tree-walk.h

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