comments

Author: romkatv

src/dir.cc

@@ -116,16 +116,18 @@ bool ListDir(int dir_fd, Arena& arena, std::vector<char*>& entries, bool precomp
       entries.clear();
       return false;
     }
-    if (n == 0) break;
     for (int pos = 0; pos < n;) {
       auto* ent = reinterpret_cast<linux_dirent64*>(buf + pos);
       if (!Dots(ent->d_name)) entries.push_back(ent->d_name);
       pos += ent->d_reclen;
-      // It's tempting to bail here if n + sizeof(linux_dirent64) + 512 <= n. After all, there
-      // was enough space for another entry but SYS_getdents64 didn't write it, so this must be
-      // the end of the directory listing, right? Unfortuatenly, no. SYS_getdents64 is finicky.
-      // It sometimes writes a partial list of entries even if the full list would fit.
     }
+    if (n == 0) break;
+    // The following optimization relies on SYS_getdents64 always returning as many
+    // entries as would fit. This is not guaranteed by the specification and I don't
+    // know if this is true in practice. The optimization has no measurable effect on
+    // gitstatus performance, so it's turned off.
+    //
+    //   if (n + sizeof(linux_dirent64) + 512 <= kBufSize) break;
   }
 
   if (case_sensitive) {