[v2] ui/cocoa.m: Add Mount image file menu item

Add "Mount Image File..." and a "Eject Image File" menu items to
cocoa interface. This patch makes sharing files between the
host and the guest user-friendly.

The "Mount Image File..." menu item displays a dialog box having the
user pick an image file to use in QEMU. The image file is setup as
a USB flash drive. The user can do the equivalent of removing the
flash drive by selecting the file in the "Eject Image File" submenu.

Signed-off-by: John Arbuckle <programmingkidx@gmail.com>

---
Detects if the user actually specified the -usb option.
Removed the sendMonitorCommand() function. 
Replaced a lot of code with C interface equivalent of monitor commands
drive_add and device_add. 

 ui/cocoa.m |  228 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 files changed, 227 insertions(+), 1 deletions(-)

Only reviewing around qmp_device_add() and such, ignoring the GUI part.

Programmingkid <programmingkidx@gmail.com> writes:

> Add "Mount Image File..." and a "Eject Image File" menu items to
> cocoa interface. This patch makes sharing files between the
> host and the guest user-friendly.
>
> The "Mount Image File..." menu item displays a dialog box having the
> user pick an image file to use in QEMU. The image file is setup as
> a USB flash drive. The user can do the equivalent of removing the
> flash drive by selecting the file in the "Eject Image File" submenu.
>
> Signed-off-by: John Arbuckle <programmingkidx@gmail.com>
>
> ---
> Detects if the user actually specified the -usb option.
> Removed the sendMonitorCommand() function. 
> Replaced a lot of code with C interface equivalent of monitor commands
> drive_add and device_add. 
>
>  ui/cocoa.m |  228 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
>  1 files changed, 227 insertions(+), 1 deletions(-)
>
> diff --git a/ui/cocoa.m b/ui/cocoa.m
> index 334e6f6..df1faea 100644
> --- a/ui/cocoa.m
> +++ b/ui/cocoa.m
> @@ -31,6 +31,8 @@
>  #include "sysemu/sysemu.h"
>  #include "qmp-commands.h"
>  #include "sysemu/blockdev.h"
> +#include "include/monitor/qdev.h"
> +#include "hw/boards.h"
>  
>  #ifndef MAC_OS_X_VERSION_10_5
>  #define MAC_OS_X_VERSION_10_5 1050
> @@ -52,6 +54,8 @@
>  #endif
>  
>  #define cgrect(nsrect) (*(CGRect *)&(nsrect))
> +#define USB_DISK_ID "USB_DISK"
> +#define EJECT_IMAGE_FILE_TAG 2099
>  
>  typedef struct {
>      int width;
> @@ -829,6 +833,9 @@ QemuCocoaView *cocoaView;
>  - (void)powerDownQEMU:(id)sender;
>  - (void)ejectDeviceMedia:(id)sender;
>  - (void)changeDeviceMedia:(id)sender;
> +- (void)mountImageFile:(id)sender;
> +- (void)ejectImageFile:(id)sender;
> +- (void)updateEjectImageMenuItems;
>  @end
>  
>  @implementation QemuCocoaAppController
> @@ -1125,6 +1132,179 @@ QemuCocoaView *cocoaView;
>      }
>  }
>  
> +/* Displays a dialog box asking the user for an image file to mount */
> +- (void)mountImageFile:(id)sender
> +{
> +    /* Display the file open dialog */
> +    NSOpenPanel * openPanel;
> +    openPanel = [NSOpenPanel openPanel];
> +    [openPanel setCanChooseFiles: YES];
> +    [openPanel setAllowsMultipleSelection: NO];
> +    [openPanel setAllowedFileTypes: supportedImageFileTypes];
> +    if([openPanel runModal] == NSFileHandlingPanelOKButton) {
> +        NSString * file = [[[openPanel URLs] objectAtIndex: 0] path];
> +        if(file == nil) {
> +            NSBeep();
> +            QEMU_Alert(@"Failed to convert URL to file path!");
> +            return;
> +        }
> +
> +        static int usbDiskCount;
> +        char *idString, *fileName, *driveOptions, *fileNameHint;
> +
> +        /* Create the file name hint */
> +        NSString *stringBuffer;
> +        const int fileNameHintSize = 10;
> +        stringBuffer = [file lastPathComponent];
> +        stringBuffer = [stringBuffer stringByDeletingPathExtension];
> +        if([stringBuffer length] > fileNameHintSize) {
> +            stringBuffer = [stringBuffer substringToIndex: fileNameHintSize];
> +        }
> +        fileNameHint = g_strdup_printf("%s",
> +                    [stringBuffer cStringUsingEncoding: NSASCIIStringEncoding]);
> +
> +        idString = g_strdup_printf("%s_%s_%d", USB_DISK_ID, fileNameHint,
> +                                                                usbDiskCount++);

Indentation is off, long line.

