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git-commit-vandalism/sha1_name.c
Junio C Hamano 5385f52da8 Introduce notation "ref^{type}". 
Existing "tagname^0" notation means "dereference tag zero or more
times until you cannot dereference it anymore, and make sure it is a
commit -- otherwise barf".  But tags do not necessarily reference
commit objects.

This commit introduces a bit more generalized notation, "ref^{type}".
Existing "ref^0" is a shorthand for "ref^{commit}".  If the type
is empty, it just dereferences tags until it hits a non-tag object.

With this, "git-rev-parse --verify 'junio-gpg-pub^{}'" shows the blob
object name -- there is no need to manually read the tag object and
find out the object name anymore.

"git-rev-parse --verify 'HEAD^{tree}'" can be used to find out the
tree object name of the HEAD commit.

Signed-off-by: Junio C Hamano <junkio@cox.net>
2005-10-15 11:23:40 -07:00

416 lines
9.1 KiB
C
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#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)
{
struct alternate_object_database *alt;
char hex[40];
int found = 0;
static struct alternate_object_database *fakeent;
if (!fakeent) {
const char *objdir = get_object_directory();
int objdir_len = strlen(objdir);
int entlen = objdir_len + 43;
fakeent = xmalloc(sizeof(*fakeent) + entlen);
memcpy(fakeent->base, objdir, objdir_len);
fakeent->name = fakeent->base + objdir_len + 1;
fakeent->name[-1] = '/';
}
fakeent->next = alt_odb_list;
sprintf(hex, "%.2s", name);
for (alt = fakeent; alt && found < 2; alt = alt->next) {
struct dirent *de;
DIR *dir;
sprintf(alt->name, "%.2s/", name);
dir = opendir(alt->base);
if (!dir)
continue;
while ((de = readdir(dir)) != NULL) {
if (strlen(de->d_name) != 38)
continue;
if (memcmp(de->d_name, name + 2, len - 2))
continue;
if (!found) {
memcpy(hex + 2, de->d_name, 38);
found++;
}
else if (memcmp(hex + 2, de->d_name, 38)) {
found = 2;
break;
}
}
closedir(dir);
}
if (found == 1)
return get_sha1_hex(hex, sha1) == 0;
return found;
}
static int match_sha(unsigned len, const unsigned char *a, const unsigned char *b)
{
do {
if (*a != *b)
return 0;
a++;
b++;
len -= 2;
} while (len > 1);
if (len)
if ((*a ^ *b) & 0xf0)
return 0;
return 1;
}
static int find_short_packed_object(int len, const unsigned char *match, unsigned char *sha1)
{
struct packed_git *p;
unsigned char found_sha1[20];
int found = 0;
prepare_packed_git();
for (p = packed_git; p && found < 2; p = p->next) {
unsigned num = num_packed_objects(p);
unsigned first = 0, last = num;
while (first < last) {
unsigned mid = (first + last) / 2;
unsigned char now[20];
int cmp;
nth_packed_object_sha1(p, mid, now);
cmp = memcmp(match, now, 20);
if (!cmp) {
first = mid;
break;
}
if (cmp > 0) {
first = mid+1;
continue;
}
last = mid;
}
if (first < num) {
unsigned char now[20], next[20];
nth_packed_object_sha1(p, first, now);
if (match_sha(len, match, now)) {
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 {
/* not even unique within this pack */
found = 2;
break;
}
}
}
}
if (found == 1)
memcpy(sha1, found_sha1, 20);
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)
{
int has_unpacked, has_packed;
unsigned char unpacked_sha1[20], packed_sha1[20];
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 SHORT_NAME_NOT_FOUND;
if (1 < has_unpacked || 1 < has_packed)
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 -2;
memcpy(sha1, packed_sha1, 20);
return 0;
}
static int get_short_sha1(const char *name, int len, unsigned char *sha1,
int quietly)
{
int i, status;
char canonical[40];
unsigned char res[20];
if (len < 4)
return -1;
memset(res, 0, 20);
memset(canonical, 'x', 40);
for (i = 0; i < len ;i++) {
unsigned char c = name[i];
unsigned char val;
if (c >= '0' && c <= '9')
val = c - '0';
else if (c >= 'a' && c <= 'f')
val = c - 'a' + 10;
else if (c >= 'A' && c <='F') {
val = c - 'A' + 10;
c -= 'A' - 'a';
}
else
return -1;
canonical[i] = c;
if (!(i & 1))
val <<= 4;
res[i >> 1] |= val;
}
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 get_sha1_basic(const char *str, int len, unsigned char *sha1)
{
static const char *prefix[] = {
"",
"refs",
"refs/tags",
"refs/heads",
NULL
};
const char **p;
if (len == 40 && !get_sha1_hex(str, sha1))
return 0;
for (p = prefix; *p; p++) {
char *pathname = git_path("%s/%.*s", *p, len, str);
if (!read_ref(pathname, sha1))
return 0;
}
return -1;
}
static int get_sha1_1(const char *name, int len, unsigned char *sha1);
static int get_parent(const char *name, int len,
unsigned char *result, int idx)
{
unsigned char sha1[20];
int ret = get_sha1_1(name, len, sha1);
struct commit *commit;
struct commit_list *p;
if (ret)
return ret;
commit = lookup_commit_reference(sha1);
if (!commit)
return -1;
if (parse_commit(commit))
return -1;
if (!idx) {
memcpy(result, commit->object.sha1, 20);
return 0;
}
p = commit->parents;
while (p) {
if (!--idx) {
memcpy(result, p->item->object.sha1, 20);
return 0;
}
p = p->next;
}
return -1;
}
static int get_nth_ancestor(const char *name, int len,
unsigned char *result, int generation)
{
unsigned char sha1[20];
int ret = get_sha1_1(name, len, sha1);
if (ret)
return ret;
while (generation--) {
struct commit *commit = lookup_commit_reference(sha1);
if (!commit || parse_commit(commit) || !commit->parents)
return -1;
memcpy(sha1, commit->parents->item->object.sha1, 20);
}
memcpy(result, sha1, 20);
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);
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)
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;
const char *cp;
/* foo^[0-9] or foo^ (== foo^1); we do not do more than 9 parents. */
if (len > 2 && name[len-2] == '^' &&
name[len-1] >= '0' && name[len-1] <= '9') {
parent = name[len-1] - '0';
len -= 2;
}
else if (len > 1 && name[len-1] == '^') {
parent = 1;
len--;
} else
parent = -1;
if (parent >= 0)
return get_parent(name, len, sha1, parent);
/* "name~3" is "name^^^",
* "name~12" is "name^^^^^^^^^^^^", and
* "name~" and "name~0" are name -- not "name^0"!
*/
parent = 0;
for (cp = name + len - 1; name <= cp; cp--) {
int ch = *cp;
if ('0' <= ch && ch <= '9')
continue;
if (ch != '~')
parent = -1;
break;
}
if (!parent && *cp == '~') {
int len1 = cp - name;
cp++;
while (cp < name + len)
parent = parent * 10 + *cp++ - '0';
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, 0);
}
/*
* This is like "get_sha1_basic()", except it allows "sha1 expressions",
* notably "xyz^" for "parent of xyz"
*/
int get_sha1(const char *name, unsigned char *sha1)
{
prepare_alt_odb();
return get_sha1_1(name, strlen(name), sha1);
}
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