X-Git-Url: http://git.tdb.fi/?p=pmount-gui.git;a=blobdiff_plain;f=main.c;h=ae08cbb7cda87de794b03d673e40a6de691e721e;hp=ee51767f7a81db07984d50e37cd0be650a9b1377;hb=a76de4d866743180e75f51088dd6d1407dcded9f;hpb=1f257c6ced9b6eab932a4801899c3aa7a92e219f

diff --git a/main.c b/main.c
index ee51767..ae08cbb 100644
--- a/main.c
+++ b/main.c
@@ -29,7 +29,12 @@ typedef struct sDevice
 } Device;
 
 int verbosity = 0;
+char *post_mount_command = NULL;
 
+/**
+Parses a string of the form name=value and places the components in a Property
+structure.  Returns 0 on success, or -1 if the string wasn't a valid property.
+*/
 int parse_property(char *str, int size, Property *prop)
 {
 	int equals = -1;
@@ -53,16 +58,28 @@ int parse_property(char *str, int size, Property *prop)
 	return 0;
 }
 
+/**
+Retrieves all properties associated with a /dev node.  The returned array is
+terminated with an entry containing NULL values.  Use free_properties to free
+the array.
+*/
 Property *get_device_properties(char *node)
 {
 	int pid;
 	int pipe_fd[2];
+	char *buf;
+	int bufsize;
+	int pos = 0;
+	int eof = 0;
+	Property *props = NULL;
+	int n_props = 0;
 
 	pipe(pipe_fd);
 
 	pid = fork();
 	if(pid==0)
 	{
+		/* Child process */
 		if(verbosity>=2)
 			printf("Running udevadm info -q property -n \"%s\"\n", node);
 
@@ -72,87 +89,88 @@ Property *get_device_properties(char *node)
 		execl("/sbin/udevadm", "udevadm", "info", "-q", "property", "-n", node, NULL);
 		_exit(1);
 	}
-	else if(pid>0)
+	else if(pid<0)
 	{
-		char *buf;
-		int bufsize;
-		int pos = 0;
-		int eof = 0;
-		Property *props = NULL;
-		int n_props = 0;
-
+		close(pipe_fd[0]);
 		close(pipe_fd[1]);
 
-		bufsize = 256;
-		buf = (char *)malloc(bufsize);
-
-		while(1)
-		{
-			int newline;
-			int i;
-			Property prop;
+		return NULL;
+	}
 
-			if(!eof)
-			{
-				int len;
-
-				len = read(pipe_fd[0], buf+pos, bufsize-pos);
-				if(len==0)
-					eof = 1;
-				else if(len==-1)
-					break;
-				pos += len;
-			}
+	/* Parent process */
+	close(pipe_fd[1]);
 
-			newline = -1;
-			for(i=0; (newline<0 && i<pos); ++i)
-				if(buf[i]=='\n')
-					newline = i;
+	bufsize = 256;
+	buf = (char *)malloc(bufsize);
 
-			if(newline<0)
-			{
-				if(eof)
-					break;
-				bufsize *= 2;
-				buf = (char *)realloc(buf, bufsize);
-				continue;
-			}
+	while(1)
+	{
+		int newline;
+		int i;
+		Property prop;
 
-			if(parse_property(buf, newline, &prop)==0)
-			{
-				props = (Property *)realloc(props, (n_props+2)*sizeof(Property));
-				props[n_props] = prop;
-				++n_props;
+		if(!eof)
+		{
+			int len;
 
-				memmove(buf, buf+newline+1, pos-newline-1);
-				pos -= newline+1;
-			}
-			else
+			len = read(pipe_fd[0], buf+pos, bufsize-pos);
+			if(len==0)
+				eof = 1;
+			else if(len==-1)
 				break;
+			pos += len;
 		}
 
-		free(buf);
+		newline = -1;
+		for(i=0; (newline<0 && i<pos); ++i)
+			if(buf[i]=='\n')
+				newline = i;
 
-		if(props)
+		if(newline<0)
 		{
-			props[n_props].name = NULL;
-			props[n_props].value = NULL;
+			if(eof)
+				break;
+
+			/* There was no newline in the buffer but there is more output to
+			be read.  Try again with a larger buffer. */
+			bufsize *= 2;
+			buf = (char *)realloc(buf, bufsize);
+			continue;
 		}
 
