[PATCH] xmalloc: include size in the failure message

[Matthieu Moy <Matthieu.Moy@imag.fr>]

Out-of-memory errors can either be actual lack of memory, or bugs (like
code trying to call xmalloc(-1) by mistake). A little more information
may help tracking bugs reported by users.

Signed-off-by: Matthieu Moy <Matthieu.Moy@imag.fr>
---
Junio C Hamano <gitster@pobox.com> writes:

> Matthieu Moy <Matthieu.Moy@imag.fr> writes:
>
>> Out-of-memory errors can either be actual lack of memory, or bugs (like
>> code trying to call xmalloc(-1) by mistake). A little more information
>> may help tracking bugs reported by users.
>>
>> Signed-off-by: Matthieu Moy <Matthieu.Moy@imag.fr>
>> ---
>> This kind of thing may help for cases like
>>
>> Subject: Out of memory error during git push
>> http://thread.gmane.org/gmane.comp.version-control.git/153988
>
> Unless a single allocation try to grab unreasonably amount of memory,
> probably a failure from a specific single failure may not help much.

I don't promise miracle ;-). But at least, the diagnosis allows one to
distinguish small allocations, huge ones, and silly errors like small
negative numbers turned into unreasonably big ones.

>>  		if (!ret)
>> -			die("Out of memory, malloc failed");
>> +			die("Out of memory, malloc failed (tried to allocate %u bytes)", size);
>
> Perhaps use %lu format with cast to ulong?

Will do.

> alloc.c: fix formatting size_t to string
>
> Under NO_C99_FORMAT the format and the argument would not match if size_t
> is not the same size as uint.  As the one in sha1_file.c seems to be done
> in a better way, let's use that one.

Sounds good. Not sure why we don't basically use the %lu version
everywhere though.

 wrapper.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/wrapper.c b/wrapper.c
index afb4f6f..fd8ead3 100644
--- a/wrapper.c
+++ b/wrapper.c
@@ -40,7 +40,8 @@ void *xmalloc(size_t size)
 		if (!ret && !size)
 			ret = malloc(1);
 		if (!ret)
-			die("Out of memory, malloc failed");
+			die("Out of memory, malloc failed (tried to allocate %lu bytes)",
+			    (unsigned long)size);
 	}
 #ifdef XMALLOC_POISON
 	memset(ret, 0xA5, size);
-- 
1.7.2.1.83.ge0227