libc fortify: error on realpath(NULL, foo)
I've half a mind to make this a warning instead, since this sort of
call isn't UB. That said:
- if the user really wants this (I can't imagine why they would), they
can just put NULL in a non-const variable,
- we're slowly moving to -Werror ~everywhere anyway, and
- it's presumably easier to change this from an error to a warning than
the other way around
Bug: 12231437
Test: m checkbuild on bullhead internal master. No new
CtsBionicTestCases failures.
Change-Id: Ie8bf5a3455f663686fda4a7450fb35d147fa745e
diff --git a/libc/include/bits/fortify/stdlib.h b/libc/include/bits/fortify/stdlib.h
index cf4b7ea..8f3b02c 100644
--- a/libc/include/bits/fortify/stdlib.h
+++ b/libc/include/bits/fortify/stdlib.h
@@ -40,7 +40,8 @@
#if defined(__clang__)
char* realpath(const char* path, char* resolved)
__clang_error_if(__bos(resolved) != __BIONIC_FORTIFY_UNKNOWN_SIZE &&
- __bos(resolved) < __PATH_MAX, __realpath_buf_too_small_str);
+ __bos(resolved) < __PATH_MAX, __realpath_buf_too_small_str)
+ __clang_error_if(!path, "'realpath': NULL path is never correct; flipped arguments?");
/* No need for a definition; the only issues we can catch are at compile-time. */
#else /* defined(__clang__) */
diff --git a/tests/fortify_compilation_test.cpp b/tests/fortify_compilation_test.cpp
index d859ef1..7517fde 100644
--- a/tests/fortify_compilation_test.cpp
+++ b/tests/fortify_compilation_test.cpp
@@ -376,6 +376,7 @@
// This is fine.
realpath(".", NULL);
- // FIXME: But we should warn on this.
- realpath(NULL, buf);
+ char bigbuf[PATH_MAX];
+ // CLANG: error: 'realpath': NULL path is never correct; flipped arguments?
+ realpath(NULL, bigbuf);
}
diff --git a/tests/stdlib_test.cpp b/tests/stdlib_test.cpp
index c724f74..7d2dc20 100644
--- a/tests/stdlib_test.cpp
+++ b/tests/stdlib_test.cpp
@@ -184,7 +184,9 @@
TEST(stdlib, realpath__NULL_filename) {
errno = 0;
- char* p = realpath(NULL, NULL);
+ // Work around the compile-time error generated by FORTIFY here.
+ const char* path = NULL;
+ char* p = realpath(path, NULL);
ASSERT_TRUE(p == NULL);
ASSERT_EQ(EINVAL, errno);
}