Tutorial: adjust merge example to recursive strategy.
[gitweb.git] / sha1_name.c
index 0225f3107eaac6cb2824a90f1e4ced66f0c33852..faac158b16ca978914696ed5d2801770a122cce2 100644 (file)
@@ -1,5 +1,8 @@
 #include "cache.h"
+#include "tag.h"
 #include "commit.h"
+#include "tree.h"
+#include "blob.h"
 
 static int find_short_object_filename(int len, const char *name, unsigned char *sha1)
 {
@@ -91,14 +94,23 @@ static int find_short_packed_object(int len, const unsigned char *match, unsigne
                        last = mid;
                }
                if (first < num) {
-                       unsigned char now[20];
+                       unsigned char now[20], next[20];
                        nth_packed_object_sha1(p, first, now);
                        if (match_sha(len, match, now)) {
-                               if (!found) {
-                                       memcpy(found_sha1, now, 20);
-                                       found++;
+                               if (nth_packed_object_sha1(p, first+1, next) ||
+                                   !match_sha(len, match, next)) {
+                                       /* unique within this pack */
+                                       if (!found) {
+                                               memcpy(found_sha1, now, 20);
+                                               found++;
+                                       }
+                                       else if (memcmp(found_sha1, now, 20)) {
+                                               found = 2;
+                                               break;
+                                       }
                                }
-                               else if (memcmp(found_sha1, now, 20)) {
+                               else {
+                                       /* not even unique within this pack */
                                        found = 2;
                                        break;
                                }
@@ -110,6 +122,9 @@ static int find_short_packed_object(int len, const unsigned char *match, unsigne
        return found;
 }
 
+#define SHORT_NAME_NOT_FOUND (-1)
+#define SHORT_NAME_AMBIGUOUS (-2)
+
 static int find_unique_short_object(int len, char *canonical,
                                    unsigned char *res, unsigned char *sha1)
 {
@@ -119,23 +134,24 @@ static int find_unique_short_object(int len, char *canonical,
        has_unpacked = find_short_object_filename(len, canonical, unpacked_sha1);
        has_packed = find_short_packed_object(len, res, packed_sha1);
        if (!has_unpacked && !has_packed)
-               return -1;
+               return SHORT_NAME_NOT_FOUND;
        if (1 < has_unpacked || 1 < has_packed)
-               return -1;
+               return SHORT_NAME_AMBIGUOUS;
        if (has_unpacked != has_packed) {
                memcpy(sha1, (has_packed ? packed_sha1 : unpacked_sha1), 20);
                return 0;
        }
        /* Both have unique ones -- do they match? */
        if (memcmp(packed_sha1, unpacked_sha1, 20))
-               return -1;
+               return -2;
        memcpy(sha1, packed_sha1, 20);
        return 0;
 }
 
-static int get_short_sha1(const char *name, int len, unsigned char *sha1)
+static int get_short_sha1(const char *name, int len, unsigned char *sha1,
+                         int quietly)
 {
-       int i;
+       int i, status;
        char canonical[40];
        unsigned char res[20];
 
@@ -162,7 +178,52 @@ static int get_short_sha1(const char *name, int len, unsigned char *sha1)
                res[i >> 1] |= val;
        }
 
-       return find_unique_short_object(i, canonical, res, sha1);
+       status = find_unique_short_object(i, canonical, res, sha1);
+       if (!quietly && (status == SHORT_NAME_AMBIGUOUS))
+               return error("short SHA1 %.*s is ambiguous.", len, canonical);
+       return status;
+}
+
+const char *find_unique_abbrev(const unsigned char *sha1, int len)
+{
+       int status;
+       static char hex[41];
+       memcpy(hex, sha1_to_hex(sha1), 40);
+       while (len < 40) {
+               unsigned char sha1_ret[20];
+               status = get_short_sha1(hex, len, sha1_ret, 1);
+               if (!status) {
+                       hex[len] = 0;
+                       return hex;
+               }
+               if (status != SHORT_NAME_AMBIGUOUS)
+                       return NULL;
+               len++;
+       }
+       return NULL;
+}
+
+static int ambiguous_path(const char *path)
+{
+       int slash = 1;
+
+       for (;;) {
+               switch (*path++) {
+               case '\0':
+                       break;
+               case '/':
+                       if (slash)
+                               break;
+                       slash = 1;
+                       continue;
+               case '.':
+                       continue;
+               default:
+                       slash = 0;
+                       continue;
+               }
+               return slash;
+       }
 }
 
 static int get_sha1_basic(const char *str, int len, unsigned char *sha1)
@@ -175,16 +236,31 @@ static int get_sha1_basic(const char *str, int len, unsigned char *sha1)
                NULL
        };
        const char **p;
+       int found = 0;
 
        if (len == 40 && !get_sha1_hex(str, sha1))
                return 0;
 
