From: Aki Tuomi <aki.tuomi@open-xchange.com>
Date: Thu, 15 Aug 2024 18:14:06 +0000 (+0300)
Subject: lib: mempool - Allow calling realloc without knowing block size
X-Git-Tag: 2.4.0~342
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=5e92a5ebcadeebc9927eefa70bed7b6c9f8b5131;p=thirdparty%2Fdovecot%2Fcore.git

lib: mempool - Allow calling realloc without knowing block size

Supported by some pools only
---

diff --git a/src/lib/mempool-allocfree.c b/src/lib/mempool-allocfree.c
index 3bbc642ae5..239db03e0e 100644
--- a/src/lib/mempool-allocfree.c
+++ b/src/lib/mempool-allocfree.c
@@ -283,6 +283,8 @@ static void *pool_allocfree_realloc(pool_t pool, void *mem,
 	unsigned char *new_mem;
 
 	struct pool_block *block = pool_block_detach(apool, mem);
+	if (old_size == SIZE_MAX)
+		old_size = block->size;
 	if ((new_mem = realloc(block, SIZEOF_POOLBLOCK+new_size)) == NULL)
 		i_fatal_status(FATAL_OUTOFMEM, "realloc(block, %zu)",
 			       SIZEOF_POOLBLOCK+new_size);
diff --git a/src/lib/mempool-alloconly.c b/src/lib/mempool-alloconly.c
index 798ea84f90..79823dc204 100644
--- a/src/lib/mempool-alloconly.c
+++ b/src/lib/mempool-alloconly.c
@@ -467,6 +467,8 @@ static void *pool_alloconly_realloc(pool_t pool, void *mem,
 		container_of(pool, struct alloconly_pool, pool);
 	unsigned char *new_mem;
 
+	i_assert(old_size < SIZE_MAX);
+
 	if (new_size <= old_size)
 		return mem;
 
diff --git a/src/lib/mempool-datastack.c b/src/lib/mempool-datastack.c
index 6905f9592e..a1985dc3ae 100644
--- a/src/lib/mempool-datastack.c
+++ b/src/lib/mempool-datastack.c
@@ -162,6 +162,8 @@ static void *pool_data_stack_realloc(pool_t pool, void *mem,
 		container_of(pool, struct datastack_pool, pool);
 	void *new_mem;
 
+	i_assert(old_size < SIZE_MAX);
+
 	/* @UNSAFE */
 	if (unlikely(dpool->data_stack_frame != data_stack_frame_id))
 		i_panic("pool_data_stack_realloc(): stack frame changed");
diff --git a/src/lib/mempool-unsafe-datastack.c b/src/lib/mempool-unsafe-datastack.c
index 394fdeb6a1..08649989c1 100644
--- a/src/lib/mempool-unsafe-datastack.c
+++ b/src/lib/mempool-unsafe-datastack.c
@@ -110,6 +110,8 @@ static void *pool_unsafe_data_stack_realloc(pool_t pool ATTR_UNUSED,
 {
 	void *new_mem;
 
+	i_assert(old_size < SIZE_MAX);
+
 	/* @UNSAFE */
 	if (old_size >= new_size)
 		return mem;
diff --git a/src/lib/mempool.h b/src/lib/mempool.h
index d7100e21cb..a80303b610 100644
--- a/src/lib/mempool.h
+++ b/src/lib/mempool.h
@@ -121,6 +121,8 @@ p_malloc(pool_t pool, size_t size)
 	return pool->v->malloc(pool, size);
 }
 
+/* For allocfree and system pools you can use SIZE_MAX
+   to indicate that you have no knowlege of the old size. */
 static inline void * ATTR_WARN_UNUSED_RESULT ATTR_RETURNS_NONNULL
 p_realloc(pool_t pool, void *mem, size_t old_size, size_t new_size)
 {