We don't use CamelCase for variable names in QEMU.  See CODING_STYLE,
section 3. Naming.

More of the same elsewhere.

Your system-generated ID can theoretically clash with a user-specified
ID.  We should reserve a name space for system-generated IDs.  Related:
our discussion Re: Should we auto-generate IDs?  Anyway, wider issue,
not something this patch can solve.

> +
> +        fileName = g_strdup_printf("%s",
> +                            [file cStringUsingEncoding: NSASCIIStringEncoding]);
> +
> +        /* drive_add equivalent code */
> +        driveOptions = g_strdup_printf("if=none,id=%s,file=%s", idString,
> +                                                                     fileName);
> +        DriveInfo *dinfo;
> +        QemuOpts *opts;
> +        MachineClass *mc;

No declarations in the middle of blocks, please.  See CODING_STYLE
section 5. Declarations.

More of the same elsewhere.

> +
> +        opts = drive_def(driveOptions);

Breaks when fileName contains a comma.  Fine example of why formatting
stuff only to parse it apart again is a bad idea.  Use drive_add()
instead.  Roughly like

        opts = drive_add(IF_NONE, -1, file_name, "");

You could've found this yourself easily had you slowed down a bit to
examine how we create drive QemuOpts elsewhere.

> +        if (!opts) {
> +            QEMU_Alert(@"Error: could not create QemuOpts object!");
> +            return;
> +        }
> +
> +        mc = MACHINE_GET_CLASS(current_machine);
> +        dinfo = drive_new(opts, mc->block_default_type);
> +        if (!dinfo) {
> +            qemu_opts_del(opts);
> +            QEMU_Alert(@"Error: could not create DriveInfo object!");
> +            return;
> +        }

The real error messages will end up on stderr.  The proper interface to
use will be blockdev_init(), or maybe qmp_blockdev_add().  "Will be"
because they're still being developed, and using them in this state
might be too much to ask of you.

> +
> +        /* device_add equivalent code */
> +
> +        /* Create the QDict object */
> +        QDict * qdict;
> +        qdict = qdict_new();
> +        qdict_set_default_str(qdict, "driver", "usb-storage");
> +        qdict_set_default_str(qdict, "id", idString);
> +        qdict_set_default_str(qdict, "drive", idString);

Using the same ID for two different things happens to work at this time,
but it's confusing, and best avoided.

> +
> +        QObject *ret_data;
> +        ret_data = g_malloc(1); /* This is just to silence a warning */

Must be ret_data = NULL.

> +
> +        Error *errp = NULL;
> +        qmp_device_add(qdict, &ret_data, &errp);
> +        handleAnyDeviceErrors(errp);
> +        [self updateEjectImageMenuItems];
> +
> +        g_free(qdict);
> +        g_free(fileName);
> +        g_free(idString);
> +        g_free(driveOptions);
> +        g_free(ret_data);

You leak most of these on your error returns.

Didn't check whether you leak anything here.

