Symbols are a key part of GDB's operation. Symbols include variables, functions, and types.
½Éº¼Àº GDB ÀÛµ¿¿¡¼ Áß¿äÇÑ ºÎºÐÀÌ´Ù. ½Éº¼Àº º¯¼ö, ÇÔ¼ö ±×¸®°í ŸÀÔÀ» Æ÷ÇÔÇÑ´Ù.
GDB reads symbols from symbol files. The usual symbol file is the file containing the program which GDB is debugging. GDB can be directed to use a different file for symbols (with the `symbol-file' command), and it can also read more symbols via the `add-file' and `load' commands, or while reading symbols from shared libraries.
GDB´Â symbol files¿¡¼ ½Éº¼À» Àд´Ù. ÀϹÝÀûÀÎ ½Éº¼ ÆÄÀÏÀº GDB°¡ µð¹ö±ëÇÏ´Â ÇÁ·Î±×·¥À» Æ÷ÇÔÇÑ ÆÄÀÏÀÌ´Ù. GDB´Â ½Éº¼(`symbol-file' ¸í·É¾î·Î)À» À§ÇØ ´Ù¸¥ ÆÄÀÏÀ» »ç¿ëÇϵµ·Ï Áö½ÃÇÒ¼ö ÀÖÀ¸¸ç `add-file'¿Í `load' ¸í·É¾î¸¦ ÅëÇØ ´õ ¸¹Àº ½Éº¼À» ÀÐÀ»¼ö ÀÖÀ¸¸ç ¶Ç °øÀ¯ ¶óÀ̺귯¸®¿¡¼ ½Éº¼À» ÀÐÀ»¼ö ÀÖ´Ù.
Symbol files are initially opened by code in `symfile.c' using
the BFD library (see section Support Libraries). BFD identifies the type
of the file by examining its header. find_sym_fns
then uses
this identification to locate a set of symbol-reading functions.
½Éº¼ ÆÄÀÏÀº BFD ¶óÀ̺귯¸®(Support Libraries ¼½¼ÇÀ» ÂüÁ¶Çضó.)¸¦ »ç¿ëÇÏ´Â `symfile.c'³» Äڵ忡 ÀÇÇØ
¿¸°´Ù. BFD´Â Çì´õ¸¦ °Ë»çÇÏ¿© ÆÄÀÏÀÇ Å¸ÀÔÀ» ½Äº°ÇÑ´Ù.
±×¸®°í find_sym_fns
´Â ½Éº¼-Àд ÇÔ¼ö ÁýÇÕÀ» À§Ä¡½ÃÅ°±â À§ÇØ
ÀÌ ½Äº°À» »ç¿ëÇÑ´Ù.
Symbol-reading modules identify themselves to GDB by calling
add_symtab_fns
during their module initialization. The argument
to add_symtab_fns
is a struct sym_fns
which contains the name (or name prefix) of the symbol format, the length of the prefix,
and pointers to four functions. These functions are called at various
times to process symbol files whose identification matches the specified
prefix.
½Éº¼-Àб⠸ðµâÀº ¸ðµâ Ãʱâȵ¿¾È add_symtab_fns
¸¦ È£ÃâÇÏ¿©
GDB¿¡¼ ±×°ÍµéÀ» ½Äº°ÇÑ´Ù.
add_symtab_fns
¿¡ ´ëÇÑ ÀÎÀÚ´Â ½Éº¼ Çü½ÄÀÇ À̸§, Á¢µÎ»çÀÇ ±æÀÌ,
±×¸®°í ³× ÇÔ¼ö¿¡ ´ëÇÑ Æ÷ÀÎÅ͸¦ Æ÷ÇÔÇÏ´Â struct sym_fns
ÀÌ´Ù.
À̵é ÇÔ¼ö´Â ÁöÁ¤µÈ Á¢µÎ»ç¿Í ÀÏÄ¡ÇÏ¿© ½Äº°µÈ ½Éº¼ ÆÄÀÏÀ» ó¸®Çϱâ À§ÇØ ¿©·¯¹ø
È£ÃâµÈ´Ù.
The functions supplied by each module are:
°¢ ¸ðµâÀÌ Á¦°øÇÏ´Â ÇÔ¼ö´Â:
xyz_symfile_init(struct sym_fns *sf)
symbol_file_add
when we are about to read a new
symbol file. This function should clean up any internal state (possibly
resulting from half-read previous files, for example) and prepare to
read a new symbol file. Note that the symbol file which we are reading
might be a new "main" symbol file, or might be a secondary symbol file
whose symbols are being added to the existing symbol table.
»õ ½Éº¼ ÆÄÀÏÀ» ÀÐÀ»¶§ symbol_file_add
¿¡¼ È£ÃâµÈ´Ù.
ÀÌ ÇÔ¼ö´Â ³»ºÎ »óÅÂ(¿¹¸¦ µé¾î half-read Àü ÆÄÀÏÀÇ °á°ú)¸¦ ºñ¿ì°í »õ ½Éº¼ ÆÄÀÏÀ» ÀÐÀ»
Áغñ¸¦ ÇÑ´Ù.
¿ì¸®°¡ Àд ½Éº¼ ÆÄÀÏÀº »õ·Î¿î "main" ½Éº¼ ÆÄÀÏÀ̰ųª Á¸ÀçÇÏ´Â ½Éº¼ Å×ÀÌºí¿¡ Ãß°¡µÈ
ÀÌÂ÷ ½Éº¼ ÆÄÀÏÀÌ´Ù.
The argument to xyz_symfile_init
is a newly allocated
struct sym_fns
whose bfd
field contains the BFD for the
new symbol file being read. Its private
field has been zeroed,
and can be modified as desired. Typically, a struct of private
information will be malloc
'd, and a pointer to it will be placed
in the private
field.
