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-rw-r--r--sha1_name.c228
1 files changed, 228 insertions, 0 deletions
diff --git a/sha1_name.c b/sha1_name.c
new file mode 100644
index 0000000..df3ba2d
--- /dev/null
+++ b/sha1_name.c
@@ -0,0 +1,228 @@
+#include "cache.h"
+#include "commit.h"
+
+static int find_short_object_filename(int len, const char *name, unsigned char *sha1)
+{
+ static char dirname[PATH_MAX];
+ char hex[40];
+ DIR *dir;
+ int found;
+
+ snprintf(dirname, sizeof(dirname), "%s/%.2s", get_object_directory(), name);
+ dir = opendir(dirname);
+ sprintf(hex, "%.2s", name);
+ found = 0;
+ if (dir) {
+ struct dirent *de;
+ while ((de = readdir(dir)) != NULL) {
+ if (strlen(de->d_name) != 38)
+ continue;
+ if (memcmp(de->d_name, name + 2, len-2))
+ continue;
+ memcpy(hex + 2, de->d_name, 38);
+ if (++found > 1)
+ break;
+ }
+ closedir(dir);
+ }
+ if (found == 1)
+ return get_sha1_hex(hex, sha1) == 0;
+ return 0;
+}
+
+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;
+
+ prepare_packed_git();
+ for (p = packed_git; p; 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)) {
+ memcpy(sha1, now, 20);
+ return 1;
+ }
+ }
+ }
+ }
+ return 0;
+}
+
+static int get_short_sha1(const char *name, unsigned char *sha1)
+{
+ int i;
+ char canonical[40];
+ unsigned char res[20];
+
+ memset(res, 0, 20);
+ memset(canonical, 'x', 40);
+ for (i = 0;;i++) {
+ unsigned char c = name[i];
+ unsigned char val;
+ if (!c || i > 40)
+ break;
+ 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;
+ }
+ if (i < 4)
+ return -1;
+ if (find_short_object_filename(i, canonical, sha1))
+ return 0;
+ if (find_short_packed_object(i, res, sha1))
+ return 0;
+ return -1;
+}
+
+static int get_sha1_file(const char *path, unsigned char *result)
+{
+ char buffer[60];
+ int fd = open(path, O_RDONLY);
+ int len;
+
+ if (fd < 0)
+ return -1;
+ len = read(fd, buffer, sizeof(buffer));
+ close(fd);
+ if (len < 40)
+ return -1;
+ return get_sha1_hex(buffer, result);
+}
+
+static int get_sha1_basic(const char *str, int len, unsigned char *sha1)
+{
+ static const char *prefix[] = {
+ "",
+ "refs",
+ "refs/tags",
+ "refs/heads",
+ "refs/snap",
+ NULL
+ };
+ const char **p;
+
+ if (!get_sha1_hex(str, sha1))
+ return 0;
+
+ for (p = prefix; *p; p++) {
+ char *pathname = git_path("%s/%.*s", *p, len, str);
+ if (!get_sha1_file(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_sha1_1(const char *name, int len, unsigned char *sha1)
+{
+ int parent, ret;
+
+ /* 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;
+ else
+ parent = -1;
+
+ if (0 <= parent) {
+ ret = get_parent(name, len-1, sha1, parent);
+ if (!ret)
+ return 0;
+ }
+ ret = get_sha1_basic(name, len, sha1);
+ if (!ret)
+ return 0;
+ return get_short_sha1(name, sha1);
+}
+
+/*
+ * 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)
+{
+ return get_sha1_1(name, strlen(name), sha1);
+}