Reduce performing fchdir().

For example, when the disk read object was opened with
archive_read_disk_open("file.txt")(not a directory),
performing fchdir() is really unneeded.

SVN-Revision: 2918

diff --git a/libarchive/archive_read_disk_posix.c b/libarchive/archive_read_disk_posix.c
index 3a5381b978caa63e95076ff77560c5976d18f174..16cd3fa76feb4c7fa6aef4d5ab220d7e91e110c6 100644 (file)
--- a/libarchive/archive_read_disk_posix.c
+++ b/libarchive/archive_read_disk_posix.c
@@ -211,7 +211,8 @@ struct tree {
 /* Definitions for tree.flags bitmap. */
 #define        hasStat         16 /* The st entry is valid. */
 #define        hasLstat        32 /* The lst entry is valid. */
-#define        needsChdir      64 /* Changing a working directory is needed. */
+#define        onWorkingDir    64 /* We are on the working dir where we are
+                           * reading directory entry at this time. */
 
 static int
 tree_dir_next_posix(struct tree *t);
@@ -767,9 +768,7 @@ _archive_read_next_header2(struct archive *_a, struct archive_entry *entry)
                a->entry_fd = -1;
        }
        t = a->tree;
-#if defined(HAVE_OPENAT) && defined(HAVE_FSTATAT) && defined(HAVE_FDOPENDIR)
-       t->flags |= needsChdir;
-#else
+#if !(defined(HAVE_OPENAT) && defined(HAVE_FSTATAT) && defined(HAVE_FDOPENDIR))
        /* Restore working directory. */
        tree_enter_working_dir(t);
 #endif
@@ -855,11 +854,9 @@ _archive_read_next_header2(struct archive *_a, struct archive_entry *entry)
 
 #if defined(HAVE_OPENAT) && defined(HAVE_FSTATAT) && defined(HAVE_FDOPENDIR)
        /* Restore working directory. */
-       if (t->flags & needsChdir) {
-               tree_enter_working_dir(t);
-               t->flags &= ~needsChdir;
-       }
+       tree_enter_working_dir(t);
 #endif
+
        /* Populate the archive_entry with metadata from the disk. */
        r = archive_read_disk_entry_from_file(&(a->archive), entry, -1, st);
 
@@ -1608,7 +1605,6 @@ tree_descent(struct tree *t)
                } else
                        close(t->working_dir_fd);
                t->working_dir_fd = new_fd;
-               t->flags |= needsChdir;
        }
 #else
        /* If it is a link, set up fd for the ascent. */
@@ -1647,18 +1643,15 @@ tree_ascend(struct tree *t)
        te = t->stack;
        prev_dir_fd = t->working_dir_fd;
 #if defined(HAVE_OPENAT) && defined(HAVE_FSTATAT) && defined(HAVE_FDOPENDIR)
-       if (te->flags & isDirLink) {
+       if (te->flags & isDirLink)
                t->working_dir_fd = te->symlink_parent_fd;
-               t->flags |= needsChdir;
-       } else {
+       else {
                int new_fd = openat(t->working_dir_fd, "..", O_RDONLY);
                if (new_fd < 0) {
                        t->tree_errno = errno;
                        r = TREE_ERROR_FATAL;
-               } else {
+               } else
                        t->working_dir_fd = new_fd;
-                       t->flags |= needsChdir;
-               }
        }
 #else
        if (te->flags & isDirLink) {
@@ -1694,9 +1687,14 @@ tree_ascend(struct tree *t)
 static int
 tree_enter_initial_dir(struct tree *t)
 {
-       if (t->initial_dir_fd >= 0)
-               return (fchdir(t->initial_dir_fd));
-       return (0);
+       int r = 0;
+
+       if (t->flags & onWorkingDir) {
+               r = fchdir(t->initial_dir_fd);
+               if (r == 0)
+                       t->flags &= ~onWorkingDir;
+       }
+       return (r);
 }
 
 /*
@@ -1705,9 +1703,19 @@ tree_enter_initial_dir(struct tree *t)
 static int
 tree_enter_working_dir(struct tree *t)
 {
-       if (t->working_dir_fd >= 0)
-               return (fchdir(t->working_dir_fd));
-       return (0);
+       int r = 0;
+
+       /*
+        * Change the current directory if really needed.
+        * Sometimes this is unneeded when we did not do
+        * descent.
+        */
+       if (t->depth > 0 && (t->flags & onWorkingDir) == 0) {
+               r = fchdir(t->working_dir_fd);
+               if (r == 0)
+                       t->flags |= onWorkingDir;
+       }
+       return (r);
 }
 
 static int