Issue 42001: Breakpad Linux Dumper: remove compilation warnings in guid_creator.cc.

Building on Ubuntu 9.10 with the distributed compiler (GCC 4.4.1), we get
warnings like the following:

guid_creator.cc:56: warning: dereferencing type-punned pointer will break strict-aliasing rules

It doesn't matter in this case, but there's no crying need to use
reinterpret casts in an endian-dependent way when there are plenty of
well-defined ways to get the same effect.

a=jimblandy, r=nealsid


git-svn-id: http://google-breakpad.googlecode.com/svn/trunk@447 4c0a9323-5329-0410-9bdc-e9ce6186880e

1 files changed, 18 insertions, 4 deletions

diff --git a/src/common/linux/guid_creator.cc b/src/common/linux/guid_creator.cc
index d133c6b0..7611cc3e 100644
--- a/src/common/linux/guid_creator.cc
+++ b/src/common/linux/guid_creator.cc
@@ -49,12 +49,26 @@ class GUIDGenerator {
     srandom(time(NULL));
   }
 
+  static u_int32_t BytesToUInt32(const u_int8_t bytes[]) {
+    return ((u_int32_t) bytes[0]
+            | ((u_int32_t) bytes[1] << 8)
+            | ((u_int32_t) bytes[2] << 16)
+            | ((u_int32_t) bytes[3] << 24));
+  }
+
+  static void UInt32ToBytes(u_int8_t bytes[], u_int32_t n) {
+    bytes[0] = n & 0xff;
+    bytes[1] = (n >> 8) & 0xff;
+    bytes[2] = (n >> 16) & 0xff;
+    bytes[3] = (n >> 24) & 0xff;
+  }
+
   bool CreateGUID(GUID *guid) const {
     guid->data1 = random();
     guid->data2 = (u_int16_t)(random());
     guid->data3 = (u_int16_t)(random());
-    *reinterpret_cast<u_int32_t*>(&guid->data4[0]) = random();
-    *reinterpret_cast<u_int32_t*>(&guid->data4[4]) = random();
+    UInt32ToBytes(&guid->data4[0], random());
+    UInt32ToBytes(&guid->data4[4], random());
     return true;
   }
 };
@@ -72,8 +86,8 @@ bool GUIDToString(const GUID *guid, char *buf, int buf_len) {
   assert(buf_len > kGUIDStringLength);
   int num = snprintf(buf, buf_len, kGUIDFormatString,
                      guid->data1, guid->data2, guid->data3,
-                     *reinterpret_cast<const u_int32_t *>(&(guid->data4[0])),
-                     *reinterpret_cast<const u_int32_t *>(&(guid->data4[4])));
+                     GUIDGenerator::BytesToUInt32(&(guid->data4[0])),
+                     GUIDGenerator::BytesToUInt32(&(guid->data4[4])));
   if (num != kGUIDStringLength)
     return false;