[PATCH 7/8] wrapper: expose try_to_free_pack_memory()

As v1.7.0-rc0~43 (slim down "git show-index", 2010-01-21) explains,
xmalloc() is dependent on zlib, the sha1 lib, and the rest of git's
object file access machinery via try_to_free_pack_memory.  That is
overkill when xmalloc() is only being used to print a message and exit
on memory exhaustion.

So let each caller decide whether the "discard pack windows" logic is
needed.  Programs using the sha1_file library should request that
xmalloc discard stale windows when an allocation fails, by calling

	set_try_to_free_handler(try_to_free_pack_memory);

A later patch will stop setting up that handler except in response to
such explicit requests, allowing wrapper.o to be used without adding a
sha1_file.o dependency by programs that do not access the object db.

Signed-off-by: Jonathan Nieder <redacted>
---
 git-compat-util.h |    1 +
 sha1_file.c       |    5 +++++
 wrapper.c         |    7 +------
 3 files changed, 7 insertions(+), 6 deletions(-)

diff --git a/git-compat-util.h b/git-compat-util.h
index 029162e..07ee75e 100644
--- a/git-compat-util.h
+++ b/git-compat-util.h

@@ -387,6 +387,7 @@ static inline void *gitmempcpy(void *dest, const void *src, size_t n)
 #endif
 
 extern void release_pack_memory(size_t, int);
+extern void try_to_free_pack_memory(size_t size);
 
 typedef void (*try_to_free_t)(size_t);
 extern try_to_free_t set_try_to_free_routine(try_to_free_t);

diff --git a/sha1_file.c b/sha1_file.c
index 8e299ae..c48baaa 100644
--- a/sha1_file.c
+++ b/sha1_file.c

@@ -576,6 +576,11 @@ void release_pack_memory(size_t need, int fd)
 		; /* nothing */
 }
 
+void try_to_free_pack_memory(size_t size)
+{
+	release_pack_memory(size, -1);
+}
+
 void *xmmap(void *start, size_t length,
 	int prot, int flags, int fd, off_t offset)
 {

diff --git a/wrapper.c b/wrapper.c
index 185dfbc..6c6579b 100644
--- a/wrapper.c
+++ b/wrapper.c

@@ -3,12 +3,7 @@
  */
 #include "cache.h"
 
-static void try_to_free_builtin(size_t size)
-{
-	release_pack_memory(size, -1);
-}
-
-static void (*try_to_free_routine)(size_t size) = try_to_free_builtin;
+static void (*try_to_free_routine)(size_t size) = try_to_free_pack_memory;
 
 try_to_free_t set_try_to_free_routine(try_to_free_t routine)
 {

-- 
1.7.2.3.557.gab647.dirty