Attachment 6154 Details for Bug 7836 – Fix race in cups async printer services reload.

[patch] Fix race in cups async printer services reload.

async_printcap_svc_update.diff (text/plain), 6.99 KB, created by Lars Müller on 2010-12-20 02:48:01 UTC

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Creator: Lars Müller

Created: 2010-12-20 02:48:01 UTC

Size: 6.99 KB

patch

obsolete

>Index: source3/printing/print_cups.c
>===================================================================
>--- source3/printing/print_cups.c.orig
>+++ source3/printing/print_cups.c
>@@ -440,13 +440,19 @@ static bool cups_pcap_load_async(int *pf
> 	_exit(0);
> }
> 
>+struct cups_async_cb_args {
>+	int pipe_fd;
>+	void (*post_cache_fill_fn)(void);
>+};
>+
> static void cups_async_callback(struct event_context *event_ctx,
> 				struct fd_event *event,
> 				uint16 flags,
> 				void *p)
> {
> 	TALLOC_CTX *frame = talloc_stackframe();
>-	int fd = *(int *)p;
>+	struct cups_async_cb_args *cb_args = (struct cups_async_cb_args *)p;
>+	int fd = cb_args->pipe_fd;
> 	struct pcap_cache *tmp_pcap_cache = NULL;
> 
> 	DEBUG(5,("cups_async_callback: callback received for printer data. "
>@@ -540,27 +546,34 @@ static void cups_async_callback(struct e
> 
> 		/* And the systemwide pcap cache. */
> 		pcap_cache_replace(local_pcap_copy);
>+
>+		/* Caller may have requested post cache fill callback */
>+		if (cb_args->post_cache_fill_fn)
>+			cb_args->post_cache_fill_fn();
> 	} else {
> 		DEBUG(2,("cups_async_callback: failed to read a new "
> 			"printer list\n"));
> 	}
> 	close(fd);
>-	TALLOC_FREE(p);
>+	TALLOC_FREE(cb_args);
> 	TALLOC_FREE(cache_fd_event);
> }
> 
>-bool cups_cache_reload(void)
>+bool cups_cache_reload(void (*post_cache_fill_fn)(void))
> {
>-	int *p_pipe_fd = TALLOC_P(NULL, int);
>+	struct cups_async_cb_args *cb_args;
>+	int *p_pipe_fd;
> 
>-	if (!p_pipe_fd) {
>+	cb_args = TALLOC_P(NULL, struct cups_async_cb_args);
>+	if (!cb_args)
> 		return false;
>-	}
>-
>+	cb_args->post_cache_fill_fn = post_cache_fill_fn;
>+	p_pipe_fd = &cb_args->pipe_fd;
> 	*p_pipe_fd = -1;
> 
> 	/* Set up an async refresh. */
> 	if (!cups_pcap_load_async(p_pipe_fd)) {
>+		talloc_free(cb_args);
> 		return false;
> 	}
> 	if (!local_pcap_copy) {
>@@ -573,7 +586,7 @@ bool cups_cache_reload(void)
> 		cups_async_callback(smbd_event_context(),
> 					NULL,
> 					EVENT_FD_READ,
>-					(void *)p_pipe_fd);
>+					(void *)cb_args);
> 		if (!local_pcap_copy) {
> 			return false;
> 		}
>@@ -590,10 +603,10 @@ bool cups_cache_reload(void)
> 					NULL, *p_pipe_fd,
> 					EVENT_FD_READ,
> 					cups_async_callback,
>-					(void *)p_pipe_fd);
>+					(void *)cb_args);
> 		if (!cache_fd_event) {
> 			close(*p_pipe_fd);
>-			TALLOC_FREE(p_pipe_fd);
>+			talloc_free(cb_args);
> 			return false;
> 		}
> 	}
>Index: source3/printing/pcap.c
>===================================================================
>--- source3/printing/pcap.c.orig
>+++ source3/printing/pcap.c
>@@ -125,13 +125,14 @@ void pcap_cache_replace(const struct pca
> 	}
> }
> 
>-void pcap_cache_reload(void)
>+void pcap_cache_reload(void (*post_cache_fill_fn)(void))
> {
> 	const char *pcap_name = lp_printcapname();
> 	bool pcap_reloaded = False;
> 	struct pcap_cache *tmp_cache = NULL;
> 	XFILE *pcap_file;
> 	char *pcap_line;
>+	bool post_cache_fill_fn_handled = false;
> 
> 	DEBUG(3, ("reloading printcap cache\n"));
> 
>@@ -146,7 +147,12 @@ void pcap_cache_reload(void)
> 
> #ifdef HAVE_CUPS
> 	if (strequal(pcap_name, "cups")) {
>-		pcap_reloaded = cups_cache_reload();
>+		pcap_reloaded = cups_cache_reload(post_cache_fill_fn);
>+		/*
>+		 * cups_cache_reload() is async and calls post_cache_fill_fn()
>+		 * on successful completion
>+		 */
>+		post_cache_fill_fn_handled = true;
> 		goto done;
> 	}
> #endif
>@@ -244,6 +250,8 @@ done:
> 
> 	if (pcap_reloaded)
> 		pcap_cache_destroy_specific(&tmp_cache);
>+		if (post_cache_fill_fn_handled == false)
