/kernel32/GetFinalPathNameByHandleA.s

@@ -1,2 +1,12 @@
 .include "o/libc/nt/codegen.inc"
 .imp	kernel32,__imp_GetFinalPathNameByHandleA,GetFinalPathNameByHandleA,0
+
+	.text.windows
+GetFinalPathNameByHandleA:
+	push	%rbp
+	mov	%rsp,%rbp
+	.profilable
+	mov	__imp_GetFinalPathNameByHandleA(%rip),%rax
+	jmp	__sysv2nt
+	.endfn	GetFinalPathNameByHandleA,globl
+	.previous

libc/nt/kernel32/GetFinalPathNameByHandleW.s

@@ -1,2 +1,12 @@
 .include "o/libc/nt/codegen.inc"
 .imp	kernel32,__imp_GetFinalPathNameByHandleW,GetFinalPathNameByHandleW,0
+
+	.text.windows
+GetFinalPathNameByHandle:
+	push	%rbp
+	mov	%rsp,%rbp
+	.profilable
+	mov	__imp_GetFinalPathNameByHandleW(%rip),%rax
+	jmp	__sysv2nt
+	.endfn	GetFinalPathNameByHandle,globl
+	.previous

libc/nt/master.sh

@@ -2176,8 +2176,8 @@ imp	'GetFileVersionInfoSizeExA'				GetFileVersionInfoSizeExA				KernelBase	561
 imp	'GetFileVersionInfoSizeEx'				GetFileVersionInfoSizeExW				KernelBase	562
 imp	'GetFileVersionInfoSize'				GetFileVersionInfoSizeW					KernelBase	563
 imp	'GetFileVersionInfo'					GetFileVersionInfoW					KernelBase	564
-imp	'GetFinalPathNameByHandleA'				GetFinalPathNameByHandleA				kernel32	0		# KernelBase
+imp	'GetFinalPathNameByHandleA'				GetFinalPathNameByHandleA				kernel32	0	4	# KernelBase
-imp	'GetFinalPathNameByHandle'				GetFinalPathNameByHandleW				kernel32	0		# KernelBase
+imp	'GetFinalPathNameByHandle'				GetFinalPathNameByHandleW				kernel32	0	4	# KernelBase
 imp	'GetFirmwareEnvironmentVariableA'			GetFirmwareEnvironmentVariableA				kernel32	597
 imp	'GetFirmwareEnvironmentVariableExA'			GetFirmwareEnvironmentVariableExA			kernel32	598
 imp	'GetFirmwareEnvironmentVariableEx'			GetFirmwareEnvironmentVariableExW			kernel32	599

test/libc/calls/lseek_test.c

@@ -0,0 +1,55 @@
+/*-*- 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 2021 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/internal.h"
+#include "libc/fmt/fmt.h"
+#include "libc/log/check.h"
+#include "libc/runtime/runtime.h"
+#include "libc/sysv/consts/o.h"
+#include "libc/testlib/testlib.h"
+#include "libc/x/x.h"
+
+char testdir[PATH_MAX];
+
+void SetUp(void) {
+  sprintf(testdir, "o/tmp/%s.%d", program_invocation_short_name, getpid());
+  makedirs(testdir, 0755);
+  CHECK_NE(-1, chdir(testdir));
+}
+
+void TearDown(void) {
+  CHECK_NE(-1, chdir("../../.."));
+  CHECK_NE(-1, rmrf(testdir));
+}
+
+TEST(lseek, wat) {
+  int fd, pid;
+  char buf[8] = {0};
+  ASSERT_NE(-1, (fd = open("wut", O_RDWR | O_CREAT, 0644)));
+  ASSERT_EQ(3, write(fd, "wut", 3));
+  ASSERT_NE(-1, lseek(fd, 0, SEEK_SET));
+  if (!(pid = fork())) {
+    lseek(fd, 1, SEEK_SET);
+    _exit(0);
+  }
+  EXPECT_NE(-1, waitpid(pid, 0, 0));
+  EXPECT_EQ(1, read(fd, buf, 1));
+  EXPECT_EQ('u', buf[0]); /* wat?! */
+  EXPECT_NE(-1, close(fd));
+}