-		waitpid(pid, NULL, 0);
-		close(pipe_fd[0]);
+		if(parse_property(buf, newline, &prop)==0)
+		{
+			/* Reserve space for a sentinel value as well. */
+			props = (Property *)realloc(props, (n_props+2)*sizeof(Property));
+			props[n_props] = prop;
+			++n_props;
 
-		return props;
+			memmove(buf, buf+newline+1, pos-newline-1);
+			pos -= newline+1;
+		}
+		else
+			break;
 	}
-	else
-	{
-		close(pipe_fd[0]);
-		close(pipe_fd[1]);
 
-		return NULL;
+	free(buf);
+
+	if(props)
+	{
+		/* Terminate the array with NULL pointers. */
+		props[n_props].name = NULL;
+		props[n_props].value = NULL;
 	}
+
+	waitpid(pid, NULL, 0);
+	close(pipe_fd[0]);
+
+	return props;
 }
 
+/**
+Looks for a property in an array of properties and returns its value.  Returns
+NULL if the property was not found.
+*/
 char *get_property_value(Property *props, char *name)
 {
 	int i;
@@ -162,6 +180,10 @@ char *get_property_value(Property *props, char *name)
 	return NULL;
 }
 
+/**
+Checks if a property has a specific value.  A NULL value is matched if the
+property does not exist.
+*/
 int match_property_value(Property *props, char *name, char *value)
 {
 	char *v = get_property_value(props, name);
@@ -170,6 +192,9 @@ int match_property_value(Property *props, char *name, char *value)
 	return strcmp(v, value)==0;
 }
 
+/**
+Frees an array of properties and all strings contained in it.
+*/
 void free_properties(Property *props)
 {
 	int i;
@@ -183,6 +208,9 @@ void free_properties(Property *props)
 	free(props);
 }
 
+/**
+Reads device names from an fstab/mtab file.
+*/
 char **get_mount_entries(char *filename, int (*predicate)(struct mntent *))
 {
 	FILE *file;
@@ -209,42 +237,60 @@ char **get_mount_entries(char *filename, int (*predicate)(struct mntent *))
 	return devices;
 }
 
+/**
+Returns an array of all currently mounted devices.
+*/
 char **get_mounted_devices(void)
 {
 	return get_mount_entries("/etc/mtab", NULL);
 }
 
+/**
+Checks if an fstab entry has the user option set.
+*/
 int is_user_mountable(struct mntent *me)
 {
 	return hasmntopt(me, "user")!=NULL;
 }
 
+/**
+Returns an array of user-mountable devices listed in fstab.
+*/
 char **get_fstab_devices(void)
 {
 	return get_mount_entries("/etc/fstab", &is_user_mountable);
 }
 
-int is_in_array(char **names, char *devname)
+/**
+Checks if an array of strings contains the specified string.
+*/
+int is_in_array(char **array, char *str)
 {
 	int i;
-	if(!names || !devname)
+	if(!array || !str)
 		return 0;
-	for(i=0; names[i]; ++i)
-		if(!strcmp(devname, names[i]))
+	for(i=0; array[i]; ++i)
+		if(!strcmp(str, array[i]))
 			return 1;
 	return 0;
 }
 
-void free_device_names(char **names)
+/**
+Frees an array of strings.
+*/
+void free_string_array(char **array)
 {
 	int i;
-	if(!names)
+	if(!array)
 		return;
-	for(i=0; names[i]; ++i)
-		free(names[i]);
-	free(names);
+	for(i=0; array[i]; ++i)
+		free(array[i]);
+	free(array);
 }
 
+/**
+Checks if a partition identified by a sysfs path is on a removable device.
+*/
 int is_removable(char *devpath)
 {
 	char fnbuf[256];
@@ -253,11 +299,15 @@ int is_removable(char *devpath)
 	int fd;
 
 	len = snprintf(fnbuf, sizeof(fnbuf), "/sys%s", devpath);
+	/* Default to not removable if the path was too long. */
 	if(len+10>=(int)sizeof(fnbuf))
 		return 0;
 
+	/* We got a partition as a parameter, but the removable property is on the
+	disk.  Replace the last component with "removable". */
 	for(ptr=fnbuf+len; (ptr>fnbuf && *ptr!='/'); --ptr) ;
 	strcpy(ptr, "/removable");
+
 	fd = open(fnbuf, O_RDONLY);
 	if(fd!=-1)
 	{
@@ -277,6 +327,11 @@ int is_removable(char *devpath)
 	return 0;
 }
 
