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// SPDX-License-Identifier: GPL-2.0+
/*
* Copyright (c) 2021 RedHat Inc. All Rights Reserved.
*
* mmap a file, alloc blocks, reading&writing blocks with overlapping. For example:
*
* |<--- block --->|<--- block --->|
* len len
* +---------------+---------------+
* |AAAA| ........ |AAAA| ........ |
* +---------------+---------------+
* | |
* | `------------+
* `-----------------------+ |
* | |
* V V
* +---------------+---------------+----+
* |AAAA| ........ |AAAA| ... |AAAA|AAAA|
* +---------------+---------------+----+
*/
#include <sys/types.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <sys/mman.h>
#include <string.h>
#include <sys/uio.h>
#include <unistd.h>
void usage(char *progname)
{
fprintf(stderr, "usage: %s [-b blocksize ] [-c count] [-l length] filename\n"
"\tmmap $count * $blocksize bytes memory, pwritev $length bytes in each block. blocksize=4096, count=2, length=12 by default.\n"
"e.g: %s -b 4096 -c 2 -l 12 filename\n",
progname, progname);
exit(1);
}
int main(int argc, char **argv)
{
char *filename = NULL;
size_t bsize = 4096;
size_t count = 2;
size_t length = 12;
int fd, i, c;
void *base;
char *buf, *cmp_buf;
struct iovec *iov;
int ret = 0;
while ((c = getopt(argc, argv, "b:l:c:")) != -1) {
char *endp;
switch (c) {
case 'b':
bsize = strtoul(optarg, &endp, 0);
break;
case 'c':
count = strtoul(optarg, &endp, 0);
break;
case 'l':
length = strtoul(optarg, &endp, 0);
break;
default:
usage(argv[0]);
}
}
if (optind == argc - 1)
filename = argv[optind];
else
usage(argv[0]);
if (length >= bsize) {
printf("-l length must be less than -b blocksize\n");
usage(argv[0]);
}
fd = open(filename, O_RDWR);
if (fd == -1) {
fprintf(stderr, "open %s failed:%s\n", filename, strerror(errno));
exit(1);
}
base = mmap(NULL, bsize * count, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);
if (base == MAP_FAILED) {
fprintf(stderr, "mmap failed %s\n", strerror(errno));
exit(1);
}
/* Write each of blocks */
buf = malloc(length);
memset(buf, 0xAA, length);
for (i=0; i<count; i++) {
ret = pwrite(fd, buf, length, i * bsize);
if (ret == -1) {
fprintf(stderr, "pwrite failed %s\n", strerror(errno));
exit(1);
}
}
/* Copy from the beginning of each blocks ... */
iov = malloc(sizeof(struct iovec) * count);
for (i=0; i<count; i++) {
iov[i].iov_base = base + i * bsize;
iov[i].iov_len = length;
}
/* ... Write to the last block with offset ($bsize - $length) */
ret = pwritev(fd, iov, count, bsize * count - length);
if (ret == -1) {
fprintf(stderr, "pwritev failed %s\n", strerror(errno));
exit(1);
}
/* Verify data */
cmp_buf = malloc(length);
for (i=0; i<count; i++) {
ret = pread(fd, cmp_buf, length, bsize * count + (i - 1) * length);
if (ret == -1) {
fprintf(stderr, "pread failed %s\n", strerror(errno));
exit(1);
}
if (memcmp(buf, cmp_buf, length))
printf("Find corruption\n");
}
munmap(base, bsize * count);
free(buf);
free(cmp_buf);
free(iov);
close(fd);
return 0;
}
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