Thursday, May 26, 2011

Re: [BUG] 'non-empty string' >? '' returns false on amd64 arch

diff --git a/src/mbyte.c b/src/mbyte.c
index ce0c897..7ae7e78 100644
--- a/src/mbyte.c
+++ b/src/mbyte.c
@@ -1701,6 +1701,70 @@ utf_ptr2char(p)
}

/*
+ * Converts a UTF-8 byte sequence to a wide character.
+ * String is assumed to be terminated by NUL or after n bytes,
+ * whichever comes first.
+ * The function is safe in the sense that it never accesses
+ * memory beyond the first n bytes of s.
+ *
+ * On success, returns decoded codepoint, advances s to
+ * the beginning of next character and decreases n accordingly.
+ *
+ * If end of string was reached, returns 0 and, if n > 0,
+ * advances s past NUL byte.
+ *
+ * If byte sequence is illegal or incomplete, returns -1 and
+ * does not advance s.
+ */
+ static int
+utf_safe_read_char(s, n)
+ char_u **s;
+ size_t *n;
+{
+ int c, k;
+
+ if (*n == 0)
+ {
+ /* end of buffer */
+ return 0;
+ }
+
+ k = utf8len_tab_zero[**s];
+
+ if (k == 1)
+ {
+ /* ASCII character or NUL */
+ (*n)--;
+ return *(*s)++;
+ }
+
+ if (k <= *n)
+ {
+ /* We have a multibyte sequence and it isn't truncated by buffer
+ * limits so utf_ptr2char() is safe to use. Or the first byte is
+ * illegal (k=0), and it's also safe to use utf_ptr2char(). */
+
+ c = utf_ptr2char(*s);
+
+ /* On failure, utf_ptr2char() returns the first byte, so here we
+ * check equality with the first byte. The only non-ASCII character
+ * which equals the first byte of its own UTF-8 representation is
+ * U+00C3 (UTF-8: 0xC3 0x83), so need to check that special case too.
+ * It's safe even if n=1, else we would have k=2 > n. */
+ if (c != (int)(**s) || (c == 0xC3 && (*s)[1] == 0x83))
+ {
+ /* byte sequence was successfully decoded */
+ *s += k;
+ *n -= k;
+ return c;
+ }
+ }
+
+ /* byte sequence is incomplete or illegal */
+ return -1;
+}
+
+/*
* Get character at **pp and advance *pp to the next character.
* Note: composing characters are skipped!
*/
@@ -3079,6 +3143,80 @@ utf_isupper(a)
return (utf_tolower(a) != a);
}

+ static int
+utf_strnicmp(s1, s2, n1, n2)
+ char_u *s1, *s2;
+ size_t n1, n2;
+{
+ int c1, c2, cdiff;
+ char_u buffer[6];
+
+ for (;;)
+ {
+ c1 = utf_safe_read_char(&s1, &n1);
+ c2 = utf_safe_read_char(&s2, &n2);
+
+ if (c1 <= 0 || c2 <= 0)
+ break;
+
+ if (c1 == c2)
+ continue;
+
+ cdiff = utf_fold(c1) - utf_fold(c2);
+ if (cdiff != 0)
+ return cdiff;
+ }
+
+ /* some string ended or has an incomplete/illegal character sequence */
+
+ if (c1 == 0 || c2 == 0)
+ {
+ /* some string ended. shorter string is smaller */
+ if (c1 == 0 && c2 == 0)
+ return 0;
+ return c1 == 0 ? -1 : 1;
+ }
+
+ /* Continue with bytewise comparison to produce some result that
+ * would make comparison operations involving this function transitive.
+ *
+ * If only one string had an error, comparison should be made with
+ * folded version of the other string. In this case it is enough
+ * to fold just one character to determine the result of comparison. */
+
+ if (c1 != -1 && c2 == -1)
+ {
+ n1 = utf_char2bytes(utf_fold(c1), buffer);
+ s1 = buffer;
+ }
+ else if (c2 != -1 && c1 == -1)
+ {
+ n2 = utf_char2bytes(utf_fold(c2), buffer);
+ s2 = buffer;
+ }
+
+ while (n1 > 0 && n2 > 0 && *s1 != NUL && *s2 != NUL)
+ {
+ cdiff = (int)(*s1) - (int)(*s2);
+ if (cdiff != 0)
+ return cdiff;
+
+ s1++;
+ s2++;
+ n1--;
+ n2--;
+ }
+
+ if (n1 > 0 && *s1 == NUL)
+ n1 = 0;
+ if (n2 > 0 && *s2 == NUL)
+ n2 = 0;
+
+ if (n1 == 0 && n2 == 0)
+ return 0;
+ return n1 == 0 ? -1 : 1;
+}
+
/*
* Version of strnicmp() that handles multi-byte characters.
* Needed for Big5, Sjift-JIS and UTF-8 encoding. Other DBCS encodings can
@@ -3097,44 +3235,17 @@ mb_strnicmp(s1, s2, nn)
int incomplete = FALSE;
int n = (int)nn;

