Wie erhalte ich Benachrichtigungen für SD-Karten-Ereignisse?

Ich möchte das Vorhandensein einer SD-Karte überprüfen und Benachrichtigungen für SD-Karte hinzufügen/entfernen erhalten.Wie erhalte ich Benachrichtigungen für SD-Karten-Ereignisse?

Bisher habe ich libudev verwendet, und ich habe eine kleine Anwendung gemacht, die für SD-Kartenereignisse abhört.

Der Code ist unten aufgeführt:

#include <unistd.h> 
#include <stdio.h> 
#include <stdlib.h> 
#include <string.h> 
#include <stddef.h> 
#include <errno.h> 
#include <sys/time.h> //debug -> remove me 

#include <libudev.h> 

#define ADD_FILTER "add" 
#define REMOVE_FILTER "remove" 
#define SUBSYSTEM_FILTER "block" 
#define ATTR_FILTER "ID_MODEL" 
#define SD_ATTR_VALUE "SD_MMC" 
#define ATTR_ACTIVE_SD "ID_PART_TABLE_TYPE" 

static bool isDeviceSD(struct udev_device *device); 
static bool isDevPresent(struct udev *device); 
static void print_device(struct udev_device *device, const char *source); //for debugging -> remove me 
static bool s_bSD_present; 

int main() 
{ 
    struct udev *udev; 
    struct udev_monitor *udev_monitor = NULL; 
    fd_set readfds; 
    s_bSD_present = false; 

    udev = udev_new(); 
    if (udev == NULL) 
    { 
     printf("udev_new FAILED \n"); 
     return 1; 
    } 

    s_bSD_present = isDevPresent(udev); 
    if(s_bSD_present) 
    { 
     printf("+++SD is plugged in \n"); 
    } 
    else 
    { 
     printf("---SD is not plugged in \n"); 
    } 

    udev_monitor = udev_monitor_new_from_netlink(udev, "udev"); 
    if (udev_monitor == NULL) { 
     printf("udev_monitor_new_from_netlink FAILED \n"); 
     return 1; 
    } 

    //add some filters 
    if(udev_monitor_filter_add_match_subsystem_devtype(udev_monitor, SUBSYSTEM_FILTER, NULL) < 0) 
    { 
     printf("udev_monitor_filter_add_match_subsystem_devtype FAILED \n"); 
     return 1; 
    } 

    if (udev_monitor_enable_receiving(udev_monitor) < 0) 
    { 
     printf("udev_monitor_enable_receiving FAILED \n"); 
     return 1; 
    } 

    while (1) { 
     printf("Polling for new data... \n"); 

     int fdcount = 0; 

     FD_ZERO(&readfds); 

     if (udev_monitor != NULL) 
     { 
      FD_SET(udev_monitor_get_fd(udev_monitor), &readfds); 
     } 

     fdcount = select(udev_monitor_get_fd(udev_monitor)+1, &readfds, NULL, NULL, NULL); 
     if (fdcount < 0) 
     { 
      if (errno != EINTR) 
       printf("Error receiving uevent message\n"); 
      continue; 
     } 

     if ((udev_monitor != NULL) && FD_ISSET(udev_monitor_get_fd(udev_monitor), &readfds)) 
     { 
      struct udev_device *device; 

      device = udev_monitor_receive_device(udev_monitor); 
      if (device == NULL) 
       continue; 

      //check the action 
      const char* szAction = udev_device_get_action(device); 
      if(strcmp(szAction, ADD_FILTER) == 0) 
      { 
       if(!s_bSD_present && isDeviceSD(device)) 
       { 
        s_bSD_present = true; 
        printf("+++SD has been plugged in \n"); 
       } 
      } 
      else if(strcmp(szAction, REMOVE_FILTER) == 0) 
      { 
       if(s_bSD_present && isDeviceSD(device)) 
       { 
        s_bSD_present = false; 
        printf("---SD has been removed \n"); 
       } 
      } 

