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/**
* Test the behavior of very, very long regex patterns.
*/
(function() {
"use strict";
const coll = db.regex_limit;
coll.drop();
const kMaxRegexPatternLen = 16384;
// Populate the collection with a document containing a very long string.
assert.commandWorked(coll.insert({z: "c".repeat(100000)}));
function tryRegexLength(coll, n) {
const re = "c".repeat(n);
const res = coll.runCommand("find", {filter: {z: {$regex: re}}});
if (res.ok == 1)
return true;
if (res.ok == 0 && res.code == 51091)
return false;
// Something else went wrong.
assert.commandWorked(res);
}
// Returns the longest regex length the server will accept.
function probeMaxPatternLength(coll) {
// Exponential search and bisect to find the exact failure point.
// Half-open interval `range`: [lastKnownGood, firstKnownBad).
let range = [1 << 0, 1 << 0];
while (true) {
if (!tryRegexLength(coll, range[1]))
break;
range[0] = range[1];
range[1] *= 2;
}
while (true) {
let mid = Math.floor((range[0] + range[1]) / 2);
if (mid == range[0])
break;
if (tryRegexLength(coll, mid)) {
range[0] = mid;
} else {
range[1] = mid;
}
}
return range[0];
}
assert(probeMaxPatternLength(coll) >= kMaxRegexPatternLen);
// Test that a regex exactly at the maximum allowable pattern length can find a document.
const patternMaxLen = "c".repeat(kMaxRegexPatternLen);
assert.eq(1, coll.find({z: {$regex: patternMaxLen}}).itcount());
assert.eq(1, coll.find({z: {$in: [new RegExp(patternMaxLen)]}}).itcount());
// Test that a regex pattern exceeding the limit fails.
const patternTooLong = "c".repeat(2 * kMaxRegexPatternLen + 1);
assert.commandFailedWithCode(coll.runCommand("find", {filter: {z: {$regex: patternTooLong}}}),
51091);
assert.commandFailedWithCode(
coll.runCommand("find", {filter: {z: {$in: [new RegExp(patternTooLong)]}}}), 51091);
}());
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