/*
  Copyright (c) 2008-2013 Red Hat, Inc. <http://www.redhat.com>
  This file is part of GlusterFS.

  This file is licensed to you under your choice of the GNU Lesser
  General Public License, version 3 or any later version (LGPLv3 or
  later), or the GNU General Public License, version 2 (GPLv2), in all
  cases as published by the Free Software Foundation.
*/

#include <stdlib.h>
#include <stdio.h>
#include <sys/types.h>
#include <string.h>
#include <sys/stat.h>
#include <sys/syscall.h>
#include <unistd.h>
#include <fcntl.h>

#define MAX_NUM_OPS (1 << 20)
#define MAX_FILE_SIZE (1 << 30)

typedef enum { READ_OP, WRITE_OP, TRUNC_OP, LAST_OP } frag_op;

struct frag_ctx {
    int test_fd;
    int good_fd;
    char *test_buf;
    char *good_buf;
    char *content;
    int max_file_size;
};

typedef int (*frag_op_t)(struct frag_ctx *ctx, off_t offset, size_t count);

static int
doread(int fd, off_t offset, size_t count, char *buf, int max_file_size)
{
    int ret = 0;
    int was_read = 0;

    if (lseek(fd, offset, SEEK_SET) == -1) {
        perror("lseek failed");
        return -1;
    }
    while (count) {
        ret = read(fd, buf + offset + was_read, count);
        if (ret < 0)
            return -1;
        if (ret == 0)
            break;
        if (ret > count) {
            fprintf(stderr, "READ: read more than asked\n");
            return -1;
        }
        count -= ret;
        was_read += ret;
    }
    return ret;
}

static int
dowrite(int fd, off_t offset, size_t count, char *buf)
{
    int ret;

    ret = lseek(fd, offset, SEEK_SET);
    if (ret == -1)
        return ret;
    return write(fd, buf, count);
}

static int
dotrunc(int fd, off_t offset)
{
    int ret;

    ret = ftruncate(fd, offset);
    if (ret == -1)
        perror("truncate failed");
    return ret;
}

static int
prepare_file(char *filename, int *fd, char **buf, int max_file_size)
{
    int ret;

    *buf = malloc(max_file_size);
    if (*buf == NULL) {
        perror("malloc failed");
        return -1;
    }
    *fd = open(filename, O_CREAT | O_RDWR, S_IRWXU);
    if (*fd == -1) {
        perror("open failed");
        free(*buf);
        *buf = NULL;
        return -1;
    }
    return 0;
}

/*
 * @offset, @count: random values from [0, max_file_size - 1]
 */
static int
frag_write(struct frag_ctx *ctx, off_t offset, size_t count)
{
    int ret;
    struct stat test_stbuf;
    struct stat good_stbuf;

    if (offset + count > ctx->max_file_size)
        offset = offset / 2;
    if (offset + count > ctx->max_file_size)
        count = count / 2;

    if (fstat(ctx->test_fd, &test_stbuf)) {
        fprintf(stderr, "WRITE: fstat of test file failed\n");
        return -1;
    }
    if (offset > test_stbuf.st_size)
        printf("writing hole\n");

    ret = dowrite(ctx->test_fd, offset, count, ctx->content);
    if (ret < 0 || ret != count) {
        fprintf(stderr, "WRITE: failed to write test file\n");
        return -1;
    }
    ret = dowrite(ctx->good_fd, offset, count, ctx->content);
    if (ret < 0 || ret != count) {
        fprintf(stderr, "WRITE: failed to write test file\n");
        return -1;
    }
    if (fstat(ctx->test_fd, &test_stbuf)) {
        fprintf(stderr, "WRITE: fstat of test file failed\n");
        return -1;
    }
    if (fstat(ctx->good_fd, &good_stbuf)) {
        fprintf(stderr, "WRITE: fstat of good file failed\n");
        return -1;
    }
    if (test_stbuf.st_size != good_stbuf.st_size) {
        fprintf(stderr, "READ: Bad file size %d (expected %d)\n",
                (int)test_stbuf.st_size, (int)good_stbuf.st_size);
        return -1;
    }
    return 0;
}

/*
 * @offset, @count: random values from [0, max_file_size - 1]
 */
static int
frag_read(struct frag_ctx *ctx, off_t offset, size_t count)
{
    ssize_t test_ret;
    ssize_t good_ret;

    test_ret = doread(ctx->test_fd, offset, count, ctx->test_buf,
                      ctx->max_file_size);
    if (test_ret < 0) {
        fprintf(stderr, "READ: failed to read test file\n");
        return -1;
    }
    good_ret = doread(ctx->good_fd, offset, count, ctx->good_buf,
                      ctx->max_file_size);
    if (good_ret < 0) {
        fprintf(stderr, "READ: failed to read good file\n");
        return -1;
    }
    if (test_ret != good_ret) {
        fprintf(stderr, "READ: Bad return value %d (expected %d\n)", test_ret,
                good_ret);
        return -1;
    }
    if (memcmp(ctx->test_buf + offset, ctx->good_buf + offset, good_ret)) {
        fprintf(stderr, "READ: bad data\n");
        return -1;
    }
    return 0;
}

