Subversion Repositories openrisc_2011-10-31

@section Sections

The raw data contained within a BFD is maintained through the

section abstraction.  A single BFD may have any number of

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 @code{section.c}.

@menu

* Section Input::

* Section Output::

* typedef asection::

* section prototypes::

@end menu

@node Section Input, Section Output, Sections, Sections

@subsection 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, @code{a.out} would contain at least

three sections, called @code{.text}, @code{.data} and @code{.bss}.

Names need not be unique; for example a COFF file may have several

sections named @code{.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

@code{bfd_make_section}) to the sections attached to an already open

BFD. For example, the linker creates an extra section

@code{COMMON} for each input file's BFD to hold information about

common storage.

The raw data is not necessarily read in when

the section descriptor is created. Some targets may leave the

data in place until a @code{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.

@node Section Output, typedef asection, Section Input, Sections

@subsection 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 @code{bfd_set_section_contents}.

Any program that creates or combines sections (e.g., the assembler

and linker) must use the @code{asection} fields @code{output_section} and

@code{output_offset} to indicate the file sections to which each

section must be written.  (If the section is being created from

scratch, @code{output_section} should probably point to the section

itself and @code{output_offset} should probably be zero.)

The data to be written comes from input sections attached

(via @code{output_section} pointers) 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 (i.e., at vma

0x100) and "B" at offset 0x20 (i.e., at vma 0x120) the @code{asection}

structures would look like:

@example

   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  --------|

@end example

@subsection Link orders

The data within a section is stored in a @dfn{link_order}.

These are much like the fixups in @code{gas}.  The link_order

abstraction allows a section to grow and shrink within itself.

A link_order knows how big it is, and which is the next

link_order and where the raw data for it is; it also points to

a list of relocations which apply to it.

The link_order 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 link_order by link_order basis.

@node typedef asection, section prototypes, Section Output, Sections

@subsection typedef asection

Here is the section structure:

@example

typedef struct bfd_section

@{

  /* 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;

  /* A unique sequence number.  */

  int id;

  /* Which section in the bfd; 0..n-1 as sections are created in a bfd.  */

  int index;

  /* The next section in the list belonging to the BFD, or NULL.  */

  struct bfd_section *next;

  /* The previous section in the list belonging to the BFD, or NULL.  */

  struct bfd_section *prev;

  /* The field flags contains attributes of the section. Some

     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 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 is clear for a .bss section.  */

#define SEC_LOAD       0x002

  /* The section contains data still to be relocated, so there is

     some relocation information too.  */

#define SEC_RELOC      0x004

  /* A signal to the OS that the section contains read only data.  */

#define SEC_READONLY   0x008

  /* The section contains code only.  */

#define SEC_CODE       0x010

  /* The section contains data only.  */

#define SEC_DATA       0x020

  /* The section will reside in ROM.  */

#define SEC_ROM        0x040

  /* The section contains constructor information. This section

     type is used by the linker to create lists of constructors and

     destructors used by @code{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 (e.g., @code{__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 @code{__CTOR_LIST__} and relocate the data

     contained within - exactly the operations it would peform on

     standard data.  */

#define SEC_CONSTRUCTOR 0x080

  /* The section has contents - a data section could be

     @code{SEC_ALLOC} | @code{SEC_HAS_CONTENTS}; a debug section could be

     @code{SEC_HAS_CONTENTS}  */

#define SEC_HAS_CONTENTS 0x100

  /* An instruction to the linker to not output the section

     even if it has information which would normally be written.  */

#define SEC_NEVER_LOAD 0x200

  /* The section contains thread local data.  */

#define SEC_THREAD_LOCAL 0x400

  /* The section has GOT references.  This flag is only for the

     linker, and is currently only used by the elf32-hppa back end.

     It will be set if global offset table references were detected

     in this section, which indicate to the linker that the section

     contains PIC code, and must be handled specially when doing a

     static link.  */

#define SEC_HAS_GOT_REF 0x800

  /* The section contains common symbols (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_ptr), but ECOFF has two.  */

