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[PATCH 05/18] tag: use strbuf to format tag header

From
Jeff King <peff@peff.net>
Date
Mar 28, 2017, 19:46 UTC
Message-ID
<20170328194623.sv2sih2s7q533zgf@sigill.intra.peff.net>
In-Reply-To
<20170328194255.vf7nfzzmmzxsbn36@sigill.intra.peff.net>

We format the tag header into a fixed 1024-byte buffer. But since the tag-name and tagger ident can be arbitrarily large, we may unceremoniously die with "tag header too big". Let's just use a strbuf instead.

Note that it looks at first glance like we can just format this directly into the "buf" strbuf where it will ultimately go. But that buffer may already contain the tag message, and we have no easy way to prepend formatted data to a strbuf (we can only splice in an already-generated buffer). This isn't a performance-critical path, so going through an extra buffer isn't a big deal.

Signed-off-by: Jeff King <peff@peff.net>
---
 builtin/tag.c | 27 ++++++++++++---------------
 1 file changed, 12 insertions(+), 15 deletions(-)
diff --git a/builtin/tag.c b/builtin/tag.c
index ad29be692..045e7ad23 100644
--- a/builtin/tag.c
+++ b/builtin/tag.c
@@ -231,26 +231,22 @@ static void create_tag(const unsigned char *object, const char *tag,
 		       unsigned char *prev, unsigned char *result)
 {
 	enum object_type type;
-	char header_buf[1024];
-	int header_len;
+	struct strbuf header = STRBUF_INIT;
 	char *path = NULL;
 
 	type = sha1_object_info(object, NULL);
 	if (type <= OBJ_NONE)
 	    die(_("bad object type."));
 
-	header_len = snprintf(header_buf, sizeof(header_buf),
-			  "object %s\n"
-			  "type %s\n"
-			  "tag %s\n"
-			  "tagger %s\n\n",
-			  sha1_to_hex(object),
-			  typename(type),
-			  tag,
-			  git_committer_info(IDENT_STRICT));
-
-	if (header_len > sizeof(header_buf) - 1)
-		die(_("tag header too big."));
+	strbuf_addf(&header,
+		    "object %s\n"
+		    "type %s\n"
+		    "tag %s\n"
+		    "tagger %s\n\n",
+		    sha1_to_hex(object),
+		    typename(type),
+		    tag,
+		    git_committer_info(IDENT_STRICT));
 
 	if (!opt->message_given) {
 		int fd;
@@ -288,7 +284,8 @@ static void create_tag(const unsigned char *object, const char *tag,
 	if (!opt->message_given && !buf->len)
 		die(_("no tag message?"));
 
-	strbuf_insert(buf, 0, header_buf, header_len);
+	strbuf_insert(buf, 0, header.buf, header.len);
+	strbuf_release(&header);
 
 	if (build_tag_object(buf, opt->sign, result) < 0) {
 		if (path)
-- 
2.12.2.845.g55fcf8b10
Previous: Jeff KingNext: Jeff King
Message 5 of 30 in “snprintf cleanups”
  1. 0/18 snprintf cleanupsJeff King, Mar 28, 2017
  2. 01/18 do not check odb_mkstemp return value for errorsJeff King, Mar 28, 2017
  3. 02/18 odb_mkstemp: write filename into strbufJeff King, Mar 28, 2017
  4. 03/18 odb_mkstemp: use git_path_bufJeff King, Mar 28, 2017
  5. 05/18 tag: use strbuf to format tag headerJeff King, Mar 28, 2017
  6. 09/18 create_branch: move msg setup closer to point of useJeff King, Mar 28, 2017
  7. 08/18 avoid using mksnpath for refsJeff King, Mar 28, 2017
  8. 06/18 fetch: use heap buffer to format reflogJeff King, Mar 28, 2017
  9. 04/18 diff: avoid fixed-size buffer for patch-idsJeff King, Mar 28, 2017
  10. Jeff KingMar 28, 2017
  11. 13/18 replace unchecked snprintf calls with heap buffersJeff King, Mar 28, 2017
  12. 12/18 receive-pack: print --pack-header directly into argv arrayJeff King, Mar 28, 2017
  13. 07/18 avoid using fixed PATH_MAX buffers for refsJeff King, Mar 28, 2017
  14. Junio C HamanoApr 17, 2017
  15. Jeff KingApr 18, 2017
  16. Junio C HamanoApr 18, 2017
  17. 11/18 name-rev: replace static buffer with strbufJeff King, Mar 28, 2017
  18. 15/18 convert unchecked snprintf into xsnprintfJeff King, Mar 28, 2017
  19. 10/18 create_branch: use xstrfmt for reflog messageJeff King, Mar 28, 2017
  20. 14/18 combine-diff: replace malloc/snprintf with xstrfmtJeff King, Mar 28, 2017
  21. 17/18 gc: replace local buffer with git_pathJeff King, Mar 28, 2017
  22. 16/18 transport-helper: replace checked snprintf with xsnprintfJeff King, Mar 28, 2017
  23. 18/18 daemon: use an argv_array to exec childrenJeff King, Mar 28, 2017
  24. Junio C HamanoMar 28, 2017
  25. Jeff KingMar 29, 2017
  26. Junio C HamanoMar 29, 2017
  27. Jeff KingMar 30, 2017
  28. Junio C HamanoMar 30, 2017
  29. Jeff KingMar 30, 2017
  30. Makefile: detect errors in running spatchJeff King, Mar 29, 2017

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