今天同事問我，如何判斷一個.so是否是debug編譯的。
我記得以前自己是用file來查看一個.so，根據(jù)是否包含"not stripped"來判斷該.so是否是debug編譯的，于是就沒做實驗就回答。
然而，stripped/not stripped并不是debug/release編譯的判斷標(biāo)準(zhǔn). 我對debug和release的.so運行file后，得出幾乎相同的輸出， 都是not stripped. 所以我算是誤導(dǎo)同事了。
根據(jù)Computers Systems - A Programmer's Perspective>所言, debug/release的區(qū)別更多的表現(xiàn)在.so和可執(zhí)行程序所擁有的段上。debug編譯出來的。so和可執(zhí)行程序擁有很多附加的段來包含哪些debug的信息。 所以查看段信息是一種判斷的方式。
我在Ubuntu 11.04上分別對同一個開源軟件進行debug和release編譯，并且查看某個.so的段(readelf -S)，發(fā)現(xiàn)release編譯的只有29個段：
There are 29 section headers, starting at offset 0x1b7d78:
Section Headers:
[Nr] Name Type Address Offset
Size EntSize Flags Link Info Align
[ 0] NULL 0000000000000000 00000000
0000000000000000 0000000000000000 0 0 0
[ 1] .note.gnu.build-i NOTE 00000000000001c8 000001c8
0000000000000024 0000000000000000 A 0 0 4
[ 2] .gnu.hash GNU_HASH 00000000000001f0 000001f0
0000000000003430 0000000000000000 A 3 0 8
[ 3] .dynsym DYNSYM 0000000000003620 00003620
000000000000b400 0000000000000018 A 4 2 8
[ 4] .dynstr STRTAB 000000000000ea20 0000ea20
00000000000083e2 0000000000000000 A 0 0 1
[ 5] .gnu.version VERSYM 0000000000016e02 00016e02
0000000000000f00 0000000000000002 A 3 0 2
[ 6] .gnu.version_r VERNEED 0000000000017d08 00017d08
0000000000000080 0000000000000000 A 4 2 8
[ 7] .rela.dyn RELA 0000000000017d88 00017d88
0000000000009570 0000000000000018 A 3 0 8
[ 8] .rela.plt RELA 00000000000212f8 000212f8
00000000000080d0 0000000000000018 A 3 10 8
[ 9] .init PROGBITS 00000000000293c8 000293c8
0000000000000018 0000000000000000 AX 0 0 4
[10] .plt PROGBITS 00000000000293e0 000293e0
00000000000055f0 0000000000000010 AX 0 0 4
[11] .text PROGBITS 000000000002e9d0 0002e9d0
0000000000144658 0000000000000000 AX 0 0 16
[12] .fini PROGBITS 0000000000173028 00173028
000000000000000e 0000000000000000 AX 0 0 4
[13] .rodata PROGBITS 0000000000173040 00173040
000000000001e9a0 0000000000000000 A 0 0 32
[14] .eh_frame_hdr PROGBITS 00000000001919e0 001919e0
000000000000427c 0000000000000000 A 0 0 4
[15] .eh_frame PROGBITS 0000000000195c60 00195c60
0000000000017d7c 0000000000000000 A 0 0 8
[16] .ctors PROGBITS 00000000003ae1e8 001ae1e8
0000000000000010 0000000000000000 WA 0 0 8
[17] .dtors PROGBITS 00000000003ae1f8 001ae1f8
0000000000000010 0000000000000000 WA 0 0 8
[18] .jcr PROGBITS 00000000003ae208 001ae208
0000000000000008 0000000000000000 WA 0 0 8
[19] .data.rel.ro PROGBITS 00000000003ae220 001ae220
0000000000005b38 0000000000000000 WA 0 0 32
[20] .dynamic DYNAMIC 00000000003b3d58 001b3d58
00000000000001a0 0000000000000010 WA 4 0 8
[21] .got PROGBITS 00000000003b3ef8 001b3ef8
00000000000010e8 0000000000000008 WA 0 0 8
[22] .got.plt PROGBITS 00000000003b4fe8 001b4fe8
0000000000002b08 0000000000000008 WA 0 0 8
[23] .data PROGBITS 00000000003b7b00 001b7b00
0000000000000158 0000000000000000 WA 0 0 32
[24] .bss NOBITS 00000000003b7c58 001b7c58
0000000000000010 0000000000000000 WA 0 0 8
[25] .comment PROGBITS 0000000000000000 001b7c58
000000000000002a 0000000000000001 MS 0 0 1
[26] .shstrtab STRTAB 0000000000000000 001b7c82
00000000000000f5 0000000000000000 0 0 1
[27] .symtab SYMTAB 0000000000000000 001b84b8
000000000000fdb0 0000000000000018 28 788 8
[28] .strtab STRTAB 0000000000000000 001c8268
000000000000b8b0 0000000000000000 0 0 1
Key to Flags:
W (write), A (alloc), X (execute), M (merge), S (strings), l (large)
I (info), L (link order), G (group), T (TLS), E (exclude), x (unknown)
O (extra OS processing required) o (OS specific), p (processor specific)
而debug編譯的則有38個段, 且所有比release編譯多出來的段,都是以.debug_作為開始字符串來命名的:
There are 38 section headers, starting at offset 0xdacc00:
Section Headers:
[Nr] Name Type Address Offset
Size EntSize Flags Link Info Align
[ 0] NULL 0000000000000000 00000000
0000000000000000 0000000000000000 0 0 0
[ 1] .note.gnu.build-i NOTE 00000000000001c8 000001c8
