From 42f8f9346ce9752d02a99a9ce545866da672ecaf Mon Sep 17 00:00:00 2001
From: skal <pascal.massimino@gmail.com>
Date: Tue, 22 Jan 2013 10:34:35 +0100
Subject: [PATCH] handle malloc(0) and calloc(0) uniformly on all platforms

also change lossless encoder logic, which was relying on explicit
NULL return from WebPSafeMalloc(0)

renamed function to CheckSizeArgumentsOverflow() explicitly

addresses issue #138

Change-Id: Ibbd51cc0281e60e86dfd4c5496274399e4c0f7f3
---
 src/enc/vp8l.c             |  8 ++++++--
 src/utils/huffman_encode.c |  4 ++++
 src/utils/utils.c          | 11 ++++++-----
 3 files changed, 16 insertions(+), 7 deletions(-)

diff --git a/src/enc/vp8l.c b/src/enc/vp8l.c
index bd73e56a..56131b9c 100644
--- a/src/enc/vp8l.c
+++ b/src/enc/vp8l.c
@@ -221,7 +221,7 @@ static int GetHuffBitLengthsAndCodes(
   }
 
   // Create Huffman trees.
-  for (i = 0; i < histogram_image_size; ++i) {
+  for (i = 0; ok && (i < histogram_image_size); ++i) {
     HuffmanTreeCode* const codes = &huffman_codes[5 * i];
     VP8LHistogram* const histo = histogram_image->histograms[i];
     ok = ok && VP8LCreateHuffmanTree(histo->literal_, 15, codes + 0);
@@ -232,7 +232,11 @@ static int GetHuffBitLengthsAndCodes(
   }
 
  End:
-  if (!ok) free(mem_buf);
+  if (!ok) {
+    free(mem_buf);
+    // If one VP8LCreateHuffmanTree() above fails, we need to clean up behind.
+    memset(huffman_codes, 0, 5 * histogram_image_size * sizeof(*huffman_codes));
+  }
   return ok;
 }
 
diff --git a/src/utils/huffman_encode.c b/src/utils/huffman_encode.c
index e8cbc628..2d680e3e 100644
--- a/src/utils/huffman_encode.c
+++ b/src/utils/huffman_encode.c
@@ -188,6 +188,10 @@ static int GenerateOptimalTree(const int* const histogram, int histogram_size,
     }
   }
 
+  if (tree_size_orig == 0) {   // pretty optimal already!
+    return 1;
+  }
+
   // 3 * tree_size is enough to cover all the nodes representing a
   // population and all the inserted nodes combining two existing nodes.
   // The tree pool needs 2 * (tree_size_orig - 1) entities, and the
diff --git a/src/utils/utils.c b/src/utils/utils.c
index 673b7e28..555f9a33 100644
--- a/src/utils/utils.c
+++ b/src/utils/utils.c
@@ -19,7 +19,8 @@ extern "C" {
 //------------------------------------------------------------------------------
 // Checked memory allocation
 
-static int CheckSizeArguments(uint64_t nmemb, size_t size) {
+// Returns 0 in case of overflow of nmemb * size.
+static int CheckSizeArgumentsOverflow(uint64_t nmemb, size_t size) {
   const uint64_t total_size = nmemb * size;
   if (nmemb == 0) return 1;
   if ((uint64_t)size > WEBP_MAX_ALLOCABLE_MEMORY / nmemb) return 0;
@@ -28,13 +29,13 @@ static int CheckSizeArguments(uint64_t nmemb, size_t size) {
 }
 
 void* WebPSafeMalloc(uint64_t nmemb, size_t size) {
-  if (!CheckSizeArguments(nmemb, size)) return NULL;
-  return malloc((size_t)(nmemb * size));
+  if (!CheckSizeArgumentsOverflow(nmemb, size)) return NULL;
+  return (nmemb > 0 && size > 0) ? malloc((size_t)(nmemb * size)) : NULL;
 }
 
 void* WebPSafeCalloc(uint64_t nmemb, size_t size) {
-  if (!CheckSizeArguments(nmemb, size)) return NULL;
-  return calloc((size_t)nmemb, size);
+  if (!CheckSizeArgumentsOverflow(nmemb, size)) return NULL;
+  return (nmemb > 0 && size > 0) ? calloc((size_t)nmemb, size) : NULL;
 }
 
 //------------------------------------------------------------------------------