There is no result from xyz_symfile_init
, but it can call
error
if it detects an unavoidable problem.
xyz_symfile_init
¿¡ ´ëÇÑ ÀÎÀÚ´Â »õ·Î Ç×´çµÈ struct sym_fns
À̸ç bfd
´Â Àд »õ·Î¿î ½Éº¼ ÆÄÀÏÀ» À§ÇØ BFD¸¦ Æ÷ÇÔÇÑ´Ù.
private
Çʵå´Â 0ÀÌ¸ç ¿øÇÏ¸é ¼öÁ¤ÇÒ¼ö ÀÖ´Ù. ÀüÇüÀûÀ¸·Î °³ÀÎ Á¤º¸ ±¸Á¶´Â
malloc
µÇ¸ç ÀÌ°Í¿¡ ´ëÇÑ Æ÷ÀÎÅÍ´Â private
Çʵ忡 ³õÀδÙ.
xyz_symfile_init
ÀÇ °á°ú´Â ¾Æ´ÏÁö¸¸ ¸¸ÀÏ ÇÇÇÒ¼ö ¾ø´Â ¹®Á¦°¡ ¹ß°ßµÈ´Ù¸é
error
¸¦ È£ÃâÇÑ´Ù.
xyz_new_init()
symbol_file_add
when discarding existing symbols.
This function needs only handle the symbol-reading module's internal
state; the symbol table data structures visible to the rest of
GDB will be discarded by symbol_file_add
. It has no
arguments and no result. It may be called after
xyz_symfile_init
, if a new symbol table is being read, or
may be called alone if all symbols are simply being discarded.
Á¸ÀçÇÏ´Â ½Éº¼À» ¹ö¸±¶§ symbol_file_add
¿¡¼ È£ÃâµÈ´Ù.
ÀÌ ÇÔ¼ö´Â ½Éº¼-Àд ¸ðµâÀÇ ³»ºÎ »óŸ¦ ó¸®ÇÒ¶§¸¸ ÇÊ¿äÇÏ´Ù.; GDB ³ª¸ÓÁö¸¦ ºñÁÖ¾óÇÏ°Ô ÇÏ´Â
½Éº¼ Å×ÀÌºí µ¥ÀÌÅÍ ±¸Á¶´Â symbol_file_add
¿¡ ÀÇÇØ ¹ö·ÁÁø´Ù.
ÀÎÀÚµµ ¾ø°í ¹Ýȯ°ªµµ ¾ø´Ù. ¸¸ÀÏ »õ·Î¿î ½Éº¼ Å×À̺íÀ» Àд´ٸé xyz_symfile_init
´ÙÀ½¿¡ È£ÃâµÇ°Å³ª, ¸¸ÀÏ ¸ðµç ½Éº¼ÀÌ ´Ü¼øÈ÷ ¹ö·ÁÁø´Ù¸é È£ÃâµÈ´Ù.
xyz_symfile_read(struct sym_fns *sf, CORE_ADDR addr, int mainline)
symbol_file_add
to actually read the symbols from a
symbol-file into a set of psymtabs or symtabs.
sf
points to the struct sym_fns
originally passed to
xyz_sym_init
for possible initialization. addr
is
the offset between the file's specified start address and its true
address in memory. mainline
is 1 if this is the main symbol
table being read, and 0 if a secondary symbol file (e.g. shared library
or dynamically loaded file) is being read.
½Éº¼ ÆÄÀÏÀÇ psymtabÀ̳ª symtab ÁýÇÕ¿¡¼ ½Éº¼À» Àбâ À§ÇØ symbol_file_add
¿¡¼
È£ÃâµÈ´Ù.
sf
´Â °¡´ÉÇÑ Ãʱâȸ¦ À§ÇØ xyz_sym_init
¿¡ Àü´ÞµÇ´Â struct sym_fns
¿¡ ´ëÇÑ Æ÷ÀÎÅÍÀÌ´Ù. addr
´Â ÆÄÀÏÀÌ ÁöÁ¤ÇÑ ½ÃÀÛÁÖ¼Ò¿Í
¸Þ¸ð¸®³» ½ÇÁ¦ ÁÖ¼Ò »çÀÌÀÇ offsetÀÌ´Ù. mainline
´Â ¸¸ÀÏ ÀÌ°ÍÀÌ ÀÐÀº ¸ÞÀÎ ½Éº¼
Å×À̺íÀ̶ó¸é 1, ¸¸ÀÏ 2Â÷ ½Éº¼ ÆÄÀÏ(Áï, °øÀ¯ ¶óÀ̺귯¸®³ª µ¿ÀûÀ¸·Î ·ÎµùµÈ ÆÄÀÏ)ÀÌ Àоú´Ù¸é 0
ÀÌ´Ù.
In addition, if a symbol-reading module creates psymtabs when
xyz_symfile_read is called, these psymtabs will contain a pointer
to a function xyz_psymtab_to_symtab
, which can be called
from any point in the GDB symbol-handling code.
°Ô´Ù°¡ ¸¸ÀÏ ½Éº¼ Àд ¸ðµâÀÌ xyz_symfile_read°¡ È£ÃâµÉ¶§ psymtabsÀ» ¸¸µç´Ù¸é,
À̵é psymtabsÀº GDB ½Éº¼ Çڵ鸵 Äڵ峻 ¾î¶² Æ÷ÀÎÆ®¿¡¼ È£ÃâµÇ´Â ÇÔ¼ö xyz_psymtab_to_symtab
¿¡ ´ëÇÑ Æ÷ÀÎÅ͸¦ Æ÷ÇÔÇÑ´Ù.
xyz_psymtab_to_symtab (struct partial_symtab *pst)
psymtab_to_symtab
(or the PSYMTAB_TO_SYMTAB
macro) if
the psymtab has not already been read in and had its pst->symtab
pointer set. The argument is the psymtab to be fleshed-out into a
symtab. Upon return, pst->readin
should have been set to 1, and
pst->symtab
should contain a pointer to the new corresponding symtab, or
zero if there were no symbols in that part of the symbol file.
