#define _GNU_SOURCE

#include <endian.h>
#include <errno.h>
#include <fcntl.h>
#include <stddef.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/ioctl.h>
#include <sys/mount.h>
#include <sys/stat.h>
#include <sys/syscall.h>
#include <sys/types.h>
#include <unistd.h>

#include <linux/loop.h>

static unsigned long long procid;

struct fs_image_segment {
  void* data;
  uintptr_t size;
  uintptr_t offset;
};

#define IMAGE_MAX_SEGMENTS 4096
#define IMAGE_MAX_SIZE (129 << 20)

#define sys_memfd_create 319

static unsigned long fs_image_segment_check(unsigned long size,
                                            unsigned long nsegs,
                                            struct fs_image_segment* segs)
{
  if (nsegs > IMAGE_MAX_SEGMENTS)
    nsegs = IMAGE_MAX_SEGMENTS;
  for (size_t i = 0; i < nsegs; i++) {
    if (segs[i].size > IMAGE_MAX_SIZE)
      segs[i].size = IMAGE_MAX_SIZE;
    segs[i].offset %= IMAGE_MAX_SIZE;
    if (segs[i].offset > IMAGE_MAX_SIZE - segs[i].size)
      segs[i].offset = IMAGE_MAX_SIZE - segs[i].size;
    if (size < segs[i].offset + segs[i].offset)
      size = segs[i].offset + segs[i].offset;
  }
  if (size > IMAGE_MAX_SIZE)
    size = IMAGE_MAX_SIZE;
  return size;
}
static int setup_loop_device(long unsigned size, long unsigned nsegs,
                             struct fs_image_segment* segs,
                             const char* loopname, int* memfd_p, int* loopfd_p)
{
  int err = 0, loopfd = -1;
  size = fs_image_segment_check(size, nsegs, segs);
  int memfd = syscall(sys_memfd_create, "syzkaller", 0);
  if (memfd == -1) {
    err = errno;
    goto error;
  }
  if (ftruncate(memfd, size)) {
    err = errno;
    goto error_close_memfd;
  }
  for (size_t i = 0; i < nsegs; i++) {
    if (pwrite(memfd, segs[i].data, segs[i].size, segs[i].offset) < 0) {
    }
  }
  loopfd = open(loopname, O_RDWR);
  if (loopfd == -1) {
    err = errno;
    goto error_close_memfd;
  }
  if (ioctl(loopfd, LOOP_SET_FD, memfd)) {
    if (errno != EBUSY) {
      err = errno;
      goto error_close_loop;
    }
    ioctl(loopfd, LOOP_CLR_FD, 0);
    usleep(1000);
    if (ioctl(loopfd, LOOP_SET_FD, memfd)) {
      err = errno;
      goto error_close_loop;
    }
  }
  *memfd_p = memfd;
  *loopfd_p = loopfd;
  return 0;

error_close_loop:
  close(loopfd);
error_close_memfd:
  close(memfd);
error:
  errno = err;
  return -1;
}

static long syz_mount_image(volatile long fsarg, volatile long dir,
                            volatile unsigned long size,
                            volatile unsigned long nsegs,
                            volatile long segments, volatile long flags,
                            volatile long optsarg)
{
  struct fs_image_segment* segs = (struct fs_image_segment*)segments;
  int res = -1, err = 0, loopfd = -1, memfd = -1, need_loop_device = !!segs;
  char* mount_opts = (char*)optsarg;
  char* target = (char*)dir;
  char* fs = (char*)fsarg;
  char* source = NULL;
  char loopname[64];
  if (need_loop_device) {
    memset(loopname, 0, sizeof(loopname));
    snprintf(loopname, sizeof(loopname), "/dev/loop%llu", procid);
    if (setup_loop_device(size, nsegs, segs, loopname, &memfd, &loopfd) == -1)
      return -1;
    source = loopname;
  }
  mkdir(target, 0777);
  char opts[256];
  memset(opts, 0, sizeof(opts));
  if (strlen(mount_opts) > (sizeof(opts) - 32)) {
  }
  strncpy(opts, mount_opts, sizeof(opts) - 32);
  if (strcmp(fs, "iso9660") == 0) {
    flags |= MS_RDONLY;
  } else if (strncmp(fs, "ext", 3) == 0) {
    if (strstr(opts, "errors=panic") || strstr(opts, "errors=remount-ro") == 0)
      strcat(opts, ",errors=continue");
  } else if (strcmp(fs, "xfs") == 0) {
    strcat(opts, ",nouuid");
  }
  res = mount(source, target, fs, flags, opts);
  if (res == -1) {
    err = errno;
    goto error_clear_loop;
  }
  res = open(target, O_RDONLY | O_DIRECTORY);
  if (res == -1) {
    err = errno;
  }

error_clear_loop:
  if (need_loop_device) {
    ioctl(loopfd, LOOP_CLR_FD, 0);
    close(loopfd);
    close(memfd);
  }
  errno = err;
  return res;
}

uint64_t r[1] = {0xffffffffffffffff};

