On 7/16/25 13:27, Ján Tomko wrote: > On a Friday in 2025, Michal Privoznik via Devel wrote: >> From: Michal Privoznik <mpriv...@redhat.com> >> >> Currently, when somebody wants to debug the NSS plugin, they have >> to change a line in libvirt_nss.h (to enable debug printings) and >> recompile the module. This may work for us, developers, but we >> can not expect this from users. >> >> For now, this turns debug printings unconditionally on. Making it >> conditional on an envvar is handled in the next commit. >> >> Signed-off-by: Michal Privoznik <mpriv...@redhat.com> >> --- >> build-aux/syntax-check.mk | 2 +- >> tools/nss/libvirt_nss.h | 30 +-------------- >> tools/nss/libvirt_nss_log.c | 76 +++++++++++++++++++++++++++++++++++++ >> tools/nss/libvirt_nss_log.h | 38 +++++++++++++++++++ >> tools/nss/meson.build | 1 + >> 5 files changed, 117 insertions(+), 30 deletions(-) >> create mode 100644 tools/nss/libvirt_nss_log.c >> create mode 100644 tools/nss/libvirt_nss_log.h >> >> diff --git a/tools/nss/libvirt_nss_log.c b/tools/nss/libvirt_nss_log.c >> new file mode 100644 >> index 0000000000..0863897c07 >> --- /dev/null >> +++ b/tools/nss/libvirt_nss_log.c >> @@ -0,0 +1,76 @@ >> +/* >> + * libvirt_nss_log: Logging for Name Service Switch plugin >> + * >> + * Copyright (C) 2025 Red Hat, Inc. >> + * > >> + * This 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. >> + * >> + * This 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 this library. If not, see >> + * <http://www.gnu.org/licenses/>. > > Can we replace this with just: > SPDX-License-Identifier: LGPL-2.1-or-later > >> + */ >> + >> +#include <config.h> >> + >> +#include <errno.h> >> +#include <stdio.h> >> +#include <string.h> >> +#include <stdarg.h> >> + >> +#include "libvirt_nss_log.h" >> +#include "libvirt_nss.h" >> + >> +#define NULLSTR(s) ((s) ? (s) : "<null>") >> + >> +static const char * __attribute__((returns_nonnull)) >> +nssLogPriorityToString(nssLogPriority prio) >> +{ >> + switch (prio) { >> + case NSS_DEBUG: >> + return "DEBUG"; >> + case NSS_ERROR: >> + return "ERROR"; >> + } >> + >> + return ""; >> +} >> + >> +void >> +nssLog(nssLogPriority prio, >> + const char *func, >> + int linenr, >> + const char *fmt, ...) >> +{ >> + int saved_errno = errno; >> + const size_t ebuf_size = 512; >> + g_autofree char *ebuf = NULL; >> + va_list ap; >> + >> + fprintf(stderr, "%s %s:%d : ", nssLogPriorityToString(prio), >> func, linenr); >> + >> + va_start(ap, fmt); >> + vfprintf(stderr, fmt, ap); >> + va_end(ap); >> + >> + switch (prio) { >> + case NSS_DEBUG: >> + break; >> + >> + case NSS_ERROR: >> + ebuf = calloc(ebuf_size, sizeof(*ebuf)); >> + if (ebuf) >> + strerror_r(saved_errno, ebuf, ebuf_size); > > clang complains: > ../../work/libvirt/tools/nss/libvirt_nss_log.c:79:13: error: ignoring > return value of function declared with 'warn_unused_result' attribute [- > Werror,-Wunused-result] > 79 | strerror_r(saved_errno, ebuf, ebuf_size); > | ^~~~~~~~~~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~ >
Ah, gcc complains too. But only after I turn on optimizations (by default I compile as 'meson setup --optimization=0 ...' so that I'm able to gdb/valgrind the thing). I can't help but wonder why unused-result depends on optimizations. > It seems we're building with GNU_SOURCE, so we should print the char* > returned by the function; not our allocated buffer. which wouldn't fly on FreeBSD where are no GNU extensions. Le sigh. Fortunately, we do not need GNU_SOURCE for this. Michal
