Support locales which use comma decimal separators

Some locales (cs_CZ, de_DE,..) use a comma as their decimal separator.
This causes CJSON to generate incorrect JSON (Eg, [10,1]), and fail when
parsing some valid JSON (Eg, [10,"test"]).

Added USE_POSIX_LOCALE #define which harnesses the thread-safe
POSIX.1-2008 locale support (newlocale(), uselocale(), freelocale())
to temporarily use the POSIX locale during JSON conversion.

Some older POSIX operating systems with xlocale.h (MacOSX) are also
supported.

1 files changed, 51 insertions, 0 deletions

diff --git a/lua_cjson.c b/lua_cjson.c
index f765883..151fa39 100644
--- a/lua_cjson.c
+++ b/lua_cjson.c
@@ -44,7 +44,30 @@
 
 #include "strbuf.h"
 
+#ifdef USE_POSIX_LOCALE
+/* Reset locale to POSIX for strtod() / sprintf().
+ * Some locales use comma as a decimal separator. This breaks JSON. */
+
+/* unistd.h defines _POSIX_VERSION */
+#include <unistd.h>
+#if _POSIX_VERSION >= 200809L
+/* POSIX.1-2008 adds threadsafe locale support */
+#include <locale.h>
+#elif defined(_POSIX_VERSION)
+/* Some pre-POSIX.1-2008 operating systems use xlocale.h instead */
+#include <xlocale.h>
+#else
+#error Missing _POSIX_VERSION define
+#endif
+#define LOCALE_SET_POSIX(x) (x)->saved_locale = uselocale((x)->posix_locale)
+#define LOCALE_RESTORE(x)   uselocale((x)->saved_locale)
+#else
+#define LOCALE_SET_POSIX(x) do { } while(0)
+#define LOCALE_RESTORE(x)   do { } while(0)
+#endif
+
 #ifdef MISSING_ISINF
+/* Some Solaris platforms are missing isinf(). Define here. */
 #define isinf(x) (!isnan(x) && isnan((x) - (x)))
 #endif
 
@@ -99,6 +122,10 @@ typedef struct {
     char *char2escape[256]; /* Encoding */
 #endif
     strbuf_t encode_buf;
+#if USE_POSIX_LOCALE
+    locale_t saved_locale;
+    locale_t posix_locale;
+#endif
     char number_fmt[8];     /* "%.XXg\0" */
     int current_depth;
 
@@ -342,6 +369,10 @@ static int json_destroy_config(lua_State *l)
     json_config_t *cfg;
 
     cfg = lua_touserdata(l, 1);
+#ifdef USE_POSIX_LOCALE
+    if (cfg->posix_locale)
+        freelocale(cfg->posix_locale);
+#endif
     if (cfg)
         strbuf_free(&cfg->encode_buf);
     cfg = NULL;
@@ -363,6 +394,13 @@ static void json_create_config(lua_State *l)
     lua_setmetatable(l, -2);
 
     strbuf_init(&cfg->encode_buf, 0);
+#if USE_POSIX_LOCALE
+    cfg->saved_locale = NULL;
+    /* Must not lua_error() before cfg->posix_locale has been initialised */
+    cfg->posix_locale = newlocale(LC_ALL_MASK, "C", NULL);
+    if (!cfg->posix_locale)
+        luaL_error(l, "Failed to create POSIX locale for JSON");
+#endif
 
     cfg->encode_sparse_convert = DEFAULT_SPARSE_CONVERT;
     cfg->encode_sparse_ratio = DEFAULT_SPARSE_RATIO;
@@ -452,6 +490,7 @@ static void json_encode_exception(lua_State *l, json_config_t *cfg, int lindex,
 {
     if (!cfg->encode_keep_buffer)
         strbuf_free(&cfg->encode_buf);
+    LOCALE_RESTORE(cfg);
     luaL_error(l, "Cannot serialise %s: %s",
                   lua_typename(l, lua_type(l, lindex)), reason);
 }
@@ -542,6 +581,7 @@ static void json_encode_descend(lua_State *l, json_config_t *cfg)
     if (cfg->current_depth > cfg->encode_max_depth) {
         if (!cfg->encode_keep_buffer)
             strbuf_free(&cfg->encode_buf);
+        LOCALE_RESTORE(cfg);
         luaL_error(l, "Cannot serialise, excessive nesting (%d)",
                    cfg->current_depth);
     }
@@ -701,9 +741,13 @@ static int json_encode(lua_State *l)
     else
         strbuf_init(&cfg->encode_buf, 0);
 
+    LOCALE_SET_POSIX(cfg);
+
     json_append_data(l, cfg, &cfg->encode_buf);
     json = strbuf_string(&cfg->encode_buf, &len);
 
+    LOCALE_RESTORE(cfg);
+
     lua_pushlstring(l, json, len);
 
     if (!cfg->encode_keep_buffer)
@@ -1084,6 +1128,8 @@ static void json_throw_parse_error(lua_State *l, json_parse_t *json,
     else
         found = json_token_type_name[token->type];
 
+    LOCALE_RESTORE(json->cfg);
+
     /* Note: token->index is 0 based, display starting from 1 */
     luaL_error(l, "Expected %s but found %s at character %d",
                exp, found, token->index + 1);
@@ -1095,6 +1141,7 @@ static void json_decode_checkstack(lua_State *l, json_parse_t *json, int n)
         return;
 
     strbuf_free(json->tmp);
+    LOCALE_RESTORE(json->cfg);
     luaL_error(l, "Too many nested data structures");
 }
 
@@ -1224,6 +1271,8 @@ static void lua_json_decode(lua_State *l, const char *json_text, int json_len)
      * string must be smaller than the entire json string */
     json.tmp = strbuf_new(json_len);
 
+    LOCALE_SET_POSIX(json.cfg);
+
     json_next_token(&json, &token);
     json_process_value(l, &json, &token);
 
@@ -1233,6 +1282,8 @@ static void lua_json_decode(lua_State *l, const char *json_text, int json_len)
     if (token.type != T_END)
         json_throw_parse_error(l, &json, "the end", &token);
 
+    LOCALE_RESTORE(json.cfg);
+
     strbuf_free(json.tmp);
 }