#define SEC_IS_COMMON 0x1000

  /* 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 0x2000

  /* The contents of this section are held in memory pointed to

     by the contents field.  This is checked by bfd_get_section_contents,

     and the data is retrieved from memory if appropriate.  */

#define SEC_IN_MEMORY 0x4000

  /* The contents of this section are to be excluded by the

     linker for executable and shared objects unless those

     objects are to be further relocated.  */

#define SEC_EXCLUDE 0x8000

  /* The contents of this section are to be sorted based on the sum of

     the symbol and addend values specified by the associated relocation

     entries.  Entries without associated relocation entries will be

     appended to the end of the section in an unspecified order.  */

#define SEC_SORT_ENTRIES 0x10000

  /* When linking, duplicate sections of the same name should be

     discarded, rather than being combined into a single section as

     is usually done.  This is similar to how common symbols are

     handled.  See SEC_LINK_DUPLICATES below.  */

#define SEC_LINK_ONCE 0x20000

  /* If SEC_LINK_ONCE is set, this bitfield describes how the linker

     should handle duplicate sections.  */

#define SEC_LINK_DUPLICATES 0xc0000

  /* This value for SEC_LINK_DUPLICATES means that duplicate

     sections with the same name should simply be discarded.  */

#define SEC_LINK_DUPLICATES_DISCARD 0x0

  /* This value for SEC_LINK_DUPLICATES means that the linker

     should warn if there are any duplicate sections, although

     it should still only link one copy.  */

#define SEC_LINK_DUPLICATES_ONE_ONLY 0x40000

  /* This value for SEC_LINK_DUPLICATES means that the linker

     should warn if any duplicate sections are a different size.  */

#define SEC_LINK_DUPLICATES_SAME_SIZE 0x80000

  /* This value for SEC_LINK_DUPLICATES means that the linker

     should warn if any duplicate sections contain different

     contents.  */

#define SEC_LINK_DUPLICATES_SAME_CONTENTS \

  (SEC_LINK_DUPLICATES_ONE_ONLY | SEC_LINK_DUPLICATES_SAME_SIZE)

  /* This section was created by the linker as part of dynamic

     relocation or other arcane processing.  It is skipped when

     going through the first-pass output, trusting that someone

     else up the line will take care of it later.  */

#define SEC_LINKER_CREATED 0x100000

  /* This section should not be subject to garbage collection.

     Also set to inform the linker that this section should not be

     listed in the link map as discarded.  */

#define SEC_KEEP 0x200000

  /* This section contains "short" data, and should be placed

     "near" the GP.  */

#define SEC_SMALL_DATA 0x400000

  /* Attempt to merge identical entities in the section.

     Entity size is given in the entsize field.  */

#define SEC_MERGE 0x800000

  /* If given with SEC_MERGE, entities to merge are zero terminated

     strings where entsize specifies character size instead of fixed

     size entries.  */

#define SEC_STRINGS 0x1000000

  /* This section contains data about section groups.  */

#define SEC_GROUP 0x2000000

  /* The section is a COFF shared library section.  This flag is

     only for the linker.  If this type of section appears in

     the input file, the linker must copy it to the output file

     without changing the vma or size.  FIXME: Although this

     was originally intended to be general, it really is COFF

     specific (and the flag was renamed to indicate this).  It

     might be cleaner to have some more general mechanism to

     allow the back end to control what the linker does with

     sections.  */

#define SEC_COFF_SHARED_LIBRARY 0x4000000

  /* This section contains data which may be shared with other

     executables or shared objects. This is for COFF only.  */

#define SEC_COFF_SHARED 0x8000000

  /* When a section with this flag is being linked, then if the size of

     the input section is less than a page, it should not cross a page

     boundary.  If the size of the input section is one page or more,

     it should be aligned on a page boundary.  This is for TI

     TMS320C54X only.  */

#define SEC_TIC54X_BLOCK 0x10000000

  /* Conditionally link this section; do not link if there are no

     references found to any symbol in the section.  This is for TI

     TMS320C54X only.  */

#define SEC_TIC54X_CLINK 0x20000000

  /*  End of section flags.  */

  /* Some internal packed boolean fields.  */

  /* See the vma field.  */

  unsigned int user_set_vma : 1;

  /* A mark flag used by some of the linker backends.  */

  unsigned int linker_mark : 1;

  /* Another mark flag used by some of the linker backends.  Set for

     output sections that have an input section.  */

  unsigned int linker_has_input : 1;

  /* Mark flag used by some linker backends for garbage collection.  */

  unsigned int gc_mark : 1;

  /* The following flags are used by the ELF linker. */

  /* Mark sections which have been allocated to segments.  */

  unsigned int segment_mark : 1;

  /* Type of sec_info information.  */

  unsigned int sec_info_type:3;

