Am 01.12.2016 um 21:22 schrieb Junio C Hamano:
Junio C Hamano <gitster@xxxxxxxxx> writes:
Eh, wait. BSD and Microsoft have paramters reordered in the
callback comparison function. I suspect that would not fly very
well.
Hmm. We could do it like this, which may not be too bad.
It's kinda cool to have a bespoke compatibility layer for major
platforms, but the more I think about it the less I can answer why we
would want that. Safety, reliability and performance can't be good
reasons -- if our fallback function lacks in these regards then we have
to improve it in any case.
Text size could be a valid reason, but the full function only adds a bit
more than 2KB to the unstripped git binary.
The flip side is we'd build an ifdef maze that's harder to read and a
lot more difficult to test.
What do we get in return for that additional complexity?
#if APPLE_QSORT_R
struct apple_qsort_adapter {
int (*user_cmp)(const void *, const void *, void *);
void *user_ctx;
}
static int apple_qsort_adapter_cmp(void *ctx, const void *a, const void *b)
{
struct apple_qsort_adapter *wrapper_ctx = ctx;
return wrapper_ctx->user_cmp(a, b, wrapper_ctx->user_ctx);
}
#endif
int git_qsort_s(void *b, size_t n, size_t s,
int (*cmp)(const void *, const void *, void *), void *ctx)
{
if (!n)
return 0;
if (!b || !cmp)
return -1;
#if GNU_QSORT_R
qsort_r(b, n, s, cmp, ctx);
#elif APPLE_QSORT_R
{
struct appple_qsort_adapter a = { cmp, ctx };
qsort_r(b, n, s, &a, appple_qsort_adapter_cmp);
}
#endif
Nit: The fallback for non-GNU, non-Apple systems is missing here, but
the idea is illustrated clearly enough.
return 0;
}