SECTION
Symbols
-DESCRIPTION
BFD trys to maintain as much symbol information as it can when
it moves information from file to file. BFD passes information
to applications though the <<asymbol>> structure. When the
- applicationrequests the symbol table, BFD reads the table in
+ application requests the symbol table, BFD reads the table in
the native form and translates parts of it into the internal
format. To maintain more than the infomation passed to
applications some targets keep some information 'behind the
information unique to coff which BFD doesn't know or
understand. If a coff symbol table was read, but was written
through an a.out back end, all the coff specific information
- would be lost. (.. until BFD 2 :). The symbol table of a BFD
+ would be lost. The symbol table of a BFD
is not necessarily read in until a canonicalize request is
made. Then the BFD back end fills in a table provided by the
application with pointers to the canonical information. To
like the linker to output a symbol as read, since the 'behind
the sceens' information will be still available.
@menu
-* Reading Symbols::
-* Writing Symbols::
-* typedef asymbol::
-* symbol handling functions::
+@* Reading Symbols::
+@* Writing Symbols::
+@* typedef asymbol::
+@* symbol handling functions::
@end menu
@node Reading Symbols, Writing Symbols, Symbols, Symbols
SUBSECTION
Reading Symbols
-DESCRIPTION
There are two stages to reading a symbol table from a BFD;
allocating storage, and the actual reading process. This is an
excerpt from an appliction which reads the symbol table:
-EXAMPLE
-
- unsigned int storage_needed;
- asymbol **symbol_table;
- unsigned int number_of_symbols;
- unsigned int i;
-
- storage_needed = get_symtab_upper_bound (abfd);
-
- if (storage_needed == 0) {
- return ;
- }
- symbol_table = (asymbol **) bfd_xmalloc (storage_needed);
- ...
- number_of_symbols =
- bfd_canonicalize_symtab (abfd, symbol_table);
-
- for (i = 0; i < number_of_symbols; i++) {
- process_symbol (symbol_table[i]);
- }
-
-DESCRIPTION
+| unsigned int storage_needed;
+| asymbol **symbol_table;
+| unsigned int number_of_symbols;
+| unsigned int i;
+|
+| storage_needed = get_symtab_upper_bound (abfd);
+|
+| if (storage_needed == 0) {
+| return ;
+| }
+| symbol_table = (asymbol **) bfd_xmalloc (storage_needed);
+| ...
+| number_of_symbols =
+| bfd_canonicalize_symtab (abfd, symbol_table);
+|
+| for (i = 0; i < number_of_symbols; i++) {
+| process_symbol (symbol_table[i]);
+| }
All storage for the symbols themselves is in an obstack
connected to the BFD, and is freed when the BFD is closed.
SUBSECTION
Writing Symbols
-DESCRIPTION
Writing of a symbol table is automatic when a BFD open for
writing is closed. The application attaches a vector of
pointers to pointers to symbols to the BFD being written, and
which has been created using <<bfd_make_empty_symbol>>. An
example showing the creation of a symbol table with only one element:
-EXAMPLE
-#include "bfd.h"
-main()
-{
- bfd *abfd;
- asymbol *ptrs[2];
- asymbol *new;
-
- abfd = bfd_openw("foo","a.out-sunos-big");
- bfd_set_format(abfd, bfd_object);
- new = bfd_make_empty_symbol(abfd);
- new->name = "dummy_symbol";
- new->section = (asection *)0;
- new->flags = BSF_ABSOLUTE | BSF_GLOBAL;
- new->value = 0x12345;
-
- ptrs[0] = new;
- ptrs[1] = (asymbol *)0;
-
- bfd_set_symtab(abfd, ptrs, 1);
- bfd_close(abfd);
-}
-
-./makesym
-nm foo
-00012345 A dummy_symbol
-
+| #include "bfd.h"
+| main()
+| {
+| bfd *abfd;
+| asymbol *ptrs[2];
+| asymbol *new;
+|
+| abfd = bfd_openw("foo","a.out-sunos-big");
+| bfd_set_format(abfd, bfd_object);
+| new = bfd_make_empty_symbol(abfd);
+| new->name = "dummy_symbol";
+| new->section = bfd_make_section_old_way(abfd, ".text");
+| new->flags = BSF_GLOBAL;
+| new->value = 0x12345;
+|
+| ptrs[0] = new;
+| ptrs[1] = (asymbol *)0;
+|
+| bfd_set_symtab(abfd, ptrs, 1);
+| bfd_close(abfd);
+| }
+|
+| ./makesym
+| nm foo
+| 00012345 A dummy_symbol
-DESCRIPTION
Many formats cannot represent arbitary symbol information; for
instance the <<a.out>> object format does not allow an
arbitary number of sections. A symbol pointing to a section
*/
-/*doc*
+/*
@node typedef asymbol, symbol handling functions, Writing Symbols, Symbols
*/
/*
-TYPEDEF
+SUBSECTION
typedef asymbol
-DESCRIPTION
An <<asymbol>> has the form:
+*/
+
+/*
+CODE_FRAGMENT
+
.typedef struct symbol_cache_entry
.{
- A pointer to the BFD which owns the symbol. This information
- is necessary so that a back end can work out what additional
- (invisible to the application writer) information is carried
- with the symbol.
