blob: 905bd270d9916aaf32ecb733008a9623436d4ede [file] [log] [blame]
"""This is an experimental implementation of cc_shared_library.
We may change the implementation at any moment or even delete this file. Do not
rely on this. It requires bazel >1.2 and passing the flag
--experimental_cc_shared_library
"""
load("@bazel_skylib//rules:common_settings.bzl", "BuildSettingInfo")
load("//cc:find_cc_toolchain.bzl", "find_cc_toolchain")
# TODO(#5200): Add export_define to library_to_link and cc_library
# Add this as a tag to any target that can be linked by more than one
# cc_shared_library because it doesn't have static initializers or anything
# else that may cause issues when being linked more than once. This should be
# used sparingly after making sure it's safe to use.
LINKABLE_MORE_THAN_ONCE = "LINKABLE_MORE_THAN_ONCE"
CcSharedLibraryPermissionsInfo = provider(
"Permissions for a cc shared library.",
fields = {
"targets": "Matches targets that can be exported.",
},
)
GraphNodeInfo = provider(
"Nodes in the graph of shared libraries.",
fields = {
"children": "Other GraphNodeInfo from dependencies of this target",
"label": "Label of the target visited",
"linkable_more_than_once": "Linkable into more than a single cc_shared_library",
},
)
CcSharedLibraryInfo = provider(
"Information about a cc shared library.",
fields = {
"dynamic_deps": "All shared libraries depended on transitively",
"exports": "cc_libraries that are linked statically and exported",
"link_once_static_libs": "All libraries linked statically into this library that should " +
"only be linked once, e.g. because they have static " +
"initializers. If we try to link them more than once, " +
"we will throw an error",
"linker_input": "the resulting linker input artifact for the shared library",
"preloaded_deps": "cc_libraries needed by this cc_shared_library that should" +
" be linked the binary. If this is set, this cc_shared_library has to " +
" be a direct dependency of the cc_binary",
},
)
def _separate_static_and_dynamic_link_libraries(
direct_children,
can_be_linked_dynamically,
preloaded_deps_direct_labels):
node = None
all_children = list(direct_children)
link_statically_labels = {}
link_dynamically_labels = {}
seen_labels = {}
# Horrible I know. Perhaps Starlark team gives me a way to prune a tree.
for i in range(2147483647):
if i == len(all_children):
break
node = all_children[i]
node_label = str(node.label)
if node_label in seen_labels:
continue
seen_labels[node_label] = True
if node_label in can_be_linked_dynamically:
link_dynamically_labels[node_label] = True
elif node_label not in preloaded_deps_direct_labels:
link_statically_labels[node_label] = node.linkable_more_than_once
all_children.extend(node.children)
return (link_statically_labels, link_dynamically_labels)
def _create_linker_context(ctx, linker_inputs):
return cc_common.create_linking_context(
linker_inputs = depset(linker_inputs, order = "topological"),
)
def _merge_cc_shared_library_infos(ctx):
dynamic_deps = []
transitive_dynamic_deps = []
for dep in ctx.attr.dynamic_deps:
if dep[CcSharedLibraryInfo].preloaded_deps != None:
fail("{} can only be a direct dependency of a " +
" cc_binary because it has " +
"preloaded_deps".format(str(dep.label)))
dynamic_dep_entry = (
dep[CcSharedLibraryInfo].exports,
dep[CcSharedLibraryInfo].linker_input,
dep[CcSharedLibraryInfo].link_once_static_libs,
)
dynamic_deps.append(dynamic_dep_entry)
transitive_dynamic_deps.append(dep[CcSharedLibraryInfo].dynamic_deps)
return depset(direct = dynamic_deps, transitive = transitive_dynamic_deps)
def _build_exports_map_from_only_dynamic_deps(merged_shared_library_infos):
exports_map = {}
for entry in merged_shared_library_infos.to_list():
exports = entry[0]
linker_input = entry[1]
for export in exports:
if export in exports_map:
fail("Two shared libraries in dependencies export the same symbols. Both " +
exports_map[export].libraries[0].dynamic_library.short_path +
" and " + linker_input.libraries[0].dynamic_library.short_path +
" export " + export)
exports_map[export] = linker_input
return exports_map
def _build_link_once_static_libs_map(merged_shared_library_infos):
link_once_static_libs_map = {}
for entry in merged_shared_library_infos.to_list():
link_once_static_libs = entry[2]
linker_input = entry[1]
for static_lib in link_once_static_libs:
if static_lib in link_once_static_libs_map:
fail("Two shared libraries in dependencies link the same " +
" library statically. Both " + link_once_static_libs_map[static_lib] +
" and " + str(linker_input.owner) +
" link statically" + static_lib)
link_once_static_libs_map[static_lib] = str(linker_input.owner)
return link_once_static_libs_map
def _wrap_static_library_with_alwayslink(ctx, feature_configuration, cc_toolchain, linker_input):
new_libraries_to_link = []
for old_library_to_link in linker_input.libraries:
