數位天堂

James · 2008-10-29 14:30:42

寫了一支程式fstat64.c來測試系統是否支援fstat64函式

#include 
#include 
#include 
 
int main(void)
{
  struct stat buf;
  fstat64 ("/tmp", &buf);
  return 0;
}

利用Cross-Comoiler編譯：

　　# mipsel-linuc-gcc -o fstat64 fstat64.c

查看它需要什麼shared library

　　# mipsel-linux-objdump -p fstat64

fstat64:     file format elf32-tradlittlemips

Program Header:
    PHDR off    0x00000034 vaddr 0x00400034 paddr 0x00400034 align 2**2
         filesz 0x000000c0 memsz 0x000000c0 flags r-x
  INTERP off    0x000000f4 vaddr 0x004000f4 paddr 0x004000f4 align 2**0
         filesz 0x00000014 memsz 0x00000014 flags r--
0x70000000 off    0x00000108 vaddr 0x00400108 paddr 0x00400108 align 2**2
         filesz 0x00000018 memsz 0x00000018 flags r--
    LOAD off    0x00000000 vaddr 0x00400000 paddr 0x00400000 align 2**12
         filesz 0x000008f4 memsz 0x000008f4 flags r-x
    LOAD off    0x00001000 vaddr 0x10000000 paddr 0x10000000 align 2**12
         filesz 0x0000009c memsz 0x000000c0 flags rw-
 DYNAMIC off    0x00000120 vaddr 0x00400120 paddr 0x00400120 align 2**2
         filesz 0x000003e0 memsz 0x000003e0 flags rwx

Dynamic Section:
  NEEDED      libgcc_s.so.1
  NEEDED      libc.so.0
  INIT        0x40054c
  FINI        0x400870
  HASH        0x400218
  STRTAB      0x400408
  SYMTAB      0x4002b8
  STRSZ       0xf8
  SYMENT      0x10
  0x70000016  0x10000050
  DEBUG       0x0
  PLTGOT      0x10000060
  REL         0x0
  RELSZ       0x0
  RELENT      0x8
  0x70000001  0x1
  0x70000005  0x2
  0x70000006  0x400000
  0x7000000a  0x7
  0x70000011  0x15
  0x70000012  0x1a
  0x70000013  0xd
  VERNEED     0x40052c
  VERNEEDNUM  0x1
  VERSYM      0x400500

Version References:
  required from libgcc_s.so.1:
    0x0b792650 0x00 02 GCC_3.0
private flags = 50001007: [abi=O32] [mips32] [not 32bitmode]

得知它需要：

　　NEEDED libgcc_s.so.1
　　NEEDED libc.so.0

並且查看它實際上呼叫是什麼函式：

　　# mipsel-linux-objdump -T fstat64
　　fstat64: file format elf32-tradlittlemips

　　DYNAMIC SYMBOL TABLE:
　　10000020 g D .data 00000000 Base _fdata
　　10008050 g d *ABS* 00000000 _gp_disp
　　00000001 g d *ABS* 00000000 Base _DYNAMIC_LINKING
　　00400120 g DO *ABS* 00000000 Base _DYNAMIC
　　10008050 g D *ABS* 00000000 Base _gp
　　004005e0 g D .text 00000000 Base _ftext
　　10000050 g DO .rld_map 00000000 Base __RLD_MAP
　　1000009c g D *ABS* 00000000 Base __bss_start
　　1000009c g D *ABS* 00000000 Base _edata
　　10000060 g DO *ABS* 00000000 Base _GLOBAL_OFFSET_TABLE_
　　100000c0 g D *ABS* 00000000 Base _end
　　1000009c g D *ABS* 00000000 Base _fbss
　　00000000 w D *UND* 00000000 _Jv_RegisterClasses
　　00000000 w DF *UND* 0000001c GCC_3.0 __register_frame_info
　　00400870 g DF .fini 0000001c Base _fini
　　00400770 g DF .text 00000064 Base main
　　00400850 DF *UND* 00000244 __uClibc_main
　　00000000 w DF *UND* 0000001c GCC_3.0 __deregister_frame_info
　　0040054c g DF .init 0000001c Base _init
　　00400840 DF *UND* 00000094 fstat64

telnet到ASUS WL-500gP的平台上，到/jffs/opt/lib的目錄中下，查看

　　/jffs/opt/lib # ls -al libc.so.0
　　lrwxrwxrwx 1 root root 19 Oct 23 08:55 libc.so.0 -> libuClibc-0.9.28.so

