udev: define a generic helper to print messages about unknown users and groups

We cannot just use %m, because strerror returns a confusing error message
for ESRCH or ENOEXEC. udev code was doing a good job, but the error handling
was very verbose. Let's encapsulate the customized error messages in a
helper.

No functional change, except that the error messages have a slightly different
form now. The old messages were a bit better, but we don't have as much
flexibility in the new scheme. "Failed to resolve user 'foo': Unknown user"
should be good enough.

diff --git a/src/basic/user-util.h b/src/basic/user-util.h
index c4f2aea30951f2ad1ab0bdc6ff60f11b657db217..24793530e67f99db3954b2d95c2e1ca52c34b9a1 100644 (file)
--- a/src/basic/user-util.h
+++ b/src/basic/user-util.h
@@ -10,7 +10,8 @@
 
 #include "basic-forward.h"
 
-/* Users managed by systemd-homed. See https://systemd.io/UIDS-GIDS for details how this range fits into the rest of the world */
+/* Users managed by systemd-homed. See https://systemd.io/UIDS-GIDS for details
+ * how this range fits into the rest of the world. */
 #define HOME_UID_MIN ((uid_t) 60001)
 #define HOME_UID_MAX ((uid_t) 60513)
 
@@ -18,6 +19,12 @@
 #define MAP_UID_MIN ((uid_t) 60514)
 #define MAP_UID_MAX ((uid_t) 60577)
 
+/* A helper to print an error message when user or group resolution fails.
+ * Note that we can't use ({ … }) to define a temporary variable, so errnum is
+ * evaluated multiple times. */
+#define STRERROR_USER(errnum) ((errnum) == -ESRCH ? "Unknown user" : (errnum) == -ENOEXEC ? "Not a system user" : STRERROR(errnum))
+#define STRERROR_GROUP(errnum) ((errnum) == -ESRCH ? "Unknown group" : (errnum) == -ENOEXEC ? "Not a system group" : STRERROR(errnum))
+
 bool uid_is_valid(uid_t uid) _const_;
 
 static inline bool gid_is_valid(gid_t gid) {

diff --git a/src/udev/udev-rules.c b/src/udev/udev-rules.c
index 87c57d7487eed409cb25fa653aae218ee0833e8d..543ad9be06c804b4206315202d596ce6d35dd26c 100644 (file)
--- a/src/udev/udev-rules.c
+++ b/src/udev/udev-rules.c
@@ -512,12 +512,10 @@ static int rule_resolve_user(UdevRuleLine *rule_line, const char *name, uid_t *r
         r = userdb_by_name(name, &USERDB_MATCH_ROOT_AND_SYSTEM,
                            USERDB_SUPPRESS_SHADOW | USERDB_PARSE_NUMERIC | USERDB_SYNTHESIZE_NUMERIC,
                            &ur);
-        if (r == -ESRCH)
-                return log_line_error_errno(rule_line, r, "Unknown user '%s', ignoring.", name);
-        if (r == -ENOEXEC)
-                return log_line_error_errno(rule_line, r, "User '%s' is not a system user, ignoring.", name);
         if (r < 0)
-                return log_line_error_errno(rule_line, r, "Failed to resolve user '%s', ignoring: %m", name);
+                return log_line_error_errno(rule_line, r,
+                                            "Failed to resolve user '%s', ignoring: %s",
+                                            name, STRERROR_USER(r));
 
         _cleanup_free_ char *n = strdup(name);
         if (!n)
@@ -549,12 +547,10 @@ static int rule_resolve_group(UdevRuleLine *rule_line, const char *name, gid_t *
         r = groupdb_by_name(name, &USERDB_MATCH_ROOT_AND_SYSTEM,
                             USERDB_SUPPRESS_SHADOW | USERDB_PARSE_NUMERIC | USERDB_SYNTHESIZE_NUMERIC,
                             &gr);
-        if (r == -ESRCH)
-                return log_line_error_errno(rule_line, r, "Unknown group '%s', ignoring.", name);
-        if (r == -ENOEXEC)
-                return log_line_error_errno(rule_line, r, "Group '%s' is not a system group, ignoring.", name);
         if (r < 0)
-                return log_line_error_errno(rule_line, r, "Failed to resolve group '%s', ignoring: %m", name);
+                return log_line_error_errno(rule_line, r,
+                                            "Failed to resolve group '%s', ignoring: %s",
+                                            name, STRERROR_GROUP(r));
 
