452 lines
10 KiB
C
452 lines
10 KiB
C
#include "cache.h"
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#include "tree-walk.h"
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#include "tree.h"
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static const char *get_mode(const char *str, unsigned int *modep)
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{
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unsigned char c;
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unsigned int mode = 0;
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if (*str == ' ')
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return NULL;
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while ((c = *str++) != ' ') {
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if (c < '0' || c > '7')
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return NULL;
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mode = (mode << 3) + (c - '0');
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}
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*modep = mode;
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return str;
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}
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static void decode_tree_entry(struct tree_desc *desc, const char *buf, unsigned long size)
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{
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const char *path;
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unsigned int mode, len;
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if (size < 24 || buf[size - 21])
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die("corrupt tree file");
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path = get_mode(buf, &mode);
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if (!path || !*path)
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die("corrupt tree file");
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len = strlen(path) + 1;
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/* Initialize the descriptor entry */
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desc->entry.path = path;
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desc->entry.mode = mode;
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desc->entry.sha1 = (const unsigned char *)(path + len);
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}
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void init_tree_desc(struct tree_desc *desc, const void *buffer, unsigned long size)
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{
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desc->buffer = buffer;
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desc->size = size;
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if (size)
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decode_tree_entry(desc, buffer, size);
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}
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void *fill_tree_descriptor(struct tree_desc *desc, const unsigned char *sha1)
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{
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unsigned long size = 0;
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void *buf = NULL;
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if (sha1) {
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buf = read_object_with_reference(sha1, tree_type, &size, NULL);
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if (!buf)
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die("unable to read tree %s", sha1_to_hex(sha1));
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}
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init_tree_desc(desc, buf, size);
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return buf;
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}
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static void entry_clear(struct name_entry *a)
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{
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memset(a, 0, sizeof(*a));
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}
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static void entry_extract(struct tree_desc *t, struct name_entry *a)
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{
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*a = t->entry;
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}
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void update_tree_entry(struct tree_desc *desc)
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{
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const void *buf = desc->buffer;
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const unsigned char *end = desc->entry.sha1 + 20;
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unsigned long size = desc->size;
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unsigned long len = end - (const unsigned char *)buf;
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if (size < len)
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die("corrupt tree file");
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buf = end;
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size -= len;
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desc->buffer = buf;
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desc->size = size;
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if (size)
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decode_tree_entry(desc, buf, size);
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}
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int tree_entry(struct tree_desc *desc, struct name_entry *entry)
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{
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if (!desc->size)
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return 0;
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*entry = desc->entry;
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update_tree_entry(desc);
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return 1;
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}
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void setup_traverse_info(struct traverse_info *info, const char *base)
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{
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int pathlen = strlen(base);
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static struct traverse_info dummy;
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memset(info, 0, sizeof(*info));
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if (pathlen && base[pathlen-1] == '/')
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pathlen--;
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info->pathlen = pathlen ? pathlen + 1 : 0;
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info->name.path = base;
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info->name.sha1 = (void *)(base + pathlen + 1);
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if (pathlen)
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info->prev = &dummy;
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}
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char *make_traverse_path(char *path, const struct traverse_info *info, const struct name_entry *n)
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{
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int len = tree_entry_len(n->path, n->sha1);
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int pathlen = info->pathlen;
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path[pathlen + len] = 0;
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for (;;) {
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memcpy(path + pathlen, n->path, len);
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if (!pathlen)
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break;
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path[--pathlen] = '/';
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n = &info->name;
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len = tree_entry_len(n->path, n->sha1);
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info = info->prev;
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pathlen -= len;
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}
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return path;
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}
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struct tree_desc_skip {
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struct tree_desc_skip *prev;
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const void *ptr;
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};
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struct tree_desc_x {
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struct tree_desc d;
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struct tree_desc_skip *skip;
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};
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static int name_compare(const char *a, int a_len,
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const char *b, int b_len)
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{
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int len = (a_len < b_len) ? a_len : b_len;
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int cmp = memcmp(a, b, len);
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if (cmp)
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return cmp;
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return (a_len - b_len);
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}
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static int check_entry_match(const char *a, int a_len, const char *b, int b_len)
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{
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/*
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* The caller wants to pick *a* from a tree or nothing.
