From: Steinar H. Gunderson <sgunderson@bigfoot.com>
Date: Sun, 18 Aug 2013 00:48:13 +0000 (+0200)
Subject: Use memcpy instead of incurring potential unaligned reads when reading the Metacube... 
X-Git-Tag: 1.0.0~8
X-Git-Url: https://git.sesse.net/?p=cubemap;a=commitdiff_plain;h=22cd7233eabd1d012f29e890ec67c6b70a0d6753

Use memcpy instead of incurring potential unaligned reads when reading the Metacube header.

This would probably be a portability problem for many other platforms than x86.
---

diff --git a/httpinput.cpp b/httpinput.cpp
index 80daa1a..c923145 100644
--- a/httpinput.cpp
+++ b/httpinput.cpp
@@ -535,16 +535,17 @@ void HTTPInput::process_data(char *ptr, size_t bytes)
 		}
 
 		// Now it's safe to read the header.
-		metacube2_block_header *hdr = reinterpret_cast<metacube2_block_header *>(pending_data.data());	
-		assert(memcmp(hdr->sync, METACUBE2_SYNC, sizeof(hdr->sync)) == 0);
-		uint32_t size = ntohl(hdr->size);
-		uint16_t flags = ntohs(hdr->flags);
-		uint16_t expected_csum = metacube2_compute_crc(hdr);
-
-		if (expected_csum != ntohs(hdr->csum)) {
+		metacube2_block_header hdr;
+		memcpy(&hdr, pending_data.data(), sizeof(hdr));
+		assert(memcmp(hdr.sync, METACUBE2_SYNC, sizeof(hdr.sync)) == 0);
+		uint32_t size = ntohl(hdr.size);
+		uint16_t flags = ntohs(hdr.flags);
+		uint16_t expected_csum = metacube2_compute_crc(&hdr);
+
+		if (expected_csum != ntohs(hdr.csum)) {
 			log(WARNING, "[%s] Metacube checksum failed (expected 0x%x, got 0x%x), "
 				"not reading block claiming to be %d bytes (flags=%x).",
-				url.c_str(), expected_csum, ntohs(hdr->csum),
+				url.c_str(), expected_csum, ntohs(hdr.csum),
 				size, flags);
 
 			// Drop only the first byte, and let the rest of the code handle resync.