49816 2010-11-19 11:25:39 -0800 Remove a couple unneeded overflow checks 2010-11-29 14:06:53 -0800 1 1 1 Unclassified WebKit WebKit Misc. 528+ (Nightly build) All All RESOLVED FIXED P2 Normal --- 1 darin darin ap cevans darin kling oldest_to_newest 311583 0 darin 2010-11-19 11:25:39 -0800 Remove a couple unneeded overflow checks 311584 1 74408 darin 2010-11-19 11:27:31 -0800 Created attachment 74408 Patch 311706 2 74408 kling 2010-11-19 14:58:42 -0800 Comment on attachment 74408 Patch r=me 311858 3 ap 2010-11-19 21:02:59 -0800 + // We need to be sure we can double the length without overflowing. + // Since the passed-in length is the length of an actual existing + // string, and we can guarantee that doesn't occupy the entire + // address space, we can just assert here and there's no need for + // a runtime check. + ASSERT(length <= numeric_limits<size_t>::max() / 2); This comment isn't sufficient for me to understand. If the existing string takes 51% of address space, why doesn't doubling that cause an overflow? 311881 4 kling 2010-11-19 23:11:35 -0800 (In reply to comment #3) > This comment isn't sufficient for me to understand. If the existing string takes 51% of address space, why doesn't doubling that cause an overflow? The _existing_ string is length*2 bytes large, so we know that length*2 fits in the address space. 312350 5 darin 2010-11-22 08:28:02 -0800 (In reply to comment #3) > + // We need to be sure we can double the length without overflowing. > + // Since the passed-in length is the length of an actual existing > + // string, and we can guarantee that doesn't occupy the entire > + // address space, we can just assert here and there's no need for > + // a runtime check. > + ASSERT(length <= numeric_limits<size_t>::max() / 2); > > This comment isn't sufficient for me to understand. If the existing string takes 51% of address space, why doesn't doubling that cause an overflow? If the string’s length was the same as 51% of the address space, the string’s size would be 102% of the address space, since characters are two bytes each. I should refine the comment to make this clearer. 