-
+. {* A pointer to the BFD which owns the symbol. This information
+. is necessary so that a back end can work out what additional
+. (invisible to the application writer) information is carried
+. with the symbol. *}
+.
. struct _bfd *the_bfd;
-
-The text of the symbol. The name is left alone, and not copied - the
-application may not alter it.
-
-. CONST char *name;
-
-The value of the symbol.
-
-. symvalue value;
-
-Attributes of a symbol:
-
+.
+. {* The text of the symbol. The name is left alone, and not copied - the
+. application may not alter it. *}
+. CONST char *name;
+.
+. {* The value of the symbol.*}
+. symvalue value;
+.
+. {* Attributes of a symbol: *}
+.
.#define BSF_NO_FLAGS 0x00
-
-The symbol has local scope; <<static>> in <<C>>. The value is
-the offset into the section of the data.
-
+.
+. {* The symbol has local scope; <<static>> in <<C>>. The value
+. is the offset into the section of the data. *}
.#define BSF_LOCAL 0x01
-
-The symbol has global scope; initialized data in <<C>>. The value
-is the offset into the section of the data.
-
+.
+. {* The symbol has global scope; initialized data in <<C>>. The
+. value is the offset into the section of the data. *}
.#define BSF_GLOBAL 0x02
-
-Obsolete
-
+.
+. {* Obsolete *}
.#define BSF_IMPORT 0x04
-
-The symbol has global scope, and is exported. The value is the offset
-into the section of the data.
-
+.
+. {* The symbol has global scope, and is exported. The value is
+. the offset into the section of the data. *}
.#define BSF_EXPORT 0x08
-
-The symbol is undefined. <<extern>> in <<C>>. The value has no meaning.
-
-.#define BSF_UNDEFINED 0x10
-
-The symbol is common, initialized to zero; default in <<C>>. The
-value is the size of the object in bytes.
-
-.#define BSF_FORT_COMM 0x20
-
-A normal <<C>> symbol would be one of:
-<<BSF_LOCAL>>, <<BSF_FORT_COMM>>, <<BSF_UNDEFINED>> or <<BSF_EXPORT|BSD_GLOBAL>>
-
-The symbol is a debugging record. The value has an arbitary meaning.
-
+.
+. {* The symbol is undefined. <<extern>> in <<C>>. The value has
+. no meaning. *}
+.#define BSF_UNDEFINED_OBS 0x10
+.
+. {* The symbol is common, initialized to zero; default in
+. <<C>>. The value is the size of the object in bytes. *}
+.#define BSF_FORT_COMM_OBS 0x20
+.
+. {* A normal C symbol would be one of:
+. <<BSF_LOCAL>>, <<BSF_FORT_COMM>>, <<BSF_UNDEFINED>> or
+. <<BSF_EXPORT|BSD_GLOBAL>> *}
+.
+. {* The symbol is a debugging record. The value has an arbitary
+. meaning. *}
.#define BSF_DEBUGGING 0x40
-
-The symbol has no section attached, any value is the actual value and
-is not a relative offset to a section.
-
-.#define BSF_ABSOLUTE 0x80
-
-Used by the linker
-
+.
+. {* Used by the linker *}
.#define BSF_KEEP 0x10000
.#define BSF_KEEP_G 0x80000
-
-Unused
-
+.
+. {* Unused *}
.#define BSF_WEAK 0x100000
.#define BSF_CTOR 0x200000
-.#define BSF_FAKE 0x400000
-
-The symbol used to be a common symbol, but now it is allocated.
-
+.
+. {* This symbol was created to point to a section *}
+.#define BSF_SECTION_SYM 0x400000
+.
