Correct regexp matching of raw bytes

Make regexp matching of raw bytes work in all combination of unibyte
and multibyte patterns and targets, as exact strings and in character
alternatives (bug#3687).

* src/regex-emacs.c (analyze_first):
Include raw byte in fastmap when pattern is a multibyte exact string.
Include leading byte in fastmap for raw bytes in character alternatives.
(re_match_2_internal):
Decrement the byte count by the number of bytes in the pattern character,
not 1.
* test/src/regex-emacs-tests.el (regexp-unibyte-unibyte)
(regexp-multibyte-unibyte, regexp-unibyte-mutibyte)
(regexp-multibyte-multibyte): New tests.

2 files changed, 140 insertions, 4 deletions

diff --git a/src/regex-emacs.c b/src/regex-emacs.c
index c353a78fb4f..5887eaa30c7 100644
--- a/src/regex-emacs.c
+++ b/src/regex-emacs.c
@@ -2794,6 +2794,7 @@ static int
 analyze_first (re_char *p, re_char *pend, char *fastmap, bool multibyte)
 {
   int j, k;
+  int nbits;
   bool not;
 
   /* If all elements for base leading-codes in fastmap is set, this
@@ -2854,7 +2855,14 @@ analyze_first (re_char *p, re_char *pend, char *fastmap, bool multibyte)
                  each byte is a character.  Thus, this works in both
                  cases. */
               fastmap[p[1]] = 1;
-              if (! multibyte)
+              if (multibyte)
+                {
+                  /* Cover the case of matching a raw char in a
+                     multibyte regexp against unibyte.  */
+                  if (CHAR_BYTE8_HEAD_P (p[1]))
+                    fastmap[CHAR_TO_BYTE8 (STRING_CHAR (p + 1))] = 1;
+                }
+              else
                 {
                   /* For the case of matching this unibyte regex
                      against multibyte, we must set a leading code of
@@ -2886,11 +2894,18 @@ analyze_first (re_char *p, re_char *pend, char *fastmap, bool multibyte)
         case charset:
           if (!fastmap) break;
           not = (re_opcode_t) *(p - 1) == charset_not;
-          for (j = CHARSET_BITMAP_SIZE (&p[-1]) * BYTEWIDTH - 1, p++;
-               j >= 0; j--)
+          nbits = CHARSET_BITMAP_SIZE (&p[-1]) * BYTEWIDTH;
+          p++;
+          for (j = 0; j < nbits; j++)
             if (!!(p[j / BYTEWIDTH] & (1 << (j % BYTEWIDTH))) ^ not)
               fastmap[j] = 1;
 
+          /* To match raw bytes (in the 80..ff range) against multibyte
+             strings, add their leading bytes to the fastmap.  */
+          for (j = 0x80; j < nbits; j++)
+            if (!!(p[j / BYTEWIDTH] & (1 << (j % BYTEWIDTH))) ^ not)
+              fastmap[CHAR_LEADING_CODE (BYTE8_TO_CHAR (j))] = 1;
+
           if (/* Any leading code can possibly start a character
                  which doesn't match the specified set of characters.  */
               not
@@ -4251,8 +4266,9 @@ re_match_2_internal (struct re_pattern_buffer *bufp,
                   }
                 p += pat_charlen;
                 d++;
+                mcnt -= pat_charlen;
               }
-            while (--mcnt);
+            while (mcnt > 0);
 
           break;
 
diff --git a/test/src/regex-emacs-tests.el b/test/src/regex-emacs-tests.el
index 0ae50c94d4c..50ed3e870a5 100644
--- a/test/src/regex-emacs-tests.el
+++ b/test/src/regex-emacs-tests.el
@@ -683,4 +683,124 @@ This evaluates the TESTS test cases from glibc."
   (should-not (string-match "\\`x\\{65535\\}" (make-string 65534 ?x)))
   (should-error (string-match "\\`x\\{65536\\}" "X") :type 'invalid-regexp))
 
