Add three more checks for buflen and numwritten. The buflen should be at least two, that means at least one char and the null-end. The error case check is added by checking numwriten < 0 instead of numwritten < 1. And the truncate case is checked. The test will exit if any of these conditions aren't met.
Additionally, add more print information when a write failure occurs or a truncated write happens, providing clearer diagnostics. Signed-off-by: Chunyu Hu <[email protected]> --- Changes in v7: - add an empty line before the 'buflen < 1' line. And change to 'buflen < 2 to limit the buflen at least to be 2, so at least one char is allowed. - handle the numwriten < 0 case, which is the error path. - use ksft_exit_fail_perror in error exit path. - use %.*s to print the buf when error happened Changes in v6: - save/restore errno before and after the close(), so the log could show the correct error info on failure. Suggested by AI. Chagnes in v5: - new patch for making improve on write_file. Add more safety checks and diagnostics info in log --- tools/testing/selftests/mm/vm_util.c | 17 +++++++++++++---- 1 file changed, 13 insertions(+), 4 deletions(-) diff --git a/tools/testing/selftests/mm/vm_util.c b/tools/testing/selftests/mm/vm_util.c index ad96d19d1b85..00aaf33387f5 100644 --- a/tools/testing/selftests/mm/vm_util.c +++ b/tools/testing/selftests/mm/vm_util.c @@ -767,15 +767,24 @@ int unpoison_memory(unsigned long pfn) void write_file(const char *path, const char *buf, size_t buflen) { - int fd; + int fd, saved_errno; ssize_t numwritten; + if (buflen < 2) + ksft_exit_fail_msg("Incorrect buffer len: %zu\n", buflen); + fd = open(path, O_WRONLY); if (fd == -1) - ksft_exit_fail_msg("%s open failed: %s\n", path, strerror(errno)); + ksft_exit_fail_perror("%s open failed", path); numwritten = write(fd, buf, buflen - 1); + saved_errno = errno; close(fd); - if (numwritten < 1) - ksft_exit_fail_msg("Write failed\n"); + errno = saved_errno; + if (numwritten < 0) + ksft_exit_fail_perror("%s write(%.*s) failed", path, (int)(buflen - 1), + buf); + if (numwritten != buflen - 1) + ksft_exit_fail_msg("%s write(%.*s) is truncated, expected %zu bytes, got %zd bytes\n", + path, (int)(buflen - 1), buf, buflen - 1, numwritten); } -- 2.53.0