      udev_device_unref(device); 
     } 
    } 

    return 0; 
} 

static bool isDeviceSD(struct udev_device *device) 
{ 
    bool retVal = false; 
    struct udev_list_entry *list_entry = 0; 
    struct udev_list_entry* model_entry = 0; 
    struct udev_list_entry* active_sd_entry = 0; 

    list_entry = udev_device_get_properties_list_entry(device); 
    model_entry = udev_list_entry_get_by_name(list_entry, ATTR_FILTER); 
    if(0 != model_entry) 
    { 
     const char* szModelValue = udev_list_entry_get_value(model_entry); 
     active_sd_entry = udev_list_entry_get_by_name(list_entry, ATTR_ACTIVE_SD); 
     if(strcmp(szModelValue, SD_ATTR_VALUE) == 0 && active_sd_entry != 0) 
     { 
      printf("Device is SD \n"); 
      retVal = true; 

      //print_device(device, "UDEV"); 
     } 
    } 
    return retVal; 
} 


static bool isDevPresent(struct udev *device) 
{ 
    bool retVal = false; 
    struct udev_enumerate *enumerate; 
    struct udev_list_entry *devices, *dev_list_entry; 

    enumerate = udev_enumerate_new(device); 
    udev_enumerate_add_match_subsystem(enumerate, SUBSYSTEM_FILTER); 
    udev_enumerate_scan_devices(enumerate); 
    devices = udev_enumerate_get_list_entry(enumerate); 

    udev_list_entry_foreach(dev_list_entry, devices) 
    { 
     struct udev_device *dev; 
     const char* dev_path = udev_list_entry_get_name(dev_list_entry); 
     dev = udev_device_new_from_syspath(device, dev_path); 

     if(true == isDeviceSD(dev)) 
     { 
      retVal = true; 
      udev_device_unref(dev); 
      break; 
     } 

     udev_device_unref(dev); 
    } 
    udev_enumerate_unref(enumerate); 

    return retVal; 
} 


static void print_device(struct udev_device *device, const char *source) 
{ 
     struct timeval tv; 
     struct timezone tz; 

     gettimeofday(&tv, &tz); 
     printf("%-6s[%llu.%06u] %-8s %s (%s)\n", 
      source, 
      (unsigned long long) tv.tv_sec, (unsigned int) tv.tv_usec, 
      udev_device_get_action(device), 
      udev_device_get_devpath(device), 
      udev_device_get_subsystem(device)); 

      struct udev_list_entry *list_entry; 

      udev_list_entry_foreach(list_entry, udev_device_get_properties_list_entry(device)) 
        printf("%s=%s\n", 
         udev_list_entry_get_name(list_entry), 
         udev_list_entry_get_value(list_entry)); 
      printf("\n"); 

}

Dieser Code erhalten Benachrichtigungen für SD-Karte hinzufügen/entfernen (und der Ausgangszustand der SD - plugged/unplugged). Es ist jedoch eher ein Hack, und es funktioniert nicht in allen Fällen.

Ich verwende derzeit das ID_MODEL Attribut des Geräts und prüfen, ob es SD_MMC ist - für SD-Karten. Ich brauche nur diese Art von Karte für jetzt, also ist es genug.

Wenn eine SD-Karte eingesetzt wird, werden folgende Ereignisse für den Subsystemblock gesendet: 2 change Ereignisse und 1 add Ereignis für jede Partition. Die Ereigniseigenschaften sind unten aufgeführt:

