user: Translate the below assembly code into C programming language:

```asm
<SubVar>:
  endbr64
  push   %r15
  mov    %r8,%r15
  push   %r14
  mov    %rdx,%r14
  push   %r13
  push   %r12
  mov    %rcx,%r12
  push   %rbp
  mov    %rsi,%rbp
  push   %rbx
  mov    %edi,%ebx
  mov    %rcx,%rdi
  sub    $0x28,%rsp
  mov    %rdx,0x18(%rsp)
  call   <strlen@plt>
  mov    %r14,%rdi
  mov    %rax,%r13
  call   <strlen@plt>
  mov    %rbp,%rdi
  mov    (%r15),%r14d
  mov    %rax,(%rsp)
  call   <strlen@plt>
  mov    (%rsp),%rcx
  sub    %eax,%r13d
  lea    -0x1(%r13,%rcx,1),%eax
  cmp    %eax,%r14d
  jle    L15
L67:
  movslq %r14d,%rdi
  lea    D15(%rip),%r15
  call   <malloc@plt>
  mov    %r12,%rsi
  mov    %rax,%r14
  mov    %rax,%rdi
  call   <strcpy@plt>
  movzbl (%r14),%eax
  mov    %r14,%r13
  test   %al,%al
  jne    L107
  jmp    L14
  cs nopw 0x0(%rax,%rax,1)
L58:
  mov    %r8,%r13
  movzbl 0x0(%r13),%eax
  test   %al,%al
  je     L14
L107:
  lea    0x1(%r13),%r8
  cmp    %al,%bl
  jne    L58
  cmp    %r13,%r14
  jae    L28
  cmpb   $0x5c,-0x1(%r13)
  je     L58
L28:
  mov    %r8,%rdi
  mov    %r15,%rsi
  mov    %r8,0x8(%rsp)
  call   <strcspn@plt>
  mov    0x8(%rsp),%rsi
  mov    %rbp,%rdi
  cltq
  lea    0x1(%r13,%rax,1),%rcx
  movzbl (%rcx),%eax
  movb   $0x0,(%rcx)
  mov    %rcx,(%rsp)
  mov    %al,0x17(%rsp)
  call   <strcasecmp@plt>
  mov    (%rsp),%rcx
  lea    0x1(%rcx),%r9
  test   %eax,%eax
  je     L46
  movzbl 0x17(%rsp),%eax
  mov    %al,(%rcx)
L70:
  mov    %r9,%r13
  movzbl 0x0(%r13),%eax
  test   %al,%al
  jne    L107
L14:
  mov    %r14,%rdi
  call   <free@plt>
  add    $0x28,%rsp
  mov    %r12,%rax
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
  nopl   0x0(%rax,%rax,1)
L46:
  movb   $0x0,0x0(%r13)
  mov    0x18(%rsp),%rcx
  mov    %r14,%rdx
  mov    %r12,%rdi
  movsbl 0x17(%rsp),%r8d
  lea    D13(%rip),%rsi
  mov    %r9,(%rsp)
  call   <sprintf@plt>
  mov    %r12,%rsi
  mov    %r14,%rdi
  call   <strcpy@plt>
  mov    (%rsp),%r9
  jmp    L70
  nopw   0x0(%rax,%rax,1)
L15:
  mov    $0x200,%eax
  mov    %r12,%rdi
  cmp    %eax,%ecx
  cmovge %ecx,%eax
  lea    (%r14,%rax,1),%edx
  mov    %eax,%r13d
  movslq %edx,%rsi
  call   <realloc@plt>
  mov    (%r15),%r14d
  mov    %rax,%r12
  add    %r13d,%r14d
  mov    %r14d,(%r15)
  jmp    L67
```

tool_calls: name: extract_symbolic_data
arguments: label: D15
datatype: string
name: extract_symbolic_data
arguments: label: D13
datatype: string

tool: D15:  ,()'
:;.{}[]-+=~!@#$%^*<>"

tool: D13: %s%s%c%s

assistant: ```c
char *SubVar(char sep, char *var_name, char *var_value, char *oldbuf, int *bufsize) {
  char *buf, *s, *t;
  int l, n;
  char o;
  char *local_buf;
  l = strlen(oldbuf);
  n = strlen(var_value);
  if (l - (int)strlen(var_name) - 1 + (int)strlen(var_value) > (int)(*bufsize - 1)) {
    buf = realloc(oldbuf, *bufsize + ((n > 512) ? n : 512));
    *bufsize += ((n > 512) ? n : 512);
  } else
    buf = oldbuf;
  local_buf = malloc(*bufsize * sizeof(char));
  strcpy(local_buf, buf);
  if (!local_buf) {
    html_error("FI Error", "Unable to allocate memory");
    exit(-1);
  }
  s = local_buf;
  while (*s != '\0') {
    if (*s == sep) {
      if (s > local_buf && *(s - 1) == '\\') {
        s++;
        continue;
      }
      n = strcspn(s + 1, " ,()'\n:;.{}[]-+=~!@#$%^*<>\"");
      t = s + n + 1;
      o = *t;
      *t = '\0';
      if (!strcasecmp(var_name, s + 1)) {
        *s = '\0';
        sprintf(buf, "%s%s%c%s", local_buf, var_value, o, t + 1);
        strcpy(local_buf, buf);
      } else {
        *t = o;
      }
      s = t + 1;
    } else
      s++;
  }
  free(local_buf);
  return (buf);
}
```