2 * trie.h: functions to build and search a trie-like structure
3 * mapping pathnames to file records.
9 * An entry in the trie file describing an actual file.
12 unsigned long long size
;
13 unsigned long long atime
;
16 /* ----------------------------------------------------------------------
17 * Functions which can be passed a list of pathnames and file data
18 * in strict order, and will build up a trie and write it out to a
22 typedef struct triebuild triebuild
;
25 * Create a new trie-building context given a writable file
26 * descriptor, which should point to the start of an empty file.
28 triebuild
*triebuild_new(int fd
);
31 * Add a trie_file record to the trie. The pathnames should appear
32 * in trie collation order (i.e. strict ASCII sorting order except
33 * that / is moved so that it sorts before any other non-NUL
34 * character), on penalty of assertion failure.
36 void triebuild_add(triebuild
*tb
, const char *pathname
,
37 const struct trie_file
*file
);
40 * Put the finishing touches to the contents of the output file
41 * once all the trie_file records are present. Returns the total
42 * number of elements in the trie.
44 int triebuild_finish(triebuild
*tb
);
47 * Free the context. (Does not close the file, but may leave the
48 * file pointer in an arbitrary place.)
50 void triebuild_free(triebuild
*tb
);
52 /* ----------------------------------------------------------------------
53 * Anomalous function which modifies a trie after it's memory-mapped.
57 * Invent new fake atimes for each directory in the trie, by
58 * taking the maximum (latest) of the directory's previously
59 * stored atime and the atimes of everything below it.
61 void trie_fake_dir_atimes(void *t
);
63 /* ----------------------------------------------------------------------
64 * Functions to query a trie given a pointer to the start of the
69 * Return the path separator character in use in the trie.
71 char trie_pathsep(const void *t
);
74 * Return the length of the longest pathname stored in the trie,
75 * including its trailing NUL.
77 size_t trie_maxpathlen(const void *t
);
80 * Determine the total number of entries in the trie which sort
81 * strictly before the given pathname (irrespective of whether the
82 * pathname actually exists in the trie).
84 unsigned long trie_before(const void *t
, const char *pathname
);
87 * Return the pathname for the nth entry in the trie, written into
88 * the supplied buffer (which must be large enough, i.e. at least
89 * trie_maxpathlen(t) bytes).
91 void trie_getpath(const void *t
, unsigned long n
, char *buf
);
94 * Return the total number of entries in the whole trie.
96 unsigned long trie_count(const void *t
);
99 * Enumerate all the trie_file records in the trie, in sequence,
100 * and return pointers to their trie_file structures. Returns NULL
101 * at end of list, naturally.
103 * Optionally returns the pathnames as well: if "buf" is non-NULL
104 * then it is expected to point to a buffer large enough to store
105 * all the pathnames in the trie (i.e. at least trie_maxpathlen(t)
106 * bytes). This buffer is also expected to remain unchanged
107 * between calls to triewalk_next(), or else the returned
108 * pathnames will be corrupted.
110 typedef struct triewalk triewalk
;
111 triewalk
*triewalk_new(const void *t
);
112 const struct trie_file
*triewalk_next(triewalk
*tw
, char *buf
);
113 void triewalk_rebase(triewalk
*tw
, const void *t
);
114 void triewalk_free(triewalk
*tw
);
116 /* ----------------------------------------------------------------------
117 * The trie file also contains an index managed by index.h, so we
118 * must be able to ask about that too.
120 void trie_set_index_offset(void *t
, off_t ptr
);
121 off_t
trie_get_index_offset(const void *t
);
123 /* ----------------------------------------------------------------------
124 * Utility functions not directly involved with the trie.
128 * Given a pathname in a buffer, adjust the pathname in place so
129 * that it points at a string which, when passed to trie_before,
130 * will reliably return the index of the thing that comes after
131 * that pathname and all its descendants. Usually this is done by
132 * suffixing ^A (since foo^A is guaranteeably the first thing that
133 * sorts after foo and foo/stuff); however, if the pathname
134 * actually ends in a path separator (e.g. if it's just "/"), that
135 * must be stripped off first.
137 void make_successor(char *pathbuf
);