// file : libbuild2/rule.cxx -*- C++ -*- // license : MIT; see accompanying LICENSE file #include #include #include #include #include #include #include using namespace std; using namespace butl; namespace build2 { // rule (vtable) // rule:: ~rule () { } // file_rule // // Note that this rule is special. It is the last, fallback rule. If // it doesn't match, then no other rule can possibly match and we have // an error. It also cannot be ambigious with any other rule. As a // result the below implementation bends or ignores quite a few rules // that normal implementations should follow. So you probably shouldn't // use it as a guide to implement your own, normal, rules. // bool file_rule:: match (action a, target& t, const string&) const { tracer trace ("file_rule::match"); // While strictly speaking we should check for the file's existence // for every action (because that's the condition for us matching), // for some actions this is clearly a waste. Say, perform_clean: we // are not doing anything for this action so not checking if the file // exists seems harmless. // switch (a) { case perform_clean_id: return true; default: { // While normally we shouldn't do any of this in match(), no other // rule should ever be ambiguous with the fallback one and path/mtime // access is atomic. In other words, we know what we are doing but // don't do this in normal rules. // First check the timestamp. This takes care of the special "trust // me, this file exists" situations (used, for example, for installed // stuff where we know it's there, just not exactly where). // mtime_target& mt (t.as ()); timestamp ts (mt.mtime ()); if (ts != timestamp_unknown) return ts != timestamp_nonexistent; // Otherwise, if this is not a path_target, then we don't match. // path_target* pt (mt.is_a ()); if (pt == nullptr) return false; const path* p (&pt->path ()); // Assign the path. // if (p->empty ()) { // Since we cannot come up with an extension, ask the target's // derivation function to treat this as a prerequisite (just like in // search_existing_file()). // if (pt->derive_extension (true) == nullptr) { l4 ([&]{trace << "no default extension for target " << *pt;}); return false; } p = &pt->derive_path (); } ts = mtime (*p); pt->mtime (ts); if (ts != timestamp_nonexistent) return true; l4 ([&]{trace << "no existing file for target " << *pt;}); return false; } } } recipe file_rule:: apply (action a, target& t) const { // Update triggers the update of this target's prerequisites so it would // seem natural that we should also trigger their cleanup. However, this // possibility is rather theoretical so until we see a real use-case for // this functionality, we simply ignore the clean operation. // if (a.operation () == clean_id) return noop_recipe; // If we have no prerequisites, then this means this file is up to date. // Return noop_recipe which will also cause the target's state to be set // to unchanged. This is an important optimization on which quite a few // places that deal with predominantly static content rely. // if (!t.has_group_prerequisites ()) // Group as in match_prerequisites(). return noop_recipe; // Match all the prerequisites. // match_prerequisites (a, t); // Note that we used to provide perform_update() which checked that this // target is not older than any of its prerequisites. However, later we // realized this is probably wrong: consider a script with a testscript as // a prerequisite; chances are the testscript will be newer than the // script and there is nothing wrong with that. // return default_recipe; } const file_rule file_rule::instance; // alias_rule // bool alias_rule:: match (action, target&, const string&) const { return true; } recipe alias_rule:: apply (action a, target& t) const { // Inject dependency on our directory (note: not parent) so that it is // automatically created on update and removed on clean. // inject_fsdir (a, t, false); match_prerequisites (a, t); return default_recipe; } const alias_rule alias_rule::instance; // fsdir_rule // bool fsdir_rule:: match (action, target&, const string&) const { return true; } recipe fsdir_rule:: apply (action a, target& t) const { // Inject dependency on the parent directory. Note that it must be first // (see perform_update_direct()). // inject_fsdir (a, t); match_prerequisites (a, t); switch (a) { case perform_update_id: return &perform_update; case perform_clean_id: return &perform_clean; default: assert (false); return default_recipe; } } static bool fsdir_mkdir (const target& t, const dir_path& d) { // Even with the exists() check below this can still be racy so only print // things if we actually did create it (similar to build2::mkdir()). // auto print = [&t, &d] () { if (verb >= 2) text << "mkdir " << d; else if (verb && t.ctx.current_diag_noise) text << "mkdir " << t; }; // Note: ignoring the dry_run flag. // mkdir_status ms; try { ms = try_mkdir (d); } catch (const system_error& e) { print (); fail << "unable to create directory " << d << ": " << e << endf; } if (ms == mkdir_status::success) { print (); return true; } return false; } target_state fsdir_rule:: perform_update (action a, const target& t) { target_state ts (target_state::unchanged); // First update prerequisites (e.g. create parent directories) then create // this directory. // // @@ outer: should we assume for simplicity its only prereqs are fsdir{}? // if (!t.prerequisite_targets[a].empty ()) ts = straight_execute_prerequisites (a, t); // The same code as in perform_update_direct() below. // const dir_path& d (t.dir); // Everything is in t.dir. // Generally, it is probably correct to assume that in the majority of // cases the directory will already exist. If so, then we are going to get // better performance by first checking if it indeed exists. See // butl::try_mkdir() for details. // // @@ Also skip prerequisites? Can't we return noop in apply? // if (!exists (d) && fsdir_mkdir (t, d)) ts |= target_state::changed; return ts; } void fsdir_rule:: perform_update_direct (action a, const target& t) { // First create the parent directory. If present, it is always first. // const target* p (t.prerequisite_targets[a].empty () ? nullptr : t.prerequisite_targets[a][0]); if (p != nullptr && p->is_a ()) perform_update_direct (a, *p); // The same code as in perform_update() above. // const dir_path& d (t.dir); if (!exists (d)) fsdir_mkdir (t, d); } target_state fsdir_rule:: perform_clean (action a, const target& t) { // The reverse order of update: first delete this directory, then clean // prerequisites (e.g., delete parent directories). // // Don't fail if we couldn't remove the directory because it is not empty // (or is current working directory). In this case rmdir() will issue a // warning when appropriate. // target_state ts (rmdir (t.dir, t, t.ctx.current_diag_noise ? 1 : 2) ? target_state::changed : target_state::unchanged); if (!t.prerequisite_targets[a].empty ()) ts |= reverse_execute_prerequisites (a, t); return ts; } const fsdir_rule fsdir_rule::instance; // noop_rule // bool noop_rule:: match (action, target&, const string&) const { return true; } recipe noop_rule:: apply (action, target&) const { return noop_recipe; } const noop_rule noop_rule::instance; // adhoc_rule // const dir_path adhoc_rule::recipes_build_dir ("recipes"); bool adhoc_rule:: match (action a, target& t, const string& h, optional fallback) const { return !fallback && match (a, t, h); } bool adhoc_rule:: match (action, target&, const string&) const { return true; } void adhoc_rule:: dump_attributes (ostream&) const { } // Scope operation callback that cleans up recipe builds. // target_state adhoc_rule:: clean_recipes_build (action, const scope& rs, const dir&) { context& ctx (rs.ctx); const dir_path& out_root (rs.out_path ()); dir_path d (out_root / rs.root_extra->build_build_dir / recipes_build_dir); if (exists (d)) { if (rmdir_r (ctx, d)) { // Clean up build/build/ if it also became empty. // d = out_root / rs.root_extra->build_build_dir; if (empty (d)) { rmdir (ctx, d, 2); // Clean up build/ if it also became empty (e.g., in case of a build // with a transient configuration). // d = out_root / rs.root_extra->build_dir; if (empty (d)) rmdir (ctx, d, 2); } return target_state::changed; } } return target_state::unchanged; } }