於是將libuClibc-0.9.28.so，利用ftp的方式將它上傳到Host Platform。

　　# mipsel-linux-objdump -D libuClibc-0.9.28.so > dump
　　# vim dump

確實查得到fstat64函式的section：

00052090 :
  52090:       3c1c0006        lui     gp,0x6
  52094:       279c4710        addiu   gp,gp,18192
  52098:       0399e021        addu    gp,gp,t9
  5209c:       27bdff70        addiu   sp,sp,-144
  520a0:       afbf0088        sw      ra,136(sp)
  520a4:       afb10084        sw      s1,132(sp)
  520a8:       afb00080        sw      s0,128(sp)
  520ac:       afbc0010        sw      gp,16(sp)
  520b0:       27a60018        addiu   a2,sp,24
  520b4:       00a08821        move    s1,a1
  520b8:       00c02821        move    a1,a2
  520bc:       24021077        li      v0,4215
  520c0:       0000000c        syscall
  520c4:       8f9981f8        lw      t9,-32264(gp)
  520c8:       10e00007        beqz    a3,520e8 
  520cc:       00408021        move    s0,v0
  520d0:       0320f809        jalr    t9
  520d4:       00000000        nop
  520d8:       8fbc0010        lw      gp,16(sp)
  520dc:       2403ffff        li      v1,-1
  520e0:       1000000a        b       5210c 
  520e4:       ac500000        sw      s0,0(v0)
  520e8:       8f998558        lw      t9,-31400(gp)
  520ec:       00401821        move    v1,v0
  520f0:       00c02021        move    a0,a2
  520f4:       14400005        bnez    v0,5210c 
  520f8:       02202821        move    a1,s1
  520fc:       0320f809        jalr    t9
  52100:       00000000        nop
  52104:       8fbc0010        lw      gp,16(sp)
  52108:       00001821        move    v1,zero
  5210c:       8fbf0088        lw      ra,136(sp)
  52110:       8fb10084        lw      s1,132(sp)
  52114:       8fb00080        lw      s0,128(sp)
  52118:       00601021        move    v0,v1
  5211c:       03e00008        jr      ra
  52120:       27bd0090        addiu   sp,sp,144
       ...

將fstat64放到ASUS WL-500gP上去執行，執行前先設置環境

mount -o bind /jffs/opt /opt
export PATH=/bin:/usr/bin:/sbin:/usr/sbin:/jffs/sbin:/jffs/bin:/jffs/usr/sbin:/jffs/usr/bin:/jffs/opt/bin
export LD_LIBRARY_PATH=/lib:/usr/lib:/jffs/opt/lib:/jffs/lib:/jffs/usr/lib:/jffs/usr/local/lib

執行：
　　~ # ./fstat64
　　./fstat64: can't resolve symbol 'fstat64'

實在為清楚為什麼，在library查得到fstat64的symbol及section，但卻會產生can't resolve symbol的問題。 orz
還是在trace的過程有什麼沒注意的。

James · 2008-10-29 16:22:47

我知道了~
我在設定LD_LIBRARY_PATH中：

　　export LD_LIBRARY_PATH=/lib:/usr/lib:/jffs/opt/lib:/jffs/lib:/jffs/usr/lib:/jffs/usr/local/lib

在/lib的目錄中有libc.so.0，在執行fstat64程式時，會先到/lib搜尋，恰好有《libc.so.0》，但我猜測這個程式庫沒有fstat64(之所以用猜測的，因為我用objdump印不出來任何的symbol)，所以就會告知找不到fstat64 symbol。我重新調換一下：

　　export LD_LIBRARY_PATH=/jffs/opt/lib:/lib:/usr/lib:/jffs/lib:/jffs/usr/lib:/jffs/usr/local/lib

問題解決了！

James · 2008-10-29 16:47:01

調換了LD_LIBRARY_PATH之後，
執行wget會發生Segmentation fault，怪怪~ orz 一冷一熱
　~ # wget http://xxx.yyy.zzz/filename
　Connecting to xxx.yyy.zzz[xxx.yyy.zzz]:80
　Segmentation fault

這該怎麼trace呢？ crybaby

hippo · 2008-10-29 23:07:41

請善用shell.

James · 2008-10-30 08:49:42

hippo大大~
我不太了解善用shell，是指我使用的方式不對呢？
還是善用shell來追綜Segmentation fault的問題，如果是這樣，可以指點一下方向嗎？ grin

hippo · 2008-10-30 14:01:54

請參考這裡
在console模式下, sh, 建立shell測試或建立script測試.

