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