+/**
+Checks if a partition's disk or any of its parent devices are connected to any
+of a set of buses.  The device is identified by a sysfs path.  The bus array
+must be terminated with a NULL entry.
+*/
 int check_buses(char *devpath, char **buses)
 {
 	char fnbuf[256];
@@ -284,6 +339,7 @@ int check_buses(char *devpath, char **buses)
 	int len;
 
 	len = snprintf(fnbuf, sizeof(fnbuf), "/sys%s", devpath);
+	/* Default to no match if the path was too long. */
 	if(len+10>=(int)sizeof(fnbuf))
 		return 0;
 
@@ -291,26 +347,35 @@ int check_buses(char *devpath, char **buses)
 		if(*ptr=='/')
 		{
 			char linkbuf[256];
+			/* Replace the last component with "subsystem". */
 			strcpy(ptr, "/subsystem");
 			len = readlink(fnbuf, linkbuf, sizeof(linkbuf)-1);
-			*ptr = 0;
 
 			if(len!=-1)
 			{
-				int i;
 				linkbuf[len] = 0;
+				/* Extract the last component of the subsystem symlink. */
 				for(; (len>0 && linkbuf[len-1]!='/'); --len) ;
+
 				if(verbosity>=2)
+				{
+					*ptr = 0;
 					printf("  Subsystem of %s is %s\n", fnbuf, linkbuf+len);
-				for(i=0; buses[i]; ++i)
-					if(strcmp(linkbuf+len, buses[i])==0)
-						return 1;
+				}
+
+				if(is_in_array(buses, linkbuf+len))
+					return 1;
 			}
 		}
 
 	return 0;
 }
 
+/**
+Check if an array of properties describes a device that can be mounted.  An
+array of explicitly allowed devices can be passed in as well.  Both arrays must
+be terminated by a NULL entry.
+*/
 int can_mount(Property *props, char **allowed)
 {
 	static char *removable_buses[] = { "usb", "firewire", 0 };
@@ -322,9 +387,12 @@ int can_mount(Property *props, char **allowed)
 	if(is_in_array(allowed, devname))
 		return 1;
 
+	/* Special case for CD devices, since they are not partitions.  Only allow
+	mounting if media is inserted. */
 	if(match_property_value(props, "ID_TYPE", "cd") && match_property_value(props, "ID_CDROM_MEDIA", "1"))
 		return 1;
 
+	/* Only allow mounting partitions. */
 	if(!match_property_value(props, "DEVTYPE", "partition"))
 		return 0;
 
@@ -332,6 +400,9 @@ int can_mount(Property *props, char **allowed)
 	if(is_removable(devpath))
 		return 1;
 
+	/* Certain buses are removable by nature, but devices only advertise
+	themselves as removable if they support removable media, e.g. memory card
+	readers. */
 	bus = get_property_value(props, "ID_BUS");
 	if(is_in_array(removable_buses, bus))
 		return 1;
@@ -339,6 +410,10 @@ int can_mount(Property *props, char **allowed)
 	return check_buses(devpath, removable_buses);
 }
 
+/**
+Returns an array of all device nodes in a directory.  Symbolic links are
+dereferenced.
+*/
 char **get_device_nodes(char *dirname)
 {
 	DIR *dir;
@@ -361,6 +436,7 @@ char **get_device_nodes(char *dirname)
 		char *node;
 		int duplicate = 0;
 
+		/* Ignore . and .. entries. */
 		if(de->d_name[0]=='.' && (de->d_name[1]==0 || (de->d_name[1]=='.' && de->d_name[2]==0)))
 			continue;
 
@@ -379,6 +455,8 @@ char **get_device_nodes(char *dirname)
 			}
 		}
 
+		/* There may be multiple symlinks to the same device.  Only include each
+		device once in the returned array. */
 		if(checked)
 		{
 			for(i=0; (!duplicate && i<n_checked); ++i)
@@ -415,6 +493,7 @@ char **get_device_nodes(char *dirname)
 	return nodes;
 }
 
+/** Returns an array of all mountable devices. */
 Device *get_devices(void)
 {
 	char **nodes = NULL;
@@ -465,6 +544,8 @@ Device *get_devices(void)
 
 			devname = get_property_value(props, "DEVNAME");
 
