# HG changeset patch
# User Rusty Russell <rusty@xxxxxxxxxxxxxxx>
# Node ID 90b4e122d3407c7d0e28e6391ca89d46d5a81e52
# Parent fd19e760932d095b23d38e67eaec24dd02ba3aba
Make xs_mkdir an xs_rm idempotent.
When modifying libxenstore to transparently restart when the daemon dies,
it became apparent that life is simpler when all commands can simply be
restarted. So this patch makes a slight semantic change to xs_rm and xs_mkdir:
xs_rm now succeeds if the file doesn't exist (as long as the parent exists),
and xs_mkdir succeeds if the directory already exists.
Noone should notice.
Signed-off-by: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
diff -r fd19e760932d -r 90b4e122d340 tools/xenstore/testsuite/02directory.test
--- a/tools/xenstore/testsuite/02directory.test Thu Sep 15 19:46:14 2005
+++ b/tools/xenstore/testsuite/02directory.test Fri Sep 16 05:01:11 2005
@@ -27,10 +27,8 @@
expect contents2
read /dir/test2
-# Creating dir over the top should fail.
-expect mkdir failed: File exists
+# Creating dir over the top should succeed.
mkdir /dir
-expect mkdir failed: File exists
mkdir /dir/test2
# Mkdir implicitly creates directories.
diff -r fd19e760932d -r 90b4e122d340 tools/xenstore/testsuite/04rm.test
--- a/tools/xenstore/testsuite/04rm.test Thu Sep 15 19:46:14 2005
+++ b/tools/xenstore/testsuite/04rm.test Fri Sep 16 05:01:11 2005
@@ -1,5 +1,4 @@
-# Remove non-existant fails.
-expect rm failed: No such file or directory
+# Remove non-existant is OK, as long as parent exists
rm /test
expect rm failed: No such file or directory
rm /dir/test
diff -r fd19e760932d -r 90b4e122d340 tools/xenstore/xenstored_core.c
--- a/tools/xenstore/xenstored_core.c Thu Sep 15 19:46:14 2005
+++ b/tools/xenstore/xenstored_core.c Fri Sep 16 05:01:11 2005
@@ -961,6 +961,13 @@
return dir;
}
+static bool node_exists(struct connection *conn, const char *node)
+{
+ struct stat st;
+
+ return lstat(node_dir(conn->transaction, node), &st) == 0;
+}
+
/* path, flags, data... */
static void do_write(struct connection *conn, struct buffered_data *in)
{
@@ -1050,7 +1057,6 @@
static void do_mkdir(struct connection *conn, const char *node)
{
char *dir;
- struct stat st;
node = canonicalize(conn, node);
if (!check_node_perms(conn, node, XS_PERM_WRITE|XS_PERM_ENOENT_OK)) {
@@ -1066,9 +1072,9 @@
if (transaction_block(conn, node))
return;
- /* Must not already exist. */
- if (lstat(node_dir(conn->transaction, node), &st) == 0) {
- send_error(conn, EEXIST);
+ /* If it already exists, fine. */
+ if (node_exists(conn, node)) {
+ send_ack(conn, XS_MKDIR);
return;
}
@@ -1089,6 +1095,15 @@
node = canonicalize(conn, node);
if (!check_node_perms(conn, node, XS_PERM_WRITE)) {
+ /* Didn't exist already? Fine, if parent exists. */
+ if (errno == ENOENT) {
+ if (node_exists(conn, get_parent(node))) {
+ send_ack(conn, XS_RM);
+ return;
+ }
+ /* Restore errno, just in case. */
+ errno = ENOENT;
+ }
send_error(conn, errno);
return;
}
diff -r fd19e760932d -r 90b4e122d340 tools/xenstore/xs.c
--- a/tools/xenstore/xs.c Thu Sep 15 19:46:14 2005
+++ b/tools/xenstore/xs.c Fri Sep 16 05:01:11 2005
@@ -357,7 +357,7 @@
}
/* Create a new directory.
- * Returns false on failure.
+ * Returns false on failure, or success if it already exists.
*/
bool xs_mkdir(struct xs_handle *h, const char *path)
{
@@ -365,7 +365,7 @@
}
/* Destroy a file or directory (directories must be empty).
- * Returns false on failure.
+ * Returns false on failure, or success if it doesn't exist.
*/
bool xs_rm(struct xs_handle *h, const char *path)
{
diff -r fd19e760932d -r 90b4e122d340 tools/xenstore/xs.h
--- a/tools/xenstore/xs.h Thu Sep 15 19:46:14 2005
+++ b/tools/xenstore/xs.h Fri Sep 16 05:01:11 2005
@@ -59,12 +59,12 @@
unsigned int len, int createflags);
/* Create a new directory.
- * Returns false on failure.
+ * Returns false on failure, or success if it already exists.
*/
bool xs_mkdir(struct xs_handle *h, const char *path);
/* Destroy a file or directory (and children).
- * Returns false on failure.
+ * Returns false on failure, or success if it doesn't exist.
*/
bool xs_rm(struct xs_handle *h, const char *path);
diff -r fd19e760932d -r 90b4e122d340 tools/xenstore/xs_random.c
--- a/tools/xenstore/xs_random.c Thu Sep 15 19:46:14 2005
+++ b/tools/xenstore/xs_random.c Fri Sep 16 05:01:11 2005
@@ -385,7 +385,7 @@
make_dirs(parent_filename(dirname));
if (mkdir(dirname, 0700) != 0)
- return false;
+ return (errno == EEXIST);
init_perms(dirname);
return true;
@@ -401,8 +401,11 @@
return false;
}
- if (lstat(filename, &st) != 0)
- return false;
+ if (lstat(filename, &st) != 0) {
+ if (lstat(parent_filename(filename), &st) != 0)
+ return false;
+ return true;
+ }
if (!write_ok(info, path))
return false;
--
A bad analogy is like a leaky screwdriver -- Richard Braakman
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