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| author | Andrew Gierth <rhodiumtoad@postgresql.org> | 2018-08-23 20:01:03 +0100 |
|---|---|---|
| committer | Andrew Gierth <rhodiumtoad@postgresql.org> | 2018-08-23 21:43:51 +0100 |
| commit | 0b42bd459af0532c6894d7699747986eaf4e86b5 (patch) | |
| tree | 97df9d0ef6aef9710dd2fe111e27490ccba124fe /src | |
| parent | c781a066ea4f0de0dc46e953ba55e10943199d6d (diff) | |
| download | postgresql-0b42bd459af0532c6894d7699747986eaf4e86b5.tar.gz postgresql-0b42bd459af0532c6894d7699747986eaf4e86b5.zip | |
Reduce an unnecessary O(N^3) loop in lexer.
The lexer's handling of operators contained an O(N^3) hazard when
dealing with long strings of + or - characters; it seems hard to
prevent this case from being O(N^2), but the additional N multiplier
was not needed.
Backpatch all the way since this has been there since 7.x, and it
presents at least a mild hazard in that trying to do Bind, PREPARE or
EXPLAIN on a hostile query could take excessive time (without
honouring cancels or timeouts) even if the query was never executed.
Diffstat (limited to 'src')
| -rw-r--r-- | src/backend/parser/scan.l | 27 | ||||
| -rw-r--r-- | src/fe_utils/psqlscan.l | 27 | ||||
| -rw-r--r-- | src/interfaces/ecpg/preproc/pgc.l | 29 |
3 files changed, 61 insertions, 22 deletions
diff --git a/src/backend/parser/scan.l b/src/backend/parser/scan.l index 0cd782827ac..96f51bfd596 100644 --- a/src/backend/parser/scan.l +++ b/src/backend/parser/scan.l @@ -885,20 +885,33 @@ other . * to forbid operator names like '?-' that could not be * sequences of SQL operators. */ - while (nchars > 1 && - (yytext[nchars - 1] == '+' || - yytext[nchars - 1] == '-')) + if (nchars > 1 && + (yytext[nchars - 1] == '+' || + yytext[nchars - 1] == '-')) { int ic; for (ic = nchars - 2; ic >= 0; ic--) { - if (strchr("~!@#^&|`?%", yytext[ic])) + char c = yytext[ic]; + if (c == '~' || c == '!' || c == '@' || + c == '#' || c == '^' || c == '&' || + c == '|' || c == '`' || c == '?' || + c == '%') break; } - if (ic >= 0) - break; /* found a char that makes it OK */ - nchars--; /* else remove the +/-, and check again */ + if (ic < 0) + { + /* + * didn't find a qualifying character, so remove + * all trailing [+-] + */ + do { + nchars--; + } while (nchars > 1 && + (yytext[nchars - 1] == '+' || + yytext[nchars - 1] == '-')); + } } SET_YYLLOC(); diff --git a/src/fe_utils/psqlscan.l b/src/fe_utils/psqlscan.l index 1cc587be34c..989284dc6fe 100644 --- a/src/fe_utils/psqlscan.l +++ b/src/fe_utils/psqlscan.l @@ -817,20 +817,33 @@ other . * to forbid operator names like '?-' that could not be * sequences of SQL operators. */ - while (nchars > 1 && - (yytext[nchars - 1] == '+' || - yytext[nchars - 1] == '-')) + if (nchars > 1 && + (yytext[nchars - 1] == '+' || + yytext[nchars - 1] == '-')) { int ic; for (ic = nchars - 2; ic >= 0; ic--) { - if (strchr("~!@#^&|`?%", yytext[ic])) + char c = yytext[ic]; + if (c == '~' || c == '!' || c == '@' || + c == '#' || c == '^' || c == '&' || + c == '|' || c == '`' || c == '?' || + c == '%') break; } - if (ic >= 0) - break; /* found a char that makes it OK */ - nchars--; /* else remove the +/-, and check again */ + if (ic < 0) + { + /* + * didn't find a qualifying character, so remove + * all trailing [+-] + */ + do { + nchars--; + } while (nchars > 1 && + (yytext[nchars - 1] == '+' || + yytext[nchars - 1] == '-')); + } } if (nchars < yyleng) diff --git a/src/interfaces/ecpg/preproc/pgc.l b/src/interfaces/ecpg/preproc/pgc.l index 405dee73b03..9ad50b99119 100644 --- a/src/interfaces/ecpg/preproc/pgc.l +++ b/src/interfaces/ecpg/preproc/pgc.l @@ -690,20 +690,33 @@ cppline {space}*#([^i][A-Za-z]*|{if}|{ifdef}|{ifndef}|{import})((\/\*[^*/]*\*+ * to forbid operator names like '?-' that could not be * sequences of SQL operators. */ - while (nchars > 1 && - (yytext[nchars-1] == '+' || - yytext[nchars-1] == '-')) + if (nchars > 1 && + (yytext[nchars - 1] == '+' || + yytext[nchars - 1] == '-')) { int ic; - for (ic = nchars-2; ic >= 0; ic--) + for (ic = nchars - 2; ic >= 0; ic--) { - if (strchr("~!@#^&|`?%", yytext[ic])) + char c = yytext[ic]; + if (c == '~' || c == '!' || c == '@' || + c == '#' || c == '^' || c == '&' || + c == '|' || c == '`' || c == '?' || + c == '%') break; } - if (ic >= 0) - break; /* found a char that makes it OK */ - nchars--; /* else remove the +/-, and check again */ + if (ic < 0) + { + /* + * didn't find a qualifying character, so remove + * all trailing [+-] + */ + do { + nchars--; + } while (nchars > 1 && + (yytext[nchars - 1] == '+' || + yytext[nchars - 1] == '-')); + } } if (nchars < yyleng) |