user: 请从给定的汇编指令推导出C源代码：

```asm
<expandpath>:
  endbr64
  push   %r14
  push   %r13
  push   %r12
  push   %rbp
  push   %rbx
  sub    $0x1000,%rsp
  orq    $0x0,(%rsp)
  sub    $0x10,%rsp
  movzbl (%rdi),%ebx
  movzbl 0x1(%rdi),%r13d
  mov    %fs:0x28,%rax
  mov    %rax,0x1008(%rsp)
  xor    %eax,%eax
  mov    %rdi,%rbp
  mov    %esi,%r12d
  call   <strlen@plt>
  cltq
  cmpb   $0x2f,-0x1(%rbp,%rax,1)
  jne    L13
  test   %r12d,%r12d
  jne    L156
L13:
  cmp    $0x7e,%bl
  je     L92
  cmp    $0x2f,%bl
  je     L217
  cmp    $0x2e,%bl
  jne    L164
  cmp    $0x2f,%r13b
  jne    L164
L229:
  mov    %rsp,%rdi
  mov    $0x1000,%esi
  call   <getcwd@plt>
  mov    %rax,%r13
L42:
  test   %r13,%r13
  je     L156
  mov    %r13,%rdi
  call   <strlen@plt>
  cmp    $0x1000,%eax
  jg     L156
  mov    %r13,%rdi
  call   <strlen@plt>
  mov    %rbp,%rdi
  mov    %eax,%ebx
  call   <strlen@plt>
  lea    (%rbx,%rax,1),%edi
  call   <malloc@plt>
  mov    %rax,%r12
  test   %rax,%rax
  je     L144
  lea    0x1(%rbp),%rcx
  mov    %r13,%rdx
  lea    D5(%rip),%rsi
  mov    %rax,%rdi
  call   <sprintf@plt>
  jmp    L144
  nop
L164:
  mov    $0x2f,%esi
  mov    %rbp,%rdi
  call   <strchr@plt>
  test   %eax,%eax
  je     L41
L87:
  cmp    $0x2e,%bl
  jne    L156
  cmp    $0x2f,%r13b
  je     L229
L156:
  xor    %r12d,%r12d
L144:
  mov    0x1008(%rsp),%rax
  sub    %fs:0x28,%rax
  jne    L225
  add    $0x1010,%rsp
  mov    %r12,%rax
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  ret
  nopl   (%rax)
L217:
  cmp    $0x7e,%bl
  je     L92
  cmp    $0x2e,%bl
  je     L92
L104:
  cmp    $0x2f,%bl
  jne    L156
  mov    %rbp,%rdi
  call   <strlen@plt>
  lea    0x1(%rax),%edi
  call   <malloc@plt>
  mov    %rax,%r12
  test   %rax,%rax
  je     L156
  mov    %rbp,%rdi
  call   <strlen@plt>
  cmp    $0x1000,%eax
  jg     L156
  mov    %rbp,%rsi
  mov    %r12,%rdi
  call   <strcpy@plt>
  jmp    L144
  nopl   0x0(%rax,%rax,1)
L92:
  cmp    $0x2f,%r13b
  jne    L104
  cmp    $0x7e,%bl
  jne    L229
  xor    %eax,%eax
  call   <getudir@plt>
  mov    %rax,%r13
  jmp    L42
  cs nopw 0x0(%rax,%rax,1)
L41:
  mov    %rsp,%r14
  mov    $0x1000,%esi
  mov    %r14,%rdi
  call   <getcwd@plt>
  test   %rax,%rax
  je     L87
  mov    %r14,%rdi
  call   <strlen@plt>
  mov    %rbp,%rdi
  mov    %eax,%r12d
  call   <strlen@plt>
  lea    0x2(%r12,%rax,1),%edi
  call   <malloc@plt>
  mov    %rax,%r12
  test   %rax,%rax
  je     L87
  mov    %rbp,%rcx
  mov    %r14,%rdx
  lea    D12(%rip),%rsi
  mov    %rax,%rdi
  call   <sprintf@plt>
  jmp    L144
L225:
  call   <__stack_chk_fail@plt>
```

tool_calls: name: read_data
arguments: label: D5
type_guessed: string
name: read_data
arguments: label: D12
type_guessed: string

tool: D5: %s%s

tool: D12: %s/%s

assistant: ```c
char *expandpath(char *path, int isfile) {
  char firstchar, secondchar, lastchar;
  char cwd[4096];
  char *dir = NULL;
  char *heap = NULL;
  int len = 0;
  firstchar = *path;
  secondchar = *(path + 1);
  lastchar = *(path + strlen(path) - 1);
  if (lastchar == '/' && isfile)
    return NULL;
  if (firstchar != '~' && firstchar != '/') {
    if (!(firstchar == '.' && secondchar == '/')) {
      if (!strchr(path, '/')) {
        if (getcwd(cwd, 4096)) {
          len = strlen(cwd) + strlen(path) + 2;
          if ((heap = malloc(len * sizeof(char)))) {
            sprintf(heap, "%s/%s", cwd, path);
            return heap;
          }
        }
      }
    }
  }
  if ((firstchar == '~' || firstchar == '.') && secondchar == '/') {
    if (firstchar == '~') {
      dir = getudir();
    } else {
      dir = getcwd(cwd, 4096);
    }
    if (dir) {
      if (strlen(dir) > 4096)
        return NULL;
      len = strlen(dir) + strlen(path);
      if ((heap = malloc(len * sizeof(char)))) {
        sprintf(heap, "%s%s", dir, path + 1);
        return heap;
      }
    }
  } else if (firstchar == '/') {
    heap = malloc((strlen(path) + 1) * sizeof(char));
    if (heap)
      if (strlen(path) <= 4096)
        return strcpy(heap, path);
  }
  return NULL;
}
```