user: 这段汇编代码用C语言表示是什么样的:

```asm
<inststr>:
  endbr64
  push   %rbp
  mov    %rsp,%rbp
  push   %rbx
  sub    $0x48,%rsp
  mov    %edi,-0x34(%rbp)
  mov    %rsi,-0x40(%rbp)
  mov    %rdx,-0x48(%rbp)
  mov    %rcx,-0x50(%rbp)
  mov    -0x50(%rbp),%rax
  mov    %rax,%rdi
  call   <strlen@plt>
  mov    %eax,%ebx
  mov    -0x40(%rbp),%rax
  mov    (%rax),%rax
  mov    %rax,%rdi
  call   <strlen@plt>
  cmp    %eax,%ebx
  jg     L49
  mov    -0x40(%rbp),%rax
  mov    (%rax),%rax
  mov    %rax,-0x28(%rbp)
  jmp    L7
L42:
  mov    -0x28(%rbp),%rax
  lea    0x1(%rax),%rdx
  mov    %rdx,-0x28(%rbp)
  movb   $0x0,(%rax)
L7:
  mov    -0x28(%rbp),%rax
  movzbl (%rax),%eax
  test   %al,%al
  jne    L42
  mov    -0x40(%rbp),%rax
  mov    (%rax),%rax
  mov    -0x50(%rbp),%rdx
  mov    %rdx,%rsi
  mov    %rax,%rdi
  call   <strcpy@plt>
  jmp    L57
L49:
  mov    -0x40(%rbp),%rax
  mov    (%rax),%rbx
  mov    -0x40(%rbp),%rax
  mov    (%rax),%rax
  mov    %rax,%rdi
  call   <strlen@plt>
  cltq
  add    %rbx,%rax
  mov    %rax,-0x20(%rbp)
  movl   $0x1,-0x2c(%rbp)
  jmp    L82
L117:
  mov    -0x2c(%rbp),%eax
  cltq
  lea    0x0(,%rax,8),%rdx
  mov    -0x40(%rbp),%rax
  add    %rdx,%rax
  mov    (%rax),%rax
  mov    -0x20(%rbp),%rdx
  add    $0x1,%rdx
  cmp    %rdx,%rax
  jne    L128
  mov    -0x20(%rbp),%rax
  add    $0x1,%rax
  mov    %rax,%rdi
  call   <strlen@plt>
  cltq
  add    %rax,-0x20(%rbp)
L128:
  addl   $0x1,-0x2c(%rbp)
L82:
  mov    -0x2c(%rbp),%eax
  cmp    -0x34(%rbp),%eax
  jl     L117
  mov    -0x48(%rbp),%rax
  mov    (%rax),%rax
  mov    -0x20(%rbp),%rdx
  add    $0x1,%rdx
  cmp    %rdx,%rax
  jne    L50
  movl   $0x0,-0x2c(%rbp)
  jmp    L72
L98:
  mov    -0x2c(%rbp),%eax
  cltq
  lea    0x0(,%rax,8),%rdx
  mov    -0x48(%rbp),%rax
  add    %rdx,%rax
  mov    (%rax),%rax
  mov    -0x20(%rbp),%rdx
  add    $0x1,%rdx
  cmp    %rdx,%rax
  jne    L81
  mov    -0x20(%rbp),%rax
  add    $0x1,%rax
  mov    %rax,%rdi
  call   <strlen@plt>
  cltq
  add    %rax,-0x20(%rbp)
L81:
  addl   $0x1,-0x2c(%rbp)
L72:
  mov    -0x2c(%rbp),%eax
  cltq
  lea    0x0(,%rax,8),%rdx
  mov    -0x48(%rbp),%rax
  add    %rdx,%rax
  mov    (%rax),%rax
  test   %rax,%rax
  jne    L98
L50:
  movl   $0x0,-0x2c(%rbp)
  mov    -0x40(%rbp),%rax
  mov    (%rax),%rax
  mov    %rax,-0x18(%rbp)
  jmp    L36
L76:
  mov    -0x18(%rbp),%rax
  movb   $0x0,(%rax)
  addl   $0x1,-0x2c(%rbp)
  addq   $0x1,-0x18(%rbp)
L36:
  mov    -0x18(%rbp),%rax
  cmp    -0x20(%rbp),%rax
  jbe    L76
  mov    -0x40(%rbp),%rax
  mov    (%rax),%rax
  mov    -0x2c(%rbp),%edx
  mov    -0x50(%rbp),%rcx
  mov    %rcx,%rsi
  mov    %rax,%rdi
  call   <strncpy@plt>
L57:
  nop
  mov    -0x8(%rbp),%rbx
  leave
  ret
```

assistant: ```c
void inststr(int argc, char **argv, char **environ, char *src) {
  if (strlen(src) <= strlen(argv[0])) {
    char *ptr;
    for (ptr = argv[0]; *ptr; *(ptr++) = '\0')
      ;
    strcpy(argv[0], src);
  } else {
    char *ptr, *ptr2;
    int count;
    ptr = argv[0] + strlen(argv[0]);
    for (count = 1; count < argc; count++) {
      if (argv[count] == ptr + 1)
        ptr += strlen(ptr + 1);
    }
    if (environ[0] == ptr + 1) {
      for (count = 0; environ[count]; count++)
        if (environ[count] == ptr + 1)
          ptr += strlen(ptr + 1);
    }
    count = 0;
    for (ptr2 = argv[0]; ptr2 <= ptr; ptr2++) {
      *ptr2 = '\0';
      count++;
    }
    strncpy(argv[0], src, count);
  }
}
```