user: Demonstrate the C code that generates the assembly output below:

```asm
<file_path_from_stack>:
  endbr64
  push   %rbp
  mov    %rsp,%rbp
  sub    $0x60,%rsp
  mov    %rdi,-0x58(%rbp)
  mov    %rsi,-0x60(%rbp)
  mov    %fs:0x28,%rax
  mov    %rax,-0x8(%rbp)
  xor    %eax,%eax
  cmpq   $0x0,-0x60(%rbp)
  setne  %al
  movzbl %al,%eax
  mov    %eax,%edi
  call   <assert@plt>
  mov    -0x60(%rbp),%rax
  mov    %rax,%rdi
  call   <strlen@plt>
  mov    %rax,-0x30(%rbp)
  movq   $0x0,-0x48(%rbp)
  movq   $0x0,-0x40(%rbp)
  jmp    L75
L50:
  lea    -0x48(%rbp),%rdx
  mov    -0x58(%rbp),%rax
  mov    %rdx,%rsi
  mov    %rax,%rdi
  call   <stack_move@plt>
  mov    %rax,-0x10(%rbp)
  cmpq   $0x0,-0x10(%rbp)
  setne  %al
  movzbl %al,%eax
  mov    %eax,%edi
  call   <assert@plt>
  mov    -0x10(%rbp),%rax
  mov    %rax,%rdi
  call   <strlen@plt>
  mov    -0x40(%rbp),%rdx
  add    %rdx,%rax
  add    $0x1,%rax
  mov    %rax,-0x40(%rbp)
L75:
  mov    -0x58(%rbp),%rax
  mov    %rax,%rdi
  call   <stack_empty@plt>
  test   %eax,%eax
  je     L50
  mov    -0x40(%rbp),%rdx
  mov    -0x30(%rbp),%rax
  add    %rdx,%rax
  add    $0x1,%rax
  mov    %rax,%rdi
  call   <malloc@plt>
  mov    %rax,-0x28(%rbp)
  cmpq   $0x0,-0x28(%rbp)
  jne    L25
  jmp    L65
L9:
  mov    -0x58(%rbp),%rdx
  lea    -0x48(%rbp),%rax
  mov    %rdx,%rsi
  mov    %rax,%rdi
  call   <stack_move@plt>
L65:
  lea    -0x48(%rbp),%rax
  mov    %rax,%rdi
  call   <stack_empty@plt>
  test   %eax,%eax
  je     L9
  mov    $0x0,%eax
  jmp    L62
L25:
  mov    -0x28(%rbp),%rax
  mov    %rax,-0x38(%rbp)
  jmp    L77
L21:
  mov    -0x58(%rbp),%rdx
  lea    -0x48(%rbp),%rax
  mov    %rdx,%rsi
  mov    %rax,%rdi
  call   <stack_move@plt>
  mov    %rax,-0x20(%rbp)
  mov    -0x20(%rbp),%rax
  mov    %rax,%rdi
  call   <strlen@plt>
  mov    %rax,-0x18(%rbp)
  mov    -0x18(%rbp),%rdx
  mov    -0x20(%rbp),%rcx
  mov    -0x38(%rbp),%rax
  mov    %rcx,%rsi
  mov    %rax,%rdi
  call   <memcpy@plt>
  mov    -0x38(%rbp),%rdx
  mov    -0x18(%rbp),%rax
  add    %rdx,%rax
  movb   $0x2f,(%rax)
  mov    -0x18(%rbp),%rax
  add    $0x1,%rax
  add    %rax,-0x38(%rbp)
L77:
  lea    -0x48(%rbp),%rax
  mov    %rax,%rdi
  call   <stack_empty@plt>
  test   %eax,%eax
  je     L21
  mov    -0x38(%rbp),%rax
  sub    -0x28(%rbp),%rax
  mov    %rax,%rdx
  mov    -0x40(%rbp),%rax
  cmp    %rax,%rdx
  sete   %al
  movzbl %al,%eax
  mov    %eax,%edi
  call   <assert@plt>
  cmpq   $0x0,-0x30(%rbp)
  je     L69
  mov    -0x30(%rbp),%rdx
  mov    -0x60(%rbp),%rcx
  mov    -0x38(%rbp),%rax
  mov    %rcx,%rsi
  mov    %rax,%rdi
  call   <memcpy@plt>
  mov    -0x38(%rbp),%rdx
  mov    -0x30(%rbp),%rax
  add    %rdx,%rax
  movb   $0x0,(%rax)
  jmp    L40
L69:
  mov    -0x40(%rbp),%rax
  lea    -0x1(%rax),%rdx
  mov    -0x28(%rbp),%rax
  add    %rdx,%rax
  movb   $0x0,(%rax)
L40:
  mov    -0x28(%rbp),%rax
L62:
  mov    -0x8(%rbp),%rdx
  sub    %fs:0x28,%rdx
  je     L20
  call   <__stack_chk_fail@plt>
L20:
  leave
  ret
```

assistant: ```c
const char *file_path_from_stack(struct stack **path, const char *fname) {
  assert(fname != NULL);
  const size_t fnamelen = strlen(fname);
  struct stack *tmp = NULL;
  size_t plen = 0;
  while (!stack_empty(path)) {
    const void *frag = stack_move(path, &tmp);
    assert(frag != NULL);
    plen += strlen((const char *)frag) + 1;
  }
  char *full = malloc(plen + fnamelen + 1);
  if (full == NULL) {
    while (!stack_empty(&tmp))
      stack_move(&tmp, path);
    return NULL;
  }
  char *p = full;
  while (!stack_empty(&tmp)) {
    const void *frag = stack_move(&tmp, path);
    const size_t flen = strlen((const char *)frag);
    memcpy(p, frag, flen);
    p[flen] = '/';
    p += flen + 1;
  }
  assert((size_t)(p - full) == plen);
  if (fnamelen > 0) {
    memcpy(p, fname, fnamelen);
    p[fnamelen] = '\0';
  } else {
    full[plen - 1] = '\0';
  }
  return full;
}
```