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sd-varlink: export sd_varlink_set_sentinel

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I tried to implement a varlink service using sd-varlink, and
not being able to use the approach with sentinel is exteremely
painful. This is useful internally and likewise externally.
This commit is contained in:
Zbigniew Jędrzejewski-Szmek
2026-03-29 20:32:15 +02:00
committed by Daan De Meyer
parent 34c82cbe2f
commit ab3a2f375f
19 changed files with 61 additions and 57 deletions
Download Patch File Download Diff File Expand all files Collapse all files
src/bootctl/bootctl-status.c
+1 -2
View File
@@ -22,7 +22,6 @@
#include "pretty-print.h"
#include "string-util.h"
#include "tpm2-util.h"
#include "varlink-util.h"
static int status_entries(
const BootConfig *config,
@@ -705,7 +704,7 @@ int vl_method_list_boot_entries(sd_varlink *link, sd_json_variant *parameters, s
if (r < 0)
return r;
r = varlink_set_sentinel(link, "io.systemd.BootControl.NoSuchBootEntry");
r = sd_varlink_set_sentinel(link, "io.systemd.BootControl.NoSuchBootEntry");
if (r < 0)
return r;
src/core/varlink-dynamic-user.c
+2 -3
View File
@@ -10,7 +10,6 @@
#include "uid-classification.h"
#include "user-util.h"
#include "varlink-dynamic-user.h"
#include "varlink-util.h"
typedef struct LookupParameters {
const char *user_name;
@@ -78,7 +77,7 @@ int vl_method_get_user_record(sd_varlink *link, sd_json_variant *parameters, sd_
if (!streq_ptr(p.service, "io.systemd.DynamicUser"))
return sd_varlink_error(link, "io.systemd.UserDatabase.BadService", NULL);
r = varlink_set_sentinel(link, "io.systemd.UserDatabase.NoRecordFound");
r = sd_varlink_set_sentinel(link, "io.systemd.UserDatabase.NoRecordFound");
if (r < 0)
return r;
@@ -182,7 +181,7 @@ int vl_method_get_group_record(sd_varlink *link, sd_json_variant *parameters, sd
if (r != 0)
return r;
r = varlink_set_sentinel(link, "io.systemd.UserDatabase.NoRecordFound");
r = sd_varlink_set_sentinel(link, "io.systemd.UserDatabase.NoRecordFound");
if (r < 0)
return r;
src/core/varlink-manager.c
+1 -1
View File
@@ -334,7 +334,7 @@ int vl_method_enqueue_marked_jobs_manager(sd_varlink *link, sd_json_variant *par
if (r <= 0)
return r;
r = varlink_set_sentinel(link, NULL);
r = sd_varlink_set_sentinel(link, NULL);
if (r < 0)
return r;
src/core/varlink-unit.c
+1 -1
View File
@@ -514,7 +514,7 @@ int vl_method_list_units(sd_varlink *link, sd_json_variant *parameters, sd_varli
if (!FLAGS_SET(flags, SD_VARLINK_METHOD_MORE))
return sd_varlink_error(link, SD_VARLINK_ERROR_EXPECTED_MORE, NULL);
r = varlink_set_sentinel(link, VARLINK_ERROR_UNIT_NO_SUCH_UNIT);
r = sd_varlink_set_sentinel(link, VARLINK_ERROR_UNIT_NO_SUCH_UNIT);
if (r < 0)
return r;
src/home/homed-varlink.c
+3 -4
View File
@@ -14,7 +14,6 @@
#include "user-record.h"
#include "user-record-util.h"
#include "user-util.h"
#include "varlink-util.h"
typedef struct LookupParameters {
const char *user_name;
@@ -104,7 +103,7 @@ int vl_method_get_user_record(sd_varlink *link, sd_json_variant *parameters, sd_
if (!streq_ptr(p.service, m->userdb_service))
return sd_varlink_error(link, "io.systemd.UserDatabase.BadService", NULL);
