[PATCH] commit-slab: sizeof() the right type in xrealloc

When allocating the slab, the code accidentally computed the array size from s->slab (an elemtype**). The slab is an array of elemtype*, however, so we should take the size of *s->slab.

Noticed-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Thomas Rast <tr@thomasrast.ch>
---
[I hope this comes through clean.  git-send-email is currently broken
for me, and I'm still investigating, so I have to kludge around it.]

I browsed around for a while, and couldn't find out whether any architecture actually has any hope of running git (i.e. is at least mostly POSIX conformant) but still violates the assumption that all pointers[*] are the same size.

The comp.lang.c FAQ has some interesting examples of wildly different pointer representations at:

  http://c-faq.com/null/machexamp.html

Consider the cases mentioned there where void* and char* have different representations from, e.g., int*. Then if elemtype is char, the slab will be too small before this patch.

But I have no idea if any of those are POSIXish.

One interesting, though orthogonal, tidbit is that POSIX actually requires _function_ pointers to have the same representation as void*. From the specification of dlsym(), which depends on this to be able to return function pointers:

RATIONALE
  [...] Indeed, the ISO C standard does not require that an object of
  type void * can hold a pointer to a function. Implementations
  supporting the XSI extension, however, do require that an object of
  type void * can hold a pointer to a function.

Thank god for POSIX.  So much craziness averted.

[*] Note that C++ method pointers are yet another story. This only applies to the kinds of pointers that C supports.

 commit-slab.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)