+       /* Accept only unambiguous ref paths. */
+       if (ambiguous_path(str))
+               return -1;
+
        for (p = prefix; *p; p++) {
                char *pathname = git_path("%s/%.*s", *p, len, str);
-               if (!read_ref(pathname, sha1))
-                       return 0;
+               if (!read_ref(pathname, sha1)) {
+                       /* Must be unique; i.e. when heads/foo and
+                        * tags/foo are both present, reject "foo".
+                        * Note that read_ref() eventually calls
+                        * get_sha1_hex() which can smudge initial
+                        * part of the buffer even if what is read
+                        * is found to be invalid halfway.
+                        */
+                       if (1 < found++)
+                               return -1;
+               }
        }
-
+       if (found == 1)
+               return 0;
        return -1;
 }
 
@@ -239,6 +315,84 @@ static int get_nth_ancestor(const char *name, int len,
        return 0;
 }
 
+static int peel_onion(const char *name, int len, unsigned char *sha1)
+{
+       unsigned char outer[20];
+       const char *sp;
+       const char *type_string = NULL;
+       struct object *o;
+
+       /*
+        * "ref^{type}" dereferences ref repeatedly until you cannot
+        * dereference anymore, or you get an object of given type,
+        * whichever comes first.  "ref^{}" means just dereference
+        * tags until you get a non-tag.  "ref^0" is a shorthand for
+        * "ref^{commit}".  "commit^{tree}" could be used to find the
+        * top-level tree of the given commit.
+        */
+       if (len < 4 || name[len-1] != '}')
+               return -1;
+
+       for (sp = name + len - 1; name <= sp; sp--) {
+               int ch = *sp;
+               if (ch == '{' && name < sp && sp[-1] == '^')
+                       break;
+       }
+       if (sp <= name)
+               return -1;
+
+       sp++; /* beginning of type name, or closing brace for empty */
+       if (!strncmp(commit_type, sp, 6) && sp[6] == '}')
+               type_string = commit_type;
+       else if (!strncmp(tree_type, sp, 4) && sp[4] == '}')
+               type_string = tree_type;
+       else if (!strncmp(blob_type, sp, 4) && sp[4] == '}')
+               type_string = blob_type;
+       else if (sp[0] == '}')
+               type_string = NULL;
+       else
+               return -1;
+
+       if (get_sha1_1(name, sp - name - 2, outer))
+               return -1;
+
+       o = parse_object(outer);
+       if (!o)
+               return -1;
+       if (!type_string) {
+               o = deref_tag(o, name, sp - name - 2);
+               if (!o || (!o->parsed && !parse_object(o->sha1)))
+                       return -1;
+               memcpy(sha1, o->sha1, 20);
+       }
+       else {
+               /* At this point, the syntax look correct, so
+                * if we do not get the needed object, we should
+                * barf.
+                */
+
+               while (1) {
+                       if (!o || (!o->parsed && !parse_object(o->sha1)))
+                               return -1;
+                       if (o->type == type_string) {
+                               memcpy(sha1, o->sha1, 20);
+                               return 0;
+                       }
+                       if (o->type == tag_type)
+                               o = ((struct tag*) o)->tagged;
+                       else if (o->type == commit_type)
+                               o = &(((struct commit *) o)->tree->object);
+                       else
+                               return error("%.*s: expected %s type, but the object dereferences to %s type",
+                                            len, name, type_string,
+                                            o->type);
+                       if (!o->parsed)
+                               parse_object(o->sha1);
+               }
+       }
+       return 0;
+}
+
 static int get_sha1_1(const char *name, int len, unsigned char *sha1)
 {
        int parent, ret;
@@ -280,10 +434,14 @@ static int get_sha1_1(const char *name, int len, unsigned char *sha1)
                return get_nth_ancestor(name, len1, sha1, parent);
        }
 
+       ret = peel_onion(name, len, sha1);
+       if (!ret)
+               return 0;
+
        ret = get_sha1_basic(name, len, sha1);
        if (!ret)
                return 0;
-       return get_short_sha1(name, len, sha1);
+       return get_short_sha1(name, len, sha1, 0);
 }
 
 /*