- [DRBL] jfbterm Bug
- [備註] 如果沒有 modprobe uvesafb 的話，會缺少 /dev/fb0，因此當執行 jfbterm 時就會出現以下錯誤訊息
ENCODING: locale = UTF-8
FONT : (4) [iso10646.1]/pcf/U:///usr/share/fonts/X11/misc/unifont.pcf.gz/
encoding : UTF-8,iso10646.1
exec : ls open /dev/fb0: No such file or directory
- [備註] 如果沒有裝 v86d 的話，當執行 modprobe uvesafb 時會在 dmesg 看到以下資訊
[ 703.839376] uvesafb: failed to execute /sbin/v86d
[ 703.840224] uvesafb: make sure that the v86d helper is installed and executable
[ 703.841494] uvesafb: Getting VBE info block failed (eax=0x4f00, err=-2)
[ 703.842307] uvesafb: vbe_init() failed with -22
[ 703.843019] uvesafb: probe of uvesafb.0 failed with error -22
- [備註] 如果有裝 v86d 的話，當執行 modprobe uvesafb 時會在 dmesg 看到以下資訊
[ 268.848377] uvesafb: VMware, IncVMware virtual machine2.0, VMware virtual machine2.0, 2.0, OEM: V M ware, Inc. VBE support 2.0VMware, IncVMware virtual machine2.0, VBE v2.0
[ 268.884099] uvesafb: no monitor limits have been set, default refresh rate will be used
[ 268.885202] uvesafb: VBE state buffer size cannot be determined (eax=0x0, err=0)
[ 268.885265] uvesafb: scrolling: redraw
[ 268.896617] mtrr: your processor doesn't support write-combining
[ 268.909303] Console: switching to colour frame buffer device 128x48
[ 269.938085] uvesafb: framebuffer at 0xf0000000, mapped to 0xffffc20000180000, using 16384k, total 16384k
[ 269.938101] fb0: VESA VGA frame buffer device
- 編輯 GRUB 的 menu.lst 就可以不用每次都跑 modprobe
-
|
old
|
new
|
|
| 125 | 125 | |
| 126 | 126 | title Ubuntu 8.10, kernel 2.6.27-7-server |
| 127 | 127 | uuid 574912ac-8bd6-4cc7-90c6-8c5362033fec |
| 128 | | kernel /boot/vmlinuz-2.6.27-7-server root=UUID=574912ac-8bd6-4cc7-90c6-8c5362033fec ro quiet splash |
| | 128 | kernel /boot/vmlinuz-2.6.27-7-server root=UUID=574912ac-8bd6-4cc7-90c6-8c5362033fec ro quiet splash vga=0x305 |
| 129 | 129 | initrd /boot/initrd.img-2.6.27-7-server |
| 130 | 130 | quiet |
- 用 modinfo 觀看 Ubuntu 8.10 Kernel 2.6.27-7-server 的 uvesafb 模組參數，發現包括 scroll、vgapal、pmipal、mtrr、blank、nocrtc、noedid、vram_remap、vram_total、maxclk、maxhf、maxvf、mode_option、vbemode、v86d。並沒有 mode 這個參數。
root@intrepid:~# modinfo uvesafb
filename: /lib/modules/2.6.27-7-server/kernel/drivers/video/uvesafb.ko
description: Framebuffer driver for VBE2.0+ compliant graphics boards
author: Michal Januszewski <spock@gentoo.org>
license: GPL
srcversion: 21EDEFDED06E0673208A0D5
depends:
vermagic: 2.6.27-7-server SMP mod_unload modversions
parm: scroll:Scrolling mode, set to 'redraw', 'ypan', or 'ywrap' (scroll)
parm: vgapal:Set palette using VGA registers (invbool)
parm: pmipal:Set palette using PMI calls (bool)
parm: mtrr:Memory Type Range Registers setting. Use 0 to disable. (uint)
parm: blank:Enable hardware blanking (bool)
parm: nocrtc:Ignore CRTC timings when setting modes (bool)
parm: noedid:Ignore EDID-provided monitor limits when setting modes (bool)
parm: vram_remap:Set amount of video memory to be used [MiB] (uint)
parm: vram_total:Set total amount of video memoery [MiB] (uint)
parm: maxclk:Maximum pixelclock [MHz], overrides EDID data (ushort)
parm: maxhf:Maximum horizontal frequency [kHz], overrides EDID data (ushort)
parm: maxvf:Maximum vertical frequency [Hz], overrides EDID data (ushort)
parm: mode_option:Specify initial video mode as "<xres>x<yres>[-<bpp>][@<refresh>]" (charp)
parm: vbemode:VBE mode number to set, overrides the 'mode' option (ushort)
parm: v86d:Path to the v86d userspace helper. (string)
root@intrepid:~# LANG=C apt-cache policy v86d
v86d:
Installed: 0.1.5-1ubuntu2
Candidate: 0.1.5-1ubuntu2
Version table:
*** 0.1.5-1ubuntu2 0
500 http://tw.archive.ubuntu.com intrepid/universe Packages
100 /var/lib/dpkg/status
root@intrepid:~# LANG=C apt-cache policy jfbterm
jfbterm:
Installed: 0.4.7-7.2
Candidate: 0.4.7-7.2
Version table:
*** 0.4.7-7.2 0
500 http://tw.archive.ubuntu.com intrepid/universe Packages
100 /var/lib/dpkg/status
- 追蹤 jfbterm 的 deb package 原始碼
root@intrepid:~# apt-get build-dep jfbterm
root@intrepid:~# apt-get install dpkg-dev
root@intrepid:~# apt-get source jfbterm
- uvesafb 作者的推測:
As to why the console becomes unresponsive after exiting jfbterm --
jfbterm sets KD_GRAPHICS mode on the console on which it is started,
and apparently fails to set it back to KD_TEXT before segfaulting. This
leaves the console in the broken state.