<----- change event - subsystem block - disk type disk -----> 

UDEV [1339412734.522055] change /devices/pci0000:00/0000:00:11.0/0000:02:03.0/usb1/1-1/1-1:1.0/host11/target11:0:0/11:0:0:2/block/sdd (block) 
UDEV_LOG=3 
ACTION=change 
DEVPATH=/devices/pci0000:00/0000:00:11.0/0000:02:03.0/usb1/1-1/1-1:1.0/host11/target11:0:0/11:0:0:2/block/sdd 
SUBSYSTEM=block 
DEVNAME=/dev/sdd 
DEVTYPE=disk 
SEQNUM=3168 
ID_VENDOR=Generic- 
ID_VENDOR_ENC=Generic- 
ID_VENDOR_ID=0bda 
ID_MODEL=SD_MMC 
ID_MODEL_ENC=SD\x2fMMC\x20\x20\x20\x20\x20\x20\x20\x20\x20\x20 
ID_MODEL_ID=0151 
ID_REVISION=1.00 
ID_SERIAL=Generic-_SD_MMC_20060413092100000-0:2 
ID_SERIAL_SHORT=20060413092100000 
ID_TYPE=disk 
ID_INSTANCE=0:2 
ID_BUS=usb 
ID_USB_INTERFACES=:080650: 
ID_USB_INTERFACE_NUM=00 
ID_USB_DRIVER=usb-storage 
ID_PATH=pci-0000:02:03.0-usb-0:1:1.0-scsi-0:0:0:2 
ID_PART_TABLE_TYPE=dos 
UDISKS_PRESENTATION_NOPOLICY=0 
UDISKS_PARTITION_TABLE=1 
UDISKS_PARTITION_TABLE_SCHEME=mbr 
UDISKS_PARTITION_TABLE_COUNT=2 
MAJOR=8 
MINOR=48 
DEVLINKS=/dev/block/8:48 /dev/disk/by-id/usb-Generic-_SD_MMC_20060413092100000-0:2 /dev/disk/by-path/pci-0000:02:03.0-usb-0:1:1.0-scsi-0:0:0:2 

<----- add event partition 1 - subsystem block - disk type partition -----> 

UDEV [1339412734.719107] add  /devices/pci0000:00/0000:00:11.0/0000:02:03.0/usb1/1-1/1-1:1.0/host11/target11:0:0/11:0:0:2/block/sdd/sdd1 (block) 
UDEV_LOG=3 
ACTION=add 
DEVPATH=/devices/pci0000:00/0000:00:11.0/0000:02:03.0/usb1/1-1/1-1:1.0/host11/target11:0:0/11:0:0:2/block/sdd/sdd1 
SUBSYSTEM=block 
DEVNAME=/dev/sdd1 
DEVTYPE=partition 
SEQNUM=3169 
ID_VENDOR=Generic- 
ID_VENDOR_ENC=Generic- 
ID_VENDOR_ID=0bda 
ID_MODEL=SD_MMC 
ID_MODEL_ENC=SD\x2fMMC\x20\x20\x20\x20\x20\x20\x20\x20\x20\x20 
ID_MODEL_ID=0151 
ID_REVISION=1.00 
ID_SERIAL=Generic-_SD_MMC_20060413092100000-0:2 
ID_SERIAL_SHORT=20060413092100000 
ID_TYPE=disk 
ID_INSTANCE=0:2 
ID_BUS=usb 
ID_USB_INTERFACES=:080650: 
ID_USB_INTERFACE_NUM=00 
ID_USB_DRIVER=usb-storage 
ID_PATH=pci-0000:02:03.0-usb-0:1:1.0-scsi-0:0:0:2 
ID_PART_TABLE_TYPE=dos 
ID_FS_UUID=6343c7b9-92a9-4d8f-bdd8-893f1190f294 
ID_FS_UUID_ENC=6343c7b9-92a9-4d8f-bdd8-893f1190f294 
ID_FS_VERSION=1.0 
ID_FS_TYPE=ext2 
ID_FS_USAGE=filesystem 
UDISKS_PRESENTATION_NOPOLICY=0 
UDISKS_PARTITION=1 
UDISKS_PARTITION_SCHEME=mbr 
UDISKS_PARTITION_NUMBER=1 
UDISKS_PARTITION_TYPE=0x83 
UDISKS_PARTITION_SIZE=1006919680 
UDISKS_PARTITION_SLAVE=/sys/devices/pci0000:00/0000:00:11.0/0000:02:03.0/usb1/1-1/1-1:1.0/host11/target11:0:0/11:0:0:2/block/sdd 
UDISKS_PARTITION_OFFSET=11618304 
UDISKS_PARTITION_ALIGNMENT_OFFSET=0 
MAJOR=8 
MINOR=49 
DEVLINKS=/dev/block/8:49 /dev/disk/by-id/usb-Generic-_SD_MMC_20060413092100000-0:2-part1 /dev/disk/by-path/pci-0000:02:03.0-usb-0:1:1.0-scsi-0:0:0:2-part1 /dev/disk/by-uuid/6343c7b9-92a9-4d8f-bdd8-893f1190f294 

