diff options
| -rw-r--r-- | usr.bin/tar/tree.c | 50 |
1 files changed, 29 insertions, 21 deletions
diff --git a/usr.bin/tar/tree.c b/usr.bin/tar/tree.c index 84a1e2d..8bf413c 100644 --- a/usr.bin/tar/tree.c +++ b/usr.bin/tar/tree.c @@ -393,45 +393,58 @@ tree_current_lstat(struct tree *t) } /* - * Test whether current entry is a dir or dir link. + * Test whether current entry is a dir or link to a dir. */ int tree_current_is_dir(struct tree *t) { - /* If we've already pulled stat(), just use that. */ - if (t->flags & hasStat) - return (S_ISDIR(tree_current_stat(t)->st_mode)); - - /* If we've already pulled lstat(), we may be able to use that. */ + /* + * If we already have lstat() info, then try some + * cheap tests to determine if this is a dir. + */ if (t->flags & hasLstat) { /* If lstat() says it's a dir, it must be a dir. */ if (S_ISDIR(tree_current_lstat(t)->st_mode)) return 1; - /* If it's not a dir and not a link, we're done. */ + /* Not a dir; might be a link to a dir. */ + /* If it's not a link, then it's not a link to a dir. */ if (!S_ISLNK(tree_current_lstat(t)->st_mode)) return 0; /* - * If the above two tests fail, then it's a link, but - * we don't know whether it's a link to a dir or a - * non-dir. + * It's a link, but we don't know what it's a link to, + * so we'll have to use stat(). */ } - /* TODO: Use a more efficient mechanism when available. */ + /* Use the definitive test. Hopefully this is cached. */ return (S_ISDIR(tree_current_stat(t)->st_mode)); } /* - * Test whether current entry is a physical directory. + * Test whether current entry is a physical directory. Usually, we + * already have at least one of stat() or lstat() in memory, so we + * use tricks to try to avoid an extra trip to the disk. */ int tree_current_is_physical_dir(struct tree *t) { - /* If we've already pulled lstat(), just use that. */ - if (t->flags & hasLstat) - return (S_ISDIR(tree_current_lstat(t)->st_mode)); - /* TODO: Use a more efficient mechanism when available. */ + /* + * If stat() says it isn't a dir, then it's not a dir. + * If stat() data is cached, this check is free, so do it first. + */ + if ((t->flags & hasStat) + && (!S_ISDIR(tree_current_stat(t)->st_mode))) + return 0; + + /* + * Either stat() said it was a dir (in which case, we have + * to determine whether it's really a link to a dir) or + * stat() info wasn't available. So we use lstat(), which + * hopefully is already cached. + */ + + /* Use the definitive test. Hopefully this is cached. */ return (S_ISDIR(tree_current_lstat(t)->st_mode)); } @@ -441,11 +454,6 @@ tree_current_is_physical_dir(struct tree *t) int tree_current_is_physical_link(struct tree *t) { - /* If we've already pulled lstat(), just use that. */ - if (t->flags & hasLstat) - return (S_ISLNK(tree_current_lstat(t)->st_mode)); - - /* TODO: Use a more efficient mechanism when available. */ return (S_ISLNK(tree_current_lstat(t)->st_mode)); } |