#define ELF_INFO_TYPE_NONE      0

#define ELF_INFO_TYPE_STABS     1

#define ELF_INFO_TYPE_MERGE     2

#define ELF_INFO_TYPE_EH_FRAME  3

#define ELF_INFO_TYPE_JUST_SYMS 4

  /* Nonzero if this section uses RELA relocations, rather than REL.  */

  unsigned int use_rela_p:1;

  /* Bits used by various backends.  The generic code doesn't touch

     these fields.  */

  /* Nonzero if this section has TLS related relocations.  */

  unsigned int has_tls_reloc:1;

  /* Nonzero if this section has a gp reloc.  */

  unsigned int has_gp_reloc:1;

  /* Nonzero if this section needs the relax finalize pass.  */

  unsigned int need_finalize_relax:1;

  /* Whether relocations have been processed.  */

  unsigned int reloc_done : 1;

  /* End of internal packed boolean fields.  */

  /*  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 @code{a.out}, where

      the default address for @code{.data} is dependent on the specific

      target and various flags).  */

  bfd_vma 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 octets, as it will be output.

     Contains a value even if the section has no contents (e.g., the

     size of @code{.bss}).  */

  bfd_size_type size;

  /* For input sections, the original size on disk of the section, in

     octets.  This field should be set for any section whose size is

     changed by linker relaxation.  It is required for sections where

     the linker relaxation scheme doesn't cache altered section and

     reloc contents (stabs, eh_frame, SEC_MERGE, some coff relaxing

     targets), and thus the original size needs to be kept to read the

     section multiple times.  For output sections, rawsize holds the

     section size calculated on a previous linker relaxation pass.  */

  bfd_size_type rawsize;

  /* If this section is going to be output, then this value is the

     offset in *bytes* into the output section of the first byte in the

     input section (byte ==> smallest addressable unit on the

     target).  In most cases, if this was going to start at the

     100th octet (8-bit quantity) in the output section, this value

     would be 100.  However, if the target byte size is 16 bits

     (bfd_octets_per_byte is "2"), this value would be 50.  */

  bfd_vma output_offset;

  /* The output section through which to map on output.  */

  struct bfd_section *output_section;

  /* The alignment requirement of the section, as an exponent of 2 -

     e.g., 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.  */

  void *userdata;

  /* If the SEC_IN_MEMORY flag is set, this points to the actual

     contents.  */

  unsigned char *contents;

  /* Attached line number information.  */

  alent *lineno;

  /* Number of line number records.  */

  unsigned int lineno_count;

  /* Entity size for merging purposes.  */

  unsigned int entsize;

  /* Points to the kept section if this section is a link-once section,

     and is discarded.  */

  struct bfd_section *kept_section;

  /* 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;

  void *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;

  /* A symbol which points at this section only.  */

  struct bfd_symbol *symbol;

  struct bfd_symbol **symbol_ptr_ptr;

  /* Early in the link process, map_head and map_tail are used to build

     a list of input sections attached to an output section.  Later,

     output sections use these fields for a list of bfd_link_order

     structs.  */

  union @{

    struct bfd_link_order *link_order;

    struct bfd_section *s;

  @} map_head, map_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.  New code should use the section_ptr macros rather

   than referring directly to the const sections.  The const sections

   may eventually vanish.  */

#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;

#define bfd_abs_section_ptr ((asection *) &bfd_abs_section)

#define bfd_is_abs_section(sec) ((sec) == bfd_abs_section_ptr)

/* Pointer to the undefined section.  */

extern asection bfd_und_section;

#define bfd_und_section_ptr ((asection *) &bfd_und_section)

#define bfd_is_und_section(sec) ((sec) == bfd_und_section_ptr)

/* Pointer to the common section.  */

extern asection bfd_com_section;

#define bfd_com_section_ptr ((asection *) &bfd_com_section)

/* Pointer to the indirect section.  */

extern asection bfd_ind_section;

#define bfd_ind_section_ptr ((asection *) &bfd_ind_section)

#define bfd_is_ind_section(sec) ((sec) == bfd_ind_section_ptr)

#define bfd_is_const_section(SEC)              \

 (   ((SEC) == bfd_abs_section_ptr)            \

  || ((SEC) == bfd_und_section_ptr)            \

  || ((SEC) == bfd_com_section_ptr)            \

  || ((SEC) == bfd_ind_section_ptr))

