Avoid locale problems by inlining an old BSD version of strtod().

This solves Berlios tracker bug #18328: Wrong/bad locale handling in
json_read_object. All regression tests (including the JSON unit test) pass.

1 files changed, 216 insertions, 6 deletions

diff --git a/json.c b/json.c
index 42cfbc9a..cd9f85b4 100644
--- a/json.c
+++ b/json.c
@@ -63,7 +63,7 @@ PERMISSIONS
 #include <stdlib.h>
 #include <stdbool.h>
 #include <stdarg.h>
-#include <locale.h>
+#include <errno.h>
 #include <ctype.h>
 
 #include "gpsd_config.h"	/* for strlcpy() prototype */
@@ -148,6 +148,220 @@ static /*@null@*/ char *json_target_address(const struct json_attr_t *cursor,
     return targetaddr;
 }
 
+
+/*
+ * Berkeley implementation of strtod(), inlined to avoid locale problems
+ * with the decimal point.
+ */
+
+static int maxExponent = 511;	/* Largest possible base 10 exponent.  Any
+				 * exponent larger than this will already
+				 * produce underflow or overflow, so there's
+				 * no need to worry about additional digits.
+				 */
+static double powersOf10[] = {	/* Table giving binary powers of 10.  Entry */
+    10.,			/* is 10^2^i.  Used to convert decimal */
+    100.,			/* exponents into floating-point numbers. */
+    1.0e4,
+    1.0e8,
+    1.0e16,
+    1.0e32,
+    1.0e64,
+    1.0e128,
+    1.0e256
+};
+
+static double
+c_strtod(string, endPtr)
+    const char *string;		/* A decimal ASCII floating-point number,
+				 * optionally preceded by white space.
+				 * Must have form "-I.FE-X", where I is the
+				 * integer part of the mantissa, F is the
+				 * fractional part of the mantissa, and X
+				 * is the exponent.  Either of the signs
+				 * may be "+", "-", or omitted.  Either I
+				 * or F may be omitted, or both.  The decimal
+				 * point isn't necessary unless F is present.
+				 * The "E" may actually be an "e".  E and X
+				 * may both be omitted (but not just one).
+				 */
+    char **endPtr;		/* If non-NULL, store terminating character's
+				 * address here. */
+{
+    int sign, expSign = false;
+    double fraction, dblExp, *d;
+    register const char *p;
+    register int c;
+    int exp = 0;		/* Exponent read from "EX" field. */
+    int fracExp = 0;		/* Exponent that derives from the fractional
+				 * part.  Under normal circumstatnces, it is
+				 * the negative of the number of digits in F.
+				 * However, if I is very long, the last digits
+				 * of I get dropped (otherwise a long I with a
+				 * large negative exponent could cause an
+				 * unnecessary overflow on I alone).  In this
+				 * case, fracExp is incremented one for each
+				 * dropped digit. */
+    int mantSize;		/* Number of digits in mantissa. */
+    int decPt;			/* Number of mantissa digits BEFORE decimal
+				 * point. */
+    const char *pExp;		/* Temporarily holds location of exponent
+				 * in string. */
+
+    /*
+     * Strip off leading blanks and check for a sign.
+     */
+
+    p = string;
+    while (isspace(*p)) {
+	p += 1;
+    }
+    if (*p == '-') {
+	sign = true;
+	p += 1;
+    } else {
+	if (*p == '+') {
+	    p += 1;
+	}
+	sign = false;
+    }
+
+    /*
+     * Count the number of digits in the mantissa (including the decimal
+     * point), and also locate the decimal point.
+     */
+
+    decPt = -1;
+    for (mantSize = 0; ; mantSize += 1)
+    {
+	c = *p;
+	if (!isdigit(c)) {
