apds990x_proxy: fix errno usage.

This patch fixes one of the most common errors about errno usage:

if (somecall() == -1) {
    printf("somecall() failed\n");
    if (errno == ...) { ... }
}

printf may change the value of errno, so that the errno value in
the if statement is not anymore referring to 'somecall()'
function.

The correct usage should be:

if (somecall() == -1) {
    int errsv = errno;
    printf("somecall() failed\n");
    if (errsv == ...) { ... }
}

Signed-off-by: Andi Shyti <andi.shyti@nokia.com>

1 files changed, 9 insertions, 4 deletions

diff --git a/drivers/misc/apds990x_proxy.c b/drivers/misc/apds990x_proxy.c
index f5e701c..ba6ea3d 100644
--- a/drivers/misc/apds990x_proxy.c
+++ b/drivers/misc/apds990x_proxy.c
@@ -47,25 +47,30 @@ int write_file(char *fname, const char *val)
 {
 	int fd;
 	ssize_t ret;
+	int retval = 0;
 
 	fd = open(fname, O_WRONLY);
 	if (fd < 0) {
+		retval = errno;
 		fprintf(stderr, "%s: %s\n", fname, strerror(errno));
-		return errno;
+		return retval;
 	}
 
 	ret = write(fd, val, 1);
 	if (ret != 1) {
+		retval = errno;
 		fprintf(stderr, "%s: %s\n", fname, strerror(errno));
 		close(fd);
-		return errno;
+		return retval;
 	}
 
 	fd = close(fd);
-	if (fd < 0)
+	if (fd < 0) {
+		retval = errno;
 		fprintf(stderr, "%s: %s\n", fname, strerror(errno));
+	}
 
-	return errno;
+	return retval;
 }
 
 int read_proxy(void)