aboutsummaryrefslogtreecommitdiff
path: root/libbuild2/config/init.cxx
blob: 56aed1576fc87ba7b00fcc0530910644c184e374 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
// file      : libbuild2/config/init.cxx -*- C++ -*-
// copyright : Copyright (c) 2014-2019 Code Synthesis Ltd
// license   : MIT; see accompanying LICENSE file

#include <libbuild2/config/init.hxx>

#include <sstream>

#include <libbuild2/file.hxx>
#include <libbuild2/rule.hxx>
#include <libbuild2/lexer.hxx>
#include <libbuild2/scope.hxx>
#include <libbuild2/context.hxx>
#include <libbuild2/function.hxx>
#include <libbuild2/filesystem.hxx>  // exists()
#include <libbuild2/diagnostics.hxx>

#include <libbuild2/config/module.hxx>
#include <libbuild2/config/utility.hxx>
#include <libbuild2/config/operation.hxx>

using namespace std;
using namespace butl;

namespace build2
{
  namespace config
  {
    void
    functions (function_map&); // functions.cxx

    bool
    boot (scope& rs, const location&, unique_ptr<module_base>& mod)
    {
      tracer trace ("config::boot");

      context& ctx (rs.ctx);

      l5 ([&]{trace << "for " << rs;});

      // Note that the config.<name>* variables belong to the module <name>.
      // So the only "special" variables we can allocate in config.* are
      // config.config.*, names that have been "gifted" to us by other modules
      // (like config.version below) as well as names that we have reserved to
      // not be valid module names (`build`). We also currently treat `import`
      // as special.
      //
      auto& vp (rs.ctx.var_pool.rw (rs));

      // While config.config.load (see below) could theoretically be specified
      // in a buildfile, config.config.save is expected to always be specified
      // as a command line override.
      //
      // Note: must be entered during bootstrap since we need it in
      // configure_execute().
      //
      vp.insert<path> ("config.config.save", true /* ovr */);

      // Configuration variables persistence mode.
      //
      // By default a config.* variable is saved in the config.build file if
      // (1) it is explicitly marked as persistent with save_variable() and
      // (2) it is not inherited from an amalgamation that also saves this
      // variable (however, there are some exception; see save_config() for
      // details). If the first condition is not met, then the variable is
      // presumed to be no longer used.
      //
      // The config.config.persist can be used to adjust this default logic.
      // It contains a list of key-value pairs with the key being a variable
      // name pattern and the value specifying the condition/action:
      //
      // <pair>      = <pattern>@<condition>=<action>
      // <condition> = unused|inherited|inherited-used|inherited-unused
      // <action>    = (save|drop)[+warn]
      //
      // The last pattern and condition that matches is used (we may want to
      // change this to more specific pattern later).
      //
      // Note that support for inherited conditions is still a @@ TODO.
      //
      // The create meta-operation by default (i.e., unless a custom value is
      // specified) saves unused config.import.* variables without a warning
      // (since there is no way to "use" such variables in a configuration).
      //
      // Note that variable patterns must be quoted, for example:
      //
      // b "config.config.persist='config.*'@unused=save+warn"
      //
      // Use the NULL value to clear.
      //
      auto& c_p (vp.insert<vector<pair<string, string>>> (
                   "config.config.persist",
                   true /* ovr */,
                   variable_visibility::project));

      // Only create the module if we are configuring or creating or if it was
      // requested with config.config.module (useful if we need to call
      // $config.save() during other meta-operations).
      //
      // Detecting the former (configuring/creating) is a bit tricky since the
      // build2 core may not yet know if this is the case. But we know.
      //
      auto& c_m (vp.insert<bool> ("config.config.module", false /*ovr*/));

      const string& mname (ctx.current_mname);
      const string& oname (ctx.current_oname);

      if ((                   mname == "configure" || mname == "create")  ||
          (mname.empty () && (oname == "configure" || oname == "create")) ||
          cast_false<bool> (rs.vars[c_m]))
      {
        // Used as a variable prefix by configure_execute().
        //
        vp.insert ("config.import");

        unique_ptr<module> m (new module);

        // Adjust priority for the config module and import pseudo-module so
        // that their variables come first in config.build.
        //
        m->save_module ("config", INT32_MIN);
        m->save_module ("import", INT32_MIN);

        m->save_variable (c_p, omit_null);

        mod = move (m);
      }

      // Register the config function family if this is the first instance of
      // the config module.
      //
      if (!function_family::defined (ctx.functions, "config"))
        functions (ctx.functions);

