find_unique_abbrev: use 4-buffer ring

Some code paths want to format multiple abbreviated sha1s in
the same output line. Because we use a single static buffer
for our return value, they have to either break their output
into several calls or allocate their own arrays and use
find_unique_abbrev_r().

Intead, let's mimic sha1_to_hex() and use a ring of several
buffers, so that the return value stays valid through
multiple calls. This shortens some of the callers, and makes
it harder to for them to make a silly mistake.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/builtin/merge.c b/builtin/merge.c
index a8b57c7d9856518fdcd4c3819f0656544eadf022..b65eeaa87d303b027230bf2479f78c15a02ca08a 100644 (file)
--- a/builtin/merge.c
+++ b/builtin/merge.c
@@ -1374,12 +1374,11 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
                struct commit *commit;
 
                if (verbosity >= 0) {
-                       char from[GIT_SHA1_HEXSZ + 1], to[GIT_SHA1_HEXSZ + 1];
-                       find_unique_abbrev_r(from, head_commit->object.oid.hash,
-                                             DEFAULT_ABBREV);
-                       find_unique_abbrev_r(to, remoteheads->item->object.oid.hash,
-                                             DEFAULT_ABBREV);
-                       printf(_("Updating %s..%s\n"), from, to);
+                       printf(_("Updating %s..%s\n"),
+                              find_unique_abbrev(head_commit->object.oid.hash,
+                                                 DEFAULT_ABBREV),
+                              find_unique_abbrev(remoteheads->item->object.oid.hash,
+                                                 DEFAULT_ABBREV));
                }
                strbuf_addstr(&msg, "Fast-forward");
                if (have_message)

diff --git a/builtin/receive-pack.c b/builtin/receive-pack.c
index 04ed38e17db67845ec5da34031f10a894d933bdc..680759d256a14917945a96dd16253606a88a5f8e 100644 (file)
--- a/builtin/receive-pack.c
+++ b/builtin/receive-pack.c
@@ -1163,10 +1163,6 @@ static void check_aliased_update(struct command *cmd, struct string_list *list)
        struct string_list_item *item;
        struct command *dst_cmd;
        unsigned char sha1[GIT_SHA1_RAWSZ];
-       char cmd_oldh[GIT_SHA1_HEXSZ + 1],
-            cmd_newh[GIT_SHA1_HEXSZ + 1],
-            dst_oldh[GIT_SHA1_HEXSZ + 1],
-            dst_newh[GIT_SHA1_HEXSZ + 1];
        int flag;
 
        strbuf_addf(&buf, "%s%s", get_git_namespace(), cmd->ref_name);
@@ -1197,14 +1193,14 @@ static void check_aliased_update(struct command *cmd, struct string_list *list)
 
        dst_cmd->skip_update = 1;
 
-       find_unique_abbrev_r(cmd_oldh, cmd->old_sha1, DEFAULT_ABBREV);
-       find_unique_abbrev_r(cmd_newh, cmd->new_sha1, DEFAULT_ABBREV);
-       find_unique_abbrev_r(dst_oldh, dst_cmd->old_sha1, DEFAULT_ABBREV);
-       find_unique_abbrev_r(dst_newh, dst_cmd->new_sha1, DEFAULT_ABBREV);
        rp_error("refusing inconsistent update between symref '%s' (%s..%s) and"
                 " its target '%s' (%s..%s)",
-                cmd->ref_name, cmd_oldh, cmd_newh,
-                dst_cmd->ref_name, dst_oldh, dst_newh);
+                cmd->ref_name,
+                find_unique_abbrev(cmd->old_sha1, DEFAULT_ABBREV),
+                find_unique_abbrev(cmd->new_sha1, DEFAULT_ABBREV),
+                dst_cmd->ref_name,
+                find_unique_abbrev(dst_cmd->old_sha1, DEFAULT_ABBREV),
+                find_unique_abbrev(dst_cmd->new_sha1, DEFAULT_ABBREV));
 
        cmd->error_string = dst_cmd->error_string =
                "inconsistent aliased update";

diff --git a/cache.h b/cache.h
index f7ee4145634762a42663df3c69b095d64d919d01..607fe6ed30f6003009217ec22de13873e57589b4 100644 (file)
--- a/cache.h
+++ b/cache.h
@@ -903,8 +903,8 @@ extern char *sha1_pack_index_name(const unsigned char *sha1);
  * The result will be at least `len` characters long, and will be NUL
  * terminated.
  *
- * The non-`_r` version returns a static buffer which will be overwritten by
- * subsequent calls.
+ * The non-`_r` version returns a static buffer which remains valid until 4
+ * more calls to find_unique_abbrev are made.
  *
  * The `_r` variant writes to a buffer supplied by the caller, which must be at
  * least `GIT_SHA1_HEXSZ + 1` bytes. The return value is the number of bytes

diff --git a/sha1_name.c b/sha1_name.c
index 409283614679b625f1cb6d191f1a2a32423bbcda..36ce9b9f45041c6e17e763cee259c284312dc42c 100644 (file)
--- a/sha1_name.c
+++ b/sha1_name.c
@@ -472,7 +472,9 @@ int find_unique_abbrev_r(char *hex, const unsigned char *sha1, int len)
 
 const char *find_unique_abbrev(const unsigned char *sha1, int len)
 {
-       static char hex[GIT_SHA1_HEXSZ + 1];
+       static int bufno;
+       static char hexbuffer[4][GIT_SHA1_HEXSZ + 1];
+       char *hex = hexbuffer[3 & ++bufno];
        find_unique_abbrev_r(hex, sha1, len);
        return hex;
 }