<----- add event partition 2 - subsystem block - disk type partition -----> 

UDEV [1339412734.731338] add  /devices/pci0000:00/0000:00:11.0/0000:02:03.0/usb1/1-1/1-1:1.0/host11/target11:0:0/11:0:0:2/block/sdd/sdd2 (block) 
UDEV_LOG=3 
ACTION=add 
DEVPATH=/devices/pci0000:00/0000:00:11.0/0000:02:03.0/usb1/1-1/1-1:1.0/host11/target11:0:0/11:0:0:2/block/sdd/sdd2 
SUBSYSTEM=block 
DEVNAME=/dev/sdd2 
DEVTYPE=partition 
SEQNUM=3170 
ID_VENDOR=Generic- 
ID_VENDOR_ENC=Generic- 
ID_VENDOR_ID=0bda 
ID_MODEL=SD_MMC 
ID_MODEL_ENC=SD\x2fMMC\x20\x20\x20\x20\x20\x20\x20\x20\x20\x20 
ID_MODEL_ID=0151 
ID_REVISION=1.00 
ID_SERIAL=Generic-_SD_MMC_20060413092100000-0:2 
ID_SERIAL_SHORT=20060413092100000 
ID_TYPE=disk 
ID_INSTANCE=0:2 
ID_BUS=usb 
ID_USB_INTERFACES=:080650: 
ID_USB_INTERFACE_NUM=00 
ID_USB_DRIVER=usb-storage 
ID_PATH=pci-0000:02:03.0-usb-0:1:1.0-scsi-0:0:0:2 
ID_PART_TABLE_TYPE=dos 
UDISKS_PRESENTATION_NOPOLICY=0 
UDISKS_PARTITION=1 
UDISKS_PARTITION_SCHEME=mbr 
UDISKS_PARTITION_NUMBER=2 
UDISKS_PARTITION_TYPE=0xda 
UDISKS_PARTITION_SIZE=11618304 
UDISKS_PARTITION_FLAGS=boot 
UDISKS_PARTITION_SLAVE=/sys/devices/pci0000:00/0000:00:11.0/0000:02:03.0/usb1/1-1/1-1:1.0/host11/target11:0:0/11:0:0:2/block/sdd 
UDISKS_PARTITION_OFFSET=1022410752 
UDISKS_PARTITION_ALIGNMENT_OFFSET=0 
MAJOR=8 
MINOR=50 
DEVLINKS=/dev/block/8:50 /dev/disk/by-id/usb-Generic-_SD_MMC_20060413092100000-0:2-part2 /dev/disk/by-path/pci-0000:02:03.0-usb-0:1:1.0-scsi-0:0:0:2-part2

Vom change Ereignisse kann ich keine Informationen extrahieren darüber, ob das Gerät hinzugefügt oder entfernt wurde. Ich habe versucht, \dev\sdd die Gerätenamen zu öffnen, aber ich habe keine Berechtigungen, so dass Option fällt ...

Denn jetzt bin ich nur für die Partitionen, das action-Attributs Prüfung (add/remove).

Diese Version des Programms funktioniert ziemlich gut für SD-Karten, die Partitionen haben. Wenn keine Partitionen vorhanden sind, werden nur die Ereignisse change empfangen.

Also meine Frage ist: Gibt es eine Möglichkeit, ich kann überprüfen, ob das Medium wurde hinzugefügt/entfernt von der change Ereignis? Oder gibt es eine andere Möglichkeit zu überprüfen, ob ein Gerät verfügbar ist (unter Berücksichtigung des Partitionsproblems)?

Jeder Vorschlag zur Verbesserung der Geräteattribut-Iteration oder der Methode, die Benachrichtigungen zu erhalten, wäre zu begrüßen.

