Bazel client: do not use `errno`.

Do not use `errno` in platform-independent code,
because Windows API functions don't set it.

This change abstracts away error handling and the
functions whose `errno` result we care about, will
set an input error variable.

Fixes https://github.com/bazelbuild/bazel/issues/2506

--
PiperOrigin-RevId: 148977873
MOS_MIGRATED_REVID=148977873

1 files changed, 13 insertions, 5 deletions

diff --git a/src/main/cpp/util/file.cc b/src/main/cpp/util/file.cc
index 44df52be12..cd9d9076d1 100644
--- a/src/main/cpp/util/file.cc
+++ b/src/main/cpp/util/file.cc
@@ -11,7 +11,6 @@
 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 // See the License for the specific language governing permissions and
 // limitations under the License.
-#include <errno.h>
 #include <limits.h>  // PATH_MAX
 
 #include <algorithm>
@@ -34,12 +33,17 @@ bool ReadFrom(file_handle_type handle, string *content, int max_size) {
   content->clear();
   char buf[kReadSize];
   // OPT:  This loop generates one spurious read on regular files.
+  int error;
   while (int r = ReadFromHandle(
              handle, buf,
              max_size > 0 ? std::min(static_cast<size_t>(max_size), kReadSize)
-                          : kReadSize)) {
+                          : kReadSize,
+             &error)) {
     if (r < 0) {
-      if (errno == EINTR || errno == EAGAIN) continue;
+      if (error == ReadFileResult::INTERRUPTED ||
+          error == ReadFileResult::AGAIN) {
+        continue;
+      }
       return false;
     }
     content->append(buf, r);
@@ -57,10 +61,14 @@ bool ReadFrom(file_handle_type handle, string *content, int max_size) {
 bool ReadFrom(file_handle_type handle, void *data, size_t size) {
   static const size_t kReadSize = 4096;  // read 4K chunks
   size_t offset = 0;
+  int error;
   while (int r = ReadFromHandle(handle, reinterpret_cast<char *>(data) + offset,
-                                std::min(kReadSize, size))) {
+                                std::min(kReadSize, size), &error)) {
     if (r < 0) {
-      if (errno == EINTR || errno == EAGAIN) continue;
+      if (error == ReadFileResult::INTERRUPTED ||
+          error == ReadFileResult::AGAIN) {
+        continue;
+      }
       return false;
     }
     offset += r;