         _cleanup_free_ char *n = strdup(name);
         if (!n)
@@ -2681,12 +2677,10 @@ static int udev_rule_apply_token_to_event(
                 r = userdb_by_name(owner, &USERDB_MATCH_ROOT_AND_SYSTEM,
                                    USERDB_SUPPRESS_SHADOW | USERDB_PARSE_NUMERIC | USERDB_SYNTHESIZE_NUMERIC,
                                    &ur);
-                if (r == -ESRCH)
-                        log_event_error_errno(event, token, r, "Unknown user \"%s\", ignoring.", owner);
-                else if (r == -ENOEXEC)
-                        log_event_error(event, token, "User \"%s\" is not a system user, ignoring.", owner);
-                else if (r < 0)
-                        log_event_error_errno(event, token, r, "Failed to resolve user \"%s\", ignoring: %m", owner);
+                if (r < 0)
+                        log_event_error_errno(event, token, r,
+                                              "Failed to resolve user \"%s\", ignoring: %s",
+                                              owner, STRERROR_USER(r));
                 else {
                         event->uid = ur->uid;
                         log_event_debug(event, token, "Set owner: %s("UID_FMT")", owner, event->uid);
@@ -2709,12 +2703,10 @@ static int udev_rule_apply_token_to_event(
                 r = groupdb_by_name(group, &USERDB_MATCH_ROOT_AND_SYSTEM,
                                     USERDB_SUPPRESS_SHADOW | USERDB_PARSE_NUMERIC | USERDB_SYNTHESIZE_NUMERIC,
                                     &gr);
-                if (r == -ESRCH)
-                        log_event_error_errno(event, token, r, "Unknown group \"%s\", ignoring.", group);
-                else if (r == -ENOEXEC)
-                        log_event_error(event, token, "Group \"%s\" is not a system group, ignoring.", group);
-                else if (r < 0)
-                        log_event_error_errno(event, token, r, "Failed to resolve group \"%s\", ignoring: %m", group);
+                if (r < 0)
+                        log_event_error_errno(event, token, r,
+                                              "Failed to resolve group \"%s\", ignoring: %s",
+                                              group, STRERROR_GROUP(r));
                 else {
                         event->gid = gr->gid;
                         log_event_debug(event, token, "Set group: %s("GID_FMT")", group, event->gid);

diff --git a/test/units/TEST-17-UDEV.verify.sh b/test/units/TEST-17-UDEV.verify.sh
index 8252b630d3538afbedb87e54f19d330cd3a223c8..5b6baa428029d1e7d947027c101a8ec3e559d3e8 100755 (executable)
--- a/test/units/TEST-17-UDEV.verify.sh
+++ b/test/units/TEST-17-UDEV.verify.sh
@@ -309,15 +309,15 @@ assert_0 "${rules}"
 test_syntax_error 'OWNER=":nosuchuser:"' "Failed to resolve user ':nosuchuser:', ignoring: Invalid argument"
 # nonexistent user
 if ! getent passwd nosuchuser >/dev/null; then
-    test_syntax_error 'OWNER="nosuchuser"' "Unknown user 'nosuchuser', ignoring."
+    test_syntax_error 'OWNER="nosuchuser"' "Failed to resolve user 'nosuchuser', ignoring: Unknown user"
 fi
 if ! getent passwd 12345 >/dev/null; then
-    test_syntax_error 'OWNER="12345"' "Unknown user '12345', ignoring."
+    test_syntax_error 'OWNER="12345"' "Failed to resolve user '12345', ignoring: Unknown user"
 fi
 # regular user
 if getent passwd testuser >/dev/null; then
-    test_syntax_error 'OWNER="testuser"' "User 'testuser' is not a system user, ignoring."
-    test_syntax_error "OWNER=\"$(id -u testuser)\"" "User '$(id -u testuser)' is not a system user, ignoring."
+    test_syntax_error 'OWNER="testuser"' "Failed to resolve user 'testuser', ignoring: Not a system user"
+    test_syntax_error "OWNER=\"$(id -u testuser)\"" "Failed to resolve user '$(id -u testuser)', ignoring: Not a system user"
 fi
 test_syntax_error 'GROUP{a}="b"' 'Invalid attribute for GROUP.'
 test_syntax_error 'GROUP-="b"' 'Invalid operator for GROUP.'
@@ -341,15 +341,15 @@ assert_0 "${rules}"
 test_syntax_error 'GROUP=":nosuchgroup:"' "Failed to resolve group ':nosuchgroup:', ignoring: Invalid argument"
 # nonexistent group
 if ! getent group nosuchgroup >/dev/null; then
-    test_syntax_error 'GROUP="nosuchgroup"' "Unknown group 'nosuchgroup', ignoring."
+    test_syntax_error 'GROUP="nosuchgroup"' "Failed to resolve group 'nosuchgroup', ignoring: Unknown group"
 fi
 if ! getent group 12345 >/dev/null; then
-    test_syntax_error 'GROUP="12345"' "Unknown group '12345', ignoring."
+    test_syntax_error 'GROUP="12345"' "Failed to resolve group '12345', ignoring: Unknown group"
 fi
 # regular group
 if getent group testuser >/dev/null; then
-    test_syntax_error 'GROUP="testuser"' "Group 'testuser' is not a system group, ignoring."
-    test_syntax_error "GROUP=\"$(id -g testuser)\"" "Group '$(id -g testuser)' is not a system group, ignoring."
+    test_syntax_error 'GROUP="testuser"' "Failed to resolve group 'testuser', ignoring: Not a system group"
+    test_syntax_error "GROUP=\"$(id -g testuser)\"" "Failed to resolve group '$(id -g testuser)', ignoring: Not a system group"
 fi
 test_syntax_error 'MODE{a}="b"' 'Invalid attribute for MODE.'
 test_syntax_error 'MODE-="b"' 'Invalid operator for MODE.'