James · 2008-10-30 14:08:53

hippo大大~
這一次我真得不能了解你說的方向... 能在給予一些指點嗎？
wacko

hippo · 2008-10-30 14:41:37

DD-WRT v24 std (c) 2008 NewMedia-NET GmbH
Release: 10/22/08 (SVN revision: 10564)

WL-500gx login: root
Password:
==========================================================

 ____  ___    __        ______ _____         ____  _  _
 | _ \| _ \   \ \      / /  _ \_   _| __   _|___ \| || |
 || | || ||____\ \ /\ / /| |_) || |   \ \ / / __) | || |_
 ||_| ||_||_____\ V  V / |  _ < | |    \ V / / __/|__   _|
 |___/|___/      \_/\_/  |_| \_\|_|     \_/ |_____|  |_|

                       DD-WRT v24
                   http://www.dd-wrt.com

==========================================================


BusyBox v1.12.1 (2008-10-22 15:25:40 CEST) built-in shell (ash)
Enter 'help' for a list of built-in commands.

root@WL-500gx:~# sh


BusyBox v1.12.1 (2008-10-22 15:25:40 CEST) built-in shell (ash)
Enter 'help' for a list of built-in commands.

root@WL-500gx:~#

現在可以胡搞了.

DD-WRT v24 std (c) 2008 NewMedia-NET GmbH
Release: 10/22/08 (SVN revision: 10564)

WL-500gx login: root
Password:
==========================================================

 ____  ___    __        ______ _____         ____  _  _
 | _ \| _ \   \ \      / /  _ \_   _| __   _|___ \| || |
 || | || ||____\ \ /\ / /| |_) || |   \ \ / / __) | || |_
 ||_| ||_||_____\ V  V / |  _ < | |    \ V / / __/|__   _|
 |___/|___/      \_/\_/  |_| \_\|_|     \_/ |_____|  |_|

                       DD-WRT v24
                   http://www.dd-wrt.com

==========================================================


BusyBox v1.12.1 (2008-10-22 15:25:40 CEST) built-in shell (ash)
Enter 'help' for a list of built-in commands.

root@WL-500gx:~# cat > /tmp/test.sh
#!/bin/sh
ls -al
root@WL-500gx:~# chmod +x /tmp/test.sh
root@WL-500gx:~# /tmp/test.sh
drwxr-xr-x   16 root     root          153 Oct 22 13:28 .
drwxr-xr-x   16 root     root          153 Oct 22 13:28 ..
drwxr-xr-x    2 root     root          498 Oct 22 13:28 bin
drwxr-xr-x    1 root     root            0 Jan  1  1970 dev
drwxr-xr-x    5 root     root          380 Oct 22 13:28 etc
drwxr-xr-x    7 root     root         1024 Oct 15 23:03 jffs
drwxr-xr-x    3 root     root          242 Oct 22 13:28 lib
drwxr-xr-x    2 root     root            3 Oct 22 13:28 mmc
drwxr-xr-x    2 root     root            3 Oct 22 13:28 mnt
drwxr-xr-x   19 root     root         4096 Oct 29 05:29 opt
dr-xr-xr-x   49 root     root            0 Jan  1  2000 proc
drwxr-xr-x    2 root     root          973 Oct 22 13:28 sbin
drwxr-xr-x    2 root     root            3 Oct 22 13:28 sys
drwxrwxrwx    1 root     root            0 Jan  1  2000 tmp
drwxr-xr-x    7 root     root           76 Oct 22 13:28 usr
lrwxrwxrwx    1 root     root            7 Oct 22 13:28 var -> tmp/var
drwxr-xr-x    7 root     root          112 Oct 22 13:28 www
root@WL-500gx:~#

這是簡單的script, 提供您觀念上的參考.

James · 2008-10-30 15:07:30

哈哈~ 這個sh不錯用的樣子。
但我比較想了解為什麼

　　export LD_LIBRARY_PATH=/lib:/usr/lib:/jffs/opt/lib:/jffs/lib:/jffs/usr/lib:/jffs/usr/local/lib

改成這一行

　　export LD_LIBRARY_PATH=/jffs/opt/lib:/lib:/usr/lib:/jffs/lib:/jffs/usr/lib:/jffs/usr/local/lib

執行wget會發生Segmentation fault說！ big_smile

hippo · 2008-10-30 15:58:35

DD-WRT v24 std (c) 2008 NewMedia-NET GmbH
Release: 10/22/08 (SVN revision: 10564)

WL-500gx login: root
Password:
==========================================================

 ____  ___    __        ______ _____         ____  _  _
 | _ \| _ \   \ \      / /  _ \_   _| __   _|___ \| || |
 || | || ||____\ \ /\ / /| |_) || |   \ \ / / __) | || |_
 ||_| ||_||_____\ V  V / |  _ < | |    \ V / / __/|__   _|
 |___/|___/      \_/\_/  |_| \_\|_|     \_/ |_____|  |_|

                       DD-WRT v24
                   http://www.dd-wrt.com

==========================================================


BusyBox v1.12.1 (2008-10-22 15:25:40 CEST) built-in shell (ash)
Enter 'help' for a list of built-in commands.

