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 #define MAX_TRAVERSE_TREES 8
  10
  11 /**
  12  * The tree walking API is used to traverse and inspect trees.
  13  */
  14
  15 /**
  16  * An entry in a tree. Each entry has a sha1 identifier, pathname, and mode.
  17  */
  18 struct name_entry {
  19         struct object_id oid;
  20         const char *path;
  21         int pathlen;
  22         unsigned int mode;
  23 };
  24
  25 /**
  26  * A semi-opaque data structure used to maintain the current state of the walk.
  27  */
  28 struct tree_desc {
  29         /*
  30          * pointer into the memory representation of the tree. It always
  31          * points at the current entry being visited.
  32          */
  33         const void *buffer;
  34
  35         /* points to the current entry being visited. */
  36         struct name_entry entry;
  37
  38         /* counts the number of bytes left in the `buffer`. */
  39         unsigned int size;
  40
  41         /* option flags passed via init_tree_desc_gently() */
  42         enum tree_desc_flags {
  43                 TREE_DESC_RAW_MODES = (1 << 0),
  44         } flags;
  45 };
  46
  47 /**
  48  * Decode the entry currently being visited (the one pointed to by
  49  * `tree_desc's` `entry` member) and return the sha1 of the entry. The
  50  * `pathp` and `modep` arguments are set to the entry's pathname and mode
  51  * respectively.
  52  */
  53 static inline const struct object_id *tree_entry_extract(struct tree_desc *desc, const char **pathp, unsigned short *modep)
  54 {
  55         *pathp = desc->entry.path;
  56         *modep = desc->entry.mode;
  57         return &desc->entry.oid;
  58 }
  59
  60 /**
  61  * Calculate the length of a tree entry's pathname. This utilizes the
  62  * memory structure of a tree entry to avoid the overhead of using a
  63  * generic strlen().
  64  */
  65 static inline int tree_entry_len(const struct name_entry *ne)
  66 {
  67         return ne->pathlen;
  68 }
  69
  70 /*
  71  * The _gently versions of these functions warn and return false on a
  72  * corrupt tree entry rather than dying,
  73  */
  74
  75 /**
  76  * Walk to the next entry in a tree. This is commonly used in conjunction
  77  * with `tree_entry_extract` to inspect the current entry.
  78  */
  79 void update_tree_entry(struct tree_desc *);
  80
  81 int update_tree_entry_gently(struct tree_desc *);
  82
  83 /**
  84  * Initialize a `tree_desc` and decode its first entry. The buffer and
  85  * size parameters are assumed to be the same as the buffer and size
  86  * members of `struct tree`.
  87  */
  88 void init_tree_desc(struct tree_desc *desc, const void *buf, unsigned long size);
  89
  90 int init_tree_desc_gently(struct tree_desc *desc, const void *buf, unsigned long size,
  91                           enum tree_desc_flags flags);
  92
  93 /*
  94  * Visit the next entry in a tree. Returns 1 when there are more entries
  95  * left to visit and 0 when all entries have been visited. This is
  96  * commonly used in the test of a while loop.
  97  */
  98 int tree_entry(struct tree_desc *, struct name_entry *);
  99
 100 int tree_entry_gently(struct tree_desc *, struct name_entry *);
 101
 102 /**
 103  * Initialize a `tree_desc` and decode its first entry given the
 104  * object ID of a tree. Returns the `buffer` member if the latter
 105  * is a valid tree identifier and NULL otherwise.
 106  */
 107 void *fill_tree_descriptor(struct repository *r,
 108                            struct tree_desc *desc,
 109                            const struct object_id *oid);
 110
 111 struct traverse_info;
 112 typedef int (*traverse_callback_t)(int n, unsigned long mask, unsigned long dirmask, struct name_entry *entry, struct traverse_info *);
 113
 114 /**
 115  * Traverse `n` number of trees in parallel. The `fn` callback member of
 116  * `traverse_info` is called once for each tree entry.
 117  */
 118 int traverse_trees(struct index_state *istate, int n, struct tree_desc *t, struct traverse_info *info);
 119
 120 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);
 121
 122 /**
 123  * A structure used to maintain the state of a traversal.
