find_unique_abbrev() simplification.

Earlier it did not grok the 0{40} SHA1 very well, but what it
needed to do was to find the shortest 0{N} that is not used as a
valid object name to be consistent with the way names of valid
objects are abbreviated.  This makes some users simpler.

Signed-off-by: Junio C Hamano <junkio@cox.net>

diff --git a/combine-diff.c b/combine-diff.c
index 9aa099b..8ba6949 100644 (file)
--- a/combine-diff.c
+++ b/combine-diff.c
@@ -716,10 +716,7 @@ static int show_patch_diff(struct combine_diff_path *elem, int num_parent,
 
        if (show_hunks || mode_differs) {
                const char *abb;
-               char null_abb[DEFAULT_ABBREV + 1];
 
-               memset(null_abb, '0', DEFAULT_ABBREV);
-               null_abb[DEFAULT_ABBREV] = 0;
                if (header) {
                        shown_header++;
                        puts(header);
@@ -734,17 +731,11 @@ static int show_patch_diff(struct combine_diff_path *elem, int num_parent,
                for (i = 0; i < num_parent; i++) {
                        if (elem->parent[i].mode != elem->mode)
                                mode_differs = 1;
-                       if (memcmp(elem->parent[i].sha1, null_sha1, 20))
-                               abb = find_unique_abbrev(elem->parent[i].sha1,
-                                                        DEFAULT_ABBREV);
-                       else
-                               abb = null_abb;
+                       abb = find_unique_abbrev(elem->parent[i].sha1,
+                                                DEFAULT_ABBREV);
                        printf("%s%s", i ? "," : "", abb);
                }
-               if (memcmp(elem->sha1, null_sha1, 20))
-                       abb = find_unique_abbrev(elem->sha1, DEFAULT_ABBREV);
-               else
-                       abb = null_abb;
+               abb = find_unique_abbrev(elem->sha1, DEFAULT_ABBREV);
                printf("..%s\n", abb);
 
                if (mode_differs) {

diff --git a/diff.c b/diff.c
index ec51e7d..890bdaa 100644 (file)
--- a/diff.c
+++ b/diff.c
@@ -963,7 +963,7 @@ void diff_free_filepair(struct diff_filepair *p)
 }
 
 /* This is different from find_unique_abbrev() in that
- * it needs to deal with 0{40} SHA1.
+ * it stuffs the result with dots for alignment.
  */
 const char *diff_unique_abbrev(const unsigned char *sha1, int len)
 {
@@ -973,16 +973,8 @@ const char *diff_unique_abbrev(const unsigned char *sha1, int len)
                return sha1_to_hex(sha1);
 
        abbrev = find_unique_abbrev(sha1, len);
-       if (!abbrev) {
-               if (!memcmp(sha1, null_sha1, 20)) {
-                       char *buf = sha1_to_hex(null_sha1);
-                       if (len < 37)
-                               strcpy(buf + len, "...");
-                       return buf;
-               }
-               else 
-                       return sha1_to_hex(sha1);
-       }
+       if (!abbrev)
+               return sha1_to_hex(sha1);
        abblen = strlen(abbrev);
        if (abblen < 37) {
                static char hex[41];

diff --git a/sha1_name.c b/sha1_name.c
index fa85d8a..d67de18 100644 (file)
--- a/sha1_name.c
+++ b/sha1_name.c
@@ -186,16 +186,18 @@ static int get_short_sha1(const char *name, int len, unsigned char *sha1,
 
 const char *find_unique_abbrev(const unsigned char *sha1, int len)
 {
-       int status;
+       int status, is_null;
        static char hex[41];
 
+       is_null = !memcmp(sha1, null_sha1, 20);
        memcpy(hex, sha1_to_hex(sha1), 40);
        if (len == 40)
                return hex;
        while (len < 40) {
                unsigned char sha1_ret[20];
                status = get_short_sha1(hex, len, sha1_ret, 1);
-               if (!status) {
+               if (!status ||
+                   (is_null && status != SHORT_NAME_AMBIGUOUS)) {
                        hex[len] = 0;
                        return hex;
                }