notes.h

   1 #ifndef NOTES_H
   2 #define NOTES_H
   3
   4 /*
   5  * Function type for combining two notes annotating the same object.
   6  *
   7  * When adding a new note annotating the same object as an existing note, it is
   8  * up to the caller to decide how to combine the two notes. The decision is
   9  * made by passing in a function of the following form. The function accepts
  10  * two SHA1s -- of the existing note and the new note, respectively. The
  11  * function then combines the notes in whatever way it sees fit, and writes the
  12  * resulting SHA1 into the first SHA1 argument (cur_sha1). A non-zero return
  13  * value indicates failure.
  14  *
  15  * The two given SHA1s must both be non-NULL and different from each other.
  16  *
  17  * The default combine_notes function (you get this when passing NULL) is
  18  * combine_notes_concatenate(), which appends the contents of the new note to
  19  * the contents of the existing note.
  20  */
  21 typedef int combine_notes_fn(unsigned char *cur_sha1, const unsigned char *new_sha1);
  22
  23 /* Common notes combinators */
  24 int combine_notes_concatenate(unsigned char *cur_sha1, const unsigned char *new_sha1);
  25 int combine_notes_overwrite(unsigned char *cur_sha1, const unsigned char *new_sha1);
  26 int combine_notes_ignore(unsigned char *cur_sha1, const unsigned char *new_sha1);
  27
  28 /*
  29  * Notes tree object
  30  *
  31  * Encapsulates the internal notes tree structure associated with a notes ref.
  32  * Whenever a struct notes_tree pointer is required below, you may pass NULL in
  33  * order to use the default/internal notes tree. E.g. you only need to pass a
  34  * non-NULL value if you need to refer to several different notes trees
  35  * simultaneously.
  36  */
  37 extern struct notes_tree {
  38         struct int_node *root;
  39         struct non_note *first_non_note, *prev_non_note;
  40         char *ref;
  41         combine_notes_fn *combine_notes;
  42         int initialized;
  43 } default_notes_tree;
  44
  45 /*
  46  * Flags controlling behaviour of notes tree initialization
  47  *
  48  * Default behaviour is to initialize the notes tree from the tree object
  49  * specified by the given (or default) notes ref.
  50  */
  51 #define NOTES_INIT_EMPTY 1
  52
  53 /*
  54  * Initialize the given notes_tree with the notes tree structure at the given
  55  * ref. If given ref is NULL, the value of the $GIT_NOTES_REF environment
  56  * variable is used, and if that is missing, the default notes ref is used
  57  * ("refs/notes/commits").
  58  *
  59  * If you need to re-intialize a notes_tree structure (e.g. when switching from
  60  * one notes ref to another), you must first de-initialize the notes_tree
  61  * structure by calling free_notes(struct notes_tree *).
  62  *
  63  * If you pass t == NULL, the default internal notes_tree will be initialized.
  64  *
  65  * The combine_notes function that is passed becomes the default combine_notes
  66  * function for the given notes_tree. If NULL is passed, the default
  67  * combine_notes function is combine_notes_concatenate().
  68  *
  69  * Precondition: The notes_tree structure is zeroed (this can be achieved with
  70  * memset(t, 0, sizeof(struct notes_tree)))
  71  */
  72 void init_notes(struct notes_tree *t, const char *notes_ref,
  73                 combine_notes_fn combine_notes, int flags);
  74
  75 /*
  76  * Add the given note object to the given notes_tree structure
  77  *
  78  * IMPORTANT: The changes made by add_note() to the given notes_tree structure
  79  * are not persistent until a subsequent call to write_notes_tree() returns
  80  * zero.
  81  */
  82 void add_note(struct notes_tree *t, const unsigned char *object_sha1,
  83                 const unsigned char *note_sha1, combine_notes_fn combine_notes);
  84
  85 /*
  86  * Remove the given note object from the given notes_tree structure
  87  *
  88  * IMPORTANT: The changes made by remove_note() to the given notes_tree
  89  * structure are not persistent until a subsequent call to write_notes_tree()
  90  * returns zero.
  91  */
  92 void remove_note(struct notes_tree *t, const unsigned char *object_sha1);
  93
  94 /*
  95  * Get the note object SHA1 containing the note data for the given object
  96  *
  97  * Return NULL if the given object has no notes.
  98  */
  99 const unsigned char *get_note(struct notes_tree *t,
 100                 const unsigned char *object_sha1);
 101
 102 /*
 103  * Flags controlling behaviour of for_each_note()
 104  *
 105  * Default behaviour of for_each_note() is to traverse every single note object
 106  * in the given notes tree, unpacking subtree entries along the way.