/* Macros to handle insertion and deletion of a bfd's sections.  These

   only handle the list pointers, ie. do not adjust section_count,

   target_index etc.  */

#define bfd_section_list_remove(ABFD, S) \

  do                                                   \

    @{                                                  \

      asection *_s = S;                                \

      asection *_next = _s->next;                      \

      asection *_prev = _s->prev;                      \

      if (_prev)                                       \

        _prev->next = _next;                           \

      else                                             \

        (ABFD)->sections = _next;                      \

      if (_next)                                       \

        _next->prev = _prev;                           \

      else                                             \

        (ABFD)->section_last = _prev;                  \

    @}                                                  \

  while (0)

#define bfd_section_list_append(ABFD, S) \

  do                                                   \

    @{                                                  \

      asection *_s = S;                                \

      bfd *_abfd = ABFD;                               \

      _s->next = NULL;                                 \

      if (_abfd->section_last)                         \

        @{                                              \

          _s->prev = _abfd->section_last;              \

          _abfd->section_last->next = _s;              \

        @}                                              \

      else                                             \

        @{                                              \

          _s->prev = NULL;                             \

          _abfd->sections = _s;                        \

        @}                                              \

      _abfd->section_last = _s;                        \

    @}                                                  \

  while (0)

#define bfd_section_list_prepend(ABFD, S) \

  do                                                   \

    @{                                                  \

      asection *_s = S;                                \

      bfd *_abfd = ABFD;                               \

      _s->prev = NULL;                                 \

      if (_abfd->sections)                             \

        @{                                              \

          _s->next = _abfd->sections;                  \

          _abfd->sections->prev = _s;                  \

        @}                                              \

      else                                             \

        @{                                              \

          _s->next = NULL;                             \

          _abfd->section_last = _s;                    \

        @}                                              \

      _abfd->sections = _s;                            \

    @}                                                  \

  while (0)

#define bfd_section_list_insert_after(ABFD, A, S) \

  do                                                   \

    @{                                                  \

      asection *_a = A;                                \

      asection *_s = S;                                \

      asection *_next = _a->next;                      \

      _s->next = _next;                                \

      _s->prev = _a;                                   \

      _a->next = _s;                                   \

      if (_next)                                       \

        _next->prev = _s;                              \

      else                                             \

        (ABFD)->section_last = _s;                     \

    @}                                                  \

  while (0)

#define bfd_section_list_insert_before(ABFD, B, S) \

  do                                                   \

    @{                                                  \

      asection *_b = B;                                \

      asection *_s = S;                                \

      asection *_prev = _b->prev;                      \

      _s->prev = _prev;                                \

      _s->next = _b;                                   \

      _b->prev = _s;                                   \

      if (_prev)                                       \

        _prev->next = _s;                              \

      else                                             \

        (ABFD)->sections = _s;                         \

    @}                                                  \

  while (0)

#define bfd_section_removed_from_list(ABFD, S) \

  ((S)->next == NULL ? (ABFD)->section_last != (S) : (S)->next->prev != (S))

#define BFD_FAKE_SECTION(SEC, FLAGS, SYM, NAME, IDX)                   \

  /* name, id,  index, next, prev, flags, user_set_vma,            */  \

  @{ NAME,  IDX, 0,     NULL, NULL, FLAGS, 0,                           \

                                                                       \

  /* linker_mark, linker_has_input, gc_mark,                       */  \

     0,           0,                1,                                 \

                                                                       \

  /* segment_mark, sec_info_type, use_rela_p, has_tls_reloc,       */  \

     0,            0,             0,          0,                       \

                                                                       \

  /* has_gp_reloc, need_finalize_relax, reloc_done,                */  \

     0,            0,                   0,                             \

                                                                       \

  /* vma, lma, size, rawsize                                       */  \

     0,   0,   0,    0,                                                \

                                                                       \

  /* output_offset, output_section,              alignment_power,  */  \

     0,             (struct bfd_section *) &SEC, 0,                    \

                                                                       \

  /* relocation, orelocation, reloc_count, filepos, rel_filepos,   */  \

     NULL,       NULL,        0,           0,       0,                 \

                                                                       \

  /* line_filepos, userdata, contents, lineno, lineno_count,       */  \

     0,            NULL,     NULL,     NULL,   0,                      \

                                                                       \

  /* entsize, kept_section, moving_line_filepos,                    */ \

     0,       NULL,          0,                                        \

                                                                       \

  /* target_index, used_by_bfd, constructor_chain, owner,          */  \

     0,            NULL,        NULL,              NULL,               \

                                                                       \

  /* symbol,                    symbol_ptr_ptr,                    */  \

     (struct bfd_symbol *) SYM, &SEC.symbol,                           \

                                                                       \

  /* map_head, map_tail                                            */  \

     @{ NULL @}, @{ NULL @}                                                \

    @}

@end example

@node section prototypes,  , typedef asection, Sections

@subsection Section prototypes

These are the functions exported by the section handling part of BFD.

