libc: strlcpy/strlcat shouldn't bzero the rest of buf
#114259
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When running Bionic's testsuite over llvm-libc, tests broke because
e.g.,
```
const char *str = "abc";
char buf[7]{"111111"};
strlcpy(buf, str, 7);
ASSERT_EQ(buf, {'1', '1', '1', '\0', '\0', '\0', '\0'});
```
On my machine (Debian w/ glibc and clang-16), a `printf` loop over `buf`
gets unrolled into a series of const `printf`` at compile-time:
```
printf("%d\n", '1');
printf("%d\n", '1');
printf("%d\n", '1');
printf("%d\n", 0);
printf("%d\n", '1');
printf("%d\n", '1');
printf("%d\n", 0);
```
Seems best to match existing precedent here.
Member
|
@llvm/pr-subscribers-libc Author: George Burgess IV (gburgessiv) ChangesWhen running Bionic's testsuite over llvm-libc, tests broke because e.g., On my machine (Debian w/ glibc and clang-16), a Seems best to match existing precedent here. Full diff: https://github.com/llvm/llvm-project/pull/114259.diff 3 Files Affected:
diff --git a/libc/src/string/string_utils.h b/libc/src/string/string_utils.h
index 78381e46e480dd..240b28f15718a8 100644
--- a/libc/src/string/string_utils.h
+++ b/libc/src/string/string_utils.h
@@ -221,7 +221,7 @@ LIBC_INLINE size_t strlcpy(char *__restrict dst, const char *__restrict src,
return len;
size_t n = len < size - 1 ? len : size - 1;
inline_memcpy(dst, src, n);
- inline_bzero(dst + n, size - n);
+ dst[n] = '\0';
return len;
}
diff --git a/libc/test/src/string/strlcat_test.cpp b/libc/test/src/string/strlcat_test.cpp
index 1ffa4b0e921e2b..5757fc92b39d2a 100644
--- a/libc/test/src/string/strlcat_test.cpp
+++ b/libc/test/src/string/strlcat_test.cpp
@@ -27,6 +27,15 @@ TEST(LlvmLibcStrlcatTest, Smaller) {
EXPECT_STREQ(buf, "abcd");
}
+TEST(LlvmLibcStrlcatTest, SmallerNoOverwriteAfter0) {
+ const char *str = "cd";
+ char buf[8]{"ab\0\0efg"};
+
+ EXPECT_EQ(LIBC_NAMESPACE::strlcat(buf, str, 8), size_t(4));
+ EXPECT_STREQ(buf, "abcd");
+ EXPECT_STREQ(buf + 5, "fg");
+}
+
TEST(LlvmLibcStrlcatTest, No0) {
const char *str = "cd";
char buf[7]{"ab"};
diff --git a/libc/test/src/string/strlcpy_test.cpp b/libc/test/src/string/strlcpy_test.cpp
index 5a1e30c12963f3..ecf0e925a265c3 100644
--- a/libc/test/src/string/strlcpy_test.cpp
+++ b/libc/test/src/string/strlcpy_test.cpp
@@ -25,6 +25,5 @@ TEST(LlvmLibcStrlcpyTest, Smaller) {
EXPECT_EQ(LIBC_NAMESPACE::strlcpy(buf, str, 7), size_t(3));
EXPECT_STREQ(buf, "abc");
- for (const char *p = buf + 3; p < buf + 7; p++)
- EXPECT_EQ(*p, '\0');
+ EXPECT_STREQ(buf + 4, "11");
}
|
nickdesaulniers
approved these changes
Oct 30, 2024
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nickdesaulniers
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Looks like this mistake has existed since the introduction of this helper b118330
Thanks for the patch!
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Author
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Thanks for reviewing! I'll press the button once buildkite checks pass. |
smallp-o-p
pushed a commit
to smallp-o-p/llvm-project
that referenced
this pull request
Nov 3, 2024
When running Bionic's testsuite over llvm-libc, tests broke because
e.g.,
```
const char *str = "abc";
char buf[7]{"111111"};
strlcpy(buf, str, 7);
ASSERT_EQ(buf, {'1', '1', '1', '\0', '\0', '\0', '\0'});
```
On my machine (Debian w/ glibc and clang-16), a `printf` loop over `buf`
gets unrolled into a series of const `printf` at compile-time:
```
printf("%d\n", '1');
printf("%d\n", '1');
printf("%d\n", '1');
printf("%d\n", 0);
printf("%d\n", '1');
printf("%d\n", '1');
printf("%d\n", 0);
```
Seems best to match existing precedent here.
NoumanAmir657
pushed a commit
to NoumanAmir657/llvm-project
that referenced
this pull request
Nov 4, 2024
When running Bionic's testsuite over llvm-libc, tests broke because
e.g.,
```
const char *str = "abc";
char buf[7]{"111111"};
strlcpy(buf, str, 7);
ASSERT_EQ(buf, {'1', '1', '1', '\0', '\0', '\0', '\0'});
```
On my machine (Debian w/ glibc and clang-16), a `printf` loop over `buf`
gets unrolled into a series of const `printf` at compile-time:
```
printf("%d\n", '1');
printf("%d\n", '1');
printf("%d\n", '1');
printf("%d\n", 0);
printf("%d\n", '1');
printf("%d\n", '1');
printf("%d\n", 0);
```
Seems best to match existing precedent here.
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When running Bionic's testsuite over llvm-libc, tests broke because e.g.,
On my machine (Debian w/ glibc and clang-16), a
printfloop overbufgets unrolled into a series of constprintfat compile-time:Seems best to match existing precedent here.