r = varlink_set_sentinel(link, "io.systemd.UserDatabase.NoRecordFound");
r = sd_varlink_set_sentinel(link, "io.systemd.UserDatabase.NoRecordFound");
if (r < 0)
return r;
@@ -212,7 +211,7 @@ int vl_method_get_group_record(sd_varlink *link, sd_json_variant *parameters, sd
if (!streq_ptr(p.service, m->userdb_service))
return sd_varlink_error(link, "io.systemd.UserDatabase.BadService", NULL);
r = varlink_set_sentinel(link, "io.systemd.UserDatabase.NoRecordFound");
r = sd_varlink_set_sentinel(link, "io.systemd.UserDatabase.NoRecordFound");
if (r < 0)
return r;
@@ -277,7 +276,7 @@ int vl_method_get_memberships(sd_varlink *link, sd_json_variant *parameters, sd_
if (!streq_ptr(p.service, m->userdb_service))
return sd_varlink_error(link, "io.systemd.UserDatabase.BadService", NULL);
r = varlink_set_sentinel(link, "io.systemd.UserDatabase.NoRecordFound");
r = sd_varlink_set_sentinel(link, "io.systemd.UserDatabase.NoRecordFound");
if (r < 0)
return r;
src/import/importd.c
+1 -1
View File
@@ -1837,7 +1837,7 @@ static int vl_method_list_transfers(sd_varlink *link, sd_json_variant *parameter
if (r != 0)
return r;
r = varlink_set_sentinel(link, "io.systemd.Import.NoTransfers");
r = sd_varlink_set_sentinel(link, "io.systemd.Import.NoTransfers");
if (r < 0)
return r;
src/journal/journalctl-varlink-server.c
+1 -2
View File
@@ -14,7 +14,6 @@
#include "strv.h"
#include "unit-name.h" /* IWYU pragma: keep */
#include "user-util.h"
#include "varlink-util.h"
typedef struct GetEntriesParameters {
char **units;
@@ -100,7 +99,7 @@ int vl_method_get_entries(sd_varlink *link, sd_json_variant *parameters, sd_varl
if (r < 0)
return r;
r = varlink_set_sentinel(link, "io.systemd.JournalAccess.NoEntries");
r = sd_varlink_set_sentinel(link, "io.systemd.JournalAccess.NoEntries");
if (r < 0)
return r;
src/libsystemd/libsystemd.sym
+5
View File
@@ -1090,3 +1090,8 @@ LIBSYSTEMD_260 {
global:
sd_session_get_extra_device_access;
} LIBSYSTEMD_259;
LIBSYSTEMD_261 {
global:
sd_varlink_set_sentinel;
} LIBSYSTEMD_260;
src/libsystemd/sd-varlink/sd-varlink.c
+25
View File
@@ -2945,6 +2945,31 @@ _public_ void* sd_varlink_get_userdata(sd_varlink *v) {
return v->userdata;
}
_public_ int sd_varlink_set_sentinel(sd_varlink *v, const char *error_id) {
assert_return(v, -EINVAL);
/* If the caller doesn't want a reply, then don't set a sentinel. */
if (v->state == VARLINK_PROCESSING_METHOD_ONEWAY)
return 0;
/* This has to be called during a callback, and not after it has exited. */
assert_return(IN_SET(v->state, VARLINK_PROCESSING_METHOD, VARLINK_PROCESSING_METHOD_MORE),
-EUCLEAN);
char *s = NULL;
if (error_id) {
s = strdup(error_id);
if (!s)
return log_oom_debug();
}
if (v->sentinel != POINTER_MAX)
free(v->sentinel);
v->sentinel = s ?: POINTER_MAX;
return 0;
}
static int varlink_acquire_ucred(sd_varlink *v) {
int r;
src/libsystemd/sd-varlink/varlink-util.c
-25
View File
@@ -205,31 +205,6 @@ int varlink_check_privileged_peer(sd_varlink *vl) {
return 0;
}
int varlink_set_sentinel(sd_varlink *v, const char *error_id) {
_cleanup_free_ char *s = NULL;
assert(v);
/* If the caller doesn't want a reply, then don't set a sentinel. */
