/* Object file "section" support for the BFD library.   Copyright (C) 1990-1991 Free Software Foundation, Inc.   Written by Cygnus Support.This file is part of BFD, the Binary File Descriptor library.This program is free software; you can redistribute it and/or modifyit under the terms of the GNU General Public License as published bythe Free Software Foundation; either version 2 of the License, 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 ofMERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See theGNU General Public License for more details.You should have received a copy of the GNU General Public Licensealong with this program; if not, write to the Free SoftwareFoundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.  *//*SECTION	Sections	Sections are supported in BFD in <<section.c>>.	The raw data contained within a BFD is maintained through the	section abstraction.  A single BFD may have any number of	sections, and keeps hold of them by pointing to the first,	each one points to the next in the list.@menu@* Section Input::@* Section Output::@* typedef asection::@* section prototypes::@end menuINODESection Input, Section Output, Sections, SectionsSUBSECTION	Section Input	When a BFD is opened for reading, the section structures are	created and attached to the BFD.	Each section has a name which describes the section in the	outside world - for example, <<a.out>> would contain at least	three sections, called <<.text>>, <<.data>> and <<.bss>>. 	Sometimes a BFD will contain more than the 'natural' number of	sections. A back end may attach other sections containing	constructor data, or an application may add a section (using	bfd_make_section) to the sections attached to an already open	BFD. For example, the linker creates a supernumary section	<<COMMON>> for each input file's BFD to hold information about	common storage.	The raw data is not necessarily read in at the same time as	the section descriptor is created. Some targets may leave the	data in place until a <<bfd_get_section_contents>> call is	made. Other back ends may read in all the data at once - For	example; an S-record file has to be read once to determine the	size of the data. An IEEE-695 file doesn't contain raw data in	sections, but data and relocation expressions intermixed, so	the data area has to be parsed to get out the data and	relocations.INODESection Output, typedef asection, Section Input, SectionsSUBSECTION	Section Output	To write a new object style BFD, the various sections to be	written have to be created. They are attached to the BFD in	the same way as input sections, data is written to the	sections using <<bfd_set_section_contents>>.  	Any program that creates or combines sections (e.g., the assembler	and linker) must use the fields <<output_section>> and	<<output_offset>> to indicate the file sections to which each	section must be written.  (If the section is being created from	scratch, <<output_section>> should probably point to the section	itself, and <<output_offset>> should probably be zero.)	The data to be written comes from input sections attached to	the output sections.  The output section structure can be	considered a filter for the input section, the output section	determines the vma of the output data and the name, but the	input section determines the offset into the output section of	the data to be written.	E.g., to create a section "O", starting at 0x100, 0x123 long,	containing two subsections, "A" at offset 0x0 (ie at vma	0x100) and "B" at offset 0x20 (ie at vma 0x120) the structures	would look like:|   section name          "A"|     output_offset   0x00|     size            0x20|     output_section ----------->  section name    "O"|                             |    vma             0x100|   section name          "B" |    size            0x123|     output_offset   0x20    ||     size            0x103   ||     output_section  --------|SUBSECTION	Seglets	The data within a section is stored in a <<seglet>>.  These	are much like the fixups in <<gas>>.  The seglet abstraction	allows the a section to grow and shrink within itself.	A seglet knows how big it is, and which is the next seglet and	where the raw data for it is, and also points to a list of	relocations which apply to it.	The seglet is used by the linker to perform relaxing on final	code.  The application creates code which is as big as	necessary to make it work without relaxing, and the user can	select whether to relax.  Sometimes relaxing takes a lot of	time.  The linker runs around the relocations to see if any	are attached to data which can be shrunk, if so it does it on	a seglet by seglet basis.*/#include "bfd.h"#include "sysdep.h"#include "libbfd.h"/*DOCDDINODEtypedef asection, section prototypes, Section Output, SectionsSUBSECTION	typedef asection	The shape of a section struct:CODE_FRAGMENT..typedef struct sec .{.        {* The name of the section, the name isn't a copy, the pointer is.        the same as that passed to bfd_make_section. *}..    CONST char *name;...        {* Which section is it 0.nth      *}..   int index;                      ..        {* The next section in the list belonging to the BFD, or NULL. *}..    struct sec *next;..        {* The field flags contains attributes of the section. Some of.           flags are read in from the object file, and some are.           synthesized from other information.  *}         ..    flagword flags;..#define SEC_NO_FLAGS   0x000..        {* Tells the OS to allocate space for this section when loaded..           This would clear for a section containing debug information.           only. *}.          ..#define SEC_ALLOC      0x001.        {* Tells the OS to load the section from the file when loading..           This would be clear for a .bss section *}..#define SEC_LOAD       0x002.        {* The section contains data still to be relocated, so there will.           be some relocation information too. *}..#define SEC_RELOC      0x004..        {* Obsolete ? *}..#define SEC_BALIGN     0x008..        {* A signal to the OS that the section contains read only.          data. *}.#define SEC_READONLY   0x010..        {* The section contains code only. *}..#define SEC_CODE       0x020..        {* The section contains data only. *}..#define SEC_DATA        0x040..        {* The section will reside in ROM. *}..