¸¸ÀÏ psymtabÀÌ ÀÌ¹Ì ÀÐÇôÁöÁö ¾Ê°í pst->symtab
Æ÷ÀÎÅÍ ÁýÇÔÀ» °¡Áö°í
ÀÖ´Ù¸é psymtab_to_symtab
(¶Ç´Â PSYMTAB_TO_SYMTAB
¸ÅÅ©·Î)¿¡¼ È£ÃâµÈ´Ù.
ÀÎÀÚ´Â symtab°ú ÀÏÄ¡ÇÏÁö ¾Ê°Ô Çϱâ À§ÇÑ psymtabÀÌ´Ù. ¹Ýȯ½Ã, pst->readin
´Â
1·Î ¼³Á¤µÇ¾î¾ß Çϸç pst->symtab
´Â »õ·Î¿î ÇØ´ç symtab¿¡ ´ëÇÑ Æ÷ÀÎÅ͸¦ Æ÷ÇÔÇؾß
Çϸç, ¸¸ÀÏ ½Éº¼ ÆÄÀÏÀÇ ÀϺκп¡ ½Éº¼ÀÌ ¾ø´Ù¸é, 0À» Æ÷ÇÔÇØ¾ß ÇÑ´Ù.
GDB has three types of symbol tables:
GDB´Â ¼¼ ŸÀÔÀÇ ½Éº¼ Å×À̺íÀ» °¡Áö°í ÀÖ´Ù:
¿ÏÀüÇÑ ½Éº¼ Å×À̺í(symtabs). ÀÌ°ÍÀº ½Éº¼°ú ÁÖ¼Ò¿¡ °üÇÑ ÁÖ Á¤º¸¸¦ Æ÷ÇÔÇÑ´Ù.
ºÎºÐÀûÀÎ ½Éº¼ Å×À̺í(psymtabs). ÀÌ°ÍÀº Àüü ½Éº¼ Å×ÀÌºí¿¡¼ °ü·ÃµÈ ºÎºÐÀ» ÀÐÀ»¶§ ¾Ë·ÁÁÙ ÃæºÐÇÑ Á¤º¸¸¦ Æ÷ÇÔÇÑ´Ù.
ÃÖ¼Ò ½Éº¼ Å×À̺í (msymtabs). ÀÌ°ÍÀº ºñ-µð¹ö±ë ½Éº¼¿¡¼ ¸ð¾ÆÁø Á¤º¸¸¦ Æ÷ÇÔÇÑ´Ù.
This section describes partial symbol tables.
ÀÌ ¼½¼ÇÀº ºÎºÐÀûÀÎ ½Éº¼ Å×À̺íÀ» ±â¼úÇÑ´Ù.
A psymtab is constructed by doing a very quick pass over an executable file's debugging information. Small amounts of information are extracted--enough to identify which parts of the symbol table will need to be re-read and fully digested later, when the user needs the information. The speed of this pass causes GDB to start up very quickly. Later, as the detailed rereading occurs, it occurs in small pieces, at various times, and the delay therefrom is mostly invisible to the user.
psymtabÀº ½ÇÇà ÆÄÀÏ µð¹ö±ë Á¤º¸¸¦ ¸Å¿ì ºü¸£°Ô Àü´ÞµÇµµ·Ï ¸¸µé¾î Á³´Ù. ÀÛÀº ¾çÀÇ Á¤º¸´Â ÀϺΠ½Éº¼ Å×À̺íÀ» ´Ù½Ã ÀÐÀ» ÇÊ¿ä°¡ ÀÖ´Ù´Â °ÍÀ» ¾Ë¾Æ³½´Ù. ±×¸®°í »ç¿ëÀÚ°¡ Á¤º¸°¡ ÇÊ¿äÇÒ¶§ ³ªÁß¿¡ ¿ÏÀüÈ÷ ¼ÒȵȴÙ. Àü´Þ ¼Óµµ´Â GDB°¡ ¸Å¿ì ºü¸£°Ô ½ÃÀÛÇϵµ·Ï ¾ß±âÇÑ´Ù. ³ªÁß¿¡, ¼¼ºÎÀûÀ¸·Î ´Ù½Ã ÀбⰡ ¹ß»ýÇÑ´Ù¸é, ¿©·¯¹ø ÀÛÀº ´ÜÀ§·Î ÀϾ¸ç ±×·¯ÇÑ µô·¹ÀÌ´Â »ç¿ëÀÚµéÀÌ °¡Àå º¼¼ö ¾ø´Â°ÍÀÌ´Ù.
The symbols that show up in a file's psymtab should be, roughly, those
visible to the debugger's user when the program is not running code from
that file. These include external symbols and types, static symbols and
types, and enum
values declared at file scope.
ÆÄÀÏÀÇ psymtab¿¡¼ º¸¿©ÁÖ´Â ½Éº¼Àº ÇÁ·Î±×·¥ÀÌ ÇØ´ç ÆÄÀÏ¿¡¼ µ¹¾Æ°¡´Â Äڵ尡 ¾Æ´Ò¶§
µð¹ö°Å »ç¿ëÀÚ¿¡°Ô À̰͵éÀ» º¸¿©Áà¾ß ÇÑ´Ù. À̰͵éÀº ¿ÜºÎ ½Éº¼°ú ŸÀÔ, Á¤Àû ½Éº¼°ú ŸÀÔ,
±×¸®°í ÆÄÀÏ ¹üÀ§³» ¼±¾ðµÈ enum
º¯¼ö¸¦ Æ÷ÇÔÇÑ´Ù.
