libnvme: enforce ABI boundary with -fvisibility=hidden

Add -fvisibility=hidden to the libnvme library build and introduce a
LIBNVME_PUBLIC macro (defined as __attribute__((visibility("default")))
in lib-types.h) to explicitly mark each exported function definition.

With this change the compiler enforces the ABI boundary rather than
relying solely on the linker version scripts (libnvme.ld, libnvmf.ld,
accessors.ld).  The immediate benefits are:

 - Any function accidentally omitted from the version script but lacking
   LIBNVME_PUBLIC will be hidden at compile time, making the omission
   visible as a link error rather than a silent symbol leak.
 - nm -D on the installed .so gives an authoritative, minimal symbol
   list suitable for CI checks and abidiff.

The annotation is placed on function *definitions* in the .c files only.
Installed public headers are left unannotated so that third-party code
that includes them is not exposed to a build-internal attribute.

The generate-accessors tool is updated to emit LIBNVME_PUBLIC on the
generated function definitions in accessors.c.

While auditing the version scripts, 34 stale symbol entries that had no
corresponding definition in the source tree were removed from libnvme.ld
and libnvmf.ld.

Signed-off-by: Martin Belanger <[email protected]>

Author: Martin Belanger

libnvme/src/libnvme.ld

@@ -56,7 +56,6 @@ LIBNVME_3 {
 		nvme_get_ns_attr;
 		nvme_get_nsid;
 		nvme_get_path_attr;
-		nvme_get_property;
 		nvme_get_subsys_attr;
 		nvme_get_telemetry_log;
 		nvme_get_telemetry_max;
@@ -89,13 +88,11 @@ LIBNVME_3 {
 		nvme_mi_aem_get_next_event;
 		nvme_mi_aem_process;
 		nvme_mi_close;
-		nvme_mi_close_transport_handle;
 		nvme_mi_control;
 		nvme_mi_ctrl_id;
 		nvme_mi_endpoint_desc;
 		nvme_mi_ep_get_timeout;
 		nvme_mi_ep_set_timeout;
-		nvme_mi_first_ctrl;
 		nvme_mi_first_endpoint;
 		nvme_mi_init_transport_handle;
 		nvme_mi_mi_config_get;
@@ -106,7 +103,6 @@ LIBNVME_3 {
 		nvme_mi_mi_read_mi_data_subsys;
 		nvme_mi_mi_subsystem_health_status_poll;
 		nvme_mi_mi_xfer;
-		nvme_mi_next_ctrl;
 		nvme_mi_next_endpoint;
 		nvme_mi_open_mctp;
 		nvme_mi_scan_ep;
@@ -115,16 +111,13 @@ LIBNVME_3 {
 		nvme_mi_status_to_string;
 		nvme_mi_submit_entry;
 		nvme_mi_submit_exit;
-		nvme_namespace_attach_ctrls;
-		nvme_namespace_detach_ctrls;
 		nvme_filter_namespace;
 		nvme_namespace_first_path;
 		nvme_namespace_next_path;
 		nvme_free_nbft;
 		nvme_read_nbft;
 		nvme_next_host;
 		nvme_next_subsystem;
-		nvme_ns_attach;
 		nvme_ns_compare;
 		nvme_ns_flush;
 		nvme_ns_get_csi;
@@ -153,7 +146,6 @@ LIBNVME_3 {
 		nvme_read_config;
 		nvme_read_key;
 		nvme_refresh_topology;
-		nvme_release_fds;
 		nvme_rescan_ctrl;
 		nvme_revoke_tls_key;
 		nvme_scan_ctrl;
@@ -171,9 +163,6 @@ LIBNVME_3 {
 		nvme_set_ioctl_probing;
 		nvme_set_keyring;
 		nvme_set_logging_level;
-		nvme_set_probe_enabled;
-		nvme_set_property;
-		nvme_set_root;
 		nvme_skip_namespaces;
 		nvme_status_to_errno;
 		nvme_status_to_string;

libnvme/src/libnvmf.ld

@@ -22,32 +22,6 @@ LIBNVMF_3 {
 		nvmf_discovery;
 		nvmf_discovery_config_file;
 		nvmf_discovery_config_json;
-		nvmf_discovery_ctx_already_connected_set;
-		nvmf_discovery_ctx_connected_set;
-		nvmf_discovery_ctx_create;
-		nvmf_discovery_ctx_ctrlkey_set;
-		nvmf_discovery_ctx_decide_retry_set;
-		nvmf_discovery_ctx_default_fabrics_config_set;
-		nvmf_discovery_ctx_device_set;
-		nvmf_discovery_ctx_discovery_log_set;
-		nvmf_discovery_ctx_host_iface_set;
-		nvmf_discovery_ctx_host_traddr_set;
-		nvmf_discovery_ctx_hostid_set;
-		nvmf_discovery_ctx_hostkey_set;
-		nvmf_discovery_ctx_hostnqn_set;
-		nvmf_discovery_ctx_keep_alive_timeout;
-		nvmf_discovery_ctx_keyring_set;
-		nvmf_discovery_ctx_max_retries;
-		nvmf_discovery_ctx_parser_cleanup_set;
-		nvmf_discovery_ctx_parser_init_set;
-		nvmf_discovery_ctx_parser_next_line_set;
-		nvmf_discovery_ctx_persistent_set;
-		nvmf_discovery_ctx_subsysnqn_set;
-		nvmf_discovery_ctx_tls_key_identity_set;
-		nvmf_discovery_ctx_tls_key_set;
-		nvmf_discovery_ctx_traddr_set;
-		nvmf_discovery_ctx_transport_set;
-		nvmf_discovery_ctx_trsvcid_set;
 		nvmf_discovery_nbft;
 		nvmf_eflags_str;
 		nvmf_exat_ptr_next;

libnvme/src/meson.build

@@ -96,6 +96,7 @@ libnvme = library(
     'nvme', # produces libnvme.so
     sources,
     version: libnvme_so_version,
+    c_args: ['-fvisibility=hidden'],
     link_args: link_args,
     dependencies: deps,
     install: true,