Jserv's blog

夢想、希冀、實踐

"It has often proved true that the dream of yesterday is the hope of today, and the reality of tomorrow."

• 「胡扯！癡人說夢，別提了」
• 「這或許是可行，但值得嗎？」
• 「我早就說這是個好主意！」

「所有能被發明的東西，都早已被發明出來了」

有隱士般的靈魂
蟄伏寄居於
自足的靜謐裡
有星星般的靈魂
疏離錯落於
寂寥的蒼穹上
有拓荒者般的靈魂
篳路藍縷的作為新路標
立於高速公路未曾鋪設的地段
但讓我站於道路的一旁
成為人類的
一位朋友

"the dream of yesterday is the hope of today,
and the reality of tomorrow."

• Wikipedia - [Robert H. Goddard]
• Dr. David P. Stern, [Robert Goddard and His Rockets]

建立 Gtk+/WebKit 的 API 文件以加速開發流程

• 切換到 Gtk+/WebKit 原始檔目錄，注意，這裡指的是 top level 的 "WebKit" 目錄，所以目錄下應該要有 "JavaScriptCore", "WebCore", "WebKit" 等子目錄
• 解開筆者打包的組態設定：

    $ tar jxvf webkit-gtkdoc-stub.tar.bz2

• 切換到解開的 doc 目錄：

    $ cd WebKit/gtk/doc

• 由給定的 Makefile，呼叫 gtk-doc 工具組去產生必要的文件檔案：

    $ make

...
Computing chunks...
Writing WebKitWebSettings.html for refentry(WebKitWebSettings)
Writing WebKitWebFrame.html for refentry(WebKitWebFrame)
Writing WebKitWebHistoryItem.html for refentry(WebKitWebHistoryItem)
Writing WebKitWebView.html for refentry(WebKitWebView)
Writing WebKitWebBackForwardList.html for refentry(WebKitWebBackForwardList)
Writing WebKitNetworkRequest.html for refentry(WebKitNetworkRequest)
Writing ch01.html for chapter
Writing index.html for book(index)
Writing index.sgml for book(index)
Writing webkit.devhelp for book(index)
Writing webkit.devhelp2 for book(index)

$ mkdir -p ~/.local/share/gtk-doc/html
$ cp -af html ~/.local/share/gtk-doc/html/webkit

" vim macro to jump to devhelp topics.
function! DevHelpCurrentWord()
        let word = expand("<cword>")
        exe "!devhelp -s " . word
endfunction

" Example: bind <ESC>h to start devhelp and search for the word under the
" cursor
nmap <ESC>h :call DevHelpCurrentWord()<CR>

Who Call Me (更新版)

• 如何取得此 function 返回位址
• 如何依據返回位址查知函式名稱

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void test()
{
}

int main()
{
	test();
}

jserv@venux:~/whocallme$ gcc -o test test.c
jserv@venux:~/whocallme$ gdb ./test
GNU gdb 6.8-debian
Copyright (C) 2008 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later 
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
and "show warranty" for details.
This GDB was configured as "i486-linux-gnu"...
(gdb) b test
Breakpoint 1 at 0x8048397
(gdb) r
Starting program: /home/jserv/whocallme/test 

Breakpoint 1, 0x08048397 in test ()
Current language:  auto; currently asm
(gdb) info reg
eax            0xbff05fb4	-1074765900
ecx            0xbff05f30	-1074766032
edx            0x1	1
ebx            0xb7fceff4	-1208160268
esp            0xbff05f08	0xbff05f08
ebp            0xbff05f08	0xbff05f08
esi            0x80483d0	134513616
edi            0x80482e0	134513376
eip            0x8048397	0x8048397 <test+3>
eflags         0x282	[ SF IF ]
cs             0x73	115
ss             0x7b	123
ds             0x7b	123
es             0x7b	123
fs             0x0	0
gs             0x33	51
(gdb) disas test
Dump of assembler code for function test:
0x08048394 <test+0>:	push   %ebp
0x08048395 <test+1>:	mov    %esp,%ebp
0x08048397 <test+3>:	pop    %ebp
0x08048398 <test+4>:	ret    
End of assembler dump.
(gdb)

(gdb) p/x *0xbff05f08
$1 = 0xbff05f18

(gdb) p/x *(0xbff05f08+4)
$2 = 0x80483af

(gdb) disas main
Dump of assembler code for function main:
0x08048399 <main+0>:	lea    0x4(%esp),%ecx
0x0804839d <main+4>:	and    $0xfffffff0,%esp
0x080483a0 <main+7>:	pushl  -0x4(%ecx)
0x080483a3 <main+10>:	push   %ebp
0x080483a4 <main+11>:	mov    %esp,%ebp
0x080483a6 <main+13>:	push   %ecx
0x080483a7 <main+14>:	sub    $0x4,%esp
0x080483aa <main+17>:	call   0x8048394 <test>
0x080483af <main+22>:	add    $0x4,%esp
0x080483b2 <main+25>:	pop    %ecx
0x080483b3 <main+26>:	pop    %ebp
0x080483b4 <main+27>:	lea    -0x4(%ecx),%esp
0x080483b7 <main+30>:	ret    
End of assembler dump.
(gdb)

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#include <stdio.h>
void test()
{
	unsigned int *stack;
	asm ("movl %%ebp, %0\n"
	     : "=g"(stack));
	printf("Return address = 0x%x\n", *(stack+1));
}

int main()
{
	test();
}

jserv@venux:~/whocallme$ gcc -o test-1 test-1.c
jserv@venux:~/whocallme$ ./test-1 
Return address = 0x80483fd