> +    }
> +}
> +
> +/* Removes an image file from QEMU */
> +- (void)ejectImageFile:(id) sender
> +{
> +    NSString *imageFileID;
> +
> +    imageFileID = [sender representedObject];
> +    if (imageFileID == nil) {
> +        NSBeep();
> +        QEMU_Alert(@"Could not find image file's ID!");
> +        return;
> +    }
> +
> +    Error *errp = NULL;
> +    qmp_device_del([imageFileID cStringUsingEncoding: NSASCIIStringEncoding],
> +                                                                          &errp);
> +    handleAnyDeviceErrors(errp);
> +    [self updateEjectImageMenuItems];
> +}
> +
> +/* Gives each mounted image file an eject menu item */
> +- (void) updateEjectImageMenuItems
> +{
> +    NSMenu *machineMenu;
> +    machineMenu = [[[NSApp mainMenu] itemWithTitle:@"Machine"] submenu];
> +
> +    /* Remove old menu items*/
> +    NSMenu * ejectSubmenu;
> +    ejectSubmenu = [[machineMenu itemWithTag: EJECT_IMAGE_FILE_TAG] submenu];
> +    if(!ejectSubmenu) {
> +        NSBeep();
> +        QEMU_Alert(@"Failed to find eject submenu!");
> +        return;
> +    }
> +    int index;
> +    for (index = 0; index < [ejectSubmenu numberOfItems]; index++) {
> +        [ejectSubmenu removeItemAtIndex: 0];
> +    }
> +     /* Needed probably because of a bug with cocoa */
> +    if ([ejectSubmenu numberOfItems] > 0) {
> +        [ejectSubmenu removeItemAtIndex: 0];
> +    }
> +
> +    BlockInfoList *currentDevice;
> +    currentDevice = qmp_query_block(NULL);
> +
> +    NSString *fileName, *deviceName;
> +    NSMenuItem *ejectFileMenuItem;  /* Used with each mounted image file */
> +
> +    /* Look for mounted image files */
> +    while(currentDevice) {
> +        if (!currentDevice->value || !currentDevice->value->inserted
> +                                  || !currentDevice->value->inserted->file) {
> +            currentDevice = currentDevice->next;
> +            continue;
> +        }
> +
> +        /* if the device's name is the generated ID */
> +        if (!strstr(currentDevice->value->device, USB_DISK_ID)) {
> +            currentDevice = currentDevice->next;
> +            continue;
> +        }
> +
> +        fileName = [NSString stringWithFormat: @"%s", currentDevice->value->inserted->file];
> +        fileName = [fileName lastPathComponent]; /* To obtain only the file name */
> +
> +        ejectFileMenuItem = [[NSMenuItem alloc] initWithTitle: [NSString stringWithFormat: @"Eject %@", fileName]
> +                                                  action: @selector(ejectImageFile:)
> +                                           keyEquivalent: @""];
> +        [ejectSubmenu addItem: ejectFileMenuItem];
> +        deviceName = [NSString stringWithFormat: @"%s", currentDevice->value->device];
> +        [ejectFileMenuItem setRepresentedObject: deviceName];
> +        [ejectFileMenuItem autorelease];
> +        currentDevice = currentDevice->next;
> +    }
> +
> +    /* Add default menu item if submenu is empty */
> +    if([ejectSubmenu numberOfItems] == 0) {
> +
> +        /* Create the default menu item */
> +        NSMenuItem *emptyMenuItem;
> +        emptyMenuItem = [NSMenuItem new];
> +        [emptyMenuItem setTitle: @"No items available"];
> +        [emptyMenuItem setEnabled: NO];
> +
> +        /* Add the default menu item to the submenu */
> +        [ejectSubmenu addItem: emptyMenuItem];
> +        [emptyMenuItem release];
> +    }
> +}
> +
>  @end
>  
>  
> @@ -1338,10 +1518,52 @@ static void add_console_menu_entries(void)
>      }
>  }
>  
> +/* Determines if USB is available */
> +static bool usbAvailable(void)
> +{
> +    /* Look thru all the arguments sent to QEMU for '-usb' */
> +    int index;
> +    for (index = 0; index < gArgc; index++) {
> +        if(strcmp(gArgv[index], "-usb") == 0) {
> +            return true;
> +        }
> +    }
> +    return false;
> +}

-usb is just one way to enable USB.  There's also --usb, and variations
on --machine usb=on.  USB may even be enabled by default.

You need to search QOM for USB sockets.

> +
> +/* Adds menu items that can mount an image file like a usb flash drive */
> +static void addImageMountingMenus(NSMenu *menu)
> +{
> +    [menu addItem: [[[NSMenuItem alloc] initWithTitle: @"Mount Image File..."
> +           action: @selector(mountImageFile:) keyEquivalent: @""] autorelease]];
> +
> +    /* Create the eject menu item */
> +    NSMenuItem *ejectMenuItem;
> +    ejectMenuItem = [NSMenuItem new];
> +    [ejectMenuItem setTitle: @"Eject Image File"];
> +    [ejectMenuItem setTag: EJECT_IMAGE_FILE_TAG];
> +    [menu addItem: ejectMenuItem];
> +    [ejectMenuItem autorelease];

Okay, one drive-by GUI remark: We eject media, we unplug devices.
Ejecting image files makes no sense to me :)