The psymtab also contains the range of instruction addresses that the full symbol table would represent.
psymtabÀº Àüü ½Éº¼ Å×À̺íÀÌ ³ªÅ¸³»´Â ¸í·É¾î ÁÖ¼ÒÀÇ ¹üÀ§¸¦ Æ÷ÇÔÇÑ´Ù.
The idea is that there are only two ways for the user (or much of the code in the debugger) to reference a symbol:
idea´Â ½Éº¼À» ÂüÁ¶Çϱâ À§ÇØ »ç¿ëÀÚ(¶Ç´Â µð¹ö°Å³» ¸¹Àº ÄÚµå)¿¡°Ô´Â 2°¡ÁöÀÇ ¹æ¹ýÀÌ ÀÖ´Ù´Â °ÍÀÌ´Ù.
find_pc_function
, find_pc_line
, and other
find_pc_...
functions handle this.
ÁÖ¼Ò·Î (e.g. ½ÇÇàÀº ÆÄÀÏ¿¡¼ ÇÔ¼ö³» ÀϺΠÁÖ¼Ò¿¡¼ ¸ØÃá´Ù.)
ÁÖ¼Ò´Â ÀÌ psymtabÀÇ ¹üÀ§³»¿¡¼ Àνĵǰí Àüü symtabÀº ÀÐÇôÁø´Ù.
find_pc_function
, find_pc_line
, ±×¸®°í ´Ù¸¥ find_pc_...
ÇÔ¼ö´Â ÀÌ°ÍÀ» ó¸®ÇÑ´Ù.
lookup_symbol
does most of the work here.
À̸§À¸·Î (e.g. »ç¿ëÀÚ´Â º¯¼ö³ª ÇÔ¼ö³» breakpoint ¼³Á¤À» Ãâ·ÂÇϵµ·Ï ¿ä±¸ÇÑ´Ù.)
Àü¿ª À̸§°ú ÆÄÀÏ ¹üÀ§ À̸§Àº psymtab¿¡¼ ¹ß°ßµÇ¸ç, »Ì¾Æ³»µµ·Ï symtabÀ» ¾ß±âÇÑ´Ù.
Áö¿ª À̸§Àº Àü¿ª À̸§À̳ª ÆÄÀÏ ¹üÀ§ À̸§À¸·Î ÀÚ°ÝÀÌ ÁÖ¾îÁö¸ç ±×·± °æ¿ì ¿ì¸®´Â ÀÚ°ÝÀÌ ÀÖ´Â
À̸§À» Æò°¡Çϱâ À§ÇØ symtabÀ» Àд´Ù.
¶Ç´Â, Áö¿ª ½Éº¼Àº ¿ì¸®°¡ Áö¿ª ¹üÀ§³» ÀÖÀ»¶§ ÂüÁ¶µÉ¼ö ÀÖÀ¸¸ç, ±×·± °æ¿ì óÀ½ °æ¿ì°¡ Àû¿ëµÈ´Ù.
lookup_symbol
Àº ¿©±â¼ ÀÛ¾÷ÀÇ ´ëºÎºÐÀ» ÇÑ´Ù.
The only reason that psymtabs exist is to cause a symtab to be read in at the right moment. Any symbol that can be elided from a psymtab, while still causing that to happen, should not appear in it. Since psymtabs don't have the idea of scope, you can't put local symbols in them anyway. Psymtabs don't have the idea of the type of a symbol, either, so types need not appear, unless they will be referenced by name.
psymtabÀÌ Á¸ÀçÇÏ´Â À¯ÀÏÇÑ ÀÌÀ¯´Â Àû´çÇÑ ¼ø°£¿¡ symtabÀ» Àеµ·Ï ¾ß±âÇÏ´Â °ÍÀÌ´Ù. psymtab¿¡¼ »ý·«µÉ¼ö ÀÖ´Â ½Éº¼Àº ³ªÅ¸³ªµµ·Ï ¾ß±âÇÏ´Â µ¿¾È¿¡µµ, ±×°÷¿¡¼ ³ªÅ¸³ª¼´Â ¾ÈµÈ´Ù. psymtabÀº ¹üÀ§¿¡ ´ëÇÑ ¾ÆÀ̵ð¾î¸¦ °¡Áö°í ÀÖÁö¸¸, ¿©·¯ºÐÀº ¾î¶µç Áö¿ª ½Éº¼À» ³õÀ»¼ö ¾ø´Ù. psymtabÀº ½Éº¼ ŸÀÔ¿¡ ´ëÇÑ ¾ÆÀ̵ð¾î¸¦ °¡Áö°í ÀÖÁö ¾Ê´Ù. ±×·¡¼ À̸§À¸·Î ÂüÁ¶ÇѴٴ°ÍÀ» Á¦¿ÜÇÑ´Ù¸é ŸÀÔÀº ³ªÅ¸³¯ ÇÊ¿ä°¡ ¾ø´Ù.
It is a bug for GDB to behave one way when only a psymtab has been read, and another way if the corresponding symtab has been read in. Such bugs are typically caused by a psymtab that does not contain all the visible symbols, or which has the wrong instruction address ranges.
psymtabÀÌ Àп©Áú¶§ ÇÏ´Â Çൿ°ú »óÀÀÇÏ´Â symtabÀÌ ÀÐÇôÁú¶§ ´Ù¸¥ ¹æ¹ýÀ¸·Î ÇൿÇÏ´Â °ÍÀº GDB ¹ö±×ÀÌ´Ù. ±×·± ¹ö±×´Â ÀüÇüÀûÀ¸·Î psymtabÀÌ ¸ðµç ºñÁ®ºí ½Éº¼À» Æ÷ÇÔÇÏÁö ¾Ê¾Æ¼°Å³ª À߸øµÈ ¸í·É¾î ÁÖ¼Ò ¹üÀ§¸¦ °¡Áö±â ¶§¹®ÀÌ´Ù.
