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[v3,04/22] reftable/basics: handle allocation failures in `reftable_calloc()`

Message ID f6ad92ffd01c442dacd3ac6aa448891028636636.1727680272.git.ps@pks.im (mailing list archive)
State Accepted
Commit 6593e147d3992eb52cb53b6f8a09dc3e10f79613
Headers show
Series refatble: handle allocation errors | expand

Commit Message

Patrick Steinhardt Sept. 30, 2024, 8:08 a.m. UTC 
Handle allocation failures in `reftable_calloc()`.

While at it, remove our use of `st_mult()` that would cause us to die on
an overflow. From the caller's point of view there is not much of a
difference between arguments that are too large to be multiplied and a
request that is too big to handle by the allocator: in both cases the
allocation cannot be fulfilled. And in neither of these cases do we want
the reftable library to die.

While we could use `unsigned_mult_overflows()` to handle the overflow
gracefully, we instead open-code it to further our goal of converting
the reftable codebase to become a standalone library that can be reused
by external projects.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
---
 reftable/basics.c | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)
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Patch

diff --git a/reftable/basics.c b/reftable/basics.c
index 4adc98cf5d..3350bbffa2 100644
--- a/reftable/basics.c
+++ b/reftable/basics.c
@@ -37,9 +37,16 @@  void reftable_free(void *p)
 
 void *reftable_calloc(size_t nelem, size_t elsize)
 {
-	size_t sz = st_mult(nelem, elsize);
-	void *p = reftable_malloc(sz);
-	memset(p, 0, sz);
+	void *p;
+
+	if (nelem && elsize > SIZE_MAX / nelem)
+		return NULL;
+
+	p = reftable_malloc(nelem * elsize);
+	if (!p)
+		return NULL;
+
+	memset(p, 0, nelem * elsize);
 	return p;
 }