Similar to testing expectations about malloc with GIT_ALLOC_LIMIT (see
commit d41489 and previous commit), it can be useful to test
expectations about mmap.
This introduces a new environment variable GIT_MMAP_LIMIT to limit the
largest allowed mmap length. xmmap() is modified to check the limit.
Together with GIT_ALLOC_LIMIT tests can now easily confirm expectations
about memory consumption.
GIT_MMAP_LIMIT will be used in the next commit to test that data will be
streamed to an external filter without mmaping the entire file.
[commit d41489]: d41489a6424308dc9a0409bc2f6845aa08bd4f7d Add more large
blob test cases
Signed-off-by: Steffen Prohaska <prohaska@xxxxxx>
---
sha1_file.c | 21 ++++++++++++++++++++-
1 file changed, 20 insertions(+), 1 deletion(-)
diff --git a/sha1_file.c b/sha1_file.c
index 00c07f2..3204f66 100644
--- a/sha1_file.c
+++ b/sha1_file.c
@@ -663,10 +663,29 @@ void release_pack_memory(size_t need)
; /* nothing */
}
+static void mmap_limit_check(size_t length)
+{
+ static size_t limit = SIZE_MAX;
+ if (limit == SIZE_MAX) {
+ const char *var = "GIT_MMAP_LIMIT";
+ unsigned long val = 0;
+ const char *env = getenv(var);
+ if (env && !git_parse_ulong(env, &val))
+ die("Failed to parse %s", var);
+ limit = val;
+ }
+ if (limit && length > limit)
+ die("attempting to mmap %"PRIuMAX" over limit %"PRIuMAX,
+ (uintmax_t)length, (uintmax_t)limit);
+}
+
void *xmmap(void *start, size_t length,
int prot, int flags, int fd, off_t offset)
{
- void *ret = mmap(start, length, prot, flags, fd, offset);
+ void *ret;
+
+ mmap_limit_check(length);
+ ret = mmap(start, length, prot, flags, fd, offset);
if (ret == MAP_FAILED) {
if (!length)
return NULL;
--
2.1.0.8.gd3b6067
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