ruby/SOURCES/rubygem-strscan-1.0.2-Accept-String-as-a-pattern.patch

From e56ac27d19cc3acdf6c1cb13b14224c43df5f5f6 Mon Sep 17 00:00:00 2001
From: Kouhei Sutou <kou@clear-code.com>
Date: Thu, 4 Apr 2019 17:52:50 +0900
Subject: [PATCH] Accept String as a pattern

It's only for head only match case such as StringScanner#scan.

If we use a String as a pattern, we can improve match performance.
Here is a result of the including benchmark. It shows String as a
pattern is 1.25x faster than Regexp as a pattern.

    % rake benchmark
    /tmp/local/bin/ruby -S benchmark-driver benchmark/scan.yaml
    Warming up --------------------------------------
                  regexp    12.094M i/s -     12.242M times in 1.012250s (82.69ns/i, 277clocks/i)
                  string    14.653M i/s -     14.889M times in 1.016124s (68.25ns/i, 252clocks/i)
    Calculating -------------------------------------
                  regexp    14.713M i/s -     36.281M times in 2.465970s (67.97ns/i, 254clocks/i)
                  string    18.422M i/s -     43.959M times in 2.386255s (54.28ns/i, 201clocks/i)

    Comparison:
                  string:  18421631.8 i/s
                  regexp:  14712660.7 i/s - 1.25x  slower

====
Backport https://github.com/ruby/strscan/pull/4 for strscan.

REXML fixes for CVE-2024-35716 depend on this feature.
---
 ext/strscan/strscan.c              | 92 +++++++++++++++++++-----------
 test/strscan/test_stringscanner.rb | 45 ++++++++++++++-
 2 files changed, 100 insertions(+), 37 deletions(-)

diff --git a/ext/strscan/strscan.c b/ext/strscan/strscan.c
index d6168a0d4f..43319b672e 100644
--- a/ext/strscan/strscan.c
+++ b/ext/strscan/strscan.c
@@ -447,15 +447,18 @@ strscan_set_pos(VALUE self, VALUE v)
 }
 
 static VALUE
-strscan_do_scan(VALUE self, VALUE regex, int succptr, int getstr, int headonly)
+strscan_do_scan(VALUE self, VALUE pattern, int succptr, int getstr, int headonly)
 {
-    regex_t *rb_reg_prepare_re(VALUE re, VALUE str);
     struct strscanner *p;
-    regex_t *re;
-    long ret;
-    int tmpreg;
 
-    Check_Type(regex, T_REGEXP);
+    if (headonly) {
+        if (!RB_TYPE_P(pattern, T_REGEXP)) {
+            StringValue(pattern);
+        }
+    }
+    else {
+        Check_Type(pattern, T_REGEXP);
+    }
     GET_SCANNER(self, p);
 
     CLEAR_MATCH_STATUS(p);
@@ -463,37 +466,55 @@ strscan_do_scan(VALUE self, VALUE regex, int succptr, int getstr, int headonly)
         return Qnil;
     }
 
-    p->regex = regex;
-    re = rb_reg_prepare_re(regex, p->str);
-    tmpreg = re != RREGEXP_PTR(regex);
-    if (!tmpreg) RREGEXP(regex)->usecnt++;
+    if (RB_TYPE_P(pattern, T_REGEXP)) {
+        regex_t *rb_reg_prepare_re(VALUE re, VALUE str);
+        regex_t *re;
+        long ret;
+        int tmpreg;
+
+        p->regex = pattern;
+        re = rb_reg_prepare_re(pattern, p->str);
+        tmpreg = re != RREGEXP_PTR(pattern);
+        if (!tmpreg) RREGEXP(pattern)->usecnt++;
+
+        if (headonly) {
+            ret = onig_match(re, (UChar* )CURPTR(p),
+                             (UChar* )(CURPTR(p) + S_RESTLEN(p)),
+                             (UChar* )CURPTR(p), &(p->regs), ONIG_OPTION_NONE);
+        }
+        else {
+            ret = onig_search(re,
+                              (UChar* )CURPTR(p), (UChar* )(CURPTR(p) + S_RESTLEN(p)),
+                              (UChar* )CURPTR(p), (UChar* )(CURPTR(p) + S_RESTLEN(p)),
+                              &(p->regs), ONIG_OPTION_NONE);
+        }
+        if (!tmpreg) RREGEXP(pattern)->usecnt--;
+        if (tmpreg) {
+            if (RREGEXP(pattern)->usecnt) {
+                onig_free(re);
+            }
+            else {
+                onig_free(RREGEXP_PTR(pattern));
+                RREGEXP_PTR(pattern) = re;
+            }
+        }
 
-    if (headonly) {
-        ret = onig_match(re, (UChar* )CURPTR(p),
-                         (UChar* )(CURPTR(p) + S_RESTLEN(p)),
-                         (UChar* )CURPTR(p), &(p->regs), ONIG_OPTION_NONE);
+        if (ret == -2) rb_raise(ScanError, "regexp buffer overflow");
+        if (ret < 0) {
+            /* not matched */
+            return Qnil;
+        }
     }
     else {
-        ret = onig_search(re,
-                          (UChar* )CURPTR(p), (UChar* )(CURPTR(p) + S_RESTLEN(p)),
-                          (UChar* )CURPTR(p), (UChar* )(CURPTR(p) + S_RESTLEN(p)),
-                          &(p->regs), ONIG_OPTION_NONE);
-    }
-    if (!tmpreg) RREGEXP(regex)->usecnt--;
-    if (tmpreg) {
-        if (RREGEXP(regex)->usecnt) {
-            onig_free(re);
+        rb_enc_check(p->str, pattern);
+        if (S_RESTLEN(p) < RSTRING_LEN(pattern)) {
+            return Qnil;
         }
-        else {
-            onig_free(RREGEXP_PTR(regex));
-            RREGEXP_PTR(regex) = re;
+        if (memcmp(CURPTR(p), RSTRING_PTR(pattern), RSTRING_LEN(pattern)) != 0) {
+            return Qnil;
         }
-    }
-
-    if (ret == -2) rb_raise(ScanError, "regexp buffer overflow");
-    if (ret < 0) {
-        /* not matched */
-        return Qnil;
+        onig_region_clear(&(p->regs));
+        onig_region_set(&(p->regs), 0, 0, RSTRING_LEN(pattern));
     }
 
