fusl/src/locale/setlocale.c

#include <locale.h>
#include <stdlib.h>
#include <string.h>
#include "locale_impl.h"
#include "libc.h"
#include "atomic.h"

static char buf[LC_ALL * (LOCALE_NAME_MAX + 1)];

static char* setlocale_one_unlocked(int cat, const char* name) {
  const struct __locale_map* lm;

  if (name)
    libc.global_locale.cat[cat] = lm = __get_locale(cat, name);
  else
    lm = libc.global_locale.cat[cat];

  return lm ? (char*)lm->name : "C";
}

char* __strchrnul(const char*, int);

char* setlocale(int cat, const char* name) {
  static volatile int lock[2];

  if ((unsigned)cat > LC_ALL)
    return 0;

  LOCK(lock);

  /* For LC_ALL, setlocale is required to return a string which
   * encodes the current setting for all categories. The format of
   * this string is unspecified, and only the following code, which
   * performs both the serialization and deserialization, depends
   * on the format, so it can easily be changed if needed. */
  if (cat == LC_ALL) {
    int i;
    if (name) {
      char part[LOCALE_NAME_MAX + 1] = "C.UTF-8";
      const char* p = name;
      for (i = 0; i < LC_ALL; i++) {
        const char* z = __strchrnul(p, ';');
        if (z - p <= LOCALE_NAME_MAX) {
          memcpy(part, p, z - p);
          part[z - p] = 0;
          if (*z)
            p = z + 1;
        }
        setlocale_one_unlocked(i, part);
      }
    }
    char* s = buf;
    for (i = 0; i < LC_ALL; i++) {
      const struct __locale_map* lm = libc.global_locale.cat[i];
      const char* part = lm ? lm->name : "C";
      size_t l = strlen(part);
      memcpy(s, part, l);
      s[l] = ';';
      s += l + 1;
    }
    *--s = 0;
    UNLOCK(lock);
    return buf;
  }

  char* ret = setlocale_one_unlocked(cat, name);

  UNLOCK(lock);

  return ret;
}