# TODO(#5200): This will lose the object files from a library to link.
# Not too bad for the prototype but as soon as the library_to_link
# constructor has object parameters this should be changed.
new_library_to_link = cc_common.create_library_to_link(
actions = ctx.actions,
feature_configuration = feature_configuration,
cc_toolchain = cc_toolchain,
static_library = old_library_to_link.static_library,
pic_static_library = old_library_to_link.pic_static_library,
alwayslink = True,
)
new_libraries_to_link.append(new_library_to_link)
return cc_common.create_linker_input(
owner = linker_input.owner,
libraries = depset(direct = new_libraries_to_link),
user_link_flags = depset(direct = linker_input.user_link_flags),
additional_inputs = depset(direct = linker_input.additional_inputs),
)
def _check_if_target_under_path(value, pattern):
if pattern.workspace_name != value.workspace_name:
return False
if pattern.name == "__pkg__":
return pattern.package == value.package
if pattern.name == "__subpackages__":
return _same_package_or_above(pattern, value)
return pattern.package == value.package and pattern.name == value.name
def _check_if_target_can_be_exported(target, current_label, permissions):
if permissions == None:
return True
if (target.workspace_name != current_label.workspace_name or
_same_package_or_above(current_label, target)):
return True
matched_by_target = False
for permission in permissions:
for permission_target in permission[CcSharedLibraryPermissionsInfo].targets:
if _check_if_target_under_path(target, permission_target):
return True
return False
def _check_if_target_should_be_exported_without_filter(target, current_label, permissions):
return _check_if_target_should_be_exported_with_filter(target, current_label, None, permissions)
def _check_if_target_should_be_exported_with_filter(target, current_label, exports_filter, permissions):
should_be_exported = False
if exports_filter == None:
should_be_exported = True
else:
for export_filter in exports_filter:
export_filter_label = current_label.relative(export_filter)
if _check_if_target_under_path(target, export_filter_label):
should_be_exported = True
break
if should_be_exported:
if _check_if_target_can_be_exported(target, current_label, permissions):
return True
else:
matched_by_filter_text = ""
if exports_filter:
matched_by_filter_text = " (matched by filter) "
fail(str(target) + matched_by_filter_text +
" cannot be exported from " + str(current_label) +
" because it's not in the same package/subpackage and the library " +
"doesn't have the necessary permissions. Use cc_shared_library_permissions.")
