Documentation/git-update-index: explain splitIndex.*
[gitweb.git] / sha1_name.c
index ca7ddd6f2cf7074a1d74e011c2bd260c2ae6ffe6..73a915ff1b3278f08ef4f327a55fe61d238f720a 100644 (file)
@@ -7,15 +7,20 @@
 #include "refs.h"
 #include "remote.h"
 #include "dir.h"
+#include "sha1-array.h"
 
 static int get_sha1_oneline(const char *, unsigned char *, struct commit_list *);
 
 typedef int (*disambiguate_hint_fn)(const unsigned char *, void *);
 
 struct disambiguate_state {
+       int len; /* length of prefix in hex chars */
+       char hex_pfx[GIT_SHA1_HEXSZ + 1];
+       unsigned char bin_pfx[GIT_SHA1_RAWSZ];
+
        disambiguate_hint_fn fn;
        void *cb_data;
-       unsigned char candidate[20];
+       unsigned char candidate[GIT_SHA1_RAWSZ];
        unsigned candidate_exists:1;
        unsigned candidate_checked:1;
        unsigned candidate_ok:1;
@@ -72,10 +77,10 @@ static void update_candidates(struct disambiguate_state *ds, const unsigned char
        /* otherwise, current can be discarded and candidate is still good */
 }
 
-static void find_short_object_filename(int len, const char *hex_pfx, struct disambiguate_state *ds)
+static void find_short_object_filename(struct disambiguate_state *ds)
 {
        struct alternate_object_database *alt;
-       char hex[40];
+       char hex[GIT_SHA1_HEXSZ];
        static struct alternate_object_database *fakeent;
 
        if (!fakeent) {
@@ -86,25 +91,18 @@ static void find_short_object_filename(int len, const char *hex_pfx, struct disa
                 * alt->name/alt->base while iterating over the
                 * object databases including our own.
                 */
-               const char *objdir = get_object_directory();
-               size_t objdir_len = strlen(objdir);
-               fakeent = xmalloc(st_add3(sizeof(*fakeent), objdir_len, 43));
-               memcpy(fakeent->base, objdir, objdir_len);
-               fakeent->name = fakeent->base + objdir_len + 1;
-               fakeent->name[-1] = '/';
+               fakeent = alloc_alt_odb(get_object_directory());
        }
        fakeent->next = alt_odb_list;
 
-       xsnprintf(hex, sizeof(hex), "%.2s", hex_pfx);
+       xsnprintf(hex, sizeof(hex), "%.2s", ds->hex_pfx);
        for (alt = fakeent; alt && !ds->ambiguous; alt = alt->next) {
+               struct strbuf *buf = alt_scratch_buf(alt);
                struct dirent *de;
                DIR *dir;
-               /*
-                * every alt_odb struct has 42 extra bytes after the base
-                * for exactly this purpose
-                */
-               xsnprintf(alt->name, 42, "%.2s/", hex_pfx);
-               dir = opendir(alt->base);
+
+               strbuf_addf(buf, "%.2s/", ds->hex_pfx);
+               dir = opendir(buf->buf);
                if (!dir)
                        continue;
 
@@ -113,7 +111,7 @@ static void find_short_object_filename(int len, const char *hex_pfx, struct disa
 
                        if (strlen(de->d_name) != 38)
                                continue;
-                       if (memcmp(de->d_name, hex_pfx + 2, len - 2))
+                       if (memcmp(de->d_name, ds->hex_pfx + 2, ds->len - 2))
                                continue;
                        memcpy(hex + 2, de->d_name, 38);
                        if (!get_sha1_hex(hex, sha1))
@@ -138,9 +136,7 @@ static int match_sha(unsigned len, const unsigned char *a, const unsigned char *
        return 1;
 }
 