$ gdb ./test-1
(gdb) disas main
Dump of assembler code for function main:
0x080483e7 <main+0>:	lea    0x4(%esp),%ecx
0x080483eb <main+4>:	and    $0xfffffff0,%esp
0x080483ee <main+7>:	pushl  -0x4(%ecx)
0x080483f1 <main+10>:	push   %ebp
0x080483f2 <main+11>:	mov    %esp,%ebp
0x080483f4 <main+13>:	push   %ecx
0x080483f5 <main+14>:	sub    $0x4,%esp
0x080483f8 <main+17>:	call   0x80483c4 <test>
0x080483fd <main+22>:	add    $0x4,%esp
0x08048400 <main+25>:	pop    %ecx
0x08048401 <main+26>:	pop    %ebp
0x08048402 <main+27>:	lea    -0x4(%ecx),%esp
0x08048405 <main+30>:	ret    
End of assembler dump.
(gdb)

jserv@venux:~/whocallme$ objdump -t ./test-1 | awk '{print $1" "$3" "$6}'|grep "F"
08048340 F __do_global_dtors_aux
080483a0 F frame_dummy
080484e8 O __FRAME_END__
08048480 F __do_global_ctors_aux
08048410 F __libc_csu_fini
08048310 F _start
080484ac F _fini
08048420 F __libc_csu_init
080483c4 F test
0804847a F .hidden
080483e7 F main
08048298 F _init

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#include <stdio.h>
#include <bfd.h>

int main(int argc, char *argv[])
{
	bfd *abfd;
	long storage_needed;  
	asymbol **symbol_table;
	long number_of_symbols;
	long i;
	char **matching;
	sec_ptr section;
	char *symbol_name; 
	long symbol_offset, section_vma, symbol_address;

	if (argc < 2)
		return 0;
	printf("Open %s\n", argv[1]);
	bfd_init();
	abfd = bfd_openr(argv[1],NULL);
	if (abfd == (bfd *) 0) {
		bfd_perror("bfd_openr");
		return -1; 
	}
	if (!bfd_check_format_matches(abfd, bfd_object, &matching)) {
		return -1;
	}      
	if (!(bfd_get_file_flags (abfd) & HAS_SYMS)) {
		printf("ERROR flag!\n");
		return -1;
	}
	/* 取得符號表大小 */
	storage_needed = bfd_get_symtab_upper_bound(abfd);
	if (storage_needed < 0)
		return -1;
	symbol_table = (asymbol **) xmalloc(storage_needed);
	/* 將符號表讀進所配置的記憶體裡(symbol_table), 並傳回符號表個數 */
	number_of_symbols = bfd_canonicalize_symtab(abfd, symbol_table);
	if (number_of_symbols < 0)
		return -1;
	for (i = 0; i < number_of_symbols; i++) {
		/* 檢查此符號是否為函式 */
		if (symbol_table[i]->flags & (BSF_FUNCTION|BSF_GLOBAL))	{
			/* 反查此函式所處的區段(section) 及
			                   區段位址(section_vma) */
			section = symbol_table[i]->section;
			section_vma = bfd_get_section_vma(abfd, section);
			/* 取得此函式的名稱(symbol_name)、
			               偏移位址(symbol_offset) */
			symbol_name = symbol_table[i]->name;
			symbol_offset = symbol_table[i]->value;
			/* 將此函式的偏移位址加上區段位址，則為此函式在執行時
			   的記憶體位址(symbol_address */
			symbol_address = section_vma + symbol_offset;
			/* 檢查此函式是否處在程式本文區段 */
			if (section->flags & SEC_CODE)
				printf("<%s> 0x%x 0x%x 0x%x\n",
				         symbol_name,  
				               section_vma,  
				                    symbol_offset,
				                         symbol_address);
		}
	}
	bfd_close(abfd);
}

jserv@venux:~/whocallme$ gcc -o bfd bfd.c -lbfd
jserv@venux:~/whocallme$ ./bfd test-1
Open test-1
<__do_global_dtors_aux> 0x8048310 0x30 0x8048340
<frame_dummy> 0x8048310 0x90 0x80483a0
<__do_global_ctors_aux> 0x8048310 0x170 0x8048480
<__libc_csu_fini> 0x8048310 0x100 0x8048410
<_start> 0x8048310 0x0 0x8048310
<_fini> 0x80484ac 0x0 0x80484ac
<__libc_csu_init> 0x8048310 0x110 0x8048420
<test> 0x8048310 0xb4 0x80483c4
<__i686.get_pc_thunk.bx> 0x8048310 0x16a 0x804847a
<main> 0x8048310 0xd7 0x80483e7
<_init> 0x8048298 0x0 0x8048298

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/* bfd_dumpfun.c (GPL)
 *
 * Usage: ./bfd_dumpfun [binary]
 * Note: Dump functions infomation of ELF-binary with BFD Library.
 *     
 * by TimHsu(timhsu@info.sayya.org) 2004/03/31
 * Modified by Jim Huang <jserv.tw@gmail.com>, 2008/07/22
 *   - Bump bfd APIs and build fixes.
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <bfd.h>

typedef struct function_table FUN_TABLE;

/* 宣告一個包含函式名稱和位址的結構 */
struct function_table {
	char name[80];
	unsigned long addr;
};

static FUN_TABLE *fun_table;
static int table_count = 0;   /* 函式個數 */

static int compare_function(const void *a, const void *b)
{
	FUN_TABLE *aa = (FUN_TABLE *) a, *bb = (FUN_TABLE *) b;
	if (aa->addr > bb->addr)
		return 1;
	else if (aa->addr < bb->addr)
		return -1;
	return 0;  
}

