gold/gold.cc

   1 // ld.c -- linker main function
   2
   3 #include "gold.h"
   4
   5 #include <cstdlib>
   6 #include <cstdio>
   7 #include <cstring>
   8 #include <unistd.h>
   9
  10 #include "options.h"
  11 #include "workqueue.h"
  12 #include "dirsearch.h"
  13 #include "readsyms.h"
  14 #include "symtab.h"
  15 #include "common.h"
  16 #include "object.h"
  17 #include "layout.h"
  18 #include "reloc.h"
  19 #include "defstd.h"
  20
  21 namespace gold
  22 {
  23
  24 const char* program_name;
  25
  26 void
  27 gold_exit(bool status)
  28 {
  29   exit(status ? EXIT_SUCCESS : EXIT_FAILURE);
  30 }
  31
  32 void
  33 gold_fatal(const char* msg, bool perrno)
  34 {
  35   fprintf(stderr, "%s: ", program_name);
  36   if (perrno)
  37     perror(msg);
  38   else
  39     fprintf(stderr, "%s\n", msg);
  40   gold_exit(false);
  41 }
  42
  43 void
  44 gold_nomem()
  45 {
  46   // We are out of memory, so try hard to print a reasonable message.
  47   // Note that we don't try to translate this message, since the
  48   // translation process itself will require memory.
  49   write(2, program_name, strlen(program_name));
  50   const char* const s = ": out of memory\n";
  51   write(2, s, strlen(s));
  52   gold_exit(false);
  53 }
  54
  55 void
  56 gold_unreachable()
  57 {
  58   abort();
  59 }
  60
  61 // This class arranges to run the functions done in the middle of the
  62 // link.  It is just a closure.
  63
  64 class Middle_runner : public Task_function_runner
  65 {
  66  public:
  67   Middle_runner(const General_options& options,
  68                 const Input_objects* input_objects,
  69                 Symbol_table* symtab,
  70                 Layout* layout)
  71     : options_(options), input_objects_(input_objects), symtab_(symtab),
  72       layout_(layout)
  73   { }
  74
  75   void
  76   run(Workqueue*);
  77
  78  private:
  79   const General_options& options_;
  80   const Input_objects* input_objects_;
  81   Symbol_table* symtab_;
  82   Layout* layout_;
  83 };
  84
  85 void
  86 Middle_runner::run(Workqueue* workqueue)
  87 {
  88   queue_middle_tasks(this->options_, this->input_objects_, this->symtab_,
  89                      this->layout_, workqueue);
  90 }
  91
  92 // Queue up the initial set of tasks for this link job.
  93
  94 void
  95 queue_initial_tasks(const General_options& options,
  96                     const Dirsearch& search_path,
  97                     const Command_line& cmdline,
  98                     Workqueue* workqueue, Input_objects* input_objects,
  99                     Symbol_table* symtab, Layout* layout)
 100 {
 101   if (cmdline.begin() == cmdline.end())
 102     gold_fatal(_("no input files"), false);
 103
 104   // Read the input files.  We have to add the symbols to the symbol
 105   // table in order.  We do this by creating a separate blocker for
 106   // each input file.  We associate the blocker with the following
 107   // input file, to give us a convenient place to delete it.
 108   Task_token* this_blocker = NULL;
 109   for (Command_line::const_iterator p = cmdline.begin();
 110        p != cmdline.end();
 111        ++p)
 112     {
 113       Task_token* next_blocker = new Task_token();
 114       next_blocker->add_blocker();
 115       workqueue->queue(new Read_symbols(options, input_objects, symtab, layout,
 116                                         search_path, &*p, NULL, this_blocker,
 117                                         next_blocker));
 118       this_blocker = next_blocker;
 119     }
 120
 121   workqueue->queue(new Task_function(new Middle_runner(options,
 122                                                        input_objects,
 123                                                        symtab,
 124                                                        layout),
 125                                      this_blocker));
 126 }
 127
 128 // Queue up the middle set of tasks.  These are the tasks which run
 129 // after all the input objects have been found and all the symbols
 130 // have been read, but before we lay out the output file.
 131
 132 void
 133 queue_middle_tasks(const General_options& options,
 134                    const Input_objects* input_objects,
 135                    Symbol_table* symtab,
 136                    Layout* layout,
 137                    Workqueue* workqueue)
 138 {
 139   // Predefine standard symbols.  This should be fast, so we don't
 140   // bother to create a task for it.
 141   define_standard_symbols(symtab, layout, input_objects->target());
 142
 143   // Read the relocations of the input files.  We do this to find
 144   // which symbols are used by relocations which require a GOT and/or
 145   // a PLT entry, or a COPY reloc.  When we implement garbage
 146   // collection we will do it here by reading the relocations in a
 147   // breadth first search by references.