-static void unique_in_pack(int len,
-                         const unsigned char *bin_pfx,
-                          struct packed_git *p,
+static void unique_in_pack(struct packed_git *p,
                           struct disambiguate_state *ds)
 {
        uint32_t num, last, i, first = 0;
@@ -155,7 +151,7 @@ static void unique_in_pack(int len,
                int cmp;
 
                current = nth_packed_object_sha1(p, mid);
-               cmp = hashcmp(bin_pfx, current);
+               cmp = hashcmp(ds->bin_pfx, current);
                if (!cmp) {
                        first = mid;
                        break;
@@ -174,20 +170,19 @@ static void unique_in_pack(int len,
         */
        for (i = first; i < num && !ds->ambiguous; i++) {
                current = nth_packed_object_sha1(p, i);
-               if (!match_sha(len, bin_pfx, current))
+               if (!match_sha(ds->len, ds->bin_pfx, current))
                        break;
                update_candidates(ds, current);
        }
 }
 
-static void find_short_packed_object(int len, const unsigned char *bin_pfx,
-                                    struct disambiguate_state *ds)
+static void find_short_packed_object(struct disambiguate_state *ds)
 {
        struct packed_git *p;
 
        prepare_packed_git();
        for (p = packed_git; p && !ds->ambiguous; p = p->next)
-               unique_in_pack(len, bin_pfx, p, ds);
+               unique_in_pack(p, ds);
 }
 
 #define SHORT_NAME_NOT_FOUND (-1)
@@ -269,7 +264,7 @@ static int disambiguate_treeish_only(const unsigned char *sha1, void *cb_data_un
                return 0;
 
        /* We need to do this the hard way... */
-       obj = deref_tag(lookup_object(sha1), NULL, 0);
+       obj = deref_tag(parse_object(sha1), NULL, 0);
        if (obj && (obj->type == OBJ_TREE || obj->type == OBJ_COMMIT))
                return 1;
        return 0;
@@ -281,14 +276,46 @@ static int disambiguate_blob_only(const unsigned char *sha1, void *cb_data_unuse
        return kind == OBJ_BLOB;
 }
 
-static int prepare_prefixes(const char *name, int len,
-                           unsigned char *bin_pfx,
-                           char *hex_pfx)
+static disambiguate_hint_fn default_disambiguate_hint;
+
+int set_disambiguate_hint_config(const char *var, const char *value)
+{
+       static const struct {
+               const char *name;
+               disambiguate_hint_fn fn;
+       } hints[] = {
+               { "none", NULL },
+               { "commit", disambiguate_commit_only },
+               { "committish", disambiguate_committish_only },
+               { "tree", disambiguate_tree_only },
+               { "treeish", disambiguate_treeish_only },
+               { "blob", disambiguate_blob_only }
+       };
+       int i;
+
+       if (!value)
+               return config_error_nonbool(var);
+
+       for (i = 0; i < ARRAY_SIZE(hints); i++) {
+               if (!strcasecmp(value, hints[i].name)) {
+                       default_disambiguate_hint = hints[i].fn;
+                       return 0;
+               }
+       }
+
+       return error("unknown hint type for '%s': %s", var, value);
+}
+
+static int init_object_disambiguation(const char *name, int len,
+                                     struct disambiguate_state *ds)
 {
        int i;
 