return False
def _filter_inputs(
ctx,
feature_configuration,
cc_toolchain,
transitive_exports,
preloaded_deps_direct_labels,
link_once_static_libs_map):
linker_inputs = []
link_once_static_libs = []
graph_structure_aspect_nodes = []
dependency_linker_inputs = []
direct_exports = {}
for export in ctx.attr.roots:
direct_exports[str(export.label)] = True
dependency_linker_inputs.extend(export[CcInfo].linking_context.linker_inputs.to_list())
graph_structure_aspect_nodes.append(export[GraphNodeInfo])
can_be_linked_dynamically = {}
for linker_input in dependency_linker_inputs:
owner = str(linker_input.owner)
if owner in transitive_exports:
can_be_linked_dynamically[owner] = True
(link_statically_labels, link_dynamically_labels) = _separate_static_and_dynamic_link_libraries(
graph_structure_aspect_nodes,
can_be_linked_dynamically,
preloaded_deps_direct_labels,
)
exports = {}
owners_seen = {}
for linker_input in dependency_linker_inputs:
owner = str(linker_input.owner)
if owner in owners_seen:
continue
owners_seen[owner] = True
if owner in link_dynamically_labels:
dynamic_linker_input = transitive_exports[owner]
linker_inputs.append(dynamic_linker_input)
elif owner in link_statically_labels:
if owner in link_once_static_libs_map:
fail(owner + " is already linked statically in " +
link_once_static_libs_map[owner] + " but not exported")
if owner in direct_exports:
wrapped_library = _wrap_static_library_with_alwayslink(
ctx,
feature_configuration,
cc_toolchain,
linker_input,
)
if not link_statically_labels[owner]:
link_once_static_libs.append(owner)
linker_inputs.append(wrapped_library)
else:
can_be_linked_statically = False
for static_dep_path in ctx.attr.static_deps:
static_dep_path_label = ctx.label.relative(static_dep_path)
if _check_if_target_under_path(linker_input.owner, static_dep_path_label):
can_be_linked_statically = True
break
if _check_if_target_should_be_exported_with_filter(
linker_input.owner,
ctx.label,
ctx.attr.exports_filter,
_get_permissions(ctx),
):
exports[owner] = True
can_be_linked_statically = True
if can_be_linked_statically:
if not link_statically_labels[owner]:
link_once_static_libs.append(owner)
linker_inputs.append(linker_input)
else:
fail("We can't link " +
str(owner) + " either statically or dynamically")
return (exports, linker_inputs, link_once_static_libs)
def _same_package_or_above(label_a, label_b):
if label_a.workspace_name != label_b.workspace_name:
return False
package_a_tokenized = label_a.package.split("/")
package_b_tokenized = label_b.package.split("/")
if len(package_b_tokenized) < len(package_a_tokenized):
return False
if package_a_tokenized[0] != "":
for i in range(len(package_a_tokenized)):
if package_a_tokenized[i] != package_b_tokenized[i]:
return False
return True
def _get_permissions(ctx):
if ctx.attr._enable_permissions_check[BuildSettingInfo].value:
return ctx.attr.permissions
return None
def _cc_shared_library_impl(ctx):
cc_common.check_experimental_cc_shared_library()
cc_toolchain = find_cc_toolchain(ctx)
feature_configuration = cc_common.configure_features(
ctx = ctx,
cc_toolchain = cc_toolchain,
requested_features = ctx.features,
unsupported_features = ctx.disabled_features,
)
merged_cc_shared_library_info = _merge_cc_shared_library_infos(ctx)
exports_map = _build_exports_map_from_only_dynamic_deps(merged_cc_shared_library_info)
for export in ctx.attr.roots:
if str(export.label) in exports_map:
fail("Trying to export a library already exported by a different shared library: " +
str(export.label))
_check_if_target_should_be_exported_without_filter(export.label, ctx.label, _get_permissions(ctx))
preloaded_deps_direct_labels = {}
preloaded_dep_merged_cc_info = None
if len(ctx.attr.preloaded_deps) != 0:
preloaded_deps_cc_infos = []
for preloaded_dep in ctx.attr.preloaded_deps:
preloaded_deps_direct_labels[str(preloaded_dep.label)] = True
preloaded_deps_cc_infos.append(preloaded_dep[CcInfo])
preloaded_dep_merged_cc_info = cc_common.merge_cc_infos(cc_infos = preloaded_deps_cc_infos)
link_once_static_libs_map = _build_link_once_static_libs_map(merged_cc_shared_library_info)
(exports, linker_inputs, link_once_static_libs) = _filter_inputs(
ctx,
feature_configuration,
cc_toolchain,
exports_map,
preloaded_deps_direct_labels,
link_once_static_libs_map,
)
