FORTIFY_SOURCE: strcat / strncat optimize

__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

3 files changed, 312 insertions, 0 deletions

diff --git a/tests/fortify1_test.cpp b/tests/fortify1_test.cpp
index 70d458a..a9d8afd 100644
--- a/tests/fortify1_test.cpp
+++ b/tests/fortify1_test.cpp
@@ -76,3 +76,166 @@ TEST(Fortify1_DeathTest, strncat2_fortified) {
   size_t n = atoi("10"); // avoid compiler optimizations
   ASSERT_EXIT(strncat(buf, "0123456789", n), testing::KilledBySignal(SIGSEGV), "");
 }
+
+TEST(Fortify1_DeathTest, strcat_fortified) {
+  ::testing::FLAGS_gtest_death_test_style = "threadsafe";
+  char src[11];
+  strcpy(src, "0123456789");
+  char buf[10];
+  buf[0] = '\0';
+  ASSERT_EXIT(strcat(buf, src), testing::KilledBySignal(SIGSEGV), "");
+}
+
+extern "C" char* __strncat_chk(char*, const char*, size_t, size_t);
+extern "C" char* __strcat_chk(char*, const char*, size_t);
+
+TEST(Fortify1, strncat) {
+  char buf[10];
+  memset(buf, 'A', sizeof(buf));
+  buf[0] = 'a';
+  buf[1] = '\0';
+  char* res = __strncat_chk(buf, "01234", sizeof(buf) - strlen(buf) - 1, sizeof(buf));
+  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(Fortify1, strncat2) {
+  char buf[10];
+  memset(buf, 'A', sizeof(buf));
+  buf[0] = 'a';
+  buf[1] = '\0';
+  char* res = __strncat_chk(buf, "0123456789", 5, sizeof(buf));
+  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(Fortify1, strncat3) {
+  char buf[10];
+  memset(buf, 'A', sizeof(buf));
+  buf[0] = '\0';
+  char* res = __strncat_chk(buf, "0123456789", 5, sizeof(buf));
+  ASSERT_EQ(buf, res);
+  ASSERT_EQ('0',  buf[0]);
+  ASSERT_EQ('1',  buf[1]);
+  ASSERT_EQ('2',  buf[2]);
+  ASSERT_EQ('3',  buf[3]);
+  ASSERT_EQ('4',  buf[4]);
+  ASSERT_EQ('\0', buf[5]);
+  ASSERT_EQ('A',  buf[6]);
+  ASSERT_EQ('A',  buf[7]);
+  ASSERT_EQ('A',  buf[8]);
+  ASSERT_EQ('A',  buf[9]);
+}
+
+TEST(Fortify1, strncat4) {
+  char buf[10];
+  memset(buf, 'A', sizeof(buf));
+  buf[9] = '\0';
+  char* res = __strncat_chk(buf, "", 5, sizeof(buf));
+  ASSERT_EQ(buf, res);
+  ASSERT_EQ('A',  buf[0]);
+  ASSERT_EQ('A',  buf[1]);
+  ASSERT_EQ('A',  buf[2]);
+  ASSERT_EQ('A',  buf[3]);
+  ASSERT_EQ('A',  buf[4]);
+  ASSERT_EQ('A',  buf[5]);
+  ASSERT_EQ('A',  buf[6]);
+  ASSERT_EQ('A',  buf[7]);
+  ASSERT_EQ('A',  buf[8]);
+  ASSERT_EQ('\0', buf[9]);
+}
+
+TEST(Fortify1, strncat5) {
+  char buf[10];
+  memset(buf, 'A', sizeof(buf));
+  buf[0] = 'a';
+  buf[1] = '\0';
+  char* res = __strncat_chk(buf, "01234567", 8, sizeof(buf));
+  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(Fortify1, strncat6) {
+  char buf[10];
+  memset(buf, 'A', sizeof(buf));
+  buf[0] = 'a';
+  buf[1] = '\0';
+  char* res = __strncat_chk(buf, "01234567", 9, sizeof(buf));
+  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(Fortify1, strcat) {
+  char buf[10];
+  memset(buf, 'A', sizeof(buf));
+  buf[0] = 'a';
+  buf[1] = '\0';
+  char* res = __strcat_chk(buf, "01234", sizeof(buf));
+  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(Fortify1, strcat2) {
+  char buf[10];
+  memset(buf, 'A', sizeof(buf));
+  buf[0] = 'a';
+  buf[1] = '\0';
+  char* res = __strcat_chk(buf, "01234567", sizeof(buf));
+  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]);
+}
diff --git a/tests/fortify2_test.cpp b/tests/fortify2_test.cpp
index c937e91..eee5770 100644
--- a/tests/fortify2_test.cpp
+++ b/tests/fortify2_test.cpp
@@ -80,6 +80,32 @@ TEST(Fortify2_DeathTest, strncat2_fortified2) {
   ASSERT_EXIT(strncat(myfoo.a, "0123456789", n), testing::KilledBySignal(SIGSEGV), "");
 }
 
+TEST(Fortify2_DeathTest, strncat3_fortified2) {
+  ::testing::FLAGS_gtest_death_test_style = "threadsafe";
+  foo myfoo;
+  memcpy(myfoo.a, "0123456789", sizeof(myfoo.a)); // unterminated string
+  myfoo.b[0] = '\0';
+  size_t n = atoi("10"); // avoid compiler optimizations
+  ASSERT_EXIT(strncat(myfoo.b, myfoo.a, n), testing::KilledBySignal(SIGSEGV), "");
+}
+
+TEST(Fortify2_DeathTest, strcat_fortified2) {
+  ::testing::FLAGS_gtest_death_test_style = "threadsafe";
+  char src[11];
+  strcpy(src, "0123456789");
+  foo myfoo;
+  myfoo.a[0] = '\0';
+  ASSERT_EXIT(strcat(myfoo.a, src), testing::KilledBySignal(SIGSEGV), "");
+}
+
+TEST(Fortify2_DeathTest, strcat2_fortified2) {
+  ::testing::FLAGS_gtest_death_test_style = "threadsafe";
+  foo myfoo;
+  memcpy(myfoo.a, "0123456789", sizeof(myfoo.a)); // unterminated string
+  myfoo.b[0] = '\0';
+  ASSERT_EXIT(strcat(myfoo.b, myfoo.a), testing::KilledBySignal(SIGSEGV), "");
+}
+
 /***********************************************************/
 /* TESTS BELOW HERE DUPLICATE TESTS FROM fortify1_test.cpp */
 /***********************************************************/
@@ -138,3 +164,12 @@ TEST(Fortify2_DeathTest, strncat2_fortified) {
   size_t n = atoi("10"); // avoid compiler optimizations
   ASSERT_EXIT(strncat(buf, "0123456789", n), testing::KilledBySignal(SIGSEGV), "");
 }
+
+TEST(Fortify2_DeathTest, strcat_fortified) {
+  ::testing::FLAGS_gtest_death_test_style = "threadsafe";
+  char src[11];
+  strcpy(src, "0123456789");
+  char buf[10];
+  buf[0] = '\0';
+  ASSERT_EXIT(strcat(buf, src), testing::KilledBySignal(SIGSEGV), "");
+}
diff --git a/tests/string_test.cpp b/tests/string_test.cpp
index 63bfadb..a0924dc 100644
--- a/tests/string_test.cpp
+++ b/tests/string_test.cpp
@@ -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";