* fhandler_floppy.cc (fhandler_dev_floppy::lseek): Determine

drive geometry or partition size to allow seeking from the end of
raw floppy device. Don't allow positioning past the end of media or
to offsets bigger then max off_t.

1 files changed, 84 insertions, 47 deletions

diff --git a/winsup/cygwin/fhandler_floppy.cc b/winsup/cygwin/fhandler_floppy.cc
index a767443..bab0b0a 100644
--- a/winsup/cygwin/fhandler_floppy.cc
+++ b/winsup/cygwin/fhandler_floppy.cc
@@ -16,6 +16,7 @@ details. */
 #include <unistd.h>
 #include "fhandler.h"
 #include "cygerrno.h"
+#include <winioctl.h>
 
 /**********************************************************************/
 /* fhandler_dev_floppy */
@@ -80,78 +81,114 @@ off_t
 fhandler_dev_floppy::lseek (off_t offset, int whence)
 {
   int ret;
-  DWORD off;
   char buf[512];
-
-  if (whence == SEEK_SET)
+  long long drive_size = 0;
+  long long lloffset = offset;
+  long long current_position;
+  off_t sector_aligned_offset;
+  off_t bytes_left;
+  DWORD low;
+  LONG high = 0;
+
+  if (os_being_run == winNT)
     {
-      if (offset < 0)
+      DISK_GEOMETRY di;
+      PARTITION_INFORMATION pi;
+      DWORD bytes_read;
+
+      if ( !DeviceIoControl ( get_handle(),
+                              IOCTL_DISK_GET_DRIVE_GEOMETRY,
+                              NULL, 0,
+                              &di, sizeof (di),
+                              &bytes_read, NULL) )
         {
-	  set_errno (EINVAL);
-	  return -1;
-	}
-
-      /* Invalidate buffer. */
-      ret = writebuf ();
-      if (ret)
-	return ret;
-      devbufstart = devbufend = 0;
-
-      off = (offset / 512) * 512;
-
-      if (SetFilePointer (get_handle (), off, NULL, FILE_BEGIN)
-          == INVALID_SET_FILE_POINTER)
+          __seterrno ();
+          return -1;
+        }
+      debug_printf ( "disk geometry: (%ld cyl)*(%ld trk)*(%ld sec)*(%ld bps)",
+                     di.Cylinders.LowPart,
+                     di.TracksPerCylinder,
+                     di.SectorsPerTrack,
+                     di.BytesPerSector );
+      if ( DeviceIoControl ( get_handle (),
+                             IOCTL_DISK_GET_PARTITION_INFO,
+                             NULL, 0,
+                             &pi, sizeof (pi),
+                             &bytes_read, NULL ))
         {
-	  __seterrno ();
-	  return -1;
-	}
-      return raw_read (buf, offset - off);
+          debug_printf ( "partition info: %ld (%ld)",
+                          pi.StartingOffset.LowPart,
+                          pi.PartitionLength.LowPart);
+          drive_size = (long long) pi.PartitionLength.QuadPart;
+        }
+      else
+        {
+          drive_size = (long long) di.Cylinders.QuadPart * di.TracksPerCylinder *
+                       di.SectorsPerTrack * di.BytesPerSector;
+        }
+      debug_printf ( "drive size: %ld", drive_size );
     }
-  else if (whence == SEEK_CUR)
+
+  if (whence == SEEK_END && drive_size > 0)
     {
-      DWORD low;
-      LONG high = 0;
+      lloffset = offset + drive_size;
+      whence = SEEK_SET; 
+    }
 
+  if (whence == SEEK_CUR)
+    {
       low = SetFilePointer (get_handle (), 0, &high, FILE_CURRENT);
       if (low == INVALID_SET_FILE_POINTER && GetLastError ())
 	{
 	  __seterrno ();
 	  return -1;
 	}
-      long long cur = (long long) high << 32 + low;
+      current_position = (long long) low + ((long long) high << 32);
       if (is_writing)
-	cur += devbufend - devbufstart;
+	current_position += devbufend - devbufstart;
       else
-	cur -= devbufend - devbufstart;
-      
+	current_position -= devbufend - devbufstart;
+
+      lloffset += current_position;
+      whence = SEEK_SET;
+    }
+
+  if (lloffset < 0 ||
+      drive_size > 0 && lloffset > drive_size)
+    {
+      set_errno (EINVAL);
+      return -1;
+    }
+  high = lloffset >> 32;
+  low = lloffset & 0xffffffff;
+  if ( high || (off_t) low < 0 )
+    {
+      set_errno (EFBIG);
+      return -1;
+    }
+  offset = (off_t) low;
+
+  /* FIXME: sector can possibly be not 512 bytes long */
+  sector_aligned_offset = (offset / 512) * 512;
+  bytes_left = offset - sector_aligned_offset;
+
+  if (whence == SEEK_SET)
+    {
       /* Invalidate buffer. */
       ret = writebuf ();
       if (ret)
 	return ret;
       devbufstart = devbufend = 0;
 
-      cur += offset;
-      if (cur < 0)
-	{
-	  set_errno (EINVAL);
-	  return -1;
-	}
-
-      long long set = (cur / 512) * 512;
-      high = set >> 32;
-      low = set & 0xffffffff;
-
-      off = cur - set;
-
-      low = SetFilePointer (get_handle (), low, &high, FILE_BEGIN);
-      if (low == INVALID_SET_FILE_POINTER && GetLastError ())
-	{
+      if (SetFilePointer (get_handle (), sector_aligned_offset, NULL, FILE_BEGIN)
+          == INVALID_SET_FILE_POINTER)
+        {
 	  __seterrno ();
 	  return -1;
 	}
-      return raw_read (buf, off);
+      return sector_aligned_offset + raw_read (buf, bytes_left);
     }
-  /* SEEK_END is not supported on raw disk devices. */
+
   set_errno (EINVAL);
   return -1;
 }