- 尋找合理懷疑對象(1):
root@intrepid:~/jfbterm-0.4.7# grep "KD_GRAPHICS" *
vterm.c: ioctl(0, KDSETMODE, KD_GRAPHICS);
root@intrepid:~/jfbterm-0.4.7# grep "KD_TEXT" *
main.c: if (mode == KD_TEXT) {
vterm.c: ioctl(0, KDSETMODE, KD_TEXT);
- 尋找合理懷疑對象(2):
root@intrepid:~/jfbterm-0.4.7# grep "cannot mmap" *
fbcommon.c: die("cannot mmap(smem)");
fbcommon.c: die("cannot mmap(mmio)");
fbcommon.c: print_message("cannot mmap(mmio) : %s\n", strerror(errno));
- 啟用 DEBUG 旗標，編譯 jfbterm，使用 gdb 追蹤
root@intrepid:~/jfbterm-0.4.7# ./configure --enable-debug
root@intrepid:~/jfbterm-0.4.7# make
root@intrepid:~/jfbterm-0.4.7# gdb ./jfbterm
(gdb) run
- 縱使用 gdb 還是無法正常跳回文字模式，因此直接追原始碼。
- [後記] uvesafb 作者的猜測確實合理，因為已經進入圖形模式，除非跳回文字模式，否則所有輸入輸出都不會正常顯示在畫面上。
- 根據錯誤訊息,應該是錯在 fbcommon.c 的第 572 行，往前追造成錯誤的原因是 566 行的 mmap()，歸屬在 tfbm_open() 函數
< fbcommon.c >
482 void tfbm_open(TFrameBufferMemory* p)
566 p->mmio = (u_char*)mmap(NULL, p->mlen, PROT_READ|PROT_WRITE,
567 MAP_SHARED, p->fh, p->slen);
568 if ((long)p->mmio == -1) {
569 #ifdef JFB_MMIO_CHECK
570 die("cannot mmap(mmio)");
571 #else
572 print_message("cannot mmap(mmio) : %s\n", strerror(errno));
573 #endif
< main.c >
368 int main(int argc, char *argv[])
431 tfbm_open(&gFramebuffer);
- 安裝 manpages-dev 套件，查 mmap 、 strerror 跟 errno 的 manpage。從 cannot mmap(mmio) : Invalid argument 這個錯誤訊息可以判斷 errno 等於 EINVAL。而 mmap 發生 EINVAL 的情形有三種，最可能的原因是第一個：We don't like addr, length, or offset (e.g., they are too large, or not aligned on a page boundary).
- 這裡注意到 mmap 的 offset 參數必須是 sysconf 中定義 _SC_PAGE_SIZE 的倍數。(offset must be a multiple of the page size as returned by sysconf(_SC_PAGE_SIZE).)
root@intrepid:~/jfbterm-0.4.7# apt-get install manpages-dev
root@intrepid:~/jfbterm-0.4.7# man errno
EINVAL Invalid argument (POSIX.1)
void *mmap(void *addr, size_t length, int prot, int flags, int fd, off_t offset);
offset must be a multiple of the page size as returned by sysconf(_SC_PAGE_SIZE).
ERRORS
EINVAL We don't like addr, length, or offset (e.g., they are too large, or not aligned on a page boundary).
EINVAL (since Linux 2.6.12) length was 0.
EINVAL flags contained neither MAP_PRIVATE or MAP_SHARED, or contained both of these values.
- 使用 gdb 設定中斷點在 fbcomm.c 第 566 行並觀察變數狀態
root@intrepid:~/jfbterm-0.4.7# gdb
(gdb) file jfbterm
Reading symbols from /root/jfbterm-0.4.7/jfbterm...done.
(gdb) set args -e ls
(gdb) show args
Argument list to give program being debugged when it is started is "-e ls".
(gdb) break fbcommon.c:566
Breakpoint 1 at 0x4034ba: file fbcommon.c, line 566.
(gdb) run
... 略 ...
