Bazel client, Windows: fix ReadFile("/dev/null")

Mimic read(2) behavior when reading from /dev/null
and always successfully read 0 bytes.

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

--
PiperOrigin-RevId: 149286494
MOS_MIGRATED_REVID=149286494

1 files changed, 9 insertions, 0 deletions

diff --git a/src/main/cpp/util/file_windows.cc b/src/main/cpp/util/file_windows.cc
index 35d824223e..145d5dae0c 100644
--- a/src/main/cpp/util/file_windows.cc
+++ b/src/main/cpp/util/file_windows.cc
@@ -599,6 +599,11 @@ int ReadFromHandle(file_handle_type handle, void* data, size_t size,
 }
 
 bool ReadFile(const string& filename, string* content, int max_size) {
+  if (IsDevNull(filename)) {
+    // mimic read(2) behavior: we can always read 0 bytes from /dev/null
+    content->clear();
+    return true;
+  }
   HANDLE handle;
   if (!OpenFileForReading(filename, &handle)) {
     return false;
@@ -613,6 +618,10 @@ bool ReadFile(const string& filename, string* content, int max_size) {
 }
 
 bool ReadFile(const string& filename, void* data, size_t size) {
+  if (IsDevNull(filename)) {
+    // mimic read(2) behavior: we can always read 0 bytes from /dev/null
+    return true;
+  }
   HANDLE handle;
   if (!OpenFileForReading(filename, &handle)) {
     return false;