+			/* Get a human-readable label for the device.  Use filesystem label,
+			filesystem UUID or device node name in order of preference. */
 			label = get_property_value(props, "ID_FS_LABEL");
 			if(!label)
 				label = get_property_value(props, "ID_FS_UUID");
@@ -487,6 +568,7 @@ Device *get_devices(void)
 
 			stat(nodes[i], &st);
 
+			/* Reserve space for a sentinel entry. */
 			devices = (Device *)realloc(devices, (n_devices+2)*sizeof(Device));
 			devices[n_devices].node = nodes[i];
 			devices[n_devices].label = strdup(label);
@@ -501,10 +583,11 @@ Device *get_devices(void)
 	}
 
 	free(nodes);
-	free_device_names(mounted);
+	free_string_array(mounted);
 
 	if(devices)
 	{
+		/* Terminate the array with NULL pointers. */
 		devices[n_devices].node = NULL;
 		devices[n_devices].label = NULL;
 		devices[n_devices].description = NULL;
@@ -513,6 +596,9 @@ Device *get_devices(void)
 	return devices;
 }
 
+/**
+Frees an array of devices and all strings contained in it.
+*/
 void free_devices(Device *devices)
 {
 	int i;
@@ -527,116 +613,168 @@ void free_devices(Device *devices)
 	free(devices);
 }
 
+/**
+Callback for activating a row in the device list.  Mounts or unmounts the
+device depending on operating mode.
+*/
 void row_activated(GtkTreeView *list, GtkTreePath *path, GtkTreeViewColumn *column, gpointer user_data)
 {
 	GtkTreeModel *model;
 	GtkTreeIter iter;
 	int umount = *(int *)user_data;
+	char buf[1024];
+	int pos = 0;
+	int status = 0;
+	fd_set fds;
+	struct timeval timeout;
+	Device *device;
+	int pid;
+	int pipe_fd[2];
 
 	model = gtk_tree_view_get_model(list);
 
-	if(gtk_tree_model_get_iter(model, &iter, path))
-	{
-		Device *device;
-		int pid;
-		int pipe_fd[2];
+	if(!gtk_tree_model_get_iter(model, &iter, path))
+		return;
 
-		gtk_tree_model_get(model, &iter, 1, &device, -1);
+	gtk_tree_model_get(model, &iter, 1, &device, -1);
 
-		pipe(pipe_fd);
+	pipe(pipe_fd);
 
-		pid = fork();
-		if(pid==0)
+	pid = fork();
+	if(pid==0)
+	{
+		/* Child process */
+		if(verbosity>=1)
 		{
-			if(verbosity>=1)
-			{
-				if(umount)
-					printf("Running pumount %s\n", device->node);
-				else
-					printf("Running pmount %s %s\n", device->node, device->label);
-			}
-
-			close(pipe_fd[0]);
-			dup2(pipe_fd[1], 1);
-			dup2(pipe_fd[1], 2);
-
 			if(umount)
-				execl("/usr/bin/pumount", "pumount", device->node, NULL);
+				printf("Running pumount %s\n", device->node);
 			else
-				execl("/usr/bin/pmount", "pmount", device->node, device->label, NULL);
-			_exit(1);
+				printf("Running pmount %s %s\n", device->node, device->label);
 		}
-		else if(pid>0)
-		{
-			char buf[1024];
-			int pos = 0;
-			int status = 0;
-			fd_set fds;
-			struct timeval timeout;
-
-			close(pipe_fd[1]);
-			FD_ZERO(&fds);
-			FD_SET(pipe_fd[0], &fds);
-			timeout.tv_sec = 0;
-			timeout.tv_usec = 200000;
-
-			while(1)
-			{
-				if(select(pipe_fd[0]+1, &fds, NULL, NULL, &timeout))
-				{
-					int len;
 
-					len = read(pipe_fd[0], buf+pos, sizeof(buf)-pos-1);
-					if(len<=0)
-						break;
-					pos += len;
-				}
-				else if(waitpid(pid, &status, 0))
-				{
-					pid = 0;
-					break;
-				}
-			}
+		close(pipe_fd[0]);
+		dup2(pipe_fd[1], 1);
+		dup2(pipe_fd[1], 2);
 
-			if(pid)
-				waitpid(pid, &status, 0);
+		if(umount)
+			execl("/usr/bin/pumount", "pumount", device->node, NULL);
+		else
+			execl("/usr/bin/pmount", "pmount", device->node, device->label, NULL);
+		_exit(1);
+	}
+	else if(pid<0)
+		return;
 
