diff options
Diffstat (limited to 'bfd/section.c')
| -rw-r--r-- | bfd/section.c | 772 |
1 files changed, 430 insertions, 342 deletions
diff --git a/bfd/section.c b/bfd/section.c index 18baa11..ab3bb51 100644 --- a/bfd/section.c +++ b/bfd/section.c @@ -18,14 +18,16 @@ You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */ -/*doc* -@section Sections -Sections are supported in BFD in @code{section.c}. +/* +SECTION + Sections -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. + 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:: @@ -34,64 +36,73 @@ the list. * 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}. - -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 @code{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 @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}. - -The linker uses the fields @code{output_section} and -@code{output_offset} to create an output file. - -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. - -Eg 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 --------| - -*- +INODE + 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, <<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. + +INODE + 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 <<bfd_set_section_contents>>. + + The linker uses the fields <<output_section>> and + <<output_offset>> to create an output file. + + 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. + + Eg 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 --------| + */ @@ -100,241 +111,301 @@ subsections, "A" at offset 0x0 (ie at vma 0x100) and "B" at offset #include "sysdep.h" #include "libbfd.h" - -/*doc* -@node typedef asection, section prototypes, Section Output, Sections -@subsection typedef asection +/* +INODE + typedef asection, section prototypes, Section Output, Sections +SUBSECTION + typedef asection + +SUBSECTION + 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; +. +. {* 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 +. +. {* The base address of the section in the address space of the +. target. *} +. +. bfd_vma vma; +. +. {* The size of the section in bytes of the loaded section. This +. contains a value even if the section has no contents (eg, the +. size of <<.bss>>). *} +. +. bfd_size_type 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; +. +. {* Which section is it 0.nth *} +. +. int index; +. +. {* 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 *} +. +. unsigned 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; +. +.} asection ; */ -/*proto* -The shape of a section struct: - -*+++ - -$typedef struct sec { - -The name of the section, the name isn't a copy, the pointer is -the same as that passed to bfd_make_section. - -$ CONST char *name; - -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 these -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 @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 -(eg @code{__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 @code{__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 -@code{SEC_ALLOC} | @code{SEC_HAS_CONTENTS}, a debug section could be -@code{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 - - -The base address of the section in the address space of the target. - -$ bfd_vma vma; - -The size of the section in bytes of the loaded section. This contains -a value even if the section has no contents (eg, the size of @code{.bss}). - -$ bfd_size_type 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. +/* +INODE + section prototypes, , typedef asection, Sections -$ struct reloc_cache_entry **orelocation; +SUBSECTION + section prototypes -The number of relocation records in one of the above - -$ unsigned reloc_count; - -Which section is it 0..nth - -$ int index; - -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 +These are the functions exported by the section handling part of +<<libbfd>. +*/ -$ unsigned int lineno_count; +/* +FUNCTION + bfd_get_section_by_name -When a section is being output, this value changes as more -linenumbers are written out +SYNOPSIS + asection *bfd_get_section_by_name(bfd *abfd, CONST char *name); -$ file_ptr moving_line_filepos; +DESCRIPTION + Runs through the provided @var{abfd} and returns the + <<asection>> who's name matches that provided, otherwise NULL. + @xref{Sections}, for more information. -what the section number is in the target world +*/ -$ unsigned int target_index; +asection * +DEFUN(bfd_get_section_by_name,(abfd, name), + bfd *abfd AND + CONST char *name) +{ + asection *sect; -$ PTR used_by_bfd; + for (sect = abfd->sections; sect != NULL; sect = sect->next) + if (!strcmp (sect->name, name)) return sect; + return NULL; +} -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; +/* +FUNCTION + bfd_make_section_old_way -The BFD which owns the section. +SYNOPSIS + asection *bfd_make_section_old_way(bfd *, CONST char *name); -$ bfd *owner; +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 its pointer without changing the + section chain. -$} asection ; + It has the funny name since this is the way it used to be + before is was rewritten... -*--- + Possible errors are: + o invalid_operation + If output has already started for this BFD. + o no_memory + If obstack alloc fails. */ -/*doc* -@node section prototypes, , typedef asection, Sections -@subsection section prototypes -*/ -/*proto* bfd_get_section_by_name -Runs through the provided @var{abfd} and returns the @code{asection} -who's name matches that provided, otherwise NULL. @xref{Sections}, for more information. - -*; PROTO(asection *, bfd_get_section_by_name, - (bfd *abfd, CONST char *name)); -*/ asection * -DEFUN(bfd_get_section_by_name,(abfd, name), +DEFUN(bfd_make_section_old_way,(abfd, name), bfd *abfd AND - CONST char *name) + CONST char * name) { - asection *sect; - - for (sect = abfd->sections; sect != NULL; sect = sect->next) - if (!strcmp (sect->name, name)) return sect; - return NULL; + asection *sec = bfd_get_section_by_name(abfd, name); + if (sec == (asection *)NULL) + { + sec = bfd_make_section(abfd, name); + } + return sec; } -/*proto* bfd_make_section -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. +/* +FUNCTION + bfd_make_section -Possible errors are: -@table @code -@item invalid_operation -If output has already started for this BFD. -@item no_memory -If obstack alloc fails. -@end table +SYNOPSIS + asection * bfd_make_section(bfd *, CONST char *name); -*; PROTO(asection *, bfd_make_section, (bfd *, 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. + + Possible errors are: + o invalid_operation - If output has already started for this BFD. + o no_memory - If obstack alloc fails. */ @@ -385,19 +456,23 @@ DEFUN(bfd_make_section,(abfd, name), } -/*proto* bfd_set_section_flags -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: -@table @code -@item 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 table +/* +FUNCTION + bfd_set_section_flags + +SYNOPSIS + boolean bfd_set_section_flags(bfd *, asection *, flagword); + +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: + + o invalid operation + The section cannot have one or more of the attributes + requested. For example, a .bss section in <<a.out>> may not + have the <<SEC_HAS_CONTENTS>> field set. -*; PROTO(boolean, bfd_set_section_flags, - (bfd *, asection *, flagword)); */ boolean @@ -416,27 +491,28 @@ DEFUN(bfd_set_section_flags,(abfd, section, flags), } -/*proto* bfd_map_over_sections -Calls 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 +/* +FUNCTION + bfd_map_over_sections + +SYNOPSIS + void bfd_map_over_sections(bfd *abfd, void (*func)(), PTR obj); -@example - func(abfd, the_section, obj); -@end example +DESCRIPTION + Calls 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); -*; PROTO(void, bfd_map_over_sections, - (bfd *abfd, void (*func)(), PTR obj)); + This is the prefered method for iterating over sections, an + alternative would be to use a loop: + +| section *p; +| for (p = abfd->sections; p != NULL; p = p->next) +| func(abfd, p, ...) -This is the prefered 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 */ /*VARARGS2*/ @@ -457,18 +533,21 @@ DEFUN(bfd_map_over_sections,(abfd, operation, user_storage), } -/*proto* bfd_set_section_size -Sets @var{section} to the size @var{val}. If the operation is ok, then -@code{true} is returned, else @code{false}. +/* +FUNCTION + bfd_set_section_size + +SYNOPSIS + boolean bfd_set_section_size(bfd *, asection *, bfd_size_type val); -Possible error returns: -@table @code -@item invalid_operation -Writing has started to the BFD, so setting the size is invalid -@end table +DESCRIPTION + Sets @var{section} to the size @var{val}. If the operation is + ok, then <<true>> is returned, else <<false>>. + + Possible error returns: + o invalid_operation + Writing has started to the BFD, so setting the size is invalid -*; PROTO(boolean, bfd_set_section_size, - (bfd *, asection *, bfd_size_type val)); */ boolean @@ -490,27 +569,35 @@ DEFUN(bfd_set_section_size,(abfd, ptr, val), return true; } -/*proto* bfd_set_section_contents -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} bytes. - -Normally @code{true} is returned, else @code{false}. Possible error -returns are: -@table @code -@item 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 table -This routine is front end to the back end function @code{_bfd_set_section_contents}. - -*; PROTO(boolean, bfd_set_section_contents, +/* +FUNCTION + bfd_set_section_contents + +SYNOPSIS + boolean bfd_set_section_contents (bfd *abfd, asection *section, PTR data, file_ptr offset, - bfd_size_type count)); + bfd_size_type count); + + +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} bytes. + + Normally <<true>> is returned, else <<false>>. Possible error + returns are: + o no_contents + The output section does not have the <<SEC_HAS_CONTENTS>> + attribute, so nothing can be written to it. + o and some more too + + This routine is front end to the back end function + <<_bfd_set_section_contents>>. + */ @@ -538,25 +625,26 @@ DEFUN(bfd_set_section_contents,(abfd, section, location, offset, count), return false; } -/*proto* bfd_get_section_contents -This function reads 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. +/* +FUNCTION + bfd_get_section_contents -If the contents of a constuctor with the @code{SEC_CONSTUCTOR} flag -set are requested, then the @var{location} is filled with zeroes. +SYNOPSIS + boolean bfd_get_section_contents + (bfd *abfd, asection *section, PTR location, + file_ptr offset, bfd_size_type count); -If no errors occur, @code{true} is returned, else @code{false}. -Possible errors are: +DESCRIPTION + This function reads 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. -@table @code -@item unknown yet -@end table + If the contents of a constuctor with the <<SEC_CONSTUCTOR>> + flag set are requested, then the @var{location} is filled with + zeroes. If no errors occur, <<true>> is returned, else + <<false>>. -*; PROTO(boolean, bfd_get_section_contents, - (bfd *abfd, asection *section, PTR location, - file_ptr offset, bfd_size_type count)); */ |