/* 增加一個函式資料至對照表 */
static void add_function_table(char *name, unsigned long address)
{
	strncpy(fun_table[table_count].name, name, 80);
	fun_table[table_count].addr = address;
	table_count++;  
}

static void dump_function_table(void)
{
	int i;
	for (i = 0; i < table_count; i++) {
		printf("%-30s 0x%x\n",
		       fun_table[i].name, fun_table[i].addr);
	}
}

int main(int argc, char *argv[])
{
	bfd *abfd;
	asection *text;
	long storage_needed;
	asymbol **symbol_table;
	long number_of_symbols;
	long i;
	char **matching;
	sec_ptr section;
	char *symbol_name;
	long symbol_offset, section_vma, symbol_address;

	if (argc < 2) 
		return 0;
	printf("Open %s\n", argv[1]);
	bfd_init();
	abfd = bfd_openr(argv[1],NULL);
	if (abfd == (bfd *) 0) {
		bfd_perror("bfd_openr");
		return -1;
	}
	if (!bfd_check_format_matches(abfd, bfd_object, &matching)) {
		return -1;
	}      
	if (!(bfd_get_file_flags (abfd) & HAS_SYMS)) {
		printf("ERROR flag!\n");
		return -1;
	}
	if ((storage_needed = bfd_get_symtab_upper_bound(abfd)) < 0)
		return -1;
	symbol_table = (asymbol **) xmalloc(storage_needed);
	number_of_symbols = bfd_canonicalize_symtab(abfd, symbol_table);
	if (number_of_symbols < 0)
		return -1;
	fun_table = (FUN_TABLE **)malloc(sizeof(FUN_TABLE)*number_of_symbols);
	bzero(fun_table, sizeof(FUN_TABLE)*number_of_symbols);

	for (i = 0; i < number_of_symbols; i++) {
		if (symbol_table[i]->flags & (BSF_FUNCTION|BSF_GLOBAL)) {
			section = symbol_table[i]->section;
			section_vma = bfd_get_section_vma(abfd, section);
			symbol_name = symbol_table[i]->name;
			symbol_offset = symbol_table[i]->value;
			symbol_address = section_vma + symbol_offset;
			if (section->flags & SEC_CODE) {
				add_function_table(symbol_name,
				                   symbol_address);
			}
		}
	}
	bfd_close(abfd);
	/* 將函式對照表作排序 */
	qsort(fun_table, table_count, sizeof(FUN_TABLE), compare_function);
	dump_function_table();
}

jserv@venux:~/whocallme$ gcc -o bfd_dumpfun bfd_dumpfun.c -lbfd
jserv@venux:~/whocallme$ ./bfd_dumpfun ./test-1
Open ./test-1
_init                          0x8048298
_start                         0x8048310
__do_global_dtors_aux          0x8048340
frame_dummy                    0x80483a0
test                           0x80483c4
main                           0x80483e7
__libc_csu_fini                0x8048410
__libc_csu_init                0x8048420
__i686.get_pc_thunk.bx         0x804847a
__do_global_ctors_aux          0x8048480
_fini                          0x80484ac

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#include <stdio.h>

#define	FUNCTION_NAME_MAXLEN		80

#define who_call_me() \
	do { \
        	unsigned int *stack; \
		asm ("movl %%ebp, %0\n"  \
		     : "=g"(stack));  \
		fprintf(stderr, \
			"<whocallme>: function <%s> call me <%s>!\n", \
			find_function_by_addr(*(stack+1)), who_am_i()); \
	} while(0)

extern int init_function_table(char *);

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/* whocallme.c (GPL)
 *
 * A runtime backtrace of function. 
 * 
 * by Timhsu(timhsu@chroot.org) 2004/03/31
 * Modified by Jim Huang <jserv.tw@gmail.com>, 2008/07/22
 *   - Bump bfd APIs.
 *   - Eliminate compiler errors.
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <bfd.h>
#include "whocallme.h"

/* forward declarations */
char *find_function_by_addr(unsigned long addr);

typedef struct function_table FUN_TABLE;
/* 宣告一個包含函式名稱和位址的結構 */
struct function_table {
	char name[FUNCTION_NAME_MAXLEN];
  	unsigned long addr;
};

static FUN_TABLE *fun_table;
static int table_count = 0;	/* 函式個數 */

static int compare_function(const void *a, const void *b)
{
        FUN_TABLE *aa = (FUN_TABLE *) a;
        FUN_TABLE *bb = (FUN_TABLE *) b;
	if (aa->addr > bb->addr)
		return 1;
	else if (aa->addr < bb->addr)
		return -1;
	return 0;
}

/* 增加一個函式資料至對照表 */
static void add_function_table(char *name, unsigned long address)
{
	strncpy(fun_table[table_count].name, name, FUNCTION_NAME_MAXLEN);
	fun_table[table_count].addr = address;
	table_count++;
}

/* 取得目前正在執行的函式名稱 */
char * who_am_i(void)
{
        unsigned long *stack;   \
	asm ("movl %%ebp, %0\n"  \
		: "=g"(stack));         
	return find_function_by_addr(*(stack + 1));
}

/* 依照位址取得函式名稱 */
char *find_function_by_addr(unsigned long addr)
{
	int i;
	for (i = 0; i < table_count; i++) {
		if (addr > fun_table[i].addr) {
			if (addr < fun_table[i + 1].addr)
				return fun_table[i].name;
		}
	}
	return NULL;
}