+(ert-deftest regexp-unibyte-unibyte ()
+  "Test matching a unibyte regexp against a unibyte string."
+  ;; Sanity check
+  (should-not (multibyte-string-p "ab"))
+  (should-not (multibyte-string-p "\xff"))
+  ;; ASCII
+  (should (string-match "a[b]" "ab"))
+  ;; Raw
+  (should (string-match "\xf1" "\xf1"))
+  (should-not (string-match "\xf1" "\xc1\xb1"))
+  ;; Raw, char alt
+  (should (string-match "[\xf1]" "\xf1"))
+  (should-not (string-match "[\xf1]" "\xc1\xb1"))
+  ;; Raw range
+  (should (string-match "[\x82-\xd3]" "\xbb"))
+  (should-not (string-match "[\x82-\xd3]" "a"))
+  (should-not (string-match "[\x82-\xd3]" "\x81"))
+  (should-not (string-match "[\x82-\xd3]" "\xd4"))
+  ;; ASCII-raw range
+  (should (string-match "[f-\xd3]" "q"))
+  (should (string-match "[f-\xd3]" "\xbb"))
+  (should-not (string-match "[f-\xd3]" "e"))
+  (should-not (string-match "[f-\xd3]" "\xd4")))
+
+(ert-deftest regexp-multibyte-multibyte ()
+  "Test matching a multibyte regexp against a multibyte string."
+  ;; Sanity check
+  (should (multibyte-string-p "åü"))
+  ;; ASCII
+  (should (string-match (string-to-multibyte "a[b]")
+                        (string-to-multibyte "ab")))
+  ;; Unicode
+  (should (string-match "å[ü]z" "åüz"))
+  (should-not (string-match "ü" (string-to-multibyte "\xc3\xbc")))
+  ;; Raw
+  (should (string-match (string-to-multibyte "\xf1")
+                        (string-to-multibyte "\xf1")))
+  (should-not (string-match (string-to-multibyte "\xf1")
+                            (string-to-multibyte "\xc1\xb1")))
+  (should-not (string-match (string-to-multibyte "\xc1\xb1")
+                            (string-to-multibyte "\xf1")))
+  ;; Raw, char alt
+  (should (string-match (string-to-multibyte "[\xf1]")
+                        (string-to-multibyte "\xf1")))
+  ;; Raw range
+  (should (string-match (string-to-multibyte "[\x82-\xd3]")
+                        (string-to-multibyte "\xbb")))
+  (should-not (string-match (string-to-multibyte "[\x82-\xd3]") "a"))
+  (should-not (string-match (string-to-multibyte "[\x82-\xd3]") "Å"))
+  (should-not (string-match (string-to-multibyte "[\x82-\xd3]") "ü"))
+  (should-not (string-match (string-to-multibyte "[\x82-\xd3]") "\x81"))
+  (should-not (string-match (string-to-multibyte "[\x82-\xd3]") "\xd4"))
+  ;; ASCII-raw range: should exclude U+0100..U+10FFFF
+  (should (string-match (string-to-multibyte "[f-\xd3]")
+                        (string-to-multibyte "q")))
+  (should (string-match (string-to-multibyte "[f-\xd3]")
+                        (string-to-multibyte "\xbb")))
+  (should-not (string-match (string-to-multibyte "[f-\xd3]") "e"))
+  (should-not (string-match (string-to-multibyte "[f-\xd3]") "Å"))
+  (should-not (string-match (string-to-multibyte "[f-\xd3]") "ü"))
+  (should-not (string-match (string-to-multibyte "[f-\xd3]") "\xd4"))
+  ;; Unicode-raw range: should be empty
+  (should-not (string-match "[å-\xd3]" "å"))
+  (should-not (string-match "[å-\xd3]" (string-to-multibyte "\xd3")))
+  (should-not (string-match "[å-\xd3]" (string-to-multibyte "\xbb")))
+  (should-not (string-match "[å-\xd3]" "ü"))
+  ;; No equivalence between raw bytes and latin-1
+  (should-not (string-match "å" (string-to-multibyte "\xe5")))
+  (should-not (string-match "[å]" (string-to-multibyte "\xe5")))
+  (should-not (string-match "\xe5" "å"))
+  (should-not (string-match "[\xe5]" "å")))
+
+(ert-deftest regexp-unibyte-multibyte ()
+  "Test matching a unibyte regexp against a multibyte string."
+  ;; ASCII
+  (should (string-match "a[b]" (string-to-multibyte "ab")))
+  ;; Unicode
+  (should (string-match "a.[^b]c" (string-to-multibyte "aåüc")))
+  ;; Raw
+  (should (string-match "\xf1" (string-to-multibyte "\xf1")))
+  (should-not (string-match "\xc1\xb1" (string-to-multibyte "\xf1")))
+  ;; Raw, char alt
+  (should (string-match "[\xf1]" (string-to-multibyte "\xf1")))
+  (should-not (string-match "[\xc1][\xb1]" (string-to-multibyte "\xf1")))
+  ;; ASCII-raw range: should exclude U+0100..U+10FFFF
+  (should (string-match "[f-\xd3]" (string-to-multibyte "q")))
+  (should (string-match "[f-\xd3]" (string-to-multibyte "\xbb")))
+  (should-not (string-match "[f-\xd3]" "e"))
+  (should-not (string-match "[f-\xd3]" "Å"))
+  (should-not (string-match "[f-\xd3]" "ü"))
+  (should-not (string-match "[f-\xd3]" "\xd4"))
+  ;; No equivalence between raw bytes and latin-1
+  (should-not (string-match "\xe5" "å"))
+  (should-not (string-match "[\xe5]" "å")))
+
+(ert-deftest regexp-multibyte-unibyte ()
+  "Test matching a multibyte regexp against a unibyte string."
+  ;; ASCII
+  (should (string-match (string-to-multibyte "a[b]") "ab"))
+  ;; Unicode
+  (should (string-match "a[^ü]c" "abc"))
+  (should-not (string-match "ü" "\xc3\xbc"))
+  ;; Raw
+  (should (string-match (string-to-multibyte "\xf1") "\xf1"))
+  (should-not (string-match (string-to-multibyte "\xf1") "\xc1\xb1"))
+  ;; Raw, char alt
+  (should (string-match (string-to-multibyte "[\xf1]") "\xf1"))
+  (should-not (string-match (string-to-multibyte "[\xf1]") "\xc1\xb1"))
+  ;; ASCII-raw range: should exclude U+0100..U+10FFFF
+  (should (string-match (string-to-multibyte "[f-\xd3]") "q"))
+  (should (string-match (string-to-multibyte "[f-\xd3]") "\xbb"))
+  (should-not (string-match (string-to-multibyte "[f-\xd3]") "e"))
+  (should-not (string-match (string-to-multibyte "[f-\xd3]") "\xd4"))
+  ;; Unicode-raw range: should be empty
+  (should-not (string-match "[å-\xd3]" "\xd3"))
+  (should-not (string-match "[å-\xd3]" "\xbb"))
+  ;; No equivalence between raw bytes and latin-1
+  (should-not (string-match "å" "\xe5"))
+  (should-not (string-match "[å]" "\xe5")))
+
 ;;; regex-emacs-tests.el ends here