0000000000000024 0000000000000000 A 0 0 4
[ 2] .gnu.hash GNU_HASH 00000000000001f0 000001f0
0000000000003620 0000000000000000 A 3 0 8
[ 3] .dynsym DYNSYM 0000000000003810 00003810
000000000000c000 0000000000000018 A 4 2 8
[ 4] .dynstr STRTAB 000000000000f810 0000f810
0000000000008ccb 0000000000000000 A 0 0 1
[ 5] .gnu.version VERSYM 00000000000184dc 000184dc
0000000000001000 0000000000000002 A 3 0 2
[ 6] .gnu.version_r VERNEED 00000000000194e0 000194e0
0000000000000070 0000000000000000 A 4 2 8
[ 7] .rela.dyn RELA 0000000000019550 00019550
0000000000009b40 0000000000000018 A 3 0 8
[ 8] .rela.plt RELA 0000000000023090 00023090
0000000000008388 0000000000000018 A 3 10 8
[ 9] .init PROGBITS 000000000002b418 0002b418
0000000000000018 0000000000000000 AX 0 0 4
[10] .plt PROGBITS 000000000002b430 0002b430
00000000000057c0 0000000000000010 AX 0 0 4
[11] .text PROGBITS 0000000000030bf0 00030bf0
00000000001d2428 0000000000000000 AX 0 0 16
[12] .fini PROGBITS 0000000000203018 00203018
000000000000000e 0000000000000000 AX 0 0 4
[13] .rodata PROGBITS 0000000000203040 00203040
00000000000276b8 0000000000000000 A 0 0 32
[14] .eh_frame_hdr PROGBITS 000000000022a6f8 0022a6f8
00000000000059dc 0000000000000000 A 0 0 4
[15] .eh_frame PROGBITS 00000000002300d8 002300d8
000000000001715c 0000000000000000 A 0 0 8
[16] .ctors PROGBITS 0000000000448018 00248018
0000000000000010 0000000000000000 WA 0 0 8
[17] .dtors PROGBITS 0000000000448028 00248028
0000000000000010 0000000000000000 WA 0 0 8
[18] .jcr PROGBITS 0000000000448038 00248038
0000000000000008 0000000000000000 WA 0 0 8
[19] .data.rel.ro PROGBITS 0000000000448040 00248040
0000000000005b38 0000000000000000 WA 0 0 32
[20] .dynamic DYNAMIC 000000000044db78 0024db78
00000000000001a0 0000000000000010 WA 4 0 8
[21] .got PROGBITS 000000000044dd18 0024dd18
00000000000012d0 0000000000000008 WA 0 0 8
[22] .got.plt PROGBITS 000000000044efe8 0024efe8
0000000000002bf0 0000000000000008 WA 0 0 8
[23] .data PROGBITS 0000000000451be0 00251be0
0000000000000160 0000000000000000 WA 0 0 32
[24] .bss NOBITS 0000000000451d40 00251d40
0000000000000040 0000000000000000 WA 0 0 16
[25] .comment PROGBITS 0000000000000000 00251d40
0000000000000054 0000000000000001 MS 0 0 1
[26] .debug_aranges PROGBITS 0000000000000000 00251d94
00000000000030c0 0000000000000000 0 0 1
[27] .debug_pubnames PROGBITS 0000000000000000 00254e54
000000000000b8cb 0000000000000000 0 0 1
[28] .debug_info PROGBITS 0000000000000000 0026071f
000000000097f69b 0000000000000000 0 0 1
[29] .debug_abbrev PROGBITS 0000000000000000 00bdfdba
0000000000028211 0000000000000000 0 0 1
[30] .debug_line PROGBITS 0000000000000000 00c07fcb
0000000000075fbf 0000000000000000 0 0 1
[31] .debug_str PROGBITS 0000000000000000 00c7df8a
0000000000019789 0000000000000001 MS 0 0 1
[32] .debug_loc PROGBITS 0000000000000000 00c97713
0000000000043528 0000000000000000 0 0 1
[33] .debug_pubtypes PROGBITS 0000000000000000 00cdac3b
00000000000d1c97 0000000000000000 0 0 1
[34] .debug_ranges PROGBITS 0000000000000000 00dac8d2
00000000000001c0 0000000000000000 0 0 1
[35] .shstrtab STRTAB 0000000000000000 00daca92
000000000000016e 0000000000000000 0 0 1
[36] .symtab SYMTAB 0000000000000000 00dad580
0000000000014688 0000000000000018 37 1437 8
[37] .strtab STRTAB 0000000000000000 00dc1c08
000000000000e5a1 0000000000000000 0 0 1
Key to Flags:
W (write), A (alloc), X (execute), M (merge), S (strings), l (large)
I (info), L (link order), G (group), T (TLS), E (exclude), x (unknown)
O (extra OS processing required) o (OS specific), p (processor specific)
對于可執(zhí)行文件也有類似的區(qū)別。
所以這應(yīng)當(dāng)是判斷debug/release的一個比較正確的方法了。
===================================
命令
readelf -S libxxx.so |grep debug
以上這篇Linux下查看.so和可執(zhí)行文件是否debug編譯的方法(必看)就是小編分享給大家的全部內(nèi)容了，希望能給大家一個參考，也希望大家多多支持腳本之家。
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