97 lines
3.6 KiB
Diff
97 lines
3.6 KiB
Diff
From f442210323e228a407dfda75b6bb7a62e91111ee Mon Sep 17 00:00:00 2001
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From: ph10 <ph10@6239d852-aaf2-0410-a92c-79f79f948069>
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Date: Sat, 23 Dec 2017 17:15:51 +0000
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Subject: [PATCH 1/3] Update pcre2demo to deal with various \K inside assertion
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anomalies.
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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git-svn-id: svn://vcs.exim.org/pcre2/code/trunk@894 6239d852-aaf2-0410-a92c-79f79f948069
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Petr Písař: Ported to 10.30.
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---
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src/pcre2demo.c | 53 +++++++++++++++++++++++++++++++++++++++++++++++++++++
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diff --git a/src/pcre2demo.c b/src/pcre2demo.c
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index 8ae49f1..5d9b321 100644
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--- a/src/pcre2demo.c
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+++ b/src/pcre2demo.c
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@@ -211,6 +211,21 @@ pcre2_match_data_create_from_pattern() above. */
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if (rc == 0)
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printf("ovector was not big enough for all the captured substrings\n");
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+/* We must guard against patterns such as /(?=.\K)/ that use \K in an assertion
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+to set the start of a match later than its end. In this demonstration program,
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+we just detect this case and give up. */
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+
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+if (ovector[0] > ovector[1])
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+ {
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+ printf("\\K was used in an assertion to set the match start after its end.\n"
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+ "From end to start the match was: %.*s\n", (int)(ovector[0] - ovector[1]),
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+ (char *)(subject + ovector[1]));
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+ printf("Run abandoned\n");
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+ pcre2_match_data_free(match_data);
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+ pcre2_code_free(re);
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+ return 1;
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+ }
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+
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/* Show substrings stored in the output vector by number. Obviously, in a real
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application you might want to do things other than print them. */
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@@ -338,6 +353,29 @@ for (;;)
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options = PCRE2_NOTEMPTY_ATSTART | PCRE2_ANCHORED;
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}
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+ /* If the previous match was not an empty string, there is one tricky case to
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+ consider. If a pattern contains \K within a lookbehind assertion at the
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+ start, the end of the matched string can be at the offset where the match
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+ started. Without special action, this leads to a loop that keeps on matching
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+ the same substring. We must detect this case and arrange to move the start on
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+ by one character. The pcre2_get_startchar() function returns the starting
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+ offset that was passed to pcre2_match(). */
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+
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+ else
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+ {
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+ PCRE2_SIZE startchar = pcre2_get_startchar(match_data);
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+ if (start_offset <= startchar)
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+ {
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+ if (startchar >= subject_length) break; /* Reached end of subject. */
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+ start_offset = startchar + 1; /* Advance by one character. */
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+ if (utf8) /* If UTF-8, it may be more */
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+ { /* than one code unit. */
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+ for (; start_offset < subject_length; start_offset++)
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+ if ((subject[start_offset] & 0xc0) != 0x80) break;
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+ }
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+ }
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+ }
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+
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/* Run the next matching operation */
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rc = pcre2_match(
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@@ -402,6 +440,21 @@ for (;;)
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if (rc == 0)
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printf("ovector was not big enough for all the captured substrings\n");
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+ /* We must guard against patterns such as /(?=.\K)/ that use \K in an
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+ assertion to set the start of a match later than its end. In this
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+ demonstration program, we just detect this case and give up. */
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+
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+ if (ovector[0] > ovector[1])
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+ {
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+ printf("\\K was used in an assertion to set the match start after its end.\n"
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+ "From end to start the match was: %.*s\n", (int)(ovector[0] - ovector[1]),
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+ (char *)(subject + ovector[1]));
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+ printf("Run abandoned\n");
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+ pcre2_match_data_free(match_data);
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+ pcre2_code_free(re);
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+ return 1;
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+ }
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+
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/* As before, show substrings stored in the output vector by number, and then
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also any named substrings. */
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--
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2.13.6
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