dir-iterator.h

   1 #ifndef DIR_ITERATOR_H
   2 #define DIR_ITERATOR_H
   3
   4 #include "strbuf.h"
   5
   6 /*
   7  * Iterate over a directory tree.
   8  *
   9  * Iterate over a directory tree, recursively, including paths of all
  10  * types and hidden paths. Skip "." and ".." entries and don't follow
  11  * symlinks except for the original path. Note that the original path
  12  * is not included in the iteration.
  13  *
  14  * Every time dir_iterator_advance() is called, update the members of
  15  * the dir_iterator structure to reflect the next path in the
  16  * iteration. The order that paths are iterated over within a
  17  * directory is undefined, directory paths are always given before
  18  * their contents.
  19  *
  20  * A typical iteration looks like this:
  21  *
  22  *     int ok;
  23  *     unsigned int flags = DIR_ITERATOR_PEDANTIC;
  24  *     struct dir_iterator *iter = dir_iterator_begin(path, flags);
  25  *
  26  *     if (!iter)
  27  *             goto error_handler;
  28  *
  29  *     while ((ok = dir_iterator_advance(iter)) == ITER_OK) {
  30  *             if (want_to_stop_iteration()) {
  31  *                     ok = dir_iterator_abort(iter);
  32  *                     break;
  33  *             }
  34  *
  35  *             // Access information about the current path:
  36  *             if (S_ISDIR(iter->st.st_mode))
  37  *                     printf("%s is a directory\n", iter->relative_path);
  38  *     }
  39  *
  40  *     if (ok != ITER_DONE)
  41  *             handle_error();
  42  *
  43  * Callers are allowed to modify iter->path while they are working,
  44  * but they must restore it to its original contents before calling
  45  * dir_iterator_advance() again.
  46  */
  47
  48 /*
  49  * Flags for dir_iterator_begin:
  50  *
  51  * - DIR_ITERATOR_PEDANTIC: override dir-iterator's default behavior
  52  *   in case of an error at dir_iterator_advance(), which is to keep
  53  *   looking for a next valid entry. With this flag, resources are freed
  54  *   and ITER_ERROR is returned immediately. In both cases, a meaningful
  55  *   warning is emitted. Note: ENOENT errors are always ignored so that
  56  *   the API users may remove files during iteration.
  57  *
  58  * - DIR_ITERATOR_FOLLOW_SYMLINKS: make dir-iterator follow symlinks.
  59  *   i.e., linked directories' contents will be iterated over and
  60  *   iter->base.st will contain information on the referred files,
  61  *   not the symlinks themselves, which is the default behavior. Broken
  62  *   symlinks are ignored.
  63  *
  64  *   Note: setting DIR_ITERATOR_FOLLOW_SYMLINKS affects resolving the
  65  *   starting path as well (e.g., attempting to iterate starting at a
  66  *   symbolic link pointing to a directory without FOLLOW_SYMLINKS will
  67  *   result in an error).
  68  *
  69  * Warning: circular symlinks are also followed when
  70  * DIR_ITERATOR_FOLLOW_SYMLINKS is set. The iteration may end up with
  71  * an ELOOP if they happen and DIR_ITERATOR_PEDANTIC is set.
  72  */
  73 #define DIR_ITERATOR_PEDANTIC (1 << 0)
  74 #define DIR_ITERATOR_FOLLOW_SYMLINKS (1 << 1)
  75
  76 struct dir_iterator {
  77         /* The current path: */
  78         struct strbuf path;
  79
  80         /*
  81          * The current path relative to the starting path. This part
  82          * of the path always uses "/" characters to separate path
  83          * components:
  84          */
  85         const char *relative_path;
  86
  87         /* The current basename: */
  88         const char *basename;
  89
  90         /*
  91          * The result of calling lstat() on path; or stat(), if the
  92          * DIR_ITERATOR_FOLLOW_SYMLINKS flag was set at
  93          * dir_iterator's initialization.
  94          */
  95         struct stat st;
  96 };
  97
  98 /*
  99  * Start a directory iteration over path with the combination of
 100  * options specified by flags. On success, return a dir_iterator
 101  * that holds the internal state of the iteration. In case of
 102  * failure, return NULL and set errno accordingly.
 103  *
 104  * The iteration includes all paths under path, not including path
 105  * itself and not including "." or ".." entries.
 106  *
 107  * Parameters are:
 108  *  - path is the starting directory. An internal copy will be made.
 109  *  - flags is a combination of the possible flags to initialize a
 110  *    dir-iterator or 0 for default behavior.
 111  */
 112 struct dir_iterator *dir_iterator_begin(const char *path, unsigned int flags);
 113
 114 /*
 115  * Advance the iterator to the first or next item and return ITER_OK.
 116  * If the iteration is exhausted, free the dir_iterator and any
 117  * resources associated with it and return ITER_DONE.
 118  *
 119  * It is a bug to use iterator or call this function again after it
 120  * has returned ITER_DONE or ITER_ERROR (which may be returned iff
 121  * the DIR_ITERATOR_PEDANTIC flag was set).
 122  */
 123 int dir_iterator_advance(struct dir_iterator *iterator);
 124
 125 /*
 126  * End the iteration before it has been exhausted. Free the
 127  * dir_iterator and any associated resources and return ITER_DONE. On
 128  * error, free the dir_iterator and return ITER_ERROR.
 129  */
 130 int dir_iterator_abort(struct dir_iterator *iterator);
 131
 132 #endif