git.sur5r.net Git - cc65/blob - libsrc/apple2/readdir.c

   1 /*****************************************************************************/
   2 /*                                                                           */
   3 /*                                readdir.c                                  */
   4 /*                                                                           */
   5 /*                           Read directory entry                            */
   6 /*                                                                           */
   7 /*                                                                           */
   8 /*                                                                           */
   9 /* (C) 2005  Oliver Schmidt, <ol.sc@web.de>                                  */
  10 /*                                                                           */
  11 /*                                                                           */
  12 /* This software is provided 'as-is', without any expressed or implied       */
  13 /* warranty.  In no event will the authors be held liable for any damages    */
  14 /* arising from the use of this software.                                    */
  15 /*                                                                           */
  16 /* Permission is granted to anyone to use this software for any purpose,     */
  17 /* including commercial applications, and to alter it and redistribute it    */
  18 /* freely, subject to the following restrictions:                            */
  19 /*                                                                           */
  20 /* 1. The origin of this software must not be misrepresented; you must not   */
  21 /*    claim that you wrote the original software. If you use this software   */
  22 /*    in a product, an acknowledgment in the product documentation would be  */
  23 /*    appreciated but is not required.                                       */
  24 /* 2. Altered source versions must be plainly marked as such, and must not   */
  25 /*    be misrepresented as being the original software.                      */
  26 /* 3. This notice may not be removed or altered from any source              */
  27 /*    distribution.                                                          */
  28 /*                                                                           */
  29 /*****************************************************************************/
  30
  31
  32
  33 #include <stddef.h>
  34 #include <unistd.h>
  35 #include <dirent.h>
  36 #include <dir.h>
  37
  38
  39
  40 /*****************************************************************************/
  41 /*                                   Code                                    */
  42 /*****************************************************************************/
  43
  44
  45
  46 struct dirent* __fastcall__ readdir (DIR* dir)
  47 {
  48     unsigned char* entry;
  49
  50     /* Search for the next active directory entry */
  51     do {
  52
  53         /* Read next directory block if necessary */
  54         if (dir->current_entry == dir->entries_per_block) {
  55             if (read (dir->fd,
  56                       dir->block.bytes,
  57                       sizeof (dir->block)) != sizeof (dir->block)) {
  58
  59                 /* Just return failure as read() has */
  60                 /* set errno if (and only if) no EOF */
  61                 return NULL;
  62             }
  63
  64             /* Start with first entry in next block */
  65             dir->current_entry = 0;
  66         }
  67
  68         /* Compute pointer to current entry */
  69         entry = dir->block.content.entries +
  70                 dir->current_entry * dir->entry_length;
  71
  72         /* Switch to next entry */
  73         ++dir->current_entry;
  74     } while (entry[0] == 0);
  75
  76     /* Move creation date/time to allow for next step below */
  77     *(unsigned long*)&entry[0x1A] = *(unsigned long*)&entry[0x18];
  78
  79     /* Feature unsigned long access to EOF by extending from 3 to 4 bytes */
  80     entry[0x18] = 0;
  81
  82     /* Move file type to allow for next step below */
  83     entry[0x19] = entry[0x10];
  84
  85     /* Zero-terminate file name */
  86     entry[0x01 + (entry[0x00] & 0x0F)] = 0;
  87
  88     /* Return success */
  89     return (struct dirent*)&entry[0x01];
  90 }