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-rw-r--r--tree-walk.c209
1 files changed, 209 insertions, 0 deletions
diff --git a/tree-walk.c b/tree-walk.c
new file mode 100644
index 0000000..cbb24eb
--- /dev/null
+++ b/tree-walk.c
@@ -0,0 +1,209 @@
+#include "cache.h"
+#include "tree-walk.h"
+#include "tree.h"
+
+static const char *get_mode(const char *str, unsigned int *modep)
+{
+ unsigned char c;
+ unsigned int mode = 0;
+
+ while ((c = *str++) != ' ') {
+ if (c < '0' || c > '7')
+ return NULL;
+ mode = (mode << 3) + (c - '0');
+ }
+ *modep = mode;
+ return str;
+}
+
+static void decode_tree_entry(struct tree_desc *desc, const void *buf, unsigned long size)
+{
+ const char *path;
+ unsigned int mode, len;
+
+ path = get_mode(buf, &mode);
+ if (!path)
+ die("corrupt tree file");
+ len = strlen(path) + 1;
+
+ /* Initialize the descriptor entry */
+ desc->entry.path = path;
+ desc->entry.mode = mode;
+ desc->entry.sha1 = (const unsigned char *)(path + len);
+}
+
+void init_tree_desc(struct tree_desc *desc, const void *buffer, unsigned long size)
+{
+ desc->buffer = buffer;
+ desc->size = size;
+ if (size)
+ decode_tree_entry(desc, buffer, size);
+}
+
+void *fill_tree_descriptor(struct tree_desc *desc, const unsigned char *sha1)
+{
+ unsigned long size = 0;
+ void *buf = NULL;
+
+ if (sha1) {
+ buf = read_object_with_reference(sha1, tree_type, &size, NULL);
+ if (!buf)
+ die("unable to read tree %s", sha1_to_hex(sha1));
+ }
+ init_tree_desc(desc, buf, size);
+ return buf;
+}
+
+static int entry_compare(struct name_entry *a, struct name_entry *b)
+{
+ return base_name_compare(
+ a->path, tree_entry_len(a->path, a->sha1), a->mode,
+ b->path, tree_entry_len(b->path, b->sha1), b->mode);
+}
+
+static void entry_clear(struct name_entry *a)
+{
+ memset(a, 0, sizeof(*a));
+}
+
+static void entry_extract(struct tree_desc *t, struct name_entry *a)
+{
+ *a = t->entry;
+}
+
+void update_tree_entry(struct tree_desc *desc)
+{
+ const void *buf = desc->buffer;
+ const unsigned char *end = desc->entry.sha1 + 20;
+ unsigned long size = desc->size;
+ unsigned long len = end - (const unsigned char *)buf;
+
+ if (size < len)
+ die("corrupt tree file");
+ buf = end;
+ size -= len;
+ desc->buffer = buf;
+ desc->size = size;
+ if (size)
+ decode_tree_entry(desc, buf, size);
+}
+
+int tree_entry(struct tree_desc *desc, struct name_entry *entry)
+{
+ if (!desc->size)
+ return 0;
+
+ *entry = desc->entry;
+ update_tree_entry(desc);
+ return 1;
+}
+
+void traverse_trees(int n, struct tree_desc *t, const char *base, traverse_callback_t callback)
+{
+ struct name_entry *entry = xmalloc(n*sizeof(*entry));
+
+ for (;;) {
+ unsigned long mask = 0;
+ int i, last;
+
+ last = -1;
+ for (i = 0; i < n; i++) {
+ if (!t[i].size)
+ continue;
+ entry_extract(t+i, entry+i);
+ if (last >= 0) {
+ int cmp = entry_compare(entry+i, entry+last);
+
+ /*
+ * Is the new name bigger than the old one?
+ * Ignore it
+ */
+ if (cmp > 0)
+ continue;
+ /*
+ * Is the new name smaller than the old one?
+ * Ignore all old ones
+ */
+ if (cmp < 0)
+ mask = 0;
+ }
+ mask |= 1ul << i;
+ last = i;
+ }
+ if (!mask)
+ break;
+
+ /*
+ * Update the tree entries we've walked, and clear
+ * all the unused name-entries.
+ */
+ for (i = 0; i < n; i++) {
+ if (mask & (1ul << i)) {
+ update_tree_entry(t+i);
+ continue;
+ }
+ entry_clear(entry + i);
+ }
+ callback(n, mask, entry, base);
+ }
+ free(entry);
+}
+
+static int find_tree_entry(struct tree_desc *t, const char *name, unsigned char *result, unsigned *mode)
+{
+ int namelen = strlen(name);
+ while (t->size) {
+ const char *entry;
+ const unsigned char *sha1;
+ int entrylen, cmp;
+
+ sha1 = tree_entry_extract(t, &entry, mode);
+ update_tree_entry(t);
+ entrylen = tree_entry_len(entry, sha1);
+ if (entrylen > namelen)
+ continue;
+ cmp = memcmp(name, entry, entrylen);
+ if (cmp > 0)
+ continue;
+ if (cmp < 0)
+ break;
+ if (entrylen == namelen) {
+ hashcpy(result, sha1);
+ return 0;
+ }
+ if (name[entrylen] != '/')
+ continue;
+ if (!S_ISDIR(*mode))
+ break;
+ if (++entrylen == namelen) {
+ hashcpy(result, sha1);
+ return 0;
+ }
+ return get_tree_entry(sha1, name + entrylen, result, mode);
+ }
+ return -1;
+}
+
+int get_tree_entry(const unsigned char *tree_sha1, const char *name, unsigned char *sha1, unsigned *mode)
+{
+ int retval;
+ void *tree;
+ unsigned long size;
+ struct tree_desc t;
+ unsigned char root[20];
+
+ tree = read_object_with_reference(tree_sha1, tree_type, &size, root);
+ if (!tree)
+ return -1;
+
+ if (name[0] == '\0') {
+ hashcpy(sha1, root);
+ return 0;
+ }
+
+ init_tree_desc(&t, tree, size);
+ retval = find_tree_entry(&t, name, sha1, mode);
+ free(tree);
+ return retval;
+}
+