From: Michihiro NAKAJIMA <ggcueroad@gmail.com>
Date: Wed, 19 Jan 2011 14:48:24 +0000 (-0500)
Subject: Try to eliminate fchdir() operation as much as we can in the directory
X-Git-Tag: v3.0.0a~736
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=8848af5f4b004de31831f9ec55b93fa7bfeaffc1;p=thirdparty%2Flibarchive.git

Try to eliminate fchdir() operation as much as we can in the directory
traversals, which is a new API for the read disk object.

SVN-Revision: 2926
---

diff --git a/libarchive/archive_read_disk_posix.c b/libarchive/archive_read_disk_posix.c
index 3fcca7108..fc0e1e43b 100644
--- a/libarchive/archive_read_disk_posix.c
+++ b/libarchive/archive_read_disk_posix.c
@@ -773,7 +773,7 @@ _archive_read_next_header2(struct archive *_a, struct archive_entry *entry)
 	struct tree *t;
 	const struct stat *st; /* info to use for this entry */
 	const struct stat *lst;/* lstat() information */
-	int descend, r;
+	int descend, fd = -1, r;
 
 	archive_check_magic(_a, ARCHIVE_READ_DISK_MAGIC,
 	    ARCHIVE_STATE_HEADER | ARCHIVE_STATE_DATA,
@@ -869,13 +869,35 @@ _archive_read_next_header2(struct archive *_a, struct archive_entry *entry)
 	archive_entry_copy_stat(entry, st);
 
 #if defined(HAVE_OPENAT) && defined(HAVE_FSTATAT) && defined(HAVE_FDOPENDIR)
-	/* Restore working directory. */
-	tree_enter_working_dir(t);
-#endif
+	/*
+	 * Open the current file to freely gather its metadata anywhere in
+	 * working directory.
+	 * Note: A symbolic link file cannot be opened with O_NOFOLLOW.
+	 */
+	if (a->follow_symlinks || archive_entry_filetype(entry) != AE_IFLNK)
+		fd = openat(tree_current_dir_fd(t), tree_current_access_path(t),
+		    (a->follow_symlinks)? O_RDONLY | O_NONBLOCK
+				        : O_RDONLY | O_NONBLOCK | O_NOFOLLOW);
+	/* Restore working directory if openat() operation failed or
+	 * the file is a symbolic link. */
+	if (fd < 0)
+		tree_enter_working_dir(t);
 
+	/* The current direcotry fd is needed at
+	 * archive_read_disk_entry_from_file() function to read link data
+	 * with readlinkat(). */
 	a->entry_wd_fd = tree_current_dir_fd(t);
-	/* Populate the archive_entry with metadata from the disk. */
-	r = archive_read_disk_entry_from_file(&(a->archive), entry, -1, st);
+#endif
+
+	/*
+	 * Populate the archive_entry with metadata from the disk.
+	 */
+	r = archive_read_disk_entry_from_file(&(a->archive), entry, fd, st);
+
+	/* Close the file descriptor used for reding the current file
+	 * metadata at archive_read_disk_entry_from_file(). */
+	if (fd >= 0)
+		close(fd);
 
 	/* Return to the initial directory. */
 	tree_enter_initial_dir(t);