Simple-LogFS/disk.c at main · jnin-dev/Simple-LogFS · GitHub

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

#include "disk.h"

#define DISK_MAGIC 0xdeadbeef

static FILE *diskfile;
static int nblocks = 0;
static int nreads = 0;
static int nwrites = 0;

int disk_init(const char *filename, int n)
{
    diskfile = fopen(filename, "r+");
    if (!diskfile)
        diskfile = fopen(filename, "w+");
    if (!diskfile)
        return 0;

    ftruncate(fileno(diskfile), n * DISK_BLOCK_SIZE);

    nblocks = n;
    nreads = 0;
    nwrites = 0;

    return 1;
}

int disk_size()
{
    return nblocks;
}

static void sanity_check(int blocknum, const void *data)
{
    if (blocknum < 0)
    {
        printf("ERROR: blocknum (%d) is negative!\n", blocknum);
        abort();
    }

    if (blocknum >= nblocks)
    {
        printf("ERROR: blocknum (%d) is too big!\n", blocknum);
        abort();
    }

    if (!data)
    {
        printf("ERROR: null data pointer!\n");
        abort();
    }
}

void disk_read(int blocknum, char *data)
{
    sanity_check(blocknum, data);

    fseek(diskfile, blocknum * DISK_BLOCK_SIZE, SEEK_SET);

    if (fread(data, DISK_BLOCK_SIZE, 1, diskfile) == 1)
    {
        nreads++;
    }
    else
    {
        printf("ERROR: couldn't access simulated disk: %s\n", strerror(errno));
        abort();
    }
}

void disk_write(int blocknum, const char *data)
{
    sanity_check(blocknum, data);

    fseek(diskfile, blocknum * DISK_BLOCK_SIZE, SEEK_SET);

    if (fwrite(data, DISK_BLOCK_SIZE, 1, diskfile) == 1)
    {
        nwrites++;
    }
    else
    {
        printf("ERROR: couldn't access simulated disk: %s\n", strerror(errno));
        abort();
    }
}

void disk_close()
{
    if (diskfile)
    {
        printf("%d disk block reads\n", nreads);
        printf("%d disk block writes\n", nwrites);
        fclose(diskfile);
        diskfile = 0;
    }
}