Add _spectre_strtod to spectre utils

Copied from glib g_strtod(), a thread-safe locale-independent version
of the standard strtod().

2 files changed, 134 insertions, 8 deletions

diff --git a/libspectre/spectre-utils.c b/libspectre/spectre-utils.c
index 67750a8..0d8cf02 100644
--- a/libspectre/spectre-utils.c
+++ b/libspectre/spectre-utils.c
@@ -22,6 +22,8 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <errno.h>
+#include <locale.h>
 
 #include "spectre-utils.h"
 
@@ -250,3 +252,125 @@ _spectre_strcasecmp (const char *s1,
 
 	return (((int)(unsigned char) *s1) - ((int)(unsigned char) *s2));
 }
+
+#define ascii_isspace(c) \
+	(c == ' ' || c == '\f' || c == '\n' || c == '\r' || c == '\t' || c == '\v')
+#define ascii_isdigit(c) \
+	(c >= '0' && c <= '9')
+
+/* This function behaves like the standard strtod() function
+ * does in the C locale. It does this without actually changing
+ * the current locale, since that would not be thread-safe.
+ * A limitation of the implementation is that this function
+ * will still accept localized versions of infinities and NANs.
+ */
+double
+_spectre_strtod (const char *nptr,
+		 char      **endptr)
+{
+	char *fail_pos;
+	double val;
+	struct lconv *locale_data;
+	const char *decimal_point;
+	int decimal_point_len;
+	const char *p, *decimal_point_pos;
+	const char *end = NULL; /* Silence gcc */
+	int strtod_errno;
+
+	fail_pos = NULL;
+	
+	locale_data = localeconv ();
+	decimal_point = locale_data->decimal_point;
+	decimal_point_len = strlen (decimal_point);
+
+	decimal_point_pos = NULL;
+	end = NULL;
+
+	if (decimal_point[0] != '.' || decimal_point[1] != 0) {
+		p = nptr;
+		/* Skip leading space */
+		while (ascii_isspace (*p))
+			p++;
+
+		/* Skip leading optional sign */
+		if (*p == '+' || *p == '-')
+			p++;
+
+		if (ascii_isdigit (*p) || *p == '.') {
+			while (ascii_isdigit (*p))
+				p++;
+
+			if (*p == '.')
+				decimal_point_pos = p++;
+
+			while (ascii_isdigit (*p))
+				p++;
+
+			if (*p == 'e' || *p == 'E')
+				p++;
+			if (*p == '+' || *p == '-')
+				p++;
+			while (ascii_isdigit (*p))
+				p++;
+
+			end = p;
+		}
+		/* For the other cases, we need not convert the decimal point */
+	}
+
+	if (decimal_point_pos) {
+		char *copy, *c;
+
+		/* We need to convert the '.' to the locale specific decimal point */
+		copy = (char *) malloc (end - nptr + 1 + decimal_point_len);
+
+		c = copy;
+		memcpy (c, nptr, decimal_point_pos - nptr);
+		c += decimal_point_pos - nptr;
+		memcpy (c, decimal_point, decimal_point_len);
+		c += decimal_point_len;
+		memcpy (c, decimal_point_pos + 1, end - (decimal_point_pos + 1));
+		c += end - (decimal_point_pos + 1);
+		*c = 0;
+
+		errno = 0;
+		val = strtod (copy, &fail_pos);
+		strtod_errno = errno;
+
+		if (fail_pos) {
+			if (fail_pos - copy > decimal_point_pos - nptr)
+				fail_pos = (char *)nptr + (fail_pos - copy) - (decimal_point_len - 1);
+			else
+				fail_pos = (char *)nptr + (fail_pos - copy);
+		}
+
+		free (copy);
+	} else if (end)	{
+		char *copy;
+		
+		copy = (char *) malloc (end - (char *)nptr + 1);
+		memcpy (copy, nptr, end - nptr);
+		*(copy + (end - (char *)nptr)) = 0;
+		
+		errno = 0;
+		val = strtod (copy, &fail_pos);
+		strtod_errno = errno;
+		
+		if (fail_pos) {
+			fail_pos = (char *)nptr + (fail_pos - copy);
+		}
+
+		free (copy);
+	} else {
+		errno = 0;
+		val = strtod (nptr, &fail_pos);
+		strtod_errno = errno;
+	}
+
+	if (endptr)
+		*endptr = fail_pos;
+
+	errno = strtod_errno;
+
+	return val;
+}
diff --git a/libspectre/spectre-utils.h b/libspectre/spectre-utils.h
index bfaf9a4..3ed2da8 100644
--- a/libspectre/spectre-utils.h
+++ b/libspectre/spectre-utils.h
@@ -121,14 +121,16 @@ void _spectre_real_assert (int          condition,
 #endif /* SPECTRE_DISABLE_CHECKS */
 
 /* String handling helpers */
-char *_spectre_strdup_printf (const char *format,
-			      ...);
-char *_spectre_strdup        (const char *str);
-int   _spectre_strncasecmp   (const char *s1,
-			      const char *s2,
-			      size_t      n);
-int   _spectre_strcasecmp    (const char *s1,
-			      const char *s2);
+char  *_spectre_strdup_printf (const char *format,
+			       ...);
+char  *_spectre_strdup        (const char *str);
+int    _spectre_strncasecmp   (const char *s1,
+			       const char *s2,
+			       size_t      n);
+int    _spectre_strcasecmp    (const char *s1,
+			       const char *s2);
+double _spectre_strtod        (const char *nptr,
+			       char      **endptr);
 
 SPECTRE_END_DECLS