The psymtab for a particular section of a symbol file (objfile) could be thrown away after the symtab has been read in. The symtab should always be searched before the psymtab, so the psymtab will never be used (in a bug-free environment). Currently, psymtabs are allocated on an obstack, and all the psymbols themselves are allocated in a pair of large arrays on an obstack, so there is little to be gained by trying to free them unless you want to do a lot more work.
½Éº¼ ÆÄÀÏ(objfile)ÀÇ Æ¯Á¤ ¼½¼ÇÀ» À§ÇÑ psymtabÀº symtabÀÌ ÀÐÇôÁøÈÄ ¹ö·ÁÁø´Ù. symtabÀº Ç×»ó psymtabÀü¿¡ °Ë»öµÇ¸ç, ±×·¡¼ psymtabÀº °áÄÚ »ç¿ë(buf-free environment)µÇÁö ¾Ê´Â´Ù. ÇöÀç, psymtabÀº obstack¿¡¼ ÇÒ´çµÇ¸ç ¸ðµç psymbolÀº obstack³» Ä¿´Ù¶õ ¹è¿½ÖÀ¸·Î ÇÒ´çµÈ´Ù. ±×·¡¼ ¸¸ÀÏ ¿©·¯ºÐÀÌ ´õ ¸¹ÀÌ ÀÏÇÏ±æ ¿øÇÏÁö ¾Ê´Â´Ù¸é ±×°ÍµéÀ» ÇØÁ¦ÇÒ·Á°í ½ÃµµÇÏ¿© ¾ò´Â °ÍÀº °ÅÀÇ ¾ø´Ù.
FT_VOID
, FT_BOOLEAN
).FT_VOID
, FT_BOOLEAN
).These are the fundamental types that GDB uses internally. Fundamental types from the various debugging formats (stabs, ELF, etc) are mapped into one of these. They are basically a union of all fundamental types that GDB knows about for all the languages that GDB knows about.
À̰͵éÀº GDB°¡ ³»ºÎÀûÀ¸·Î »ç¿ëÇÏ´Â ±âº» ŸÀÔÀÌ´Ù. ´Ù¾çÇÑ µð¹ö±ë Çü½Ä(stab, ELF µî)¿¡¼ ±âº» ŸÀÔÀº À̰͵éÁß Çϳª·Î ´ëÀÀµÈ´Ù. ±×µéÀº ±âº»ÀûÀ¸·Î GDB°¡ ¾Ë°í ÀÖ´Â ¸ðµç ¾ð¾î¿¡ °üÇØ GDB°¡ ¾Ë°í ÀÖ´Â ¸ðµç ±âº» ŸÀÔ°ú °áÇÕÇÑ´Ù.
TYPE_CODE_PTR
, TYPE_CODE_ARRAY
).TYPE_CODE_PTR
, TYPE_CODE_ARRAY
).
Each time GDB builds an internal type, it marks it with one
of these types. The type may be a fundamental type, such as
TYPE_CODE_INT
, or a derived type, such as TYPE_CODE_PTR
which is a pointer to another type. Typically, several FT_*
types map to one TYPE_CODE_*
type, and are distinguished by
other members of the type struct, such as whether the type is signed
or unsigned, and how many bits it uses.
GDB´Â ¸Å¹ø ³»ºÎ ŸÀÔÀ» ¸¸µé¸ç, ÀÌ°ÍÀº À̵é ŸÀÔÁß Çϳª·Î Ç¥½ÃµÈ´Ù.
ŸÀÔÀº TYPE_CODE_INT
°°Àº ±âº» ŸÀÔÀ̰ųª Ÿ¸¥ ŸÀÔÀ» Æ÷ÀÎÅÍÇÏ´Â TYPE_CODE_PTR
°°Àº ÆÄ»ý ŸÀÔÀÌ´Ù.
ÀüÇüÀûÀ¸·Î, ¸î¸î FT_*
ŸÀÔÀº TYPE_CODE_*
ŸÀÔÀ¸·Î ´ëÀÀÇϸç
¾î¶² ŸÀÔÀÌ signÀ̳ª unsignÀÎÁö, ¾ó¸¶³ª ¸¹Àº ºñÆ®°¡ »ç¿ëµÇ´ÂÁö¿Í °°Àº ŸÀÔ ±¸Á¶ÀÇ
´Ù¸¥ ¸â¹öµé¿¡ ÀÇÇØ ±¸º°µÈ´Ù.
builtin_type_void
, builtin_type_char
).builtin_type_void
, builtin_type_char
).
These are instances of type structs that roughly correspond to
fundamental types and are created as global types for GDB to
use for various ugly historical reasons. We eventually want to
eliminate these. Note for example that builtin_type_int
initialized in `gdbtypes.c' is basically the same as a
TYPE_CODE_INT
type that is initialized in `c-lang.c' for
an FT_INTEGER
fundamental type. The difference is that the
builtin_type
is not associated with any particular objfile, and
only one instance exists, while `c-lang.c' builds as many
TYPE_CODE_INT
types as needed, with each one associated with
some particular objfile.
