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FORTIFY_SOURCE: strcat / strncat optimize

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__strcat_chk and __strncat_chk are slightly inefficient,
because they end up traversing over the same memory region
two times.

This change optimizes __strcat_chk / __strncat_chk so they
only access the memory once. Although I haven't benchmarked these
changes, it should improve the performance of these functions.

__strlen_chk - expose this function, even if -D_FORTIFY_SOURCE
isn't defined. This is needed to compile libc itself without
-D_FORTIFY_SOURCE.

Change-Id: Id2c70dff55a276b47c59db27a03734d659f84b74
This commit is contained in:
Nick Kralevich
2013-05-30 16:48:53 -07:00
parent 72f59c84fd
commit cf870199d5
7 changed files with 354 additions and 40 deletions
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114
tests/string_test.cpp
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@@ -209,6 +209,120 @@ TEST(string, strcat) {
}
}
TEST(string, strcat2) {
char buf[10];
memset(buf, 'A', sizeof(buf));
buf[0] = 'a';
buf[1] = '\0';
char* res = strcat(buf, "01234");
ASSERT_EQ(buf, res);
ASSERT_EQ('a', buf[0]);
ASSERT_EQ('0', buf[1]);
ASSERT_EQ('1', buf[2]);
ASSERT_EQ('2', buf[3]);
ASSERT_EQ('3', buf[4]);
ASSERT_EQ('4', buf[5]);
ASSERT_EQ('\0', buf[6]);
ASSERT_EQ('A', buf[7]);
ASSERT_EQ('A', buf[8]);
ASSERT_EQ('A', buf[9]);
}
TEST(string, strcat3) {
char buf[10];
memset(buf, 'A', sizeof(buf));
buf[0] = 'a';
buf[1] = '\0';
char* res = strcat(buf, "01234567");
ASSERT_EQ(buf, res);
ASSERT_EQ('a', buf[0]);
ASSERT_EQ('0', buf[1]);
ASSERT_EQ('1', buf[2]);
ASSERT_EQ('2', buf[3]);
ASSERT_EQ('3', buf[4]);
ASSERT_EQ('4', buf[5]);
ASSERT_EQ('5', buf[6]);
ASSERT_EQ('6', buf[7]);
ASSERT_EQ('7', buf[8]);
ASSERT_EQ('\0', buf[9]);
}
TEST(string, strncat2) {
char buf[10];
memset(buf, 'A', sizeof(buf));
buf[0] = 'a';
buf[1] = '\0';
char* res = strncat(buf, "01234", sizeof(buf) - strlen(buf) - 1);
ASSERT_EQ(buf, res);
ASSERT_EQ('a', buf[0]);
ASSERT_EQ('0', buf[1]);
ASSERT_EQ('1', buf[2]);
ASSERT_EQ('2', buf[3]);
ASSERT_EQ('3', buf[4]);
ASSERT_EQ('4', buf[5]);
ASSERT_EQ('\0', buf[6]);
ASSERT_EQ('A', buf[7]);
ASSERT_EQ('A', buf[8]);
ASSERT_EQ('A', buf[9]);
}
TEST(string, strncat3) {
char buf[10];
memset(buf, 'A', sizeof(buf));
buf[0] = 'a';
buf[1] = '\0';
char* res = strncat(buf, "0123456789", 5);
ASSERT_EQ(buf, res);
ASSERT_EQ('a', buf[0]);
ASSERT_EQ('0', buf[1]);
ASSERT_EQ('1', buf[2]);
ASSERT_EQ('2', buf[3]);
ASSERT_EQ('3', buf[4]);
ASSERT_EQ('4', buf[5]);
ASSERT_EQ('\0', buf[6]);
ASSERT_EQ('A', buf[7]);
ASSERT_EQ('A', buf[8]);
ASSERT_EQ('A', buf[9]);
}
TEST(string, strncat4) {
char buf[10];
memset(buf, 'A', sizeof(buf));
buf[0] = 'a';
buf[1] = '\0';
char* res = strncat(buf, "01234567", 8);
ASSERT_EQ(buf, res);
ASSERT_EQ('a', buf[0]);
ASSERT_EQ('0', buf[1]);
ASSERT_EQ('1', buf[2]);
ASSERT_EQ('2', buf[3]);
ASSERT_EQ('3', buf[4]);
ASSERT_EQ('4', buf[5]);
ASSERT_EQ('5', buf[6]);
ASSERT_EQ('6', buf[7]);
ASSERT_EQ('7', buf[8]);
ASSERT_EQ('\0', buf[9]);
}
TEST(string, strncat5) {
char buf[10];
memset(buf, 'A', sizeof(buf));
buf[0] = 'a';
buf[1] = '\0';
char* res = strncat(buf, "01234567", 9);
ASSERT_EQ(buf, res);
ASSERT_EQ('a', buf[0]);
ASSERT_EQ('0', buf[1]);
ASSERT_EQ('1', buf[2]);
ASSERT_EQ('2', buf[3]);
ASSERT_EQ('3', buf[4]);
ASSERT_EQ('4', buf[5]);
ASSERT_EQ('5', buf[6]);
ASSERT_EQ('6', buf[7]);
ASSERT_EQ('7', buf[8]);
ASSERT_EQ('\0', buf[9]);
}
TEST(string, strchr_with_0) {
char buf[10];
const char* s = "01234";