anon: Factor out checking for anon inode link types

Funny, but kernel reports some of them with []-s and some (well,
ok, inotofy only) without...
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

eventfd.c

@@ -29,20 +29,7 @@ struct eventfd_file_info {
 /* Checks if file desciptor @lfd is eventfd */
 int is_eventfd_link(int lfd)
 {
-	char link[PATH_MAX], path[32];
-	ssize_t ret;
-
-	snprintf(path, sizeof(path), "/proc/self/fd/%d", lfd);
-	ret = readlink(path, link, sizeof(link));
-	if (ret < 0) {
-		pr_perror("Can't read link of fd %d\n", lfd);
-		return 0;
-	}
-	link[ret] = 0;
-	if (!strcmp(link, "anon_inode:[eventfd]"))
-		return 1;
-
-	return 0;
+	return is_anon_link_type(lfd, "[eventfd]");
 }
 
 static void pr_info_eventfd(char *action, struct eventfd_file_entry *efe)

eventpoll.c

@@ -36,20 +36,7 @@ static LIST_HEAD(eventpoll_tfds);
 /* Checks if file desciptor @lfd is eventfd */
 int is_eventpoll_link(int lfd)
 {
-	char link[PATH_MAX], path[32];
-	ssize_t ret;
-
-	snprintf(path, sizeof(path), "/proc/self/fd/%d", lfd);
-	ret = readlink(path, link, sizeof(link));
-	if (ret < 0) {
-		pr_perror("Can't read link of fd %d\n", lfd);
-		return 0;
-	}
-	link[ret] = 0;
-	if (!strcmp(link, "anon_inode:[eventpoll]"))
-		return 1;
-
-	return 0;
+	return is_anon_link_type(lfd, "[eventpoll]");
 }
 
 static void pr_info_eventpoll_tfd(char *action, struct eventpoll_tfd_entry *e)

include/util.h

@@ -279,5 +279,6 @@ static inline dev_t kdev_to_odev(u32 kdev)
 
 int copy_file(int fd_in, int fd_out, size_t bytes);
 bool is_anon_inode(struct statfs *statfs);
+int is_anon_link_type(int lfd, char *type);
 
 #endif /* UTIL_H_ */

inotify.c

@@ -52,20 +52,7 @@ static char fdinfo_buf[PAGE_SIZE];
 /* Checks if file desciptor @lfd is inotify */
 int is_inotify_link(int lfd)
 {
-	char link[PATH_MAX], path[32];
-	ssize_t ret;
-
-	snprintf(path, sizeof(path), "/proc/self/fd/%d", lfd);
-	ret = readlink(path, link, sizeof(link));
-	if (ret < 0) {
-		pr_perror("Can't read link of fd %d\n", lfd);
-		return 0;
-	}
-	link[ret] = 0;
-	if (!strcmp(link, "anon_inode:inotify"))
-		return 1;
-
-	return 0;
+	return is_anon_link_type(lfd, "inotify");
 }
 
 void show_inotify_wd(int fd_inotify_wd, struct cr_options *o)

util.c

@@ -310,3 +310,19 @@ bool is_anon_inode(struct statfs *statfs)
 {
 	return statfs->f_type == ANON_INODE_FS_MAGIC;
 }
+
+int is_anon_link_type(int lfd, char *type)
+{
+	char link[PATH_MAX], aux[32];
+	ssize_t ret;
+
+	snprintf(aux, sizeof(aux), "/proc/self/fd/%d", lfd);
+	ret = readlink(aux, link, sizeof(link));
+	if (ret < 0) {
+		pr_perror("Can't read link of fd %d\n", lfd);
+		return 0;
+	}
+	link[ret] = 0;
+	snprintf(aux, sizeof(aux), "anon_inode:%s", type);
+	return !strcmp(link, aux);
+}