[PATCH v2] string: Add tests for unique strerror error strings
Arjun Shankar
arjun@redhat.com
Thu Sep 11 10:58:58 GMT 2025
strerror and its variants should return unique strings for each
known/unknown error. Add tests to verify this for strerror, strerror_r
and strerror_l (for the C locale).
strerror_r is special in that the GNU variant returns "Unknown error"
strings (and only those) in the user supplied buffer, returning
read-only internal strings for known errors. Additionally test for this
as well.
---
v1: https://inbox.sourceware.org/libc-alpha/20250910232934.226719-1-arjun@redhat.com/
Changes in v2:
* Address Florian's comments, making the tests Linux specific and using
memory allocation with consistency.
---
sysdeps/unix/sysv/linux/Makefile | 8 ++
.../unix/sysv/linux/tst-strerror-strings.c | 79 +++++++++++++++++++
.../unix/sysv/linux/tst-strerror_l-strings.c | 40 ++++++++++
.../unix/sysv/linux/tst-strerror_r-strings.c | 43 ++++++++++
4 files changed, 170 insertions(+)
create mode 100644 sysdeps/unix/sysv/linux/tst-strerror-strings.c
create mode 100644 sysdeps/unix/sysv/linux/tst-strerror_l-strings.c
create mode 100644 sysdeps/unix/sysv/linux/tst-strerror_r-strings.c
diff --git a/sysdeps/unix/sysv/linux/Makefile b/sysdeps/unix/sysv/linux/Makefile
index 2c5bf42236..7de7299ce4 100644
--- a/sysdeps/unix/sysv/linux/Makefile
+++ b/sysdeps/unix/sysv/linux/Makefile
@@ -716,3 +716,11 @@ tests-static += \
tst-rseq-nptl-static \
# tests-static
endif
+
+ifeq ($(subdir),string)
+tests += \
+ tst-strerror-strings \
+ tst-strerror_l-strings \
+ tst-strerror_r-strings \
+ # tests
+endif
diff --git a/sysdeps/unix/sysv/linux/tst-strerror-strings.c b/sysdeps/unix/sysv/linux/tst-strerror-strings.c
new file mode 100644
index 0000000000..ae9c12f377
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/tst-strerror-strings.c
@@ -0,0 +1,79 @@
+/* Test that strerror variants return unique strings for each errnum.
+
+ Copyright (C) 2025 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <https://www.gnu.org/licenses/>. */
+
+#include <string.h>
+#include <stdlib.h>
+
+#include <support/support.h>
+#include <support/check.h>
+
+static int
+compare_strings (const void *a, const void *b)
+{
+ const char *stra = * (const char **) a;
+ const char *strb = * (const char **) b;
+
+ int ret = strcmp (stra, strb);
+
+ if (!ret)
+ FAIL_EXIT1 ("Found duplicate error strings: \"%s\"\n", stra);
+
+ return ret;
+}
+
+#define NSTRINGS 2049
+
+static int
+do_test (void)
+{
+ char *string[NSTRINGS];
+ /* Convenient indexing for error strings from -1024 to 1024. */
+ char **err_str = string + 1024;
+
+ unsetenv ("LANGUAGE");
+
+ xsetlocale (LC_ALL, "C");
+
+ for (int i = -1024; i <= 1024; i++)
+ {
+
+#ifdef TEST_STRERROR_VARIANT
+ /* Used for testing strerror_r and strerror_l. */
+ err_str[i] = TEST_STRERROR_VARIANT (i);
+#else
+ err_str[i] = xstrdup (strerror (i));
+#endif
+
+ /* Negative as well as large positive errnums are unused. 160 allows
+ us to define more errors without needing to update this test. */
+ int is_unknown_error
+ = (strstr (err_str[i], "Unknown error ") == err_str[i]);
+ TEST_VERIFY_EXIT ((i >= 0 && i < 160) || is_unknown_error);
+ }
+
+ /* We check for and fail on duplicate strings in the comparator. */
+ qsort (string, NSTRINGS, sizeof (char *), compare_strings);
+
+ for (int i = -1024; i <= 1024; i++)
+ free (err_str[i]);
+
+ return 0;
+}
+
+#include <support/test-driver.c>
diff --git a/sysdeps/unix/sysv/linux/tst-strerror_l-strings.c b/sysdeps/unix/sysv/linux/tst-strerror_l-strings.c
new file mode 100644
index 0000000000..65c5a2f08c
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/tst-strerror_l-strings.c
@@ -0,0 +1,40 @@
+/* Test that strerror_l returns unique strings for each errnum.
+
+ Copyright (C) 2025 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <https://www.gnu.org/licenses/>. */
+
+#include <stdlib.h>
+#include <string.h>
+#include <support/support.h>
+#include <support/check.h>
+
+/* newlocale returns (locale_t) 0 upon error, so it makes for a good initial
+ value that is different from any valid locale_t. */
+static locale_t loc = (locale_t) 0;
+
+/* Wrap strerror_l to be plugged into the equivalent strerror test. */
+static char *
+wrap_strerror_l (int errnum)
+{
+ if (loc == (locale_t) 0)
+ loc = xnewlocale (LC_ALL_MASK, "C", (locale_t) 0);
+
+ return xstrdup (strerror_l (errnum, loc));
+}
+
+#define TEST_STRERROR_VARIANT wrap_strerror_l
+#include "tst-strerror-strings.c"
diff --git a/sysdeps/unix/sysv/linux/tst-strerror_r-strings.c b/sysdeps/unix/sysv/linux/tst-strerror_r-strings.c
new file mode 100644
index 0000000000..dea9415eb8
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/tst-strerror_r-strings.c
@@ -0,0 +1,43 @@
+/* Test that GNU strerror_r returns unique strings for each errnum.
+
+ Copyright (C) 2025 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <https://www.gnu.org/licenses/>. */
+
+#include <string.h>
+#include <support/support.h>
+#include <support/check.h>
+
+/* Wrap strerror_r into a checked variant that can be plugged into the
+ equivalent strerror test. */
+static char *
+test_and_return_strerror_r (int errnum)
+{
+ char buf[1024];
+
+ char *ret = strerror_r (errnum, buf, sizeof (buf));
+
+ /* User supplied buffer used for and only for "Unknown error" strings. */
+ if (strstr (ret, "Unknown error ") == ret)
+ TEST_VERIFY_EXIT (ret == buf);
+ else
+ TEST_VERIFY_EXIT (ret != buf);
+
+ return xstrdup (ret);
+}
+
+#define TEST_STRERROR_VARIANT test_and_return_strerror_r
+#include "tst-strerror-strings.c"
--
2.50.1
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