shyouhei	2018-11-12 11:39:24 +0900 (Mon, 12 Nov 2018)

  New Revision: 65677

  https://svn.ruby-lang.org/cgi-bin/viewvc.cgi?view=revision&revision=65677

  Log:
    char is neither signed nor unsigned
    
    read_escaped_byte() returns values of range -1...256. -1 indicates
    error.  So the function basically expects char to be 0..255 range.
    There is no such guarantee. `char` is not always unsigned.  We
    need to explicitly declare chbuf to be unsigned char.

  Modified files:
    trunk/re.c
Index: re.c
===================================================================
--- re.c	(revision 65676)
+++ re.c	(revision 65677)
@@ -2389,7 +2389,8 @@ unescape_escaped_nonascii(const char **p https://github.com/ruby/ruby/blob/trunk/re.c#L2389
 {
     const char *p = *pp;
     int chmaxlen = rb_enc_mbmaxlen(enc);
-    char *chbuf = ALLOCA_N(char, chmaxlen);
+    unsigned char *area = ALLOCA_N(unsigned char, chmaxlen);
+    char *chbuf = (char *)area;
     int chlen = 0;
     int byte;
     int l;
@@ -2401,14 +2402,14 @@ unescape_escaped_nonascii(const char **p https://github.com/ruby/ruby/blob/trunk/re.c#L2402
         return -1;
     }
 
-    chbuf[chlen++] = byte;
+    area[chlen++] = byte;
     while (chlen < chmaxlen &&
            MBCLEN_NEEDMORE_P(rb_enc_precise_mbclen(chbuf, chbuf+chlen, enc))) {
         byte = read_escaped_byte(&p, end, err);
         if (byte == -1) {
             return -1;
         }
-        chbuf[chlen++] = byte;
+        area[chlen++] = byte;
     }
 
     l = rb_enc_precise_mbclen(chbuf, chbuf+chlen, enc);
@@ -2416,7 +2417,7 @@ unescape_escaped_nonascii(const char **p https://github.com/ruby/ruby/blob/trunk/re.c#L2417
         errcpy(err, "invalid multibyte escape");
         return -1;
     }
-    if (1 < chlen || (chbuf[0] & 0x80)) {
+    if (1 < chlen || (area[0] & 0x80)) {
         rb_str_buf_cat(buf, chbuf, chlen);
 
         if (*encp == 0)
@@ -2428,7 +2429,7 @@ unescape_escaped_nonascii(const char **p https://github.com/ruby/ruby/blob/trunk/re.c#L2429
     }
     else {
         char escbuf[5];
-        snprintf(escbuf, sizeof(escbuf), "\\x%02X", chbuf[0]&0xff);
+        snprintf(escbuf, sizeof(escbuf), "\\x%02X", area[0]&0xff);
         rb_str_buf_cat(buf, escbuf, 4);
     }
     *pp = p;

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