From ea7f79f93796d68559a495be824b6bbd94dfe5f6 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Martin=20Storsj=C3=B6?= Date: Fri, 28 Feb 2014 12:19:49 +0200 Subject: [PATCH] qt-faststart: Avoid unintentionally sign extending BE_32 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Without this cast, the BE_32() expression is sign extended when assigned to an uint64_t, since the uint8_t|uint8_t expression is promoted to an int. Also avoid undefined behaviour when left shifting an uint8_t by 24 by casting it to an uint32_t explicitly before shifting. Based on a patch by Michael Niedermayer. Signed-off-by: Martin Storsjö --- tools/qt-faststart.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/tools/qt-faststart.c b/tools/qt-faststart.c index 792c272193..3a0139fecb 100644 --- a/tools/qt-faststart.c +++ b/tools/qt-faststart.c @@ -41,10 +41,10 @@ #define BE_16(x) ((((uint8_t*)(x))[0] << 8) | ((uint8_t*)(x))[1]) -#define BE_32(x) ((((uint8_t*)(x))[0] << 24) | \ - (((uint8_t*)(x))[1] << 16) | \ - (((uint8_t*)(x))[2] << 8) | \ - ((uint8_t*)(x))[3]) +#define BE_32(x) (((uint32_t)(((uint8_t*)(x))[0]) << 24) | \ + (((uint8_t*)(x))[1] << 16) | \ + (((uint8_t*)(x))[2] << 8) | \ + ((uint8_t*)(x))[3]) #define BE_64(x) (((uint64_t)(((uint8_t*)(x))[0]) << 56) | \ ((uint64_t)(((uint8_t*)(x))[1]) << 48) | \ @@ -123,7 +123,7 @@ int main(int argc, char *argv[]) if (fread(atom_bytes, ATOM_PREAMBLE_SIZE, 1, infile) != 1) { break; } - atom_size = (uint32_t) BE_32(&atom_bytes[0]); + atom_size = BE_32(&atom_bytes[0]); atom_type = BE_32(&atom_bytes[4]); /* keep ftyp atom */