- for (i = 0; i < n; i += l)
+ if (enc_utf8)
{
- if (s1[i] == NUL && s2[i] == NUL) /* both strings end */
- return 0;
- if (enc_utf8)
- {
- l = utf_byte2len(s1[i]);
- if (l > n - i)
- {
- l = n - i; /* incomplete character */
- incomplete = TRUE;
- }
- /* Check directly first, it's faster. */
- for (j = 0; j < l; ++j)
- {
- if (s1[i + j] != s2[i + j])
- break;
- if (s1[i + j] == 0)
- /* Both stings have the same bytes but are incomplete or
- * have illegal bytes, accept them as equal. */
- l = j;
- }
- if (j < l)
- {
- /* If one of the two characters is incomplete return -1. */
- if (incomplete || i + utf_byte2len(s2[i]) > n)
- return -1;
- /* Don't case-fold illegal bytes or truncated characters. */
- if (utf_ptr2len(s1 + i) < l || utf_ptr2len(s2 + i) < l)
- return -1;
- cdiff = utf_fold(utf_ptr2char(s1 + i))
- - utf_fold(utf_ptr2char(s2 + i));
- if (cdiff != 0)
- return cdiff;
- }
- }
- else
- {
+ return utf_strnicmp(s1, s2, nn, nn);
+ }
+ else
+ {
+ for (i = 0; i < n; i += l)
+ {
+ if (s1[i] == NUL && s2[i] == NUL) /* both strings end */
+ return 0;
+
l = (*mb_ptr2len)(s1 + i);
if (l <= 1)
{
diff --git a/src/testdir/testXX.in b/src/testdir/testXX.in
new file mode 100644
index 0000000..63a81e7
--- /dev/null
+++ b/src/testdir/testXX.in
@@ -0,0 +1,93 @@
+Tests for case-insensitive UTF-8 comparisons (utf_strnicmp() in mbyte.c)
+
+STARTTEST
+:so small.vim
+:if !has("multi_byte")
+: e! test.ok
+: w! test.out
+: qa!
+:endif
+:set enc=utf8
+ggdG
+:
+:function! Ch(a, op, b, expected)
+: if eval(printf('"%s" %s "%s"', a:a, a:op, a:b)) != a:expected
+: call append(line('$'), printf('"%s" %s "%s" should return %d', a:a, a:op, a:b, a:expected))
+: else
+: let b:passed += 1
+: endif
+:endfunction
+:
+:function! Chk(a, b, result)
+: if a:result == 0
+: call Ch(a:a, '==?', a:b, 1)
+: call Ch(a:a, '!=?', a:b, 0)
+: call Ch(a:a, '<=?', a:b, 1)
+: call Ch(a:a, '>=?', a:b, 1)
+: call Ch(a:a, '<?', a:b, 0)
+: call Ch(a:a, '>?', a:b, 0)
+: elseif a:result > 0
+: call Ch(a:a, '==?', a:b, 0)
+: call Ch(a:a, '!=?', a:b, 1)
+: call Ch(a:a, '<=?', a:b, 0)
+: call Ch(a:a, '>=?', a:b, 1)
+: call Ch(a:a, '<?', a:b, 0)
+: call Ch(a:a, '>?', a:b, 1)
+: else
+: call Ch(a:a, '==?', a:b, 0)
+: call Ch(a:a, '!=?', a:b, 1)
+: call Ch(a:a, '<=?', a:b, 1)
+: call Ch(a:a, '>=?', a:b, 0)
+: call Ch(a:a, '<?', a:b, 1)
+: call Ch(a:a, '>?', a:b, 0)
+: endif
+:endfunction
+:
+:function! Check(a, b, result)