/* 初始化函式對照表 */
int init_function_table(char *file)
{
	bfd *abfd;
	long storage_needed;
	asymbol **symbol_table;
	long number_of_symbols;
	long i;
	char **matching;
	sec_ptr section;
	char *symbol_name;
	long symbol_offset, section_vma, symbol_address;

	bfd_init();
	abfd = bfd_openr(file, NULL);
	if (abfd == (bfd *) 0) {
		bfd_perror("bfd_openr");
		return -1;
	}
	if (!bfd_check_format_matches(abfd, bfd_object, &matching)) {
		return -1;
	}	
	if (!(bfd_get_file_flags (abfd) & HAS_SYMS)) {
		printf("ERROR flag!\n");
		return -1;
	}
	/* 取得符號表大小 */
	storage_needed = bfd_get_symtab_upper_bound(abfd);
	if (storage_needed < 0)
		return -1;
	symbol_table = (asymbol **) malloc(storage_needed);
	/* 將符號表讀進所配置的記憶體裡(symbol_table), 並傳回符號表個數 */
	number_of_symbols = bfd_canonicalize_symtab(abfd, symbol_table);
	if (number_of_symbols < 0)
		return -1;
	/* 配置空間給函式對照表 */
	fun_table = (FUN_TABLE *) malloc(sizeof(FUN_TABLE) * number_of_symbols);
	bzero(fun_table, sizeof(FUN_TABLE)*number_of_symbols);

	for (i = 0; i < number_of_symbols; i++) {
		/* 檢查此符號是否為函式 */
		if (symbol_table[i]->flags & (BSF_FUNCTION|BSF_GLOBAL)) {
			/* 反查此函式所處的區段(section) 及區段位址(section_vma)*/ */
			section = symbol_table[i]->section;
			section_vma = bfd_get_section_vma(abfd, section);
			/* 取得此函式的名稱(symbol_name), 偏移位址(symbol_offset) */
			symbol_name = (char *) symbol_table[i]->name;
			symbol_offset = symbol_table[i]->value;
			/* 將此函式的偏移位址加上區段位址，則為此函式
			 * 在執行時的記憶體位址 (symbol_address) */
			symbol_address = section_vma + symbol_offset;
			/* 檢查此函式是否處在程式本文區段 */
			if (section->flags & SEC_CODE) {
				/* 將此函式名稱和位址加入至對照表 */
			add_function_table(symbol_name, 
						   symbol_address);
			}
		}
	}
	free(symbol_table);
	bfd_close(abfd);
	/* 將函式對照表作排序 */
	qsort(fun_table, table_count, sizeof(FUN_TABLE), compare_function);
	return 0;
}

jserv@venux:~/whocallme$ gcc -c whocallme.c
jserv@venux:~/whocallme$ ar -q libwhocallme.a whocallme.o

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22
23
24
25
26
27

#include "whocallme.h"

void test()
{
	who_call_me(); 
}
void test_a()
{
	test_b();
	test_c();
}
void test_b()
{
	test();
}
void test_c()
{
	who_call_me(); 
}
int main(int argc, char *argv[])
{
	init_function_table(argv[0]);
	test();
	test_a();      
	test_b();
	test_c();
}

jserv@venux:~/whocallme$ gcc -o test-2 test-2.c -lbfd -L. -lwhocallme
jserv@venux:~/whocallme$ ./test-2
: function <main> call me <test>!
: function <test_b> call me <test>!
: function <test_a> call me <test_c>!
: function <test_b> call me <test>!
: function <main> call me <test_c>!

在 vim 凸顯 Gtk+ 特有語法

:let glib_enable_deprecated = 1

「Gtk+ 程式設計初體驗」簡報上線

• [Gtk+ 程式設計初體驗::概念篇]
• [Gtk+ 程式設計初體驗::實務篇]

自由軟體教育訓練與演講規劃

「在一個企業裡，大多數員工其實都知道，多分享多學習是提高競爭力最好的方式，但在個人利益衝突與缺乏互信的考量下，員工卻因為害怕自己競爭力會因分享而降低，故選擇了藏私一途。對企業員工而言，員工選擇藏私的自利行為，並不會因此降低員工個體的競爭力，但對企業而言，越多藏私型的員 工，其整體競爭力將遠低具有互信與分享文化的企業。」

• 系統層面： GNU/Linux 系統概況與低階處理、Realtime Linux、系統層級開發工具、NetBSD 核心設計與開發、RTOS 設計與實做、x86/ARM/MIPS 硬體平台之開發、機器人平台
• 桌面技術與圖形處理： X Window System 概況與關鍵技術、桌面環境整合與客製化開發、輕量級桌面系統、3D/OpenGL 應用、引入 Web 技術之桌面環境設計、嵌入式系統中的圖形處理與應用、GNU/Linux 圖形系統、Qt/Gtk+ 開發
• VM (Virtual Machine)： Java VM 內部設計與實做考量、動態編譯器 (JIT/Hotspot)、效能調整與安全性強化
• 自由軟體授權與適用性範疇： 自由軟體與對應法律的疑慮、迴避 GNU GPL 授權衝擊的途徑、應用於消費性電子產品的自由軟體考量
• 開發工具： GNU Toolchains 概況與探討、版本控制與專案開發、整合開發工具的建構
• 多國語文處理： 國際化與區域化的資訊系統考量、CJK 通用漢語系統 / 中東語文資訊系統設計、輸入法架構
• 多媒體音訊視訊處理： MPEG 系統概況、視訊音訊編碼導論、VC-1 / China AVS 技術

