#include <unistd.h>
#include <stdio.h>
#include <fcntl.h>
#include <linux/fb.h> // include frame buffer header files
#include <sys/ioctl.h>
int main(void)
{
int fbfd = 0 ; // frame buffer file description
/* Get device independent unchangeable information about a frame buffer
* device and a specific video mode by FBIOGET_FSCREENINFO ioctl. */
struct fb_fix_screeninfo finfo;
fbfd = open( "/dev/fb0" , O_RDWR );
if ( !fbfd )
{
printf( "Error: cannot open framebuffer device.\n" );
exit(1);
}
printf("The framebuffer device was opened successfully.\n");
/* Get fixed screen information */
if ( ioctl ( fbfd , FBIOGET_FSCREENINFO , &finfo ) )
{
printf("Error reading fixed screen information.\n");
exit(2);
} else {
printf("Succesfully Read the Fixed Screen Information\n");
}
printf("fb_fix_screeninfo.smem_len = %d\n", finfo.smem_len);
printf("fb_fix_screeninfo.mmio_len = %d\n", finfo.mmio_len);
}
- 在 Ubuntu Intrepid 上執行結果
root@intrepid:~# uname -a
Linux intrepid 2.6.27-7-server #1 SMP Tue Nov 4 20:16:57 UTC 2008 x86_64 GNU/Linux
root@intrepid:~# ./fbinfo
The framebuffer device was opened successfully.
Succesfully Read the Fixed Screen Information
fb_fix_screeninfo.smem_len = 16777216
fb_fix_screeninfo.mmio_len = 0
- 以下是在 Debian Sarge 上執行結果，值得一提的是 jfbterm 在 2.6.8 核心上可以正常執行。(不過還有字型問題需要調整)
root@wsu-admin:~# uname -a
Linux wsu-admin 2.6.8-2-386 #1 Tue Aug 16 12:46:35 UTC 2005 i686 GNU/Linux
root@wsu-admin:~# ./fbinfo
The framebuffer device was opened successfully.
Succesfully Read the Fixed Screen Information
fb_fix_screeninfo.smem_len = 65536
fb_fix_screeninfo.mmio_len = 0
root@wsu-admin:~# jfbterm
jfbterm - Kanji on framebuffer console Version 0.4.7
Copyright (C) 2003 Fumitoshi UKAI
Copyright (C) 1999-2000 Noritoshi Masuichi
This program is based on KON2
Copyright (C) 1992-1996 Takashi MANABE
(**) : Configuration file `/etc/jfbterm.conf'
.... 略 ....
exec : /bin/bash ioctl FBIOGET_CON2FBMAP: Invalid argument
color 0 : 0, 0
color 1 : 2a, 2a
color 2 : 2a, 2a
color 3 : 2a, 2a
color 4 : 2a, 2a
color 5 : 2a, 2a
color 6 : 2a, 2a
color 7 : 2a, 2a
color 8 : 15, 15
color 9 : 3f, 3f
color 10 : 3f, 3f
color 11 : 3f, 3f
color 12 : 3f, 3f
color 13 : 3f, 3f
color 14 : 3f, 3f
color 15 : 3f, 3f
- 以下是在 Debian Etch 上執行結果，有趣的是 jfbterm 0.4.7-7 在 2.6.18-4 上執行，縱使有 cannot mmap(mmio) : Invalid argument 的錯誤訊息，但仍舊可以正常進入 jfbterm 的環境。
root@etch:~# uname -a
Linux etch 2.6.18-4-686 #1 SMP Wed May 9 23:03:12 UTC 2007 i686 GNU/Linux
root@etch:~# ./fbinfo
The framebuffer device was opened successfully.
Succesfully Read the Fixed Screen Information
fb_fix_screeninfo.smem_len = 1920000
fb_fix_screeninfo.mmio_len = 0
root@etch:~# jfbterm
jfbterm - Kanji on framebuffer console Version 0.4.7
Copyright (C) 2003 Fumitoshi UKAI
Copyright (C) 1999-2000 Noritoshi Masuichi
This program is based on KON2
Copyright (C) 1992-1996 Takashi MANABE
(**) : Configuration file `/etc/jfbterm.conf'
... 略 ...
exec : /bin/bash color 0 : 0, 0
color 1 : 15, 15
color 2 : 540, 540
color 3 : 555, 555
color 4 : a800, a800
color 5 : a815, a815
color 6 : ad40, ad40
color 7 : ad55, ad55
color 8 : 52aa, 52aa
color 9 : 52bf, 52bf
color 10 : 57ea, 57ea
color 11 : 57ff, 57ff
color 12 : faaa, faaa
color 13 : fabf, fabf
color 14 : ffea, ffea
color 15 : ffff, ffff
cannot mmap(mmio) : Invalid argument
- 為了測試 jfbterm 的中文相容性，我們寫了一隻簡單的 script
#!/bin/bash
echo " TEST 中文測試 "
echo "Press Any Key to continue!"
