user: What would the C source look like for the assembly code provided here:

```asm
<substringx>:
  endbr64
  push   %rbp
  mov    %rsp,%rbp
  push   %rbx
  sub    $0x58,%rsp
  mov    %rdi,-0x48(%rbp)
  mov    %rsi,-0x50(%rbp)
  mov    %rdx,-0x58(%rbp)
  mov    %ecx,-0x5c(%rbp)
  mov    %fs:0x28,%rax
  mov    %rax,-0x18(%rbp)
  xor    %eax,%eax
  cmpl   $0x32,-0x5c(%rbp)
  jle    L5
  mov    -0x48(%rbp),%rax
  mov    (%rax),%rax
  mov    %rax,%rsi
  lea    D4(%rip),%rax
  mov    %rax,%rdi
  mov    $0x0,%eax
  call   <fatalx@plt>
L5:
  mov    -0x48(%rbp),%rax
  mov    (%rax),%rax
  mov    %rax,-0x30(%rbp)
  mov    -0x30(%rbp),%rax
  mov    %rax,%rdi
  call   <strlen@plt>
  mov    %eax,%ebx
  mov    -0x50(%rbp),%rax
  mov    %rax,%rdi
  call   <strlen@plt>
  add    %eax,%ebx
  mov    -0x58(%rbp),%rax
  mov    %rax,%rdi
  call   <strlen@plt>
  add    %ebx,%eax
  add    $0x1,%eax
  mov    %eax,-0x3c(%rbp)
  mov    -0x30(%rbp),%rax
  mov    -0x50(%rbp),%rdx
  mov    %rdx,%rsi
  mov    %rax,%rdi
  call   <strstr@plt>
  mov    %rax,-0x28(%rbp)
  cmpq   $0x0,-0x28(%rbp)
  jne    L11
  mov    $0x0,%eax
  jmp    L36
L11:
  mov    -0x3c(%rbp),%eax
  mov    $0x1,%esi
  mov    %eax,%edi
  call   <calloc@plt>
  mov    %rax,-0x20(%rbp)
  cmpq   $0x0,-0x20(%rbp)
  jne    L49
  mov    -0x3c(%rbp),%eax
  mov    %eax,%esi
  lea    D9(%rip),%rax
  mov    %rax,%rdi
  mov    $0x0,%eax
  call   <fatalx@plt>
L49:
  mov    -0x30(%rbp),%rdx
  mov    -0x28(%rbp),%rax
  sub    %rdx,%rax
  mov    %eax,-0x38(%rbp)
  mov    -0x30(%rbp),%rcx
  mov    -0x38(%rbp),%edx
  mov    -0x20(%rbp),%rax
  mov    %rcx,%rsi
  mov    %rax,%rdi
  call   <strncpy@plt>
  mov    -0x38(%rbp),%eax
  movslq %eax,%rdx
  mov    -0x20(%rbp),%rax
  add    %rax,%rdx
  mov    -0x58(%rbp),%rax
  mov    %rax,%rsi
  mov    %rdx,%rdi
  call   <strcpy@plt>
  mov    -0x58(%rbp),%rax
  mov    %rax,%rdi
  call   <strlen@plt>
  mov    %eax,-0x34(%rbp)
  mov    -0x50(%rbp),%rax
  mov    %rax,%rdi
  call   <strlen@plt>
  cltq
  add    %rax,-0x28(%rbp)
  mov    -0x38(%rbp),%eax
  movslq %eax,%rdx
  mov    -0x34(%rbp),%eax
  cltq
  add    %rax,%rdx
  mov    -0x20(%rbp),%rax
  add    %rax,%rdx
  mov    -0x28(%rbp),%rax
  mov    %rax,%rsi
  mov    %rdx,%rdi
  call   <strcpy@plt>
  lea    -0x30(%rbp),%rax
  mov    %rax,%rdi
  call   <freestring@plt>
  mov    -0x20(%rbp),%rax
  mov    %rax,%rdi
  call   <strdup@plt>
  mov    %rax,%rdx
  mov    -0x48(%rbp),%rax
  mov    %rdx,(%rax)
  mov    -0x20(%rbp),%rax
  mov    %rax,%rdi
  call   <free@plt>
  mov    -0x5c(%rbp),%eax
  lea    0x1(%rax),%ecx
  mov    -0x58(%rbp),%rdx
  mov    -0x50(%rbp),%rsi
  mov    -0x48(%rbp),%rax
  mov    %rax,%rdi
  call   <substringx>
  add    $0x1,%eax
L36:
  mov    -0x18(%rbp),%rdx
  sub    %fs:0x28,%rdx
  je     L20
  call   <__stack_chk_fail@plt>
L20:
  mov    -0x8(%rbp),%rbx
  leave
  ret
```

tool_calls: name: parse_data
arguments: data_label: D4
datatype: string
name: parse_data
arguments: data_label: D9
datatype: string

tool: D4: bad string replacement
 %s


tool: D9: Unable to allocate %d unit(s) for item 


assistant: ```c
int substringx(char **ap, char *inx, char *outx, int niter) {
  char *a, *pt;
  char *str;
  int len, off, x;
  if (niter > 50)
    fatalx("bad string replacement\n %s\n", *ap);
  a = *ap;
  len = strlen(a) + strlen(inx) + strlen(outx) + 1;
  pt = strstr(a, inx);
  if (pt == NULL) {
    return 0;
  }
  if ((str = (char *)calloc((len), sizeof(char))) == NULL)
    fatalx("Unable to allocate %d unit(s) for item \n", len);
  off = pt - a;
  strncpy(str, a, off);
  strcpy(str + off, outx);
  x = strlen(outx);
  pt += strlen(inx);
  strcpy(str + off + x, pt);
  freestring(&a);
  *ap = strdup(str);
  free(str);
  return (1 + substringx(ap, inx, outx, niter + 1));
}
```