From 2d5e138e8c28e89fea8e3e960ca863787bb6fe91 Mon Sep 17 00:00:00 2001 From: =?utf8?q?Thomas=20Wei=C3=9Fschuh?= Date: Thu, 5 Oct 2023 13:19:14 +0200 Subject: [PATCH] libmount: add helper to log mount messages as emitted by kernel MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit The kernel helpfully provides feedback about failed operations via the filesystem descriptor. Read that information and expose it via libmounts debug facilities. Signed-off-by: Thomas Weißschuh --- libmount/src/hook_mount.c | 25 +++++++++++++++++++++++++ 1 file changed, 25 insertions(+) diff --git a/libmount/src/hook_mount.c b/libmount/src/hook_mount.c index 4b2a534f74..2e0b5f0fac 100644 --- a/libmount/src/hook_mount.c +++ b/libmount/src/hook_mount.c @@ -64,6 +64,31 @@ static void close_sysapi_fds(struct libmnt_sysapi *api) api->fd_tree = api->fd_fs = -1; } +static void debug_fs_fd_messages(int fd) +{ + uint8_t buf[BUFSIZ]; + int rc; + + while ((rc = read(fd, buf, sizeof(buf))) != -1) { + if (rc > 0 && buf[rc - 1] == '\n') + buf[rc - 1] = '\0'; + DBG(CXT, ul_debug("message from kernel: %*s", rc, buf)); + } +} + +static void set_syscall_status_cxt_log(struct libmnt_context *cxt, + const char *name, int x) +{ + struct libmnt_sysapi *api; + + set_syscall_status(cxt, name, x); + + if (!x) { + api = get_sysapi(cxt); + debug_fs_fd_messages(api->fd_fs); + } +} + /* * This hookset uses 'struct libmnt_sysapi' (mountP.h) as hookset data. */ -- 2.47.2