[v3,31/33] tools/xenstored: add helpers for filename handling

Commit Message

Jürgen Groß Jan. 4, 2024, 9 a.m. UTC

Add some helpers for handling filenames which might need different
implementations between stubdom and daemon environments:

- expansion of relative filenames (those are not really defined today,
  just expand them to be relative to /var/lib/xen/xenstore)
- expansion of xenstore_daemon_rundir() (used e.g. for saving the state
  file in case of live update - needs to be unchanged in the daemon
  case, but should result in /var/lib/xen/xenstore for stubdom)

Signed-off-by: Juergen Gross <[e-mail]>
Reviewed-by: Jason Andryuk <[e-mail]>
---
V3:
- make absolute_filename() return a pointer to const (Julien Grall)
---
 tools/xenstored/core.c      | 15 +++++++++++++--
 tools/xenstored/core.h      |  5 ++++-
 tools/xenstored/lu_daemon.c |  4 ++--
 tools/xenstored/minios.c    |  5 +++++
 tools/xenstored/posix.c     |  8 +++++++-
 5 files changed, 31 insertions(+), 6 deletions(-)

Comments

Julien Grall Jan. 26, 2024, 5:27 p.m. UTC | #1

Hi Juergen,

On 04/01/2024 09:00, Juergen Gross wrote:
> Add some helpers for handling filenames which might need different
> implementations between stubdom and daemon environments:
> 
> - expansion of relative filenames (those are not really defined today,
>    just expand them to be relative to /var/lib/xen/xenstore)
> - expansion of xenstore_daemon_rundir() (used e.g. for saving the state
>    file in case of live update - needs to be unchanged in the daemon
>    case, but should result in /var/lib/xen/xenstore for stubdom)
> 
> Signed-off-by: Juergen Gross <[e-mail]>
> Reviewed-by: Jason Andryuk <[e-mail]>

Reviewed-by: Julien Grall <[e-mail]>

Cheers,

Patch

diff --git a/tools/xenstored/core.c b/tools/xenstored/core.c
index b648af16fa..711be878dc 100644
--- a/tools/xenstored/core.c
+++ b/tools/xenstored/core.c
@@ -65,7 +65,7 @@  char **orig_argv;
 LIST_HEAD(connections);
 int tracefd = -1;
 bool keep_orphans = false;
-char *tracefile = NULL;
+const char *tracefile = NULL;
 static struct hashtable *nodes;
 unsigned int trace_flags = TRACE_OBJ | TRACE_IO;
 
@@ -139,6 +139,17 @@  void trace_destroy(const void *data, const char *type)
 		trace("obj: DESTROY %s %p\n", type, data);
 }
 
+/*
+ * Return an absolute filename.
+ * In case of a relative filename given as input, prepend XENSTORE_LIB_DIR.
+ */
+const char *absolute_filename(const void *ctx, const char *filename)
+{
+	if (filename[0] != '/')
+		return talloc_asprintf(ctx, XENSTORE_LIB_DIR "/%s", filename);
+	return talloc_strdup(ctx, filename);
+}
+
 void close_log(void)
 {
 	if (tracefd >= 0)
@@ -2761,7 +2772,7 @@  int main(int argc, char *argv[])
 #endif
 
 	if (tracefile)
-		tracefile = talloc_strdup(NULL, tracefile);
+		tracefile = absolute_filename(NULL, tracefile);
 
 #ifndef NO_LIVE_UPDATE
 	/* Read state in case of live update. */
diff --git a/tools/xenstored/core.h b/tools/xenstored/core.h
index 0cb3a272b5..9a5615fcbe 100644
--- a/tools/xenstored/core.h
+++ b/tools/xenstored/core.h
@@ -343,7 +343,7 @@  extern int sock;
 extern int orig_argc;
 extern char **orig_argv;
 
-extern char *tracefile;
+extern const char *tracefile;
 extern int tracefd;
 
 /* Trace flag values must be kept in sync with trace_switches[] contents. */
@@ -404,6 +404,9 @@  void handle_special_fds(void);
 void mount_9pfs(void);
 #endif
 
+const char *xenstore_rundir(void);
+const char *absolute_filename(const void *ctx, const char *filename);
+
 /* Close stdin/stdout/stderr to complete daemonize */
 void finish_daemonize(void);
 
diff --git a/tools/xenstored/lu_daemon.c b/tools/xenstored/lu_daemon.c
index 71bcabadd3..6351111ab0 100644
--- a/tools/xenstored/lu_daemon.c
+++ b/tools/xenstored/lu_daemon.c
@@ -24,7 +24,7 @@  void lu_get_dump_state(struct lu_dump_state *state)
 	state->size = 0;
 
 	state->filename = talloc_asprintf(NULL, "%s/state_dump",
-					  xenstore_daemon_rundir());
+					  xenstore_rundir());
 	if (!state->filename)
 		barf("Allocation failure");
 
@@ -65,7 +65,7 @@  FILE *lu_dump_open(const void *ctx)
 	int fd;
 
 	filename = talloc_asprintf(ctx, "%s/state_dump",
-				   xenstore_daemon_rundir());
+				   xenstore_rundir());
 	if (!filename)
 		return NULL;
 
diff --git a/tools/xenstored/minios.c b/tools/xenstored/minios.c
index 10e1765f8d..24fc3150b7 100644
--- a/tools/xenstored/minios.c
+++ b/tools/xenstored/minios.c
@@ -119,3 +119,8 @@  void mount_9pfs(void)
 {
 	create_thread("mount-9pfs", mount_thread, NULL);
 }
+
+const char *xenstore_rundir(void)
+{
+	return XENSTORE_LIB_DIR;
+}
diff --git a/tools/xenstored/posix.c b/tools/xenstored/posix.c
index f72c8406d2..ad6e874c1e 100644
--- a/tools/xenstored/posix.c
+++ b/tools/xenstored/posix.c
@@ -325,9 +325,10 @@  void early_init(bool live_update, bool dofork, const char *pidfile)
 {
 	reopen_log();
 
-	/* Make sure xenstored directory exists. */
+	/* Make sure xenstored directories exist. */
 	/* Errors ignored here, will be reported when we open files */
 	mkdir(xenstore_daemon_rundir(), 0755);
+	mkdir(XENSTORE_LIB_DIR, 0755);
 
 	if (dofork) {
 		openlog("xenstored", 0, LOG_DAEMON);
@@ -394,3 +395,8 @@  void late_init(bool live_update)
 	}
 #endif
 }
+
+const char *xenstore_rundir(void)
+{
+	return xenstore_daemon_rundir();
+}