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devpoke.c
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devpoke.c
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#define _GNU_SOURCE /* Berserk glibc headers: O_DIRECT not defined unless _GNU_SOURCE defined */
#include <stdio.h>
#include <stdlib.h>
#include <stddef.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
ssize_t pwrite(int fd, const void *buf, size_t count, off_t offset);
#define trace_on(args) args
#define trace_off(args)
#define BREAK asm("int3")
#define warn(string, args...) do { fprintf(stderr, "%s: " string "\n", __FILE__, ##args); } while (0)
#define error(string, args...) do { warn(string, ##args); BREAK; } while (0)
#define trace trace_on
void *malloc_aligned(size_t size, unsigned binalign)
{
unsigned long p = (unsigned long)malloc(size + binalign - 1);
return (void *)(p + (-p & (binalign - 1)));
}
int main(int argc, char *argv[])
{
int err, dev, iterations = 1, blockshift = 13, blocksize = 1 << blockshift;
char *buffer = malloc_aligned(blocksize, blocksize);
if (!(dev = open(argv[1], O_RDWR | O_DIRECT)))
error("Could not open %s", argv[1]);
if (argc < 3 || argc > 4)
error("usage: %s device read/write [iterations]", argv[0]);
if (argc > 3)
iterations = atoi(argv[3]);
int rw = !strcmp(argv[2], "write");
typeof(pread) *fn = rw? ((typeof(pread) *)pwrite): pread;
char *what = rw? "write": "read";
unsigned range = (lseek(dev, 0, SEEK_END) >> blockshift), total = 0;
printf("range = %u, iterations = %u\n", range, iterations);
while (iterations--) {
unsigned block = 1? (rand() % range): total;
trace(warn("%s block %x", what, block);)
if ((err = fn(dev, buffer, blocksize, block << blockshift)) < 0)
error("poke error %i", err);
trace(warn("...block %x done", block);)
total++;
}
return err;
}

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