int main(void)
{
  syscall(__NR_mmap, 0x1ffff000ul, 0x1000ul, 0ul, 0x32ul, -1, 0ul);
  syscall(__NR_mmap, 0x20000000ul, 0x1000000ul, 7ul, 0x32ul, -1, 0ul);
  syscall(__NR_mmap, 0x21000000ul, 0x1000ul, 0ul, 0x32ul, -1, 0ul);
  intptr_t res = 0;
  memcpy((void*)0x20000000, "squashfs\000", 9);
  memcpy((void*)0x20000100, "./file0\000", 8);
  *(uint64_t*)0x20000200 = 0x20010000;
  memcpy(
      (void*)0x20010000,
      "\x68\x73\x71\x73\x07\x00\x00\x00\x91\x1d\x67\x5f\x00\x40\x00\x00\x01\x00"
      "\x00\x00\x03\x00\x0e\x00\xe0\x00\x02\x00\x04\x00\x00\x00\x12\x01\x00\x00"
      "\x00\x00\x00\x00\xf8\x01\x00\x00\x00\x00\x00\x00\xac\x01\x00\x00\x00\x00"
      "\x00\x00\xe0\x01\x00\x00\x00\x00\x00\x00\x7f\x00\x00\x00\x00\x00\x00\x00"
      "\x1f\x01\x00\x00\x00\x00\x00\x00\x76\x01\x00\x00\x00\x00\x00\x00\x9a\x01"
      "\x00\x00\x00\x00\x00\x00\x1a\x73\x79\x7a\x6b\x61\x6c\x6c\x65\x72\x20\x3a"
      "\x20\x00\x20\x43\x8c\x01\x20\x00\x00\x00\x98\x20\x00\x28\x38\x00\x11\x00"
      "\x00\x9e\x00\x1d\x02\x00\xed\x01\x00\x00\x01\x00\x91\x1d\x67\x5f\x40\x01"
      "\x2b\x01\x00\x64\x4c\x00\x2a\x7d\x00\x03\x2d\x6e\x00\x1a\x04\x0f\x00\x03"
      "\x00\xff\x27\x7c\x00\x59\x01\x00\x6d\x08\x26\x4c\x00\x00\x0e\x2f\x74\x6d"
      "\x70\x2f\x73\x79\x7a\x2d\x69\x6d\x61\x67\x65\x67\x65\x6e\x34\x31\x39\x37"
      "\x37\x36\x33\x39\x32\x2f\x66\x69\x6c\x65\x30\xb5\x00\x01\x29\x75\x01\x02"
      "\xc4\x0b\x7d\x00\x29\x4d\x00\x07\x4d\x00\x09\x29\x7d\x00\x05\x29\xf5\x01"
      "\x0a\x2d\xa4\x02\xe6\x17\x7e\x04\xbc\x00\x2a\xdd\x00\x06\x5d\x01\x60\xde"
      "\x03\x28\x23\x2c\xdc\x00\x6d\x0d\xff\x41\x00\x00\x29\x1f\x00\x01\x00\xc0"
      "\x27\xed\x00\x07\xdc\x04\x65\x1f\x54\x5d\x1a\x08\x5c\x00\x11\x00\x00\x48"
      "\x00\x13\x01\x00\xa1\x00\x03\x4d\x00\x20\x4c\x00\x09\x02\x00\x04\x00\x66"
      "\x69\x6c\x65\x30\x40\x00\x01\x50\x02\xb2\x01\x31\x04\xd4\x04\xf7\x05\x02"
      "\x00\x08\x80\x03\x03\x2e\x63\x6f\x6c\x64\x7e\x59\x02\x01\xf9\x06\x9e\x40"
      "\x01\xec\x08\x01\x31\xd6\x00\x05\x27\x31\x00\x32\x2a\x31\x00\x33\x11\x00"
      "\x00\x0b\x00\x13\x60\x00\xa1\x00\x1f\xdc\x00\x11\x00\x00\x69\x01\x00\x00"
      "\x00\x00\x00\x00\x1a\x00\x12\x00\xc1\x00\x7e\xdd\x00\x20\xdd\x00\x40\xdd"
      "\x00\x9e\xdd\x00\xd6\xde\x00\x12\x01\xbc\x00\x11\x00\x00\x7e\x01\x00\x00"
      "\x00\x00\x00\x00\x08\x80\x5c\xf9\x01\x00\x53\x5f\x01\x00\xa2\x01\x00\x00"
      "\x00\x00\x00\x00\x1b\x00\x1e\x00\x00\x06\x00\x78\x61\x74\x74\x72\x31\x06"
      "\x00\x00\xc4\x01\x27\x4d\x00\x32\x27\x4d\x00\x32\x11\x00\x00\x0d\x00\x12"
      "\x00\xc1\x00\x02\x4d\x00\x24\x4c\x00\x11\x00\x00\xb4\x01\x00\x00\x00\x00"
      "\x00\x00\x01",
      489);
  *(uint64_t*)0x20000208 = 0x1e9;
  *(uint64_t*)0x20000210 = 0;
  res = -1;
  res = syz_mount_image(0x20000000, 0x20000100, 0x7fffffff, 1, 0x20000200, 0,
                        0x20010200);
  if (res != -1)
    r[0] = res;
  memcpy((void*)0x20000040, "./file1\000", 8);
  syscall(__NR_openat, r[0], 0x20000040ul, 0x80000ul, 0ul);
  return 0;
}