Make real number encoding and decoding work under all locales

The decimal point '.' is changed to locale's decimal point
before/after JSON conversion to make C standard library's
locale-specific string conversion functions work correctly.

All the tests now call setlocale(LC_ALL, "") on startup to use the
locale set in the environment.

Fixes GH-32.

configure.ac

@@ -14,6 +14,7 @@ AM_CONDITIONAL([GCC], [test x$GCC = xyes])
 # Checks for libraries.
 
 # Checks for header files.
+AC_CHECK_HEADERS([locale.h])
 
 # Checks for typedefs, structures, and compiler characteristics.
 AC_TYPE_INT32_T
@@ -34,6 +35,12 @@ esac
 AC_SUBST([json_inline])
 
 # Checks for library functions.
+AC_CHECK_FUNCS([setlocale localeconv])
+case "$ac_cv_header_locale_h$ac_cv_func_localeconv" in
+     yesyes) json_have_localeconv=1;;
+     *) json_have_localeconv=0;;
+esac
+AC_SUBST([json_have_localeconv])
 
 AC_CONFIG_FILES([
         jansson.pc

doc/conformance.rst

@@ -110,3 +110,25 @@ types, ``long double``, etc. Obviously, shorter types like ``short``,
 are implicitly handled via the ordinary C type coercion rules (subject
 to overflow semantics). Also, no support or hooks are provided for any
 supplemental "bignum" type add-on packages.
+
+
+Locale
+======
+
+Jansson works fine under any locale.
+
+However, if the host program is multithreaded and uses ``setlocale()``
+to switch the locale in one thread while Jansson is currently encoding
+or decoding JSON data in another thread, the result may be wrong or
+the program may even crash.
+
+Jansson uses locale specific functions for certain string conversions
+in the encoder and decoder, and then converts the locale specific
+values to/from the JSON representation. This fails if the locale
+changes between the string conversion and the locale-to-JSON
+conversion. This can only happen in multithreaded programs that use
+``setlocale()``, that switches the locale for all running threads, not
+only the thread that calls ``setlocale()``.
+
+If your program uses ``setlocale()`` as described above, consider
+using the thread-safe ``uselocale()`` instead.

src/Makefile.am

@@ -12,6 +12,7 @@ libjansson_la_SOURCES = \
 	pack_unpack.c \
 	strbuffer.c \
 	strbuffer.h \
+	strconv.c \
 	utf.c \
 	utf.h \
 	value.c

src/dump.c

@@ -196,26 +196,12 @@ static int do_dump(const json_t *json, size_t flags, int depth,
         {
             char buffer[MAX_REAL_STR_LENGTH];
             int size;
+            double value = json_real_value(json);
 
-            size = snprintf(buffer, MAX_REAL_STR_LENGTH, "%.17g",
-                            json_real_value(json));
-            if(size >= MAX_REAL_STR_LENGTH)
+            size = jsonp_dtostr(buffer, MAX_REAL_STR_LENGTH, value);
+            if(size < 0)
                 return -1;
 
-            /* Make sure there's a dot or 'e' in the output. Otherwise
-               a real is converted to an integer when decoding */
-            if(strchr(buffer, '.') == NULL &&
-               strchr(buffer, 'e') == NULL)
-            {
-                if(size + 2 >= MAX_REAL_STR_LENGTH) {
-                    /* No space to append ".0" */
-                    return -1;
-                }
-                buffer[size] = '.';
-                buffer[size + 1] = '0';
-                size += 2;
-            }
-
             return dump(buffer, size, data);
         }
 

src/jansson_config.h.in

@@ -31,4 +31,8 @@
    JSON_INTEGER_IS_LONG_LONG is defined to 1, otherwise to 0. */
 #define JSON_INTEGER_IS_LONG_LONG @json_have_long_long@
 
+/* If locale.h and localeconv() are available, define to 1,
+   otherwise to 0. */
+#define JSON_HAVE_LOCALECONV @json_have_localeconv@
+
 #endif

src/jansson_config.h.win32

@@ -31,4 +31,8 @@
    JSON_INTEGER_IS_LONG_LONG is defined to 1, otherwise to 0. */
 #define JSON_INTEGER_IS_LONG_LONG 1
 
+/* If locale.h and localeconv() are available, define to 1,
+   otherwise to 0. */
+#define JSON_HAVE_LOCALECONV 1
+
 #endif

src/jansson_private.h

@@ -11,6 +11,7 @@
 #include <stddef.h>
 #include "jansson.h"
 #include "hashtable.h"
+#include "strbuffer.h"
 
 #define container_of(ptr_, type_, member_)  \
     ((type_ *)((char *)ptr_ - offsetof(type_, member_)))
@@ -83,6 +84,10 @@ void jsonp_error_set(json_error_t *error, int line, int column,
 void jsonp_error_vset(json_error_t *error, int line, int column,
                       size_t position, const char *msg, va_list ap);
 
