2.11BSD#431 - /usr/src/local/mtools/file_read.c

   1: #include <stdio.h>
   2: #include "msdos.h"
   3: 
   4: extern int clus_size, dir_start, dir_len, fat_error;
   5: extern unsigned int last_fat;
   6: 
   7: /*
   8:  * Read the clusters given the beginning FAT entry.  Returns 0 on success.
   9:  */
  10: 
  11: int
  12: file_read(fp, fat, textmode, stripmode, size)
  13: FILE *fp;
  14: unsigned int fat;
  15: int textmode, stripmode;
  16: long size;
  17: {
  18:     register int i;
  19:     int in_len, out_len;
  20:     unsigned int fat_decode();
  21:     long current, start;
  22:     unsigned char in_buf[MAX_CLUSTER], out_buf[MAX_CLUSTER];
  23:     void disk_read(), perror();
  24: 
  25:     current = 0L;
  26:     in_len = clus_size * MSECTOR_SIZE;
  27:                     /* a zero length file? */
  28:     if (fat == 0)
  29:         return(0);
  30: 
  31:     /* CONSTCOND */
  32:     while (1) {
  33:         start = (long) (fat - 2) * clus_size + dir_start + dir_len;
  34:         disk_read(start, in_buf, in_len);
  35: 
  36:                     /* do the translations */
  37:         if (textmode || stripmode) {
  38:             out_len = 0;
  39:             for (i = 0; i < in_len; i++) {
  40:                 current++;
  41:                 if (current > size)
  42:                     break;
  43:                 if (textmode && in_buf[i] == '\r')
  44:                     continue;
  45:                 if (textmode && current == size && in_buf[i] == 0x1a)
  46:                     continue;
  47:                 if (stripmode)
  48:                     out_buf[out_len++] = in_buf[i] & 0x7f;
  49:                 else
  50:                     out_buf[out_len++] = in_buf[i];
  51:             }
  52:                     /* write it */
  53:             if (fwrite((char *) out_buf, sizeof(*out_buf), out_len, fp) == 0) {
  54:                 perror("file_write: fwrite");
  55:                 return(-1);
  56:             }
  57:         }
  58:                     /* much easier... */
  59:         else {
  60:             out_len = (size - current > in_len) ? in_len : size - current;
  61:             if (fwrite((char *) in_buf, sizeof(*in_buf), out_len, fp) == 0) {
  62:                 perror("file_write: fwrite");
  63:                 return(-1);
  64:             }
  65: 
  66:             current += out_len;
  67:             if (current >= size)
  68:                 break;
  69:         }
  70: 
  71:                     /* get next cluster number */
  72:         fat = fat_decode(fat);
  73:         if (fat == 1) {
  74:             fprintf(stderr, "file_read: FAT problem\n");
  75:             fat_error++;
  76:             return(-1);
  77:         }
  78:                     /* end of cluster chain */
  79:         if (fat >= last_fat)
  80:             break;
  81:     }
  82:     return(0);
  83: }

Defined functions