Thanks!
On Sat, Sep 17, 2005 at 10:14:43AM +1000, Rusty Russell wrote:
> # 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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