-			buf[pos] = 0;
+	/* Parent process */
 
-			if(verbosity>=1)
-			{
-				if(WIFEXITED(status))
-				{
-					if(WEXITSTATUS(status))
-						printf("Command exited successfully\n");
-					else
-						printf("Command exited with status %d\n", WEXITSTATUS(status));
-				}
-				else if(WIFSIGNALED(status))
-					printf("Command terminated with signal %d\n", WTERMSIG(status));
-				else
-					printf("Command exited with unknown result %04X\n", status);
-			}
+	close(pipe_fd[1]);
+	FD_ZERO(&fds);
+	FD_SET(pipe_fd[0], &fds);
+	timeout.tv_sec = 0;
+	timeout.tv_usec = 200000;
 
-			if(!WIFEXITED(status) || WEXITSTATUS(status))
-			{
-				GtkWidget *dialog;
+	while(1)
+	{
+		/* The write fd for the pipe may be inherited by a fuse server
+		process and stay open indefinitely. */
+		if(select(pipe_fd[0]+1, &fds, NULL, NULL, &timeout))
+		{
+			int len;
 
-				dialog = gtk_message_dialog_new(NULL, 0, GTK_MESSAGE_ERROR, GTK_BUTTONS_OK, "%s", buf);
-				g_signal_connect(dialog, "response", &gtk_main_quit, NULL);
-				gtk_widget_show_all(dialog);
-			}
+			len = read(pipe_fd[0], buf+pos, sizeof(buf)-pos-1);
+			if(len<=0)
+				break;
+			pos += len;
+		}
+		else if(waitpid(pid, &status, 0))
+		{
+			pid = 0;
+			break;
+		}
+	}
+
+	close(pipe_fd[0]);
+	if(pid)
+		waitpid(pid, &status, 0);
+
+	buf[pos] = 0;
+
+	if(verbosity>=1)
+	{
+		if(WIFEXITED(status))
+		{
+			if(WEXITSTATUS(status))
+				printf("Command exited successfully\n");
 			else
-				gtk_main_quit();
+				printf("Command exited with status %d\n", WEXITSTATUS(status));
 		}
+		else if(WIFSIGNALED(status))
+			printf("Command terminated with signal %d\n", WTERMSIG(status));
 		else
+			printf("Command exited with unknown result %04X\n", status);
+	}
+
+	if(!WIFEXITED(status) || WEXITSTATUS(status))
+	{
+		GtkWidget *dialog;
+
+		/* Pmount terminated with nonzero status or a signal.  Display an
+		error to the user. */
+		dialog = gtk_message_dialog_new(NULL, 0, GTK_MESSAGE_ERROR, GTK_BUTTONS_OK, "%s", buf);
+		g_signal_connect(dialog, "response", &gtk_main_quit, NULL);
+		gtk_widget_show_all(dialog);
+		return;
+	}
+
+	gtk_main_quit();
+
+	if(post_mount_command && !umount)
+	{
+		char workdir[256];
+		int len;
+		len = snprintf(workdir, sizeof(workdir), "/media/%s", device->label);
+		if(len<(int)sizeof(workdir))
 		{
+			if(verbosity>=1)
+				printf("Running %s in %s\n", post_mount_command, workdir);
+
+			pid = fork();
+			if(pid==0)
+			{
+				chdir(workdir);
+				execlp(post_mount_command, post_mount_command, NULL);
+				_exit(1);
+			}
 		}
 	}
 
 	(void)column;
 }
 
+/**
+Callback for the mount/unmount button.  Causes the selected row in the device
+list to be activated.
+*/
+void button_clicked(GtkButton *button, gpointer user_data)
+{
+	GtkWidget *list = (GtkWidget *)user_data;
+	GtkTreeSelection *selection;
+	GtkTreeIter iter;
+	GtkTreeModel *model;
+	GtkTreePath *path;
+
+	selection = gtk_tree_view_get_selection(GTK_TREE_VIEW(list));
+	gtk_tree_selection_get_selected(selection, &model, &iter);
+	path = gtk_tree_model_get_path(model, &iter);
+	gtk_tree_view_row_activated(GTK_TREE_VIEW(list), path, gtk_tree_view_get_column(GTK_TREE_VIEW(list), 0));
+	gtk_tree_path_free(path);
+
+	(void)button;
+}
+
+/**
+Global key press callback for the window.
+*/
 gboolean key_press(GtkWidget *widget, GdkEvent *event, gpointer user_data)
 {
 	if(event->key.keyval==GDK_KEY_Escape)
@@ -651,13 +789,27 @@ gboolean key_press(GtkWidget *widget, GdkEvent *event, gpointer user_data)
 	return FALSE;
 }
 