> +
> +    /* Create the default menu item for the eject menu item's submenu*/
> +    NSMenuItem *emptyMenuItem;
> +    emptyMenuItem = [NSMenuItem new];
> +    [emptyMenuItem setTitle: @"No items available"];
> +    [emptyMenuItem setEnabled: NO];
> +    [emptyMenuItem autorelease];
> +
> +    /* Add the default menu item to the submenu, the "No items" menu item */
> +    NSMenu *submenu;
> +    submenu = [NSMenu new];
> +    [ejectMenuItem setSubmenu: submenu];
> +    [submenu addItem: emptyMenuItem];
> +    [submenu autorelease];
> +}
> +
>  /* Make menu items for all removable devices.
>   * Each device is given an 'Eject' and 'Change' menu item.
>   */
> -static void addRemovableDevicesMenuItems()
> +static void addRemovableDevicesMenuItems(void)
>  {
>      NSMenu *menu;
>      NSMenuItem *menuItem;
> @@ -1402,6 +1624,10 @@ static void addRemovableDevicesMenuItems()
>          currentDevice = currentDevice->next;
>      }
>      qapi_free_BlockInfoList(pointerToFree);
> +
> +    if(usbAvailable() == true){
> +        addImageMountingMenus(menu);
> +    }
>  }
>  
>  void cocoa_display_init(DisplayState *ds, int full_screen)

On Sep 11, 2015, at 3:40 AM, Markus Armbruster wrote:

> Only reviewing around qmp_device_add() and such, ignoring the GUI part.
> 
> Programmingkid <programmingkidx@gmail.com> writes:
> 
>> Add "Mount Image File..." and a "Eject Image File" menu items to
>> cocoa interface. This patch makes sharing files between the
>> host and the guest user-friendly.
>> 
>> The "Mount Image File..." menu item displays a dialog box having the
>> user pick an image file to use in QEMU. The image file is setup as
>> a USB flash drive. The user can do the equivalent of removing the
>> flash drive by selecting the file in the "Eject Image File" submenu.
>> 
>> Signed-off-by: John Arbuckle <programmingkidx@gmail.com>
>> 
>> ---
>> Detects if the user actually specified the -usb option.
>> Removed the sendMonitorCommand() function. 
>> Replaced a lot of code with C interface equivalent of monitor commands
>> drive_add and device_add. 
>> 
>> ui/cocoa.m |  228 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
>> 1 files changed, 227 insertions(+), 1 deletions(-)
>> 
>> diff --git a/ui/cocoa.m b/ui/cocoa.m
>> index 334e6f6..df1faea 100644
>> --- a/ui/cocoa.m
>> +++ b/ui/cocoa.m
>> @@ -31,6 +31,8 @@
>> #include "sysemu/sysemu.h"
>> #include "qmp-commands.h"
>> #include "sysemu/blockdev.h"
>> +#include "include/monitor/qdev.h"
>> +#include "hw/boards.h"
>> 
>> #ifndef MAC_OS_X_VERSION_10_5
>> #define MAC_OS_X_VERSION_10_5 1050
>> @@ -52,6 +54,8 @@
>> #endif
>> 
>> #define cgrect(nsrect) (*(CGRect *)&(nsrect))
>> +#define USB_DISK_ID "USB_DISK"
>> +#define EJECT_IMAGE_FILE_TAG 2099
>> 
>> typedef struct {
>>     int width;
>> @@ -829,6 +833,9 @@ QemuCocoaView *cocoaView;
>> - (void)powerDownQEMU:(id)sender;
>> - (void)ejectDeviceMedia:(id)sender;
>> - (void)changeDeviceMedia:(id)sender;
>> +- (void)mountImageFile:(id)sender;
>> +- (void)ejectImageFile:(id)sender;
>> +- (void)updateEjectImageMenuItems;
>> @end
>> 
>> @implementation QemuCocoaAppController
>> @@ -1125,6 +1132,179 @@ QemuCocoaView *cocoaView;
>>     }
>> }
>> 
>> +/* Displays a dialog box asking the user for an image file to mount */
>> +- (void)mountImageFile:(id)sender
>> +{
>> +    /* Display the file open dialog */
>> +    NSOpenPanel * openPanel;
>> +    openPanel = [NSOpenPanel openPanel];
>> +    [openPanel setCanChooseFiles: YES];
>> +    [openPanel setAllowsMultipleSelection: NO];
>> +    [openPanel setAllowedFileTypes: supportedImageFileTypes];
>> +    if([openPanel runModal] == NSFileHandlingPanelOKButton) {
>> +        NSString * file = [[[openPanel URLs] objectAtIndex: 0] path];
>> +        if(file == nil) {
>> +            NSBeep();
>> +            QEMU_Alert(@"Failed to convert URL to file path!");
>> +            return;
>> +        }
>> +
>> +        static int usbDiskCount;
>> +        char *idString, *fileName, *driveOptions, *fileNameHint;
>> +
>> +        /* Create the file name hint */
>> +        NSString *stringBuffer;
>> +        const int fileNameHintSize = 10;
>> +        stringBuffer = [file lastPathComponent];
>> +        stringBuffer = [stringBuffer stringByDeletingPathExtension];
>> +        if([stringBuffer length] > fileNameHintSize) {
>> +            stringBuffer = [stringBuffer substringToIndex: fileNameHintSize];
>> +        }
>> +        fileNameHint = g_strdup_printf("%s",
>> +                    [stringBuffer cStringUsingEncoding: NSASCIIStringEncoding]);
>> +
>> +        idString = g_strdup_printf("%s_%s_%d", USB_DISK_ID, fileNameHint,
>> +                                                                usbDiskCount++);
> 
> Indentation is off, long line.
I assume you are talking about the "usbDiskCount++);" part. Did you want it more
right justified?