透過 FreeType 繪製 Unicode ASCII Art

/* Taken from http://blog.chinaunix.net/u/8057/showart_335549.html
 * with slight modifications */
#include <ft2build.h>
#include FT_FREETYPE_H
#include <strings.h>

int main(int argc, char **argv)
{
	int psize;
	FT_Library library;
	FT_Face face;
	unsigned int ucode;
	FT_UInt glyph_index;
	int row, pixel;
	char *fp;

	if (argc != 4) {
		return 10;
	}

	ucode = strtol(argv[2], NULL, 16);
	psize = strtol(argv[3], NULL, 10);

	printf("unicode +%X size %d \n", ucode, psize);
	printf("font %s\n", (fp = rindex(argv[1], '/')) != NULL ?
	             fp  + 1 : argv[1]);
	if (FT_Init_FreeType(&library) ||
	    FT_New_Face(library, argv[1], 0, &face) ||
	    FT_Set_Pixel_Sizes(face, psize, 0)) {
		return 1;
	}

	glyph_index = FT_Get_Char_Index(face, ucode);
	if (glyph_index == 0) {
		return 2;
	}
	if (FT_Load_Glyph(face, glyph_index, FT_LOAD_DEFAULT)) {
		return 3;
	}
	if (FT_Render_Glyph(face->glyph, FT_RENDER_MODE_MONO)) {
		return 4;
	}

	/* FIXME: we shall reserve space for low length
	 * (face->glyph->bitmap.rows - face->glyph->bitmap_top)
	 */
	for (row = 0; row < face->glyph->bitmap.rows; ++row) {
		for (pixel = 0; pixel < face->glyph->bitmap_left; ++pixel)
			printf("_");
		for (pixel = 0; pixel < face->glyph->bitmap.width; ++pixel){
			if (face->glyph->bitmap.buffer
					[row * face->glyph->bitmap.pitch +
					 pixel / 8] & (0xC0 >> (pixel % 8)))
				printf("\033[44;37m" " " "\033[m");
			else
				printf("_");
		}
		printf("\n");
	}
	return 0;
}

• FT_Init_FreeType : 初始化 FreeType library 物件
• FT_New_Face : 呼叫 FT_Open_Face 開啟指定路徑的字型，建立 face 物件
• FT_Set_Pixel_Sizes : 呼叫 FT_Request_Size 以索取象徵性 (可能與實際描繪有出入) 的字型大小，單位 pixel
• FT_Get_Char_Index : 傳回給定字元碼的 glyph，本函數使用 charmap 物件去進行編碼的映射
• FT_Load_Glyph : 載入單一 glyph 資料到 face 物件中
• FT_Render_Glyph : 轉換給定的 glyph 圖形為點陣圖

$ gcc `pkg-config freetype2 --cflags --libs` -o ftart ftart.c -Wall

$ ./ftart \
    /usr/share/fonts/truetype/arphic/uming.ttc \
    `echo -n "群" | iconv -t ucs2 | od -tx1 | head -n1 | awk '{print $3$2}'` \
    24

「Gtk+ 程式設計初體驗」參考範例上線

• [webapp.c] (使用 Gtk+/WebKit 的應用程式)
  
  由圖可見，這是個左邊一個按鈕，右邊一個馬力歐遊戲的小程式，當然，遊戲本身是可以玩的，這需要幾行程式呢？
• [editor.c] (Gtk+ widget 展示)
  
  如上圖，這就是一個文字編輯器，完全支援 Unicode 與多行編輯，觀察看看，用幾行程式碼達成？
• [player.c] (使用 GStreamer 技術的範例)
  這是個可播放多媒體聲音 / 影像的小程式，雖然沒有華麗的介面，但就跟 MPlayer 一樣，忠實地處理指定網址 (包含 file:// ) 的多媒體檔案，這又需要多少程式碼呢？

• 物件導向的思維與實做：表面上都是 C 語言的 Gtk+，其實蘊含豐富的 OOP 機制，而物件導向更是深植於設計本體
• 視窗系統中的事件與其對應的操作處理：藉由範例程式的修改與調整，我們可即時窺見這些抽象概念的視覺具體呈現
• 圖形元件的設計概念與組合、互動形式：無疑地，這是 Gtk+/GNOME 技術引人入勝之處，只要施點魔力，就會浮現於我們面前
• MVC (Model-View-Control) 設計模式的引入：Gtk+ 到處可見到 Design Patterns，並以優雅的形式去將若干技術融會其中

• apt-get install build-essential
  很顯然，我們需要編譯 C/C++ 應用程式
• apt-get install libgtk2.0-dev
  主題是 Gtk+，當然要安裝其對應的開發套件
• apt-get install libwebkit-dev
  依據 debian 描述，該套件為 "Web content engine library for Gtk+"，注意，Qt 4.4 之後，也切割了 libqt4-webkit，表示 WebKit module for Qt，不要弄混淆了
• apt-get install gstreamer0.10-x gstreamer0.10-tools gstreamer0.10-ffmpeg gstreamer0.10-plugins-base gstreamer0.10-plugins-good gnome-media
  這是運作與開發 GStreamer 應用程式所需的套件，預先被妥善地切割，所以稍微多了些，不礙事，反正當天會講解

GNU Bison 與 GPL 授權的適用範疇

「如果我使用到 G++ STL，有必要特別加入 GPL 的宣告嗎？」

// Standard iostream objects -*- C++ -*-
                                                                                
// Copyright (C) 1997, 1998, 1999, 2001, 2002, 2005
// Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library.  This library is free
// software; you can redistribute it and/or modify it under the
// terms of the GNU General Public License as published by the
// Free Software Foundation; either version 2, or (at your option)
// any later version.
[... 略，談及 GPL 與 FSF 的聯絡資訊 ...]