 124  */
 125 struct traverse_info {
 126         const char *traverse_path;
 127
 128         /*
 129          * points to the traverse_info which was used to descend into the
 130          * current tree. If this is the top-level tree `prev` will point to
 131          * a dummy traverse_info.
 132          */
 133         struct traverse_info *prev;
 134
 135         /* is the entry for the current tree (if the tree is a subtree). */
 136         const char *name;
 137
 138         size_t namelen;
 139         unsigned mode;
 140
 141         /* is the length of the full path for the current tree. */
 142         size_t pathlen;
 143
 144         struct pathspec *pathspec;
 145
 146         /* can be used by callbacks to maintain directory-file conflicts. */
 147         unsigned long df_conflicts;
 148
 149         /* a callback called for each entry in the tree.
 150          *
 151          * The arguments passed to the traverse callback are as follows:
 152          *
 153          * - `n` counts the number of trees being traversed.
 154          *
 155          * - `mask` has its nth bit set if something exists in the nth entry.
 156          *
 157          * - `dirmask` has its nth bit set if the nth tree's entry is a directory.
 158          *
 159          * - `entry` is an array of size `n` where the nth entry is from the nth tree.
 160          *
 161          * - `info` maintains the state of the traversal.
 162          *
 163          * Returning a negative value will terminate the traversal. Otherwise the
 164          * return value is treated as an update mask. If the nth bit is set the nth tree
 165          * will be updated and if the bit is not set the nth tree entry will be the
 166          * same in the next callback invocation.
 167          */
 168         traverse_callback_t fn;
 169
 170         /* can be anything the `fn` callback would want to use. */
 171         void *data;
 172
 173         /* tells whether to stop at the first error or not. */
 174         int show_all_errors;
 175 };
 176
 177 /**
 178  * Find an entry in a tree given a pathname and the sha1 of a tree to
 179  * search. Returns 0 if the entry is found and -1 otherwise. The third
 180  * and fourth parameters are set to the entry's sha1 and mode respectively.
 181  */
 182 int get_tree_entry(struct repository *, const struct object_id *, const char *, struct object_id *, unsigned short *);
 183
 184 /**
 185  * Generate the full pathname of a tree entry based from the root of the
 186  * traversal. For example, if the traversal has recursed into another
 187  * tree named "bar" the pathname of an entry "baz" in the "bar"
 188  * tree would be "bar/baz".
 189  */
 190 char *make_traverse_path(char *path, size_t pathlen, const struct traverse_info *info,
 191                          const char *name, size_t namelen);
 192
 193 /**
 194  * Convenience wrapper to `make_traverse_path` into a strbuf.
 195  */
 196 void strbuf_make_traverse_path(struct strbuf *out,
 197                                const struct traverse_info *info,
 198                                const char *name, size_t namelen);
 199
 200 /**
 201  * Initialize a `traverse_info` given the pathname of the tree to start
 202  * traversing from.
 203  */
 204 void setup_traverse_info(struct traverse_info *info, const char *base);
 205
 206 /**
 207  * Calculate the length of a pathname returned by `make_traverse_path`.
 208  * This utilizes the memory structure of a tree entry to avoid the
 209  * overhead of using a generic strlen().
 210  */
 211 static inline size_t traverse_path_len(const struct traverse_info *info,
 212                                        size_t namelen)
 213 {
 214         return st_add(info->pathlen, namelen);
 215 }
 216
 217 /* in general, positive means "kind of interesting" */
 218 enum interesting {
 219         all_entries_not_interesting = -1, /* no, and no subsequent entries will be either */
 220         entry_not_interesting = 0,
 221         entry_interesting = 1,
 222         all_entries_interesting = 2 /* yes, and all subsequent entries will be */
 223 };
 224
 225 enum interesting tree_entry_interesting(struct index_state *istate,
 226                                         const struct name_entry *,
 227                                         struct strbuf *, int,
 228                                         const struct pathspec *ps);
 229
 230 #endif