1// target-select.cc -- select a target for an object file
2
3// Copyright (C) 2006-2017 Free Software Foundation, Inc.
4// Written by Ian Lance Taylor <iant@google.com>.
5
6// This file is part of gold.
7
8// This program is free software; you can redistribute it and/or modify
9// it under the terms of the GNU General Public License as published by
10// the Free Software Foundation; either version 3 of the License, or
11// (at your option) any later version.
12
13// This program is distributed in the hope that it will be useful,
14// but WITHOUT ANY WARRANTY; without even the implied warranty of
15// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
16// GNU General Public License for more details.
17
18// You should have received a copy of the GNU General Public License
19// along with this program; if not, write to the Free Software
20// Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
21// MA 02110-1301, USA.
22
23#include "gold.h"
24
25#include <cstdio>
26#include <cstring>
27
28#include "elfcpp.h"
29#include "options.h"
30#include "parameters.h"
31#include "target-select.h"
32
33namespace
34{
35
36// The start of the list of target selectors.
37
38gold::Target_selector* target_selectors;
39
40} // End anonymous namespace.
41
42namespace gold
43{
44
45// Class Set_target_once.
46
47void
48Set_target_once::do_run_once(void*)
49{
50  this->target_selector_->set_target();
51}
52
53// Construct a Target_selector, which means adding it to the linked
54// list.  This runs at global constructor time, so we want it to be
55// fast.
56
57Target_selector::Target_selector(int machine, int size, bool is_big_endian,
58				 const char* bfd_name, const char* emulation)
59  : machine_(machine), size_(size), is_big_endian_(is_big_endian),
60    bfd_name_(bfd_name), emulation_(emulation), instantiated_target_(NULL),
61    set_target_once_(this)
62{
63  this->next_ = target_selectors;
64  target_selectors = this;
65}
66
67// Instantiate the target and return it.  Use SET_TARGET_ONCE_ to
68// avoid instantiating two instances of the same target.
69
70Target*
71Target_selector::instantiate_target()
72{
73  this->set_target_once_.run_once(NULL);
74  return this->instantiated_target_;
75}
76
77// Instantiate the target.  This is called at most once.
78
79void
80Target_selector::set_target()
81{
82  gold_assert(this->instantiated_target_ == NULL);
83  this->instantiated_target_ = this->do_instantiate_target();
84}
85
86// If we instantiated TARGET, return the corresponding BFD name.
87
88const char*
89Target_selector::do_target_bfd_name(const Target* target)
90{
91  if (!this->is_our_target(target))
92    return NULL;
93  const char* my_bfd_name = this->bfd_name();
94  gold_assert(my_bfd_name != NULL);
95  return my_bfd_name;
96}
97
98// Find the target for an ELF file.
99
100Target*
101select_target(Input_file* input_file, off_t offset,
102	      int machine, int size, bool is_big_endian,
103	      int osabi, int abiversion)
104{
105  for (Target_selector* p = target_selectors; p != NULL; p = p->next())
106    {
107      int pmach = p->machine();
108      if ((pmach == machine || pmach == elfcpp::EM_NONE)
109	  && p->get_size() == size
110	  && (p->is_big_endian() ? is_big_endian : !is_big_endian))
111	{
112	  Target* ret = p->recognize(input_file, offset,
113				     machine, osabi, abiversion);
114	  if (ret != NULL)
115	    return ret;
116	}
117    }
118  return NULL;
119}
120
121// Find a target using a BFD name.  This is used to support the
122// --oformat option.
123
124Target*
125select_target_by_bfd_name(const char* name)
126{
127  for (Target_selector* p = target_selectors; p != NULL; p = p->next())
128    {
129      const char* pname = p->bfd_name();
130      if (pname == NULL || strcmp(pname, name) == 0)
131	{
132	  Target* ret = p->recognize_by_bfd_name(name);
133	  if (ret != NULL)
134	    return ret;
135	}
136    }
137  return NULL;
138}
139
140// Find a target using a GNU linker emulation.  This is used to
141// support the -m option.
142
143Target*
144select_target_by_emulation(const char* name)
145{
146  for (Target_selector* p = target_selectors; p != NULL; p = p->next())
147    {
148      const char* pname = p->emulation();
149      if (pname == NULL || strcmp(pname, name) == 0)
150	{
151	  Target* ret = p->recognize_by_emulation(name);
152	  if (ret != NULL)
153	    return ret;
154	}
155    }
156  return NULL;
157}
158
159// Push all the supported BFD names onto a vector.
160
161void
162supported_target_names(std::vector<const char*>* names)
163{
164  for (Target_selector* p = target_selectors; p != NULL; p = p->next())
165    p->supported_bfd_names(names);
166}
167
168// Push all the supported emulations onto a vector.
169
170void
171supported_emulation_names(std::vector<const char*>* names)
172{
173  for (Target_selector* p = target_selectors; p != NULL; p = p->next())
174    p->supported_emulations(names);
175}
176
177// Implement the --print-output-format option.
178
179void
180print_output_format()
181{
182  if (!parameters->target_valid())
183    {
184      // This case arises when --print-output-format is used with no
185      // input files.  We need to come up with the right string to
186      // print based on the other options.  If the user specified the
187      // format using a --oformat option, use that.  That saves each
188      // target from having to remember the name that was used to
189      // select it.  In other cases, we will just have to ask the
190      // target.
191      if (parameters->options().user_set_oformat())
192	{
193	  const char* bfd_name = parameters->options().oformat();
194	  Target* target = select_target_by_bfd_name(bfd_name);
195	  if (target != NULL)
196	    printf("%s\n", bfd_name);
197	  else
198	    gold_error(_("unrecognized output format %s"), bfd_name);
199	  return;
200	}
201
202      parameters_force_valid_target();
203    }
204
205  const Target* target = &parameters->target();
206  for (Target_selector* p = target_selectors; p != NULL; p = p->next())
207    {
208      const char* bfd_name = p->target_bfd_name(target);
209      if (bfd_name != NULL)
210	{
211	  printf("%s\n", bfd_name);
212	  return;
213	}
214    }
215
216  gold_unreachable();
217}
218
219} // End namespace gold.
220