root@WL-500gx:~# echo $LD_LIBRARY_PATH
/lib:/usr/lib:/jffs/lib:/jffs/usr/lib:/jffs/usr/local/lib
root@WL-500gx:~# cd /tmp
root@WL-500gx:/tmp# wget http://downloads.openwrt.org/whiterussian/packages/ipkg_0.99.149-2_mipsel.ipk
Connecting to downloads.openwrt.org (195.56.146.238:80)
root@WL-500gx:/tmp# rm ipkg_0.99.149-2_mipsel.ipk
root@WL-500gx:/tmp# export LD_LIBRARY_PATH=/opt/lib:/jffs/opt/lib:/lib:/usr/lib:/jffs/lib:/jffs/usr/lib:/jffs/
usr/local/lib
root@WL-500gx:/tmp# wget http://downloads.openwrt.org/whiterussian/packages/ipkg_0.99.149-2_mipsel.ipk
Connecting to downloads.openwrt.org (195.56.146.238:80)
Segmentation fault
root@WL-500gx:/tmp# cat > test.sh
#!/bin/sh
export LD_LIBRARY_PATH=/lib:/usr/lib:/jffs/lib:/jffs/usr/lib:/jffs/usr/local/lib
$1 $2
root@WL-500gx:/tmp# chmod +x test.sh
root@WL-500gx:/tmp# ./test.sh wget http://downloads.openwrt.org/whiterussian/packages/ipkg_0.99.149-2_mipsel.i
pk
Connecting to downloads.openwrt.org (195.56.146.238:80)
root@WL-500gx:/tmp# ls -al
drwxrwxrwx    1 root     root            0 Jan  1  2000 .
drwxr-xr-x   16 root     root          153 Oct 22 13:28 ..
-rw-------    1 root     root         1925 Oct 30 13:36 .ipt
-rwx------    1 root     root           99 Oct 30 13:36 .rc_firewall
-rwx------    1 root     root           34 Jan  1  1970 .rc_startup
-rw-r--r--    1 root     root           20 Oct 30 13:36 .rule
-rw-------    1 root     root            9 Oct 30 13:36 .wanuptime
drwx------    1 root     root            0 Jan  1  1970 cron.d
-rw-r--r--    1 root     root            0 Jan  1  1970 crontab
drwx------    1 root     root            0 Jan  1  1970 ddns
-rw-r--r--    1 root     root          211 Jan  1  1970 dnsmasq.conf
-rw-r--r--    1 root     root           63 Oct 30 13:38 dnsmasq.leases
drwx------    1 root     root            0 Jan  1  1970 etc
-rw-r--r--    1 root     root           41 Jan  1  1970 hosts
-rw-------    1 root     root          205 Oct 30 13:36 igmpproxy.conf
-rw-r--r--    1 root     root        62784 Oct 30 15:57 ipkg_0.99.149-2_mipsel.ipk
-rw-r--r--    1 root     root           82 Jan  1  1970 loginprompt
srwxr-xr-x    1 root     root            0 Jan  1  1970 php-fcgi.sock-0
drwxr-xr-x    1 root     root            0 Jan  1  1970 ppp
-rw-r--r--    1 root     root           23 Jan  1  1970 resolv.conf
-rw-r--r--    1 root     root           75 Jan  1  1970 resolv.dnsmasq
drwx------    1 root     root            0 Jan  1  1970 root
-rwxr-xr-x    1 root     root           97 Oct 30 15:55 test.sh
drwxr-xr-x    1 root     root            0 Jan  1  2000 var
drwxr-xr-x    1 root     root            0 Jan  1  1970 vsftpd
drwxr-xr-x    1 root     root            0 Jan  1  2000 www

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數位天堂

#1 2008-10-29 14:30:42

ASUS WL-500gP的library是否支援fstat64函式追蹤

#2 2008-10-29 16:22:47

Re: ASUS WL-500gP的library是否支援fstat64函式追蹤

#3 2008-10-29 16:47:01

Re: ASUS WL-500gP的library是否支援fstat64函式追蹤

#4 2008-10-29 23:07:41

Re: ASUS WL-500gP的library是否支援fstat64函式追蹤

#5 2008-10-30 08:49:42

Re: ASUS WL-500gP的library是否支援fstat64函式追蹤

#6 2008-10-30 14:01:54

Re: ASUS WL-500gP的library是否支援fstat64函式追蹤

#7 2008-10-30 14:08:53

Re: ASUS WL-500gP的library是否支援fstat64函式追蹤

#8 2008-10-30 14:41:37

Re: ASUS WL-500gP的library是否支援fstat64函式追蹤

#9 2008-10-30 15:07:30

Re: ASUS WL-500gP的library是否支援fstat64函式追蹤

#10 2008-10-30 15:58:35

Re: ASUS WL-500gP的library是否支援fstat64函式追蹤

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