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-rw-r--r--tree-walk.c452
1 files changed, 452 insertions, 0 deletions
diff --git a/tree-walk.c b/tree-walk.c
new file mode 100644
index 0000000..67a9a0c
--- /dev/null
+++ b/tree-walk.c
@@ -0,0 +1,452 @@
+#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;
+
+ if (*str == ' ')
+ return NULL;
+
+ 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 char *buf, unsigned long size)
+{
+ const char *path;
+ unsigned int mode, len;
+
+ if (size < 24 || buf[size - 21])
+ die("corrupt tree file");
+
+ path = get_mode(buf, &mode);
+ if (!path || !*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 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 setup_traverse_info(struct traverse_info *info, const char *base)
+{
+ int pathlen = strlen(base);
+ static struct traverse_info dummy;
+
+ memset(info, 0, sizeof(*info));
+ if (pathlen && base[pathlen-1] == '/')
+ pathlen--;
+ info->pathlen = pathlen ? pathlen + 1 : 0;
+ info->name.path = base;
+ info->name.sha1 = (void *)(base + pathlen + 1);
+ if (pathlen)
+ info->prev = &dummy;
+}
+
+char *make_traverse_path(char *path, const struct traverse_info *info, const struct name_entry *n)
+{
+ int len = tree_entry_len(n->path, n->sha1);
+ int pathlen = info->pathlen;
+
+ path[pathlen + len] = 0;
+ for (;;) {
+ memcpy(path + pathlen, n->path, len);
+ if (!pathlen)
+ break;
+ path[--pathlen] = '/';
+ n = &info->name;
+ len = tree_entry_len(n->path, n->sha1);
+ info = info->prev;
+ pathlen -= len;
+ }
+ return path;
+}
+
+struct tree_desc_skip {
+ struct tree_desc_skip *prev;
+ const void *ptr;
+};
+
+struct tree_desc_x {
+ struct tree_desc d;
+ struct tree_desc_skip *skip;
+};
+
+static int name_compare(const char *a, int a_len,
+ const char *b, int b_len)
+{
+ int len = (a_len < b_len) ? a_len : b_len;
+ int cmp = memcmp(a, b, len);
+ if (cmp)
+ return cmp;
+ return (a_len - b_len);
+}
+
+static int check_entry_match(const char *a, int a_len, const char *b, int b_len)
+{
+ /*
+ * The caller wants to pick *a* from a tree or nothing.
+ * We are looking at *b* in a tree.
+ *
+ * (0) If a and b are the same name, we are trivially happy.
+ *
+ * There are three possibilities where *a* could be hiding
+ * behind *b*.
+ *
+ * (1) *a* == "t", *b* == "ab" i.e. *b* sorts earlier than *a* no
+ * matter what.
+ * (2) *a* == "t", *b* == "t-2" and "t" is a subtree in the tree;
+ * (3) *a* == "t-2", *b* == "t" and "t-2" is a blob in the tree.
+ *
+ * Otherwise we know *a* won't appear in the tree without
+ * scanning further.
+ */
+
+ int cmp = name_compare(a, a_len, b, b_len);
+
+ /* Most common case first -- reading sync'd trees */
+ if (!cmp)
+ return cmp;
+
+ if (0 < cmp) {
+ /* a comes after b; it does not matter if it is case (3)
+ if (b_len < a_len && !memcmp(a, b, b_len) && a[b_len] < '/')
+ return 1;
+ */
+ return 1; /* keep looking */
+ }
+
+ /* b comes after a; are we looking at case (2)? */
+ if (a_len < b_len && !memcmp(a, b, a_len) && b[a_len] < '/')
+ return 1; /* keep looking */
+
+ return -1; /* a cannot appear in the tree */
+}
+
+/*
+ * From the extended tree_desc, extract the first name entry, while
+ * paying attention to the candidate "first" name. Most importantly,
+ * when looking for an entry, if there are entries that sorts earlier
+ * in the tree object representation than that name, skip them and
+ * process the named entry first. We will remember that we haven't
+ * processed the first entry yet, and in the later call skip the
+ * entry we processed early when update_extended_entry() is called.
+ *
+ * E.g. if the underlying tree object has these entries:
+ *
+ * blob "t-1"
+ * blob "t-2"
+ * tree "t"
+ * blob "t=1"
+ *
+ * and the "first" asks for "t", remember that we still need to
+ * process "t-1" and "t-2" but extract "t". After processing the
+ * entry "t" from this call, the caller will let us know by calling
+ * update_extended_entry() that we can remember "t" has been processed
+ * already.
+ */
+
+static void extended_entry_extract(struct tree_desc_x *t,
+ struct name_entry *a,
+ const char *first,
+ int first_len)
+{
+ const char *path;
+ int len;
+ struct tree_desc probe;
+ struct tree_desc_skip *skip;
+
+ /*
+ * Extract the first entry from the tree_desc, but skip the
+ * ones that we already returned in earlier rounds.
