tree-walk.h

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