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

```asm
<test_strncat_range>:
  endbr64
  push   %r12
  xor    %edi,%edi
  push   %rbp
  sub    $0x28,%rsp
  mov    %fs:0x28,%rax
  mov    %rax,0x18(%rsp)
  xor    %eax,%eax
  lea    0xe(%rsp),%rbp
  movl   $0x0,0xe(%rsp)
  lea    0x13(%rsp),%r12
  movb   $0x0,0x12(%rsp)
  call   <string_range@plt>
  xor    %edx,%edx
  mov    %rbp,%rdi
  mov    %eax,%esi
  call   <strncat@plt>
  mov    %rbp,%rdi
  call   <sink@plt>
  xor    %edi,%edi
  call   <string_range@plt>
  mov    $0x1,%edx
  mov    %rbp,%rdi
  mov    %eax,%esi
  call   <strncat@plt>
  mov    %rbp,%rdi
  call   <sink@plt>
  xor    %edi,%edi
  call   <string_range@plt>
  mov    $0x2,%edx
  mov    %rbp,%rdi
  mov    %eax,%esi
  call   <strncat@plt>
  mov    %rbp,%rdi
  call   <sink@plt>
  xor    %edi,%edi
  call   <string_range@plt>
  mov    $0x3,%edx
  mov    %rbp,%rdi
  mov    %eax,%esi
  call   <strncat@plt>
  mov    %rbp,%rdi
  call   <sink@plt>
  xor    %edi,%edi
  call   <string_range@plt>
  mov    $0x4,%edx
  mov    %rbp,%rdi
  mov    %eax,%esi
  call   <strncat@plt>
  mov    %rbp,%rdi
  call   <sink@plt>
  xor    %edi,%edi
  call   <string_range@plt>
  xor    %edx,%edx
  mov    %r12,%rdi
  mov    %eax,%esi
  call   <strncat@plt>
  mov    %r12,%rdi
  call   <sink@plt>
  xor    %edi,%edi
  call   <string_range@plt>
  mov    $0x1,%edx
  mov    %r12,%rdi
  mov    %eax,%esi
  call   <strncat@plt>
  mov    %r12,%rdi
  call   <sink@plt>
  mov    $0x1,%edi
  call   <string_range@plt>
  mov    $0x1,%edx
  mov    %r12,%rdi
  mov    %eax,%esi
  call   <strncat@plt>
  mov    %r12,%rdi
  call   <sink@plt>
  xor    %edi,%edi
  call   <string_range@plt>
  mov    $0x5,%edx
  mov    %rbp,%rdi
  mov    %eax,%esi
  call   <strncat@plt>
  mov    %rbp,%rdi
  call   <sink@plt>
  xor    %edi,%edi
  call   <string_range@plt>
  mov    $0x6,%edx
  mov    %rbp,%rdi
  mov    %eax,%esi
  call   <strncat@plt>
  mov    %rbp,%rdi
  call   <sink@plt>
  mov    $0x1,%edi
  call   <string_range@plt>
  xor    %edx,%edx
  mov    %rbp,%rdi
  mov    %eax,%esi
  call   <strncat@plt>
  mov    %rbp,%rdi
  call   <sink@plt>
  mov    $0x1,%edi
  call   <string_range@plt>
  mov    $0x1,%edx
  mov    %rbp,%rdi
  mov    %eax,%esi
  call   <strncat@plt>
  mov    %rbp,%rdi
  call   <sink@plt>
  mov    $0x1,%edi
  call   <string_range@plt>
  mov    $0x2,%edx
  mov    %rbp,%rdi
  mov    %eax,%esi
  call   <strncat@plt>
  mov    %rbp,%rdi
  call   <sink@plt>
  mov    $0x1,%edi
  call   <string_range@plt>
  mov    $0x3,%edx
  mov    %rbp,%rdi
  mov    %eax,%esi
  call   <strncat@plt>
  mov    %rbp,%rdi
  call   <sink@plt>
  mov    $0x1,%edi
  call   <string_range@plt>