read
- 在 Ubutnu intriped 的 tty1 上執行 jfbterm -f /etc/jfbterm.conf -e /root/test.sh 可以正常看到" TEST 中文測試 "字樣，但卻無法正常跳出，因此我們再來 DEBUG 一下。
file jfbterm
set args -f /etc/jfbterm.conf -e /root/test.sh
show args
break fbcommon.c:500
break fbcommon.c:557
break fbcommon.c:566
break term.c:103
break term.c:284
r
c
c
c
bt
c
bt
p utp->ut_time
p utp->ut_tv
Breakpoint 4, tterm_final (p=0x6147c0) at term.c:103
(gdb) bt
#0 tterm_final (p=0x6147c0) at term.c:103
#1 0x0000000000408adf in sigchld (sig=<value optimized out>) at term.c:82
#2 <signal handler called>
#3 0x00007f5dfc00f433 in select () from /lib/libc.so.6
#4 0x0000000000408873 in tterm_start (p=0x6147c0, tn=<value optimized out>, en=<value optimized out>) at term.c:192
#5 0x0000000000402cf2 in main (argc=<value optimized out>, argv=0x7fff049477f8) at main.c:438
(gdb) c
Continuing.
Breakpoint 5, tterm_reset_utmp (p=<value optimized out>) at term.c:284
(gdb) bt
#0 tterm_reset_utmp (p=<value optimized out>) at term.c:284
#1 0x0000000000408a50 in tterm_final (p=0xe) at term.c:103
#2 0x0000000000408adf in sigchld (sig=<value optimized out>) at term.c:82
#3 <signal handler called>
#4 0x00007fa268131433 in select () from /lib/libc.so.6
#5 0x0000000000408873 in tterm_start (p=0x6147c0, tn=<value optimized out>, en=<value optimized out>) at term.c:192
#6 0x0000000000402cf2 in main (argc=<value optimized out>, argv=0x7fff70a69328) at main.c:438
(gdb) p utp->ut_time
There is no member named ut_time.
- [註] utp->ut_time = utp->ut_tv.tv_sec
< /usr/include/bits/utmp.h >
59 /* The structure describing an entry in the user accounting database. */
60 struct utmp
61 {
62 short int ut_type; /* Type of login. */
63 pid_t ut_pid; /* Process ID of login process. */
64 char ut_line[UT_LINESIZE]; /* Devicename. */
65 char ut_id[4]; /* Inittab ID. */
66 char ut_user[UT_NAMESIZE]; /* Username. */
67 char ut_host[UT_HOSTSIZE]; /* Hostname for remote login. */
68 struct exit_status ut_exit; /* Exit status of a process marked
69 as DEAD_PROCESS. */
70 /* The ut_session and ut_tv fields must be the same size when compiled
71 32- and 64-bit. This allows data files and shared memory to be
72 shared between 32- and 64-bit applications. */
73 #if __WORDSIZE == 64 && defined __WORDSIZE_COMPAT32
74 int32_t ut_session; /* Session ID, used for windowing. */
75 struct
76 {
77 int32_t tv_sec; /* Seconds. */
78 int32_t tv_usec; /* Microseconds. */
79 } ut_tv; /* Time entry was made. */
80 #else
81 long int ut_session; /* Session ID, used for windowing. */
82 struct timeval ut_tv; /* Time entry was made. */
83 #endif
84
85 int32_t ut_addr_v6[4]; /* Internet address of remote host. */
86 char __unused[20]; /* Reserved for future use. */
87 };
94 # define ut_time ut_tv.tv_sec
- GDB 線上除錯練習
[tty1]
root@etch:~# apt-get build-dep jfbterm
root@etch:~# apt-get source jfbterm
root@etch:~# apt-get install jfbterm
root@etch:~# cd jfbterm-0.4.7
root@etch:~/jfbterm-0.4.7# ./configure --enable-debug
root@etch:~/jfbterm-0.4.7# make
root@etch:~/jfbterm-0.4.7# ./jfbterm -f /etc/jfbterm.conf -e /root/test.sh
[tty2]
root@etch:~# gdb /root/jfbterm-0.4.7/jfbterm `pidof jfbterm`
GNU gdb 6.4.90-debian
Copyright (C) 2006 Free Software Foundation, Inc.
GDB is free software, covered by the GNU General Public License, and you are
welcome to change it and/or distribute copies of it under certain conditions.
Type "show copying" to see the conditions.
There is absolutely no warranty for GDB. Type "show warranty" for details.
This GDB was configured as "i486-linux-gnu"...Using host libthread_db library "/lib/tls/i686/cmov/libthread_db.so.1".
Attaching to program: /root/jfbterm-0.4.7/jfbterm, process 7480
Reading symbols from /lib/tls/i686/cmov/libutil.so.1...done.
Loaded symbols for /lib/tls/i686/cmov/libutil.so.1
Reading symbols from /lib/tls/i686/cmov/libm.so.6...done.
Loaded symbols for /lib/tls/i686/cmov/libm.so.6
Reading symbols from /lib/tls/i686/cmov/libc.so.6...done.
