1 /* simple-object.h -- simple routines to read and write object files
2 Copyright (C) 2010-2023 Free Software Foundation, Inc.
3 Written by Ian Lance Taylor, Google.
4
5 This program is free software; you can redistribute it and/or modify it
6 under the terms of the GNU General Public License as published by the
7 Free Software Foundation; either version 2, or (at your option) any
8 later version.
9
10 This program is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 GNU General Public License for more details.
14
15 You should have received a copy of the GNU General Public License
16 along with this program; if not, write to the Free Software
17 Foundation, 51 Franklin Street - Fifth Floor,
18 Boston, MA 02110-1301, USA. */
19
20 #ifndef SIMPLE_OBJECT_H
21 #define SIMPLE_OBJECT_H
22
23 #include <stddef.h>
24 #include <sys/types.h>
25
26 #ifdef HAVE_UNISTD_H
27 #include <unistd.h>
28 #endif
29
30 #ifdef __cplusplus
31 extern "C" {
32 #endif
33
34 /* This header file provides four types with associated functions.
35 They are used to read and write object files. This is a minimal
36 interface, intended to support the needs of gcc without bringing in
37 all the power and complexity of BFD. */
38
39 /* The type simple_object_read * is used to read an existing object
40 file. */
41
42 typedef struct simple_object_read_struct simple_object_read;
43
44 /* Create an simple_object_read given DESCRIPTOR, an open file
45 descriptor, and OFFSET, an offset within the file. The offset is
46 for use with archives, and should be 0 for an ordinary object file.
47 The descriptor must remain open until done with the returned
48 simple_object_read. SEGMENT_NAME is used on Mach-O and is required
49 on that platform: it means to only look at sections within the
50 segment with that name. It is ignored for other object file
51 formats. On error, this function returns NULL, and sets *ERRMSG to
52 an error string and sets *ERR to an errno value or 0 if there is no
53 relevant errno. */
54
55 extern simple_object_read *
56 simple_object_start_read (int descriptor, off_t offset,
57 const char *segment_name, const char **errmsg,
58 int *err);
59
60 /* Call PFN for each section in SIMPLE_OBJECT, passing it the section
61 name, offset within the file of the section contents, and length of
62 the section contents. The offset within the file is relative to
63 the offset passed to simple_object_start_read. The DATA argument
64 to simple_object_find_sections is passed on to PFN. If PFN returns
65 0, the loop is stopped and simple_object_find_sections returns. If
66 PFN returns non-zero, the loop continues. On success this returns
67 NULL. On error it returns an error string, and sets *ERR to an
68 errno value or 0 if there is no relevant errno. */
69
70 extern const char *
71 simple_object_find_sections (simple_object_read *simple_object,
72 int (*pfn) (void *data, const char *,
73 off_t offset, off_t length),
74 void *data,
75 int *err);
76
77 /* Look for the section NAME in SIMPLE_OBJECT. This returns
78 information for the first section NAME in SIMPLE_OBJECT. Note that
79 calling this multiple times is inefficient; use
80 simple_object_find_sections instead.
81
82 If found, return 1 and set *OFFSET to the offset in the file of the
83 section contents and set *LENGTH to the length of the section
84 contents. *OFFSET will be relative to the offset passed to
85 simple_object_start_read.
86
87 If the section is not found, and no error occurs, return 0 and set
88 *ERRMSG to NULL.
89
90 If an error occurs, return 0, set *ERRMSG to an error message, and
91 set *ERR to an errno value or 0 if there is no relevant errno. */
92
93 extern int
94 simple_object_find_section (simple_object_read *simple_object,
95 const char *name, off_t *offset, off_t *length,
96 const char **errmsg, int *err);
97
98 /* Release all resources associated with SIMPLE_OBJECT. This does not
99 close the file descriptor. */
100
101 extern void
102 simple_object_release_read (simple_object_read *);
103
104 /* The type simple_object_attributes holds the attributes of an object
105 file that matter for creating a file or ensuring that two files are
106 compatible. This is a set of magic numbers. */
107
108 typedef struct simple_object_attributes_struct simple_object_attributes;
109
110 /* Fetch the attributes of SIMPLE_OBJECT. This information will
111 persist until simple_object_attributes_release is called, even if
112 SIMPLE_OBJECT is closed. On error this returns NULL, sets *ERRMSG
113 to an error message, and sets *ERR to an errno value or 0 if there
114 isn't one. */
115
116 extern simple_object_attributes *
117 simple_object_fetch_attributes (simple_object_read *simple_object,
118 const char **errmsg, int *err);
119
120 /* Merge the FROM attributes into TO. If two objects with these
121 attributes could be linked together without error, returns NULL.