     MATCHED(p);
@@ -520,7 +541,8 @@ strscan_do_scan(VALUE self, VALUE regex, int succptr, int getstr, int headonly)
  *   p s.scan(/\w+/)   # -> "test"
  *   p s.scan(/\w+/)   # -> nil
  *   p s.scan(/\s+/)   # -> " "
- *   p s.scan(/\w+/)   # -> "string"
+ *   p s.scan("str")   # -> "str"
+ *   p s.scan(/\w+/)   # -> "ing"
  *   p s.scan(/./)     # -> nil
  *
  */
@@ -539,6 +561,7 @@ strscan_scan(VALUE self, VALUE re)
  *   s = StringScanner.new('test string')
  *   p s.match?(/\w+/)   # -> 4
  *   p s.match?(/\w+/)   # -> 4
+ *   p s.match?("test")  # -> 4
  *   p s.match?(/\s+/)   # -> nil
  */
 static VALUE
@@ -560,7 +583,8 @@ strscan_match_p(VALUE self, VALUE re)
  *   p s.skip(/\w+/)   # -> 4
  *   p s.skip(/\w+/)   # -> nil
  *   p s.skip(/\s+/)   # -> 1
- *   p s.skip(/\w+/)   # -> 6
+ *   p s.skip("st")    # -> 2
+ *   p s.skip(/\w+/)   # -> 4
  *   p s.skip(/./)     # -> nil
  *
  */
diff --git a/test/strscan/test_stringscanner.rb b/test/strscan/test_stringscanner.rb
index 3423f9cfed..63b1ce1f9b 100644
--- a/test/strscan/test_stringscanner.rb
+++ b/test/strscan/test_stringscanner.rb
@@ -282,6 +282,22 @@ def test_scan
     assert_equal "", s.scan(//)
   end
 
+  def test_scan_string
+    s = StringScanner.new('stra strb strc')
+    assert_equal 'str', s.scan('str')
+    assert_equal 'str', s[0]
+    assert_equal 3, s.pos
+    assert_equal false, s.tainted?
+    assert_equal 'a ', s.scan('a ')
+
+    str = 'stra strb strc'.dup
+    str.taint
+    s = StringScanner.new(str, false)
+    matched = s.scan('str')
+    assert_equal 'str', matched
+    assert_equal true, matched.tainted?
+  end
+
   def test_skip
     s = StringScanner.new('stra strb strc', true)
     assert_equal 4, s.skip(/\w+/)
@@ -367,8 +383,10 @@ def test_matched
     assert_equal false, s.matched.tainted?
     s.scan(/\s+/)
     assert_equal ' ', s.matched
+    s.scan('st')
+    assert_equal 'st', s.matched
     s.scan(/\w+/)
-    assert_equal 'strb', s.matched
+    assert_equal 'rb', s.matched
     s.scan(/\s+/)
     assert_equal ' ', s.matched
     s.scan(/\w+/)
@@ -483,7 +501,7 @@ def test_pre_match
     s.skip(/\s/)
     assert_equal 'a', s.pre_match
     assert_equal false, s.pre_match.tainted?
-    s.scan(/\w/)
+    s.scan('b')
     assert_equal 'a ', s.pre_match
     s.scan_until(/c/)
     assert_equal 'a b ', s.pre_match
@@ -513,7 +531,7 @@ def test_post_match
     assert_equal ' b c d e', s.post_match
     s.skip(/\s/)
     assert_equal 'b c d e', s.post_match
-    s.scan(/\w/)
+    s.scan('b')
     assert_equal ' c d e', s.post_match
     s.scan_until(/c/)
     assert_equal ' d e', s.post_match
@@ -589,6 +607,20 @@ def test_encoding
     assert_equal(Encoding::EUC_JP, ss.scan(/./e).encoding)
   end
 
+  def test_encoding_string
+    str = "\xA1\xA2".dup.force_encoding("euc-jp")
+    ss = StringScanner.new(str)
+    assert_equal(str.dup, ss.scan(str.dup))
+  end
+
+  def test_invalid_encoding_string
+    str = "\xA1\xA2".dup.force_encoding("euc-jp")
+    ss = StringScanner.new(str)
+    assert_raise(Encoding::CompatibilityError) do
+      ss.scan(str.encode("UTF-8"))
+    end
+  end
+
   def test_generic_regexp
     ss = StringScanner.new("\xA1\xA2".dup.force_encoding("euc-jp"))
     t = ss.scan(/./)
@@ -643,6 +675,13 @@ def test_exist_p
     assert_equal(nil, s.exist?(/e/))
   end
 
+  def test_exist_p_string
+    s = StringScanner.new("test string")
+    assert_raise(TypeError) do
+      s.exist?(" ")
+    end
+  end
+
   def test_skip_until
     s = StringScanner.new("Foo Bar Baz")
     assert_equal(3, s.skip_until(/Foo/))