/* Object file "section" support for the BFD library.
- Copyright (C) 1990-1991 Free Software Foundation, Inc.
+ Copyright (C) 1990, 1991, 1992, 1993 Free Software Foundation, Inc.
Written by Cygnus Support.
This file is part of BFD, the Binary File Descriptor library.
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,
+ sections. It keeps hold of them by pointing to the first;
each one points to the next in the list.
+ Sections are supported in BFD in <<section.c>>.
+
@menu
@* Section Input::
@* Section Output::
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
+ 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
+ Names need not be unique; for example a COFF file may have several
+ sections named <<.data>>.
+
+ 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
+ <<bfd_make_section>>) to the sections attached to an already open
+ BFD. For example, the linker creates an extra 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 raw data is not necessarily read in when
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
+ 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
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
+ 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
+ and linker) must use the <<asection>> 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.)
+ itself and <<output_offset>> should probably be zero.)
- The data to be written comes from input sections attached to
+ The data to be written comes from input sections attached
+ (via <<output_section>> pointers) to
the output sections. The output section structure can be
- considered a filter for the input section, the output section
+ 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:
+ containing two subsections, "A" at offset 0x0 (i.e., at vma
+ 0x100) and "B" at offset 0x20 (i.e., at vma 0x120) the <<asection>>
+ structures would look like:
| section name "A"
| output_offset 0x00
SUBSECTION
- Seglets
+ Seclets
- 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.
+ The data within a section is stored in a <<seclet>>. These
+ are much like the fixups in <<gas>>. The seclet abstraction
+ allows 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
+ A seclet knows how big it is, and which is the next seclet and
+ where the raw data for it is; it 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
+ The seclet is used by the linker to perform relaxing on final
+ code. The compiler 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.
+ a seclet by seclet basis.
*/
SUBSECTION
typedef asection
- The shape of a section struct:
+ Here is the section structure:
CODE_FRAGMENT
.
.typedef struct sec
.{
-. {* The name of the section, the name isn't a copy, the pointer is
+. {* 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 *}
+. {* Which section is it; 0..nth. *}
.
. int index;
.
.
. struct sec *next;
.
-. {* The field flags contains attributes of the section. Some of
+. {* The field flags contains attributes of the section. Some
. flags are read in from the object file, and some are
. synthesized from other information. *}
.
.
.#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
+. {* Tells the OS to allocate space for this section when loading.
+. This is 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 *}
-.
+. This is 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. *}
.
+. {* The section contains data still to be relocated, so there is
+. some relocation information too. *}
.#define SEC_RELOC 0x004
.
-. {* Obsolete ? *}
-.
+.#if 0 {* Obsolete ? *}
.#define SEC_BALIGN 0x008
+.#endif
.
. {* 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
+.#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
+. section for the type of name (e.g., <<__CTOR_LIST__>>), attaches
+. the symbol to it, and builds a relocation. To build the lists
+. of constructors, all the linker has to do is catenate all the
+. sections called <<__CTOR_LIST__>> and relocate 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 . *}
-.
-.
+. end of the text, data, or bss section(?). *}
.#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
+. {* The section has contents - a data 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. *}
-.
+. {* An instruction to the linker to not output the section
+. even if it has information which would normally be written. *}
.#define SEC_NEVER_LOAD 0x400
.
+. {* The section is a shared library section. The linker must leave
+. these completely alone, as the vma and size are used when
+. the executable is loaded. *}
+.#define SEC_SHARED_LIBRARY 0x800
+.
+. {* The section is a common section (symbols may be defined
+. multiple times, the value of a symbol is the amount of
+. space it requires, and the largest symbol value is the one
+. used). Most targets have exactly one of these (which we
+. translate to bfd_com_section), but ECOFF has two. *}
+.#define SEC_IS_COMMON 0x8000
+.
+. {* The section contains only debugging information. For
+. example, this is set for ELF .debug and .stab sections.
+. strip tests this flag to see if a section can be
+. discarded. *}
+.#define SEC_DEBUGGING 0x10000
+.