-       hashclr(bin_pfx);
-       memset(hex_pfx, 'x', 40);
+       if (len < MINIMUM_ABBREV || len > GIT_SHA1_HEXSZ)
+               return -1;
+
+       memset(ds, 0, sizeof(*ds));
+
        for (i = 0; i < len ;i++) {
                unsigned char c = name[i];
                unsigned char val;
@@ -302,11 +329,47 @@ static int prepare_prefixes(const char *name, int len,
                }
                else
                        return -1;
-               hex_pfx[i] = c;
+               ds->hex_pfx[i] = c;
                if (!(i & 1))
                        val <<= 4;
-               bin_pfx[i >> 1] |= val;
+               ds->bin_pfx[i >> 1] |= val;
        }
+
+       ds->len = len;
+       ds->hex_pfx[len] = '\0';
+       prepare_alt_odb();
+       return 0;
+}
+
+static int show_ambiguous_object(const unsigned char *sha1, void *data)
+{
+       const struct disambiguate_state *ds = data;
+       struct strbuf desc = STRBUF_INIT;
+       int type;
+
+       if (ds->fn && !ds->fn(sha1, ds->cb_data))
+               return 0;
+
+       type = sha1_object_info(sha1, NULL);
+       if (type == OBJ_COMMIT) {
+               struct commit *commit = lookup_commit(sha1);
+               if (commit) {
+                       struct pretty_print_context pp = {0};
+                       pp.date_mode.type = DATE_SHORT;
+                       format_commit_message(commit, " %ad - %s", &desc, &pp);
+               }
+       } else if (type == OBJ_TAG) {
+               struct tag *tag = lookup_tag(sha1);
+               if (!parse_tag(tag) && tag->tag)
+                       strbuf_addf(&desc, " %s", tag->tag);
+       }
+
+       advise("  %s %s%s",
+              find_unique_abbrev(sha1, DEFAULT_ABBREV),
+              typename(type) ? typename(type) : "unknown type",
+              desc.buf);
+
+       strbuf_release(&desc);
        return 0;
 }
 
@@ -314,19 +377,15 @@ static int get_short_sha1(const char *name, int len, unsigned char *sha1,
                          unsigned flags)
 {
        int status;
-       char hex_pfx[40];
-       unsigned char bin_pfx[20];
        struct disambiguate_state ds;
        int quietly = !!(flags & GET_SHA1_QUIETLY);
 
-       if (len < MINIMUM_ABBREV || len > 40)
-               return -1;
-       if (prepare_prefixes(name, len, bin_pfx, hex_pfx) < 0)
+       if (init_object_disambiguation(name, len, &ds) < 0)
                return -1;
 
-       prepare_alt_odb();
+       if (HAS_MULTI_BITS(flags & GET_SHA1_DISAMBIGUATORS))
+               die("BUG: multiple get_short_sha1 disambiguator flags");
 
-       memset(&ds, 0, sizeof(ds));
        if (flags & GET_SHA1_COMMIT)
                ds.fn = disambiguate_commit_only;
        else if (flags & GET_SHA1_COMMITTISH)
@@ -337,44 +396,98 @@ static int get_short_sha1(const char *name, int len, unsigned char *sha1,
                ds.fn = disambiguate_treeish_only;
        else if (flags & GET_SHA1_BLOB)
                ds.fn = disambiguate_blob_only;
+       else
+               ds.fn = default_disambiguate_hint;
 
-       find_short_object_filename(len, hex_pfx, &ds);
-       find_short_packed_object(len, bin_pfx, &ds);
+       find_short_object_filename(&ds);
+       find_short_packed_object(&ds);
        status = finish_object_disambiguation(&ds, sha1);
 
-       if (!quietly && (status == SHORT_NAME_AMBIGUOUS))
-               return error("short SHA1 %.*s is ambiguous.", len, hex_pfx);
+       if (!quietly && (status == SHORT_NAME_AMBIGUOUS)) {
+               error(_("short SHA1 %s is ambiguous"), ds.hex_pfx);
+
+               /*
+                * We may still have ambiguity if we simply saw a series of
+                * candidates that did not satisfy our hint function. In
+                * that case, we still want to show them, so disable the hint
+                * function entirely.
+                */
+               if (!ds.ambiguous)
+                       ds.fn = NULL;
+
+               advise(_("The candidates are:"));
+               for_each_abbrev(ds.hex_pfx, show_ambiguous_object, &ds);
+       }
+
        return status;
 }
 
+static int collect_ambiguous(const unsigned char *sha1, void *data)
+{
+       sha1_array_append(data, sha1);
+       return 0;
+}
+
 int for_each_abbrev(const char *prefix, each_abbrev_fn fn, void *cb_data)
 {
-       char hex_pfx[40];
-       unsigned char bin_pfx[20];
+       struct sha1_array collect = SHA1_ARRAY_INIT;
        struct disambiguate_state ds;
-       int len = strlen(prefix);
+       int ret;
 