À̰͵éÀº ±âº» ŸÀÔ°ú °ü·ÃµÇ´Â ŸÀÔ ±¸Á¶ °´Ã¼ÀÌ¸ç ´Ù¾çÇÑ ¿ª»çÀûÀÎ ÀÌÀ¯·Î »ç¿ëµÇ´Â GDB
Àü¿ª ŸÀÔó·³ ¸¸µé¾îÁø´Ù. °á±¹ ¿ì¸®´Â À̰͵éÀ» ÁÙÀÌ±æ ¿øÇÑ´Ù. `gdbtypes.c'¿¡¼
ÃʱâȵǴ builtin_type_int
´Â ±âº»ÀûÀ¸·Î FT_INTEGER
±âº» ŸÀÔÀ»
À§ÇØ `c-lang.c'¿¡¼ ÃʱâȵǴ TYPE_CODE_INT
ŸÀÔ°ú °°´Ù.
´Ù¸¥ Á¡Àº builtin_type
´Â ¾î¶² ƯÁ¤ objfile°ú °ü·ÃÀÌ ¾øÀ¸¸ç ´ÜÁö °´Ã¼¸¸ Á¸ÀçÇÏ°í,
¹Ý¸é¿¡ `c-lang.c'´Â ¸î¸î ƯÁ¤ objfile°ú °ü·ÃµÉ¶§¸¶´Ù ÇÊ¿äÇÑ
TYPE_CODE_INT
ŸÀÔ ¸¸Å ¸¸µç´Ù.
The a.out
format is the original file format for Unix. It
consists of three sections: text
, data
, and bss
,
which are for program code, initialized data, and uninitialized data,
respectively.
a.out
Çü½ÄÀº UnixÀÇ ¿ø ÆÄÀÏ Çü½ÄÀÌ´Ù.
ÀÌ Çü½ÄÀº ¼¼ ¼½¼ÇÀ¸·Î ÀÌ·ç¾îÁ® ÀÖ´Ù:text
, data
, ±×¸®°í bss
,
°¢°¢Àº ÇÁ·Î±×·¥ ÄÚµå, ÃʱâÈµÈ µ¥ÀÌÅÍ, ÃʱâȵÇÁö ¾ÊÀº µ¥ÀÌÅÍÀÌ´Ù.
The a.out
format is so simple that it doesn't have any reserved
place for debugging information. (Hey, the original Unix hackers used
`adb', which is a machine-language debugger!) The only debugging
format for a.out
is stabs, which is encoded as a set of normal
symbols with distinctive attributes.
a.out
Çü½ÄÀº ¸Å¿ì ´Ü¼øÇÏ¸ç µð¹ö±ë Á¤º¸¸¦ À§ÇÑ Àå¼Ò¸¦ À¯ÁöÇÏÁö ¾Ê´Â´Ù.
(¿ø·¡ Unix ÇØÄ¿´Â ±â°è-¾ð¾î µð¹ö°ÅÀÎ `adb'¸¦ »ç¿ëÇÑ´Ù.)
a.out
¸¦ À§ÇÑ µð¹ö±ë Çü½ÄÀº stabÀ̸ç ÀÌ°ÍÀº ±¸º°ÀûÀΠƯ¼ºÀ» °¡Áö´Â º¸ÅëÀÇ ½Éº¼
ÁýÇÕó·³ ÀÎÄÚµùµÈ´Ù.
The basic a.out
reader is in `dbxread.c'.
±âº»ÀûÀÎ a.out
¸®´õ´Â `dbxread.c'¿¡ ÀÖ´Ù.
The COFF format was introduced with System V Release 3 (SVR3) Unix. COFF files may have multiple sections, each prefixed by a header. The number of sections is limited.
COFF Çü½ÄÀº System V Release 3(SVR3) Unix¿¡¼ ¼Ò°³µÇ¾ú´Ù. COFF ÆÄÀÏÀº ¿©·¯ ¼½¼ÇÀ» °¡Áö°í ÀÖÀ¸¸ç °¢°¢ Çì´õ°¡ Á¢µÎ»ç·Î ³õÀδÙ. ¼½¼ÇÀÇ ¼ö´Â Á¦ÇѵǾî ÀÖ´Ù.
The COFF specification includes support for debugging. Although this was a step forward, the debugging information was woefully limited. For instance, it was not possible to represent code that came from an included file.
COFF ¸í¼¼¼´Â µð¹ö±ë Áö¿øÀ» Æ÷ÇÔÇÑ´Ù. ºñ·Ï ÀÌ°ÍÀÌ ¾Õ ´Ü°è¶ó Çصµ, µð¹ö±ë Á¤º¸´Â Á¦ÇѵǾî ÀÖ´Ù. ¿¹¸¦µé¾î, Æ÷ÇÔµÈ ÆÄÀÏ¿¡¼ ¿Â Äڵ带 ³ªÅ¸³»´Â°ÍÀº °¡´ÉÇÏÁö ¾Ê´Ù.
The COFF reader is in `coffread.c'.
COFF ¸®´õ´Â `coffread.c'¿¡ ÀÖ´Ù.
ECOFF is an extended COFF originally introduced for Mips and Alpha workstations.
ECOFF´Â Mips¿Í Alpha workstationÀ» À§ÇØ ¼Ò°³µÈ È®ÀåµÈ COFFÀÌ´Ù.
The basic ECOFF reader is in `mipsread.c'.
±âº» ECOFF ¸®´õ´Â `mipsread.c'¿¡ ÀÖ´Ù.
The IBM RS/6000 running AIX uses an object file format called XCOFF.
The COFF sections, symbols, and line numbers are used, but debugging
symbols are dbx
-style stabs whose strings are located in the
.debug
section (rather than the string table). For more
information, see section `Top' in The Stabs Debugging Format.
IBM RS/6000¿¡¼ µ¹¾Æ°¡´Â AIX´Â XCOFF¶ó ºÒ¸®´Â °´Ã¼ ÆÄÀÏ Çü½ÄÀ» »ç¿ëÇÑ´Ù.
