1  #include "buffer_entry.h"
       2  #include <stdio.h>
       3  #include <assert.h>
       4  #include <stdlib.h>
       5  #include <string.h>
       6  
       7  struct __buffer_entry_t
       8  {
       9  	FILE *fd;
      10  	cmph_uint8 * buff;
      11  	cmph_uint32 capacity, // buffer entry capacity
      12  		    nbytes,   // buffer entry used bytes
      13  		    pos;      // current read position in buffer entry
      14  	cmph_uint8  eof;      // flag to indicate end of file
      15  };
      16  
      17  buffer_entry_t * buffer_entry_new(cmph_uint32 capacity)
      18  {
      19  	buffer_entry_t *buff_entry = (buffer_entry_t *)malloc(sizeof(buffer_entry_t));
      20  	assert(buff_entry);
      21  	buff_entry->fd = NULL;
      22  	buff_entry->buff = NULL;
      23  	buff_entry->capacity = capacity;
      24  	buff_entry->nbytes = capacity;
      25  	buff_entry->pos = capacity;
      26          buff_entry->eof = 0;
      27  	return buff_entry;
      28  }
      29  
      30  void buffer_entry_open(buffer_entry_t * buffer_entry, char * filename)
      31  {
      32  	buffer_entry->fd = fopen(filename, "rb");
      33  }
      34  
      35  void buffer_entry_set_capacity(buffer_entry_t * buffer_entry, cmph_uint32 capacity)
      36  {
      37  	buffer_entry->capacity = capacity;
      38  }
      39  
      40  
      41  cmph_uint32 buffer_entry_get_capacity(buffer_entry_t * buffer_entry)
      42  {
      43  	return buffer_entry->capacity;
      44  }
      45  
      46  static void buffer_entry_load(buffer_entry_t * buffer_entry)
      47  {
      48  	free(buffer_entry->buff);
      49  	buffer_entry->buff = (cmph_uint8 *)calloc((size_t)buffer_entry->capacity, sizeof(cmph_uint8));
      50  	buffer_entry->nbytes = (cmph_uint32)fread(buffer_entry->buff, (size_t)1, (size_t)buffer_entry->capacity, buffer_entry->fd);
      51  	if (buffer_entry->nbytes != buffer_entry->capacity) buffer_entry->eof = 1;
      52  	buffer_entry->pos = 0;
      53  }
      54  
      55  cmph_uint8 * buffer_entry_read_key(buffer_entry_t * buffer_entry, cmph_uint32 * keylen)
      56  {
      57  	cmph_uint8 * buf = NULL;
      58  	cmph_uint32 lacked_bytes = sizeof(*keylen);
      59  	cmph_uint32 copied_bytes = 0;
      60  	if(buffer_entry->eof && (buffer_entry->pos == buffer_entry->nbytes)) // end
      61  	{
      62  		free(buf);
      63  		return NULL;
      64  	}
      65  	if((buffer_entry->pos + lacked_bytes) > buffer_entry->nbytes) 
      66  	{
      67  		copied_bytes = buffer_entry->nbytes - buffer_entry->pos;
      68  		lacked_bytes = (buffer_entry->pos + lacked_bytes) - buffer_entry->nbytes;
      69  		if (copied_bytes != 0) memcpy(keylen, buffer_entry->buff + buffer_entry->pos, (size_t)copied_bytes);
      70  		buffer_entry_load(buffer_entry);
      71  	}
      72  	memcpy(keylen + copied_bytes, buffer_entry->buff + buffer_entry->pos, (size_t)lacked_bytes);
      73  	buffer_entry->pos += lacked_bytes;
      74  	
      75  	lacked_bytes = *keylen;
      76  	copied_bytes = 0;
      77  	buf = (cmph_uint8 *)malloc(*keylen + sizeof(*keylen));
      78          memcpy(buf, keylen, sizeof(*keylen));
      79  	if((buffer_entry->pos + lacked_bytes) > buffer_entry->nbytes) {
      80  		copied_bytes = buffer_entry->nbytes - buffer_entry->pos;
      81  		lacked_bytes = (buffer_entry->pos + lacked_bytes) - buffer_entry->nbytes;
      82  		if (copied_bytes != 0) {
      83  			memcpy(buf + sizeof(*keylen), buffer_entry->buff + buffer_entry->pos, (size_t)copied_bytes);
      84                  }
      85  		buffer_entry_load(buffer_entry);
      86  	}        
      87  	memcpy(buf+sizeof(*keylen)+copied_bytes, buffer_entry->buff + buffer_entry->pos, (size_t)lacked_bytes);
      88  	buffer_entry->pos += lacked_bytes;
      89  	return buf;
      90  }
      91  
      92  void buffer_entry_destroy(buffer_entry_t * buffer_entry)
      93  {
      94    fclose(buffer_entry->fd);
      95    buffer_entry->fd = NULL;
      96    free(buffer_entry->buff);
      97    buffer_entry->buff = NULL;
      98    buffer_entry->capacity = 0;
      99    buffer_entry->nbytes = 0;
     100    buffer_entry->pos = 0;  
     101    buffer_entry->eof = 0;
     102    free(buffer_entry);
     103  }