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awk: fix subst code to handle "start of word" pattern correctly (needs REG_STARTEND)
function old new delta awk_sub 637 714 +77 Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko
parent
113685fbcd
commit
2ca39ffd44
@ -2504,17 +2504,46 @@ static int awk_sub(node *rn, const char *repl, int nm, var *src, var *dest /*,in
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regex_t sreg, *regex;
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/* True only if called to implement gensub(): */
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int subexp = (src != dest);
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#if defined(REG_STARTEND)
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const char *src_string;
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size_t src_strlen;
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regexec_flags = REG_STARTEND;
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#else
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regexec_flags = 0;
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#endif
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resbuf = NULL;
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residx = 0;
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match_no = 0;
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regexec_flags = 0;
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regex = as_regex(rn, &sreg);
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sp = getvar_s(src ? src : intvar[F0]);
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#if defined(REG_STARTEND)
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src_string = sp;
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src_strlen = strlen(src_string);
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#endif
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replen = strlen(repl);
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while (regexec(regex, sp, 10, pmatch, regexec_flags) == 0) {
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int so = pmatch[0].rm_so;
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int eo = pmatch[0].rm_eo;
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for (;;) {
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int so, eo;
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#if defined(REG_STARTEND)
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// REG_STARTEND: "This flag is a BSD extension, not present in POSIX"
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size_t start_ofs = sp - src_string;
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pmatch[0].rm_so = start_ofs;
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pmatch[0].rm_eo = src_strlen;
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if (regexec(regex, src_string, 10, pmatch, regexec_flags) != 0)
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break;
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eo = pmatch[0].rm_eo - start_ofs;
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so = pmatch[0].rm_so - start_ofs;
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#else
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// BUG:
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// gsub(/\<b*/,"") on "abc" matches empty string at "a...",
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// advances sp one char (see "Empty match" comment later) to "bc"
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// ... and erroneously matches "b" even though it is NOT at the word start.
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enum { start_ofs = 0 };
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if (regexec(regex, sp, 10, pmatch, regexec_flags) != 0)
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break;
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so = pmatch[0].rm_so;
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eo = pmatch[0].rm_eo;
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#endif
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//bb_error_msg("match %u: [%u,%u] '%s'%p", match_no+1, so, eo, sp,sp);
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resbuf = qrealloc(resbuf, residx + eo + replen, &resbufsize);
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@ -2543,7 +2572,7 @@ static int awk_sub(node *rn, const char *repl, int nm, var *src, var *dest /*,in
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}
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n = pmatch[j].rm_eo - pmatch[j].rm_so;
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resbuf = qrealloc(resbuf, residx + replen + n, &resbufsize);
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memcpy(resbuf + residx, sp + pmatch[j].rm_so, n);
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memcpy(resbuf + residx, sp + pmatch[j].rm_so - start_ofs, n);
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residx += n;
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} else
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resbuf[residx++] = c;
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@ -2557,12 +2586,6 @@ static int awk_sub(node *rn, const char *repl, int nm, var *src, var *dest /*,in
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if (eo == so) {
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/* Empty match (e.g. "b*" will match anywhere).
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* Advance by one char. */
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//BUG (bug 1333):
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//gsub(/\<b*/,"") on "abc" will reach this point, advance to "bc"
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//... and will erroneously match "b" even though it is NOT at the word start.
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//we need REG_NOTBOW but it does not exist...
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//TODO: if EXTRA_COMPAT=y, use GNU matching and re_search,
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//it should be able to do it correctly.
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/* Subtle: this is safe only because
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* qrealloc allocated at least one extra byte */
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resbuf[residx] = *sp;
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@ -2571,7 +2594,7 @@ static int awk_sub(node *rn, const char *repl, int nm, var *src, var *dest /*,in
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sp++;
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residx++;
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}
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regexec_flags = REG_NOTBOL;
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regexec_flags |= REG_NOTBOL;
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}
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resbuf = qrealloc(resbuf, residx + strlen(sp), &resbufsize);
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@ -557,14 +557,12 @@ testing 'awk gensub backslashes \' \
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'awk '$sq'BEGIN { s="\\"; print "s=" s; print gensub("a", s, "g", "a|a") }'$sq \
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's=\\
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\\|\\
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' \
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'' ''
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' '' ''
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testing 'awk gensub backslashes \\' \
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'awk '$sq'BEGIN { s="\\\\"; print "s=" s; print gensub("a", s, "g", "a|a") }'$sq \
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's=\\\\
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\\|\\
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' \
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'' ''
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' '' ''
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# gawk 5.1.1 handles trailing unpaired \ inconsistently.
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# If replace string is single \, it is used verbatim,
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# but if it is \\\ (three slashes), gawk uses "\<NUL>" (!!!), not "\\" as you would expect.
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@ -572,31 +570,35 @@ testing 'awk gensub backslashes \\\' \
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'awk '$sq'BEGIN { s="\\\\\\"; print "s=" s; print gensub("a", s, "g", "a|a") }'$sq \
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's=\\\\\\
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\\\\|\\\\
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' \
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'' ''
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' '' ''
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testing 'awk gensub backslashes \\\\' \
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'awk '$sq'BEGIN { s="\\\\\\\\"; print "s=" s; print gensub("a", s, "g", "a|a") }'$sq \
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's=\\\\\\\\
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\\\\|\\\\
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' \
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'' ''
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' '' ''
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testing 'awk gensub backslashes \&' \
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'awk '$sq'BEGIN { s="\\&"; print "s=" s; print gensub("a", s, "g", "a|a") }'$sq \
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's=\\&
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&|&
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' \
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'' ''
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' '' ''
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testing 'awk gensub backslashes \0' \
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'awk '$sq'BEGIN { s="\\0"; print "s=" s; print gensub("a", s, "g", "a|a") }'$sq \
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's=\\0
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a|a
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' \
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'' ''
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' '' ''
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testing 'awk gensub backslashes \\0' \
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'awk '$sq'BEGIN { s="\\\\0"; print "s=" s; print gensub("a", s, "g", "a|a") }'$sq \
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's=\\\\0
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\\0|\\0
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' \
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' '' ''
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# The "b" in "abc" should not match <b* pattern.
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# Currently we use REG_STARTEND ("This flag is a BSD extension, not present in POSIX")
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# to implement the code to handle this correctly, but if your libc has no REG_STARTEND,
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# the alternative code mishandles this case.
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testing 'awk gsub erroneous word start match' \
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"awk 'BEGIN { a=\"abc\"; gsub(/\<b*/,\"\",a); print a }'" \
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'abc\n' \
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'' ''
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exit $FAILCOUNT
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