COFF ¼½¼Ç, ½Éº¼ ±×¸®°í ¶óÀÎ ³Ñ¹ö´Â »ç¿ëµÈ´Ù. ±×·¯³ª µð¹ö±ë ½Éº¼Àº ¹®ÀÚ¿ÀÌ .debug
¼½¼Ç(¹®ÀÚ¿ Å×ÀÌºí º¸´Ù´Â)¿¡ À§Ä¡ÇÏ´Â dbx
½ºÅ¸ÀÏ stabÀÌ´Ù.
´õ ¸¹Àº Á¤º¸¸¦ À§ÇØ The Stabs Debugging FormatÀÇ 'Top' ¼½¼ÇÀ» ÂüÁ¶Çضó.
The shared library scheme has a clean interface for figuring out what shared libraries are in use, but the catch is that everything which refers to addresses (symbol tables and breakpoints at least) needs to be relocated for both shared libraries and the main executable. At least using the standard mechanism this can only be done once the program has been run (or the core file has been read).
°øÀ¯ ¶óÀ̺귯¸® ±¸Á¶´Â °øÀ¯ ¶óÀ̺귯¸®°¡ »ç¿ëµÇ´Â ¹æ¹ýÀ» ÀÌÇØÇϱâ À§ÇÑ °£ÆíÇÑ ÀÎÅÍÆäÀ̽º¸¦ °¡Áö°í ÀÖÁö¸¸ catch´Â ÁÖ¼Ò¸¦ ÂüÁ¶ÇÏ´Â ¸ðµç °ÍÀº °øÀ¯ ¶óÀ̺귯¸®¿Í ¸ÞÀÎ ½ÇÇàÀ» À§ÇØ ÀçÇÒ´çÇÒ ÇÊ¿ä°¡ ÀÖ´Â °ÍÀÌ´Ù. Àû¾îµµ, ÀÌ·¸°Ô ÇÒ¼ö Àִ ǥÁØ ¸ÞÄ«´ÏÁîÀÇ »ç¿ëÀº µ¹¾Æ°¡´Â(¶Ç´Â ÄÚ¾î ÆÄÀÏÀ» Àд´Ù.) ÇÁ·Î±×·¥¿¡¼ ÇàÇØÁø´Ù.
Windows 95 and NT use the PE (Portable Executable) format for their executables. PE is basically COFF with additional headers.
Window 95¿Í NT´Â ½ÇÇàÀ» À§ÇØ PE(Portable Executable) Çü½ÄÀ» »ç¿ëÇÑ´Ù. PE´Â Ãß°¡ÀûÀÎ Çì´õ¸¦ °¡Áö´Â COFFÀÌ´Ù.
While BFD includes special PE support, GDB needs only the basic COFF reader.
BFD°¡ Ưº°ÇÑ PE Áö¿øÀ» Æ÷ÇÔÇÏ´Â ¹Ý¸é, GDB´Â ±âº» COFF ¸®´õ¸¸ÀÌ ÇÊ¿äÇÏ´Ù.
The ELF format came with System V Release 4 (SVR4) Unix. ELF is similar to COFF in being organized into a number of sections, but it removes many of COFF's limitations.
ELF Çü½ÄÀº System V Release 4(SVR4) À¯´Ð½º¿¡¼ ¿Ô´Ù. ELF´Â ¼½¼Ç¼ö·Î Á¶Á÷ȵǴ COFF¿Í ºñ½ÁÇÏÁö¸¸ COFFÀÇ Á¦ÇÑ °ªÀ» Á¦°ÅÇÏ¿´´Ù.
The basic ELF reader is in `elfread.c'.
±âº» ELF ¸®´õ´Â `elfread.c'¿¡ ÀÖ´Ù.
SOM is HP's object file and debug format (not to be confused with IBM's SOM, which is a cross-language ABI).
SOMÀº HPÀÇ °´Ã¼ ÆÄÀÏÀÌ¸ç µð¹ö±ë Çü½Ä(cross ¾ð¾î ABIÀÎ IBMÀÇ SOM°ú È¥µ¿ÇÏÁö ¸¶¶ó.)ÀÌ´Ù.
The SOM reader is in `hpread.c'.
SOM ¸®´õ´Â `hpread.c'¿¡ ÀÖ´Ù.
Other file formats that have been supported by GDB include Netware Loadable Modules (`nlmread.c').
GDB°¡ Áö¿øÇÏ´Â ´Ù¸¥ ÆÄÀÏ Çü½ÄÀº Netware Loadable Modules(`nlmread.c')À» Æ÷ÇÔÇÑ´Ù.
This section describes characteristics of debugging information that are independent of the object file format.
ÀÌ ¼½¼ÇÀº µ¶¸³ÀûÀÎ °´Ã¼ ÆÄÀÏ Çü½ÄÀÇ µð¹ö±ë Á¤º¸ÀÇ Æ¯¼ºÀ» ±â¼úÇÑ´Ù.
stabs
started out as special symbols within the a.out
format. Since then, it has been encapsulated into other file
formats, such as COFF and ELF.
stabs
´Â a.out
Çü½Ä³» Ưº°ÇÑ ½Éº¼Ã³·³ ½ÃÀÛÇÑ´Ù.
±×·¸±â ¶§¹®¿¡, COFF³ª ELF ó·³ ´Ù¸¥ ÆÄÀÏ Çü½ÄÀ¸·Î ĸ½¶ÈµÈ´Ù.
While `dbxread.c' does some of the basic stab processing, including for encapsulated versions, `stabsread.c' does the real work.
`dbxread.c'°¡ ĸ½¶ÈµÈ ¹öÀüÀ» Æ÷ÇÔÇÏ¿© ±âº» stab 󸮸¦ ÇÏ´Â µ¿¾È, `stabsread.c'´Â ½ÇÁ¦ ÀÛ¾÷À» ÇÑ´Ù.