+. {* End of section flags. *}
+.
+. {* The virtual memory address of the section - where it will be
+. at run time. The symbols are relocated against this. The
+. user_set_vma flag is maintained by bfd; if it's not set, the
+. backend can assign addresses (for example, in <<a.out>>, where
+. the default address for <<.data>> is dependent on the specific
+. target and various flags). *}
.
-.
. bfd_vma vma;
. boolean user_set_vma;
.
+. {* The load address of the section - where it would be in a
+. rom image; really only used for writing section header
+. information. *}
+.
+. bfd_vma lma;
+.
. {* The size of the section in bytes, as it will be output.
-. contains a value even if the section has no contents (eg, the
+. contains a value even if the section has no contents (e.g., 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
+. {* The original size on disk of the section, in bytes. Normally this
. value is the same as the size, but if some relaxing has
. been done, then this value will be bigger. *}
.
.
. {* 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
+. section. E.g., if this was going to start at the 100th byte in
. the output section, this value would be 100. *}
.
. bfd_vma output_offset;
.
. struct sec *output_section;
.
-. {* The alignment requirement of the section, as an exponent - eg
-. 3 aligns to 2^3 (or 8) *}
+. {* The alignment requirement of the section, as an exponent of 2 -
+. e.g., 3 aligns to 2^3 (or 8). *}
.
. unsigned int alignment_power;
.
. unsigned reloc_count;
.
. {* Information below is back end specific - and not always used
-. or updated
+. or updated. *}
.
-. File position of section data *}
+. {* File position of section data *}
.
. file_ptr filepos;
.
.
. file_ptr moving_line_filepos;
.
-. {* what the section number is in the target world *}
+. {* What the section number is in the target world *}
.
. int target_index;
.
. {* 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;
+.
+. struct bfd_seclet *seclets_head;
+. struct bfd_seclet *seclets_tail;
.} asection ;
.
.
+. {* These sections are global, and are managed by BFD. The application
+. and target back end are not permitted to change the values in
+. these sections. *}
.#define BFD_ABS_SECTION_NAME "*ABS*"
.#define BFD_UND_SECTION_NAME "*UND*"
.#define BFD_COM_SECTION_NAME "*COM*"
+.#define BFD_IND_SECTION_NAME "*IND*"
.
. {* the absolute section *}
-. extern asection bfd_abs_section;
+.extern asection bfd_abs_section;
. {* Pointer to the undefined section *}
-. extern asection bfd_und_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;
+.extern asection bfd_com_section;
+. {* Pointer to the indirect section *}
+.extern asection bfd_ind_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;
+.extern struct symbol_cache_entry *bfd_ind_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) \
/* 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] */
+ /* the_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 },
+ { 0, BFD_IND_SECTION_NAME, 0, BSF_SECTION_SYM, &bfd_ind_section },
};
-#define STD_SECTION(SEC,SYM,NAME, IDX) \
+#define STD_SECTION(SEC, FLAGS, SYM, NAME, IDX) \
asymbol *SYM = (asymbol *) &global_syms[IDX]; \
- asection SEC = { NAME, 0, 0, 0, 0, (boolean) 0, 0, 0, 0, &SEC,\
+ asection SEC = { NAME, 0, 0, FLAGS, 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);
+STD_SECTION (bfd_com_section, SEC_IS_COMMON, bfd_com_symbol, BFD_COM_SECTION_NAME, 0);
+STD_SECTION (bfd_und_section, 0, bfd_und_symbol, BFD_UND_SECTION_NAME, 1);
+STD_SECTION (bfd_abs_section, 0, bfd_abs_symbol, BFD_ABS_SECTION_NAME, 2);
+STD_SECTION (bfd_ind_section, 0, bfd_ind_symbol, BFD_IND_SECTION_NAME, 3);
#undef STD_SECTION
/*
section prototypes
These are the functions exported by the section handling part of
-<<libbfd>.
+<<libbfd>>.