314627 6 darin 2010-11-29 14:06:53 -0800 Committed r72831: <http://trac.webkit.org/changeset/72831> 74408 2010-11-19 11:27:31 -0800 2010-11-19 14:58:42 -0800 Patch bug-49816-20101119112729.patch text/plain 3343 darin SW5kZXg6IEphdmFTY3JpcHRDb3JlL0NoYW5nZUxvZwo9PT09PT09PT09PT09PT09PT09PT09PT09 PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09Ci0tLSBKYXZhU2NyaXB0 Q29yZS9DaGFuZ2VMb2cJKHJldmlzaW9uIDcyNDIxKQorKysgSmF2YVNjcmlwdENvcmUvQ2hhbmdl TG9nCSh3b3JraW5nIGNvcHkpCkBAIC0xLDMgKzEsMTQgQEAKKzIwMTAtMTEtMTkgIERhcmluIEFk bGVyICA8ZGFyaW5AYXBwbGUuY29tPgorCisgICAgICAgIFJldmlld2VkIGJ5IE5PQk9EWSAoT09Q UyEpLgorCisgICAgICAgIFJlbW92ZSBhIGNvdXBsZSB1bm5lZWRlZCBvdmVyZmxvdyBjaGVja3MK KyAgICAgICAgaHR0cHM6Ly9idWdzLndlYmtpdC5vcmcvc2hvd19idWcuY2dpP2lkPTQ5ODE2CisK KyAgICAgICAgKiB3dGYvdGV4dC9DU3RyaW5nLmNwcDoKKyAgICAgICAgKFdURjo6Q1N0cmluZzo6 aW5pdCk6IFVzZSBhbiBBU1NFUlQgaW5zdGVhZCBvZgorICAgICAgICBhbiBvdmVyZmxvdyBjaGVj ayB3aXRoIENSQVNILgorCiAyMDEwLTExLTE4ICBTdGV2ZSBGYWxrZW5idXJnICA8c2ZhbGtlbkBh cHBsZS5jb20+CiAKICAgICAgICAgUmV2aWV3ZWQgYnkgQWRhbSBSb2Jlbi4KSW5kZXg6IEphdmFT Y3JpcHRDb3JlL3d0Zi90ZXh0L0NTdHJpbmcuY3BwCj09PT09PT09PT09PT09PT09PT09PT09PT09 PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT0KLS0tIEphdmFTY3JpcHRD b3JlL3d0Zi90ZXh0L0NTdHJpbmcuY3BwCShyZXZpc2lvbiA3MjQxMSkKKysrIEphdmFTY3JpcHRD b3JlL3d0Zi90ZXh0L0NTdHJpbmcuY3BwCSh3b3JraW5nIGNvcHkpCkBAIC00OSw4ICs0OSwxMiBA QCB2b2lkIENTdHJpbmc6OmluaXQoY29uc3QgY2hhciogc3RyLCBzaXplCiAgICAgaWYgKCFzdHIp CiAgICAgICAgIHJldHVybjsKIAotICAgIGlmIChsZW5ndGggPj0gbnVtZXJpY19saW1pdHM8c2l6 ZV90Pjo6bWF4KCkpCi0gICAgICAgIENSQVNIKCk7CisgICAgLy8gV2UgbmVlZCB0byBiZSBzdXJl IHdlIGNhbiBhZGQgMSB0byBsZW5ndGggd2l0aG91dCBvdmVyZmxvd2luZy4KKyAgICAvLyBTaW5j ZSB0aGUgcGFzc2VkLWluIGxlbmd0aCBpcyB0aGUgbGVuZ3RoIG9mIGFuIGFjdHVhbCBleGlzdGlu ZworICAgIC8vIHN0cmluZywgYW5kIHdlIGNhbiBndWFyYW50ZWUgdGhhdCBkb2Vzbid0IG9jY3Vw eSB0aGUgZW50aXJlCisgICAgLy8gYWRkcmVzcyBzcGFjZSwgd2UgY2FuIGp1c3QgYXNzZXJ0IGhl cmUgYW5kIHRoZXJlJ3Mgbm8gbmVlZCBmb3IKKyAgICAvLyBhIHJ1bnRpbWUgY2hlY2suCisgICAg QVNTRVJUKGxlbmd0aCA8IG51bWVyaWNfbGltaXRzPHNpemVfdD46Om1heCgpKTsKIAogICAgIG1f YnVmZmVyID0gQ1N0cmluZ0J1ZmZlcjo6Y3JlYXRlKGxlbmd0aCArIDEpOwogICAgIG1lbWNweSht X2J1ZmZlci0+bXV0YWJsZURhdGEoKSwgc3RyLCBsZW5ndGgpOyAKSW5kZXg6IFdlYkNvcmUvQ2hh bmdlTG9nCj09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09 PT09PT09PT09PT09PT09PT0KLS0tIFdlYkNvcmUvQ2hhbmdlTG9nCShyZXZpc2lvbiA3MjQyMSkK KysrIFdlYkNvcmUvQ2hhbmdlTG9nCSh3b3JraW5nIGNvcHkpCkBAIC0xLDMgKzEsMTQgQEAKKzIw