Cross platform low level file IO wrappers

util/file/file_io.cc

Index: util/file/file_io.cc
diff --git a/util/file/fd_io.cc b/util/file/file_io.cc
similarity index 40%
copy from util/file/fd_io.cc
copy to util/file/file_io.cc
index cc97400ba34ba3e827a71f9c9dc1955ad18e1e8d..c1eceeb4e2cdff4bf1a300b04a8e5342a4d54daf 100644
--- a/util/file/fd_io.cc
+++ b/util/file/file_io.cc
@@ -12,71 +12,16 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-#include "util/file/fd_io.h"
-
-#include <unistd.h>
+#include "util/file/file_io.h"
 
 #include "base/logging.h"
 #include "base/numerics/safe_conversions.h"
-#include "base/posix/eintr_wrapper.h"
-
-namespace {
-
-struct ReadTraits {
-  using VoidBufferType = void*;
-  using CharBufferType = char*;
-  static ssize_t Operate(int fd, CharBufferType buffer, size_t size) {
-    return read(fd, buffer, size);
-  }
-};
-
-struct WriteTraits {
-  using VoidBufferType = const void*;
-  using CharBufferType = const char*;
-  static ssize_t Operate(int fd, CharBufferType buffer, size_t size) {
-    return write(fd, buffer, size);
-  }
-};
-
-template <typename Traits>
-ssize_t ReadOrWrite(int fd,
-                    typename Traits::VoidBufferType buffer,
-                    size_t size) {
-  typename Traits::CharBufferType buffer_c =
-      reinterpret_cast<typename Traits::CharBufferType>(buffer);
-
-  ssize_t total_bytes = 0;
-  while (size > 0) {
-    ssize_t bytes = HANDLE_EINTR(Traits::Operate(fd, buffer_c, size));
-    if (bytes < 0) {
-      return bytes;
-    } else if (bytes == 0) {
-      break;
-    }
-
-    buffer_c += bytes;
-    size -= bytes;
-    total_bytes += bytes;
-  }
-
-  return total_bytes;
-}
-
-}  // namespace
 
 namespace crashpad {
 
-ssize_t ReadFD(int fd, void* buffer, size_t size) {
-  return ReadOrWrite<ReadTraits>(fd, buffer, size);
-}
-
-ssize_t WriteFD(int fd, const void* buffer, size_t size) {
-  return ReadOrWrite<WriteTraits>(fd, buffer, size);
-}
-
-bool LoggingReadFD(int fd, void* buffer, size_t size) {
+bool LoggingReadFile(FileHandle fh, void* buffer, size_t size) {

[Mark Mentovai, 2014/12/16 22:40:25]

Throughout this file: the header declared the parameter name as file, not fh.
The implementation and declaration should match.

I like “file” better. Fewer uncommon abbreviations.

[Mark Mentovai, 2014/12/16 22:40:25]

I’m really glad that all of these wrappers are shareable!

[scottmg, 2014/12/17 00:22:58]

Done.

   ssize_t expect = base::checked_cast<ssize_t>(size);
-  ssize_t rv = ReadFD(fd, buffer, size);
+  ssize_t rv = ReadFile(fh, buffer, size);
   if (rv < 0) {
     PLOG(ERROR) << "read";
     return false;
@@ -89,9 +34,9 @@ bool LoggingReadFD(int fd, void* buffer, size_t size) {
   return true;
 }
 
-bool LoggingWriteFD(int fd, const void* buffer, size_t size) {
+bool LoggingWriteFile(FileHandle fh, const void* buffer, size_t size) {
   ssize_t expect = base::checked_cast<ssize_t>(size);
-  ssize_t rv = WriteFD(fd, buffer, size);
+  ssize_t rv = WriteFile(fh, buffer, size);
   if (rv < 0) {
     PLOG(ERROR) << "write";
     return false;
@@ -104,17 +49,17 @@ bool LoggingWriteFD(int fd, const void* buffer, size_t size) {
   return true;
 }
 
-void CheckedReadFD(int fd, void* buffer, size_t size) {
-  CHECK(LoggingReadFD(fd, buffer, size));
+void CheckedReadFile(FileHandle fh, void* buffer, size_t size) {
+  CHECK(LoggingReadFile(fh, buffer, size));
 }
 
-void CheckedWriteFD(int fd, const void* buffer, size_t size) {
-  CHECK(LoggingWriteFD(fd, buffer, size));
+void CheckedWriteFile(FileHandle fh, const void* buffer, size_t size) {
+  CHECK(LoggingWriteFile(fh, buffer, size));
 }
 
-void CheckedReadFDAtEOF(int fd) {
+void CheckedReadFileAtEOF(FileHandle fh) {

[Mark Mentovai, 2014/12/16 22:40:25]

Especially now that we’ve got multiple implementations, this can probably
benefit from a test to make sure that things like this function have the same
semantics.

It’s OK to skip that in this change, but one of us should circle back and add a
test afterwards.

[scottmg, 2014/12/17 00:22:58]

Agreed. I'll skip for now and add once I can actually test on Windows.

   char c;
-  ssize_t rv = ReadFD(fd, &c, 1);
+  ssize_t rv = ReadFile(fh, &c, 1);
   if (rv < 0) {
     PCHECK(rv == 0) << "read";
   } else {
@@ -122,14 +67,8 @@ void CheckedReadFDAtEOF(int fd) {
   }
 }
 
-bool LoggingCloseFD(int fd) {
-  int rv = IGNORE_EINTR(close(fd));
-  PLOG_IF(ERROR, rv != 0) << "close";
-  return rv == 0;
-}
-
-void CheckedCloseFD(int fd) {
-  CHECK(LoggingCloseFD(fd));
+void CheckedCloseFile(FileHandle fh) {
+  CHECK(LoggingCloseFile(fh));
 }
 
 }  // namespace crashpad