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

```asm
<main>:
  endbr64
  push   %rbp
  mov    %rsp,%rbp
  sub    $0x30,%rsp
  mov    %edi,-0x24(%rbp)
  mov    %rsi,-0x30(%rbp)
  movq   $0x0,-0x10(%rbp)
  movl   $0x0,-0x1c(%rbp)
  cmpl   $0x1,-0x24(%rbp)
  jle    L75
  mov    -0x30(%rbp),%rax
  mov    0x8(%rax),%rax
  mov    %rax,-0x10(%rbp)
L75:
  cmpq   $0x0,-0x10(%rbp)
  je     L9
  mov    -0x10(%rbp),%rax
  movzbl (%rax),%eax
  test   %al,%al
  je     L9
  mov    D91(%rip),%rax
  mov    (%rax),%edx
  mov    D57(%rip),%rax
  mov    (%rax),%eax
  or     %eax,%edx
  mov    D29(%rip),%rax
  mov    (%rax),%ecx
  mov    D30(%rip),%rax
  mov    (%rax),%eax
  or     %eax,%ecx
  mov    D128(%rip),%rax
  mov    (%rax),%eax
  or     %eax,%ecx
  mov    -0x10(%rbp),%rax
  mov    %ecx,%esi
  mov    %rax,%rdi
  call   <open@plt>
  mov    %eax,-0x1c(%rbp)
  cmpl   $0x0,-0x1c(%rbp)
  jns    L9
  mov    D28(%rip),%rax
  mov    (%rax),%eax
  mov    %eax,%edi
  call   <strerror@plt>
  mov    %eax,%edi
  call   <perror@plt>
L9:
  mov    D50(%rip),%rax
  mov    (%rax),%eax
  mov    %eax,%edi
  call   <sysconf@plt>
  mov    %eax,-0x18(%rbp)
  mov    D47(%rip),%rax
  mov    (%rax),%edx
  mov    D16(%rip),%rax
  mov    (%rax),%eax
  mov    %edx,%ecx
  or     %eax,%ecx
  mov    D132(%rip),%rax
  mov    (%rax),%edx
  mov    D113(%rip),%rax
  mov    (%rax),%eax
  or     %eax,%edx
  mov    -0x18(%rbp),%eax
  mov    $0x0,%r9d
  mov    $0xffffffff,%r8d
  mov    %eax,%esi
  mov    $0x0,%edi
  call   <mmap@plt>
  mov    %rax,-0x8(%rbp)
  cmpq   $0x0,-0x8(%rbp)
  jne    L38
  mov    D28(%rip),%rax
  mov    (%rax),%eax
  mov    %eax,%edi
  call   <strerror@plt>
  mov    %eax,%edi
  call   <perror@plt>
L38:
  movl   $0x0,-0x14(%rbp)
  jmp    L29
L20:
  cmpl   $0x0,-0x1c(%rbp)
  jle    L43
  mov    -0x14(%rbp),%edx
  mov    -0x8(%rbp),%rcx
  mov    -0x1c(%rbp),%eax
  mov    %rcx,%rsi
  mov    %eax,%edi
  call   <write@plt>
L43:
  mov    D122(%rip),%rax
  mov    (%rax),%eax
  mov    -0x14(%rbp),%edx
  mov    -0x8(%rbp),%rcx
  mov    %rcx,%rsi
  mov    %eax,%edi
  call   <write@plt>
L29:
  mov    D38(%rip),%rax
  mov    (%rax),%eax
  mov    -0x18(%rbp),%edx
  mov    -0x8(%rbp),%rcx
  mov    %rcx,%rsi
  mov    %eax,%edi
  call   <read@plt>
  mov    %eax,-0x14(%rbp)
  cmpl   $0x0,-0x14(%rbp)
  jg     L20
  cmpl   $0x0,-0x1c(%rbp)
  jle    L44
  mov    -0x1c(%rbp),%eax
  mov    %eax,%edi
  call   <close@plt>
  movl   $0xffffffff,-0x1c(%rbp)
L44:
  mov    $0x0,%eax
  leave
  ret
```

assistant: ```c
int main(int argc, void **args) {
  char *file_name = NULL;
  int fd = 0;
  if (argc > 1)
    file_name = (char *)args[1];
  if (file_name && strlen(file_name)) {
    fd = open(file_name, O_CREAT | O_WRONLY | O_APPEND, S_IRUSR | S_IWUSR);
    if (fd < 0)
      perror(strerror(errno));
  }
  int buff_sz = sysconf(_SC_PAGE_SIZE);
  char *buff = mmap(NULL, buff_sz, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
  if (NULL == buff) {
    perror(strerror(errno));
  }
  ssize_t read_sz = 0;
  while ((read_sz = read(STDIN_FILENO, buff, buff_sz)) > 0) {
    if (fd > 0)
      write(fd, buff, read_sz);
    write(STDOUT_FILENO, buff, read_sz);
  }
  if (fd > 0) {
    close(fd);
    fd = -1;
  }
  return 0;
}
```