[S] Change in flashrom[1.1.x]: linux_spi: Use fgets() to read buffer size

[Felix Singer (Code Review)]

Felix Singer has submitted this change. ( https://review.coreboot.org/c/flashrom/+/67848 )

Change subject: linux_spi: Use fgets() to read buffer size
......................................................................

linux_spi: Use fgets() to read buffer size

Since fread() returns the number of bytes read, this currently will only
check for errors if it returns 0 (i.e. the file was empty). However, it
is possible for fread() to encounter an error after reading a few bytes,
which this doesn't catch. Fix this by using fgets() instead, which will
return NULL if EOF or an error is encountered, and is simpler anyway.

Change-Id: I4f37c70e97149b87c6344e63a57d11ddde7638c4
Signed-off-by: Jacob Garber 
Found-by: Coverity CID 1403824
Reviewed-on: https://review.coreboot.org/c/flashrom/+/34848
Tested-by: build bot (Jenkins) 
Reviewed-by: David Hendricks 
Reviewed-on: https://review.coreboot.org/c/flashrom/+/67848
Reviewed-by: Felix Singer 
---
M linux_spi.c
1 file changed, 23 insertions(+), 2 deletions(-)

Approvals:
  build bot (Jenkins): Verified
  Felix Singer: Looks good to me, approved

diff --git a/linux_spi.c b/linux_spi.c
index 711ab4a..bcac8cb 100644
--- a/linux_spi.c
+++ b/linux_spi.c
@@ -138,8 +138,7 @@
    }

char buf[10];
-	memset(buf, 0, sizeof(buf));
-	if (!fread(buf, 1, sizeof(buf) - 1, fp)) {
+	if (!fgets(buf, sizeof(buf), fp)) {
    	if (feof(fp))
    		msg_pwarn("Cannot read %s: file is empty.\n", BUF_SIZE_FROM_SYSFS);
    	else