proc: Sanitize mountinfo parsing

Make the proc_mountinfo obtaned after parse form a single linked list.
That's much easier to handle and doesn't have an artificial limitation
of 64 items...
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

include/proc_parse.h

@@ -91,9 +91,10 @@ struct proc_mountinfo {
 	unsigned int	s_dev;
 	char		root[64];
 	char		mountpoint[64];
+	struct proc_mountinfo *next;
 };
 
-extern int parse_mountinfo(pid_t pid, struct proc_mountinfo *mi, int nr_elems);
+extern struct proc_mountinfo *parse_mountinfo(pid_t pid);
 extern int parse_pid_stat(pid_t pid, struct proc_pid_stat *s);
 extern int parse_pid_stat_small(pid_t pid, struct proc_pid_stat_small *s);
 extern int parse_smaps(pid_t pid, struct list_head *vma_area_list, bool use_map_files);

mount.c

@@ -15,38 +15,22 @@
 #include "proc_parse.h"
 
 static struct proc_mountinfo *mntinfo;
-static int nr_mntinfo;
 
 int open_mount(unsigned int s_dev)
 {
-	static int last = 0;
-	int i;
+	struct proc_mountinfo *i;
 
-again:
-	for (i = last; i < nr_mntinfo; i++) {
-		if (s_dev == mntinfo[i].s_dev) {
-			last = i;
-			return open(mntinfo[i].mountpoint, O_RDONLY);
-		}
-	}
-
-	if (last) {
-		last = 0;
-		goto again;
-	}
+	for (i = mntinfo; i != NULL; i = i->next)
+		if (s_dev == i->s_dev)
+			return open(i->mountpoint, O_RDONLY);
 
 	return -ENOENT;
 }
 
 int collect_mount_info(void)
 {
-	nr_mntinfo = 64;
-	mntinfo = xmalloc(sizeof(*mntinfo) * nr_mntinfo);
-	if (!mntinfo)
-		return -1;
-
-	nr_mntinfo = parse_mountinfo(getpid(), mntinfo, nr_mntinfo);
-	if (nr_mntinfo < 1) {
+	mntinfo = parse_mountinfo(getpid());
+	if (!mntinfo) {
 		pr_err("Parsing mountinfo %d failed\n", getpid());
 		return -1;
 	}

proc_parse.c

@@ -470,44 +470,49 @@ err_parse:
 	return 0;
 }
 
-int parse_mountinfo(pid_t pid, struct proc_mountinfo *mi, int nr_elems)
+struct proc_mountinfo *parse_mountinfo(pid_t pid)
 {
-	FILE *f = NULL;
+	struct proc_mountinfo *list = NULL;
+	FILE *f;
 	char str[256];
-	int i = 0;
 
 	snprintf(str, sizeof(str), "/proc/%d/mountinfo", pid);
 	f = fopen(str, "r");
 	if (!f) {
 		pr_perror("Can't open %d mountinfo", pid);
-		return -1;
+		return NULL;
 	}
 
 	while (fgets(str, sizeof(str), f)) {
-		unsigned int kmaj, kmin, parent_mnt_id;
+		struct proc_mountinfo *new;
+		unsigned int kmaj, kmin;
 		int ret;
 
-		if ((i + 1) >= nr_elems) {
-			i = -ENOMEM;
-			goto out_close;
-		}
+		new = xmalloc(sizeof(*new));
+		if (!new)
+			goto err;
 
 		ret = sscanf(str, "%i %i %u:%u %63s %63s",
-			     &mi[i].mnt_id, &parent_mnt_id,
-			     &kmaj, &kmin, mi[i].root,
-			     mi[i].mountpoint);
+			     &new->mnt_id, &new->parent_mnt_id,
+			     &kmaj, &kmin, new->root, new->mountpoint);
 		if (ret != 6) {
 			pr_err("Bad format in %d mountinfo\n", pid);
-			i = -1;
-			goto out_close;
+			goto err;
 		}
 
-		mi[i].s_dev = MKKDEV(kmaj, kmin);
-		i++;
+		new->s_dev = MKKDEV(kmaj, kmin);
+		new->next = list;
+		list = new;
 	}
-
-out_close:
-	fclose(f);
 out:
-	return i;
+	fclose(f);
+	return list;
+
+err:
+	while (list) {
+		struct proc_mountinfo *next = list->next;
+		xfree(list);
+		list = next;
+	}
+	goto out;
 }