>+			post_cache_fill_fn();
> 	else {
> 		pcap_cache_destroy_specific(&pcap_cache);
> 		pcap_cache = tmp_cache;
>Index: source3/smbd/server.c
>===================================================================
>--- source3/smbd/server.c.orig
>+++ source3/smbd/server.c
>@@ -689,9 +689,9 @@ static void smbd_parent_loop(struct smbd
> /* NOTREACHED	return True; */
> }
> 
>-/****************************************************************************
>- Reload printers
>-**************************************************************************/
>+/***************************************************************************
>+purge stale printers and reload from pre-populated pcap cache
>+***************************************************************************/
> void reload_printers(void)
> {
> 	int snum;
>@@ -699,9 +699,9 @@ void reload_printers(void)
> 	int pnum = lp_servicenumber(PRINTERS_NAME);
> 	const char *pname;
> 
>-	pcap_cache_reload();
>+	SMB_ASSERT(pcap_cache_loaded());
> 
>-	/* remove stale printers */
>+	DEBUG(10, ("reloading printer services from pcap cache\n"));
> 	for (snum = 0; snum < n_services; snum++) {
> 		/* avoid removing PRINTERS_NAME or non-autoloaded printers */
> 		if (snum == pnum || !(lp_snum_ok(snum) && lp_print_ok(snum) &&
>@@ -748,7 +748,7 @@ bool reload_services(bool test)
> 
> 	ret = lp_load(get_dyn_CONFIGFILE(), False, False, True, True);
> 
>-	reload_printers();
>+	pcap_cache_reload(&reload_printers);
> 
> 	/* perhaps the config filename is now set */
> 	if (!test)
>Index: source3/printing/load.c
>===================================================================
>--- source3/printing/load.c.orig
>+++ source3/printing/load.c
>@@ -53,12 +53,11 @@ static void add_auto_printers(void)
> }
> 
> /***************************************************************************
>-load automatic printer services
>+load automatic printer services from pre-populated pcap cache
> ***************************************************************************/
> void load_printers(void)
> {
>-	if (!pcap_cache_loaded())
>-		pcap_cache_reload();
>+	SMB_ASSERT(pcap_cache_loaded());
> 
> 	add_auto_printers();
> 
>Index: source3/include/proto.h
>===================================================================
>--- source3/include/proto.h.orig
>+++ source3/include/proto.h
>@@ -4870,7 +4870,7 @@ void pcap_cache_destroy_specific(struct
> bool pcap_cache_add(const char *name, const char *comment);
> bool pcap_cache_loaded(void);
> void pcap_cache_replace(const struct pcap_cache *cache);
>-void pcap_cache_reload(void);
>+void pcap_cache_reload(void (*post_cache_fill_fn)(void));
> bool pcap_printername_ok(const char *printername);
> void pcap_printer_fn_specific(const struct pcap_cache *, void (*fn)(const char *, const char *, void *), void *);
> void pcap_printer_fn(void (*fn)(const char *, const char *, void *), void *);
>@@ -4881,7 +4881,7 @@ bool aix_cache_reload(void);
> 
> /* The following definitions come from printing/print_cups.c  */
> 
>-bool cups_cache_reload(void);
>+bool cups_cache_reload(void (*post_cache_fill_fn)(void));
> bool cups_pull_comment_location(NT_PRINTER_INFO_LEVEL_2 *printer);
> 
> /* The following definitions come from printing/print_generic.c  */
>Index: source3/web/swat.c
>===================================================================
>--- source3/web/swat.c.orig
>+++ source3/web/swat.c
>@@ -490,7 +490,7 @@ static int save_reload(int snum)
>                 return 0;
>         }
> 	iNumNonAutoPrintServices = lp_numservices();
>-	load_printers();
>+	pcap_cache_reload(&load_printers);
> 
> 	return 1;
> }
>@@ -1434,7 +1434,7 @@ const char *lang_msg_rotate(TALLOC_CTX *
> 	load_config(True);
> 	load_interfaces();
> 	iNumNonAutoPrintServices = lp_numservices();
>-	load_printers();
>+	pcap_cache_reload(&load_printers);
> 
> 	cgi_setup(get_dyn_SWATDIR(), !demo_mode);
>

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