-       if (len < MINIMUM_ABBREV || len > 40)
+       if (init_object_disambiguation(prefix, strlen(prefix), &ds) < 0)
                return -1;
-       if (prepare_prefixes(prefix, len, bin_pfx, hex_pfx) < 0)
-               return -1;
-
-       prepare_alt_odb();
 
-       memset(&ds, 0, sizeof(ds));
        ds.always_call_fn = 1;
-       ds.cb_data = cb_data;
-       ds.fn = fn;
+       ds.fn = collect_ambiguous;
+       ds.cb_data = &collect;
+       find_short_object_filename(&ds);
+       find_short_packed_object(&ds);
 
-       find_short_object_filename(len, hex_pfx, &ds);
-       find_short_packed_object(len, bin_pfx, &ds);
-       return ds.ambiguous;
+       ret = sha1_array_for_each_unique(&collect, fn, cb_data);
+       sha1_array_clear(&collect);
+       return ret;
+}
+
+/*
+ * Return the slot of the most-significant bit set in "val". There are various
+ * ways to do this quickly with fls() or __builtin_clzl(), but speed is
+ * probably not a big deal here.
+ */
+static unsigned msb(unsigned long val)
+{
+       unsigned r = 0;
+       while (val >>= 1)
+               r++;
+       return r;
 }
 
 int find_unique_abbrev_r(char *hex, const unsigned char *sha1, int len)
 {
        int status, exists;
 
+       if (len < 0) {
+               unsigned long count = approximate_object_count();
+               /*
+                * Add one because the MSB only tells us the highest bit set,
+                * not including the value of all the _other_ bits (so "15"
+                * is only one off of 2^4, but the MSB is the 3rd bit.
+                */
+               len = msb(count) + 1;
+               /*
+                * We now know we have on the order of 2^len objects, which
+                * expects a collision at 2^(len/2). But we also care about hex
+                * chars, not bits, and there are 4 bits per hex. So all
+                * together we need to divide by 2; but we also want to round
+                * odd numbers up, hence adding one before dividing.
+                */
+               len = (len + 1) / 2;
+               /*
+                * For very small repos, we stick with our regular fallback.
+                */
+               if (len < FALLBACK_DEFAULT_ABBREV)
+                       len = FALLBACK_DEFAULT_ABBREV;
+       }
+
        sha1_to_hex_r(hex, sha1);
        if (len == 40 || !len)
                return 40;
@@ -395,7 +508,10 @@ 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[bufno];
+       bufno = (bufno + 1) % ARRAY_SIZE(hexbuffer);
        find_unique_abbrev_r(hex, sha1, len);
        return hex;
 }
@@ -677,12 +793,12 @@ struct object *peel_to_type(const char *name, int namelen,
        }
 }
 
-static int peel_onion(const char *name, int len, unsigned char *sha1)
+static int peel_onion(const char *name, int len, unsigned char *sha1,
+                     unsigned lookup_flags)
 {
        unsigned char outer[20];
        const char *sp;
        unsigned int expected_type = 0;
-       unsigned lookup_flags = 0;
        struct object *o;
 
        /*
@@ -722,10 +838,11 @@ static int peel_onion(const char *name, int len, unsigned char *sha1)
        else
                return -1;
 
+       lookup_flags &= ~GET_SHA1_DISAMBIGUATORS;
        if (expected_type == OBJ_COMMIT)
-               lookup_flags = GET_SHA1_COMMITTISH;
+               lookup_flags |= GET_SHA1_COMMITTISH;
        else if (expected_type == OBJ_TREE)
-               lookup_flags = GET_SHA1_TREEISH;
+               lookup_flags |= GET_SHA1_TREEISH;
 
        if (get_sha1_1(name, sp - name - 2, outer, lookup_flags))
                return -1;
@@ -826,7 +943,7 @@ static int get_sha1_1(const char *name, int len, unsigned char *sha1, unsigned l
                return get_nth_ancestor(name, len1, sha1, num);
        }
 
