posix/lib/psxdll/unistd/read.c

   1 /* $Id: read.c,v 1.2 2002/03/21 22:46:30 hyperion Exp $
   2  */
   3 /*
   4  * COPYRIGHT:   See COPYING in the top level directory
   5  * PROJECT:     ReactOS POSIX+ Subsystem
   6  * FILE:        subsys/psx/lib/psxdll/unistd/read.c
   7  * PURPOSE:     Read from a file
   8  * PROGRAMMER:  KJK::Hyperion <noog@libero.it>
   9  * UPDATE HISTORY:
  10  *              15/02/2002: Created
  11  */
  12
  13 #include <ddk/ntddk.h>
  14 #include <fcntl.h>
  15 #include <unistd.h>
  16 #include <sys/types.h>
  17 #include <psx/debug.h>
  18 #include <psx/errno.h>
  19
  20 ssize_t __read(int fildes, void *buf, size_t nbyte, off_t *offset)
  21 {
  22  HANDLE          hFile;
  23  NTSTATUS        nErrCode;
  24  IO_STATUS_BLOCK isbStatus;
  25
  26  /* get the file handle for the specified file descriptor */
  27  if(fcntl(fildes, F_GETFH, &hFile) == -1)
  28   return (-1);
  29
  30  if(offset != NULL)
  31  {
  32   /* NT always moves the file pointer, while Unix pread() must not: we have to
  33      duplicate the handle and work on the duplicate */ /* FIXME? better save
  34      the file position and restore it later? */
  35   HANDLE hDupFile;
  36
  37   /* duplicate the handle */
  38   nErrCode = NtDuplicateObject
  39   (
  40    NtCurrentProcess(),
  41    hFile,
  42    NtCurrentProcess(),
  43    &hDupFile,
  44    0,
  45    0,
  46    DUPLICATE_SAME_ACCESS
  47   );
  48
  49   /* failure */
  50   if(!NT_SUCCESS(nErrCode))
  51   {
  52    errno = __status_to_errno(nErrCode);
  53    return (0);
  54   }
  55
  56   /* read data from file at the specified offset */
  57   nErrCode = NtReadFile
  58   (
  59    hDupFile,
  60    NULL,
  61    NULL,
  62    NULL,
  63    &isbStatus,
  64    buf,
  65    nbyte,
  66    (PLARGE_INTEGER)offset,
  67    NULL
  68   );
  69
  70   NtClose(hDupFile);
  71
  72   /* failure */
  73   if(!NT_SUCCESS(nErrCode))
  74   {
  75    errno = __status_to_errno(nErrCode);
  76    return (0);
  77   }
  78  }
  79  else
  80  {
  81   /* read data from file at the current offset */
  82   nErrCode = NtReadFile
  83   (
  84    hFile,
  85    NULL,
  86    NULL,
  87    NULL,
  88    &isbStatus,
  89    buf,
  90    nbyte,
  91    NULL,
  92    NULL
  93   );
  94
  95   /* failure */
  96   if(!NT_SUCCESS(nErrCode))
  97   {
  98    errno = __status_to_errno(nErrCode);
  99    return (0);
 100   }
 101  }
 102
 103  return ((ssize_t)isbStatus.Information);
 104 }
 105
 106 ssize_t read(int fildes, void *buf, size_t nbyte)
 107 {
 108  return (__read(fildes, buf, nbyte, NULL));
 109 }
 110
 111 ssize_t pread(int fildes, void *buf, size_t nbyte, off_t offset)
 112 {
 113  return (__read(fildes, buf, nbyte, &offset));
 114 }
 115
 116 /* EOF */
 117