if (v->state == VARLINK_PROCESSING_METHOD_ONEWAY)
return 0;
/* This has to be called during a callback, and not after it has exited. */
assert(IN_SET(v->state, VARLINK_PROCESSING_METHOD, VARLINK_PROCESSING_METHOD_MORE));
if (error_id) {
s = strdup(error_id);
if (!s)
return -ENOMEM;
}
if (v->sentinel != POINTER_MAX)
free(v->sentinel);
v->sentinel = s ? TAKE_PTR(s) : POINTER_MAX;
return 0;
}
DEFINE_HASH_OPS_WITH_VALUE_DESTRUCTOR(
varlink_hash_ops,
void,
src/libsystemd/sd-varlink/varlink-util.h
-2
View File
@@ -28,6 +28,4 @@ int varlink_server_new(
int varlink_check_privileged_peer(sd_varlink *vl);
int varlink_set_sentinel(sd_varlink *v, const char *error_id);
extern const struct hash_ops varlink_hash_ops;
src/machine/machined-varlink.c
+2 -2
View File
@@ -534,7 +534,7 @@ static int vl_method_list(sd_varlink *link, sd_json_variant *parameters, sd_varl
if (r != 0)
return r;
r = varlink_set_sentinel(link, VARLINK_ERROR_MACHINE_NO_SUCH_MACHINE);
r = sd_varlink_set_sentinel(link, VARLINK_ERROR_MACHINE_NO_SUCH_MACHINE);
if (r < 0)
return r;
@@ -681,7 +681,7 @@ static int vl_method_list_images(sd_varlink *link, sd_json_variant *parameters,
if (r != 0)
return r;
r = varlink_set_sentinel(link, VARLINK_ERROR_MACHINE_IMAGE_NO_SUCH_IMAGE);
r = sd_varlink_set_sentinel(link, VARLINK_ERROR_MACHINE_IMAGE_NO_SUCH_IMAGE);
if (r < 0)
return r;
src/pcrlock/pcrlock.c
+1 -1
View File
@@ -5420,7 +5420,7 @@ static int vl_method_read_event_log(sd_varlink *link, sd_json_variant *parameter
return r;
// FIXME: We can't use a NULL sentinel here because the output fields in the IDL are non-nullable.
r = varlink_set_sentinel(link, NULL);
r = sd_varlink_set_sentinel(link, NULL);
if (r < 0)
return r;
src/repart/repart.c
+1 -1
View File
@@ -10427,7 +10427,7 @@ static int vl_method_list_candidate_devices(
if (r < 0)
return r;
r = varlink_set_sentinel(link, "io.systemd.Repart.NoCandidateDevices");
r = sd_varlink_set_sentinel(link, "io.systemd.Repart.NoCandidateDevices");
if (r < 0)
return r;
src/shared/metrics.c
+2 -2
View File
@@ -90,7 +90,7 @@ int metrics_method_describe(
if (r != 0)
return r;
r = varlink_set_sentinel(link, "io.systemd.Metrics.NoSuchMetric");
r = sd_varlink_set_sentinel(link, "io.systemd.Metrics.NoSuchMetric");
if (r < 0)
return r;
@@ -127,7 +127,7 @@ int metrics_method_list(
if (r != 0)
return r;
r = varlink_set_sentinel(link, "io.systemd.Metrics.NoSuchMetric");
r = sd_varlink_set_sentinel(link, "io.systemd.Metrics.NoSuchMetric");
if (r < 0)
return r;
src/sysext/sysext.c
+1 -1
View File
@@ -2778,7 +2778,7 @@ static int vl_method_list(sd_varlink *link, sd_json_variant *parameters, sd_varl
if (r < 0)
return r;
r = varlink_set_sentinel(link, "io.systemd.sysext.NoImagesFound");
r = sd_varlink_set_sentinel(link, "io.systemd.sysext.NoImagesFound");
if (r < 0)
return r;
src/systemd/sd-varlink.h
+5
View File
@@ -205,6 +205,11 @@ int sd_varlink_bind_reply(sd_varlink *v, sd_varlink_reply_t reply);
void* sd_varlink_set_userdata(sd_varlink *v, void *userdata);
void* sd_varlink_get_userdata(sd_varlink *v);
/* Queue a reply to be sent if no other reply was sent by a method callback.
