CODEWITHSUNDEEP
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trupanka
trupanka

Reputation: 703

segfault reading wide-oriented stream with locale settings

I have problem in program with locale and reading from stdin with fgetws function.

#include <stdio.h>
#include <locale.h>
#include <wchar.h>

static const int N = 2;

int main(void) {
  setlocale(LC_ALL, "");
  wchar_t data[N];
  fgetws(data, N, stdin);
  printf("%ls\n", data);
  /* fclose(stdin); */
  return 0;
}

When input is long enough (5 or more chars) I get segfault if I don't close stdin before return. Why is that? What is wrong with this program?

Upvotes: 0

Views: 87

Answers (1)

chux
chux

Reputation: 154146

Suspect fgetws(data, 2, stdin) is broken.

fgetws(), using such a small buffer should, at most, read 1 wchar_t from stdin and append a termanting (wchar_t) '\0'.

As usual, when code fails mysteriously, best to check return from the functions to see if they are as expected.

#include <stdio.h>
#include <locale.h>
#include <wchar.h>

#include <assert.h>
#include <stdio.h>
#include <locale.h>
#include <wchar.h>

static const int N = 2;

int main(void) {
  char *p = setlocale(LC_ALL, "");
  assert(p);

  wchar_t data[N];
  wchar_t *s = fgetws(data, N, stdin);
  assert(s); 

  int i = printf("%ls\n", data);
  assert(i == 2);

  i = fclose(stdin);
  assert(i == 0);
  return 0;
}

Upvotes: 1

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