> We don't use CamelCase for variable names in QEMU.  See CODING_STYLE,
> section 3. Naming.

Good catch. 

> 
> More of the same elsewhere.
> 
> Your system-generated ID can theoretically clash with a user-specified
> ID.  
The gui code does run at the start of QEMU. But the user could have specified
an ID at the command line. Given how long the auto-generated ID is, I think
there is little probability that would happen. I can make the auto-generated
ID impossible for the user to use by using a '#' character at the start. 

> We should reserve a name space for system-generated IDs.  Related:
> our discussion Re: Should we auto-generate IDs?  Anyway, wider issue,
> not something this patch can solve.
I don't like mixing topics in emails but what was the outcome of the fifth great
discussion on auto-generated ID's? Are you or another maintainer going to use
someone's patch?

> 
>> +
>> +        fileName = g_strdup_printf("%s",
>> +                            [file cStringUsingEncoding: NSASCIIStringEncoding]);
>> +
>> +        /* drive_add equivalent code */
>> +        driveOptions = g_strdup_printf("if=none,id=%s,file=%s", idString,
>> +                                                                     fileName);
>> +        DriveInfo *dinfo;
>> +        QemuOpts *opts;
>> +        MachineClass *mc;
> 
> No declarations in the middle of blocks, please.  See CODING_STYLE
> section 5. Declarations.

Another good catch.

> 
> More of the same elsewhere.
> 
>> +
>> +        opts = drive_def(driveOptions);
> 
> Breaks when fileName contains a comma.  
Thanks for catching it.

> Fine example of why formatting
> stuff only to parse it apart again is a bad idea.  Use drive_add()
> instead.  Roughly like
> 
>        opts = drive_add(IF_NONE, -1, file_name, "");

I tired using drive_add() so many times. It didn't work. Using 'info block' in
the monitor is how I checked. 

> You could've found this yourself easily had you slowed down a bit to
> examine how we create drive QemuOpts elsewhere.
> 
>> +        if (!opts) {
>> +            QEMU_Alert(@"Error: could not create QemuOpts object!");
>> +            return;
>> +        }
>> +
>> +        mc = MACHINE_GET_CLASS(current_machine);
>> +        dinfo = drive_new(opts, mc->block_default_type);
>> +        if (!dinfo) {
>> +            qemu_opts_del(opts);
>> +            QEMU_Alert(@"Error: could not create DriveInfo object!");
>> +            return;
>> +        }
> 
> The real error messages will end up on stderr.  The proper interface to
> use will be blockdev_init(), or maybe qmp_blockdev_add().  "Will be"
> because they're still being developed, and using them in this state
> might be too much to ask of you.

qmp_blockdev_add() has that BlockdevOptions type that doesn't
look easy to use. 

blockdev_init() looks usable. The only thing to find out
is what does it expect to be in its QDict parameter. 

There doesn't seem to be a problem with drive_new(). There is no indication
that the function is depreciated.

