Merge branch 'PR/libmount-errmsg' of github.com:karelzak/util-linux-work

* 'PR/libmount-errmsg' of github.com:karelzak/util-linux-work:
  libmount: (loop) detect and report lost loop nodes
  libmount: add mnt_context_sprintf_errmsg()
  libmount: add functions to use error buffer
  libmount: use regular function to save/reset syscalls status

libmount/src/context.c

@@ -41,6 +41,7 @@
 #include "namespace.h"
 #include "match.h"
 
+#include <stdarg.h>
 #include <sys/wait.h>
 
 /**
@@ -314,7 +315,7 @@ int mnt_context_reset_status(struct libmnt_context *cxt)
 	if (!cxt)
 		return -EINVAL;
 
-	reset_syscall_status(cxt);
+	mnt_context_syscall_reset_status(cxt);
 
 	cxt->syscall_status = 1;		/* means not called yet */
 	cxt->helper_exec_status = 1;
@@ -2599,8 +2600,8 @@ int mnt_context_get_syscall_errno(struct libmnt_context *cxt)
  *
  * The @status should be 0 on success, or negative number on error (-errno).
  *
- * This function should only be used if the [u]mount(2) syscall is NOT called by
- * libmount code.
+ * This function is intended for cases where mount/umount is called externally,
+ * rather than by libmount.
  *
  * Returns: 0 or negative number in case of error.
  */
@@ -2614,6 +2615,77 @@ int mnt_context_set_syscall_status(struct libmnt_context *cxt, int status)
 	return 0;
 }
 
+/* Use this for syscalls called from libmount */
+void mnt_context_syscall_save_status(	struct libmnt_context *cxt,
+					const char *syscallname,
+					int success)
+{
+	if (!success) {
+		DBG(CXT, ul_debug("syscall '%s' [failed: %m]", syscallname));
+		cxt->syscall_status = -errno;
+		cxt->syscall_name = syscallname;
+	} else {
+		DBG(CXT, ul_debug("syscall '%s' [success]", syscallname));
+		cxt->syscall_status = 0;
+	}
+}
+
+void mnt_context_syscall_reset_status(struct libmnt_context *cxt)
+{
+	DBG(CXT, ul_debug("reset syscall status"));
+	cxt->syscall_status = 0;
+	cxt->syscall_name = NULL;
+
+	free(cxt->errmsg);
+	cxt->errmsg = NULL;
+}
+
+int mnt_context_set_errmsg(struct libmnt_context *cxt, const char *msg)
+{
+	char *p = NULL;
+
+	if (msg) {
+		p = strdup(msg);
+		if (!p)
+			return -ENOMEM;
+	}
+
+	free(cxt->errmsg);
+	cxt->errmsg = p;
+
+	return 0;
+}
+
+int mnt_context_append_errmsg(struct libmnt_context *cxt, const char *msg)
+{
+	if (cxt->errmsg) {
+		int rc = strappend(&cxt->errmsg, "; ");
+		if (rc)
+			return rc;
+	}
+
+	return strappend(&cxt->errmsg, msg);
+}
+
+int mnt_context_sprintf_errmsg(struct libmnt_context *cxt, const char *msg, ...)
+{
+	int rc;
+	va_list ap;
+	char *p = NULL;
+
+	va_start(ap, msg);
+	rc = vasprintf(&p, msg, ap);
+	va_end(ap);
+
+	if (rc < 0 || !p)
+		return rc;
+
+	free(cxt->errmsg);
+	cxt->errmsg = p;
+
+	return 0;
+}
+
 /**
  * mnt_context_strerror
  * @cxt: context

libmount/src/context_mount.c

@@ -1433,6 +1433,11 @@ int mnt_context_get_mount_excode(
 	mnt_context_get_user_mflags(cxt, &uflags);	/* userspace flags */
 
 	if (!mnt_context_syscall_called(cxt)) {
+		if (buf && cxt->errmsg) {
+			xstrncpy(buf, cxt->errmsg, bufsz);
+			return MNT_EX_USAGE;
+		}
+
 		/*
 		 * libmount errors (extra library checks)
 		 */
@@ -1572,10 +1577,13 @@ int mnt_context_get_mount_excode(
 	 */
 	syserr = mnt_context_get_syscall_errno(cxt);
 
