tree-walk.h

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