//.Y   /    100 117   /      /   /   /  70   /      /   /   /   /   /
//.YT 3 2 0 0 3 3 1     / / /
//.H!a!0:forth#092/io#092/disk_#092/raid#092/linux#092/cpp#092/Test.CPP!0.!c
// 28sep2013 Thomas Brücker

// 07dec2016: works principally!

// Raid Test
// +++++++++

#include <asm/types.h>                             // __u64
#include <errno.h>                                 // errno
#include <fcntl.h>                                 // open
#include <linux/major.h>                           // MD_MAJOR
#include <linux/raid/md_p.h>                       // MD_DISK_ACTIVE, etc.
#include <linux/raid/md_u.h>                       // constants for ioctl on
                                                   // raid
#include <stdio.h>
#include <sys/ioctl.h>                             // _IOR etc.
#include <unistd.h>                                // close


int    AddDisk(int  DiskMajor, int  DiskMinor, int  DiskIndex);
int    CloseRaid(void);
int   hFile = -1;                                  // avoid closing stdin !
int    OpenRaid(int Md);
void   PrintUsage(void);


int  AddDisk(int  DiskMajor, int  DiskMinor, int  DiskIndex) {
  // * after calling this function successfully, (kernel-2.4.37) the corres-
  //   ponding disk appears in "/proc/mdstat" under the corresponding md as
  //   disk.

  mdu_disk_info_t Disk;
  int             State;

  State          = (1 << MD_DISK_SYNC) | (1 << MD_DISK_ACTIVE);
                                                   // active disk
  printf("DiskIndex: %i\n", DiskIndex);

  Disk.number    = DiskIndex;                    // starts with 0 .
  Disk.major     = DiskMajor;
  Disk.minor     = DiskMinor;
  Disk.raid_disk = DiskIndex;                    // starts with 0 .
  Disk.state     = State;
    // * active disk: "(1 << MD_DISK_SYNC) | (1 << MD_DISK_ACTIVE)
    //                                    ev.: | (1 << MD_DISK_WRITEMOSTLY);"
    // * spare-disk: 0;

  if( ioctl(hFile, ADD_NEW_DISK, &Disk) ) {
    // it is an error.
      printf("errno = %i\n", errno);
      return -1;
  } // else
    DiskIndex++;
    return 0;
}


int  CloseRaid(void) {
  if(-1 != hFile) {
    // avoid closing a null-hFile .
      if( close(hFile) ) {
        // it is an error.
          printf("errno = %i\n", errno);
          return -1;
      } // else
  }
  return 0;
}


int main( int  argc, char*  argv[] ) {
  int  DiskIndex;
  int  DiskMajor;
  int  DiskMinor;
  int  MdMinor;

  if( (1 + 4) !=  argc) {
    // printf("argc = %i\n", argc);
    PrintUsage();
    return 0;
  } // else

  DiskMajor = strtol( argv[1], NULL, 10);
  DiskMinor = strtol( argv[2], NULL, 10);
  DiskIndex = strtol( argv[4], NULL, 10);
  MdMinor   = strtol( argv[3], NULL, 10);

  /* debug stuff:
    printf("%i\n", DiskMajor);
    printf("%i\n", DiskMinor);
    printf("%i\n", MdMinor);
    printf("%i\n", DiskIndex);
   */

  if( OpenRaid(MdMinor) )
      // it is an error.
        return 255;
    // else

  if( AddDisk(DiskMajor, DiskMinor, DiskIndex) ) {
      // it is an error.
        if( CloseRaid() )
            // it is an error.
              return 253;
          // else
        return 254;
  } // else

  if( CloseRaid() )
      // it is an error.
        return 253;
    // else
      return 0;
}


int  OpenRaid(int Md) {
  // * ok: Md in [0, 255]sub(N) (the device must exist in "/dev".).
  // * you may open successfully a raid-device ("/dev/md*") that is not yet
  //   started.
  // * kernel > kernel-2.6:  after calling this function successfully, the
  //   corresponding md is visible in "/sys/block".

  int    MdMinor;
  char  pStringBuffer[1024];

  MdMinor = Md;

  // md# --> String:
    sprintf(pStringBuffer, "/dev/md%i", MdMinor);

  hFile = open(pStringBuffer, O_RDWR);
  if(-1 == hFile) {
    // it is an error.
      printf("errno = %i\n", errno);
      return -1;
  } // else
    return 0;
}


void  PrintUsage(void) {
  printf("Usage: AddDisk  <Disk Major> <Disk Minor> <Raid# = md_Minor> <Disk Index>\n");
}