@findex bfd_section_list_clear

@subsubsection @code{bfd_section_list_clear}

@strong{Synopsis}

@example

void bfd_section_list_clear (bfd *);

@end example

@strong{Description}@*

Clears the section list, and also resets the section count and

hash table entries.

@findex bfd_get_section_by_name

@subsubsection @code{bfd_get_section_by_name}

@strong{Synopsis}

@example

asection *bfd_get_section_by_name (bfd *abfd, const char *name);

@end example

@strong{Description}@*

Run through @var{abfd} and return the one of the

@code{asection}s whose name matches @var{name}, otherwise @code{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 @code{bfd_map_over_sections} and

@code{strcmp} on the name (or better yet, base it on the section flags

or something else) for each section.

@findex bfd_get_section_by_name_if

@subsubsection @code{bfd_get_section_by_name_if}

@strong{Synopsis}

@example

asection *bfd_get_section_by_name_if

   (bfd *abfd,

    const char *name,

    bfd_boolean (*func) (bfd *abfd, asection *sect, void *obj),

    void *obj);

@end example

@strong{Description}@*

Call the provided function @var{func} for each section

attached to the BFD @var{abfd} whose name matches @var{name},

passing @var{obj} as an argument. The function will be called

as if by

@example

       func (abfd, the_section, obj);

@end example

It returns the first section for which @var{func} returns true,

otherwise @code{NULL}.

@findex bfd_get_unique_section_name

@subsubsection @code{bfd_get_unique_section_name}

@strong{Synopsis}

@example

char *bfd_get_unique_section_name

   (bfd *abfd, const char *templat, int *count);

@end example

@strong{Description}@*

Invent a section name that is unique in @var{abfd} by tacking

a dot and a digit suffix onto the original @var{templat}.  If

@var{count} is non-NULL, then it specifies the first number

tried as a suffix to generate a unique name.  The value

pointed to by @var{count} will be incremented in this case.

@findex bfd_make_section_old_way

@subsubsection @code{bfd_make_section_old_way}

@strong{Synopsis}

@example

asection *bfd_make_section_old_way (bfd *abfd, const char *name);

@end example

@strong{Description}@*

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 it was rewritten....

Possible errors are:

@itemize @bullet

@item

@code{bfd_error_invalid_operation} -

If output has already started for this BFD.

@item

@code{bfd_error_no_memory} -

If memory allocation fails.

@end itemize

@findex bfd_make_section_anyway_with_flags

@subsubsection @code{bfd_make_section_anyway_with_flags}

@strong{Synopsis}

@example

asection *bfd_make_section_anyway_with_flags

   (bfd *abfd, const char *name, flagword flags);

@end example

@strong{Description}@*

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.  Also set the attributes of the

new section to the value @var{flags}.

Return @code{NULL} and set @code{bfd_error} on error; possible errors are:

@itemize @bullet

@item

@code{bfd_error_invalid_operation} - If output has already started for @var{abfd}.

@item

@code{bfd_error_no_memory} - If memory allocation fails.

@end itemize

@findex bfd_make_section_anyway

@subsubsection @code{bfd_make_section_anyway}

@strong{Synopsis}

@example

asection *bfd_make_section_anyway (bfd *abfd, const char *name);

@end example

@strong{Description}@*

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.

Return @code{NULL} and set @code{bfd_error} on error; possible errors are:

@itemize @bullet

@item

@code{bfd_error_invalid_operation} - If output has already started for @var{abfd}.

@item

@code{bfd_error_no_memory} - If memory allocation fails.

@end itemize

@findex bfd_make_section_with_flags

@subsubsection @code{bfd_make_section_with_flags}

@strong{Synopsis}

@example

asection *bfd_make_section_with_flags

   (bfd *, const char *name, flagword flags);

@end example

@strong{Description}@*

Like @code{bfd_make_section_anyway}, but return @code{NULL} (without calling

bfd_set_error ()) without changing the section chain if there is already a

section named @var{name}.  Also set the attributes of the new section to

the value @var{flags}.  If there is an error, return @code{NULL} and set

@code{bfd_error}.

