path: root/strbuf.h
diff options
authorJonathan Nieder <>2017-10-04 02:39:54 (GMT)
committerJunio C Hamano <>2017-10-04 06:21:52 (GMT)
commite0222159fa53ea24785cfb1dc5de0214e89b0117 (patch)
tree532cfcd58b57d1d7ec9f877ebbd483afd9919091 /strbuf.h
parent4010f1d1b782eb7585e0e0abcefa794bd5ff29a0 (diff)
strbuf doc: reuse after strbuf_release is fine
strbuf_release leaves the strbuf in a valid, initialized state, so there is no need to call strbuf_init after it. Moreover, this is not likely to change in the future: strbuf_release leaving the strbuf in a valid state has been easy to maintain and has been very helpful for Git's robustness and simplicity (e.g., preventing use-after-free vulnerabilities). Document the semantics so the next generation of Git developers can become familiar with them without reading the implementation. It is still not advisable to call strbuf_release too often because it is wasteful, so add a note pointing to strbuf_reset for that. The same semantics apply to strbuf_detach. Add a similar note to its docstring to make that clear. Improved-by: Jeff King <> Signed-off-by: Jonathan Nieder <> Signed-off-by: Junio C Hamano <>
Diffstat (limited to 'strbuf.h')
1 files changed, 9 insertions, 2 deletions
diff --git a/strbuf.h b/strbuf.h
index 2075384..80112a8 100644
--- a/strbuf.h
+++ b/strbuf.h
@@ -82,8 +82,12 @@ extern char strbuf_slopbuf[];
extern void strbuf_init(struct strbuf *, size_t);
- * Release a string buffer and the memory it used. You should not use the
- * string buffer after using this function, unless you initialize it again.
+ * Release a string buffer and the memory it used. After this call, the
+ * strbuf points to an empty string that does not need to be free()ed, as
+ * if it had been set to `STRBUF_INIT` and never modified.
+ *
+ * To clear a strbuf in preparation for further use without the overhead
+ * of free()ing and malloc()ing again, use strbuf_reset() instead.
extern void strbuf_release(struct strbuf *);
@@ -91,6 +95,9 @@ extern void strbuf_release(struct strbuf *);
* Detach the string from the strbuf and returns it; you now own the
* storage the string occupies and it is your responsibility from then on
* to release it with `free(3)` when you are done with it.
+ *
+ * The strbuf that previously held the string is reset to `STRBUF_INIT` so
+ * it can be reused after calling this function.
extern char *strbuf_detach(struct strbuf *, size_t *);