]> git.tdb.fi Git - pmount-gui.git/blobdiff - main.c
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[pmount-gui.git] / main.c
diff --git a/main.c b/main.c
index bed5e1bf0dd0964c69e6fa161816e6d05a9ec075..ae08cbb7cda87de794b03d673e40a6de691e721e 100644 (file)
--- 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;
@@ -527,113 +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))
+       if(!gtk_tree_model_get_iter(model, &iter, path))
+               return;
+
+       gtk_tree_model_get(model, &iter, 1, &device, -1);
+
+       pipe(pipe_fd);
+
+       pid = fork();
+       if(pid==0)
        {
-               Device *device;
-               int pid;
-               int pipe_fd[2];
+               /* Child process */
+               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);
+               else
+                       execl("/usr/bin/pmount", "pmount", device->node, device->label, NULL);
+               _exit(1);
+       }
+       else if(pid<0)
+               return;
 
-               gtk_tree_model_get(model, &iter, 1, &device, -1);
+       /* Parent process */
 
-               pipe(pipe_fd);
+       close(pipe_fd[1]);
+       FD_ZERO(&fds);
+       FD_SET(pipe_fd[0], &fds);
+       timeout.tv_sec = 0;
+       timeout.tv_usec = 200000;
 
-               pid = fork();
-               if(pid==0)
+       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))
                {
-                       if(verbosity>=1)
-                       {
-                               if(umount)
-                                       printf("Running pumount %s\n", device->node);
-                               else
-                                       printf("Running pmount %s %s\n", device->node, device->label);
-                       }
+                       int len;
 
-                       close(pipe_fd[0]);
-                       dup2(pipe_fd[1], 1);
-                       dup2(pipe_fd[1], 2);
+                       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;
+               }
+       }
 
-                       if(umount)
-                               execl("/usr/bin/pumount", "pumount", device->node, NULL);
+       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
-                               execl("/usr/bin/pmount", "pmount", device->node, device->label, NULL);
-                       _exit(1);
+                               printf("Command exited with status %d\n", WEXITSTATUS(status));
                }
-               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;
+               else if(WIFSIGNALED(status))
+                       printf("Command terminated with signal %d\n", WTERMSIG(status));
+               else
+                       printf("Command exited with unknown result %04X\n", status);
+       }
 
-                                       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;
-                               }
-                       }
+       if(!WIFEXITED(status) || WEXITSTATUS(status))
+       {
+               GtkWidget *dialog;
 
-                       if(pid)
-                               waitpid(pid, &status, 0);
+               /* 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;
+       }
 
-                       buf[pos] = 0;
+       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)
-                       {
-                               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);
-                       }
+                               printf("Running %s in %s\n", post_mount_command, workdir);
 
-                       if(!WIFEXITED(status) || WEXITSTATUS(status))
+                       pid = fork();
+                       if(pid==0)
                        {
-                               GtkWidget *dialog;
-
-                               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);
+                               chdir(workdir);
+                               execlp(post_mount_command, post_mount_command, NULL);
+                               _exit(1);
                        }
-                       else
-                               gtk_main_quit();
                }
        }
 
        (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)
@@ -648,13 +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;
@@ -665,7 +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;
@@ -673,6 +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);
@@ -680,9 +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);
@@ -695,10 +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)
@@ -707,6 +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);
                                }
@@ -722,6 +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);