lf229, SoftwareDevelopment: GCC

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�� Lorne Bailey
<sherm_pbody(at)yahoo.com>

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Lorne�� Oracle � �� .

�� :
yacine laalaoui <yacine.laalaoui(at)caramail.com>

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�� GCC
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GCC - ��

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�� C � �� compilerGCC� �� C � �� ߡ � �� -debugger-

�� GCC

�� ޡ �� տ � �� п �� back door �� Trojan. �� Ken Thompso �� 'login'� � �� . �� .

�� GCC� �� configure; make; make install �� gcc �� . �� gcc �� ߡ �� ݡ �� С � �� C � �� gcc� �� gcc -E Pre-compile �� Compile gcc �� as Assembly �� Link ld

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#include <stdio.h>

int main()

{
  printf("Hello World!\n");
}

�� game.c �� :

gcc game.c

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a.out
Hello World

�� a.out �� . �� -o �� game ��. �� .

gcc -o game game.c

game
Hello World

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#ifndef DECK_H
#define DECK_H

#define DECKSIZE 52

typedef struct deck_t
{
  int card[DECKSIZE];
  /* number of cards used */
  int dealt;
}deck_t;

#endif /* DECK_H */

�� deck.h� �� game.c � �� "include "deck.h� �� deck_t deck;� �� ɡ �� .

gcc -o game game.c

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�� deck_t� ��  "deck.h"�� game.c�� #. �� -E �� gcc .

gcc -E -o game_precompile.txt game.c
wc -l game_precompile.txt
  3199 game_precompile.txt

�� game_precompile.txt �� 3200 �� stdio.h .

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�� #include . �� .
�� #define �� .
�� macro �� .

�� DECKSIZE �� ȡ �� ̡ �� .�� ǡ �� .

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�� assembly� � �� . �� .

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�� assembly code �� object code. �� -c �� .o

gcc -c game.c

�� ǡ � �� function �� 'drawn' �� .

#include <stdlib.h>
#include <stdio.h>
#include <time.h>
#include "deck.h"

static time_t seed = 0;

void shuffle(deck_t *pdeck)
{
  /* Keeps track of what numbers have been used */
  int drawn[DECKSIZE] = {0};
  int i;

  /* One time initialization of rand */
  if(0 == seed)
  {
    seed = time(NULL);
    srand(seed);
  }
  for(i = 0; i < DECKSIZE; i++)
  {
    int value = -1;
    do
    {
      value = rand() % DECKSIZE;
    }
    while(drawn[value] != 0);

    /* mark value as used */
    drawn[value] = 1;

    /* debug statement */
    printf("%i\n", value);
    pdeck->card[i] = value;
  }
  pdeck->dealt = 0;
  return;
}

�� shuffle.c� �� printf �� ǡ �� ( �� = debbuge) � �� .

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�� ( parameters) �� (pass) �� (by value)� �� (by address) �� "&" . �� ǡ �� global variables� �� ǡ � �� C �� .
�� main � �� shuffle.c �� .

��

gcc -c shuffle.c

�� shuffle.o �� shuffle.c . �� game.c � �� deck �� :

shuffle(&deck);

�� С ��

gcc -o game game.c

/tmp/ccmiHnJX.o: In function `main':
/tmp/ccmiHnJX.o(.text+0xf): undefined reference to `shuffle'
collect2: ld returned 1 exit status

�� . ��

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�� ء �� :

gcc -o game game.o shuffle.o

�� . �� shuffle.o � game.o �� main �� shuffle �� deck.h �� printf �� stdio.h .

��

�� -Wall �� :

game.c:9: warning: implicit declaration of function `shuffle'

�� shuffle �� deck.h �� :

void shuffle(deck_t *pdeck);

�� .

�� ( �� optimization) �� -#O �� -O2 �� ڡ �� ǡ �� ǡ �� 2 �� ..

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game | sort - n | less

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�� ( �� ) �� gdb �� KDbg �� . �� Kdbg �� file->executable � �� F5 �� File->Run �� :

gcc -g -c shuffle.c game.c
gcc -g -o game game.o shuffle.o

�� ̡ � �� gdb �� .

�� Kdbg � gdb �� ߡ � �� С �� shuffle �� ѡ �� F5 �� ʡ � �� F8 �� shuffle� � �� .

��

�� C � �� gcc . �� ( ��)� �� C � �� gcc � �� Kdbg � gdb.

� �� man � �� info �� gcc �� ld.

��

�� gcc GCC GNU
gdb GNU Debugger
KDbg KDE's GUI Debugger
Award Winning Compiler Hack Ken Thompson's great compiler hack

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en --> -- : Lorne Bailey <sherm_pbody(at)yahoo.com>

en --> ar: yacine laalaoui <yacine.laalaoui(at)caramail.com>

2002-05-09, generated by lfparser version 2.27

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