reftable/basics: ban standard allocator functions

The reftable library uses pluggable allocators, which means that we
shouldn't ever use the standard allocator functions. But it is an easy
mistake to make to accidentally use e.g. free(3P) instead of the
reftable-specific `reftable_free()` function, and we do not have any
mechanism to detect this misuse right now.

Introduce a couple of macros that ban the standard allocators, similar
to how we do it in "banned.h".

Note that we do not ban the following two classes of functions:

  - Macros like `FREE_AND_NULL()` or `REALLOC_ARRAY()`. As those expand
    to code that contains already-banned functions we'd get a compiler
    error even without banning those macros explicitly.

  - Git-specific allocators like `xmalloc()` and friends. The primary
    reason is that there are simply too many of them, so we're rather
    aiming for best effort here. Furthermore, the eventual goal is to
    make them unavailable in the reftable library place by not pulling
    them in via "git-compat-utils.h" anymore.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/reftable/basics.c b/reftable/basics.c
index ea53cf102ad529b96055b273f3ac725c349ac846..c8396dc5253d68105e5cee34639358306457be63 100644 (file)
--- a/reftable/basics.c
+++ b/reftable/basics.c
@@ -6,6 +6,7 @@ license that can be found in the LICENSE file or at
 https://developers.google.com/open-source/licenses/bsd
 */
 
+#define REFTABLE_ALLOW_BANNED_ALLOCATORS
 #include "basics.h"
 #include "reftable-basics.h"
 

diff --git a/reftable/basics.h b/reftable/basics.h
index 7f0f20e50c7715032255424f3280394377c6829f..4c9ef0fe6c5f18e6ec371c2263e03d4af171e7d5 100644 (file)
--- a/reftable/basics.h
+++ b/reftable/basics.h
@@ -73,6 +73,20 @@ char *reftable_strdup(const char *str);
        } while (0)
 #define REFTABLE_FREE_AND_NULL(p) do { reftable_free(p); (p) = NULL; } while (0)
 
+#ifndef REFTABLE_ALLOW_BANNED_ALLOCATORS
+# define REFTABLE_BANNED(func) use_reftable_##func##_instead
+# undef malloc
+# define malloc(sz) REFTABLE_BANNED(malloc)
+# undef realloc
+# define realloc(ptr, sz) REFTABLE_BANNED(realloc)
+# undef free
+# define free(ptr) REFTABLE_BANNED(free)
+# undef calloc
+# define calloc(nelem, elsize) REFTABLE_BANNED(calloc)
+# undef strdup
+# define strdup(str) REFTABLE_BANNED(strdup)
+#endif
+
 /* Find the longest shared prefix size of `a` and `b` */
 struct strbuf;
 int common_prefix_size(struct strbuf *a, struct strbuf *b);