user: 这段汇编代码用C语言表示是什么样的？

```asm
<safe_env>:
  endbr64
  push   %rbp
  mov    %rsp,%rbp
  push   %r15
  push   %r14
  push   %r13
  push   %r12
  push   %rbx
  sub    $0x58,%rsp
  mov    %rdi,-0x78(%rbp)
  mov    %fs:0x28,%rax
  mov    %rax,-0x38(%rbp)
  xor    %eax,%eax
  mov    %rsp,%rax
  mov    %rax,%rbx
  cmpq   $0x0,-0x78(%rbp)
  jne    L10
  mov    $0x0,%eax
  jmp    L68
L10:
  mov    -0x78(%rbp),%rax
  mov    %rax,%rdi
  call   <getenv@plt>
  mov    %rax,-0x68(%rbp)
  cmpq   $0x0,-0x68(%rbp)
  jne    L47
  mov    $0x0,%eax
  jmp    L68
L47:
  movl   $0x400,-0x6c(%rbp)
  mov    -0x6c(%rbp),%eax
  add    $0x1,%eax
  mov    %eax,%eax
  sub    $0x1,%rax
  mov    %rax,-0x60(%rbp)
  mov    -0x6c(%rbp),%eax
  add    $0x1,%eax
  mov    %eax,%eax
  mov    %rax,%r14
  mov    $0x0,%r15d
  mov    -0x6c(%rbp),%eax
  add    $0x1,%eax
  mov    %eax,%eax
  mov    %rax,%r12
  mov    $0x0,%r13d
  mov    -0x6c(%rbp),%eax
  add    $0x1,%eax
  mov    %eax,%edx
  mov    $0x10,%eax
  sub    $0x1,%rax
  add    %rdx,%rax
  mov    $0x10,%esi
  mov    $0x0,%edx
  div    %rsi
  imul   $0x10,%rax,%rax
  mov    %rax,%rcx
  and    $0xfffffffffffff000,%rcx
  mov    %rsp,%rdx
  sub    %rcx,%rdx
L8:
  cmp    %rdx,%rsp
  je     L4
  sub    $0x1000,%rsp
  orq    $0x0,0xff8(%rsp)
  jmp    L8
L4:
  mov    %rax,%rdx
  and    $0xfff,%edx
  sub    %rdx,%rsp
  mov    %rax,%rdx
  and    $0xfff,%edx
  test   %rdx,%rdx
  je     L14
  and    $0xfff,%eax
  sub    $0x8,%rax
  add    %rsp,%rax
  orq    $0x0,(%rax)
L14:
  mov    %rsp,%rax
  add    $0x0,%rax
  mov    %rax,-0x58(%rbp)
  mov    -0x6c(%rbp),%eax
  add    $0x1,%eax
  mov    %eax,%edx
  mov    -0x58(%rbp),%rax
  mov    $0x0,%esi
  mov    %rax,%rdi
  call   <memset@plt>
  mov    -0x58(%rbp),%rax
  mov    -0x6c(%rbp),%edx
  mov    -0x68(%rbp),%rcx
  mov    %rcx,%rsi
  mov    %rax,%rdi
  call   <strncpy@plt>
  mov    -0x58(%rbp),%rax
  mov    -0x6c(%rbp),%edx
  mov    %edx,%esi
  mov    %rax,%rdi
  call   <strnlen@plt>
  mov    %rax,-0x50(%rbp)
  mov    -0x6c(%rbp),%edx
  mov    -0x78(%rbp),%rax
  mov    %edx,%esi
  mov    %rax,%rdi
  call   <strnlen@plt>
  mov    %rax,-0x48(%rbp)
  mov    -0x48(%rbp),%rdx
  mov    -0x50(%rbp),%rax
  add    %rdx,%rax
  add    $0x2,%rax
  mov    $0x1,%esi
  mov    %rax,%rdi
  call   <calloc@plt>
  mov    %rax,-0x40(%rbp)
  mov    -0x48(%rbp),%rdx
  mov    -0x78(%rbp),%rcx
  mov    -0x40(%rbp),%rax
  mov    %rcx,%rsi
  mov    %rax,%rdi
  call   <strncat@plt>
  mov    -0x40(%rbp),%rax
  lea    D8(%rip),%rdx
  mov    %rdx,%rsi
  mov    %rax,%rdi
  call   <strcat@plt>
  mov    -0x50(%rbp),%rdx
  mov    -0x68(%rbp),%rcx
  mov    -0x40(%rbp),%rax
  mov    %rcx,%rsi
  mov    %rax,%rdi
  call   <strncat@plt>
  mov    -0x40(%rbp),%rax
L68:
  mov    %rbx,%rsp
  mov    -0x38(%rbp),%rdx
  sub    %fs:0x28,%rdx
  je     L45
  call   <__stack_chk_fail@plt>
L45:
  lea    -0x28(%rbp),%rsp
  pop    %rbx
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  pop    %rbp
  ret
```

tool_calls: name: unpack_data
arguments: tag: D8
data_type: string

tool: D8: =

assistant: ```c
char *safe_env(const char *name) {
  if (!name)
    return NULL;
  const char *env = getenv(name);
  if (!env)
    return NULL;
  const unsigned max_envlen = 1024;
  char newenv[max_envlen + 1];
  memset(&newenv[0], '\0', (sizeof((newenv)) / sizeof((newenv)[0])));
  strncpy(&newenv[0], env, max_envlen);
  size_t env_len = strnlen(&newenv[0], max_envlen);
  size_t nme_len = strnlen(name, max_envlen);
  char *ret = calloc(nme_len + env_len + 2, sizeof(char));
  strncat(ret, name, nme_len);
  strcat(ret, "=");
  strncat(ret, env, env_len);
  return ret;
}
```