+ */
+ while (1) {
+ if (!t->d.size) {
+ entry_clear(a);
+ break; /* not found */
+ }
+ entry_extract(&t->d, a);
+ for (skip = t->skip; skip; skip = skip->prev)
+ if (a->path == skip->ptr)
+ break; /* found */
+ if (!skip)
+ break;
+ /* We have processed this entry already. */
+ update_tree_entry(&t->d);
+ }
+
+ if (!first || !a->path)
+ return;
+
+ /*
+ * The caller wants "first" from this tree, or nothing.
+ */
+ path = a->path;
+ len = tree_entry_len(a->path, a->sha1);
+ switch (check_entry_match(first, first_len, path, len)) {
+ case -1:
+ entry_clear(a);
+ case 0:
+ return;
+ default:
+ break;
+ }
+
+ /*
+ * We need to look-ahead -- we suspect that a subtree whose
+ * name is "first" may be hiding behind the current entry "path".
+ */
+ probe = t->d;
+ while (probe.size) {
+ entry_extract(&probe, a);
+ path = a->path;
+ len = tree_entry_len(a->path, a->sha1);
+ switch (check_entry_match(first, first_len, path, len)) {
+ case -1:
+ entry_clear(a);
+ case 0:
+ return;
+ default:
+ update_tree_entry(&probe);
+ break;
+ }
+ /* keep looking */
+ }
+ entry_clear(a);
+}
+
+static void update_extended_entry(struct tree_desc_x *t, struct name_entry *a)
+{
+ if (t->d.entry.path == a->path) {
+ update_tree_entry(&t->d);
+ } else {
+ /* we have returned this entry early */
+ struct tree_desc_skip *skip = xmalloc(sizeof(*skip));
+ skip->ptr = a->path;
+ skip->prev = t->skip;
+ t->skip = skip;
+ }
+}
+
+static void free_extended_entry(struct tree_desc_x *t)
+{
+ struct tree_desc_skip *p, *s;
+
+ for (s = t->skip; s; s = p) {
+ p = s->prev;
+ free(s);
+ }
+}
+
+int traverse_trees(int n, struct tree_desc *t, struct traverse_info *info)
+{
+ int ret = 0;
+ struct name_entry *entry = xmalloc(n*sizeof(*entry));
+ int i;
+ struct tree_desc_x *tx = xcalloc(n, sizeof(*tx));
+
+ for (i = 0; i < n; i++)
+ tx[i].d = t[i];
+
+ for (;;) {
+ unsigned long mask, dirmask;
+ const char *first = NULL;
+ int first_len = 0;
+ struct name_entry *e;
+ int len;
+
+ for (i = 0; i < n; i++) {
+ e = entry + i;
+ extended_entry_extract(tx + i, e, NULL, 0);
+ }
+
+ /*
+ * A tree may have "t-2" at the current location even
+ * though it may have "t" that is a subtree behind it,
+ * and another tree may return "t". We want to grab
+ * all "t" from all trees to match in such a case.
+ */
+ for (i = 0; i < n; i++) {
+ e = entry + i;
+ if (!e->path)
+ continue;
+ len = tree_entry_len(e->path, e->sha1);
+ if (!first) {
+ first = e->path;
+ first_len = len;
+ continue;
+ }
+ if (name_compare(e->path, len, first, first_len) < 0) {
+ first = e->path;
+ first_len = len;
+ }
+ }
+
+ if (first) {
+ for (i = 0; i < n; i++) {
+ e = entry + i;
+ extended_entry_extract(tx + i, e, first, first_len);
+ /* Cull the ones that are not the earliest */
+ if (!e->path)
+ continue;
+ len = tree_entry_len(e->path, e->sha1);
+ if (name_compare(e->path, len, first, first_len))
+ entry_clear(e);
+ }
+ }
+
+ /* Now we have in entry[i] the earliest name from the trees */
+ mask = 0;
+ dirmask = 0;
+ for (i = 0; i < n; i++) {
+ if (!entry[i].path)
+ continue;
+ mask |= 1ul << i;
+ if (S_ISDIR(entry[i].mode))
+ dirmask |= 1ul << i;
+ }
+ if (!mask)
+ break;
+ ret = info->fn(n, mask, dirmask, entry, info);
+ if (ret < 0)
+ break;
+ mask &= ret;
+ ret = 0;
+ for (i = 0; i < n; i++)
+ if (mask & (1ul << i))
+ update_extended_entry(tx + i, entry + i);
+ }
+ free(entry);
+ for (i = 0; i < n; i++)
+ free_extended_entry(tx + i);
+ free(tx);
+ return ret;
+}
+
+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);
+ free(tree);
+ return 0;
+ }
+
+ init_tree_desc(&t, tree, size);
+ retval = find_tree_entry(&t, name, sha1, mode);
+ free(tree);
+ return retval;
+}
generated by cgit v0.10.2-6-g49f6 at 2024-04-25 12:41:27 (GMT)