[PATCH weston v4 1/5] Standardize error checking for strtol calls

[Bryce Harrington]

This tightens up the strtol() error checking in several places where it
is used for parsing environment variables, and in the backlight
interface that is reading numbers from files under /sys/class/backlight.
All of these uses are expecting strings containing decimal numbers and
nothing else, so the error checking can all be tightened up and made
consistent with other strtol() calls.

This follows the error checking style used in Wayland
(c.f. wayland-client.c and scanner.c) and c.f. commit cbc05378.

Signed-off-by: Bryce Harrington <bryce at osg.samsung.com>
Reviewed-by: Eric Engestrom <eric.engestrom at imgtec.com>
---
 compositor/main.c           |  3 ++-
 compositor/systemd-notify.c |  2 +-
 libweston/compositor.c      |  3 ++-
 libweston/libbacklight.c    | 10 +++++++++-
 4 files changed, 14 insertions(+), 4 deletions(-)

diff --git a/compositor/main.c b/compositor/main.c
index 99cb868..0f7a0c0 100644
--- a/compositor/main.c
+++ b/compositor/main.c
@@ -1685,8 +1685,9 @@ int main(int argc, char *argv[])
 	server_socket = getenv("WAYLAND_SERVER_SOCKET");
 	if (server_socket) {
 		weston_log("Running with single client\n");
+		errno = 0;
 		fd = strtol(server_socket, &end, 10);
-		if (*end != '\0')
+		if (errno != 0 || end == server_socket || *end != '\0')
 			fd = -1;
 	} else {
 		fd = -1;
diff --git a/compositor/systemd-notify.c b/compositor/systemd-notify.c
index 9fbd5ee..6104124 100644
--- a/compositor/systemd-notify.c
+++ b/compositor/systemd-notify.c
@@ -146,7 +146,7 @@ module_init(struct weston_compositor *compositor,
 
 	errno = 0;
 	watchdog_time_conv = strtol(watchdog_time_env, &tail, 10);
-	if ((errno != 0) || (*tail != '\0'))
+	if (errno != 0 || tail == watchdog_time_env || *tail != '\0')
 		return 0;
 
 	/* Convert 'WATCHDOG_USEC' to milliseconds and notify
diff --git a/libweston/compositor.c b/libweston/compositor.c
index b045381..e9c2a83 100644
--- a/libweston/compositor.c
+++ b/libweston/compositor.c
@@ -4628,8 +4628,9 @@ weston_environment_get_fd(const char *env)
 	e = getenv(env);
 	if (!e)
 		return -1;
+	errno = 0;
 	fd = strtol(e, &end, 10);
-	if (*end != '\0')
+	if (errno != 0 || end == e || *end != '\0')
 		return -1;
 
 	flags = fcntl(fd, F_GETFD);
diff --git a/libweston/libbacklight.c b/libweston/libbacklight.c
index 4039575..59f4e44 100644
--- a/libweston/libbacklight.c
+++ b/libweston/libbacklight.c
@@ -48,6 +48,7 @@ static long backlight_get(struct backlight *backlight, char *node)
 {
 	char buffer[100];
 	char *path;
+	char *end;
 	int fd;
 	long value, ret;
 
@@ -65,8 +66,15 @@ static long backlight_get(struct backlight *backlight, char *node)
 		goto out;
 	}
 
-	value = strtol(buffer, NULL, 10);
+	errno = 0;
+	value = strtol(buffer, &end, 10);
+	if (errno != 0 || end == buffer || *end != '\0') {
+		ret = -1;
+		goto out;
+	}
+
 	ret = value;
+
 out:
 	if (fd >= 0)
 		close(fd);
-- 
1.9.1