1 files changed, 32 insertions, 14 deletions

diff --git a/src/ext4_resize.c b/src/ext4_resize.c
index 39e16529..78b66432 100644
--- a/src/ext4_resize.c
+++ b/src/ext4_resize.c
@@ -10,6 +10,7 @@
 #include <unistd.h>
 #include <stdint.h>
 #include <stdlib.h>
+#include <string.h>
 #include <sys/ioctl.h>
 #include <sys/mount.h>
 
@@ -19,33 +20,50 @@ typedef unsigned long long __u64;
 #define EXT4_IOC_RESIZE_FS		_IOW('f', 16, __u64)
 #endif
 
+#define pr_error(fmt, ...) do { \
+	fprintf (stderr, "ext4_resize.c: " fmt, ##__VA_ARGS__); \
+} while (0)
+
+static void usage(void)
+{
+	fprintf(stdout, "\nUsage: ext4_resize [mnt_path] [new_size(blocks)]\n");
+}
+
 int main(int argc, char **argv)
 {
 	__u64	new_size;
 	int	error, fd;
-	char	*tmp = NULL;
+	char	*mnt_dir = NULL, *tmp = NULL;
 
 	if (argc != 3) {
-		fputs("insufficient arguments\n", stderr);
-		return 1;
-	}
-	fd = open(argv[1], O_RDONLY);
-	if (!fd) {
-		perror(argv[1]);
-		return 1;
+		error = EINVAL;
+		pr_error("insufficient arguments\n");
+		usage();
+		return error;
 	}
 
+	mnt_dir = argv[1];
+
 	errno = 0;
 	new_size = strtoull(argv[2], &tmp, 10);
 	if ((errno) || (*tmp != '\0')) {
-		fprintf(stderr, "%s: invalid new size\n", argv[0]);
-		return 1;
+		error = errno;
+		pr_error("invalid new size\n");
+		return error;
+	}
+
+	fd = open(mnt_dir, O_RDONLY);
+	if (fd < 0) {
+		error = errno;
+		pr_error("open() failed with error: %s\n", strerror(error));
+		return error;
 	}
 
-	error = ioctl(fd, EXT4_IOC_RESIZE_FS, &new_size);
-	if (error < 0) {
-		perror("EXT4_IOC_RESIZE_FS");
-		return 1;
+	if(ioctl(fd, EXT4_IOC_RESIZE_FS, &new_size) < 0) {
+		error = errno;
+		pr_error("EXT4_IOC_RESIZE_FS ioctl() failed with error: %s\n", strerror(error));
+		return error;
 	}
+
 	return 0;
 }