MTAtMTEtMTkgIERhcmluIEFkbGVyICA8ZGFyaW5AYXBwbGUuY29tPgorCisgICAgICAgIFJldmll d2VkIGJ5IE5PQk9EWSAoT09QUyEpLgorCisgICAgICAgIFJlbW92ZSBhIGNvdXBsZSB1bm5lZWRl ZCBvdmVyZmxvdyBjaGVja3MKKyAgICAgICAgaHR0cHM6Ly9idWdzLndlYmtpdC5vcmcvc2hvd19i dWcuY2dpP2lkPTQ5ODE2CisKKyAgICAgICAgKiBwbGF0Zm9ybS90ZXh0L1RleHRDb2RlY1VURjE2 LmNwcDoKKyAgICAgICAgKFdlYkNvcmU6OlRleHRDb2RlY1VURjE2OjplbmNvZGUpOiBVc2UgYW4g QVNTRVJUIGluc3RlYWQgb2YKKyAgICAgICAgYW4gb3ZlcmZsb3cgY2hlY2sgd2l0aCBDUkFTSC4K KwogMjAxMC0xMS0xOSAgU3RldmUgRmFsa2VuYnVyZyAgPHNmYWxrZW5AYXBwbGUuY29tPgogCiAg ICAgICAgIFdpbmRvd3MgYnVpbGQgZml4LiBSZW1vdmUgbGVmdG92ZXIgRGVidWdfSW50ZXJuYWwg dXNlLgpJbmRleDogV2ViQ29yZS9wbGF0Zm9ybS90ZXh0L1RleHRDb2RlY1VURjE2LmNwcAo9PT09 PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09 PT09PT09Ci0tLSBXZWJDb3JlL3BsYXRmb3JtL3RleHQvVGV4dENvZGVjVVRGMTYuY3BwCShyZXZp c2lvbiA3MjQxMSkKKysrIFdlYkNvcmUvcGxhdGZvcm0vdGV4dC9UZXh0Q29kZWNVVEYxNi5jcHAJ KHdvcmtpbmcgY29weSkKQEAgLTEsNSArMSw1IEBACiAvKgotICogQ29weXJpZ2h0IChDKSAyMDA0 LCAyMDA2LCAyMDA4IEFwcGxlIEluYy4gQWxsIHJpZ2h0cyByZXNlcnZlZC4KKyAqIENvcHlyaWdo dCAoQykgMjAwNCwgMjAwNiwgMjAwOCwgMjAxMCBBcHBsZSBJbmMuIEFsbCByaWdodHMgcmVzZXJ2 ZWQuCiAgKgogICogUmVkaXN0cmlidXRpb24gYW5kIHVzZSBpbiBzb3VyY2UgYW5kIGJpbmFyeSBm b3Jtcywgd2l0aCBvciB3aXRob3V0CiAgKiBtb2RpZmljYXRpb24sIGFyZSBwZXJtaXR0ZWQgcHJv dmlkZWQgdGhhdCB0aGUgZm9sbG93aW5nIGNvbmRpdGlvbnMKQEAgLTExNyw4ICsxMTcsMTIgQEAg U3RyaW5nIFRleHRDb2RlY1VURjE2OjpkZWNvZGUoY29uc3QgY2hhcgogCiBDU3RyaW5nIFRleHRD b2RlY1VURjE2OjplbmNvZGUoY29uc3QgVUNoYXIqIGNoYXJhY3RlcnMsIHNpemVfdCBsZW5ndGgs IFVuZW5jb2RhYmxlSGFuZGxpbmcpCiB7Ci0gICAgaWYgKGxlbmd0aCA+IG51bWVyaWNfbGltaXRz PHNpemVfdD46Om1heCgpIC8gMikKLSAgICAgICAgQ1JBU0goKTsKKyAgICAvLyBXZSBuZWVkIHRv IGJlIHN1cmUgd2UgY2FuIGRvdWJsZSB0aGUgbGVuZ3RoIHdpdGhvdXQgb3ZlcmZsb3dpbmcuCisg ICAgLy8gU2luY2UgdGhlIHBhc3NlZC1pbiBsZW5ndGggaXMgdGhlIGxlbmd0aCBvZiBhbiBhY3R1 YWwgZXhpc3RpbmcKKyAgICAvLyBzdHJpbmcsIGFuZCB3ZSBjYW4gZ3VhcmFudGVlIHRoYXQgZG9l c24ndCBvY2N1cHkgdGhlIGVudGlyZQorICAgIC8vIGFkZHJlc3Mgc3BhY2UsIHdlIGNhbiBqdXN0 IGFzc2VydCBoZXJlIGFuZCB0aGVyZSdzIG5vIG5lZWQgZm9yCisgICAgLy8gYSBydW50aW1lIGNo ZWNrLgorICAgIEFTU0VSVChsZW5ndGggPD0gbnVtZXJpY19saW1pdHM8c2l6ZV90Pjo6bWF4KCkg LyAyKTsKIAogICAgIGNoYXIqIGJ5dGVzOwogICAgIENTdHJpbmcgc3RyaW5nID0gQ1N0cmluZzo6 bmV3VW5pbml0aWFsaXplZChsZW5ndGggKiAyLCBieXRlcyk7Cg==