From: Emil Velikov <emil.l.velikov@gmail.com>
Date: Sun, 2 Aug 2026 12:26:13 +0000 (+0100)
Subject: shared/strbuf: make strbuf_reserve_extra public
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=44cdb6fa55f5790b9d1615eb709a1329649f5686;p=thirdparty%2Fkmod.git

shared/strbuf: make strbuf_reserve_extra public

We'll need the function shortly, so make it public (within kmod).
In the process, re-introduce the test with some changes:
 - cosmetics - test function signature, new test macros, DECLARE_*
 - do not request an extra byte for \0
 - check both ::size and ::bytes

Signed-off-by: Emil Velikov <emil.l.velikov@gmail.com>
Link: https://github.com/kmod-project/kmod/pull/451
Signed-off-by: Lucas De Marchi <demarchi@kernel.org>
---

diff --git a/shared/strbuf.c b/shared/strbuf.c
index 76aab07..1499b6d 100644
--- a/shared/strbuf.c
+++ b/shared/strbuf.c
@@ -33,7 +33,7 @@ static bool buf_realloc(struct strbuf *buf, size_t sz)
 	return true;
 }
 
-static bool strbuf_reserve_extra(struct strbuf *buf, size_t n)
+bool strbuf_reserve_extra(struct strbuf *buf, size_t n)
 {
 	if (n < buf->size - buf->used)
 		return true;
diff --git a/shared/strbuf.h b/shared/strbuf.h
index 074699a..20ed7a2 100644
--- a/shared/strbuf.h
+++ b/shared/strbuf.h
@@ -50,6 +50,16 @@ void strbuf_clear(struct strbuf *buf);
  */
 const char *strbuf_str(struct strbuf *buf);
 
+/*
+ * Reserve/allocate extra space to buf.
+ *
+ * Check the current buf size and re-allocate, as needed. Therefore follow-up pushes of the
+ * given size (or less) are guaranteed to a) not require re-allocation and b) succeed.
+ *
+ * The terminating \0 byte will be handled internally.
+ */
+bool strbuf_reserve_extra(struct strbuf *buf, size_t n);
+
 bool strbuf_pushchar(struct strbuf *buf, char ch);
 size_t strbuf_pushmem(struct strbuf *buf, const char *src, size_t sz);
 static inline size_t strbuf_pushchars(struct strbuf *buf, const char *str)
diff --git a/testsuite/test-shared.c b/testsuite/test-shared.c
index b12051d..b45162d 100644
--- a/testsuite/test-shared.c
+++ b/testsuite/test-shared.c
@@ -626,6 +626,30 @@ static int test_strbuf_used(void)
 }
 DEFINE_TEST(test_strbuf_used, .description = "test strbuf_used");
 
+static int test_strbuf_reserve_extra(void)
+{
+	DECLARE_STRBUF(buf);
+	const char *str;
+	size_t size;
+
+	strbuf_reserve_extra(&buf, strlen(TEXT));
+	size = buf.size;
+	str = buf.bytes;
+	TS_ASSERT(size >= strlen(TEXT) + 1);
+
+	strbuf_pushchars(&buf, TEXT);
+	TS_ASSERT(size == buf.size);
+	TS_ASSERT(str == buf.bytes);
+
+	strbuf_clear(&buf);
+	strbuf_pushchars(&buf, TEXT);
+	TS_ASSERT(size == buf.size);
+	TS_ASSERT(str == buf.bytes);
+
+	return 0;
+}
+DEFINE_TEST(test_strbuf_reserve_extra, .description = "test strbuf_reserve_extra");
+
 static int test_strbuf_shrink_to(void)
 {
 	_cleanup_strbuf_ struct strbuf buf;