Fast file read in Linux

linux_io.c

#include "linux_io.h"

#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <wchar.h>

int main(void)
{
	char *buffer;
	size_t l;
	int i;


	buffer = (char*)malloc(BUFFER_SIZE + 1);

	int fd;
	fd = open("../../dataset/dataset.txt", O_RDONLY);

	l = f_read(fd, buffer);
	printf("Bytes read: %lu\n",l);

	printf("Bytes printed: %lu\n", strlen(buffer));
	printf("%lu\n", strlen(buffer));

	printf("%s\n", buffer);

	free(buffer);
	return 0;
}

linux_io.h

#ifndef __LINUX_IO__
#define __LINUX_IO__

#include <string.h>
#include <stdlib.h>
#include <stdio.h>

#ifdef __linux__
#include <unistd.h>
#include <fcntl.h>
#endif

//Consts
#define BLKSIZE 4096
#define BUFFER_SIZE (2 * 4096)//(16 * 1024)

size_t f_read(int, char*);

/**
* Reads a file specified by it's file descriptor and stores contents into a PRE-ALLOCATED buffer
* Return value: total number of bytes read
*/
size_t f_read(int fd, char *buffer)
{
	//Get file descriptor by 'open' system call. -1 indicates error
	if(fd == -1)
		return fd;
	else
	{
		#ifdef __linux__
		//Advise the kernel on read for optimizations
		posix_fadvise(fd, 0, 0, POSIX_FADV_SEQUENTIAL);

		size_t bytes_read;
		size_t total_bytes = 0;

		while((bytes_read = read(fd, buffer, BUFFER_SIZE)))
		{
			if(!bytes_read)
				break;
			total_bytes += bytes_read;
		}

		buffer[BUFFER_SIZE] = '\0';
		//printf(L"%s\n", buffer);
		#endif

		return total_bytes;

	}

}

#endif