+/* Locale independent string<->double conversions */
+int jsonp_strtod(strbuffer_t *strbuffer, double *out);
+int jsonp_dtostr(char *buffer, size_t size, double value);
+
 /* Wrappers for custom memory functions */
 void* jsonp_malloc(size_t size);
 void jsonp_free(void *ptr);

src/load.c

@@ -524,12 +524,7 @@ static int lex_scan_number(lex_t *lex, int c, json_error_t *error)
 
     lex_unget_unsave(lex, c);
 
-    saved_text = strbuffer_value(&lex->saved_text);
-    errno = 0;
-    value = strtod(saved_text, &end);
-    assert(end == saved_text + lex->saved_text.length);
-
-    if(errno == ERANGE && value != 0) {
+    if(jsonp_strtod(&lex->saved_text, &value)) {
         error_set(error, lex, "real number overflow");
         goto out;
     }

src/strconv.c

@@ -0,0 +1,108 @@
+#include <assert.h>
+#include <errno.h>
+#include <stdio.h>
+#include <string.h>
+#include "jansson_private.h"
+#include "strbuffer.h"
+
+#if JSON_HAVE_LOCALECONV
+#include <locale.h>
+
+/*
+  - This code assumes that the decimal separator is exactly one
+    character.
+
+  - If setlocale() is called by another thread between the call to
+    localeconv() and the call to sprintf() or strtod(), the result may
+    be wrong. setlocale() is not thread-safe and should not be used
+    this way. Multi-threaded programs should use uselocale() instead.
+*/
+
+static void to_locale(strbuffer_t *strbuffer)
+{
+    const char *point;
+    char *pos;
+
+    point = localeconv()->decimal_point;
+    if(*point == '.') {
+        /* No conversion needed */
+        return;
+    }
+
+    pos = strstr(strbuffer->value, ".");
+    if(pos)
+        *pos = *point;
+}
+
+static void from_locale(char *buffer)
+{
+    const char *point;
+    char *pos;
+
+    point = localeconv()->decimal_point;
+    if(*point == '.') {
+        /* No conversion needed */
+        return;
+    }
+
+    pos = strstr(buffer, point);
+    if(pos)
+        *pos = '.';
+}
+#endif
+
+int jsonp_strtod(strbuffer_t *strbuffer, double *out)
+{
+    double value;
+    char *end;
+
+#if JSON_HAVE_LOCALECONV
+    to_locale(strbuffer);
+#endif
+
+    errno = 0;
+    value = strtod(strbuffer->value, &end);
+    assert(end == strbuffer->value + strbuffer->length);
+
+    if(errno == ERANGE && value != 0) {
+        /* Overflow */
+        return -1;
+    }
+
+    *out = value;
+    return 0;
+}
+
+int jsonp_dtostr(char *buffer, size_t size, double value)
+{
+    int ret;
+    size_t length;
+
+    ret = snprintf(buffer, size, "%.17g", value);
+    if(ret < 0)
+        return -1;
+
+    length = (size_t)ret;
+    if(length >= size)
+        return -1;
+
+#if JSON_HAVE_LOCALECONV
+    from_locale(buffer);
+#endif
+
+    /* Make sure there's a dot or 'e' in the output. Otherwise
+       a real is converted to an integer when decoding */
+    if(strchr(buffer, '.') == NULL &&
+       strchr(buffer, 'e') == NULL)
+    {
+        if(length + 2 >= size) {
+            /* No space to append ".0" */
+            return -1;
+        }
+        buffer[length] = '.';
+        buffer[length + 1] = '0';
+        length += 2;
+    }
+
+    return (int)length;
+}

test/bin/json_process.c

@@ -5,12 +5,20 @@
  * it under the terms of the MIT license. See LICENSE for details.
  */
 
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <ctype.h>
 #include <jansson.h>
 
+#if HAVE_LOCALE_H
+#include <locale.h>
+#endif
+
 static int getenv_int(const char *name)
 {
     char *value, *end;
@@ -55,6 +63,10 @@ int main(int argc, char *argv[])
     json_t *json;
     json_error_t error;
 
+#if HAVE_SETLOCALE
+    setlocale(LC_ALL, "");
+#endif
+
     if(argc != 1) {
         fprintf(stderr, "usage: %s\n", argv[0]);
         return 2;

test/suites/api/test_array.c

@@ -387,7 +387,7 @@ static void test_circular()
 }
 
 
-int main()
+static void run_tests()
 {
     test_misc();
     test_insert();
@@ -395,6 +395,4 @@ int main()
     test_clear();
     test_extend();
     test_circular();
-
-    return 0;
 }

test/suites/api/test_copy.c

@@ -307,7 +307,7 @@ static void test_deep_copy_object(void)
     json_decref(copy);
 }
 
-int main()
+static void run_tests()
 {
     test_copy_simple();
     test_deep_copy_simple();
@@ -315,5 +315,4 @@ int main()
     test_deep_copy_array();
     test_copy_object();
     test_deep_copy_object();
-    return 0;
 }

test/suites/api/test_dump.c

@@ -133,10 +133,9 @@ static void encode_other_than_array_or_object()
 