-	if (buf && cxt->syscall_errmsg) {
-		snprintf(buf, bufsz, _("%s system call failed: %s"),
-					cxt->syscall_name ? : "mount",
-					cxt->syscall_errmsg);
+	if (buf && cxt->errmsg) {
+		if (cxt->syscall_name)
+			snprintf(buf, bufsz, _("%s system call failed: %s"),
+					cxt->syscall_name, cxt->errmsg);
+		else
+			xstrncpy(buf, cxt->errmsg, bufsz);
+
 		return MNT_EX_FAIL;
 	}
 

libmount/src/hook_loopdev.c

@@ -277,6 +277,14 @@ static int setup_loopdev(struct libmnt_context *cxt,
 		goto done_no_deinit;
 	if (mnt_opt_has_value(loopopt)) {
 		rc = loopcxt_set_device(&lc, mnt_opt_get_value(loopopt));
+		if (rc == 0 && loopcxt_is_lost(&lc)) {
+			DBG(LOOP, ul_debugobj(cxt, "node lost"));
+
+			dev_t devno = loopcxt_get_devno(&lc);
+			mnt_context_sprintf_errmsg(cxt, _("device node %s (%u:%u) is lost"),
+					loopcxt_get_device(&lc), major(devno), minor(devno));
+			rc = -EINVAL;
+		}
 		if (rc == 0)
 			loopdev = loopcxt_get_device(&lc);
 	}

libmount/src/hook_mount.c

@@ -70,8 +70,7 @@ static void save_fd_messages(struct libmnt_context *cxt, int fd)
 	uint8_t buf[BUFSIZ];
 	int rc;
 
-	free(cxt->syscall_errmsg);
-	cxt->syscall_errmsg = NULL;
+	mnt_context_set_errmsg(cxt, NULL);
 
 	while ((rc = read(fd, buf, sizeof(buf))) != -1) {
 		if (rc > 0 && buf[rc - 1] == '\n')
@@ -80,10 +79,7 @@ static void save_fd_messages(struct libmnt_context *cxt, int fd)
 
 		if (rc < 3 || strncmp((char *) buf, "e ", 2) != 0)
 			continue;
-		if (cxt->syscall_errmsg)
-			strappend(&cxt->syscall_errmsg, "; ");
-
-		strappend(&cxt->syscall_errmsg, ((char *) buf) + 2);
+		mnt_context_append_errmsg(cxt, ((char *) buf) + 2);
 	}
 }
 
@@ -92,7 +88,7 @@ static void hookset_set_syscall_status(struct libmnt_context *cxt,
 {
 	struct libmnt_sysapi *api;
 
-	set_syscall_status(cxt, name, x);
+	mnt_context_syscall_save_status(cxt, name, x);
 
 	if (!x) {
 		api = get_sysapi(cxt);
@@ -819,7 +815,7 @@ static int hook_prepare(struct libmnt_context *cxt,
 	/* we need to recover from this error, so hook_mount_legacy.c
 	 * can try to continue */
 	DBG(HOOK, ul_debugobj(hs, "failed to init new API"));
-	reset_syscall_status(cxt);
+	mnt_context_syscall_reset_status(cxt);
 	hookset_deinit(cxt, hs);
 	return 1;
 }

libmount/src/hook_mount_legacy.c

@@ -76,10 +76,8 @@ static int hook_propagation(struct libmnt_context *cxt,
 
 	if (rc) {
 		/* Update global syscall status if only this function called */
-		if (mnt_context_propagation_only(cxt)) {
-			cxt->syscall_status = -errno;
-			cxt->syscall_name = "mount";
-		}
+		if (mnt_context_propagation_only(cxt))
+			mnt_context_syscall_save_status(cxt, "mount", rc == 0);
 
 		DBG(HOOK, ul_debugobj(hs, "  mount(2) failed [errno=%d %m]", errno));
 		rc = -MNT_ERR_APPLYFLAGS;
@@ -240,10 +238,7 @@ static int hook_mount(struct libmnt_context *cxt,
 			  options : "<none>"));
 
 	if (mount(src, target, type, flags, options)) {
-		cxt->syscall_status = -errno;
-		cxt->syscall_name = "mount";
-		DBG(HOOK, ul_debugobj(hs, "  mount(2) failed [errno=%d %m]",
-					-cxt->syscall_status));
+		mnt_context_syscall_save_status(cxt, "mount", 0);
 		rc = -cxt->syscall_status;
 		return rc;
 	}

libmount/src/hook_subdir.c

@@ -189,7 +189,7 @@ static int do_mount_subdir(
 		DBG(HOOK, ul_debug("attach subdir  %s", subdir));
 		fd = open_tree(api->fd_tree, subdir,
 					OPEN_TREE_CLOEXEC | OPEN_TREE_CLONE);
-		set_syscall_status(cxt, "open_tree", fd >= 0);
+		mnt_context_syscall_save_status(cxt, "open_tree", fd >= 0);
 		if (fd < 0)
 			rc = -errno;
 
