rom/dos/fread.c

   1 /*
   2     Copyright © 1995-2014, The AROS Development Team. All rights reserved.
   3     $Id$
   4
   5     Desc:
   6     Lang: english
   7 */
   8 #include <aros/debug.h>
   9
  10 #include "dos_intern.h"
  11
  12 #define FETCHERR    (-2)
  13
  14 /*****************************************************************************
  15
  16     NAME */
  17 #include <proto/dos.h>
  18
  19         AROS_LH4(LONG, FRead,
  20
  21 /*  SYNOPSIS */
  22         AROS_LHA(BPTR , fh, D1),
  23         AROS_LHA(APTR , block, D2),
  24         AROS_LHA(ULONG, blocklen, D3),
  25         AROS_LHA(ULONG, number, D4),
  26
  27 /*  LOCATION */
  28         struct DosLibrary *, DOSBase, 54, Dos)
  29
  30 /*  FUNCTION
  31         Read a number of blocks from a file.
  32         The read is buffered.
  33
  34     INPUTS
  35         fh - Read from this file
  36         block - The data is put here
  37         blocklen - This is the size of a single block
  38         number - The number of blocks
  39
  40     RESULT
  41         The number of blocks read from the file or 0 on EOF.
  42         This function may return fewer than the requested number of blocks.
  43         IoErr() gives additional information in case of an error.
  44
  45     NOTES
  46
  47     EXAMPLE
  48
  49     BUGS
  50
  51     SEE ALSO
  52         Open(), FWrite(), FPutc(), Close()
  53
  54     INTERNALS
  55
  56 *****************************************************************************/
  57 {
  58     AROS_LIBFUNC_INIT
  59
  60     UBYTE  *ptr;
  61     LONG    res = 0;
  62     ULONG   fetchsize = number * blocklen;
  63     ULONG   readsize;
  64
  65     ptr = block;
  66
  67     SetIoErr(0);
  68
  69     if((fetchsize == 0) || (fh == BNULL))
  70         return 0;
  71
  72     while(fetchsize > 0)
  73     {
  74         res = vbuf_fetch(fh, ptr, fetchsize, DOSBase);
  75         if (res < 0)
  76             break;
  77         ptr += res;
  78         fetchsize -= res;
  79     }
  80
  81     if(res == FETCHERR)
  82     {
  83         return EOF;
  84     }
  85
  86     readsize = (ULONG)(ptr - (UBYTE *)block);
  87
  88     return (LONG)(readsize / blocklen);
  89
  90     AROS_LIBFUNC_EXIT
  91 } /* FRead */
  92
  93 static LONG handle_write_mode(BPTR file, struct DosLibrary * DOSBase)
  94 {
  95     struct FileHandle *fh = (struct FileHandle *)BADDR(file);
  96
  97     /* If the file is in write mode... */
  98     if(fh->fh_Flags & FHF_WRITE)
  99     {
 100         /* write the buffer (in many pieces if the first one isn't enough). */
 101         LONG pos = 0;
 102
 103         while(pos != fh->fh_Pos)
 104         {
 105             LONG size = Write(file, BADDR(fh->fh_Buf) + pos, fh->fh_Pos - pos);
 106
 107             /* An error happened? Return it. */
 108             if(size < 0)
 109             {
 110                 return FETCHERR;
 111             }
 112
 113             pos += size;
 114         }
 115
 116         /* Reinit filehandle. */
 117         fh->fh_Flags &= ~FHF_WRITE;
 118         fh->fh_Pos = fh->fh_End = 0;
 119     }
 120
 121     return 0;
 122 }
 123
 124 /* Fetches up to remaining buffer content from file buffer
 125  * Return values:
 126  *  (-2) on error
 127  *  (EOF) on EOF
 128  *  (>0) on successful fetch
 129  */
 130 LONG vbuf_fetch(BPTR file, UBYTE * buffer, ULONG fetchsize, struct DosLibrary *DOSBase)
 131 {
 132     /* Get pointer to filehandle */
 133     struct FileHandle *fh = (struct FileHandle *)BADDR(file);
 134
 135     LONG  size;
 136     LONG  bufsize;
 137
 138     if (fh == NULL)
 139     {
 140         return FETCHERR;
 141     }
 142
 143     if (handle_write_mode(file, DOSBase) == FETCHERR)
 144     {
 145         return FETCHERR;
 146     }
 147
 148     /* No normal characters left. */
 149     if(fh->fh_Pos >= fh->fh_End)
 150     {
 151         /* Check for a pushed back EOF. */
 152         if(fh->fh_Pos > fh->fh_End)
 153         {
 154             D(bug("FGetC: Weird pos: fh_Pos (%d) > fh_End (%d)\n", fh->fh_Pos, fh->fh_End));
 155             /* Return EOF. */
 156             return EOF;
 157         }
 158
 159         /* Is there a buffer? */
 160         if(fh->fh_Buf == BNULL)
 161         {
 162             if (NULL == vbuf_alloc(fh, NULL, IOBUFSIZE))
 163             {
 164                 D(bug("FGetC: Can't allocate buffer\n"));
 165                 return FETCHERR;
 166             }
 167         }
 168
 169         /* Fill the buffer. */
 170         if (fh->fh_Buf != fh->fh_OrigBuf) {
 171             D(bug("FGetC: Can't trust fh_BufSize. Using 208 as the buffer size.\n"));
 172             bufsize = 208;
 173         } else {
 174             bufsize = fh->fh_BufSize;
 175         }
 176         size = Read(file, BADDR(fh->fh_Buf), bufsize);
 177
 178         /* Prepare filehandle for data. */
 179         if(size <= 0)
 180             size = 0;
 181
 182         fh->fh_Pos = 0;
 183         fh->fh_End = size;
 184
 185         /* No data read? Return EOF. */
 186         if(size == 0)
 187         {
 188             D(bug("FGetC: Tried to Read() to a %d byte buffer, got 0)\n", bufsize));
 189             return EOF;
 190         }
 191     }
 192
 193     /* If fh_End == 0, simulate an EOF */
 194     if (fh->fh_End == 0) {
 195         D(bug("FGetC: Got an EOF via fh_End == 0\n"));
 196         return EOF;
 197     }
 198
 199     /* All OK. Get requested data. */
 200     size = fh->fh_End - fh->fh_Pos;
 201     if (size > fetchsize) size = fetchsize;
 202     if (size == 1) /* Don't do function call for 1 byte reads */
 203         *buffer = ((UBYTE *)BADDR(fh->fh_Buf))[fh->fh_Pos];
 204     else
 205         CopyMem(((UBYTE *)BADDR(fh->fh_Buf)) + fh->fh_Pos, buffer, size);
 206
 207     fh->fh_Pos += size;
 208
 209     return size;
 210 }