[PATCH 1/3] Btrfs-progs: move path modification to filters

[Lukas Czerner <lczerner@redhat.com>]

Commit 8e8e019e910f20947fea7eff5da40753639d8870 introduces -a option
which will list all subvolumes with distinguishing between relative and
absolute by prepending absolute patch with "<FS_TREE>".

This commit moves the path modification to a filter code rather than
doing so in path construction in resolve_root(). This gives us more
flexibility in formatting path output.

Signed-off-by: Lukas Czerner <lczerner@redhat.com>
---
 btrfs-list.c     |   32 +++++++++++++++++++++++---------
 btrfs-list.h     |    1 +
 cmds-subvolume.c |   11 +++++++++--
 man/btrfs.8.in   |    3 ++-
 4 files changed, 35 insertions(+), 12 deletions(-)

diff --git a/btrfs-list.c b/btrfs-list.c
index e5f0f96..77d99f8 100644
--- a/btrfs-list.c
+++ b/btrfs-list.c
@@ -628,15 +628,6 @@ static int resolve_root(struct root_lookup *rl, struct root_info *ri,
 		}
 
 		if (next == BTRFS_FS_TREE_OBJECTID) {
-			char p[] = "<FS_TREE>";
-			add_len = strlen(p);
-			len = strlen(full_path);
-			tmp = malloc(len + add_len + 2);
-			memcpy(tmp + add_len + 1, full_path, len);
-			tmp[add_len] = '/';
-			memcpy(tmp, p, add_len);
-			free(full_path);
-			full_path = tmp;
 			ri->top_id = next;
 			break;
 		}
@@ -1176,6 +1167,28 @@ static int filter_topid_equal(struct root_info *ri, u64 data)
 	return ri->top_id == data;
 }
 
+static int filter_full_path(struct root_info *ri, u64 data)
+{
+	if (ri->full_path && ri->top_id != data) {
+		char *tmp;
+		char p[] = "<FS_TREE>";
+		int add_len = strlen(p);
+		int len = strlen(ri->full_path);
+
+		tmp = malloc(len + add_len + 2);
+		if (!tmp) {
+			fprintf(stderr, "memory allocation failed\n");
+			exit(1);
+		}
+		memcpy(tmp + add_len + 1, ri->full_path, len);
+		tmp[add_len] = '/';
+		memcpy(tmp, p, add_len);
+		free(ri->full_path);
+		ri->full_path = tmp;
+	}
+	return 1;
+}
+
 static btrfs_list_filter_func all_filter_funcs[] = {
 	[BTRFS_LIST_FILTER_ROOTID]		= filter_by_rootid,
 	[BTRFS_LIST_FILTER_SNAPSHOT_ONLY]	= filter_snapshot,
@@ -1187,6 +1200,7 @@ static btrfs_list_filter_func all_filter_funcs[] = {
 	[BTRFS_LIST_FILTER_CGEN_LESS]		= filter_cgen_less,
 	[BTRFS_LIST_FILTER_CGEN_EQUAL]          = filter_cgen_equal,
 	[BTRFS_LIST_FILTER_TOPID_EQUAL]		= filter_topid_equal,
+	[BTRFS_LIST_FILTER_FULL_PATH]		= filter_full_path,
 };
 
 struct btrfs_list_filter_set *btrfs_list_alloc_filter_set(void)
diff --git a/btrfs-list.h b/btrfs-list.h
index cde4b3c..f7fbea6 100644
--- a/btrfs-list.h
+++ b/btrfs-list.h
@@ -71,6 +71,7 @@ enum btrfs_list_filter_enum {
 	BTRFS_LIST_FILTER_CGEN_LESS,
 	BTRFS_LIST_FILTER_CGEN_MORE,
 	BTRFS_LIST_FILTER_TOPID_EQUAL,
+	BTRFS_LIST_FILTER_FULL_PATH,
 	BTRFS_LIST_FILTER_MAX,
 };
 
diff --git a/cmds-subvolume.c b/cmds-subvolume.c
index ac39f7b..37cb8cc 100644
--- a/cmds-subvolume.c
+++ b/cmds-subvolume.c
@@ -277,7 +277,9 @@ static const char * const cmd_subvol_list_usage[] = {
 	"List subvolumes (and snapshots)",
 	"",
 	"-p           print parent ID",
-	"-a           print all the subvolumes in the filesystem.",
+	"-a           print all the subvolumes in the filesystem and",
+	"             distinguish absolute and relative path with respect",
+	"             to the given <path>",
 	"-u           print the uuid of subvolumes (and snapshots)",
 	"-t           print the result as a table",
 	"-s           list snapshots only in the filesystem",
@@ -400,7 +402,12 @@ static int cmd_subvol_list(int argc, char **argv)
 	}
 
 	top_id = btrfs_list_get_path_rootid(fd);
-	if (!is_list_all)
+
+	if (is_list_all)
+		btrfs_list_setup_filter(&filter_set,
+					BTRFS_LIST_FILTER_FULL_PATH,
+					top_id);
+	else
 		btrfs_list_setup_filter(&filter_set,
 					BTRFS_LIST_FILTER_TOPID_EQUAL,
 					top_id);
diff --git a/man/btrfs.8.in b/man/btrfs.8.in
index 9222580..d6d8e94 100644
--- a/man/btrfs.8.in
+++ b/man/btrfs.8.in
@@ -124,7 +124,8 @@ and top level. The parent's ID may be used at mount time via the
 
 \fB-t\fP print the result as a table.
 
-\fB-a\fP print all the subvolumes in the filesystem.
+\fB-a\fP print all the subvolumes in the filesystem and distinguish between
+absolute and relative path with respect to the given <path>.
 
 \fB-r\fP only readonly subvolumes in the filesystem wille be listed.
 
-- 
1.7.7.6