[PATCH bpf-next 2/3] libbpf: cleanup after partial failure in bpf_object__pin

[Stanislav Fomichev]

bpftool will use bpf_object__pin in the next commit to pin all programs
and maps from the file; in case of a partial failure, we need to get
back to the clean state (undo previous program/map pins).

Signed-off-by: Stanislav Fomichev <s...@google.com>
---
 tools/lib/bpf/libbpf.c | 58 ++++++++++++++++++++++++++++++++++--------
 1 file changed, 48 insertions(+), 10 deletions(-)

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index d6e62e90e8d4..309abe7196f3 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -1803,14 +1803,17 @@ int bpf_object__pin(struct bpf_object *obj, const char 
*path)
 
                len = snprintf(buf, PATH_MAX, "%s/%s", path,
                               bpf_map__name(map));
-               if (len < 0)
-                       return -EINVAL;
-               else if (len >= PATH_MAX)
-                       return -ENAMETOOLONG;
+               if (len < 0) {
+                       err = -EINVAL;
+                       goto err_unpin_maps;
+               } else if (len >= PATH_MAX) {
+                       err = -ENAMETOOLONG;
+                       goto err_unpin_maps;
+               }
 
                err = bpf_map__pin(map, buf);
                if (err)
-                       return err;
+                       goto err_unpin_maps;
        }
 
        bpf_object__for_each_program(prog, obj) {
@@ -1819,17 +1822,52 @@ int bpf_object__pin(struct bpf_object *obj, const char 
*path)
 
                len = snprintf(buf, PATH_MAX, "%s/%s", path,
                               prog->section_name);
-               if (len < 0)
-                       return -EINVAL;
-               else if (len >= PATH_MAX)
-                       return -ENAMETOOLONG;
+               if (len < 0) {
+                       err = -EINVAL;
+                       goto err_unpin_programs;
+               } else if (len >= PATH_MAX) {
+                       err = -ENAMETOOLONG;
+                       goto err_unpin_programs;
+               }
 
                err = bpf_program__pin(prog, buf);
                if (err)
-                       return err;
+                       goto err_unpin_programs;
        }
 
        return 0;
+
+err_unpin_programs:
+       bpf_object__for_each_program(prog, obj) {
+               char buf[PATH_MAX];
+               int len;
+
+               len = snprintf(buf, PATH_MAX, "%s/%s", path,
+                              prog->section_name);
+               if (len < 0)
+                       continue;
+               else if (len >= PATH_MAX)
+                       continue;
+
+               unlink(buf);
+       }
+
+err_unpin_maps:
+       bpf_map__for_each(map, obj) {
+               char buf[PATH_MAX];
+               int len;
+
+               len = snprintf(buf, PATH_MAX, "%s/%s", path,
+                              bpf_map__name(map));
+               if (len < 0)
+                       continue;
+               else if (len >= PATH_MAX)
+                       continue;
+
+               unlink(buf);
+       }
+
+       return err;
 }
 
 void bpf_object__close(struct bpf_object *obj)
-- 
2.19.1.930.g4563a0d9d0-goog