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

```asm
<DWBhome>:
  endbr64
  push   %rbp
  mov    %rsp,%rbp
  sub    $0x100,%rsp
  mov    %fs:0x28,%rax
  mov    %rax,-0x8(%rbp)
  xor    %eax,%eax
  movq   $0x0,-0xe8(%rbp)
  lea    D31(%rip),%rax
  mov    %rax,%rsi
  lea    D0(%rip),%rax
  mov    %rax,%rdi
  call   <fopen@plt>
  mov    %rax,-0xe0(%rbp)
  cmpq   $0x0,-0xe0(%rbp)
  je     L166
  lea    D48(%rip),%rax
  mov    %rax,%rdi
  call   <strlen@plt>
  mov    %eax,-0xf4(%rbp)
  jmp    L12
L84:
  lea    -0xd0(%rbp),%rax
  mov    %rax,-0xf0(%rbp)
  jmp    L153
L123:
  addq   $0x1,-0xf0(%rbp)
L153:
  mov    -0xf0(%rbp),%rax
  movzbl (%rax),%eax
  movsbl %al,%eax
  mov    %eax,%edi
  call   <isspace@plt>
  test   %rax,%rax
  jne    L123
  mov    -0xf4(%rbp),%edx
  mov    -0xf0(%rbp),%rax
  lea    D48(%rip),%rcx
  mov    %rcx,%rsi
  mov    %rax,%rdi
  call   <strncmp@plt>
  test   %rax,%rax
  jne    L12
  mov    -0xf4(%rbp),%eax
  movslq %eax,%rdx
  mov    -0xf0(%rbp),%rax
  add    %rdx,%rax
  movzbl (%rax),%eax
  cmp    $0x3d,%al
  jne    L12
  mov    -0xf4(%rbp),%eax
  cltq
  lea    0x1(%rax),%rdx
  mov    -0xf0(%rbp),%rax
  add    %rdx,%rax
  mov    %rax,-0xd8(%rbp)
  mov    -0xd8(%rbp),%rax
  mov    %rax,-0xf0(%rbp)
  jmp    L163
L134:
  addq   $0x1,-0xf0(%rbp)
L163:
  mov    -0xf0(%rbp),%rax
  movzbl (%rax),%eax
  movsbl %al,%eax
  mov    %eax,%edi
  call   <isspace@plt>
  test   %rax,%rax
  jne    L86
  mov    -0xf0(%rbp),%rax
  movzbl (%rax),%eax
  cmp    $0x3b,%al
  jne    L134
L86:
  mov    -0xf0(%rbp),%rax
  movb   $0x0,(%rax)
  cmpq   $0x0,-0xe8(%rbp)
  je     L17
  mov    -0xe8(%rbp),%rax
  mov    %rax,%rdi
  call   <free@plt>
L17:
  mov    -0xd8(%rbp),%rax
  mov    %rax,%rdi
  call   <strlen@plt>
  add    $0x1,%eax
  mov    %eax,%edi
  call   <malloc@plt>
  mov    %rax,-0xe8(%rbp)
  cmpq   $0x0,-0xe8(%rbp)
  je     L12
  mov    -0xd8(%rbp),%rdx
  mov    -0xe8(%rbp),%rax
  mov    %rdx,%rsi
  mov    %rax,%rdi
  call   <strcpy@plt>
L12:
  mov    -0xe0(%rbp),%rdx
  lea    -0xd0(%rbp),%rax
  mov    $0xc8,%esi
  mov    %rax,%rdi
  call   <fgets@plt>
  test   %rax,%rax
  jne    L84
  mov    -0xe0(%rbp),%rax
  mov    %rax,%rdi
  call   <fclose@plt>
L166:
  cmpq   $0x0,-0xe8(%rbp)
  jne    L39
  lea    D48(%rip),%rax
  mov    %rax,%rdi
  call   <getenv@plt>
  mov    %rax,-0xe8(%rbp)
  cmpq   $0x0,-0xe8(%rbp)
  jne    L39
  lea    D21(%rip),%rax
  mov    %rax,-0xe8(%rbp)
  mov    -0xe8(%rbp),%rax
  movzbl (%rax),%eax
  test   %al,%al
  je     L62
  mov    -0xe8(%rbp),%rax
  movzbl (%rax),%eax
  cmp    $0x20,%al
  jne    L39
L62:
  movq   $0x0,-0xe8(%rbp)
L39:
  mov    -0xe8(%rbp),%rax
  mov    -0x8(%rbp),%rdx
  sub    %fs:0x28,%rdx
  je     L1
  call   <__stack_chk_fail@plt>
L1:
  leave
  ret
```

tool_calls: name: extract_symbolic_data
arguments: tag: D31
datatype: string
name: extract_symbolic_data
arguments: tag: D0
datatype: string
name: extract_symbolic_data
arguments: tag: D48
datatype: string
name: extract_symbolic_data
arguments: tag: D21
datatype: string

tool: D31: r

tool: D0: /dev/null

tool: D48: DWBHOME

tool: 

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;
    }
  }
  return (home);
}
```