make failure on map creation returns -errno

This slightly improves error logging.

(also fd == 0 is not an error condition)

Test: atest, TreeHugger
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Change-Id: I135e7405c508951fba632c634bc4e2d2161fc940

1 files changed, 4 insertions, 2 deletions

diff --git a/libbpf_android/Loader.cpp b/libbpf_android/Loader.cpp
index 01f8964..e0d56e4 100644
--- a/libbpf_android/Loader.cpp
+++ b/libbpf_android/Loader.cpp
@@ -434,6 +434,7 @@ static int createMaps(const char* elfPath, ifstream& elfFile, vector<unique_fd>&
 
     for (int i = 0; i < (int)mapNames.size(); i++) {
         unique_fd fd;
+        int saved_errno;
         // Format of pin location is /sys/fs/bpf/<prefix>map_<filename>_<mapname>
         string mapPinLoc;
         bool reuse = false;
@@ -441,16 +442,17 @@ static int createMaps(const char* elfPath, ifstream& elfFile, vector<unique_fd>&
         mapPinLoc = string(BPF_FS_PATH) + prefix + "map_" + fname + "_" + string(mapNames[i]);
         if (access(mapPinLoc.c_str(), F_OK) == 0) {
             fd.reset(bpf_obj_get(mapPinLoc.c_str()));
+            saved_errno = errno;
             ALOGD("bpf_create_map reusing map %s, ret: %d\n", mapNames[i].c_str(), fd.get());
             reuse = true;
         } else {
             fd.reset(bpf_create_map(md[i].type, mapNames[i].c_str(), md[i].key_size, md[i].value_size,
                                     md[i].max_entries, md[i].map_flags));
+            saved_errno = errno;
             ALOGD("bpf_create_map name %s, ret: %d\n", mapNames[i].c_str(), fd.get());
         }
 
-        if (fd < 0) return fd;
-        if (fd == 0) return -EINVAL;
+        if (fd < 0) return -saved_errno;
 
         if (!reuse) {
             ret = bpf_obj_pin(fd, mapPinLoc.c_str());