tree-walk.h

   1 #ifndef TREE_WALK_H
   2 #define TREE_WALK_H
   3
   4 #include "hash.h"
   5
   6 struct index_state;
   7 struct repository;
   8
   9 /**
  10  * The tree walking API is used to traverse and inspect trees.
  11  */
  12
  13 /**
  14  * An entry in a tree. Each entry has a sha1 identifier, pathname, and mode.
  15  */
  16 struct name_entry {
  17         struct object_id oid;
  18         const char *path;
  19         int pathlen;
  20         unsigned int mode;
  21 };
  22
  23 /**
  24  * A semi-opaque data structure used to maintain the current state of the walk.
  25  */
  26 struct tree_desc {
  27         const struct git_hash_algo *algo;
  28         /*
  29          * pointer into the memory representation of the tree. It always
  30          * points at the current entry being visited.
  31          */
  32         const void *buffer;
  33
  34         /* points to the current entry being visited. */
  35         struct name_entry entry;
  36
  37         /* counts the number of bytes left in the `buffer`. */
  38         unsigned int size;
  39
  40         /* option flags passed via init_tree_desc_gently() */
  41         enum tree_desc_flags {
  42                 TREE_DESC_RAW_MODES = (1 << 0),
  43         } flags;
  44 };
  45
  46 /**
  47  * Decode the entry currently being visited (the one pointed to by
  48  * `tree_desc's` `entry` member) and return the sha1 of the entry. The
  49  * `pathp` and `modep` arguments are set to the entry's pathname and mode
  50  * respectively.
  51  */
  52 static inline const struct object_id *tree_entry_extract(struct tree_desc *desc, const char **pathp, unsigned short *modep)
  53 {
  54         *pathp = desc->entry.path;
  55         *modep = desc->entry.mode;
  56         return &desc->entry.oid;
  57 }
  58
  59 /**
  60  * Calculate the length of a tree entry's pathname. This utilizes the
  61  * memory structure of a tree entry to avoid the overhead of using a
  62  * generic strlen().
  63  */
  64 static inline int tree_entry_len(const struct name_entry *ne)
  65 {
  66         return ne->pathlen;
  67 }
  68
  69 /*
  70  * The _gently versions of these functions warn and return false on a
  71  * corrupt tree entry rather than dying,
  72  */
  73
  74 /**
  75  * Walk to the next entry in a tree. This is commonly used in conjunction
  76  * with `tree_entry_extract` to inspect the current entry.
  77  */
  78 void update_tree_entry(struct tree_desc *);
  79
  80 int update_tree_entry_gently(struct tree_desc *);
  81
  82 /**
  83  * Initialize a `tree_desc` and decode its first entry. The buffer and
  84  * size parameters are assumed to be the same as the buffer and size
  85  * members of `struct tree`.
  86  */
  87 void init_tree_desc(struct tree_desc *desc, const struct object_id *tree_oid,
  88                     const void *buf, unsigned long size);
  89
  90 int init_tree_desc_gently(struct tree_desc *desc, const struct object_id *oid,
  91                           const void *buf, unsigned long size,
  92                           enum tree_desc_flags flags);
  93
  94 /*
  95  * Visit the next entry in a tree. Returns 1 when there are more entries
  96  * left to visit and 0 when all entries have been visited. This is
  97  * commonly used in the test of a while loop.
  98  */
  99 int tree_entry(struct tree_desc *, struct name_entry *);
 100
 101 int tree_entry_gently(struct tree_desc *, struct name_entry *);
 102
 103 /**
 104  * Initialize a `tree_desc` and decode its first entry given the
 105  * object ID of a tree. Returns the `buffer` member if the latter
 106  * is a valid tree identifier and NULL otherwise.
 107  */
 108 void *fill_tree_descriptor(struct repository *r,
 109                            struct tree_desc *desc,
 110                            const struct object_id *oid);
 111
 112 struct traverse_info;
 113 typedef int (*traverse_callback_t)(int n, unsigned long mask, unsigned long dirmask, struct name_entry *entry, struct traverse_info *);
 114
 115 /**
 116  * Traverse `n` number of trees in parallel. The `fn` callback member of
 117  * `traverse_info` is called once for each tree entry.
