From 3012397e0327f5e4dfd1d1183a792268429744ae Mon Sep 17 00:00:00 2001 From: Matheus Tavares Date: Wed, 10 Jul 2019 20:58:59 -0300 Subject: dir-iterator: refactor state machine model dir_iterator_advance() is a large function with two nested loops. Let's improve its readability factoring out three functions and simplifying its mechanics. The refactored model will no longer depend on level.initialized and level.dir_state to keep track of the iteration state and will perform on a single loop. Also, dir_iterator_begin() currently does not check if the given string represents a valid directory path. Since the refactored model will have to stat() the given path at initialization, let's also check for this kind of error and make dir_iterator_begin() return NULL, on failures, with errno appropriately set. And add tests for this new behavior. Improve documentation at dir-iteration.h and code comments at dir-iterator.c to reflect the changes and eliminate possible ambiguities. Finally, adjust refs/files-backend.c to check for now possible dir_iterator_begin() failures. Original-patch-by: Daniel Ferreira Signed-off-by: Matheus Tavares Signed-off-by: Junio C Hamano --- dir-iterator.c | 234 ++++++++++++++++++++++++++++++--------------------------- 1 file changed, 122 insertions(+), 112 deletions(-) (limited to 'dir-iterator.c') diff --git a/dir-iterator.c b/dir-iterator.c index 0c8880868a..594fe4d67b 100644 --- a/dir-iterator.c +++ b/dir-iterator.c @@ -4,8 +4,6 @@ #include "dir-iterator.h" struct dir_iterator_level { - int initialized; - DIR *dir; /* @@ -13,16 +11,6 @@ struct dir_iterator_level { * (including a trailing '/'): */ size_t prefix_len; - - /* - * The last action that has been taken with the current entry - * (needed for directories, which have to be included in the - * iteration and also iterated into): - */ - enum { - DIR_STATE_ITER, - DIR_STATE_RECURSE - } dir_state; }; /* @@ -34,9 +22,11 @@ struct dir_iterator_int { struct dir_iterator base; /* - * The number of levels currently on the stack. This is always - * at least 1, because when it becomes zero the iteration is - * ended and this struct is freed. + * The number of levels currently on the stack. After the first + * call to dir_iterator_begin(), if it succeeds to open the + * first level's dir, this will always be at least 1. Then, + * when it comes to zero the iteration is ended and this + * struct is freed. */ size_t levels_nr; @@ -50,113 +40,118 @@ struct dir_iterator_int { struct dir_iterator_level *levels; }; +/* + * Push a level in the iter stack and initialize it with information from + * the directory pointed by iter->base->path. It is assumed that this + * strbuf points to a valid directory path. Return 0 on success and -1 + * otherwise, leaving the stack unchanged. + */ +static int push_level(struct dir_iterator_int *iter) +{ + struct dir_iterator_level *level; + + ALLOC_GROW(iter->levels, iter->levels_nr + 1, iter->levels_alloc); + level = &iter->levels[iter->levels_nr++]; + + if (!is_dir_sep(iter->base.path.buf[iter->base.path.len - 1])) + strbuf_addch(&iter->base.path, '/'); + level->prefix_len = iter->base.path.len; + + level->dir = opendir(iter->base.path.buf); + if (!level->dir) { + if (errno != ENOENT) { + warning_errno("error opening directory '%s'", + iter->base.path.buf); + } + iter->levels_nr--; + return -1; + } + + return 0; +} + +/* + * Pop the top level on the iter stack, releasing any resources associated + * with it. Return the new value of iter->levels_nr. + */ +static int pop_level(struct dir_iterator_int *iter) +{ + struct dir_iterator_level *level = + &iter->levels[iter->levels_nr - 1]; + + if (level->dir && closedir(level->dir)) + warning_errno("error closing directory '%s'", + iter->base.path.buf); + level->dir = NULL; + + return --iter->levels_nr; +} + +/* + * Populate iter->base with the necessary information on the next iteration + * entry, represented by the given dirent de. Return 0 on success and -1 + * otherwise. + */ +static int prepare_next_entry_data(struct dir_iterator_int *iter, + struct dirent *de) +{ + strbuf_addstr(&iter->base.path, de->d_name); + /* + * We have to reset these because the path strbuf might have + * been realloc()ed at the previous strbuf_addstr(). + */ + iter->base.relative_path = iter->base.path.buf + + iter->levels[0].prefix_len; + iter->base.basename = iter->base.path.buf + + iter->levels[iter->levels_nr - 1].prefix_len; + + if (lstat(iter->base.path.buf, &iter->base.st)) { + if (errno != ENOENT) + warning_errno("failed to stat '%s'", iter->base.path.buf); + return -1; + } + + return 0; +} + int dir_iterator_advance(struct dir_iterator *dir_iterator) { struct dir_iterator_int *iter = (struct dir_iterator_int *)dir_iterator; + if (S_ISDIR(iter->base.st.st_mode)) { + if (push_level(iter) && iter->levels_nr == 0) { + /* Pushing the first level failed */ + return dir_iterator_abort(dir_iterator); + } + } + + /* Loop until we find an entry that we can give back to the caller. */ while (1) { + struct dirent *de; struct dir_iterator_level *level = &iter->levels[iter->levels_nr - 1]; - struct dirent *de; - if (!level->initialized) { - /* - * Note: dir_iterator_begin() ensures that - * path is not the empty string. - */ - if (!is_dir_sep(iter->base.path.buf[iter->base.path.len - 1])) - strbuf_addch(&iter->base.path, '/'); - level->prefix_len = iter->base.path.len; - - level->dir = opendir(iter->base.path.buf); - if (!level->dir && errno != ENOENT) { - warning_errno("error opening directory '%s'", + strbuf_setlen(&iter->base.path, level->prefix_len); + errno = 0; + de = readdir(level->dir); + + if (!de) { + if (errno) + warning_errno("error reading directory '%s'", iter->base.path.buf); - /* Popping the level is handled below */ - } - - level->initialized = 1; - } else if (S_ISDIR(iter->base.st.st_mode)) { - if (level->dir_state == DIR_STATE_ITER) { - /* - * The directory was just iterated - * over; now prepare to iterate into - * it. - */ - level->dir_state = DIR_STATE_RECURSE; - ALLOC_GROW(iter->levels, iter->levels_nr + 1, - iter->levels_alloc); - level = &iter->levels[iter->levels_nr++]; - level->initialized = 0; - continue; - } else { - /* - * The directory has already been - * iterated over and iterated into; - * we're done with it. - */ - } + else if (pop_level(iter) == 0) + return dir_iterator_abort(dir_iterator); + continue; } - if (!level->dir) { - /* - * This level is exhausted (or wasn't opened - * successfully); pop up a level. - */ - if (--iter->levels_nr == 0) - return dir_iterator_abort(dir_iterator); + if (is_dot_or_dotdot(de->d_name)) + continue; + if (prepare_next_entry_data(iter, de)) continue; - } - /* - * Loop until we find an entry that we can give back - * to the caller: - */ - while (1) { - strbuf_setlen(&iter->base.path, level->prefix_len); - errno = 0; - de = readdir(level->dir); - - if (!de) { - /* This level is exhausted; pop up a level. */ - if (errno) { - warning_errno("error reading directory '%s'", - iter->base.path.buf); - } else if (closedir(level->dir)) - warning_errno("error closing directory '%s'", - iter->base.path.buf); - - level->dir = NULL; - if (--iter->levels_nr == 0) - return dir_iterator_abort(dir_iterator); - break; - } - - if (is_dot_or_dotdot(de->d_name)) - continue; - - strbuf_addstr(&iter->base.path, de->d_name); - if (lstat(iter->base.path.buf, &iter->base.st) < 0) { - if (errno != ENOENT) - warning_errno("failed to stat '%s'", - iter->base.path.buf); - continue; - } - - /* - * We have to set these each time because - * the path strbuf might have been realloc()ed. - */ - iter->base.relative_path = - iter->base.path.buf + iter->levels[0].prefix_len; - iter->base.basename = - iter->base.path.buf + level->prefix_len; - level->dir_state = DIR_STATE_ITER; - - return ITER_OK; - } + return ITER_OK; } } @@ -187,17 +182,32 @@ struct dir_iterator *dir_iterator_begin(const char *path) { struct dir_iterator_int *iter = xcalloc(1, sizeof(*iter)); struct dir_iterator *dir_iterator = &iter->base; - - if (!path || !*path) - BUG("empty path passed to dir_iterator_begin()"); + int saved_errno; strbuf_init(&iter->base.path, PATH_MAX); strbuf_addstr(&iter->base.path, path); ALLOC_GROW(iter->levels, 10, iter->levels_alloc); + iter->levels_nr = 0; - iter->levels_nr = 1; - iter->levels[0].initialized = 0; + /* + * Note: stat already checks for NULL or empty strings and + * inexistent paths. + */ + if (stat(iter->base.path.buf, &iter->base.st) < 0) { + saved_errno = errno; + goto error_out; + } + + if (!S_ISDIR(iter->base.st.st_mode)) { + saved_errno = ENOTDIR; + goto error_out; + } return dir_iterator; + +error_out: + dir_iterator_abort(dir_iterator); + errno = saved_errno; + return NULL; } -- cgit v1.2.3