Question

I want to use the git’s malloc and realloc wrappers in my code for OOM(out of memory) conditions. Here is its code:

void *xmalloc(size_t size)
{
      void *ret = malloc(size);
      if (!ret && !size)
              ret = malloc(1);
      if (!ret) {
              release_pack_memory(size, -1);
              ret = malloc(size);
              if (!ret && !size)
                      ret = malloc(1);
              if (!ret)
                      die("Out of memory, malloc failed");
      }
#ifdef XMALLOC_POISON
      memset(ret, 0xA5, size);
#endif
      return ret;
}

but the release_pack_memory function is in sha1_file.c header file and this function have references to the functions in other header files in Git’s code and I didn’t want to put so much effort for isolate this function from Git’s codebase. At the moment I am looking for an alternative function for release_pack_memory function, or can you recommend me another alternative. I’ll be thankful for any kind of help

Answer 1

Why do you want to use Git’s malloc wrapper? Do you understand what it’s doing? If so, why do you think you need a “replacement” for release_pack_memory?

All this wrapper does* is, if malloc fails, it tries to free up some memory that it uses for caches (which is what release_pack_memory does) and then tries again. If you don’t have any in-memory caches then there’s really no point copying this wrapper (and if you do have in-memory caches, then you should already know how to free memory from it without having to copy this function).

* It also contains a check for if size is 0 on platforms that do not support malloc(0), if this is a concern to you, then the release_pack_memory stuff is still useless.