> 
>> +
>> +        /* device_add equivalent code */
>> +
>> +        /* Create the QDict object */
>> +        QDict * qdict;
>> +        qdict = qdict_new();
>> +        qdict_set_default_str(qdict, "driver", "usb-storage");
>> +        qdict_set_default_str(qdict, "id", idString);
>> +        qdict_set_default_str(qdict, "drive", idString);
> 
> Using the same ID for two different things happens to work at this time,
> but it's confusing, and best avoided.

Didn't know this was a problem. I just followed the example from here:
https://wiki.ubuntu.com/QemuDiskHotplug#Hotplug_USB_Disk]

What do you suggest I use for "drive"?


> 
>> +
>> +        QObject *ret_data;
>> +        ret_data = g_malloc(1); /* This is just to silence a warning */
> 
> Must be ret_data = NULL.

Excellent idea.

> 
>> +
>> +        Error *errp = NULL;
>> +        qmp_device_add(qdict, &ret_data, &errp);
>> +        handleAnyDeviceErrors(errp);
>> +        [self updateEjectImageMenuItems];
>> +
>> +        g_free(qdict);
>> +        g_free(fileName);
>> +        g_free(idString);
>> +        g_free(driveOptions);
>> +        g_free(ret_data);
> 
> You leak most of these on your error returns.
A goto statement will fix this. 

> Didn't check whether you leak anything here.
> 
>> +    }
>> +}
>> +
>> +/* Removes an image file from QEMU */
>> +- (void)ejectImageFile:(id) sender
>> +{
>> +    NSString *imageFileID;
>> +
>> +    imageFileID = [sender representedObject];
>> +    if (imageFileID == nil) {
>> +        NSBeep();
>> +        QEMU_Alert(@"Could not find image file's ID!");
>> +        return;
>> +    }
>> +
>> +    Error *errp = NULL;
>> +    qmp_device_del([imageFileID cStringUsingEncoding: NSASCIIStringEncoding],
>> +                                                                          &errp);
>> +    handleAnyDeviceErrors(errp);
>> +    [self updateEjectImageMenuItems];
>> +}
>> +
>> +/* Gives each mounted image file an eject menu item */
>> +- (void) updateEjectImageMenuItems
>> +{
>> +    NSMenu *machineMenu;
>> +    machineMenu = [[[NSApp mainMenu] itemWithTitle:@"Machine"] submenu];
>> +
>> +    /* Remove old menu items*/
>> +    NSMenu * ejectSubmenu;
>> +    ejectSubmenu = [[machineMenu itemWithTag: EJECT_IMAGE_FILE_TAG] submenu];
>> +    if(!ejectSubmenu) {
>> +        NSBeep();
>> +        QEMU_Alert(@"Failed to find eject submenu!");
>> +        return;
>> +    }
>> +    int index;
>> +    for (index = 0; index < [ejectSubmenu numberOfItems]; index++) {
>> +        [ejectSubmenu removeItemAtIndex: 0];
>> +    }
>> +     /* Needed probably because of a bug with cocoa */
>> +    if ([ejectSubmenu numberOfItems] > 0) {
>> +        [ejectSubmenu removeItemAtIndex: 0];
>> +    }
>> +
>> +    BlockInfoList *currentDevice;
>> +    currentDevice = qmp_query_block(NULL);
>> +
>> +    NSString *fileName, *deviceName;
>> +    NSMenuItem *ejectFileMenuItem;  /* Used with each mounted image file */
>> +
>> +    /* Look for mounted image files */
>> +    while(currentDevice) {
>> +        if (!currentDevice->value || !currentDevice->value->inserted
>> +                                  || !currentDevice->value->inserted->file) {
>> +            currentDevice = currentDevice->next;
>> +            continue;
>> +        }
>> +
>> +        /* if the device's name is the generated ID */
>> +        if (!strstr(currentDevice->value->device, USB_DISK_ID)) {
>> +            currentDevice = currentDevice->next;
>> +            continue;
>> +        }
>> +
>> +        fileName = [NSString stringWithFormat: @"%s", currentDevice->value->inserted->file];
>> +        fileName = [fileName lastPathComponent]; /* To obtain only the file name */
>> +
>> +        ejectFileMenuItem = [[NSMenuItem alloc] initWithTitle: [NSString stringWithFormat: @"Eject %@", fileName]
>> +                                                  action: @selector(ejectImageFile:)
>> +                                           keyEquivalent: @""];
>> +        [ejectSubmenu addItem: ejectFileMenuItem];
>> +        deviceName = [NSString stringWithFormat: @"%s", currentDevice->value->device];
>> +        [ejectFileMenuItem setRepresentedObject: deviceName];
>> +        [ejectFileMenuItem autorelease];
>> +        currentDevice = currentDevice->next;
>> +    }
>> +
>> +    /* Add default menu item if submenu is empty */
>> +    if([ejectSubmenu numberOfItems] == 0) {
>> +
>> +        /* Create the default menu item */
>> +        NSMenuItem *emptyMenuItem;
>> +        emptyMenuItem = [NSMenuItem new];
>> +        [emptyMenuItem setTitle: @"No items available"];
>> +        [emptyMenuItem setEnabled: NO];
>> +
>> +        /* Add the default menu item to the submenu */
>> +        [ejectSubmenu addItem: emptyMenuItem];
>> +        [emptyMenuItem release];
>> +    }
>> +}
>> +
>> @end
>> 
>> 
>> @@ -1338,10 +1518,52 @@ static void add_console_menu_entries(void)
>>     }
>> }
>> 
>> +/* Determines if USB is available */
>> +static bool usbAvailable(void)
>> +{
>> +    /* Look thru all the arguments sent to QEMU for '-usb' */
>> +    int index;
>> +    for (index = 0; index < gArgc; index++) {
>> +        if(strcmp(gArgv[index], "-usb") == 0) {
>> +            return true;
>> +        }
>> +    }
>> +    return false;
>> +}
> 
> -usb is just one way to enable USB.  There's also --usb, and variations
> on --machine usb=on.  USB may even be enabled by default.
> 
> You need to search QOM for USB sockets.