*/
/*
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.
+ Run through the provided @var{abfd} and return the one of the
+ <<asection>>s whose name matches @var{name}, otherwise NULL.
@xref{Sections}, for more information.
+ This should only be used in special cases; the normal way to process
+ all sections of a given name is to use bfd_map_over_sections and
+ strcmp on the name (or better yet, base it on the section flags
+ or something else) for each section.
*/
asection *
bfd_make_section_old_way
SYNOPSIS
- asection *bfd_make_section_old_way(bfd *, CONST char *name);
+ asection *bfd_make_section_old_way(bfd *abfd, CONST char *name);
DESCRIPTION
- This function creates a new empty section called @var{name}
- and attaches it to the end of the chain of sections for the
- BFD supplied. An attempt to create a section with a name which
+ Create a new empty section called @var{name}
+ and attach it to the end of the chain of sections for the
+ BFD @var{abfd}. An attempt to create a section with a name which
is already in use, returns its pointer without changing the
section chain.
It has the funny name since this is the way it used to be
- before is was rewritten...
+ before it was rewritten....
Possible errors are:
o invalid_operation -
return sec;
}
-
/*
FUNCTION
- bfd_make_section
+ bfd_make_section_anyway
SYNOPSIS
- asection * bfd_make_section(bfd *, CONST char *name);
+ asection *bfd_make_section_anyway(bfd *abfd, CONST char *name);
DESCRIPTION
- This function creates a new empty section called @var{name}
- and attaches it to the end of the chain of sections for the
- BFD supplied. An attempt to create a section with a name which
- is already in use, returns NULL without changing the section
- chain.
+ Create a new empty section called @var{name} and attach it to the end of
+ the chain of sections for @var{abfd}. Create a new section even if there
+ is already a section with that name.
- Possible errors are:
- o invalid_operation - If output has already started for this BFD.
- o no_memory - If obstack alloc fails.
+ Returns NULL and sets bfd_error on error; possible errors are:
+ o invalid_operation - If output has already started for @var{abfd}.
+ o no_memory - If obstack alloc fails.
*/
-
-
sec_ptr
-DEFUN(bfd_make_section,(abfd, name),
- bfd *abfd AND
- CONST char * name)
+bfd_make_section_anyway (abfd, name)
+ bfd *abfd;
+ CONST char *name;
{
- asection *newsect;
- asection ** prev = &abfd->sections;
+ asection *newsect;
+ asection **prev = &abfd->sections;
asection * sect = abfd->sections;
-
- if (abfd->output_has_begun) {
- bfd_error = invalid_operation;
- return NULL;
- }
- if (strcmp(name, BFD_ABS_SECTION_NAME) == 0)
- {
- return &bfd_abs_section;
- }
- if (strcmp(name, BFD_COM_SECTION_NAME) == 0)
- {
- return &bfd_com_section;
- }
- if (strcmp(name, BFD_UND_SECTION_NAME) == 0)
- {
- return &bfd_und_section;
- }
-
+ if (abfd->output_has_begun)
+ {
+ bfd_error = invalid_operation;
+ return NULL;
+ }
+
while (sect) {
- if (!strcmp(sect->name, name)) return NULL;
prev = §->next;
sect = sect->next;
}
newsect->symbol->value = 0;
newsect->symbol->section = newsect;
newsect->symbol->flags = BSF_SECTION_SYM;
-
newsect->symbol_ptr_ptr = &newsect->symbol;
-
+
if (BFD_SEND (abfd, _new_section_hook, (abfd, newsect)) != true) {
free (newsect);
return NULL;
return newsect;
}
+/*
+FUNCTION
+ bfd_make_section
+
+SYNOPSIS
+ asection *bfd_make_section(bfd *, CONST char *name);
+
+DESCRIPTION
+ Like <<bfd_make_section_anyway>>, but return NULL (without setting
+ bfd_error) without changing the section chain if there is already a
+ section named @var{name}. If there is an error, return NULL and set
+ bfd_error.