/*
 * @offset: random value from [0, max_file_size - 1]
 */
static int
frag_truncate(struct frag_ctx *ctx, off_t offset,
              __attribute__((unused)) size_t count)
{
    int ret;
    struct stat test_stbuf;
    struct stat good_stbuf;

    if (fstat(ctx->test_fd, &test_stbuf)) {
        fprintf(stderr, "TRUNCATE: fstat of test file failed\n");
        return -1;
    }
    if (offset > test_stbuf.st_size)
        printf("expanding truncate to %d\n", offset);
    else if (offset < test_stbuf.st_size)
        printf("shrinking truncate to %d\n", offset);
    else
        printf("trivial truncate\n");

    ret = dotrunc(ctx->test_fd, offset);
    if (ret == -1) {
        fprintf(stderr, "TRUNCATE: failed for test file\n");
        return -1;
    }
    ret = dotrunc(ctx->good_fd, offset);
    if (ret == -1) {
        fprintf(stderr, "TRUNCATE: failed for good file\n");
        return -1;
    }
    if (fstat(ctx->test_fd, &test_stbuf)) {
        fprintf(stderr, "TRUNCATE: fstat of test file failed\n");
        return -1;
    }
    if (fstat(ctx->good_fd, &good_stbuf)) {
        fprintf(stderr, "TRUNCATE: fstat of good file failed\n");
        return -1;
    }
    if (test_stbuf.st_size != good_stbuf.st_size) {
        fprintf(stderr, "TRUNCATE: bad test file size %d (expected %d)\n",
                test_stbuf.st_size, good_stbuf.st_size);
        return -1;
    }
    return 0;
}

frag_op_t frag_ops[LAST_OP] = {[READ_OP] = frag_read,
                               [WRITE_OP] = frag_write,
                               [TRUNC_OP] = frag_truncate};

static void
put_ctx(struct frag_ctx *ctx)
{
    if (ctx->test_buf)
        free(ctx->test_buf);
    if (ctx->good_buf)
        free(ctx->good_buf);
    if (ctx->content)
        free(ctx->content);
}

main(int argc, char *argv[])
{
    int i;
    int ret = 0;
    struct frag_ctx ctx;
    char *test_filename = NULL;
    char *good_filename = NULL;
    int num_ops;
    int max_file_size;

    memset(&ctx, 0, sizeof(ctx));
    if (argc != 5) {
        fprintf(stderr,
                "usage: %s <test-file-name> <good-file-name> <max-file-size> "
                "<number-of-operations>\n",
                argv[0]);
        ret = -1;
        goto exit;
    }
    test_filename = argv[1];
    good_filename = argv[2];
    max_file_size = atoi(argv[3]);
    if (max_file_size > MAX_FILE_SIZE)
        max_file_size = MAX_FILE_SIZE;
    num_ops = atoi(argv[4]);
    if (num_ops > MAX_NUM_OPS)
        num_ops = MAX_NUM_OPS;

    ret = prepare_file(test_filename, &ctx.test_fd, &ctx.test_buf,
                       max_file_size);
    if (ret)
        goto exit;
    ret = prepare_file(good_filename, &ctx.good_fd, &ctx.good_buf,
                       max_file_size);
    if (ret) {
        if (close(ctx.test_fd) == -1)
            perror("close test_buf failed");
        goto exit;
    }
    ctx.content = malloc(max_file_size);
    if (!ctx.content) {
        perror("malloc failed");
        goto close;
    }
    ctx.max_file_size = max_file_size;
    for (i = 0; i < max_file_size; i++)
        ctx.content[i] = random() % 256;

    for (i = 0; i < num_ops; i++) {
        ret = frag_ops[random() % LAST_OP](
            &ctx, random() % max_file_size, /* offset */
            random() % max_file_size /* count */);
        if (ret)
            break;
    }
close:
    if (close(ctx.test_fd) == -1)
        perror("close test_fd failed");
    if (close(ctx.good_fd) == -1)
        perror("close good_fd failed");
exit:
    put_ctx(&ctx);
    if (ret)
        exit(1);
    exit(0);
}

/*
  Local variables:
  c-indentation-style: "K&R"
  mode-name: "LC"
  c-basic-offset: 8
  tab-width: 8
  fill-column: 80
  scroll-step: 1
  End:
*/