      // Register meta-operations. Note that we don't register create_id
      // since it will be pre-processed into configure.
      //
      rs.insert_meta_operation (configure_id, mo_configure);
      rs.insert_meta_operation (disfigure_id, mo_disfigure);

      return true; // Initialize first (load config.build).
    }

#ifndef BUILD2_BOOTSTRAP
    extern const char host_config[]; // host-config.cxx.in
#endif

    bool
    init (scope& rs,
          scope&,
          const location& l,
          unique_ptr<module_base>& mod,
          bool first,
          bool,
          const variable_map& config_hints)
    {
      tracer trace ("config::init");

      if (!first)
      {
        warn (l) << "multiple config module initializations";
        return true;
      }

      l5 ([&]{trace << "for " << rs;});

      assert (config_hints.empty ()); // We don't known any hints.

      auto& vp (rs.ctx.var_pool.rw (rs));
      auto& c_l (vp.insert<paths> ("config.config.load", true /* ovr */));
      auto& c_v (vp.insert<uint64_t> ("config.version", false /*ovr*/));

      // Load config.build if one exists followed by extra files specified in
      // config.config.load (we don't need to worry about disfigure since we
      // will never be init'ed).
      //
      auto load_config = [&rs, &c_v] (istream& is,
                                      const path_name& in,
                                      const location& l)
      {
        // Check the config version. We assume that old versions cannot
        // understand new configs and new versions are incompatible with old
        // configs.
        //
        // We extract the value manually instead of loading and then checking
        // in order to be able to fixup/migrate the file which we may want to
        // do in the future.
        //

        // This is tricky for stdin since we cannot reopen it (or put more
        // than one character back). So what we are going to do is continue
        // reading after extracting the variable. One side effect of this is
        // that we won't have the config.version variable entered in the scope
        // but that is harmless (we could do it manually if necessary though
        // it's not clear which it should be if we load multiple files).
        //
        lexer lex (is, in);

        // Assume missing version is 0.
        //
        auto p (extract_variable (rs.ctx, lex, c_v));
        uint64_t v (p.second ? cast<uint64_t> (p.first) : 0);

        if (v != module::version)
          fail (l) << "incompatible config file " << in <<
            info << "config file version   " << v
                   << (p.second ? "" : " (missing)") <<
            info << "config module version " << module::version <<
            info << "consider reconfiguring " << project (rs) << '@'
                   << rs.out_path ();

        source (rs, rs, lex);
      };

      auto load_config_file = [&load_config] (const path& f, const location& l)
      {
        path_name fn (f);
        ifdstream ifs;
        load_config (open_file_or_stdin (fn, ifs), fn, l);
      };

      {
        path f (config_file (rs));

        if (exists (f))
          load_config_file (f, l);
      }

      if (lookup l = rs[c_l])
      {
        // Only load files that were specified on our root scope as well as
        // global overrides. This way we can use our override "positioning"
        // machinery (i.e., where the override applies) to decide where the
        // extra config is loaded. The resulting semantics feels quite natural
        // and consistent with command line variable overrides:
        //
        // b   config.config.load=.../config.build  # outermost amalgamation
        // b ./config.config.load=.../config.build  # this project
        // b  !config.config.load=.../config.build  # every project
        //
        if (l.belongs (rs) || l.belongs (rs.ctx.global_scope))
        {
          for (const path& f: cast<paths> (l))
          {
            location l (f);

            const string& s (f.string ());

            if (s[0] != '~')
              load_config_file (f, l);
            else if (s == "~host")
            {
#ifdef BUILD2_BOOTSTRAP
              assert (false);
#else
              istringstream is (host_config);
              load_config (is, path_name (s), l);
#endif
            }
            else
              fail << "unknown special configuration name '" << s << "' in "
                   << "config.config.load";
          }
        }
      }

      // Cache the config.config.persist value, if any.
      //
      if (mod != nullptr)
      {
        static_cast<module&> (*mod).persist =
          cast_null<vector<pair<string, string>>> (
            rs["config.config.persist"]);
      }

      // Register alias and fallback rule for the configure meta-operation.
      //
      // We need this rule for out-of-any-project dependencies (e.g.,
      // libraries imported from /usr/lib). We are registring it on the
      // global scope similar to builtin rules.
      //
      rs.global_scope ().insert_rule<mtime_target> (
        configure_id, 0, "config.file", file_rule::instance);

      //@@ outer
      rs.insert_rule<alias> (configure_id, 0, "config.alias", alias_rule::instance);

      // This allows a custom configure rule while doing nothing by default.
      //
      rs.insert_rule<target> (configure_id, 0, "config", noop_rule::instance);
      rs.insert_rule<file> (configure_id, 0, "config.file", noop_rule::instance);

      return true;
    }

    static const module_functions mod_functions[] =
    {
      {"config", &boot,   &init},
      {nullptr,  nullptr, nullptr}
    };

    const module_functions*
    build2_config_load ()
    {
      // Initialize the config entry points in the build system core.
      //
      config_save_variable = &save_variable;
      config_preprocess_create = &preprocess_create;

      return mod_functions;
    }
  }
}