@@ -201,7 +201,7 @@ static int do_mount_subdir(
 			setns(hsd->old_ns_fd, CLONE_NEWNS);
 
 			rc = move_mount(fd, "", AT_FDCWD, target, MOVE_MOUNT_F_EMPTY_PATH);
-			set_syscall_status(cxt, "move_mount", rc == 0);
+			mnt_context_syscall_save_status(cxt, "move_mount", rc == 0);
 			if (rc)
 				rc = -errno;
 
@@ -223,8 +223,7 @@ static int do_mount_subdir(
 		/* Classic mount(2) based way */
 		DBG(HOOK, ul_debug("mount subdir %s to %s", src, target));
 		rc = mount(src, target, NULL, MS_BIND, NULL);
-
-		set_syscall_status(cxt, "mount", rc == 0);
+		mnt_context_syscall_save_status(cxt, "mount", rc == 0);
 		if (rc)
 			rc = -errno;
 		free(src);
@@ -233,7 +232,7 @@ static int do_mount_subdir(
 	if (!rc) {
 		DBG(HOOK, ul_debug("umount old root %s", root));
 		rc = umount(root);
-		set_syscall_status(cxt, "umount", rc == 0);
+		mnt_context_syscall_save_status(cxt, "umount", rc == 0);
 		if (rc)
 			rc = -errno;
 		hsd->tmp_umounted = 1;

libmount/src/mountP.h

@@ -432,7 +432,7 @@ struct libmnt_context
 
 	int	syscall_status;	/* 1: not called yet, 0: success, <0: -errno */
 	const char *syscall_name;	/* failed syscall name */
-	char	*syscall_errmsg;	/* message from kernel */
+	char	*errmsg;	/* library or kernel message */
 
 	struct libmnt_ns	ns_orig;	/* original namespace */
 	struct libmnt_ns	ns_tgt;		/* target namespace */
@@ -480,27 +480,6 @@ struct libmnt_context
 /* Flags usable with MS_BIND|MS_REMOUNT */
 #define MNT_BIND_SETTABLE	(MS_NOSUID|MS_NODEV|MS_NOEXEC|MS_NOATIME|MS_NODIRATIME|MS_RELATIME|MS_RDONLY|MS_NOSYMFOLLOW)
 
-static inline void set_syscall_status(struct libmnt_context *cxt, const char *name, int x)
-{
-	if (!x) {
-		DBG(CXT, ul_debug("syscall '%s' [%m]", name));
-		cxt->syscall_status = -errno;
-		cxt->syscall_name = name;
-	} else {
-		DBG(CXT, ul_debug("syscall '%s' [success]", name));
-		cxt->syscall_status = 0;
-	}
-}
-
-static inline void reset_syscall_status(struct libmnt_context *cxt)
-{
-	DBG(CXT, ul_debug("reset syscall status"));
-	cxt->syscall_status = 0;
-	cxt->syscall_name = NULL;
-
-	free(cxt->syscall_errmsg);
-	cxt->syscall_errmsg = NULL;
-}
 
 /* optmap.c */
 extern const struct libmnt_optmap *mnt_optmap_get_entry(
@@ -621,6 +600,10 @@ extern int __mnt_fs_set_target_ptr(struct libmnt_fs *fs, char *tgt)
 			__attribute__((nonnull(1)));
 
 /* context.c */
+extern void mnt_context_syscall_save_status(struct libmnt_context *cxt,
+                                        const char *syscallname, int success);
+extern void mnt_context_syscall_reset_status(struct libmnt_context *cxt);
+
 extern struct libmnt_context *mnt_copy_context(struct libmnt_context *o);
 extern int mnt_context_utab_writable(struct libmnt_context *cxt);
 extern const char *mnt_context_get_writable_tabpath(struct libmnt_context *cxt);
@@ -643,6 +626,10 @@ extern int mnt_context_update_tabs(struct libmnt_context *cxt);
 extern int mnt_context_umount_setopt(struct libmnt_context *cxt, int c, char *arg);
 extern int mnt_context_mount_setopt(struct libmnt_context *cxt, int c, char *arg);
 
+extern int mnt_context_set_errmsg(struct libmnt_context *cxt, const char *msg);
+extern int mnt_context_append_errmsg(struct libmnt_context *cxt, const char *msg);
+extern int mnt_context_sprintf_errmsg(struct libmnt_context *cxt, const char *msg, ...);
+
 extern int mnt_context_propagation_only(struct libmnt_context *cxt)
 			__attribute__((nonnull));