+*/
+
+sec_ptr
+DEFUN(bfd_make_section,(abfd, name),
+ bfd *abfd AND
+ CONST char * name)
+{
+ asection * sect = abfd->sections;
+
+ if (strcmp(name, BFD_ABS_SECTION_NAME) == 0)
+ {
+ return &bfd_abs_section;
+ }
+ if (strcmp(name, BFD_COM_SECTION_NAME) == 0)
+ {
+ return &bfd_com_section;
+ }
+ if (strcmp(name, BFD_UND_SECTION_NAME) == 0)
+ {
+ return &bfd_und_section;
+ }
+
+ if (strcmp(name, BFD_IND_SECTION_NAME) == 0)
+ {
+ return &bfd_ind_section;
+ }
+
+ while (sect) {
+ if (!strcmp(sect->name, name)) return NULL;
+ sect = sect->next;
+ }
+
+ /* The name is not already used; go ahead and make a new section. */
+ return bfd_make_section_anyway (abfd, name);
+}
+
/*
FUNCTION
bfd_set_section_flags
SYNOPSIS
- boolean bfd_set_section_flags(bfd *, asection *, flagword);
+ boolean bfd_set_section_flags(bfd *abfd, asection *sec, flagword flags);
DESCRIPTION
- Attempts to set the attributes of the section named in the BFD
- supplied to the value. Returns true on success, false on
- error. Possible error returns are:
+ Set the attributes of the section @var{sec} in the BFD
+ @var{abfd} to the value @var{flags}. Returns <<true>> on success,
+ <<false>> on error. Possible error returns are:
o invalid operation -
The section cannot have one or more of the attributes
PTR obj);
DESCRIPTION
- Calls the provided function @var{func} for each section
+ Call the provided function @var{func} for each section
attached to the BFD @var{abfd}, passing @var{obj} as an
argument. The function will be called as if by
| func(abfd, the_section, obj);
- This is the prefered method for iterating over sections, an
+ This is the prefered method for iterating over sections; an
alternative would be to use a loop:
| section *p;
bfd_set_section_size
SYNOPSIS
- boolean bfd_set_section_size(bfd *, asection *, bfd_size_type val);
+ boolean bfd_set_section_size(bfd *abfd, asection *sec, bfd_size_type val);
DESCRIPTION
- Sets @var{section} to the size @var{val}. If the operation is
+ Set @var{sec} to the size @var{val}. If the operation is
ok, then <<true>> is returned, else <<false>>.
Possible error returns:
{
bfd_size_type sz;
- if (!(bfd_get_section_flags(abfd, section) & SEC_HAS_CONTENTS))
+ if (!bfd_get_section_flags(abfd, section) & SEC_HAS_CONTENTS)
{
bfd_error = no_contents;
return(false);
}
- if (offset < 0 || count < 0)
+ if (offset < 0)
{
bad_val:
bfd_error = bad_value;
|| offset + count > sz)
goto bad_val;
+ switch (abfd->direction)
+ {
+ case read_direction:
+ case no_direction:
+ bfd_error = invalid_operation;
+ return false;
+
+ case write_direction:
+ break;
+
+ case both_direction:
+ /* File is opened for update. `output_has_begun' some time ago when
+ the file was created. Do not recompute sections sizes or alignments
+ in _bfd_set_section_content. */
+ abfd->output_has_begun = true;
+ break;
+ }
+
if (BFD_SEND (abfd, _bfd_set_section_contents,
(abfd, section, location, offset, count)))
{
file_ptr offset, bfd_size_type count);
DESCRIPTION
- This function reads data from @var{section} in BFD @var{abfd}
+ Read data from @var{section} in BFD @var{abfd}
into memory starting at @var{location}. The data is read at an
offset of @var{offset} from the start of the input section,
and is read for @var{count} bytes.
return true;
}
- if (offset < 0 || count < 0)
+ if (offset < 0)
{
bad_val:
bfd_error = bad_value;
projects / deliverable / binutils-gdb.git / blobdiff