#define SEC_ROM        0x080..        {* The section contains constructor information. This section.           type is used by the linker to create lists of constructors and.           destructors used by <<g++>>. When a back end sees a symbol.           which should be used in a constructor list, it creates a new.           section for the type of name (eg <<__CTOR_LIST__>>), attaches.           the symbol to it and builds a relocation. To build the lists.           of constructors, all the linker has to to is catenate all the.           sections called <<__CTOR_LIST__>> and relocte the data.           contained within - exactly the operations it would peform on.           standard data. *}..#define SEC_CONSTRUCTOR 0x100..        {* The section is a constuctor, and should be placed at the.          end of the . *}...#define SEC_CONSTRUCTOR_TEXT 0x1100..#define SEC_CONSTRUCTOR_DATA 0x2100..#define SEC_CONSTRUCTOR_BSS  0x3100...        {* The section has contents - a bss section could be.           <<SEC_ALLOC>> | <<SEC_HAS_CONTENTS>>, a debug section could be.           <<SEC_HAS_CONTENTS>> *}..#define SEC_HAS_CONTENTS 0x200..        {* An instruction to the linker not to output sections.          containing this flag even if they have information which.          would normally be written. *}..#define SEC_NEVER_LOAD 0x400...       .   bfd_vma vma;.   boolean user_set_vma;..        {* The size of the section in bytes, as it will be output..           contains a value even if the section has no contents (eg, the.           size of <<.bss>>). This will be filled in after relocation *}..   bfd_size_type _cooked_size;    ..        {* The size on disk of the section in bytes originally.  Normally this.	    value is the same as the size, but if some relaxing has.	    been done, then this value will be bigger.  *}..   bfd_size_type _raw_size;    ..        {* If this section is going to be output, then this value is the.           offset into the output section of the first byte in the input.           section. Eg, if this was going to start at the 100th byte in.           the output section, this value would be 100. *}..   bfd_vma output_offset;..        {* The output section through which to map on output. *}..   struct sec *output_section;..        {* The alignment requirement of the section, as an exponent - eg.           3 aligns to 2^3 (or 8) *}..   unsigned int alignment_power;..        {* If an input section, a pointer to a vector of relocation.           records for the data in this section. *}..   struct reloc_cache_entry *relocation;..        {* If an output section, a pointer to a vector of pointers to.           relocation records for the data in this section. *}..   struct reloc_cache_entry **orelocation;..        {* The number of relocation records in one of the above  *}..   unsigned reloc_count;..        {* Information below is back end specific - and not always used.           or updated ..           File position of section data    *}..   file_ptr filepos;      .        .        {* File position of relocation info *}..   file_ptr rel_filepos;..        {* File position of line data       *}..   file_ptr line_filepos;..        {* Pointer to data for applications *}..   PTR userdata;..   struct lang_output_section *otheruserdata;..        {* Attached line number information *}..   alent *lineno;.        .        {* Number of line number records   *}..   unsigned int lineno_count;..        {* When a section is being output, this value changes as more.           linenumbers are written out *}..   file_ptr moving_line_filepos;..        {* what the section number is in the target world  *}..   int target_index;..   PTR used_by_bfd;..        {* If this is a constructor section then here is a list of the.           relocations created to relocate items within it. *}..   struct relent_chain *constructor_chain;..        {* The BFD which owns the section. *}..   bfd *owner;..   boolean reloc_done;.	 {* A symbol which points at this section only *}.   struct symbol_cache_entry *symbol;  .   struct symbol_cache_entry **symbol_ptr_ptr;.   struct bfd_seclet_struct *seclets_head;.   struct bfd_seclet_struct *seclets_tail;.} asection ;...#define BFD_ABS_SECTION_NAME "*ABS*".#define BFD_UND_SECTION_NAME "*UND*".#define BFD_COM_SECTION_NAME "*COM*"..    {* the absolute section *}. extern   asection bfd_abs_section;.    {* Pointer to the undefined section *}. extern   asection bfd_und_section;.    {* Pointer to the common section *}. extern asection bfd_com_section;.. extern struct symbol_cache_entry *bfd_abs_symbol;. extern struct symbol_cache_entry *bfd_com_symbol;. extern struct symbol_cache_entry *bfd_und_symbol;.#define bfd_get_section_size_before_reloc(section) \.     (section->reloc_done ? (abort(),1): (section)->_raw_size).#define bfd_get_section_size_after_reloc(section) \.     ((section->reloc_done) ? (section)->_cooked_size: (abort(),1))*//* These symbols are global, not specific to any BFD.  Therefore, anything   that tries to change them is broken, and should be repaired.  */static CONST asymbol global_syms[] = {  /* bfd, name, value, attr, section [, udata] */  { 0, BFD_COM_SECTION_NAME, 0, BSF_SECTION_SYM, &bfd_com_section },  { 0, BFD_UND_SECTION_NAME, 0, BSF_SECTION_SYM, &bfd_und_section },  { 0, BFD_ABS_SECTION_NAME, 0, BSF_SECTION_SYM, &bfd_abs_section },};#define STD_SECTION(SEC,SYM,NAME, IDX)	\  asymbol *SYM = (asymbol *) &global_syms[IDX]; \  asection SEC = { NAME, 0, 0, 0, 0, (boolean) 0, 0, 0, 0, &SEC,\		    0, 0, 0, 0, 0, 0, 0, 0,  0, 0, 0, 0, 0, 0, 0, 0, (boolean) 0, \		     (asymbol *) &global_syms[IDX], &SYM, }STD_SECTION (bfd_com_section, bfd_com_symbol, BFD_COM_SECTION_NAME, 0);STD_SECTION (bfd_und_section, bfd_und_symbol, BFD_UND_SECTION_NAME, 1);STD_SECTION (bfd_abs_section, bfd_abs_symbol, BFD_ABS_SECTION_NAME, 2);#undef STD_SECTION/*DOCDDINODEsection prototypes,  , typedef asection, SectionsSUBSECTION	section prototypesThese are the functions exported by the section handling part of<<libbfd>.*//*FUNCTION 	bfd_get_section_by_nameSYNOPSIS	asection *bfd_get_section_by_name(bfd *abfd, CONST char *name);DESCRIPTION	Runs through the provided @var{abfd} and returns the	<<asection>> who's name matches that provided, otherwise NULL.	@xref{Sections}, for more information.*/