// As a special exception, you may use this file as part of a free software
// library without restriction.  Specifically, if other files instantiate
// templates or use macros or inline functions from this file, or you compile
// this file and link it with other files to produce an executable, this
// file does not by itself cause the resulting executable to be covered by
// the GNU General Public License.  This exception does not however
// invalidate any other reasons why the executable file might be covered by
// the GNU General Public License.

• GNU GCC 的開發者簽署 Copyright Assignment，將著作權歸屬一致給予 FSF，且 STL 實做的著作權聲明標示從 1997 年到 2005 年
• g++ 的 STL 實做以 GNU GPLv2 with exceptions 模式發行
• GPLv2 的額外例外條款描述了使用 STL 的合理範疇，規範編譯、連結，與執行的行為，避免原本 GPLv2 對此語焉不詳的模糊

/* Skeleton implementation for Bison's Yacc-like parsers in C

   Copyright (C) 1984, 1989, 1990, 2000, 2001, 2002, 2003, 2004, 2005, 2006
   Free Software Foundation, Inc.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2, or (at your option)
   any later version.  (...省略，同樣是 FSF 聯絡資訊) */

/* As a special exception, you may create a larger work that contains
   part or all of the Bison parser skeleton and distribute that work
   under terms of your choice, so long as that work isn't itself a
   parser generator using the skeleton or a modified version thereof
   as a parser skeleton.  Alternatively, if you modify or redistribute
   the parser skeleton itself, you may (at your option) remove this
   special exception, which will cause the skeleton and the resulting
   Bison output files to be licensed under the GNU General Public
   License without this special exception.

   This special exception was added by the Free Software Foundation in
   version 2.2 of Bison.  */

• GNU bison 輸出的分析器程式碼，就是貨真價實的 GPL'd 程式，所以會隨著編譯環境 (build system) 整合到我們的專案中，這是顯性的 GPL 感染
• FSF 提出的例外條款聲明，只要不修改 GNU bison 輸出的程式碼 (術語為 "Bison parser skeleton")，單純就當作中間輸出碼一般處理，那麼，可依據任何偏好的授權去套用於我們的專案，當然，包含商業化軟體
• 但若修改或重新散佈 Bison parser skeleton 時，FSF 也允許移除前一條的例外條款，使其成為純粹以 GNU GPL 發行的程式碼

演講：我是軟體 -- 那些處理器教我的事 (COSCUP)

「我好天真，現在才看清，其實這一切並非只是 cross compilation 這麼單純」

《Qtopia 编程之道》即將出版

• Linux 基礎
• 移動終端基礎
• Qtopia 基礎
• Qtopia 核心技術
• 編譯與配置
• C/S 模型
• 風格與主題
• 安裝與整合
• 人機互動
• Qtopia 設計
• 書籍簡介
• 參考文獻

透過虛擬化技術體驗 kgdb (1)

"because people have tried to get me to merge it for some long is kgdb support. Which really turned out pretty small and clean, once people started putting their effort into making it so."

$ tar jxvf linux-2.6.26.tar.bz2
$ cd linux-2.6.26

• CONFIG_DEBUG_INFO=y
• CONFIG_KGDB=y
• CONFIG_KGDB_SERIAL_CONSOLE=y

$ make bzImage

$ sudo apt-get install bridge-utils uml-utilities vtun

#!/bin/bash-x

# id of the user running qemu (kvm). Make sure you change it appropriately.
USERID=1000

# number of TUN/TAP devices to setup
NUM_OF_DEVICES=1

case $1 in
start)
        modprobe tun
        /etc/init.d/vtun start
        chmod a+rw /dev/net/tun
        echo -n "Setting up bridge device br0"
        brctl addbr br0
        ifconfig br0 192.168.99.1 netmask 255.255.255.0 up
        for ((i=0; i < NUM_OF_DEVICES ; i++)); do
                echo -n "Setting up "
                tunctl -b -u $USERID -t qtap$i
                brctl addif br0 qtap$i
                ifconfig qtap$i up 0.0.0.0 promisc
        done
        ;;
stop)
        for ((i=0; i < NUM_OF_DEVICES ; i++)); do
                ifconfig qtap$i down
                brctl delif br0 qtap$i
                tunctl -d qtap$i
        done
        ifconfig br0 down
        brctl delbr br0
        /etc/init.d/vtun stop
        ;;
*)
        echo "Usage: $(basename $0) (start|stop)"
        ;;
esac

# /etc/init.d/kvm-network stop
# /etc/init.d/kvm-network start

qemu -kernel arch/i386/boot/bzImage \
     -hda /dev/zero \
     -net nic -net tap,ifname=qtap0,script=no

# ifconfig eth0 192.168.99.2/24
# route add default gw 192.168.99.1 eth0
# ping -c 5 192.168.99.1

$ qemu \
	-no-acpi \
	-kernel arch/i386/boot/bzImage -hda /dev/zero \
	-net nic \
	-net tap,ifname=qtap0,script=no \
	-serial "stdio" -serial "pty" \
	-append '$console kgdbwait kgdboc=ttyS1'

	-serial "stdio" -serial "pty"

-serial dev

Redirect the virtual serial port to host character device dev. The default device is "vc" in graphical mode and "stdio" in non graphical mode. This option can be used several times to simulate up to 4 serials ports.

