From patchwork Mon Aug 1 06:49:59 2011 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Subject: Check fread() results to avoid gcc 4.6 warnings Date: Sun, 31 Jul 2011 20:49:59 -0000 From: David Gibson X-Patchwork-Id: 107682 Message-Id: <1312181399-29841-1-git-send-email-david@gibson.dropbear.id.au> To: qemu-devel@nongnu.org Cc: qemu-trivial@nongnu.org When compiling with gcc 4.6, some code in fw_cfg.c complains that fop_ret is assigned but not used (which is true). However, it looks like the meaningless assignments to fop_ret were done to suppress other gcc warnings due to the fact that fread() is labelled as warn_unused_result in glibc. This patch avoids both errors, by actually checking the fread() result code and dropping out with an error message if it fails. Signed-off-by: David Gibson Reviewed-by: Stefan Hajnoczi Tested-by: Stefan Berger --- hw/fw_cfg.c | 13 +++++++++++++ 1 files changed, 13 insertions(+), 0 deletions(-) diff --git a/hw/fw_cfg.c b/hw/fw_cfg.c index a29db90..e4847b7 100644 --- a/hw/fw_cfg.c +++ b/hw/fw_cfg.c @@ -87,6 +87,13 @@ static FILE *probe_splashfile(char *filename, int *file_sizep, int *file_typep) /* check magic ID */ fseek(fp, 0L, SEEK_SET); fop_ret = fread(buf, 1, 2, fp); + if (fop_ret != 2) { + error_report("Could not read header from '%s': %s", + filename, strerror(errno)); + fclose(fp); + fp = NULL; + return fp; + } filehead_value = (buf[0] + (buf[1] << 8)) & 0xffff; if (filehead_value == 0xd8ff) { file_type = JPG_FILE; @@ -181,6 +188,12 @@ static void fw_cfg_bootsplash(FWCfgState *s) boot_splash_filedata_size = file_size; fseek(fp, 0L, SEEK_SET); fop_ret = fread(boot_splash_filedata, 1, file_size, fp); + if (fop_ret != file_size) { + error_report("failed to read data from '%s'.", + boot_splash_filename); + fclose(fp); + return; + } fclose(fp); /* insert data */ if (file_type == JPG_FILE) {