[PATCH 6/9] Mdmonitor: Refactor write_autorebuild_pid()

[Mateusz Grzonka <mateusz.grzonka@xxxxxxxxx>]

Add better error handling and check for symlinks when opening MDMON_DIR.

Signed-off-by: Mateusz Grzonka <mateusz.grzonka@xxxxxxxxx>
---
 Monitor.c | 55 ++++++++++++++++++++++++++++++++++++-------------------
 1 file changed, 36 insertions(+), 19 deletions(-)

diff --git a/Monitor.c b/Monitor.c
index 80e43ebe..3e09f2a2 100644
--- a/Monitor.c
+++ b/Monitor.c
@@ -33,6 +33,7 @@
 #endif
 
 #define EVENT_NAME_MAX 32
+#define AUTOREBUILD_PID_PATH MDMON_DIR "/autorebuild.pid"
 
 struct state {
 	char *devname;
@@ -123,7 +124,7 @@ static int check_udev_activity(void);
 static void link_containers_with_subarrays(struct state *list);
 static int make_daemon(char *pidfile);
 static void try_spare_migration(struct state *statelist);
-static void write_autorebuild_pid(void);
+static int write_autorebuild_pid(void);
 
 int Monitor(struct mddev_dev *devlist,
 	    char *mailaddr, char *alert_cmd,
@@ -224,7 +225,8 @@ int Monitor(struct mddev_dev *devlist,
 	}
 
 	if (share)
-		write_autorebuild_pid();
+		if (write_autorebuild_pid() != 0)
+			return 1;
 
 	if (devlist == NULL) {
 		mdlist = conf_get_ident(NULL);
@@ -428,29 +430,44 @@ static int check_one_sharer(int scan)
 	return 0;
 }
 
-static void write_autorebuild_pid()
+/**
+ * write_autorebuild_pid() - Writes pid to autorebuild.pid file.
+ *
+ * Return: 0 on success, 1 on error
+ */
+static int write_autorebuild_pid(void)
 {
-	char path[PATH_MAX];
-	int pid;
-	FILE *fp = NULL;
-	sprintf(path, "%s/autorebuild.pid", MDMON_DIR);
+	FILE *fp;
+	int fd;
 
 	if (mkdir(MDMON_DIR, 0700) < 0 && errno != EEXIST) {
-		pr_err("Can't create autorebuild.pid file\n");
-	} else {
-		int fd = open(path, O_WRONLY | O_CREAT | O_TRUNC, 0700);
+		pr_err("%s: %s\n", strerror(errno), MDMON_DIR);
+		return 1;
+	}
 
-		if (fd >= 0)
-			fp = fdopen(fd, "w");
+	if (!is_directory(MDMON_DIR)) {
+		pr_err("%s is not a regular directory.\n", MDMON_DIR);
+		return 1;
+	}
 
-		if (!fp)
-			pr_err("Can't create autorebuild.pid file\n");
-		else {
-			pid = getpid();
-			fprintf(fp, "%d\n", pid);
-			fclose(fp);
-		}
+	fd = open(AUTOREBUILD_PID_PATH, O_WRONLY | O_CREAT | O_TRUNC, 0700);
+
+	if (fd < 0) {
+		pr_err("Error opening %s file.\n", AUTOREBUILD_PID_PATH);
+		return 1;
 	}
+
+	fp = fdopen(fd, "w");
+
+	if (!fp) {
+		pr_err("Error opening fd for %s file.\n", AUTOREBUILD_PID_PATH);
+		return 1;
+	}
+
+	fprintf(fp, "%d\n", getpid());
+
+	fclose(fp);
+	return 0;
 }
 
 #define BASE_MESSAGE "%s event detected on md device %s"
-- 
2.26.2