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* We are looking at *b* in a tree.
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*
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* (0) If a and b are the same name, we are trivially happy.
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*
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* There are three possibilities where *a* could be hiding
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* behind *b*.
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*
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* (1) *a* == "t", *b* == "ab" i.e. *b* sorts earlier than *a* no
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* matter what.
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* (2) *a* == "t", *b* == "t-2" and "t" is a subtree in the tree;
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* (3) *a* == "t-2", *b* == "t" and "t-2" is a blob in the tree.
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*
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* Otherwise we know *a* won't appear in the tree without
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* scanning further.
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*/
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int cmp = name_compare(a, a_len, b, b_len);
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/* Most common case first -- reading sync'd trees */
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if (!cmp)
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return cmp;
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if (0 < cmp) {
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/* a comes after b; it does not matter if it is case (3)
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if (b_len < a_len && !memcmp(a, b, b_len) && a[b_len] < '/')
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return 1;
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*/
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return 1; /* keep looking */
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}
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/* b comes after a; are we looking at case (2)? */
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if (a_len < b_len && !memcmp(a, b, a_len) && b[a_len] < '/')
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return 1; /* keep looking */
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return -1; /* a cannot appear in the tree */
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}
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/*
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* From the extended tree_desc, extract the first name entry, while
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* paying attention to the candidate "first" name. Most importantly,
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* when looking for an entry, if there are entries that sorts earlier
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* in the tree object representation than that name, skip them and
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* process the named entry first. We will remember that we haven't
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* processed the first entry yet, and in the later call skip the
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* entry we processed early when update_extended_entry() is called.
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*
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* E.g. if the underlying tree object has these entries:
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*
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* blob "t-1"
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* blob "t-2"
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* tree "t"
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* blob "t=1"
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*
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* and the "first" asks for "t", remember that we still need to
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* process "t-1" and "t-2" but extract "t". After processing the
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* entry "t" from this call, the caller will let us know by calling
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* update_extended_entry() that we can remember "t" has been processed
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* already.
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*/
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static void extended_entry_extract(struct tree_desc_x *t,
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struct name_entry *a,
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const char *first,
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int first_len)
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{
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const char *path;
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int len;
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struct tree_desc probe;
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struct tree_desc_skip *skip;
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/*
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* Extract the first entry from the tree_desc, but skip the
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* ones that we already returned in earlier rounds.
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*/
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while (1) {
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if (!t->d.size) {
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entry_clear(a);
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break; /* not found */
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}
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entry_extract(&t->d, a);
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for (skip = t->skip; skip; skip = skip->prev)
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if (a->path == skip->ptr)
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break; /* found */
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if (!skip)
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break;
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/* We have processed this entry already. */
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update_tree_entry(&t->d);
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}
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if (!first || !a->path)
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return;
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/*
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* The caller wants "first" from this tree, or nothing.
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*/
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path = a->path;
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len = tree_entry_len(a->path, a->sha1);
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switch (check_entry_match(first, first_len, path, len)) {
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case -1:
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entry_clear(a);
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case 0:
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return;
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default:
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break;
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}
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/*
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* We need to look-ahead -- we suspect that a subtree whose
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* name is "first" may be hiding behind the current entry "path".