+: call Chk(a:a, a:b, a:result)
+: call Chk(a:b, a:a, -a:result)
+:endfunction
+:
+:function! LT(a, b)
+: call Check(a:a, a:b, -1)
+:endfunction
+:
+:function! GT(a, b)
+: call Check(a:a, a:b, 1)
+:endfunction
+:
+:function! EQ(a, b)
+: call Check(a:a, a:b, 0)
+:endfunction
+:
+:let b:passed=0
+:call EQ('', '')
+:call LT('', 'a')
+:call EQ('abc', 'abc')
+:call EQ('Abc', 'abC')
+:call LT('ab', 'abc')
+:call LT('AB', 'abc')
+:call LT('ab', 'aBc')
+:call EQ('\xd0\xb9\xd1\x86\xd1\x83\xd0\xba\xd0\xb5\xd0\xbd', '\xd0\xb9\xd0\xa6\xd0\xa3\xd0\xba\xd0\x95\xd0\xbd')
+:call LT('\xd0\xb9\xd1\x86\xd1\x83\xd0\xba\xd0\xb5\xd0\xbd', '\xd0\xaf\xd1\x86\xd1\x83\xd0\xba\xd0\xb5\xd0\xbd')
+:call EQ('\xe2\x84\xaa', 'k')
+:call LT('\xe2\x84\xaa', 'kkkkkk')
+:call EQ('\xe2\x84\xaa\xe2\x84\xaa\xe2\x84\xaa', 'kkk')
+:call LT('kk', '\xe2\x84\xaa\xe2\x84\xaa\xe2\x84\xaa')
+:call EQ('\xe2\x84\xaa\xe2\x84\xa6k\xe2\x84\xaak\xcf\x89', 'k\xcf\x89\xe2\x84\xaakk\xe2\x84\xa6')
+:call EQ('Abc\x80', 'AbC\x80')
+:call LT('Abc\x80', 'AbC\x81')
+:call LT('Abc', 'AbC\x80')
+:call LT('abc\x80DEF', 'abc\x80def') " case folding stops at the first bad character
+:call LT('\xc3XYZ', '\xc3xyz')
+:call EQ('\xef\xbc\xba', '\xef\xbd\x9a') " FF3A (upper), FF5A (lower)
+:call GT('\xef\xbc\xba', '\xef\xbc\xff') " first string is ok and equals \xef\xbd\x9a after folding, second string is illegal and was left unchanged, then the strings were bytewise compared
+:call LT('\xc3', '\xc3\x83')
+:call EQ('\xc3\xa3xYz', '\xc3\x83XyZ')
+:for n in range(0x60, 0xFF) | call LT(printf('xYz\x%.2X', n-1), printf('XyZ\x%.2X', n)) | endfor
+:for n in range(0x80, 0xBF) | call EQ(printf('xYz\xc2\x%.2XUvW', n), printf('XyZ\xc2\x%.2XuVw', n)) | endfor
+:for n in range(0xC0, 0xFF) | call LT(printf('xYz\xc2\x%.2XUvW', n), printf('XyZ\xc2\x%.2XuVw', n)) | endfor
+:call append(0, printf('%d checks passed', b:passed))
+:wq! test.out
+ENDTEST
+
On Wed, May 25, 2011 at 22:39, Ivan Krasilnikov <infnty@gmail.com> wrote:
> Hi, here's my patch for mbyte.c and a few testcases.
>
> I've eliminated those return -1's by doing a bytewise comparison of
> strings after the first corrupted character. This should make the
> comparisons transitive at least.
>

Had a bug in the patch - incorrectly checked for utf_ptr2char()'s
failure. Fixed patch and more tests in vimscript, suitable for
src/testdir/, are attached.

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