reactos操作系统实现(56)

 

在Reactos安装过程里，会出现下面的界面，如下：

 

上面的界面就是创建磁盘分区显示的内容，那么这个界面下面主要做了那些工作呢？磁盘又是怎么样分区的呢？分区后的数据怎么样保存到磁盘里的呢？接着下来，就分析创建磁盘分区的代码，才能知道整个实现过程，如下：

#001  static PAGE_NUMBER

#002  CreatePartitionPage (PINPUT_RECORD Ir)

#003  {

 

当按下回车键时，就会调用这个函数执行创建分区的动作。

#004      PDISKENTRY DiskEntry;

#005      PPARTENTRY PartEntry;

#006      BOOLEAN Quit;

#007      BOOLEAN Cancel;

#008      CHAR InputBuffer[50];

#009      ULONG MaxSize;

#010      ULONGLONG PartSize;

#011      ULONGLONG DiskSize;

#012      PCHAR Unit;

#013 

 

判断分区表是否为空。

#014      if (PartitionList == NULL ||

#015          PartitionList->CurrentDisk == NULL ||

#016          PartitionList->CurrentPartition == NULL)

#017      {

#018          /* FIXME: show an error dialog */

#019          return QUIT_PAGE;

#020      }

#021 

 

获取当前磁盘和当前分区。

#022      DiskEntry = PartitionList->CurrentDisk;

#023      PartEntry = PartitionList->CurrentPartition;

#024 

#025      CONSOLE_SetStatusText(MUIGetString(STRING_PLEASEWAIT));

#026 

#027      CONSOLE_SetTextXY(6, 8, MUIGetString(STRING_CHOOSENEWPARTITION));

#028 

#029  #if 0

#030      if (DiskEntry->DiskSize >= 0x280000000ULL) /* 10 GB */

#031      {

#032          DiskSize = (DiskEntry->DiskSize + (1 << 29)) >> 30;

#033          Unit = MUIGetString(STRING_GB);

#034      }

#035      else

#036  #endif

#037      {

 

获取磁盘的大小。

#038          DiskSize = (DiskEntry->DiskSize + (1 << 19)) >> 20;

#039 

#040          if (DiskSize == 0)

#041              DiskSize = 1;

#042 

#043          Unit = MUIGetString(STRING_MB);

#044      }

#045 

#046      if (DiskEntry->DriverName.Length > 0)

#047      {

#048          CONSOLE_PrintTextXY(6, 10,

#049                               MUIGetString(STRING_HDINFOPARTCREATE),

#050                               DiskSize,

#051                               Unit,

#052                               DiskEntry->DiskNumber,

#053                               DiskEntry->Port,

#054                               DiskEntry->Bus,

#055                               DiskEntry->Id,

#056                               &DiskEntry->DriverName);

#057      }

#058      else

#059      {

#060          CONSOLE_PrintTextXY(6, 10,

#061                               MUIGetString(STRING_HDDINFOUNK1),

#062                               DiskSize,

#063                               Unit,

#064                               DiskEntry->DiskNumber,

#065                               DiskEntry->Port,

#066                               DiskEntry->Bus,

#067                               DiskEntry->Id);

#068      }

#069 

#070      CONSOLE_SetTextXY(6, 12, MUIGetString(STRING_HDDSIZE));

#071 

#072  #if 0

#073      CONSOLE_PrintTextXY(8, 10, "Maximum size of the new partition is %I64u MB",

#074                           PartitionList->CurrentPartition->UnpartitionedLength / (1024*1024));

#075  #endif

#076 

#077      CONSOLE_SetStatusText(MUIGetString(STRING_CREATEPARTITION));

#078 

 

循环地处理创建分区。

#079      PartEntry = PartitionList->CurrentPartition;

#080      while (TRUE)

#081      {

#082          MaxSize = (PartEntry->UnpartitionedLength + (1 << 19)) >> 20;  /* in MBytes (rounded) */

#083 

#084          if (MaxSize > PARTITION_MAXSIZE) MaxSize = PARTITION_MAXSIZE;

#085 

 

获取用户输入分区的大小，比如输入多少M磁盘大小。

#086          ShowPartitionSizeInputBox (12, 14, xScreen - 12, 17, /* left, top, right, bottom */

#087                                     MaxSize, InputBuffer, &Quit, &Cancel);

#088 

#089          if (Quit == TRUE)

#090          {

#091              if (ConfirmQuit (Ir) == TRUE)

#092              {

#093                  return QUIT_PAGE;

#094              }

#095          }

#096          else if (Cancel == TRUE)

#097          {

#098              return SELECT_PARTITION_PAGE;

#099          }

#100          else

#101          {

 

 

根据输入的字符串来计算分区的大小。

#102              PartSize = atoi(InputBuffer);

#103 

#104              if (PartSize < 1)

#105              {

#106                  /* Too small */

#107                  continue;

#108              }

#109 

#110              if (PartSize > MaxSize)

#111              {

#112                  /* Too large */

#113                  continue;

#114              }

#115 

 

下面把输入以MB为单位的大小转换为以字节为大小。

#116              /* Convert to bytes */

#117              if (PartSize == MaxSize)

#118              {

#119                  /* Use all of the unpartitioned disk space */

#120                  PartSize = PartEntry->UnpartitionedLength;

#121              }

#122              else

#123              {

#124                  /* Round-up by cylinder size */

#125                  PartSize = ROUND_UP (PartSize * 1024 * 1024,

#126                                       DiskEntry->CylinderSize);

#127 

#128                  /* But never get larger than the unpartitioned disk space */

#129                  if (PartSize > PartEntry->UnpartitionedLength)

#130                      PartSize = PartEntry->UnpartitionedLength;

#131              }

#132 

#133              DPRINT ("Partition size: %I64u bytes/n", PartSize);

#134 

 

调用函数CreateNewPartition创建一个分区。

#135              CreateNewPartition (PartitionList,

#136                                  PartSize,

#137                                  FALSE);

#138 

#139              return SELECT_PARTITION_PAGE;

#140          }

#141      }

#142 

#143      return CREATE_PARTITION_PAGE;

#144  }