libsmartcols: Corrected JSON escaping

[thirdparty/util-linux.git] / include / carefulputc.h

diff --git a/include/carefulputc.h b/include/carefulputc.h
index 681e6666023b903cbe1ce5743d58c4828957c0af..688435ed5735c02b1c885ffcd1439e2e95e62c0d 100644 (file)
--- a/include/carefulputc.h
+++ b/include/carefulputc.h
@@ -26,6 +26,82 @@ static inline int fputc_careful(int c, FILE *fp, const char fail)
        return (ret < 0) ? EOF : 0;
 }
 
+/*
+ * Requirements enumerated via testing (V8, Firefox, IE11):
+ *
+ * var charsToEscape = [];
+ * for (var i = 0; i < 65535; i += 1) {
+ *     try {
+ *             JSON.parse('{"sample": "' + String.fromCodePoint(i) + '"}');
+ *     } catch (e) {
+ *             charsToEscape.push(i);
+ *     }
+ * }
+ */
+static inline void fputs_quoted_case_json(const char *data, FILE *out, int dir)
+{
+       const char *p;
+
+       fputc('"', out);
+       for (p = data; p && *p; p++) {
+
+               const unsigned char c = (unsigned char) *p;
+
+               /* From http://www.json.org
+                *
+                * The double-quote and backslashes would break out a string or
+                * init an escape sequence if not escaped.
+                *
+                * Note that single-quotes and forward slashes, while they're
+                * in the JSON spec, don't break double-quoted strings.
+                */
+               if (c == '"' || c == '\\') {
+                       fputc('\\', out);
+                       fputc(c, out);
+                       continue;
+               }
+
+               /* All non-control characters OK; do the case swap as required. */
+               if (c >= 0x20) {
+                       fputc(dir ==  1 ? toupper(c) :
+                             dir == -1 ? tolower(c) : *p, out);
+                       continue;
+               }
+
+               /* In addition, all chars under ' ' break Node's/V8/Chrome's, and
+                * Firefox's JSON.parse function
+                */
+               switch (c) {
+                       /* Handle short-hand cases to reduce output size.  C
+                        * has most of the same stuff here, so if there's an
+                        * "Escape for C" function somewhere in the STL, we
+                        * should probably be using it.
+                        */
+                       case '\b':
+                               fputs("\\b", out);
+                               break;
+                       case '\t':
+                               fputs("\\t", out);
+                               break;
+                       case '\n':
+                               fputs("\\n", out);
+                               break;
+                       case '\f':
+                               fputs("\\f", out);
+                               break;
+                       case '\r':
+                               fputs("\\r", out);
+                               break;
+                       default:
+                               /* Other assorted control characters */
+                               fprintf(out, "\\u00%02x", c);
+                               break;
+               }
+       }
+       fputc('"', out);
+}
+
+
 static inline void fputs_quoted_case(const char *data, FILE *out, int dir)
 {
        const char *p;
@@ -52,6 +128,10 @@ static inline void fputs_quoted_case(const char *data, FILE *out, int dir)
 #define fputs_quoted_upper(_d, _o)     fputs_quoted_case(_d, _o, 1)
 #define fputs_quoted_lower(_d, _o)     fputs_quoted_case(_d, _o, -1)
 
+#define fputs_quoted_json(_d, _o)       fputs_quoted_case_json(_d, _o, 0)
+#define fputs_quoted_json_upper(_d, _o) fputs_quoted_case_json(_d, _o, 1)
+#define fputs_quoted_json_lower(_d, _o) fputs_quoted_case_json(_d, _o, -1)
+
 static inline void fputs_nonblank(const char *data, FILE *out)
 {
        const char *p;