* Useful when implementing services which send a (possibly empty) series
* of objects and terminate. */
int sd_varlink_set_sentinel(sd_varlink *v, const char *error_id);
int sd_varlink_get_peer_uid(sd_varlink *v, uid_t *ret);
int sd_varlink_get_peer_gid(sd_varlink *v, gid_t *ret);
int sd_varlink_get_peer_pid(sd_varlink *v, pid_t *ret);
src/test/test-varlink.c
+6 -6
View File
@@ -443,7 +443,7 @@ TEST(invalid_parameter) {
static int method_with_error_sentinel(sd_varlink *link, sd_json_variant *parameters, sd_varlink_method_flags_t flags, void *userdata) {
/* Set an error sentinel and return without sending a reply. The sentinel error should be sent automatically. */
ASSERT_OK(varlink_set_sentinel(link, "io.test.SentinelError"));
ASSERT_OK(sd_varlink_set_sentinel(link, "io.test.SentinelError"));
return 0;
}
@@ -482,7 +482,7 @@ TEST(sentinel_error) {
static int method_with_empty_sentinel(sd_varlink *link, sd_json_variant *parameters, sd_varlink_method_flags_t flags, void *userdata) {
/* Set an empty sentinel and return without sending a reply. An empty reply should be sent automatically. */
ASSERT_OK(varlink_set_sentinel(link, /* error_id= */ NULL));
ASSERT_OK(sd_varlink_set_sentinel(link, /* error_id= */ NULL));
return 0;
}
@@ -522,7 +522,7 @@ TEST(sentinel_empty) {
static int method_with_sentinel_but_reply(sd_varlink *link, sd_json_variant *parameters, sd_varlink_method_flags_t flags, void *userdata) {
/* Set a sentinel but also send a reply. The sentinel should not be used. */
ASSERT_OK(varlink_set_sentinel(link, "io.test.SentinelError"));
ASSERT_OK(sd_varlink_set_sentinel(link, "io.test.SentinelError"));
return sd_varlink_replybo(link, SD_JSON_BUILD_PAIR_STRING("result", "explicit-reply"));
}
@@ -561,10 +561,10 @@ TEST(sentinel_with_explicit_reply) {
}
static int method_with_oneway_sentinel(sd_varlink *link, sd_json_variant *parameters, sd_varlink_method_flags_t flags, void *userdata) {
/* The method was called oneway, so varlink_set_sentinel() should be a no-op and the server should
/* The method was called oneway, so sd_varlink_set_sentinel() should be a no-op and the server should
* transition back to idle without sending any reply. */
ASSERT_TRUE(FLAGS_SET(flags, SD_VARLINK_METHOD_ONEWAY));
ASSERT_OK(varlink_set_sentinel(link, "io.test.SentinelError"));
ASSERT_OK(sd_varlink_set_sentinel(link, "io.test.SentinelError"));
return 0;
}
@@ -619,7 +619,7 @@ static int method_with_fd_sentinel(sd_varlink *link, sd_json_variant *parameters
/* Set a sentinel so sd_varlink_reply() defers sending: each reply and its pushed fds are captured in
* the queue, and the last one is sent as the final reply when the callback returns. */
ASSERT_OK(varlink_set_sentinel(link, /* error_id= */ NULL));
ASSERT_OK(sd_varlink_set_sentinel(link, /* error_id= */ NULL));
/* First reply: push one fd with "alpha" content */
ASSERT_OK(fd1 = memfd_new_and_seal_string("data", "alpha"));
src/userdb/userwork.c
+3 -3
View File
@@ -172,7 +172,7 @@ static int vl_method_get_user_record(sd_varlink *link, sd_json_variant *paramete
* we are done'; == 0 means 'not processed, caller should process now' */
return r;
r = varlink_set_sentinel(link, "io.systemd.UserDatabase.NoRecordFound");
r = sd_varlink_set_sentinel(link, "io.systemd.UserDatabase.NoRecordFound");
if (r < 0)
return r;
@@ -313,7 +313,7 @@ static int vl_method_get_group_record(sd_varlink *link, sd_json_variant *paramet
if (r != 0)
return r;
r = varlink_set_sentinel(link, "io.systemd.UserDatabase.NoRecordFound");
r = sd_varlink_set_sentinel(link, "io.systemd.UserDatabase.NoRecordFound");
if (r < 0)
return r;
@@ -401,7 +401,7 @@ static int vl_method_get_memberships(sd_varlink *link, sd_json_variant *paramete
if (r != 0)
return r;
r = varlink_set_sentinel(link, "io.systemd.UserDatabase.NoRecordFound");
r = sd_varlink_set_sentinel(link, "io.systemd.UserDatabase.NoRecordFound");
if (r < 0)
return r;