Merge branch 'maint-0.3.1'

changes/diagnose_22752

@@ -0,0 +1,4 @@
+  o Minor features (bug mitigation, diagnostics, logging):
+    - Avoid an assertion failure, and log a better error message,
+      when unable to remove a file from the consensus cache on
+      Windows. Attempts to mitigate and diagnose bug 22752.

src/common/storagedir.c

@@ -119,7 +119,8 @@ storage_dir_clean_tmpfiles(storage_dir_t *d)
     char *path = NULL;
     tor_asprintf(&path, "%s/%s", d->directory, fname);
     if (unlink(sandbox_intern_string(path))) {
-      log_warn(LD_FS, "Unable to unlink %s", escaped(path));
+      log_warn(LD_FS, "Unable to unlink %s while cleaning "
+               "temporary files: %s", escaped(path), strerror(errno));
       tor_free(path);
       continue;
     }
@@ -455,7 +456,8 @@ storage_dir_remove_file(storage_dir_t *d,
   if (unlink(ipath) == 0) {
     storage_dir_reduce_usage(d, size);
   } else {
-    log_warn(LD_FS, "Unable to unlink %s", escaped(path));
+    log_warn(LD_FS, "Unable to unlink %s while removing file: %s",
+             escaped(path), strerror(errno));
     tor_free(path);
     return;
   }

src/or/consdiffmgr.c

@@ -325,7 +325,8 @@ cdm_diff_ht_purge(consensus_flavor_t flav,
     if ((*diff)->cdm_diff_status == CDM_DIFF_PRESENT &&
         flav == (*diff)->flavor) {
 
-      if (consensus_cache_entry_handle_get((*diff)->entry) == NULL) {
+      if (BUG((*diff)->entry == NULL) ||
+          consensus_cache_entry_handle_get((*diff)->entry) == NULL) {
         /* the underlying entry has gone away; drop this. */
         next = HT_NEXT_RMV(cdm_diff_ht, &cdm_diff_ht, diff);
         cdm_diff_free(this);
@@ -622,6 +623,9 @@ consdiffmgr_find_diff_from(consensus_cache_entry_t **entry_out,
     return CONSDIFF_IN_PROGRESS;
   }
 
+  if (BUG(ent->entry == NULL)) {
+    return CONSDIFF_NOT_FOUND;
+  }
   *entry_out = consensus_cache_entry_handle_get(ent->entry);
   return (*entry_out) ? CONSDIFF_AVAILABLE : CONSDIFF_NOT_FOUND;