 148   //
 149   // We could also read the relocations during the first pass, and
 150   // mark symbols at that time.  That is how the old GNU linker works.
 151   // Doing that is more complex, since we may later decide to discard
 152   // some of the sections, and thus change our minds about the types
 153   // of references made to the symbols.
 154   Task_token* blocker = new Task_token();
 155   Task_token* symtab_lock = new Task_token();
 156   for (Input_objects::Relobj_iterator p = input_objects->relobj_begin();
 157        p != input_objects->relobj_end();
 158        ++p)
 159     {
 160       // We can read and process the relocations in any order.  But we
 161       // only want one task to write to the symbol table at a time.
 162       // So we queue up a task for each object to read the
 163       // relocations.  That task will in turn queue a task to wait
 164       // until it can write to the symbol table.
 165       blocker->add_blocker();
 166       workqueue->queue(new Read_relocs(options, symtab, layout, *p,
 167                                        symtab_lock, blocker));
 168     }
 169
 170   // Allocate common symbols.  This requires write access to the
 171   // symbol table, but is independent of the relocation processing.
 172   blocker->add_blocker();
 173   workqueue->queue(new Allocate_commons_task(options, symtab, layout,
 174                                              symtab_lock, blocker));
 175
 176   // When all those tasks are complete, we can start laying out the
 177   // output file.
 178   workqueue->queue(new Task_function(new Layout_task_runner(options,
 179                                                             input_objects,
 180                                                             symtab,
 181                                                             layout),
 182                                      blocker));
 183 }
 184
 185 // Queue up the final set of tasks.  This is called at the end of
 186 // Layout_task.
 187
 188 void
 189 queue_final_tasks(const General_options& options,
 190                   const Input_objects* input_objects,
 191                   const Symbol_table* symtab,
 192                   const Layout* layout,
 193                   Workqueue* workqueue,
 194                   Output_file* of)
 195 {
 196   // Use a blocker to block the final cleanup task.
 197   Task_token* final_blocker = new Task_token();
 198
 199   // Queue a task for each input object to relocate the sections and
 200   // write out the local symbols.
 201   for (Input_objects::Relobj_iterator p = input_objects->relobj_begin();
 202        p != input_objects->relobj_end();
 203        ++p)
 204     {
 205       final_blocker->add_blocker();
 206       workqueue->queue(new Relocate_task(options, symtab, layout, *p, of,
 207                                          final_blocker));
 208     }
 209
 210   // Queue a task to write out the symbol table.
 211   final_blocker->add_blocker();
 212   workqueue->queue(new Write_symbols_task(symtab, input_objects->target(),
 213                                           layout->sympool(), of,
 214                                           final_blocker));
 215
 216   // Queue a task to write out everything else.
 217   final_blocker->add_blocker();
 218   workqueue->queue(new Write_data_task(layout, of, final_blocker));
 219
 220   // Queue a task to close the output file.  This will be blocked by
 221   // FINAL_BLOCKER.
 222   workqueue->queue(new Task_function(new Close_task_runner(of),
 223                                      final_blocker));
 224 }
 225
 226 } // End namespace gold.
 227
 228 using namespace gold;
 229
 230 int
 231 main(int argc, char** argv)
 232 {
 233 #if defined (HAVE_SETLOCALE) && defined (HAVE_LC_MESSAGES)
 234   setlocale (LC_MESSAGES, "");
 235 #endif
 236 #if defined (HAVE_SETLOCALE)
 237   setlocale (LC_CTYPE, "");
 238 #endif
 239   bindtextdomain (PACKAGE, LOCALEDIR);
 240   textdomain (PACKAGE);
 241
 242   gold::program_name = argv[0];
 243
 244   // Handle the command line options.
 245   gold::Command_line command_line;
 246   command_line.process(argc - 1, argv + 1);
 247
 248   // The work queue.
 249   gold::Workqueue workqueue(command_line.options());
 250
 251   // The list of input objects.
 252   Input_objects input_objects;
 253
 254   // The symbol table.
 255   Symbol_table symtab;
 256
 257   // The layout object.
 258   Layout layout(command_line.options());
 259
 260   // Get the search path from the -L options.
 261   Dirsearch search_path;
 262   search_path.add(&workqueue, command_line.options().search_path());
 263
 264   // Queue up the first set of tasks.
 265   queue_initial_tasks(command_line.options(), search_path,
 266                       command_line, &workqueue, &input_objects,
 267                       &symtab, &layout);
 268
 269   // Run the main task processing loop.
 270   workqueue.process();
 271
 272   gold::gold_exit(true);
 273 }