1 // target-select.cc -- select a target for an object file
2 
3 // Copyright (C) 2006-2016 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 
33 namespace
34 {
35 
36 // The start of the list of target selectors.
37 
38 gold::Target_selector* target_selectors;
39 
40 } // End anonymous namespace.
41 
42 namespace gold
43 {
44 
45 // Class Set_target_once.
46 
47 void
48 Set_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 
57 Target_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 
70 Target*
71 Target_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 
79 void
80 Target_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 
88 const char*
89 Target_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 
100 Target*
101 select_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 
124 Target*
125 select_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 
143 Target*
144 select_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 
161 void
162 supported_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 
170 void
171 supported_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 
179 void
180 print_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