Add compressBound_z and deflateBound_z functions for large values.

These take and return size_t integers, instead of unsigned longs,
for those platforms with 32-bit longs. This commit also assures
that overflows of either integer type results in the maximum value
for that type, instead of wrapping to small values.

1 files changed, 7 insertions, 2 deletions

diff --git a/compress.c b/compress.c
index f43bacf7..0c709d06 100644
--- a/compress.c
+++ b/compress.c
@@ -69,7 +69,12 @@ int ZEXPORT compress(Bytef *dest, uLongf *destLen, const Bytef *source,
      If the default memLevel or windowBits for deflateInit() is changed, then
    this function needs to be updated.
  */
+z_size_t ZEXPORT compressBound_z(z_size_t sourceLen) {
+    z_size_t bound = sourceLen + (sourceLen >> 12) + (sourceLen >> 14) +
+                     (sourceLen >> 25) + 13;
+    return bound < sourceLen ? (z_size_t)-1 : bound;
+}
 uLong ZEXPORT compressBound(uLong sourceLen) {
-    return sourceLen + (sourceLen >> 12) + (sourceLen >> 14) +
-           (sourceLen >> 25) + 13;
+    z_size_t bound = compressBound_z(sourceLen);
+    return (uLong)bound != bound ? (uLong)-1 : (uLong)bound;
 }