From a4562f945d2386f9f089f16f67463b9b38e78957 Mon Sep 17 00:00:00 2001
From: Lennart Poettering <lennart@poettering.net>
Date: Tue, 19 Dec 2023 15:01:36 +0100
Subject: [PATCH] varlink: add helper that turns varlink errors back to errnos,
 client-side

---
 src/shared/varlink.c | 39 +++++++++++++++++++++++++++++++++++++++
 src/shared/varlink.h |  2 ++
 2 files changed, 41 insertions(+)

diff --git a/src/shared/varlink.c b/src/shared/varlink.c
index 84497c1a06..f9c7f2e659 100644
--- a/src/shared/varlink.c
+++ b/src/shared/varlink.c
@@ -3997,3 +3997,42 @@ int varlink_invocation(VarlinkInvocationFlags flags) {
 
         return true;
 }
+
+int varlink_error_to_errno(const char *error, JsonVariant *parameters) {
+        static const struct {
+                const char *error;
+                int value;
+        } table[] = {
+                { VARLINK_ERROR_DISCONNECTED,           -ECONNRESET    },
+                { VARLINK_ERROR_TIMEOUT,                -ETIMEDOUT     },
+                { VARLINK_ERROR_PROTOCOL,               -EPROTO        },
+                { VARLINK_ERROR_INTERFACE_NOT_FOUND,    -EADDRNOTAVAIL },
+                { VARLINK_ERROR_METHOD_NOT_FOUND,       -ENXIO         },
+                { VARLINK_ERROR_METHOD_NOT_IMPLEMENTED, -ENOTTY        },
+                { VARLINK_ERROR_INVALID_PARAMETER,      -EINVAL        },
+                { VARLINK_ERROR_PERMISSION_DENIED,      -EACCES        },
+                { VARLINK_ERROR_EXPECTED_MORE,          -EBADE         },
+        };
+
+        if (!error)
+                return 0;
+
+        FOREACH_ARRAY(t, table, ELEMENTSOF(table))
+                if (streq(error, t->error))
+                        return t->value;
+
+        if (streq(error, VARLINK_ERROR_SYSTEM) && parameters) {
+                JsonVariant *e;
+
+                e = json_variant_by_key(parameters, "errno");
+                if (json_variant_is_integer(e)) {
+                        int64_t i;
+
+                        i = json_variant_integer(e);
+                        if (i > 0 && i < ERRNO_MAX)
+                                return -i;
+                }
+        }
+
+        return -EBADR; /* Catch-all */
+}
diff --git a/src/shared/varlink.h b/src/shared/varlink.h
index 418ba49d1a..f703391279 100644
--- a/src/shared/varlink.h
+++ b/src/shared/varlink.h
@@ -213,6 +213,8 @@ typedef enum VarlinkInvocationFlags {
 
 int varlink_invocation(VarlinkInvocationFlags flags);
 
+int varlink_error_to_errno(const char *error, JsonVariant *parameters);
+
 DEFINE_TRIVIAL_CLEANUP_FUNC(Varlink *, varlink_unref);
 DEFINE_TRIVIAL_CLEANUP_FUNC(Varlink *, varlink_close_unref);
 DEFINE_TRIVIAL_CLEANUP_FUNC(Varlink *, varlink_flush_close_unref);
-- 
2.25.1