 }
 
-int main()
+static void run_tests()
 {
     encode_twice();
     circular_references();
     encode_other_than_array_or_object();
-    return 0;
 }

test/suites/api/test_dump_callback.c

@@ -26,7 +26,7 @@ static int my_writer(const char *buffer, size_t len, void *data) {
     return 0;
 }
 
-int main(void)
+static void run_tests()
 {
     struct my_sink s;
     json_t *json;
@@ -78,6 +78,4 @@ int main(void)
     json_decref(json);
     free(dumped_to_string);
     free(s.buf);
-    return EXIT_SUCCESS;
 }
-

test/suites/api/test_equal.c

@@ -180,11 +180,10 @@ static void test_equal_complex()
     /* TODO: There's no negative test case here */
 }
 
-int main()
+static void run_tests()
 {
     test_equal_simple();
     test_equal_array();
     test_equal_object();
     test_equal_complex();
-    return 0;
 }

test/suites/api/test_load.c

@@ -50,11 +50,9 @@ static void disable_eof_check()
     json_decref(json);
 }
 
-int main()
+static void run_tests()
 {
     file_not_found();
     reject_duplicates();
     disable_eof_check();
-
-    return 0;
 }

test/suites/api/test_loadb.c

@@ -9,7 +9,7 @@
 #include <string.h>
 #include "util.h"
 
-int main()
+static void run_tests()
 {
     json_t *json;
     json_error_t error;
@@ -33,6 +33,4 @@ int main()
     if(strcmp(error.text, "']' expected near end of file") != 0) {
         fail("json_loadb returned an invalid error message for an unclosed top-level array");
     }
-
-    return 0;
 }

test/suites/api/test_memory_funcs.c

@@ -75,10 +75,8 @@ static void test_secure_funcs(void)
     create_and_free_complex_object();
 }
 
-int main()
+static void run_tests()
 {
     test_simple();
     test_secure_funcs();
-
-    return 0;
 }

test/suites/api/test_number.c

@@ -8,7 +8,7 @@
 #include <jansson.h>
 #include "util.h"
 
-int main()
+static void run_tests()
 {
     json_t *integer, *real;
     int i;
@@ -39,6 +39,4 @@ int main()
 
     json_decref(integer);
     json_decref(real);
-
-    return 0;
 }

test/suites/api/test_object.c

@@ -437,7 +437,7 @@ static void test_preserve_order()
     json_decref(object);
 }
 
-int main()
+static void run_tests()
 {
     test_misc();
     test_clear();
@@ -446,6 +446,4 @@ int main()
     test_set_nocheck();
     test_iterators();
     test_preserve_order();
-
-    return 0;
 }

test/suites/api/test_pack.c

@@ -11,7 +11,7 @@
 #include <stdio.h>
 #include "util.h"
 
-int main()
+static void run_tests()
 {
     json_t *value;
     int i;
@@ -227,6 +227,4 @@ int main()
     if(json_pack_ex(&error, 0, "{s:s}", "foo", "\xff\xff"))
         fail("json_pack failed to catch invalid UTF-8 in a string");
     check_error("Invalid UTF-8 string", "<args>", 1, 4, 4);
-
-    return 0;
 }

test/suites/api/test_simple.c

@@ -10,7 +10,7 @@
 #include "util.h"
 
 /* Call the simple functions not covered by other tests of the public API */
-int main()
+static void run_tests()
 {
     json_t *value;
 
@@ -180,6 +180,4 @@ int main()
     json_incref(value);
     if(value->refcount != (size_t)-1)
       fail("refcounting null works incorrectly");
-
-    return 0;
 }

test/suites/api/test_unpack.c

@@ -11,7 +11,7 @@
 #include <stdio.h>
 #include "util.h"
 
-int main()
+static void run_tests()
 {
     json_t *j, *j2;
     int i1, i2, i3;
@@ -336,6 +336,4 @@ int main()
         fail("json_unpack nested array with strict validation failed");
     check_error("1 array item(s) left unpacked", "<validation>", 1, 5, 5);
     json_decref(j);
-
-    return 0;
 }

test/suites/api/util.h

@@ -8,8 +8,16 @@
 #ifndef UTIL_H
 #define UTIL_H
 
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
 #include <stdio.h>
 #include <stdlib.h>
+#if HAVE_LOCALE_H
+#include <locale.h>
+#endif
+
 #include <jansson.h>
 
 #define failhdr fprintf(stderr, "%s:%s:%d: ", __FILE__, __FUNCTION__, __LINE__)
@@ -52,4 +60,15 @@
         }                                                               \
     } while(0)
 
+
+static void run_tests();
+
+int main() {
+#ifdef HAVE_SETLOCALE
+    setlocale(LC_ALL, "");
+#endif
+    run_tests();
+    return 0;
+}
+
 #endif