The basic COFF definition includes debugging information. The level of support is minimal and non-extensible, and is not often used.
±âº» COFF Á¤ÀÇ´Â µð¹ö±ë Á¤º¸¸¦ Æ÷ÇÔÇÑ´Ù. Áö¿ø ·¹º§Àº ÃÖ¼ÒÀÌ°í ºñ È®ÀåÀ̸ç ÀÚÁÖ »ç¿ëµÇÁö ¾Ê´Â´Ù.
ECOFF includes a definition of a special debug format.
ECOFF´Â Ưº°ÇÑ µð¹ö±ë Çü½ÄÀÇ Á¤ÀǸ¦ Æ÷ÇÔÇÑ´Ù.
The file `mdebugread.c' implements reading for this format.
ÆÄÀÏ `mdebugread.c'´Â ÀÌ Çü½ÄÀ» À§ÇÑ Àб⸦ ¼öÇàÇÑ´Ù.
DWARF 1 is a debugging format that was originally designed to be used with ELF in SVR4 systems.
DWARF 1Àº SVR4 ½Ã½ºÅÛ¿¡¼ ELF¿Í ÇÔ²² »ç¿ëÇϱâ À§ÇØ µðÀÚÀÎµÈ µð¹ö±ë Çü½ÄÀÌ´Ù.
The DWARF 1 reader is in `dwarfread.c'.
DWARF 1 ¸®´õ´Â `dwarfread.c'¿¡ ÀÖ´Ù.
DWARF 2 is an improved but incompatible version of DWARF 1.
DWARF 2´Â Ç⼧µÇ¾úÁö¸¸ DWARF 1°ú´Â ȣȯµÇÁö ¾Ê´Â´Ù.
The DWARF 2 reader is in `dwarf2read.c'.
DWARF 2 ¸®´õ´Â `dwarf2read.c'¿¡ ÀÖ´Ù.
Like COFF, the SOM definition includes debugging information.
COFF ó·³, SOM Á¤ÀÇ´Â µð¹ö±ë Á¤º¸¸¦ Æ÷ÇÔÇÑ´Ù.
If you are using an existing object file format (a.out
, COFF, ELF, etc),
there is probably little to be done.
¸¸ÀÏ ¿©·¯ºÐÀÌ Á¸ÀçÇÏ´Â °´Ã¼ ÆÄÀÏ Çü½Ä(a.out
, COFF, ELF µî)À» »ç¿ëÇÑ´Ù¸é,
ÇؾßÇÒ°ÍÀÌ ¾Æ¸¶µµ °ÅÀÇ ¾ø´Ù.
If you need to add a new object file format, you must first add it to BFD. This is beyond the scope of this document.
¸¸ÀÏ ¿©·¯ºÐÀÌ »õ·Î¿î °´Ã¼ ÆÄÀÏ Çü½ÄÀ» Ãß°¡ÇÒ ÇÊ¿ä°¡ ÀÖ´Ù¸é, ¿©·¯ºÐÀº ¿ì¼± BFD¿¡ Ãß°¡ÇØ¾ß ÇÑ´Ù. ÀÌ°ÍÀº ÀÌ ¹®¼ÀÇ ¹üÀ§¸¦ ³Ñ¾î¼±´Ù.
You must then arrange for the BFD code to provide access to the debugging symbols. Generally GDB will have to call swapping routines from BFD and a few other BFD internal routines to locate the debugging information. As much as possible, GDB should not depend on the BFD internal data structures.
¿©·¯ºÐÀº µð¹ö±ë ½Éº¼¿¡ Á¢±ÙÀ» Á¦°øÇϱâ À§ÇØ BFD Äڵ带 Àç¹è¿ÇØ¾ß ÇÑ´Ù. ÀϹÝÀûÀ¸·Î GDB´Â BFD¿¡¼ swap ·çƾÀ» È£ÃâÇÏ°í µð¹ö±ë Á¤º¸¸¦ ã±â À§ÇØ ´Ù¸¥ BFD ³»ºÎ ·çƾÀ» È£ÃâÇÑ´Ù. °¡´ÉÇÑ ¸¹ÀÌ, GDB´Â BFD ³»ºÎ µ¥ÀÌÅÍ ±¸Á¶¿¡ ÀÇÁ¸ÇÏÁö ¾Ê¾Æ¾ß ÇÑ´Ù.
For some targets (e.g., COFF), there is a special transfer vector used to call swapping routines, since the external data structures on various platforms have different sizes and layouts. Specialized routines that will only ever be implemented by one object file format may be called directly. This interface should be described in a file `bfd/libxyz.h', which is included by GDB.
¸î¸î Ÿ°Ù(e.g., COFF)¸¦ À§ÇØ, swap ·çƾ È£Ãâ½Ã »ç¿ëÇϴ Ưº°ÇÑ Àü¼Û º¤ÅÍ°¡ ÀÖ´Ù. ¿Ö³ÄÇÏ¸é ´Ù¾çÇÑ Ç÷§Æû¿¡¼ ³»ºÎ µ¥ÀÌÅÍ ±¸Á¶´Â ´Ù¸¥ Å©±â¿Í ·¹À̾ƿôÀ» °¡Áö°í Àֱ⠶§¹®ÀÌ´Ù. ÇÑ °´Ã¼ ÆÄÀÏ Çü½Ä¿¡ ÀÇÇؼ ¼öÇàµÇ´Â ƯÁ¤ ·çƾµéÀº Á÷Á¢ È£ÃâµÈ´Ù. ÀÌ ÀÎÅÍÆäÀ̽º´Â GDB¿¡ Æ÷ÇÔµÈ `bfd/libxyz.h' ÆÄÀϳ»¿¡ ±â¼úµÇ¾î¾ß ÇÑ´Ù.
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