tree-walk.h

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