X-Git-Url: http://git.tuebingen.mpg.de/?p=paraslash.git;a=blobdiff_plain;f=afs.c;fp=afs.c;h=b15f83852e6919c4f0867065d13776c211416087;hp=6493586a6abad51c1f6bd5d3716c7a1dd1beeb23;hb=0b5c29fae8853bac16b91503df70b0e101dccca4;hpb=1f33eda05b3e96b32817a133287bcfc5e99ed6b4

diff --git a/afs.c b/afs.c
index 6493586a..b15f8385 100644
--- a/afs.c
+++ b/afs.c
@@ -728,6 +728,43 @@ err:
 	return ret;
 }
 
+/**
+ * Format and send an error message to the command handler.
+ *
+ * To pass an error message from the callback of an afs command to the client,
+ * this function should be called. It formats the message into a buffer which
+ * is passed as a shared memory area to the command handler from where it
+ * propagates to the client.
+ *
+ * The message will be tagged with the ERROR_LOG sideband designator so that
+ * the client writes it to its stderr stream rather than to stdout as with
+ * aca->pbout. In analogy to the default Unix semantics of stderr, the message
+ * is sent without buffering.
+ *
+ * If sending the error message fails, an error is logged on the server side,
+ * but no other action is taken.
+ *
+ * \param aca Used to obtain the fd to send the shmid to.
+ * \param fmt Usual format string.
+ */
+__printf_2_3 void afs_error(const struct afs_callback_arg *aca,
+		const char *fmt,...)
+{
+	va_list argp;
+	char *msg;
+	unsigned n;
+	int ret;
+
+	va_start(argp, fmt);
+	n = xvasprintf(&msg, fmt, argp);
+	va_end(argp);
+	ret = pass_buffer_as_shm(aca->fd, SBD_ERROR_LOG, msg, n + 1);
+	if (ret < 0)
+		PARA_ERROR_LOG("Could not send %s: %s\n", msg,
+			para_strerror(-ret));
+	free(msg);
+}
+
 static int call_callback(int fd, int query_shmid)
 {
 	void *query_shm;
@@ -958,12 +995,12 @@ static int com_select_callback(struct afs_callback_arg *aca)
 	/* ignore subsequent errors (but log them) */
 	if (current_mop && strcmp(current_mop, arg) != 0) {
 		int ret2;
-		para_printf(&aca->pbout, "switching back to %s\n", current_mop);
+		afs_error(aca, "switching back to %s\n", current_mop);
 		ret2 = activate_mood_or_playlist(current_mop, &aca->pbout);
 		if (ret2 >= 0)
 			goto free_lpr;
-		para_printf(&aca->pbout, "could not reactivate %s: %s\n",
-			current_mop, para_strerror(-ret2));
+		afs_error(aca, "could not reactivate %s: %s\n", current_mop,
+			para_strerror(-ret2));
 	}
 	activate_mood_or_playlist(NULL, &aca->pbout);
 free_lpr:
@@ -1001,8 +1038,7 @@ static int com_init_callback(struct afs_callback_arg *aca)
 			continue;
 		ret = t->ops->create(database_dir);
 		if (ret < 0) {
-			para_printf(&aca->pbout, "cannot create table %s\n",
-				t->name);
+			afs_error(aca, "cannot create table %s\n", t->name);
 			goto out;
 		}
 		para_printf(&aca->pbout, "successfully created %s table\n",
@@ -1010,7 +1046,7 @@ static int com_init_callback(struct afs_callback_arg *aca)
 	}
 	ret = open_afs_tables();
 	if (ret < 0)
-		para_printf(&aca->pbout, "cannot open afs tables: %s\n",
+		afs_error(aca, "cannot open afs tables: %s\n",
 			para_strerror(-ret));
 out:
 	return ret;