  mov    $0x4,%edx
  mov    %rbp,%rdi
  mov    %eax,%esi
  call   <strncat@plt>
  mov    %rbp,%rdi
  call   <sink@plt>
  mov    $0x1,%edi
  call   <string_range@plt>
  mov    $0x5,%edx
  mov    %rbp,%rdi
  mov    %eax,%esi
  call   <strncat@plt>
  mov    %rbp,%rdi
  call   <sink@plt>
  mov    $0x1,%edi
  call   <string_range@plt>
  mov    $0x6,%edx
  mov    %rbp,%rdi
  mov    %eax,%esi
  call   <strncat@plt>
  mov    %rbp,%rdi
  call   <sink@plt>
  mov    $0x2,%edi
  call   <string_range@plt>
  mov    $0x6,%edx
  mov    %rbp,%rdi
  mov    %eax,%esi
  call   <strncat@plt>
  mov    %rbp,%rdi
  call   <sink@plt>
  mov    $0x5,%edi
  call   <string_range@plt>
  mov    $0x6,%edx
  mov    %rbp,%rdi
  mov    %eax,%esi
  call   <strncat@plt>
  mov    %rbp,%rdi
  call   <sink@plt>
  mov    $0x7,%edi
  call   <string_range@plt>
  mov    $0x6,%edx
  mov    %rbp,%rdi
  mov    %eax,%esi
  call   <strncat@plt>
  mov    %rbp,%rdi
  call   <sink@plt>
  mov    $0x4,%edi
  movb   $0x0,0x17(%rsp)
  movl   $0x3231,0x13(%rsp)
  call   <string_range@plt>
  mov    %r12,%rdi
  mov    $0x4,%edx
  mov    %eax,%esi
  call   <strncat@plt>
  mov    %r12,%rdi
  call   <sink@plt>
  mov    0x18(%rsp),%rax
  sub    %fs:0x28,%rax
  jne    L7
  add    $0x28,%rsp
  pop    %rbp
  pop    %r12
  ret
L7:
  call   <__stack_chk_fail@plt>
```

assistant: ```c
void test_strncat_range(void) {
  char buf[5] = "";
  (strncat((buf), (string_range(0)), (0)), sink((buf)));
  (strncat((buf), (string_range(0)), (1)), sink((buf)));
  (strncat((buf), (string_range(0)), (2)), sink((buf)));
  (strncat((buf), (string_range(0)), (3)), sink((buf)));
  (strncat((buf), (string_range(0)), (4)), sink((buf)));
  (strncat((buf + 5), (string_range(0)), (0)), sink((buf + 5)));
  (strncat((buf + 5), (string_range(0)), (1)), sink((buf + 5)));
  (strncat((buf + 5), (string_range(1)), (1)), sink((buf + 5)));
  (strncat((buf), (string_range(0)), (5)), sink((buf)));
  (strncat((buf), (string_range(0)), (6)), sink((buf)));
  (strncat((buf), (string_range(1)), (0)), sink((buf)));
  (strncat((buf), (string_range(1)), (1)), sink((buf)));
  (strncat((buf), (string_range(1)), (2)), sink((buf)));
  (strncat((buf), (string_range(1)), (3)), sink((buf)));
  (strncat((buf), (string_range(1)), (4)), sink((buf)));
  (strncat((buf), (string_range(1)), (5)), sink((buf)));
  (strncat((buf), (string_range(1)), (6)), sink((buf)));
  (strncat((buf), (string_range(2)), (6)), sink((buf)));
  (strncat((buf), (string_range(5)), (6)), sink((buf)));
  (strncat((buf), (string_range(7)), (6)), sink((buf)));
  {
    char buf2[5] = "12";
    (strncat((buf2), (string_range(4)), (4)), sink((buf2)));
  }
}
```