1 files changed, 109 insertions, 0 deletions
diff --git a/lib/c_strtod.c b/lib/c_strtod.c
new file mode 100644
index 0000000..d25ee27
--- /dev/null
+++ b/lib/c_strtod.c
@@ -0,0 +1,109 @@
+/*
+ * Locale-independent strtod().
+ *
+ * This file may be redistributed under the terms of the
+ * GNU Lesser General Public License.
+ *
+ * Copyright (C) 2021 Karel Zak <kzak@redhat.com>
+ */
+#include "c.h"
+
+#include <locale.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "c_strtod.h"
+
+#ifdef __APPLE__
+# include <xlocale.h>
+#endif
+
+#if defined(HAVE_NEWLOCALE) && (defined(HAVE_STRTOD_L) || defined(HAVE_USELOCALE))
+# define USE_CLOCALE
+#endif
+
+#if defined(USE_CLOCALE)
+static volatile locale_t c_locale;
+
+static locale_t get_c_locale(void)
+{
+	if (!c_locale)
+		c_locale = newlocale(LC_ALL_MASK, "C", (locale_t) 0);
+	return c_locale;
+}
+#endif
+
+
+double c_strtod(char const *str, char **end)
+{
+	double res;
+	int errsv;
+
+#if defined(USE_CLOCALE)
+	locale_t cl = get_c_locale();
+
+#if defined(HAVE_STRTOD_L)
+	/*
+	 * A) try strtod_l() for "C" locale
+	 */
+	if (cl)
+		return strtod_l(str, end, cl);
+#elif defined(HAVE_USELOCALE)
+	/*
+	 * B) classic strtod(), but switch to "C" locale by uselocal()
+	 */
+	if (cl) {
+		locale_t org_cl = uselocale(locale);
+		if (!org_cl)
+			return 0;
+
+		res = strtod(str, end);
+		errsv = errno;
+
+		uselocale(org_cl);
+		errno = errsv;
+		return res;
+	}
+#endif /* HAVE_USELOCALE */
+#endif /* USE_CLOCALE */
+	/*
+	 * C) classic strtod(), but switch to "C" locale by setlocale()
+	 */
+	char *org_locale = setlocale(LC_NUMERIC, NULL);
+
+	if (org_locale) {
+		org_locale = strdup(org_locale);
+		if (!org_locale)
+			return 0;
+
+		setlocale(LC_NUMERIC, "C");
+	}
+	res = strtod(str, end);
+	errsv = errno;
+
+	if (org_locale) {
+		setlocale(LC_NUMERIC, org_locale);
+		free(org_locale);
+	}
+	errno = errsv;
+	return res;
+}
+
+#ifdef TEST_PROGRAM
+int main(int argc, char *argv[])
+{
+	double res;
+	char *end;
+
+	if (argc < 2) {
+		fprintf(stderr, "usage: %s decimal.number\n",
+				program_invocation_short_name);
+		return EXIT_FAILURE;
+	}
+
+	res = c_strtod(argv[1], &end);
+	printf("Result: %g, errno: %d, endptr: '%s'\n", res, errno, end);
+
+	return errno ? EXIT_FAILURE : EXIT_SUCCESS;
+}
+#endif