P.S. Und ich kann libusb :) nicht verwenden.

Quelle

2012-06-11 Alexandru C.

können Sie nicht überprüfen, ob das Blockgerät existiert, nachdem Sie ein Ereignis erhalten haben? – Behrooz

Nun, ich habe versucht, [open] (http://linux.die.net/man/2/open) auf dem 'DEVNAME'-Wert (' \ dev \ sdd') aufzurufen, aber ich habe keine Berechtigungen, also Der Anruf schlägt immer fehl. Gibt es andere Möglichkeiten zu überprüfen, ob das Gerät existiert? –

http://www.linuxquestions.org/questions/programming-9/checking-if-a-file-exists-in-c-21700/ – Behrooz

Ok. Also habe ich am PC für SD-Karten ohne Partitionen gearbeitet. dies ist

Der aktualisierte Code:

#include <unistd.h> 
#include <stdio.h> 
#include <stdlib.h> 
#include <string.h> 
#include <stddef.h> 
#include <errno.h> 
#include <sys/time.h> //debug -> remove me 
#include <sys/types.h> 
#include <sys/stat.h> 
#include <fcntl.h> 

#include <libudev.h> 

#define ADD_FILTER "add" 
#define REMOVE_FILTER "remove" 
#define SUBSYSTEM_FILTER "block" 
#define DEVTYPE_FILTER "disk" 
#define ATTR_FILTER "ID_MODEL" 
#define SD_ATTR_VALUE "SD_MMC" 
#define ATTR_ADDED_DISK "UDISKS_PARTITION_TABLE" // attribute is available for "change" event when SD card is added (n/a when removed) 

static bool isDeviceSD(struct udev_device *device); //checks if device is SD card (MMC) 
static bool isDevPresent(struct udev *device); //checks if device is present (SD + added) 
static bool isDeviceAdded(struct udev_device *device); //checks if device is added (presence of attribute ATTR_ADDED_DISK) 
static void print_device(struct udev_device *device, const char *source); //for debugging -> remove me 
static bool s_bSD_present; 

int main() 
{ 
    struct udev *udev; 
    struct udev_monitor *udev_monitor = NULL; 
    fd_set readfds; 
    s_bSD_present = false; 

    udev = udev_new(); 
    if (udev == NULL) 
    { 
     printf("udev_new FAILED \n"); 
     return 1; 
    } 

    if(isDevPresent(udev)) 
    { 
     s_bSD_present = true; 
     printf("+++SD is plugged in \n"); 
    } 
    else 
    { 
     printf("---SD is not plugged in \n"); 
    } 

    udev_monitor = udev_monitor_new_from_netlink(udev, "udev"); 
    if (udev_monitor == NULL) { 
     printf("udev_monitor_new_from_netlink FAILED \n"); 
     return 1; 
    } 

    //add some filters 
    if(udev_monitor_filter_add_match_subsystem_devtype(udev_monitor, SUBSYSTEM_FILTER, DEVTYPE_FILTER) < 0) 
    { 
     printf("udev_monitor_filter_add_match_subsystem_devtype FAILED \n"); 
     return 1; 
    } 

    if (udev_monitor_enable_receiving(udev_monitor) < 0) 
    { 
     printf("udev_monitor_enable_receiving FAILED \n"); 
     return 1; 
    } 

    while (1) { 
     printf("Polling for new data... \n"); 

     int fdcount = 0; 

     FD_ZERO(&readfds); 

     if (udev_monitor != NULL) 
     { 
      FD_SET(udev_monitor_get_fd(udev_monitor), &readfds); 
     } 

     fdcount = select(udev_monitor_get_fd(udev_monitor)+1, &readfds, NULL, NULL, NULL); 
     if (fdcount < 0) 
     { 
      if (errno != EINTR) 
       printf("Error receiving uevent message\n"); 
      continue; 
     } 

     if ((udev_monitor != NULL) && FD_ISSET(udev_monitor_get_fd(udev_monitor), &readfds)) 
     { 
      struct udev_device *device; 

      device = udev_monitor_receive_device(udev_monitor); 
      if (device == NULL) 
       continue; 

