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

```asm
<write_vtkHeader>:
  endbr64
  push   %r13
  push   %r12
  push   %rbp
  push   %rbx
  sub    $0x68,%rsp
  mov    %fs:0x28,%rax
  mov    %rax,0x58(%rsp)
  xor    %eax,%eax
  test   %rdi,%rdi
  je     L21
  mov    %rdi,%rbx
  mov    %esi,%r12d
  mov    %edx,%ebp
  mov    %ecx,%r13d
  mov    %rdi,%rcx
  mov    $0x1b,%edx
  mov    $0x1,%esi
  lea    D59(%rip),%rdi
  call   <fwrite@plt>
  mov    %rbx,%rcx
  mov    $0x24,%edx
  mov    $0x1,%esi
  lea    D9(%rip),%rdi
  call   <fwrite@plt>
  mov    %rbx,%rcx
  mov    $0x6,%edx
  mov    $0x1,%esi
  lea    D37(%rip),%rdi
  call   <fwrite@plt>
  mov    %rbx,%rsi
  mov    $0xa,%edi
  call   <fputc@plt>
  mov    %rbx,%rcx
  mov    $0x18,%edx
  mov    $0x1,%esi
  lea    D67(%rip),%rdi
  call   <fwrite@plt>
  add    $0x1,%r13d
  add    $0x1,%ebp
  add    $0x1,%r12d
  mov    %r13d,%r8d
  mov    %ebp,%ecx
  mov    %r12d,%edx
  lea    D2(%rip),%rsi
  mov    %rbx,%rdi
  mov    $0x0,%eax
  call   <fprintf@plt>
  mov    %ebp,%edx
  imul   %r12d,%edx
  imul   %r13d,%edx
  lea    D78(%rip),%rsi
  mov    %rbx,%rdi
  mov    $0x0,%eax
  call   <fprintf@plt>
  mov    %rbx,%rsi
  mov    $0xa,%edi
  call   <fputc@plt>
L18:
  mov    0x58(%rsp),%rax
  sub    %fs:0x28,%rax
  jne    L16
  add    $0x68,%rsp
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  ret
L21:
  mov    %rsp,%rbx
  lea    D16(%rip),%rsi
  mov    %rbx,%rdi
  call   <sprintf@plt>
  mov    %rbx,%rdx
  lea    D79(%rip),%rsi
  mov    $0x1f2,%edi
  call   <errhandler@plt>
  jmp    L18
L16:
  call   <__stack_chk_fail@plt>
```

tool_calls: name: disassemble_data
arguments: label: D59
type_guessed: string
name: disassemble_data
arguments: label: D9
type_guessed: string
name: disassemble_data
arguments: label: D37
type_guessed: string
name: disassemble_data
arguments: label: D67
type_guessed: string
name: disassemble_data
arguments: label: D2
type_guessed: string
name: disassemble_data
arguments: label: D78
type_guessed: string
name: disassemble_data
arguments: label: D16
type_guessed: string
name: disassemble_data
arguments: label: D79
type_guessed: string

tool: D59: # vtk DataFile Version 2.0


tool: D9: generated by CFD-lab course output 


tool: D37: ASCII


tool: D67: DATASET STRUCTURED_GRID


tool: D2: DIMENSIONS  %i %i %i 


tool: D78: POINTS %i float


tool: D16: Null pointer in write_vtkHeader

tool: D79: /scratch/repos/new/home/jordi_armengol_estape/c-scraper/outputs/2022-01-22/02-19-57/repos/EvaBr/CFD-Lab/refs/heads/master/FinalProject/visual.c

assistant: ```c
void write_vtkHeader(FILE *fp, int imax, int jmax, int kmax, double dx, double dy, double dz) {
  if (fp == NULL) {
    char szBuff[80];
    sprintf(szBuff, "Null pointer in write_vtkHeader");
    errhandler(498, "/scratch/repos/new/home/jordi_armengol_estape/c-scraper/outputs/2022-01-22/02-19-57/repos/EvaBr/CFD-Lab/refs/heads/master/FinalProject/visual.c", szBuff);
    return;
  }
  fprintf(fp, "# vtk DataFile Version 2.0\n");
  fprintf(fp, "generated by CFD-lab course output \n");
  fprintf(fp, "ASCII\n");
  fprintf(fp, "\n");
  fprintf(fp, "DATASET STRUCTURED_GRID\n");
  fprintf(fp, "DIMENSIONS  %i %i %i \n", imax + 1, jmax + 1, kmax + 1);
  fprintf(fp, "POINTS %i float\n", (imax + 1) * (jmax + 1) * (kmax + 1));
  fprintf(fp, "\n");
}
```