linking_context = _create_linker_context(ctx, linker_inputs)
user_link_flags = []
for user_link_flag in ctx.attr.user_link_flags:
user_link_flags.append(ctx.expand_location(user_link_flag, targets = ctx.attr.additional_linker_inputs))
linking_outputs = cc_common.link(
actions = ctx.actions,
feature_configuration = feature_configuration,
cc_toolchain = cc_toolchain,
linking_contexts = [linking_context],
user_link_flags = user_link_flags,
additional_inputs = ctx.files.additional_linker_inputs,
name = ctx.label.name,
output_type = "dynamic_library",
)
runfiles = ctx.runfiles(
files = [linking_outputs.library_to_link.resolved_symlink_dynamic_library],
)
for dep in ctx.attr.dynamic_deps:
runfiles = runfiles.merge(dep[DefaultInfo].data_runfiles)
for export in ctx.attr.roots:
exports[str(export.label)] = True
debug_files = []
if ctx.attr._experimental_debug[BuildSettingInfo].value:
exports_debug_file = ctx.actions.declare_file(ctx.label.name + "_exports.txt")
ctx.actions.write(content = "\n".join(exports.keys()), output = exports_debug_file)
link_once_static_libs_debug_file = ctx.actions.declare_file(ctx.label.name + "_link_once_static_libs.txt")
ctx.actions.write(content = "\n".join(link_once_static_libs), output = link_once_static_libs_debug_file)
debug_files.append(exports_debug_file)
debug_files.append(link_once_static_libs_debug_file)
if not ctx.attr._incompatible_link_once[BuildSettingInfo].value:
link_once_static_libs = []
return [
DefaultInfo(
files = depset([linking_outputs.library_to_link.resolved_symlink_dynamic_library] + debug_files),
runfiles = runfiles,
),
CcSharedLibraryInfo(
dynamic_deps = merged_cc_shared_library_info,
exports = exports.keys(),
link_once_static_libs = link_once_static_libs,
linker_input = cc_common.create_linker_input(
owner = ctx.label,
libraries = depset([linking_outputs.library_to_link]),
),
preloaded_deps = preloaded_dep_merged_cc_info,
),
]
def _graph_structure_aspect_impl(target, ctx):
children = []
if hasattr(ctx.rule.attr, "deps"):
for dep in ctx.rule.attr.deps:
if GraphNodeInfo in dep:
children.append(dep[GraphNodeInfo])
# TODO(bazel-team): Add flag to Bazel that can toggle the initialization of
# linkable_more_than_once.
linkable_more_than_once = False
if hasattr(ctx.rule.attr, "tags"):
for tag in ctx.rule.attr.tags:
if tag == LINKABLE_MORE_THAN_ONCE:
linkable_more_than_once = True
return [GraphNodeInfo(
label = ctx.label,
children = children,
linkable_more_than_once = linkable_more_than_once,
)]
def _cc_shared_library_permissions_impl(ctx):
targets = []
for target_filter in ctx.attr.targets:
target_filter_label = ctx.label.relative(target_filter)
if not _check_if_target_under_path(target_filter_label, ctx.label.relative(":__subpackages__")):
fail("A cc_shared_library_permissions rule can only list " +
"targets that are in the same package or a sub-package")
targets.append(target_filter_label)
return [CcSharedLibraryPermissionsInfo(
targets = targets,
)]
graph_structure_aspect = aspect(
attr_aspects = ["*"],
implementation = _graph_structure_aspect_impl,
)
cc_shared_library_permissions = rule(
implementation = _cc_shared_library_permissions_impl,
attrs = {
"targets": attr.string_list(),
},
)
cc_shared_library = rule(
implementation = _cc_shared_library_impl,
attrs = {
"additional_linker_inputs": attr.label_list(allow_files = True),
"dynamic_deps": attr.label_list(providers = [CcSharedLibraryInfo]),
"exports_filter": attr.string_list(),
"permissions": attr.label_list(providers = [CcSharedLibraryPermissionsInfo]),
"preloaded_deps": attr.label_list(providers = [CcInfo]),
"roots": attr.label_list(providers = [CcInfo], aspects = [graph_structure_aspect]),
"static_deps": attr.string_list(),
"user_link_flags": attr.string_list(),
"_cc_toolchain": attr.label(default = "@bazel_tools//tools/cpp:current_cc_toolchain"),
"_enable_permissions_check": attr.label(default = "//examples:enable_permissions_check"),
"_experimental_debug": attr.label(default = "//examples:experimental_debug"),
"_incompatible_link_once": attr.label(default = "//examples:incompatible_link_once"),
},
toolchains = ["@bazel_tools//tools/cpp:toolchain_type"], # copybara-use-repo-external-label
fragments = ["cpp"],
incompatible_use_toolchain_transition = True,
)
for_testing_dont_use_check_if_target_under_path = _check_if_target_under_path