diff options
| author | Andrew Gierth <rhodiumtoad@postgresql.org> | 2018-08-23 16:35:33 +0100 |
|---|---|---|
| committer | Andrew Gierth <rhodiumtoad@postgresql.org> | 2018-08-23 21:42:40 +0100 |
| commit | d4a63f829702cf28adb5db7e2ed44d2d9d893451 (patch) | |
| tree | e3e5164836e920f8fa0fa8768e84f98578fecfd7 /src/interfaces | |
| parent | 5ca00774194dc179d02867d536b73eb85fffd227 (diff) | |
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/interfaces')
| -rw-r--r-- | src/interfaces/ecpg/preproc/pgc.l | 29 |
1 files changed, 21 insertions, 8 deletions
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) |