tree-walk.c

   1 #include "cache.h"
   2 #include "tree-walk.h"
   3 #include "tree.h"
   4
   5 static const char *get_mode(const char *str, unsigned int *modep)
   6 {
   7         unsigned char c;
   8         unsigned int mode = 0;
   9
  10         if (*str == ' ')
  11                 return NULL;
  12
  13         while ((c = *str++) != ' ') {
  14                 if (c < '0' || c > '7')
  15                         return NULL;
  16                 mode = (mode << 3) + (c - '0');
  17         }
  18         *modep = mode;
  19         return str;
  20 }
  21
  22 static void decode_tree_entry(struct tree_desc *desc, const char *buf, unsigned long size)
  23 {
  24         const char *path;
  25         unsigned int mode, len;
  26
  27         if (size < 24 || buf[size - 21])
  28                 die("corrupt tree file");
  29
  30         path = get_mode(buf, &mode);
  31         if (!path || !*path)
  32                 die("corrupt tree file");
  33         len = strlen(path) + 1;
  34
  35         /* Initialize the descriptor entry */
  36         desc->entry.path = path;
  37         desc->entry.mode = mode;
  38         desc->entry.sha1 = (const unsigned char *)(path + len);
  39 }
  40
  41 void init_tree_desc(struct tree_desc *desc, const void *buffer, unsigned long size)
  42 {
  43         desc->buffer = buffer;
  44         desc->size = size;
  45         if (size)
  46                 decode_tree_entry(desc, buffer, size);
  47 }
  48
  49 void *fill_tree_descriptor(struct tree_desc *desc, const unsigned char *sha1)
  50 {
  51         unsigned long size = 0;
  52         void *buf = NULL;
  53
  54         if (sha1) {
  55                 buf = read_object_with_reference(sha1, tree_type, &size, NULL);
  56                 if (!buf)
  57                         die("unable to read tree %s", sha1_to_hex(sha1));
  58         }
  59         init_tree_desc(desc, buf, size);
  60         return buf;
  61 }
  62
  63 static int entry_compare(struct name_entry *a, struct name_entry *b)
  64 {
  65         return base_name_compare(
  66                         a->path, tree_entry_len(a->path, a->sha1), a->mode,
  67                         b->path, tree_entry_len(b->path, b->sha1), b->mode);
  68 }
  69
  70 static void entry_clear(struct name_entry *a)
  71 {
  72         memset(a, 0, sizeof(*a));
  73 }
  74
  75 static void entry_extract(struct tree_desc *t, struct name_entry *a)
  76 {
  77         *a = t->entry;
  78 }
  79
  80 void update_tree_entry(struct tree_desc *desc)
  81 {
  82         const void *buf = desc->buffer;
  83         const unsigned char *end = desc->entry.sha1 + 20;
  84         unsigned long size = desc->size;
  85         unsigned long len = end - (const unsigned char *)buf;
  86
  87         if (size < len)
  88                 die("corrupt tree file");
  89         buf = end;
  90         size -= len;
  91         desc->buffer = buf;
  92         desc->size = size;
  93         if (size)
  94                 decode_tree_entry(desc, buf, size);
  95 }
  96
  97 int tree_entry(struct tree_desc *desc, struct name_entry *entry)
  98 {
  99         if (!desc->size)
 100                 return 0;
 101
 102         *entry = desc->entry;
 103         update_tree_entry(desc);
 104         return 1;
 105 }
 106
 107 void traverse_trees(int n, struct tree_desc *t, const char *base, traverse_callback_t callback)
 108 {
 109         struct name_entry *entry = xmalloc(n*sizeof(*entry));
 110
 111         for (;;) {
 112                 unsigned long mask = 0;
 113                 int i, last;
 114
 115                 last = -1;
 116                 for (i = 0; i < n; i++) {
 117                         if (!t[i].size)
 118                                 continue;
 119                         entry_extract(t+i, entry+i);
 120                         if (last >= 0) {
 121                                 int cmp = entry_compare(entry+i, entry+last);
 122
 123                                 /*
 124                                  * Is the new name bigger than the old one?
 125                                  * Ignore it
 126                                  */
 127                                 if (cmp > 0)
 128                                         continue;
 129                                 /*
 130                                  * Is the new name smaller than the old one?
 131                                  * Ignore all old ones
 132                                  */
 133                                 if (cmp < 0)
 134                                         mask = 0;
 135                         }
 136                         mask |= 1ul << i;
 137                         last = i;
 138                 }
 139                 if (!mask)
 140                         break;
 141
 142                 /*
 143                  * Update the tree entries we've walked, and clear
 144                  * all the unused name-entries.
 145                  */
 146                 for (i = 0; i < n; i++) {
 147                         if (mask & (1ul << i)) {
 148                                 update_tree_entry(t+i);
 149                                 continue;
 150                         }
 151                         entry_clear(entry + i);
 152                 }
 153                 callback(n, mask, entry, base);
 154         }
 155         free(entry);
 156 }
 157
 158 static int find_tree_entry(struct tree_desc *t, const char *name, unsigned char *result, unsigned *mode)
 159 {
 160         int namelen = strlen(name);
 161         while (t->size) {
 162                 const char *entry;
 163                 const unsigned char *sha1;
 164                 int entrylen, cmp;
 165
 166                 sha1 = tree_entry_extract(t, &entry, mode);
 167                 update_tree_entry(t);
 168                 entrylen = tree_entry_len(entry, sha1);
 169                 if (entrylen > namelen)
 170                         continue;
 171                 cmp = memcmp(name, entry, entrylen);
 172                 if (cmp > 0)
 173                         continue;
 174                 if (cmp < 0)
 175                         break;
 176                 if (entrylen == namelen) {
 177                         hashcpy(result, sha1);
 178                         return 0;
 179                 }
 180                 if (name[entrylen] != '/')
 181                         continue;
 182                 if (!S_ISDIR(*mode))
 183                         break;
 184                 if (++entrylen == namelen) {
 185                         hashcpy(result, sha1);
 186                         return 0;
 187                 }
 188                 return get_tree_entry(sha1, name + entrylen, result, mode);
 189         }
 190         return -1;
 191 }
 192
 193 int get_tree_entry(const unsigned char *tree_sha1, const char *name, unsigned char *sha1, unsigned *mode)
 194 {
 195         int retval;
 196         void *tree;
 197         unsigned long size;
 198         struct tree_desc t;
 199         unsigned char root[20];
 200
 201         tree = read_object_with_reference(tree_sha1, tree_type, &size, root);
 202         if (!tree)
 203                 return -1;
 204
 205         if (name[0] == '\0') {
 206                 hashcpy(sha1, root);
 207                 return 0;
 208         }
 209
 210         init_tree_desc(&t, tree, size);
 211         retval = find_tree_entry(&t, name, sha1, mode);
 212         free(tree);
 213         return retval;
 214 }