From: Mathias Kresin <dev@kresin.me>
Date: Sat, 5 Jan 2019 06:40:55 +0000 (+0100)
Subject: firmware-utils: mkdlinkfw: fix error handling
X-Git-Tag: v19.07.0-rc1~1597
X-Git-Url: http://git.openwrt.org/?p=openwrt%2Fopenwrt.git;a=commitdiff_plain;h=0e78af22d95d91f7c2fdfc66fac993c6c5d349d8

firmware-utils: mkdlinkfw: fix error handling

fread() doesn't set errno, ferror need to be used to check for errors.
While at it, check if we read the expect number of elements.

Signed-off-by: Mathias Kresin <dev@kresin.me>
---

diff --git a/tools/firmware-utils/src/mkdlinkfw-lib.c b/tools/firmware-utils/src/mkdlinkfw-lib.c
index 3b71fda7db..b3f3f41348 100644
--- a/tools/firmware-utils/src/mkdlinkfw-lib.c
+++ b/tools/firmware-utils/src/mkdlinkfw-lib.c
@@ -97,6 +97,7 @@ int read_to_buf(const struct file_info *fdata, char *buf)
 {
 	FILE *f;
 	int ret = EXIT_FAILURE;
+	size_t read;
 
 	f = fopen(fdata->file_name, "r");
 	if (f == NULL) {
@@ -104,9 +105,8 @@ int read_to_buf(const struct file_info *fdata, char *buf)
 		goto out;
 	}
 
-	errno = 0;
-	fread(buf, fdata->file_size, 1, f);
-	if (errno != 0) {
+	read = fread(buf, fdata->file_size, 1, f);
+	if (ferror(f) || read != 1) {
 		ERRS("unable to read from file \"%s\"", fdata->file_name);
 		goto out_close;
 	}