213 lines
8.1 KiB
C
213 lines
8.1 KiB
C
/* simple-object.h -- simple routines to read and write object files
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Copyright (C) 2010-2018 Free Software Foundation, Inc.
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Written by Ian Lance Taylor, Google.
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This program is free software; you can redistribute it and/or modify it
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under the terms of the GNU General Public License as published by the
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Free Software Foundation; either version 2, or (at your option) any
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later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, 51 Franklin Street - Fifth Floor,
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Boston, MA 02110-1301, USA. */
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#ifndef SIMPLE_OBJECT_H
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#define SIMPLE_OBJECT_H
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#include <stddef.h>
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#include <sys/types.h>
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#ifdef HAVE_UNISTD_H
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#include <unistd.h>
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#endif
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#ifdef __cplusplus
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extern "C" {
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#endif
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/* This header file provides four types with associated functions.
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They are used to read and write object files. This is a minimal
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interface, intended to support the needs of gcc without bringing in
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all the power and complexity of BFD. */
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/* The type simple_object_read * is used to read an existing object
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file. */
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typedef struct simple_object_read_struct simple_object_read;
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/* Create an simple_object_read given DESCRIPTOR, an open file
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descriptor, and OFFSET, an offset within the file. The offset is
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for use with archives, and should be 0 for an ordinary object file.
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The descriptor must remain open until done with the returned
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simple_object_read. SEGMENT_NAME is used on Mach-O and is required
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on that platform: it means to only look at sections within the
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segment with that name. It is ignored for other object file
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formats. On error, this function returns NULL, and sets *ERRMSG to
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an error string and sets *ERR to an errno value or 0 if there is no
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relevant errno. */
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extern simple_object_read *
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simple_object_start_read (int descriptor, off_t offset,
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const char *segment_name, const char **errmsg,
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int *err);
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/* Call PFN for each section in SIMPLE_OBJECT, passing it the section
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name, offset within the file of the section contents, and length of
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the section contents. The offset within the file is relative to
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the offset passed to simple_object_start_read. The DATA argument
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to simple_object_find_sections is passed on to PFN. If PFN returns
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0, the loop is stopped and simple_object_find_sections returns. If
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PFN returns non-zero, the loop continues. On success this returns
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NULL. On error it returns an error string, and sets *ERR to an
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errno value or 0 if there is no relevant errno. */
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extern const char *
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simple_object_find_sections (simple_object_read *simple_object,
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int (*pfn) (void *data, const char *,
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off_t offset, off_t length),
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void *data,
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int *err);
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/* Look for the section NAME in SIMPLE_OBJECT. This returns
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information for the first section NAME in SIMPLE_OBJECT. Note that
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calling this multiple times is inefficient; use
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simple_object_find_sections instead.
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If found, return 1 and set *OFFSET to the offset in the file of the
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section contents and set *LENGTH to the length of the section
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contents. *OFFSET will be relative to the offset passed to
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simple_object_start_read.
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If the section is not found, and no error occurs, return 0 and set
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*ERRMSG to NULL.
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If an error occurs, return 0, set *ERRMSG to an error message, and
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set *ERR to an errno value or 0 if there is no relevant errno. */
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extern int
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simple_object_find_section (simple_object_read *simple_object,
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const char *name, off_t *offset, off_t *length,
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const char **errmsg, int *err);
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/* Release all resources associated with SIMPLE_OBJECT. This does not
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close the file descriptor. */
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extern void
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simple_object_release_read (simple_object_read *);
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/* The type simple_object_attributes holds the attributes of an object
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file that matter for creating a file or ensuring that two files are
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compatible. This is a set of magic numbers. */
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typedef struct simple_object_attributes_struct simple_object_attributes;
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/* Fetch the attributes of SIMPLE_OBJECT. This information will
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persist until simple_object_attributes_release is called, even if
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SIMPLE_OBJECT is closed. On error this returns NULL, sets *ERRMSG
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to an error message, and sets *ERR to an errno value or 0 if there
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isn't one. */
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extern simple_object_attributes *
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simple_object_fetch_attributes (simple_object_read *simple_object,
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const char **errmsg, int *err);
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/* Merge the FROM attributes into TO. If two objects with these
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attributes could be linked together without error, returns NULL.
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Otherwise, returns an error message, and sets *ERR to an errno
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value or 0 if there isn't one. */
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extern const char *
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simple_object_attributes_merge (simple_object_attributes *to,
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simple_object_attributes *from,
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int *err);
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/* Release all resources associated with ATTRS. */
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extern void
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simple_object_release_attributes (simple_object_attributes *attrs);
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/* The type simple_object_write is used to create a new object file. */
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typedef struct simple_object_write_struct simple_object_write;
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/* Start creating a new object file which is like ATTRS. You must
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fetch attribute information from an existing object file before you
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can create a new one. There is currently no support for creating
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an object file de novo. The segment name is only used on Mach-O,
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where it is required. It means that all sections are created
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within that segment. It is ignored for other object file formats.
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On error this function returns NULL, sets *ERRMSG to an error
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message, and sets *ERR to an errno value or 0 if there isn't
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one. */
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extern simple_object_write *
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simple_object_start_write (simple_object_attributes *attrs,
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const char *segment_name,
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const char **errmsg, int *err);
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/* The type simple_object_write_section is a handle for a section
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which is being written. */
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typedef struct simple_object_write_section_struct simple_object_write_section;
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/* Add a section to SIMPLE_OBJECT. NAME is the name of the new
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section. ALIGN is the required alignment expressed as the number
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of required low-order 0 bits (e.g., 2 for alignment to a 32-bit
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boundary). The section is created as containing data, readable,
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not writable, not executable, not loaded at runtime. On error this
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returns NULL, sets *ERRMSG to an error message, and sets *ERR to an
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errno value or 0 if there isn't one. */
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extern simple_object_write_section *
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simple_object_write_create_section (simple_object_write *simple_object,
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const char *name, unsigned int align,
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const char **errmsg, int *err);
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/* Add data BUFFER/SIZE to SECTION in SIMPLE_OBJECT. If COPY is
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non-zero, the data will be copied into memory if necessary. If
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COPY is zero, BUFFER must persist until SIMPLE_OBJECT is released.
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On success this returns NULL. On error this returns an error
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message, and sets *ERR to an errno value or 0 if there isn't
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one. */
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extern const char *
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simple_object_write_add_data (simple_object_write *simple_object,
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simple_object_write_section *section,
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const void *buffer, size_t size,
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int copy, int *err);
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/* Write the complete object file to DESCRIPTOR, an open file
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descriptor. This returns NULL on success. On error this returns
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an error message, and sets *ERR to an errno value or 0 if there
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isn't one. */
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extern const char *
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simple_object_write_to_file (simple_object_write *simple_object,
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int descriptor, int *err);
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/* Release all resources associated with SIMPLE_OBJECT, including any
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simple_object_write_section's that may have been created. */
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extern void
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simple_object_release_write (simple_object_write *);
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/* Copy LTO debug sections from SRC_OBJECT to DEST.
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If an error occurs, return the errno value in ERR and an error string. */
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extern const char *
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simple_object_copy_lto_debug_sections (simple_object_read *src_object,
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const char *dest,
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int *err);
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#ifdef __cplusplus
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}
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#endif
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#endif
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