Bazel client, Windows: implement WriteFile

See https://github.com/bazelbuild/bazel/issues/2107

--
PiperOrigin-RevId: 144218095
MOS_MIGRATED_REVID=144218095

2 files changed, 30 insertions, 12 deletions

diff --git a/src/main/cpp/util/file_posix.cc b/src/main/cpp/util/file_posix.cc
index cc8cadbcf0..02c0fa8055 100644
--- a/src/main/cpp/util/file_posix.cc
+++ b/src/main/cpp/util/file_posix.cc
@@ -189,7 +189,6 @@ bool ReadFile(const string &filename, string *content, int max_size) {
   close(fd);
   return result;
 }
-#endif  // not __CYGWIN__
 
 bool WriteFile(const void *data, size_t size, const string &filename) {
   UnlinkPath(filename);  // We don't care about the success of this.
@@ -209,11 +208,6 @@ bool WriteFile(const void *data, size_t size, const string &filename) {
   return result;
 }
 
-// TODO(bazel-team): implement all functions in file_windows.cc, use them from
-// MSYS, remove file_posix.cc from the `srcs` of
-// //src/main/cpp/util:file when building for MSYS, and remove all
-// #ifndef __CYGWIN__ directives.
-#ifndef __CYGWIN__
 bool UnlinkPath(const string &file_path) {
   return unlink(file_path.c_str()) == 0;
 }
diff --git a/src/main/cpp/util/file_windows.cc b/src/main/cpp/util/file_windows.cc
index 63d6d66efb..d213b64179 100644
--- a/src/main/cpp/util/file_windows.cc
+++ b/src/main/cpp/util/file_windows.cc
@@ -406,14 +406,38 @@ bool ReadFile(const string& filename, string* content, int max_size) {
   return result;
 }
 
-#ifdef COMPILER_MSVC
 bool WriteFile(const void* data, size_t size, const string& filename) {
-  // TODO(bazel-team): implement this.
-  pdie(255, "blaze_util::WriteFile is not implemented on Windows");
-  return false;
+  if (IsDevNull(filename)) {
+    return true;  // mimic write(2) behavior with /dev/null
+  }
+  wstring wpath;
+  if (!AsWindowsPathWithUncPrefix(filename, &wpath)) {
+    return false;
+  }
+
+  UnlinkPathW(wpath);  // We don't care about the success of this.
+  HANDLE handle = CreateFileW(
+      /* lpFileName */ wpath.c_str(),
+      /* dwDesiredAccess */ GENERIC_WRITE,
+      /* dwShareMode */ FILE_SHARE_READ,
+      /* lpSecurityAttributes */ NULL,
+      /* dwCreationDisposition */ CREATE_ALWAYS,
+      /* dwFlagsAndAttributes */ FILE_ATTRIBUTE_NORMAL,
+      /* hTemplateFile */ NULL);
+  if (handle == INVALID_HANDLE_VALUE) {
+    return false;
+  }
+
+  bool result = WriteTo(
+      [handle](const void* buf, size_t bufsize) {
+        DWORD actually_written = 0;
+        ::WriteFile(handle, buf, bufsize, &actually_written, NULL);
+        return actually_written;
+      },
+      data, size);
+  CloseHandle(handle);
+  return result;
 }
-#else  // not COMPILER_MSVC
-#endif  // COMPILER_MSVC
 
 static bool UnlinkPathW(const wstring& path) {
   DWORD attrs = ::GetFileAttributesW(path.c_str());