restore: Parse /proc/self/maps for self mappings

On restore we only need to know currnet task mappings' start and end
to find where to put the restorer blob. And since the smaps file in
/proc/pid is up to 3 times slower, than the maps one, it makes
perfect sense just to parse the latter one.
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

cr-restore.c

@@ -2231,7 +2231,7 @@ static int sigreturn_restore(pid_t pid, CoreEntry *core)
 	 * this unwanted mapping might get overlapped by the restorer.
 	 */
 
-	ret = parse_smaps(pid, &self_vmas, false);
+	ret = parse_self_maps_lite(&self_vmas);
 	close_proc();
 	if (ret < 0)
 		goto err;

include/proc_parse.h

@@ -142,6 +142,7 @@ extern struct mount_info *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 vm_area_list *vma_area_list, bool use_map_files);
+extern int parse_self_maps_lite(struct vm_area_list *vms);
 extern int parse_pid_status(pid_t pid, struct proc_status_creds *);
 
 union fdinfo_entries {

proc_parse.c

@@ -212,6 +212,40 @@ static int vma_get_mapfile(struct vma_area *vma, DIR *mfd,
 	return 0;
 }
 
+int parse_self_maps_lite(struct vm_area_list *vms)
+{
+	FILE *maps;
+
+	vm_area_list_init(vms);
+
+	maps = fopen("/proc/self/maps", "r");
+	if (maps == NULL) {
+		pr_perror("Can't open self maps");
+		return -1;
+	}
+
+	while (fgets(buf, BUF_SIZE, maps) != NULL) {
+		struct vma_area *vma;
+		char *end;
+
+		vma = alloc_vma_area();
+		if (!vma) {
+			fclose(maps);
+			return -1;
+		}
+
+		vma->e->start = strtoul(buf, &end, 16);
+		vma->e->end = strtoul(end + 1, NULL, 16);
+		list_add_tail(&vma->list, &vms->h);
+		vms->nr++;
+
+		pr_debug("Parsed %lx-%lx vma\n", vma->e->start, vma->e->end);
+	}
+
+	fclose(maps);
+	return 0;
+}
+
 int parse_smaps(pid_t pid, struct vm_area_list *vma_area_list, bool use_map_files)
 {
 	struct vma_area *vma_area = NULL;