Do you know of example code I could study that does this?

> 
>> +
>> +/* Adds menu items that can mount an image file like a usb flash drive */
>> +static void addImageMountingMenus(NSMenu *menu)
>> +{
>> +    [menu addItem: [[[NSMenuItem alloc] initWithTitle: @"Mount Image File..."
>> +           action: @selector(mountImageFile:) keyEquivalent: @""] autorelease]];
>> +
>> +    /* Create the eject menu item */
>> +    NSMenuItem *ejectMenuItem;
>> +    ejectMenuItem = [NSMenuItem new];
>> +    [ejectMenuItem setTitle: @"Eject Image File"];
>> +    [ejectMenuItem setTag: EJECT_IMAGE_FILE_TAG];
>> +    [menu addItem: ejectMenuItem];
>> +    [ejectMenuItem autorelease];
> 
> Okay, one drive-by GUI remark: We eject media, we unplug devices.
> Ejecting image files makes no sense to me :)

I think eject conveys the message of removing something from the system. 
Just thinking about a menu item called "unplug" makes me cringe.

> 
>> +
>> +    /* Create the default menu item for the eject menu item's submenu*/
>> +    NSMenuItem *emptyMenuItem;
>> +    emptyMenuItem = [NSMenuItem new];
>> +    [emptyMenuItem setTitle: @"No items available"];
>> +    [emptyMenuItem setEnabled: NO];
>> +    [emptyMenuItem autorelease];
>> +
>> +    /* Add the default menu item to the submenu, the "No items" menu item */
>> +    NSMenu *submenu;
>> +    submenu = [NSMenu new];
>> +    [ejectMenuItem setSubmenu: submenu];
>> +    [submenu addItem: emptyMenuItem];
>> +    [submenu autorelease];
>> +}
>> +
>> /* Make menu items for all removable devices.
>>  * Each device is given an 'Eject' and 'Change' menu item.
>>  */
>> -static void addRemovableDevicesMenuItems()
>> +static void addRemovableDevicesMenuItems(void)
>> {
>>     NSMenu *menu;
>>     NSMenuItem *menuItem;
>> @@ -1402,6 +1624,10 @@ static void addRemovableDevicesMenuItems()
>>         currentDevice = currentDevice->next;
>>     }
>>     qapi_free_BlockInfoList(pointerToFree);
>> +
>> +    if(usbAvailable() == true){
>> +        addImageMountingMenus(menu);
>> +    }
>> }
>> 
>> void cocoa_display_init(DisplayState *ds, int full_screen)


Thank you very much for helping.