[PATCH v5 1/4] strbuf: pass correct alloc to strbuf_attach() in strbuf_reencode()

From: Vaidas Pilkauskas via GitGitGadget <gitgitgadget@gmail.com>
Date: Feb 23, 2026, 14:20 UTC
Message-ID: <7ec2d6644785827c047a55a99b213468583c6c1a.1771856405.git.gitgitgadget@gmail.com>
In-Reply-To: <pull.2008.v5.git.1771856405.gitgitgadget@gmail.com>

From: Vaidas Pilkauskas <vaidas.pilkauskas@shopify.com>

reencode_string_len() allocates len+1 bytes (including the NUL) and returns the string length in len. strbuf_reencode() was calling strbuf_attach(sb, out, len, len), so alloc was one byte too small.

strbuf_attach() then calls strbuf_grow(sb, 0). With alloc < len+1, ALLOC_GROW always reallocates, so we reallocated immediately after attach even when the strbuf was not extended further. Pass len+1 as the alloc argument so the existing buffer is reused and the reallocation is avoided.

Signed-off-by: Vaidas Pilkauskas <vaidas.pilkauskas@shopify.com>
---
 strbuf.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/strbuf.c b/strbuf.c
index 3939863cf3..3e04addc22 100644
--- a/strbuf.c
+++ b/strbuf.c
@@ -168,7 +168,7 @@ int strbuf_reencode(struct strbuf *sb, const char *from, const char *to)
 	if (!out)
 		return -1;
 
-	strbuf_attach(sb, out, len, len);
+	strbuf_attach(sb, out, len, len + 1);
 	return 0;
 }

-- 
gitgitgadget