user: Please show me the C implementation that matches the assembly code listed below:

```asm
<DWBhome>:
  endbr64
  push   %r15
  push   %r14
  push   %r13
  push   %r12
  push   %rbp
  push   %rbx
  sub    $0xf8,%rsp
  mov    %fs:0x28,%rax
  mov    %rax,0xe8(%rsp)
  xor    %eax,%eax
  lea    D26(%rip),%rsi
  lea    D2(%rip),%rdi
  call   <fopen@plt>
  test   %rax,%rax
  je     L100
  mov    %rax,%r12
  lea    D25(%rip),%rdi
  call   <strlen@plt>
  mov    %eax,%r13d
  mov    $0x0,%ebp
  lea    0x20(%rsp),%r14
  lea    D25(%rip),%r15
  cltq
  mov    %rax,0x8(%rsp)
  add    $0x1,%rax
  mov    %rax,0x10(%rsp)
  jmp    L66
L185:
  add    $0x1,%rbx
L132:
  movsbl (%rbx),%edi
  call   <isspace@plt>
  test   %rax,%rax
  jne    L185
  mov    %r13d,%edx
  mov    %r15,%rsi
  mov    %rbx,%rdi
  call   <strncmp@plt>
  test   %rax,%rax
  jne    L66
  mov    0x8(%rsp),%rax
  cmpb   $0x3d,(%rbx,%rax,1)
  je     L175
L66:
  mov    %r12,%rdx
  mov    $0xc8,%esi
  mov    %r14,%rdi
  call   <fgets@plt>
  test   %rax,%rax
  je     L37
  lea    0x20(%rsp),%rbx
  jmp    L132
L175:
  add    0x10(%rsp),%rbx
  mov    %rbx,0x18(%rsp)
L44:
  movsbl (%rbx),%edi
  call   <isspace@plt>
  test   %rax,%rax
  jne    L134
  cmpb   $0x3b,(%rbx)
  je     L134
  add    $0x1,%rbx
  jmp    L44
L134:
  movb   $0x0,(%rbx)
  test   %rbp,%rbp
  je     L140
  mov    %rbp,%rdi
  call   <free@plt>
L140:
  mov    0x18(%rsp),%rbx
  mov    %rbx,%rdi
  call   <strlen@plt>
  lea    0x1(%rax),%edi
  call   <malloc@plt>
  mov    %rax,%rbp
  test   %rax,%rax
  je     L66
  mov    %rbx,%rsi
  mov    %rax,%rdi
  call   <strcpy@plt>
  jmp    L66
L37:
  mov    %r12,%rdi
  call   <fclose@plt>
  test   %rbp,%rbp
  jne    L78
L100:
  lea    D25(%rip),%rdi
  call   <getenv@plt>
  mov    %rax,%rbp
  test   %rax,%rax
  jne    L78
  jmp    L70
L9:
  add    $0x1,%rbp
L78:
  cmpb   $0x2f,0x0(%rbp)
  jne    L70
  cmpb   $0x2f,0x1(%rbp)
  je     L9
L70:
  mov    0xe8(%rsp),%rax
  sub    %fs:0x28,%rax
  jne    L139
  mov    %rbp,%rax
  add    $0xf8,%rsp
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
L139:
  call   <__stack_chk_fail@plt>
```

tool_calls: name: unpack_data
arguments: data_label: D26
type_guessed: string
name: unpack_data
arguments: data_label: D2
type_guessed: string
name: unpack_data
arguments: data_label: D25
type_guessed: string

tool: D26: r

tool: D2: /dev/null

tool: D25: DWBHOME

assistant: ```c
char *DWBhome(void) {
  FILE *fp;
  char *ptr;
  char *path;
  int len;
  char buf[200];
  char *home = NULL;
  if ((fp = fopen("/dev/null", "r")) != NULL) {
    len = strlen("DWBHOME");
    while (fgets(buf, sizeof(buf), fp) != NULL) {
      for (ptr = buf; isspace(*ptr); ptr++)
        ;
      if (strncmp(ptr, "DWBHOME", len) == 0 && *(ptr + len) == '=') {
        path = ptr + len + 1;
        for (ptr = path; !isspace(*ptr) && *ptr != ';'; ptr++)
          ;
        *ptr = '\0';
        if (home != NULL)
          free(home);
        if ((home = malloc(strlen(path) + 1)) != NULL)
          strcpy(home, path);
      }
    }
    fclose(fp);
  }
  if (home == NULL) {
    if ((home = getenv("DWBHOME")) == NULL) {
      if ((home = "") == NULL || *home == '\0' || *home == ' ')
        home = NULL;
    }
  }
  while (home && *home == '/' && *(home + 1) == '/')
    home++;
  return (home);
}
```