user: What is the c source code of the assembly code below:

```asm
<main>:
  endbr64
  push   %r15
  lea    D18(%rip),%rdi
  push   %r14
  push   %r13
  push   %r12
  push   %rbp
  push   %rbx
  lea    D21(%rip),%rbx
  sub    $0x28,%rsp
  mov    %fs:0x28,%rax
  mov    %rax,0x18(%rsp)
  xor    %eax,%eax
  mov    %rsp,%rbp
  call   <puts@plt>
  mov    %rbp,%rsi
  mov    %rbx,%rdi
  call   <stat@plt>
  cmp    $0xffffffff,%eax
  je     L8
L76:
  mov    0x8(%rsp),%esi
  lea    D118(%rip),%r15
  xor    %eax,%eax
  lea    D59(%rip),%r14
  mov    %r15,%rdi
  lea    D12(%rip),%r12
  call   <printf@plt>
  mov    (%rsp),%esi
  mov    %r14,%rdi
  xor    %eax,%eax
  call   <printf@plt>
  mov    %rbp,%rsi
  mov    %r12,%rdi
  call   <lstat@plt>
  cmp    $0xffffffff,%eax
  je     L14
L19:
  mov    0x8(%rsp),%esi
  lea    D120(%rip),%r13
  xor    %eax,%eax
  mov    %r13,%rdi
  call   <printf@plt>
  mov    (%rsp),%esi
  lea    D138(%rip),%rdi
  xor    %eax,%eax
  call   <printf@plt>
  xor    %esi,%esi
  mov    $0xffffffff,%edx
  mov    %r12,%rdi
  call   <lchown@plt>
  cmp    $0xffffffff,%eax
  je     L37
L42:
  lea    D76(%rip),%rdi
  call   <puts@plt>
  mov    %rbp,%rsi
  mov    %rbx,%rdi
  call   <stat@plt>
  cmp    $0xffffffff,%eax
  je     L91
L55:
  mov    0x8(%rsp),%esi
  mov    %r15,%rdi
  xor    %eax,%eax
  call   <printf@plt>
  mov    (%rsp),%esi
  mov    %r14,%rdi
  xor    %eax,%eax
  call   <printf@plt>
  mov    %rbp,%rsi
  mov    %r12,%rdi
  call   <lstat@plt>
  cmp    $0xffffffff,%eax
  je     L20
L29:
  mov    0x8(%rsp),%esi
  mov    %r13,%rdi
  xor    %eax,%eax
  call   <printf@plt>
  mov    (%rsp),%esi
  xor    %eax,%eax
  lea    D138(%rip),%rdi
  call   <printf@plt>
  mov    0x18(%rsp),%rax
  sub    %fs:0x28,%rax
  jne    L6
  add    $0x28,%rsp
  xor    %eax,%eax
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
L8:
  lea    D90(%rip),%rdi
  call   <perror@plt>
  mov    $0x1,%edi
  call   <exit@plt>
  jmp    L76
L20:
  lea    D90(%rip),%rdi
  call   <perror@plt>
  mov    $0x1,%edi
  call   <exit@plt>
  jmp    L29
L91:
  lea    D90(%rip),%rdi
  call   <perror@plt>
  mov    $0x1,%edi
  call   <exit@plt>
  jmp    L55
L37:
  lea    D79(%rip),%rdi
  call   <perror@plt>
  mov    $0x1,%edi
  call   <exit@plt>
  jmp    L42
L14:
  lea    D90(%rip),%rdi
  call   <perror@plt>
  mov    $0x1,%edi
  call   <exit@plt>
  jmp    L19
L6:
  call   <__stack_chk_fail@plt>
```

tool_calls: name: disassemble_data
arguments: data_label: D18
data_type: string
name: disassemble_data
arguments: data_label: D21
data_type: string
name: disassemble_data
arguments: data_label: D118
data_type: string
name: disassemble_data
arguments: data_label: D59
data_type: string
name: disassemble_data
arguments: data_label: D12
data_type: string
name: disassemble_data
arguments: data_label: D120
data_type: string
name: disassemble_data
arguments: data_label: D138
data_type: string
name: disassemble_data
arguments: data_label: D76
data_type: string
name: disassemble_data
arguments: data_label: D90
data_type: string
name: disassemble_data
arguments: data_label: D79
data_type: string

tool: D18: before changing

tool: D21: test.txt

tool: D118: the owner of test.txt is : %u


tool: D59: the group of test.txt is : %u


tool: D12: sl

tool: D120: the owner of sl is : %u


tool: D138: the group of sl is : %u


tool: D76: after changing

tool: D90: fail to get status

tool: D79: fail to change owner

assistant: ```c
int main(void) {
  struct stat statbuf;
  printf("before changing\n");
  if (stat("test.txt", &statbuf) == -1) {
    perror("fail to get status");
    exit(1);
  }
  printf("the owner of test.txt is : %u\n", (unsigned int)statbuf.st_uid);
  printf("the group of test.txt is : %u\n", (unsigned int)statbuf.st_gid);
  if (lstat("sl", &statbuf) == -1) {
    perror("fail to get status");
    exit(1);
  }
  printf("the owner of sl is : %u\n", (unsigned int)statbuf.st_uid);
  printf("the group of sl is : %u\n", (unsigned int)statbuf.st_gid);
  if (lchown("sl", 0, -1) == -1) {
    perror("fail to change owner");
    exit(1);
  }
  printf("after changing\n");
  if (stat("test.txt", &statbuf) == -1) {
    perror("fail to get status");
    exit(1);
  }
  printf("the owner of test.txt is : %u\n", (unsigned int)statbuf.st_uid);
  printf("the group of test.txt is : %u\n", (unsigned int)statbuf.st_gid);
  if (lstat("sl", &statbuf) == -1) {
    perror("fail to get status");
    exit(1);
  }
  printf("the owner of sl is : %u\n", (unsigned int)statbuf.st_uid);
  printf("the group of sl is : %u\n", (unsigned int)statbuf.st_gid);
  return 0;
}
```