 118  */
 119 int traverse_trees(struct index_state *istate, int n, struct tree_desc *t, struct traverse_info *info);
 120
 121 enum get_oid_result get_tree_entry_follow_symlinks(struct repository *r, struct object_id *tree_oid, const char *name, struct object_id *result, struct strbuf *result_path, unsigned short *mode);
 122
 123 /**
 124  * A structure used to maintain the state of a traversal.
 125  */
 126 struct traverse_info {
 127         const char *traverse_path;
 128
 129         /*
 130          * points to the traverse_info which was used to descend into the
 131          * current tree. If this is the top-level tree `prev` will point to
 132          * a dummy traverse_info.
 133          */
 134         struct traverse_info *prev;
 135
 136         /* is the entry for the current tree (if the tree is a subtree). */
 137         const char *name;
 138
 139         size_t namelen;
 140         unsigned mode;
 141
 142         /* is the length of the full path for the current tree. */
 143         size_t pathlen;
 144
 145         struct pathspec *pathspec;
 146
 147         /* can be used by callbacks to maintain directory-file conflicts. */
 148         unsigned long df_conflicts;
 149
 150         /* a callback called for each entry in the tree.
 151          *
 152          * The arguments passed to the traverse callback are as follows:
 153          *
 154          * - `n` counts the number of trees being traversed.
 155          *
 156          * - `mask` has its nth bit set if something exists in the nth entry.
 157          *
 158          * - `dirmask` has its nth bit set if the nth tree's entry is a directory.
 159          *
 160          * - `entry` is an array of size `n` where the nth entry is from the nth tree.
 161          *
 162          * - `info` maintains the state of the traversal.
 163          *
 164          * Returning a negative value will terminate the traversal. Otherwise the
 165          * return value is treated as an update mask. If the nth bit is set the nth tree
 166          * will be updated and if the bit is not set the nth tree entry will be the
 167          * same in the next callback invocation.
 168          */
 169         traverse_callback_t fn;
 170
 171         /* can be anything the `fn` callback would want to use. */
 172         void *data;
 173
 174         /* tells whether to stop at the first error or not. */
 175         int show_all_errors;
 176 };
 177
 178 /**
 179  * Find an entry in a tree given a pathname and the sha1 of a tree to
 180  * search. Returns 0 if the entry is found and -1 otherwise. The third
 181  * and fourth parameters are set to the entry's sha1 and mode respectively.
 182  */
 183 int get_tree_entry(struct repository *, const struct object_id *, const char *, struct object_id *, unsigned short *);
 184
 185 /**
 186  * Generate the full pathname of a tree entry based from the root of the
 187  * traversal. For example, if the traversal has recursed into another
 188  * tree named "bar" the pathname of an entry "baz" in the "bar"
 189  * tree would be "bar/baz".
 190  */
 191 char *make_traverse_path(char *path, size_t pathlen, const struct traverse_info *info,
 192                          const char *name, size_t namelen);
 193
 194 /**
 195  * Convenience wrapper to `make_traverse_path` into a strbuf.
 196  */
 197 void strbuf_make_traverse_path(struct strbuf *out,
 198                                const struct traverse_info *info,
 199                                const char *name, size_t namelen);
 200
 201 /**
 202  * Initialize a `traverse_info` given the pathname of the tree to start
 203  * traversing from.
 204  */
 205 void setup_traverse_info(struct traverse_info *info, const char *base);
 206
 207 /**
 208  * Calculate the length of a pathname returned by `make_traverse_path`.
 209  * This utilizes the memory structure of a tree entry to avoid the
 210  * overhead of using a generic strlen().
 211  */
 212 static inline size_t traverse_path_len(const struct traverse_info *info,
 213                                        size_t namelen)
 214 {
 215         return st_add(info->pathlen, namelen);
 216 }
 217
 218 /* in general, positive means "kind of interesting" */
 219 enum interesting {
 220         all_entries_not_interesting = -1, /* no, and no subsequent entries will be either */
 221         entry_not_interesting = 0,
 222         entry_interesting = 1,
 223         all_entries_interesting = 2 /* yes, and all subsequent entries will be */
 224 };
 225
 226 enum interesting tree_entry_interesting(struct index_state *istate,
 227                                         const struct name_entry *,
 228                                         struct strbuf *,
 229                                         const struct pathspec *ps);
 230
 231 #endif