+void show_help(void)
+{
+	printf("pmount-gui\n"
+		"Copyright (c) 2011-2015 Mikko Rasa, Mikkosoft Productions\n\n"
+		"Usage: pmount-gui [-v] [-u] [-r <command>] [-h]\n\n"
+		"Options:\n"
+		"  -v  Increase verbosity\n"
+		"  -u  Unmount a device (default is mount)\n"
+		"  -r  Run a command after mounting\n"
+		"  -h  Display this help\n");
+}
+
 int main(int argc, char **argv)
 {
 	GtkWidget *window;
+	GtkWidget *box;
 	GtkWidget *viewport;
 	GtkWidget *list;
 	GtkListStore *store;
 	GtkTreeSelection *selection;
+	GtkWidget *button;
 	GtkTreeIter iter;
 	Device *devices;
 	int i;
@@ -668,7 +820,7 @@ int main(int argc, char **argv)
 
 	gtk_init(&argc, &argv);
 
-	while((opt = getopt(argc, argv, "vu"))!=-1) switch(opt)
+	while((opt = getopt(argc, argv, "vur:h"))!=-1) switch(opt)
 	{
 	case 'v':
 		++verbosity;
@@ -676,6 +828,12 @@ int main(int argc, char **argv)
 	case 'u':
 		umount = 1;
 		break;
+	case 'r':
+		post_mount_command = optarg;
+		break;
+	case 'h':
+		show_help();
+		return 0;
 	}
 
 	window = gtk_window_new(GTK_WINDOW_TOPLEVEL);
@@ -683,9 +841,12 @@ int main(int argc, char **argv)
 	g_signal_connect(window, "destroy", G_CALLBACK(&gtk_main_quit), NULL);
 	g_signal_connect(window, "key-press-event", G_CALLBACK(&key_press), NULL);
 
+	box = gtk_vbox_new(FALSE, 5);
+	gtk_container_add(GTK_CONTAINER(window), box);
+
 	viewport = gtk_viewport_new(NULL, NULL);
 	gtk_viewport_set_shadow_type(GTK_VIEWPORT(viewport), GTK_SHADOW_IN);
-	gtk_container_add(GTK_CONTAINER(window), viewport);
+	gtk_box_pack_start(GTK_BOX(box), viewport, TRUE, TRUE, 0);
 
 	list = gtk_tree_view_new();
 	gtk_container_add(GTK_CONTAINER(viewport), list);
@@ -698,10 +859,15 @@ int main(int argc, char **argv)
 
 	selection = gtk_tree_view_get_selection(GTK_TREE_VIEW(list));
 
+	button = gtk_button_new_with_label(umount ? "Unmount" : "Mount");
+	g_signal_connect(button, "clicked", G_CALLBACK(&button_clicked), list);
+	gtk_box_pack_start(GTK_BOX(box), button, FALSE, TRUE, 0);
+
 	devices = get_devices();
 	n_listed = 0;
 	if(devices)
 	{
+		/* Populate the list with devices in appropriate state. */
 		latest = 0;
 		for(i=0; devices[i].node; ++i)
 			if(!devices[i].mounted==!umount)
@@ -710,6 +876,7 @@ int main(int argc, char **argv)
 				gtk_list_store_set(store, &iter, 0, devices[i].description, 1, &devices[i], -1);
 				if(devices[i].time>latest)
 				{
+					/* Pre-select the device that appeared on the system most recently. */
 					latest = devices[i].time;
 					gtk_tree_selection_select_iter(selection, &iter);
 				}
@@ -725,6 +892,7 @@ int main(int argc, char **argv)
 	{
 		GtkWidget *dialog;
 
+		/* Don't show the main window if no devices were listed. */
 		dialog = gtk_message_dialog_new(NULL, 0, GTK_MESSAGE_WARNING, GTK_BUTTONS_OK,
 			"No devices to %s", (umount ? "unmount" : "mount"));
 		g_signal_connect(dialog, "response", G_CALLBACK(&gtk_main_quit), NULL);