On Thu, Apr 02, 2026 at 09:45:41AM +0800, Chunyu Hu wrote: > 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]>
LGTM, so: Reviewed-by: Lorenzo Stoakes <[email protected]> > --- > Changes in v8: > - go back to ksft_exit_fail_msg in the two error exit path as no clean > ksft_exit_fail_perror that supports va_list > 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 | 15 ++++++++++++--- > 1 file changed, 12 insertions(+), 3 deletions(-) > > diff --git a/tools/testing/selftests/mm/vm_util.c > b/tools/testing/selftests/mm/vm_util.c > index ad96d19d1b85..db94564f4431 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)); > > 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_msg("%s write(%.*s) failed: %s\n", path, > (int)(buflen - 1), > + buf, strerror(errno)); > + 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 >