+. {* The symbol used to be a common symbol, but now it is
+. allocated. *}
.#define BSF_OLD_COMMON 0x800000
-
-The default value for common data.
-
+.
+. {* The default value for common data. *}
.#define BFD_FORT_COMM_DEFAULT_VALUE 0
-
-In some files the type of a symbol sometimes alters its location
-in an output file - ie in coff a <<ISFCN>> symbol which is also <<C_EXT>>
-symbol appears where it was declared and not at the end of a section.
-This bit is set by the target BFD part to convey this information.
-
+.
+. {* In some files the type of a symbol sometimes alters its
+. location in an output file - ie in coff a <<ISFCN>> symbol
+. which is also <<C_EXT>> symbol appears where it was
+. declared and not at the end of a section. This bit is set
+. by the target BFD part to convey this information. *}
+.
.#define BSF_NOT_AT_END 0x40000
-
-Signal that the symbol is the label of constructor section.
-
+.
+. {* Signal that the symbol is the label of constructor section. *}
.#define BSF_CONSTRUCTOR 0x1000000
-
-Signal that the symbol is a warning symbol. If the symbol is a warning
-symbol, then the value field (I know this is tacky) will point to the
-asymbol which when referenced will cause the warning.
-
+.
+. {* Signal that the symbol is a warning symbol. If the symbol
+. is a warning symbol, then the value field (I know this is
+. tacky) will point to the asymbol which when referenced will
+. cause the warning. *}
.#define BSF_WARNING 0x2000000
-
-Signal that the symbol is indirect. The value of the symbol is a
-pointer to an undefined asymbol which contains the name to use
-instead.
-
+.
+. {* Signal that the symbol is indirect. The value of the symbol
+. is a pointer to an undefined asymbol which contains the
+. name to use instead. *}
.#define BSF_INDIRECT 0x4000000
-
+.
. flagword flags;
-
-A pointer to the section to which this symbol is relative, or 0 if the
-symbol is absolute or undefined. Note that it is not sufficient to set
-this location to 0 to mark a symbol as absolute - the flag
-<<BSF_ABSOLUTE>> must be set also.
-
+.
+. {* A pointer to the section to which this symbol is
+. relative. This will always be non NULL, there are special
+. sections for undefined and absolute symbols *}
. struct sec *section;
-
-Back end special data. This is being phased out in favour of making
-this a union.
-
+.
+. {* Back end special data. This is being phased out in favour
+. of making this a union. *}
. PTR udata;
+.
.} asymbol;
-
*/
#include "bfd.h"
#include "sysdep.h"
#include "libbfd.h"
-#include "stab.gnu.h"
+#include "aout/stab_gnu.h"
/*
@node symbol handling functions, , typedef asymbol, Symbols
SUBSECTION
Symbol Handling Functions
-
*/
/*
{
fprintf_vma(file, symbol->value);
}
- fprintf(file," %c%c%c%c%c%c%c%c%c%c",
+ fprintf(file," %c%c%c%c%c%c%c%c",
(type & BSF_LOCAL) ? 'l':' ',
(type & BSF_GLOBAL) ? 'g' : ' ',
(type & BSF_IMPORT) ? 'i' : ' ',
(type & BSF_EXPORT) ? 'e' : ' ',
- (type & BSF_UNDEFINED) ? 'u' : ' ',
- (type & BSF_FORT_COMM) ? 'c' : ' ',
(type & BSF_CONSTRUCTOR) ? 'C' : ' ',
(type & BSF_WARNING) ? 'W' : ' ',
(type & BSF_INDIRECT) ? 'I' : ' ',
{
flagword flags = symbol->flags;
- if (flags & BSF_FORT_COMM) return 'C';
- if (flags & BSF_UNDEFINED) return 'U';
- if (flags & BSF_ABSOLUTE)
- return (flags & BSF_GLOBAL) ? 'A' : 'a';
+ if (symbol->section == &bfd_com_section) return 'C';
+ if (symbol->section == &bfd_und_section) return 'U';
if ( flags & (BSF_GLOBAL|BSF_LOCAL) ) {
- if (symbol->section == (asection *)NULL)
- return '*';
+ if ( symbol->section == &bfd_abs_section)
+ return (flags & BSF_GLOBAL) ? 'A' : 'a';
else if ( !strcmp(symbol->section->name, ".text") )
return (flags & BSF_GLOBAL) ? 'T' : 't';
else if ( !strcmp(symbol->section->name, ".data") )
return '?';
}
+
+
+bfd_symbol_is_absolute()
+{
+
+ abort();
+}
+
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