Breakpoint 1, tfbm_open (p=0x6146e0) at fbcommon.c:566
566 p->mmio = (u_char*)mmap(NULL, p->mlen, PROT_READ|PROT_WRITE,
(gdb) l
561 }
562 p->smem = (char *)p->smem + p->soff;
563
564 p->moff = (u_long)(fb_fix.mmio_start) & (~PAGE_MASK);
565 p->mlen = (fb_fix.mmio_len + p->moff + ~PAGE_MASK) & PAGE_MASK;
566 p->mmio = (u_char*)mmap(NULL, p->mlen, PROT_READ|PROT_WRITE,
567 MAP_SHARED, p->fh, p->slen);
568 if ((long)p->mmio == -1) {
569 #ifdef JFB_MMIO_CHECK
570 die("cannot mmap(mmio)");
(gdb) p fb_fix.mmio_len
$1 = 0
(gdb) p p->moff
$2 = 0
(gdb) p p->mlen
$3 = 0
(gdb) p p->fh
$4 = 6
(gdb) p p->slen
$5 = 1572864
(gdb) p fb_fix.smem_len
$6 = 1572864
- 在看 fbcommon.c 時，發現在這組出現錯誤的 mmap 前曾跑過另一組 mmap, 因此把參數印出來對照看看。
- gdb debug 程序
file jfbterm
set args -e ls
show args
break fbcommon.c:500
break fbcommon.c:557
break fbcommon.c:566
run
p fb_fix
c
p fb_fix
c
p fb_fix.smem_len
p p->soff
p p->slen
p fb_fix.mmio_len
p p->moff
p p->mlen
root@intrepid:~/jfbterm-0.4.7-dev# gdb
GNU gdb 6.8-debian
Copyright (C) 2008 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
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 "x86_64-linux-gnu".
(gdb) file jfbterm
Reading symbols from /root/jfbterm-0.4.7-dev/jfbterm...done.
(gdb) set args -e ls
(gdb) show args
Argument list to give program being debugged when it is started is "-e ls".
(gdb) break fbcommon.c:500
Breakpoint 1 at 0x40303d: file fbcommon.c, line 500.
(gdb) break fbcommon.c:557
Breakpoint 2 at 0x40327e: file fbcommon.c, line 557.
(gdb) break fbcommon.c:566
Breakpoint 3 at 0x403301: file fbcommon.c, line 566.
(gdb) run
Starting program: /root/jfbterm-0.4.7-dev/jfbterm -e ls
...略...
Breakpoint 1, tfbm_open (p=0x6146e0) at fbcommon.c:501
501 if (fb_var.yres_virtual != fb_var.yres) {
(gdb) p fb_fix
$1 = {id = "▒\204▒▒Q\177\000\000\006\000\000\000\000\000\000", smem_start = 21037808,
smem_len = 4269392626, type = 32593, type_aux = 0, visual = 0,
xpanstep = 65535, ypanstep = 65535, ywrapstep = 65535, line_length = 1, mmio_start = 15,
mmio_len = 21076240, accel = 0, reserved = {53071, 64, 0}}
(gdb) c
Continuing.
...略...
Breakpoint 2, tfbm_open (p=0x6146e0) at fbcommon.c:557
557 p->smem = (u_char*)mmap(NULL, p->slen, PROT_READ|PROT_WRITE,
(gdb) p fb_fix
$2 = {id = "VESA VGA\000\000\000\000\000\000\000", smem_start = 4026531840,
smem_len = 1572864, type = 0, type_aux = 0, visual = 3, xpanstep = 0,
ypanstep = 0, ywrapstep = 0, line_length = 1024, mmio_start = 0,
mmio_len = 0, accel = 0, reserved = {0, 0, 0}}
(gdb) c
Continuing.
Breakpoint 3, tfbm_open (p=0x6146e0) at fbcommon.c:566
566 if(p->mlen == 0)
(gdb) p fb_fix.smem_len
$3 = 1572864
(gdb) p p->soff
$4 = 0
(gdb) p p->slen
$5 = 1572864
(gdb) p fb_fix.mmio_len
$6 = 0
(gdb) p p->moff
$7 = 0
(gdb) p p->mlen
$8 = 0
- 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 - 不要最佳化 ( 查 gcc manpage 得知 -O0 可以取消最佳化 )
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.
RETURN VALUE
getutent(), getutid(), getutline() and pututline() return a pointer to
a struct utmp on success, and NULL on failure. This struct utmp is
allocated in static storage, and may be overwritten by subsequent
calls.
FILES
/var/run/utmp database of currently logged-in users
/var/log/wtmp database of past user logins
NOTES
Glibc Notes
The above functions are not thread-safe. Glibc adds reentrant versions
#define _GNU_SOURCE /* or _SVID_SOURCE or _BSD_SOURCE */
#include <utmp.h>
int getutent_r(struct utmp *ubuf, struct utmp **ubufp);
int getutid_r(struct utmp *ut,
struct utmp *ubuf, struct utmp **ubufp);
int getutline_r(struct utmp *ut,
struct utmp *ubuf, struct utmp **ubufp);
These functions are GNU extensions, analogs of the functions of the
same name without the _r suffix. The ubuf parameter gives these func-
tions a place to store their result. On success they return 0, and a
pointer to the result is written in *ubufp. On error these functions
return -1.
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'