 107  * The following flags can be used to alter the default behaviour:
 108  *
 109  * - DONT_UNPACK_SUBTREES causes for_each_note() NOT to unpack and recurse into
 110  *   subtree entries while traversing the notes tree. This causes notes within
 111  *   those subtrees NOT to be passed to the callback. Use this flag if you
 112  *   don't want to traverse _all_ notes, but only want to traverse the parts
 113  *   of the notes tree that have already been unpacked (this includes at least
 114  *   all notes that have been added/changed).
 115  *
 116  * - YIELD_SUBTREES causes any subtree entries that are encountered to be
 117  *   passed to the callback, before recursing into them. Subtree entries are
 118  *   not note objects, but represent intermediate directories in the notes
 119  *   tree. When passed to the callback, subtree entries will have a trailing
 120  *   slash in their path, which the callback may use to differentiate between
 121  *   note entries and subtree entries. Note that already-unpacked subtree
 122  *   entries are not part of the notes tree, and will therefore not be yielded.
 123  *   If this flag is used together with DONT_UNPACK_SUBTREES, for_each_note()
 124  *   will yield the subtree entry, but not recurse into it.
 125  */
 126 #define FOR_EACH_NOTE_DONT_UNPACK_SUBTREES 1
 127 #define FOR_EACH_NOTE_YIELD_SUBTREES 2
 128
 129 /*
 130  * Invoke the specified callback function for each note in the given notes_tree
 131  *
 132  * If the callback returns nonzero, the note walk is aborted, and the return
 133  * value from the callback is returned from for_each_note(). Hence, a zero
 134  * return value from for_each_note() indicates that all notes were walked
 135  * successfully.
 136  *
 137  * IMPORTANT: The callback function is NOT allowed to change the notes tree.
 138  * In other words, the following functions can NOT be invoked (on the current
 139  * notes tree) from within the callback:
 140  * - add_note()
 141  * - remove_note()
 142  * - free_notes()
 143  */
 144 typedef int each_note_fn(const unsigned char *object_sha1,
 145                 const unsigned char *note_sha1, char *note_path,
 146                 void *cb_data);
 147 int for_each_note(struct notes_tree *t, int flags, each_note_fn fn,
 148                 void *cb_data);
 149
 150 /*
 151  * Write the given notes_tree structure to the object database
 152  *
 153  * Creates a new tree object encapsulating the current state of the given
 154  * notes_tree, and stores its SHA1 into the 'result' argument.
 155  *
 156  * Returns zero on success, non-zero on failure.
 157  *
 158  * IMPORTANT: Changes made to the given notes_tree are not persistent until
 159  * this function has returned zero. Please also remember to create a
 160  * corresponding commit object, and update the appropriate notes ref.
 161  */
 162 int write_notes_tree(struct notes_tree *t, unsigned char *result);
 163
 164 /*
 165  * Remove all notes annotating non-existing objects from the given notes tree
 166  *
 167  * All notes in the given notes_tree that are associated with objects that no
 168  * longer exist in the database, are removed from the notes tree.
 169  *
 170  * IMPORTANT: The changes made by prune_notes() to the given notes_tree
 171  * structure are not persistent until a subsequent call to write_notes_tree()
 172  * returns zero.
 173  */
 174 void prune_notes(struct notes_tree *t);
 175
 176 /*
 177  * Free (and de-initialize) the given notes_tree structure
 178  *
 179  * IMPORTANT: Changes made to the given notes_tree since the last, successful
 180  * call to write_notes_tree() will be lost.
 181  */
 182 void free_notes(struct notes_tree *t);
 183
 184 /* Flags controlling how notes are formatted */
 185 #define NOTES_SHOW_HEADER 1
 186 #define NOTES_INDENT 2
 187
 188 /*
 189  * Fill the given strbuf with the notes associated with the given object.
 190  *
 191  * If the given notes_tree structure is not initialized, it will be auto-
 192  * initialized to the default value (see documentation for init_notes() above).
 193  * If the given notes_tree is NULL, the internal/default notes_tree will be
 194  * used instead.
 195  *
 196  * 'flags' is a bitwise combination of the above formatting flags.
 197  */
 198 void format_note(struct notes_tree *t, const unsigned char *object_sha1,
 199                 struct strbuf *sb, const char *output_encoding, int flags);
 200
 201 #endif