	-append '$console kgdbwait kgdboc=ttyS1'

kgdb: Registered I/O driver kgdboc...
kgdb: Waiting for connection from remote gdb...

$ ls -lh arch/x86/boot/bzImage vmlinux
-rw-r--r-- 1 jserv jserv 1.6M 2008-06-02 01:37 arch/x86/boot/bzImage
-rwxr-xr-x 1 jserv jserv  21M 2008-06-02 01:37 vmlinux

$ gdb ./vmlinux
GNU gdb 6.8-debian
Copyright (C) 2008 Free Software Foundation, Inc.
[...]
This GDB was configured as "i486-linux-gnu"...
(gdb) shell echo -e "\003" > /dev/ttyp9
(gdb) set remotebaud 115200
(gdb) target remote /dev/ttyp9
Remote debugging using /dev/ttyp9
kgdb_register_io_module (new_kgdb_io_ops=0xc028f914) at kernel/kgdb.c:1677
1677		wmb(); /* Sync point after breakpoint */
(gdb) 

(gdb) target remote /dev/ttyp9

(gdb) list
1672	void kgdb_breakpoint(void)
1673	{
1674		atomic_set(&kgdb_setting_breakpoint, 1);
1675		wmb(); /* Sync point before breakpoint */
1676		arch_kgdb_breakpoint();
1677		wmb(); /* Sync point after breakpoint */
1678		atomic_set(&kgdb_setting_breakpoint, 0);
1679	}
1680	EXPORT_SYMBOL_GPL(kgdb_breakpoint);
1681	
(gdb)

(gdb) n
[New Thread 1]
1678		atomic_set(&kgdb_setting_breakpoint, 0);
(gdb) n
1632	}

(gdb) p jiffies
$1 = -74817
(gdb) p jiffies_64
$2 = 4294892479
(gdb)

上衣口袋夾帶原子筆的故事

「快快樂樂學 GNU Debugger (gdb) Part I + II」簡報上線

• Part I 簡報：[HappyGDB-PartI-2008-07-12.pdf]，範例檔案：[samples1-2008-07-12.tar.bz2]
• Part II 簡報：[HappyGDB-PartII-2008-07-12.pdf]，範例檔案：[samples2-2008-07-12.tar.bz2]

不再囉唆：NetBSD 簡化 BSD 授權條款

• Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
• Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.
• All advertising materials mentioning features or use of this software must display the following acknowledgement: This product includes software developed by the University of California, Berkeley and its contributors.
• Neither the name of the University nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission.

• 規範以原始程式碼形式的再散播，需保有同樣的授權聲明
• 要求二進位可執行形式的再散播，需在檔案或所屬的媒介中，附上授權、免責條款等資訊
• 軟體本身應提供如廣告般的機制，附帶提及告知研發軟體的加州大學
• 未獲得許可前，禁止以原作者或加州大學之名，行衍生軟體之背書、推廣、促銷等行為

"All advertising materials mentioning features or use of this software must display the following acknowledgement: This product includes software developed by the University of California, Berkeley and its contributors."

• NetBSD 仍使用原始的 BSD 授權條款 (4-clause)
• FreeBSD 使用兩句版授權條款 (2-clause)，另行於末尾添加非 FreeBSD 基金會的貢獻者列表
• DragonFlyBSD 使用 3-clause/new- BSD 授權條款，與 FreeBSD 4 分家前同
• OpenBSD 對所有添加的軟體，採用 Internet Systems Consortium, Inc 的版權條款，就其功能 來說，也就是 2-clause BSD 授權

"Neither the name of the University nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission."

• we have seen organisations and people concerned about the old clause 3 (the advertising clause) in the license, to the extent where NetBSD code could not be used in commercial products; the new license means that these concerns are no longer valid
• UCB moved some time ago to remove clause 3 from the code contributed to UCB; this change mirrors that one
• we have seen some instances where clause 3 was ignored by groups and organisations
• the members of the NetBSD Foundation (i.e. its developers) no longer considered clause 4 (the "endorsement" clause) to be useful in today's software world

取得 GNU/Linux 行程的執行檔路徑

「取得 Linux 行程的執行檔路徑，有什麼好處？在什麼場合需要？」

int main(int argc ATTRIBUTE_UNUSED, char **argv)
{
	applet_name = argv[0];
	if (applet_name[0] == '-')
		applet_name++;
	applet_name = bb_basename(applet_name);

	parse_config_file(); /* ...maybe, if FEATURE_SUID_CONFIG */

	run_applet_and_exit(applet_name, argv);

	/*bb_error_msg_and_die("applet not found"); - sucks in printf */
	full_write2_str(applet_name);
	full_write2_str(": applet not found\n");
	xfunc_die();
}

void FAST_FUNC run_applet_and_exit(const char *name, char **argv)
{
	int applet = find_applet_by_name(name);                                 
	if (applet >= 0)
		run_applet_no_and_exit(applet, argv);
	if (!strncmp(name, "busybox", 7))
		exit(busybox_main(argv));
}

int FAST_FUNC find_applet_by_name(const char *name)
{
	/* Do a binary search to find the applet entry given the name. */

	const char *p;
	p = bsearch(name, applet_names, ARRAY_SIZE(applet_main), 1, applet_name_compare);
	if (!p)
		return -1;
	return p - applet_names;
}