      //check presence 
      if(isDeviceSD(device) && isDeviceAdded(device)) 
      { 
       if(!s_bSD_present) //guard for double "change" events 
       { 
        s_bSD_present = true; 
        printf("+++SD has been plugged in \n"); 
       } 
      } 
      else 
      { 
       if(s_bSD_present) //not needed -> just keeping consistency 
       { 
        s_bSD_present = false; 
        printf("---SD has been removed \n"); 
       } 
      } 

      udev_device_unref(device); 
     } 
    } 

    return 0; 
} 

static bool isDeviceSD(struct udev_device *device) 
{ 
    bool retVal = false; 
    struct udev_list_entry *list_entry = 0; 
    struct udev_list_entry* model_entry = 0; 

    list_entry = udev_device_get_properties_list_entry(device); 
    model_entry = udev_list_entry_get_by_name(list_entry, ATTR_FILTER); 
    if(0 != model_entry) 
    { 
     const char* szModelValue = udev_list_entry_get_value(model_entry); 
     if(strcmp(szModelValue, SD_ATTR_VALUE) == 0) 
     { 
      //printf("Device is SD \n"); 
      retVal = true; 

      //print_device(device, "UDEV"); 
     } 
    } 
    return retVal; 
} 

static bool isDeviceAdded(struct udev_device *device) 
{ 
    bool retVal = false; 
    struct udev_list_entry *list_entry = 0; 
    struct udev_list_entry* added_disk_entry = 0; 


    list_entry = udev_device_get_properties_list_entry(device); 
    added_disk_entry = udev_list_entry_get_by_name(list_entry,/* "DEVNAME" */ ATTR_ADDED_DISK); 
    if(0 != added_disk_entry) 
    { 
     retVal = true; 
    } 
    return retVal; 
} 


static bool isDevPresent(struct udev *device) 
{ 
    bool retVal = false; 
    struct udev_enumerate *enumerate; 
    struct udev_list_entry *devices, *dev_list_entry; 

    enumerate = udev_enumerate_new(device); 
    udev_enumerate_add_match_subsystem(enumerate, SUBSYSTEM_FILTER); 
    udev_enumerate_scan_devices(enumerate); 
    devices = udev_enumerate_get_list_entry(enumerate); 

    udev_list_entry_foreach(dev_list_entry, devices) 
    { 
     struct udev_device *dev; 
     const char* dev_path = udev_list_entry_get_name(dev_list_entry); 
     dev = udev_device_new_from_syspath(device, dev_path); 

     if(isDeviceSD(dev) && isDeviceAdded(dev)) 
     { 
      retVal = true; 
      udev_device_unref(dev); 
      break; 
     } 

     udev_device_unref(dev); 
    } 
    udev_enumerate_unref(enumerate); 

    return retVal; 
} 


static void print_device(struct udev_device *device, const char *source) 
{ 
     struct timeval tv; 
     struct timezone tz; 

     gettimeofday(&tv, &tz); 
     printf("%-6s[%llu.%06u] %-8s %s (%s)\n", 
      source, 
      (unsigned long long) tv.tv_sec, (unsigned int) tv.tv_usec, 
      udev_device_get_action(device), 
      udev_device_get_devpath(device), 
      udev_device_get_subsystem(device)); 

      struct udev_list_entry *list_entry; 

      udev_list_entry_foreach(list_entry, udev_device_get_properties_list_entry(device)) 
        printf("%s=%s\n", 
         udev_list_entry_get_name(list_entry), 
         udev_list_entry_get_value(list_entry)); 
      printf("\n"); 

}

Die Lösung (noch nicht sehr hell) ist für einige Attributprüfung, die nur zur Verfügung, wenn SD-Karte hinzugefügt wird (wie UDISKS_PARTITION_TABLE).

Dies funktioniert gut auf x86.

Quelle

2012-06-12 12:45:56

Wie erhalte ich Benachrichtigungen für SD-Karten-Ereignisse?

Antwort

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