-       ret = peel_onion(name, len, sha1);
+       ret = peel_onion(name, len, sha1, lookup_flags);
        if (!ret)
                return 0;
 
@@ -995,35 +1112,35 @@ static int interpret_nth_prior_checkout(const char *name, int namelen,
        return retval;
 }
 
-int get_sha1_mb(const char *name, unsigned char *sha1)
+int get_oid_mb(const char *name, struct object_id *oid)
 {
        struct commit *one, *two;
        struct commit_list *mbs;
-       unsigned char sha1_tmp[20];
+       struct object_id oid_tmp;
        const char *dots;
        int st;
 
        dots = strstr(name, "...");
        if (!dots)
-               return get_sha1(name, sha1);
+               return get_oid(name, oid);
        if (dots == name)
-               st = get_sha1("HEAD", sha1_tmp);
+               st = get_oid("HEAD", &oid_tmp);
        else {
                struct strbuf sb;
                strbuf_init(&sb, dots - name);
                strbuf_add(&sb, name, dots - name);
-               st = get_sha1_committish(sb.buf, sha1_tmp);
+               st = get_sha1_committish(sb.buf, oid_tmp.hash);
                strbuf_release(&sb);
        }
        if (st)
                return st;
-       one = lookup_commit_reference_gently(sha1_tmp, 0);
+       one = lookup_commit_reference_gently(oid_tmp.hash, 0);
        if (!one)
                return -1;
 
-       if (get_sha1_committish(dots[3] ? (dots + 3) : "HEAD", sha1_tmp))
+       if (get_sha1_committish(dots[3] ? (dots + 3) : "HEAD", oid_tmp.hash))
                return -1;
-       two = lookup_commit_reference_gently(sha1_tmp, 0);
+       two = lookup_commit_reference_gently(oid_tmp.hash, 0);
        if (!two)
                return -1;
        mbs = get_merge_bases(one, two);
@@ -1031,7 +1148,7 @@ int get_sha1_mb(const char *name, unsigned char *sha1)
                st = -1;
        else {
                st = 0;
-               hashcpy(sha1, mbs->item->object.oid.hash);
+               oidcpy(oid, &mbs->item->object.oid);
        }
        free_commit_list(mbs);
        return st;
@@ -1382,6 +1499,9 @@ static int get_sha1_with_context_1(const char *name,
        const char *cp;
        int only_to_die = flags & GET_SHA1_ONLY_TO_DIE;
 
+       if (only_to_die)
+               flags |= GET_SHA1_QUIETLY;
+
        memset(oc, 0, sizeof(*oc));
        oc->mode = S_IFINVALID;
        ret = get_sha1_1(name, namelen, sha1, flags);
@@ -1435,7 +1555,7 @@ static int get_sha1_with_context_1(const char *name,
                            memcmp(ce->name, cp, namelen))
                                break;
                        if (ce_stage(ce) == stage) {
-                               hashcpy(sha1, ce->sha1);
+                               hashcpy(sha1, ce->oid.hash);
                                oc->mode = ce->ce_mode;
                                free(new_path);
                                return 0;
@@ -1458,7 +1578,12 @@ static int get_sha1_with_context_1(const char *name,
        if (*cp == ':') {
                unsigned char tree_sha1[20];
                int len = cp - name;
-               if (!get_sha1_1(name, len, tree_sha1, GET_SHA1_TREEISH)) {
+               unsigned sub_flags = flags;
+
+               sub_flags &= ~GET_SHA1_DISAMBIGUATORS;
+               sub_flags |= GET_SHA1_TREEISH;
+
+               if (!get_sha1_1(name, len, tree_sha1, sub_flags)) {
                        const char *filename = cp+1;
                        char *new_filename = NULL;