• 絕對路徑：基本上只要去除多餘的字串表示，如 "//"，即可使用
• 相對路徑：需要配合目前執行程式的路徑，在檔案系統中，找出最終的絕對路徑
• 只有程式名稱、沒有路徑：因為 shell 透過 $PATH 環境變數找到程式，但 argv[0] 接收時僅有名稱，這時候，得循序依 $PATH 字串內容，逐一於檔案系統中找到程式的絕對路徑
• 其他：當透過 exec 系列的系統呼叫時，什麼名稱都有可能，端視呼叫的形式，這時候就得找出方法 (沒有一定準則)

# ls -l /proc/1/exe
lrwxrwxrwx 1 root root 0 2008-07-03 22:10 /proc/1/exe -> /sbin/init

#include <sys/types.h>
#include <unistd.h>

#define MSG_1 "child ends.\n"
#define MSG_2 "parent about to fork self.\n"
extern char **environ;
int main(int argc, char *argv[])
{
	char *fn[] = { "/proc/self/exe", 0 };
	pid_t pid = fork();
	if (0 == pid) {
		write(1, MSG_1, sizeof(MSG_1));
	}
	else if (-1 == pid) { /* unable to fork */
		_exit(-1);
	}
	else {
		write(1, MSG_2, sizeof(MSG_2));
		execve(*fn, fn, environ);
	}
	return 0;
}

• "/proc/self/exe" 與 exec 函式的搭配
• fork() 後，我們試著 exec "/proc/self/exe"，也就是本行程對應的執行檔名，以取代 parent process
• 由於重複該動作，fork() 可能會失敗，務必作確認與例外情況處理 (_exit)

$ gcc -o fork-self fork-self.c
$ ./fork-self
child ends.
parent about to fork self.
child ends.
parent about to fork self.
child ends.
parent about to fork self.
... (重複) ...

init-+-NetworkManager---{NetworkManager}
     |-NetworkManagerD
     |-acpid
	...
     |-rxvt-unicode--bash---exe-+-11599*[exe]
     |                          `-fork-self
	...

推薦「E-GI建築師事務所實習報告」

喜歡畫畫，但是不是藝術家。
喜歡發呆，但是腦袋總塞爆想法。
喜歡，一切。

觀察 Linux 的虛擬記憶體

$ vmstat -S m
procs -----------memory---------- ---swap-- -----io---- -system-- ----cpu----
 r  b   swpd   free   buff  cache   si   so    bi    bo   in   cs us sy id wa
 1  0      0     81    110    895    0    0    11    36  160  161 62 17 21  1

$ watch  cat /proc/meminfo

httping : 針對 HTTP Request 的仿 ping 程式

Give it an url, and it'll show you how long it takes to connect, send a request and retrieve the reply (only the headers). Be aware that the transmission across the network also takes time!

$ httping -g http://www.google.com -c 5
PING www.google.com:80 (http://www.google.com):
connected to www.google.com:80, seq=0 time=641.30 ms 
connected to www.google.com:80, seq=1 time=672.34 ms 
connected to www.google.com:80, seq=2 time=692.74 ms 
connected to www.google.com:80, seq=3 time=660.11 ms 
connected to www.google.com:80, seq=4 time=654.99 ms 
--- http://www.google.com ping statistics ---
5 connects, 5 ok, 0.00% failed
round-trip min/avg/max = 641.3/664.3/692.7 ms

$ ping www.google.com -c 5
PING www.l.google.com (74.125.19.104) 56(84) bytes of data.
64 bytes from cf-in-f104.google.com (74.125.19.104): icmp_seq=1 ttl=241 time=258 ms
64 bytes from cf-in-f104.google.com (74.125.19.104): icmp_seq=2 ttl=241 time=258 ms
64 bytes from cf-in-f104.google.com (74.125.19.104): icmp_seq=3 ttl=241 time=257 ms
64 bytes from cf-in-f104.google.com (74.125.19.104): icmp_seq=4 ttl=241 time=257 ms

--- www.l.google.com ping statistics ---
5 packets transmitted, 4 received, 20% packet loss, time 4019ms
rtt min/avg/max/mdev = 257.860/258.053/258.395/0.656 ms

演講：快快樂樂學 GNU Debugger (gdb) Part I + II [台中]

• 簡介：期望使聽者得以透過 GNU Debugger (gdb) 來加速系統開發與分析，讓這個臥在硬碟深處許久的強力程式，激發其威力。本議程捨棄過往教條式的介紹形式，延續「深入淺出 HelloWorld」系列的「作中學」途徑逐一探討使用情境與案例分析
• 議程主題：
  • Why - 為何我們該善用 Debugger？
  • Who - 誰會因為熟悉 Debugger 而受益？
  • What - 史上最強大的 Debugger -- gdb 與一系列系統軟體
  • Where - 利用 Debugger 的場合
  • How - 還用說嗎？來就對了！
• 涵蓋項目：
  • 實用 GDB 指令
  • macro 與技巧
  • 當 GDB 遇上 C/C++：具體的範例
• 參考資訊：
  • 簡報與範例檔案： http://jserv.sayya.org/debugger/
  • GNU Debugger: http://sourceware.org/gdb/
• 時間：七月 12 日 10:00-12:00 (Part I), 13:30-17:00 (Part II)
• 地點：亞洲大學 (台中縣霧峰鄉柳豐路500號) 管理大樓 B1 M009 教室
• 費用： 0 –
• 人數限制：無限制
• 報名網站：http://registrano.com/events/sataichung080712
• 交通： 自行開車； 搭乘客運或公車至台中火車站--前站（建國路）對面搭乘100號公車往省諮議會方向--最後一站 亞洲大學