+	    if ((c != '.') || (decPt >= 0)) {
+		break;
+	    }
+	    decPt = mantSize;
+	}
+	p += 1;
+    }
+
+    /*
+     * Now suck up the digits in the mantissa.  Use two integers to
+     * collect 9 digits each (this is faster than using floating-point).
+     * If the mantissa has more than 18 digits, ignore the extras, since
+     * they can't affect the value anyway.
+     */
+    
+    pExp  = p;
+    p -= mantSize;
+    if (decPt < 0) {
+	decPt = mantSize;
+    } else {
+	mantSize -= 1;			/* One of the digits was the point. */
+    }
+    if (mantSize > 18) {
+	fracExp = decPt - 18;
+	mantSize = 18;
+    } else {
+	fracExp = decPt - mantSize;
+    }
+    if (mantSize == 0) {
+	fraction = 0.0;
+	p = string;
+	goto done;
+    } else {
+	int frac1, frac2;
+	frac1 = 0;
+	for ( ; mantSize > 9; mantSize -= 1)
+	{
+	    c = *p;
+	    p += 1;
+	    if (c == '.') {
+		c = *p;
+		p += 1;
+	    }
+	    frac1 = 10*frac1 + (c - '0');
+	}
+	frac2 = 0;
+	for (; mantSize > 0; mantSize -= 1)
+	{
+	    c = *p;
+	    p += 1;
+	    if (c == '.') {
+		c = *p;
+		p += 1;
+	    }
+	    frac2 = 10*frac2 + (c - '0');
+	}
+	fraction = (1.0e9 * frac1) + frac2;
+    }
+
+    /*
+     * Skim off the exponent.
+     */
+
+    p = pExp;
+    if ((*p == 'E') || (*p == 'e')) {
+	p += 1;
+	if (*p == '-') {
+	    expSign = true;
+	    p += 1;
+	} else {
+	    if (*p == '+') {
+		p += 1;
+	    }
+	    expSign = false;
+	}
+	while (isdigit(*p)) {
+	    exp = exp * 10 + (*p - '0');
+	    p += 1;
+	}
+    }
+    if (expSign) {
+	exp = fracExp - exp;
+    } else {
+	exp = fracExp + exp;
+    }
+
+    /*
+     * Generate a floating-point number that represents the exponent.
+     * Do this by processing the exponent one bit at a time to combine
+     * many powers of 2 of 10. Then combine the exponent with the
+     * fraction.
+     */
+    
+    if (exp < 0) {
+	expSign = true;
+	exp = -exp;
+    } else {
+	expSign = false;
+    }
+    if (exp > maxExponent) {
+	exp = maxExponent;
+	errno = ERANGE;
+    }
+    dblExp = 1.0;
+    for (d = powersOf10; exp != 0; exp >>= 1, d += 1) {
+	if (exp & 01) {
+	    dblExp *= *d;
+	}
+    }
+    if (expSign) {
+	fraction /= dblExp;
+    } else {
+	fraction *= dblExp;
+    }
+
+done:
+    if (endPtr != NULL) {
+	*endPtr = (char *) p;
+    }
+
+    if (sign) {
+	return -fraction;
+    }
+    return fraction;
+}
+
 /*@-immediatetrans -dependenttrans +usereleased +compdef@*/
 
 static int json_internal_read_object(const char *cp,
@@ -445,7 +659,7 @@ static int json_internal_read_object(const char *cp,
 		    *((double *)lptr) = iso8601_to_unix(valbuf);
 		    break;
 		case t_real:
-		    *((double *)lptr) = atof(valbuf);
+		    *((double *)lptr) = c_strtod(valbuf, (char **)NULL);
 		    break;
 		case t_string:
 		    if (parent != NULL
@@ -604,14 +818,10 @@ int json_read_array(const char *cp, const struct json_array_t *arr,
 int json_read_object(const char *cp, const struct json_attr_t *attrs,
 		     /*@null@*/ const char **end)
 {
-    char *savedlocale = setlocale(LC_ALL, NULL);
     int st;
 
-    /* temporary locale setting is required wherever ',' is the decimal point */
-    (void)setlocale(LC_ALL, "C");
     json_debug_trace((1, "json_read_object() sees '%s'\n", cp));
     st = json_internal_read_object(cp, attrs, NULL, 0, end);
-    (void)setlocale(LC_ALL, savedlocale);
     return st;
 }