Loaded symbols for /lib/tls/i686/cmov/libc.so.6
Reading symbols from /lib/ld-linux.so.2...done.
Loaded symbols for /lib/ld-linux.so.2
Reading symbols from /lib/tls/i686/cmov/libnss_compat.so.2...done.
Loaded symbols for /lib/tls/i686/cmov/libnss_compat.so.2
Reading symbols from /lib/tls/i686/cmov/libnsl.so.1...done.
Loaded symbols for /lib/tls/i686/cmov/libnsl.so.1
Reading symbols from /lib/tls/i686/cmov/libnss_nis.so.2...done.
Loaded symbols for /lib/tls/i686/cmov/libnss_nis.so.2
Reading symbols from /lib/tls/i686/cmov/libnss_files.so.2...done.
Loaded symbols for /lib/tls/i686/cmov/libnss_files.so.2
Failed to read a valid object file image from memory.
0xb7fea410 in ?? ()
(gdb) break term.c:284
Breakpoint 1 at 0x804f552: file term.c, line 284.
(gdb) c
Continuing.
Breakpoint 1, tterm_final (p=0x8058be0) at term.c:284
284 time(&(utp->ut_time));
(gdb) c
Continuing.
Breakpoint 1, tterm_final (p=0x8058be0) at term.c:284
284 time(&(utp->ut_time));
(gdb) c
Continuing.
Program exited normally.
- GDB 遠端除錯練習
[tty1]
gdbserver 127.0.0.1:1234 /root/jfbterm-0.4.7/jfbterm
[pts1]
(gdb) target remote 127.0.0.1:1234
- 在 DEBUG 的時候偶爾會看到 <value optimized out>，但是該怎麼去掉呢??
- [參考] http://www.cs.utk.edu/~vose/c-stuff/onlinedocs/gdb_7.html
The values of arguments that were not saved in their stack frames are shown as `<value optimized out>'.
If you need to display the values of such optimized-out arguments, either deduce that from other variables whose values depend on the one you are interested in, or recompile without optimizations.
- [作法] 在 configure 的時候加上 CFLAGS
- 繼續追為何結束時會收到 SIGSEGV 的主因
< 直接在 tty1 或在 screen 中執行 >
root@intrepid:~/jfbterm-0.4.7-dev# ./jfbterm -f /etc/jfbterm.conf -e /root/test.sh
root@intrepid:~/jfbterm-0.4.7-dev# gdb ./jfbterm `pidof jfbterm`
break term.c:103
break term.c:284
c
#### 直接在 tty1 不透過 screen 執行 的結果 #####
Breakpoint 1, tterm_final (p=0x617a00) at term.c:103
103 tterm_reset_utmp(p);
(gdb) s
tterm_reset_utmp (p=0x617a00) at term.c:271
271 {
(gdb) s
275 tn = rindex(p->name, '/') + 4;
(gdb) p p->name
$1 = "/dev/pts/0", '\0' <repeats 53 times>
#### 直接在 tty1 有透過 screen 執行 的結果 #####
Breakpoint 1, tterm_final (p=0x617a00) at term.c:103
103 tterm_reset_utmp(p);
(gdb) s
tterm_reset_utmp (p=0x617a00) at term.c:271
271 {
(gdb) s
275 tn = rindex(p->name, '/') + 4;
(gdb) p p->name
$1 = "/dev/pts/1", '\0' <repeats 53 times>
- manpage of getutid(3)
SYNOPSIS
struct utmp *getutid(struct utmp *ut);
DESCRIPTION
getutid() searches forward from the current file position in the utmp
file based upon ut. If ut->ut_type is one of RUN_LVL, BOOT_TIME,
NEW_TIME, or OLD_TIME, getutid() will find the first entry whose
ut_type field matches ut->ut_type. If ut->ut_type is one of INIT_PRO-
CESS, LOGIN_PROCESS, USER_PROCESS, or DEAD_PROCESS, getutid() will find
the first entry whose ut_id field matches ut->ut_id.
root@intrepid:~# w
02:01:29 up 5 min, 5 users, load average: 0.75, 0.91, 0.41
USER TTY FROM LOGIN@ IDLE JCPU PCPU WHAT
root@intrepid:~# w
02:02:14 up 6 min, 5 users, load average: 0.35, 0.78, 0.39
USER TTY FROM LOGIN@ IDLE JCPU PCPU WHAT
root pts/0 :tty1:S.0 01:58 1:46m 0.24s 0.21s ./jfbterm -f /etc/jfbterm.conf -e /root/test.sh ### screen 0
root pts/1 :tty1:S.1 01:58 3:55m 0.01s 0.01s /bin/bash ### screen 1
root pts/3 172.21.253.1 01:59 1:19m 0.12s 0.10s gdb ./jfbterm 3833 ### from ssh for gdb
root pts/2 - 01:59 1:46m 0.00s 0.21s ./jfbterm -f /etc/jfbterm.conf -e /root/test.sh ### fb created by jfbterm
root pts/4 172.21.253.1 02:01 0.00s 0.02s 0.00s w ### from ssh for this command `w'
