stdio.c

   1 #include <console.h>
   2 #include <multiboot.h>
   3 #include <stdint.h>
   4 #include <stdio.h>
   5 #include <stdlib.h>
   6 #include <string.h>
   7
   8
   9 struct FILE {
  10     struct multiboot_module *mod;
  11     long loc;
  12 };
  13
  14
  15 extern struct multiboot_module *mboot_modules;
  16 extern int mboot_module_count;
  17
  18
  19 FILE *fopen(const char *path, const char *mode)
  20 {
  21     for (int i = 0; i < mboot_module_count; i++) {
  22         if (!strcmp(path, mboot_modules[i].cmdline)) {
  23             FILE *fp = malloc(sizeof(*fp));
  24             fp->mod = &mboot_modules[i];
  25             fp->loc = 0;
  26             return fp;
  27         }
  28     }
  29
  30     return NULL;
  31 }
  32
  33
  34 int fclose(FILE *stream)
  35 {
  36     free(stream);
  37     return 0;
  38 }
  39
  40
  41 size_t fread(void *ptr, size_t size, size_t nmemb, FILE *stream)
  42 {
  43     size_t byte_size = size * nmemb;
  44     size_t mod_len = stream->mod->mod_end - stream->mod->mod_start;
  45
  46     if (stream->loc > mod_len) {
  47         return 0;
  48     }
  49
  50     if (byte_size > mod_len - stream->loc) {
  51         byte_size = mod_len - stream->loc;
  52     }
  53     nmemb = byte_size / size;
  54     byte_size = nmemb * size;
  55
  56     memcpy(ptr, (uint8_t *)stream->mod->mod_start + stream->loc, byte_size);
  57     stream->loc += byte_size;
  58
  59     return nmemb;
  60 }
  61
  62
  63 long ftell(FILE *fp)
  64 {
  65     return fp->loc;
  66 }
  67
  68
  69 int fseek(FILE *stream, long offset, int whence)
  70 {
  71     switch (whence) {
  72         case SEEK_SET:
  73             stream->loc = offset;
  74             break;
  75
  76         case SEEK_CUR:
  77             stream->loc += offset;
  78             break;
  79
  80         case SEEK_END:
  81             stream->loc = stream->mod->mod_end - stream->mod->mod_start;
  82             stream->loc += offset;
  83             break;
  84     }
  85
  86     if (stream->loc < 0) {
  87         stream->loc = 0;
  88     }
  89
  90     return 0;
  91 }