fusl/src/ldso/dlerror.c

#include <dlfcn.h>
#include <stdlib.h>
#include <stdarg.h>
#include "pthread_impl.h"
#include "libc.h"

char* dlerror() {
  pthread_t self = __pthread_self();
  if (!self->dlerror_flag)
    return 0;
  self->dlerror_flag = 0;
  char* s = self->dlerror_buf;
  if (s == (void*)-1)
    return "Dynamic linker failed to allocate memory for error message";
  else
    return s;
}

void __dl_thread_cleanup(void) {
  pthread_t self = __pthread_self();
  if (self->dlerror_buf != (void*)-1)
    free(self->dlerror_buf);
}

__attribute__((__visibility__("hidden"))) void __dl_vseterr(const char* fmt,
                                                            va_list ap) {
  va_list ap2;
  va_copy(ap2, ap);
  pthread_t self = __pthread_self();
  if (self->dlerror_buf != (void*)-1)
    free(self->dlerror_buf);
  size_t len = vsnprintf(0, 0, fmt, ap2);
  va_end(ap2);
  char* buf = malloc(len + 1);
  if (buf) {
    vsnprintf(buf, len + 1, fmt, ap);
  } else {
    buf = (void*)-1;
  }
  self->dlerror_buf = buf;
  self->dlerror_flag = 1;
}

__attribute__((__visibility__("hidden"))) void __dl_seterr(const char* fmt,
                                                           ...) {
  va_list ap;
  va_start(ap, fmt);
  __dl_vseterr(fmt, ap);
  va_end(ap);
}

__attribute__((__visibility__("hidden"))) int __dl_invalid_handle(void*);

static int stub_invalid_handle(void* h) {
  __dl_seterr("Invalid library handle %p", (void*)h);
  return 1;
}

weak_alias(stub_invalid_handle, __dl_invalid_handle);