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/* simple-object.h -- simple routines to read and write object files

   Copyright 2010 Free Software Foundation, Inc.

   Written by Ian Lance Taylor, Google.

This program is free software; you can redistribute it and/or modify it

under the terms of the GNU General Public License as published by the

Free Software Foundation; either version 2, or (at your option) any

later version.

This program is distributed in the hope that it will be useful,

but WITHOUT ANY WARRANTY; without even the implied warranty of

MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

GNU General Public License for more details.

You should have received a copy of the GNU General Public License

along with this program; if not, write to the Free Software

Foundation, 51 Franklin Street - Fifth Floor,

Boston, MA 02110-1301, USA.  */

#ifndef SIMPLE_OBJECT_H

#define SIMPLE_OBJECT_H

#include <stddef.h>

#include <sys/types.h>

#ifdef HAVE_UNISTD_H

#include <unistd.h>

#endif

#ifdef __cplusplus

extern "C" {

#endif

/* This header file provides four types with associated functions.

   They are used to read and write object files.  This is a minimal

   interface, intended to support the needs of gcc without bringing in

   all the power and complexity of BFD.  */

/* The type simple_object_read * is used to read an existing object

   file.  */

typedef struct simple_object_read_struct simple_object_read;

/* Create an simple_object_read given DESCRIPTOR, an open file

   descriptor, and OFFSET, an offset within the file.  The offset is

   for use with archives, and should be 0 for an ordinary object file.

   The descriptor must remain open until done with the returned

   simple_object_read.  SEGMENT_NAME is used on Mach-O and is required

   on that platform: it means to only look at sections within the

   segment with that name.  It is ignored for other object file

   formats.  On error, this function returns NULL, and sets *ERRMSG to

   an error string and sets *ERR to an errno value or 0 if there is no

   relevant errno.  */

extern simple_object_read *

simple_object_start_read (int descriptor, off_t offset,

                          const char *segment_name, const char **errmsg,

                          int *err);

/* Call PFN for each section in SIMPLE_OBJECT, passing it the section

   name, offset within the file of the section contents, and length of

   the section contents.  The offset within the file is relative to

   the offset passed to simple_object_start_read.  The DATA argument

   to simple_object_find_sections is passed on to PFN.  If PFN returns

   0, the loop is stopped and simple_object_find_sections returns.  If

   PFN returns non-zero, the loop continues.  On success this returns

   NULL.  On error it returns an error string, and sets *ERR to an

   errno value or 0 if there is no relevant errno.  */

extern const char *

simple_object_find_sections (simple_object_read *simple_object,

                             int (*pfn) (void *data, const char *,

                                         off_t offset, off_t length),

                             void *data,

                             int *err);

/* Look for the section NAME in SIMPLE_OBJECT.  This returns

   information for the first section NAME in SIMPLE_OBJECT.  Note that

   calling this multiple times is inefficient; use

   simple_object_find_sections instead.

   If found, return 1 and set *OFFSET to the offset in the file of the

   section contents and set *LENGTH to the length of the section

   contents.  *OFFSET will be relative to the offset passed to

   simple_object_start_read.

   If the section is not found, and no error occurs, return 0 and set

   *ERRMSG to NULL.

   If an error occurs, return 0, set *ERRMSG to an error message, and

   set *ERR to an errno value or 0 if there is no relevant errno.  */

extern int

simple_object_find_section (simple_object_read *simple_object,

                            const char *name, off_t *offset, off_t *length,

                            const char **errmsg, int *err);

/* Release all resources associated with SIMPLE_OBJECT.  This does not

   close the file descriptor.  */

extern void

simple_object_release_read (simple_object_read *);

/* The type simple_object_attributes holds the attributes of an object

   file that matter for creating a file or ensuring that two files are

   compatible.  This is a set of magic numbers.  */

typedef struct simple_object_attributes_struct simple_object_attributes;

/* Fetch the attributes of SIMPLE_OBJECT.  This information will

   persist until simple_object_attributes_release is called, even if

   SIMPLE_OBJECT is closed.  On error this returns NULL, sets *ERRMSG

   to an error message, and sets *ERR to an errno value or 0 if there

   isn't one.  */

extern simple_object_attributes *

simple_object_fetch_attributes (simple_object_read *simple_object,

                                const char **errmsg, int *err);

/* Merge the FROM attributes into TO.  If two objects with these

   attributes could be linked together without error, returns NULL.

   Otherwise, returns an error message, and sets *ERR to an errno

   value or 0 if there isn't one.  */

extern const char *

simple_object_attributes_merge (simple_object_attributes *to,

                                simple_object_attributes *from,

                                int *err);

/* Release all resources associated with ATTRS.  */

extern void

simple_object_release_attributes (simple_object_attributes *attrs);

/* The type simple_object_write is used to create a new object file.  */

typedef struct simple_object_write_struct simple_object_write;

/* Start creating a new object file which is like ATTRS.  You must

   fetch attribute information from an existing object file before you

   can create a new one.  There is currently no support for creating

   an object file de novo.  The segment name is only used on Mach-O,

   where it is required.  It means that all sections are created

   within that segment.  It is ignored for other object file formats.

   On error this function returns NULL, sets *ERRMSG to an error

   message, and sets *ERR to an errno value or 0 if there isn't

   one.  */

extern simple_object_write *

simple_object_start_write (simple_object_attributes *attrs,

                           const char *segment_name,

                           const char **errmsg, int *err);

/* The type simple_object_write_section is a handle for a section

   which is being written.  */

typedef struct simple_object_write_section_struct simple_object_write_section;

/* Add a section to SIMPLE_OBJECT.  NAME is the name of the new

   section.  ALIGN is the required alignment expressed as the number

   of required low-order 0 bits (e.g., 2 for alignment to a 32-bit

   boundary).  The section is created as containing data, readable,

   not writable, not executable, not loaded at runtime.  On error this

   returns NULL, sets *ERRMSG to an error message, and sets *ERR to an

   errno value or 0 if there isn't one.  */

extern simple_object_write_section *

simple_object_write_create_section (simple_object_write *simple_object,

                                    const char *name, unsigned int align,

                                    const char **errmsg, int *err);

/* Add data BUFFER/SIZE to SECTION in SIMPLE_OBJECT.  If COPY is

   non-zero, the data will be copied into memory if necessary.  If

   COPY is zero, BUFFER must persist until SIMPLE_OBJECT is released.

   On success this returns NULL.  On error this returns an error

   message, and sets *ERR to an errno value or 0 if there isn't

   one.  */

extern const char *

simple_object_write_add_data (simple_object_write *simple_object,

                              simple_object_write_section *section,

                              const void *buffer, size_t size,

                              int copy, int *err);

/* Write the complete object file to DESCRIPTOR, an open file

   descriptor.  This returns NULL on success.  On error this returns

   an error message, and sets *ERR to an errno value or 0 if there

   isn't one.  */

extern const char *

simple_object_write_to_file (simple_object_write *simple_object,

                             int descriptor, int *err);

/* Release all resources associated with SIMPLE_OBJECT, including any

   simple_object_write_section's that may have been created.  */

extern void

simple_object_release_write (simple_object_write *);

#ifdef __cplusplus

}

#endif

#endif