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The `struct dir_iterator` is a helper that allows us to iterate through directory entries. This iterator returns entries in the exact same order as readdir(3P) does -- or in other words, it guarantees no specific order at all. This is about to become problematic as we are introducing a new reflog subcommand to list reflogs. As the "files" backend uses the directory iterator to enumerate reflogs, returning reflog names and exposing them to the user would inherit the indeterministic ordering. Naturally, it would make for a terrible user interface to show a list with no discernible order. While this could be handled at a higher level by the new subcommand itself by collecting and ordering the reflogs, this would be inefficient because we would first have to collect all reflogs before we can sort them, which would introduce additional latency when there are many reflogs. Instead, introduce a new option into the directory iterator that asks for its entries to be yielded in lexicographical order. If set, the iterator will read all directory entries greedily and sort them before we start to iterate over them. While this will of course also incur overhead as we cannot yield the directory entries immediately, it should at least be more efficient than having to sort the complete list of reflogs as we only need to sort one directory at a time. This functionality will be used in a follow-up commit. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
118 lines
3.7 KiB
C
118 lines
3.7 KiB
C
#ifndef DIR_ITERATOR_H
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#define DIR_ITERATOR_H
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#include "strbuf.h"
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/*
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* Iterate over a directory tree.
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*
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* Iterate over a directory tree, recursively, including paths of all
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* types and hidden paths. Skip "." and ".." entries and don't follow
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* symlinks except for the original path. Note that the original path
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* is not included in the iteration.
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*
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* Every time dir_iterator_advance() is called, update the members of
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* the dir_iterator structure to reflect the next path in the
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* iteration. The order that paths are iterated over within a
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* directory is undefined, directory paths are always given before
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* their contents.
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*
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* A typical iteration looks like this:
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*
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* int ok;
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* unsigned int flags = DIR_ITERATOR_PEDANTIC;
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* struct dir_iterator *iter = dir_iterator_begin(path, flags);
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*
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* if (!iter)
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* goto error_handler;
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*
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* while ((ok = dir_iterator_advance(iter)) == ITER_OK) {
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* if (want_to_stop_iteration()) {
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* ok = dir_iterator_abort(iter);
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* break;
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* }
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*
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* // Access information about the current path:
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* if (S_ISDIR(iter->st.st_mode))
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* printf("%s is a directory\n", iter->relative_path);
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* }
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*
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* if (ok != ITER_DONE)
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* handle_error();
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*
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* Callers are allowed to modify iter->path while they are working,
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* but they must restore it to its original contents before calling
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* dir_iterator_advance() again.
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*/
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/*
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* Flags for dir_iterator_begin:
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*
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* - DIR_ITERATOR_PEDANTIC: override dir-iterator's default behavior
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* in case of an error at dir_iterator_advance(), which is to keep
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* looking for a next valid entry. With this flag, resources are freed
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* and ITER_ERROR is returned immediately. In both cases, a meaningful
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* warning is emitted. Note: ENOENT errors are always ignored so that
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* the API users may remove files during iteration.
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*
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* - DIR_ITERATOR_SORTED: sort directory entries alphabetically.
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*/
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#define DIR_ITERATOR_PEDANTIC (1 << 0)
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#define DIR_ITERATOR_SORTED (1 << 1)
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struct dir_iterator {
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/* The current path: */
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struct strbuf path;
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/*
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* The current path relative to the starting path. This part
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* of the path always uses "/" characters to separate path
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* components:
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*/
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const char *relative_path;
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/* The current basename: */
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const char *basename;
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/*
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* The result of calling lstat() on path.
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*/
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struct stat st;
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};
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/*
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* Start a directory iteration over path with the combination of
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* options specified by flags. On success, return a dir_iterator
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* that holds the internal state of the iteration. In case of
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* failure, return NULL and set errno accordingly.
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*
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* The iteration includes all paths under path, not including path
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* itself and not including "." or ".." entries.
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*
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* Parameters are:
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* - path is the starting directory. An internal copy will be made.
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* - flags is a combination of the possible flags to initialize a
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* dir-iterator or 0 for default behavior.
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*/
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struct dir_iterator *dir_iterator_begin(const char *path, unsigned int flags);
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/*
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* Advance the iterator to the first or next item and return ITER_OK.
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* If the iteration is exhausted, free the dir_iterator and any
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* resources associated with it and return ITER_DONE.
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*
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* It is a bug to use iterator or call this function again after it
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* has returned ITER_DONE or ITER_ERROR (which may be returned iff
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* the DIR_ITERATOR_PEDANTIC flag was set).
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*/
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int dir_iterator_advance(struct dir_iterator *iterator);
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/*
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* End the iteration before it has been exhausted. Free the
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* dir_iterator and any associated resources and return ITER_DONE. On
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* error, free the dir_iterator and return ITER_ERROR.
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*/
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int dir_iterator_abort(struct dir_iterator *iterator);
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#endif
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