@findex bfd_make_section

@subsubsection @code{bfd_make_section}

@strong{Synopsis}

@example

asection *bfd_make_section (bfd *, const char *name);

@end example

@strong{Description}@*

Like @code{bfd_make_section_anyway}, but return @code{NULL} (without calling

bfd_set_error ()) without changing the section chain if there is already a

section named @var{name}.  If there is an error, return @code{NULL} and set

@code{bfd_error}.

@findex bfd_set_section_flags

@subsubsection @code{bfd_set_section_flags}

@strong{Synopsis}

@example

bfd_boolean bfd_set_section_flags

   (bfd *abfd, asection *sec, flagword flags);

@end example

@strong{Description}@*

Set the attributes of the section @var{sec} in the BFD

@var{abfd} to the value @var{flags}. Return @code{TRUE} on success,

@code{FALSE} on error. Possible error returns are:

@itemize @bullet

@item

@code{bfd_error_invalid_operation} -

The section cannot have one or more of the attributes

requested. For example, a .bss section in @code{a.out} may not

have the @code{SEC_HAS_CONTENTS} field set.

@end itemize

@findex bfd_map_over_sections

@subsubsection @code{bfd_map_over_sections}

@strong{Synopsis}

@example

void bfd_map_over_sections

   (bfd *abfd,

    void (*func) (bfd *abfd, asection *sect, void *obj),

    void *obj);

@end example

@strong{Description}@*

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

@example

       func (abfd, the_section, obj);

@end example

This is the preferred method for iterating over sections; an

alternative would be to use a loop:

@example

          section *p;

          for (p = abfd->sections; p != NULL; p = p->next)

             func (abfd, p, ...)

@end example

@findex bfd_sections_find_if

@subsubsection @code{bfd_sections_find_if}

@strong{Synopsis}

@example

asection *bfd_sections_find_if

   (bfd *abfd,

    bfd_boolean (*operation) (bfd *abfd, asection *sect, void *obj),

    void *obj);

@end example

@strong{Description}@*

Call the provided function @var{operation} for each section

attached to the BFD @var{abfd}, passing @var{obj} as an

argument. The function will be called as if by

@example

       operation (abfd, the_section, obj);

@end example

It returns the first section for which @var{operation} returns true.

@findex bfd_set_section_size

@subsubsection @code{bfd_set_section_size}

@strong{Synopsis}

@example

bfd_boolean bfd_set_section_size

   (bfd *abfd, asection *sec, bfd_size_type val);

@end example

@strong{Description}@*

Set @var{sec} to the size @var{val}. If the operation is

ok, then @code{TRUE} is returned, else @code{FALSE}.

Possible error returns:

@itemize @bullet

@item

@code{bfd_error_invalid_operation} -

Writing has started to the BFD, so setting the size is invalid.

@end itemize

@findex bfd_set_section_contents

@subsubsection @code{bfd_set_section_contents}

@strong{Synopsis}

@example

bfd_boolean bfd_set_section_contents

   (bfd *abfd, asection *section, const void *data,

    file_ptr offset, bfd_size_type count);

@end example

@strong{Description}@*

Sets the contents of the section @var{section} in BFD

@var{abfd} to the data starting in memory at @var{data}. The

data is written to the output section starting at offset

@var{offset} for @var{count} octets.

Normally @code{TRUE} is returned, else @code{FALSE}. Possible error

returns are:

@itemize @bullet

@item

@code{bfd_error_no_contents} -

The output section does not have the @code{SEC_HAS_CONTENTS}

attribute, so nothing can be written to it.

@item

and some more too

@end itemize

This routine is front end to the back end function

@code{_bfd_set_section_contents}.

@findex bfd_get_section_contents

@subsubsection @code{bfd_get_section_contents}

@strong{Synopsis}

@example

bfd_boolean bfd_get_section_contents

   (bfd *abfd, asection *section, void *location, file_ptr offset,

    bfd_size_type count);

@end example

@strong{Description}@*

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.

If the contents of a constructor with the @code{SEC_CONSTRUCTOR}

flag set are requested or if the section does not have the

@code{SEC_HAS_CONTENTS} flag set, then the @var{location} is filled

with zeroes. If no errors occur, @code{TRUE} is returned, else

@code{FALSE}.

@findex bfd_malloc_and_get_section

@subsubsection @code{bfd_malloc_and_get_section}

@strong{Synopsis}

@example

bfd_boolean bfd_malloc_and_get_section

   (bfd *abfd, asection *section, bfd_byte **buf);

@end example

@strong{Description}@*

Read all data from @var{section} in BFD @var{abfd}

into a buffer, *@var{buf}, malloc'd by this function.