122 Otherwise, returns an error message, and sets *ERR to an errno
123 value or 0 if there isn't one. */
124
125 extern const char *
126 simple_object_attributes_merge (simple_object_attributes *to,
127 simple_object_attributes *from,
128 int *err);
129
130 /* Release all resources associated with ATTRS. */
131
132 extern void
133 simple_object_release_attributes (simple_object_attributes *attrs);
134
135 /* The type simple_object_write is used to create a new object file. */
136
137 typedef struct simple_object_write_struct simple_object_write;
138
139 /* Start creating a new object file which is like ATTRS. You must
140 fetch attribute information from an existing object file before you
141 can create a new one. There is currently no support for creating
142 an object file de novo. The segment name is only used on Mach-O,
143 where it is required. It means that all sections are created
144 within that segment. It is ignored for other object file formats.
145 On error this function returns NULL, sets *ERRMSG to an error
146 message, and sets *ERR to an errno value or 0 if there isn't
147 one. */
148
149 extern simple_object_write *
150 simple_object_start_write (simple_object_attributes *attrs,
151 const char *segment_name,
152 const char **errmsg, int *err);
153
154 /* The type simple_object_write_section is a handle for a section
155 which is being written. */
156
157 typedef struct simple_object_write_section_struct simple_object_write_section;
158
159 /* Add a section to SIMPLE_OBJECT. NAME is the name of the new
160 section. ALIGN is the required alignment expressed as the number
161 of required low-order 0 bits (e.g., 2 for alignment to a 32-bit
162 boundary). The section is created as containing data, readable,
163 not writable, not executable, not loaded at runtime. On error this
164 returns NULL, sets *ERRMSG to an error message, and sets *ERR to an
165 errno value or 0 if there isn't one. */
166
167 extern simple_object_write_section *
168 simple_object_write_create_section (simple_object_write *simple_object,
169 const char *name, unsigned int align,
170 const char **errmsg, int *err);
171
172 /* Add data BUFFER/SIZE to SECTION in SIMPLE_OBJECT. If COPY is
173 non-zero, the data will be copied into memory if necessary. If
174 COPY is zero, BUFFER must persist until SIMPLE_OBJECT is released.
175 On success this returns NULL. On error this returns an error
176 message, and sets *ERR to an errno value or 0 if there isn't
177 one. */
178
179 extern const char *
180 simple_object_write_add_data (simple_object_write *simple_object,
181 simple_object_write_section *section,
182 const void *buffer, size_t size,
183 int copy, int *err);
184
185 /* Write the complete object file to DESCRIPTOR, an open file
186 descriptor. This returns NULL on success. On error this returns
187 an error message, and sets *ERR to an errno value or 0 if there
188 isn't one. */
189
190 extern const char *
191 simple_object_write_to_file (simple_object_write *simple_object,
192 int descriptor, int *err);
193
194 /* Release all resources associated with SIMPLE_OBJECT, including any
195 simple_object_write_section's that may have been created. */
196
197 extern void
198 simple_object_release_write (simple_object_write *);
199
200 /* Copy LTO debug sections from SRC_OBJECT to DEST.
201 If RENAME is true, rename LTO debug section into debug section (i.e.
202 when producing final binary) and if it is false, keep the sections with
203 original names (when incrementally linking).
204 If an error occurs, return the errno value in ERR and an error string. */
205
206 extern const char *
207 simple_object_copy_lto_debug_sections (simple_object_read *src_object,
208 const char *dest,
209 int *err, int rename);
210
211 #ifdef __cplusplus
212 }
213 #endif
214
215 #endif