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*/
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probe = t->d;
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while (probe.size) {
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entry_extract(&probe, a);
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path = a->path;
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len = tree_entry_len(a->path, a->sha1);
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switch (check_entry_match(first, first_len, path, len)) {
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case -1:
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entry_clear(a);
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case 0:
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return;
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default:
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update_tree_entry(&probe);
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break;
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}
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/* keep looking */
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}
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entry_clear(a);
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}
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static void update_extended_entry(struct tree_desc_x *t, struct name_entry *a)
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{
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if (t->d.entry.path == a->path) {
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update_tree_entry(&t->d);
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} else {
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/* we have returned this entry early */
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struct tree_desc_skip *skip = xmalloc(sizeof(*skip));
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skip->ptr = a->path;
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skip->prev = t->skip;
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t->skip = skip;
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}
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}
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static void free_extended_entry(struct tree_desc_x *t)
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{
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struct tree_desc_skip *p, *s;
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for (s = t->skip; s; s = p) {
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p = s->prev;
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free(s);
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}
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}
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int traverse_trees(int n, struct tree_desc *t, struct traverse_info *info)
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{
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int ret = 0;
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struct name_entry *entry = xmalloc(n*sizeof(*entry));
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int i;
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struct tree_desc_x *tx = xcalloc(n, sizeof(*tx));
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for (i = 0; i < n; i++)
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tx[i].d = t[i];
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for (;;) {
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unsigned long mask, dirmask;
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const char *first = NULL;
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int first_len = 0;
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struct name_entry *e;
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int len;
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for (i = 0; i < n; i++) {
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e = entry + i;
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extended_entry_extract(tx + i, e, NULL, 0);
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}
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/*
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* A tree may have "t-2" at the current location even
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* though it may have "t" that is a subtree behind it,
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* and another tree may return "t". We want to grab
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* all "t" from all trees to match in such a case.
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*/
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for (i = 0; i < n; i++) {
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e = entry + i;
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if (!e->path)
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continue;
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len = tree_entry_len(e->path, e->sha1);
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if (!first) {
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first = e->path;
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first_len = len;
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continue;
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}
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if (name_compare(e->path, len, first, first_len) < 0) {
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first = e->path;
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first_len = len;
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}
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}
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if (first) {
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for (i = 0; i < n; i++) {
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e = entry + i;
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extended_entry_extract(tx + i, e, first, first_len);
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/* Cull the ones that are not the earliest */
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if (!e->path)
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continue;
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len = tree_entry_len(e->path, e->sha1);
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if (name_compare(e->path, len, first, first_len))
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entry_clear(e);
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}
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}
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/* Now we have in entry[i] the earliest name from the trees */
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mask = 0;
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dirmask = 0;
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for (i = 0; i < n; i++) {
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if (!entry[i].path)
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continue;
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mask |= 1ul << i;
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if (S_ISDIR(entry[i].mode))
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dirmask |= 1ul << i;
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}
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if (!mask)
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break;
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ret = info->fn(n, mask, dirmask, entry, info);
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if (ret < 0)
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break;
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mask &= ret;
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ret = 0;
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for (i = 0; i < n; i++)
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if (mask & (1ul << i))
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update_extended_entry(tx + i, entry + i);
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}
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free(entry);
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for (i = 0; i < n; i++)
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free_extended_entry(tx + i);
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free(tx);
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return ret;
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}
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static int find_tree_entry(struct tree_desc *t, const char *name, unsigned char *result, unsigned *mode)
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{
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int namelen = strlen(name);
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while (t->size) {
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const char *entry;
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const unsigned char *sha1;
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int entrylen, cmp;
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sha1 = tree_entry_extract(t, &entry, mode);
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update_tree_entry(t);
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entrylen = tree_entry_len(entry, sha1);
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if (entrylen > namelen)
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continue;
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cmp = memcmp(name, entry, entrylen);
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if (cmp > 0)
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continue;
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if (cmp < 0)
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break;
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if (entrylen == namelen) {
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hashcpy(result, sha1);
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return 0;
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}
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if (name[entrylen] != '/')
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continue;
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if (!S_ISDIR(*mode))
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break;
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if (++entrylen == namelen) {
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hashcpy(result, sha1);
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return 0;
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}
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return get_tree_entry(sha1, name + entrylen, result, mode);
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}
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return -1;
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}
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int get_tree_entry(const unsigned char *tree_sha1, const char *name, unsigned char *sha1, unsigned *mode)
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{
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int retval;
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void *tree;
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unsigned long size;
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struct tree_desc t;
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unsigned char root[20];
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tree = read_object_with_reference(tree_sha1, tree_type, &size, root);
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if (!tree)
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return -1;
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if (name[0] == '\0') {
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hashcpy(sha1, root);
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return 0;
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}
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init_tree_desc(&t, tree, size);
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retval = find_tree_entry(&t, name, sha1, mode);
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free(tree);
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return retval;
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}
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