elf 就是一个文件格式。 可以被操作系统识别并执行。把一个elf格式文件可以简单的理解为一本书
elf 的 header 相当于 目录索引。 我将它称为称为 ELF_Header, 头部大小为 e_ehsize
elf 的 segment 相当于 书中的章
elf 的 section 相当于书中的节。
section header 相当于节的索引。 我将它称为 SH_Header
segment header 相当于 章的索引，我将它称为 PH_Header.
存放SH_Header的表， 我将它成为SH_Table.
根据这三个值 e_shoff， e_shentsize，e_shnum 可以拿到secion表
存放PH_Header的表， 我将它成为PH_Table.
根据这三个值 e_phoff， e_phentsize，e_phnum 可以拿到segment表
总结：
一个或多个section组成一个segment
一个 ELF_Header 加上 一个或多个segment组成一个elf文件。
有一个命令行工具readelf. 可以查看elf一些信息：
查看ELF_Header:
➜ android-ndk-r16b readelf -h /Volumes/dzqExt/source/public/android_cmd/crack/obj/local/armeabi-v7a/libcocos2djs.so ELF Header: Magic: 7f 45 4c 46 01 01 01 00 00 00 00 00 00 00 00 00 Class: ELF32 Data: 2's complement, little endian Version: 1 (current) OS/ABI: UNIX - System V ABI Version: 0 Type: DYN (Shared object file) Machine: ARM Version: 0x1 Entry point address: 0x0 Start of program headers: 52 (bytes into file) Start of section headers: 143852 (bytes into file) Flags: 0x5000200, Version5 EABI, soft-float ABI Size of this header: 52 (bytes) Size of program headers: 32 (bytes) Number of program headers: 8 Size of section headers: 40 (bytes) Number of section headers: 27 Section header string table index: 26
查看所有PH_Header：
➜ android-ndk-r16b readelf --segments /Volumes/dzqExt/source/public/android_cmd/crack/obj/local/armeabi-v7a/libcocos2djs.so Elf file type is DYN (Shared object file) Entry point 0x0 There are 8 program headers, starting at offset 52 Program Headers: Type Offset VirtAddr PhysAddr FileSiz MemSiz Flg Align PHDR 0x000034 0x00000034 0x00000034 0x00100 0x00100 R 0x4 LOAD 0x000000 0x00000000 0x00000000 0x218a7 0x218a7 R E 0x1000 LOAD 0x0224e8 0x000234e8 0x000234e8 0x00b2c 0x00dc9 RW 0x1000 DYNAMIC 0x022ce4 0x00023ce4 0x00023ce4 0x00118 0x00118 RW 0x4 NOTE 0x000134 0x00000134 0x00000134 0x000bc 0x000bc R 0x4 GNU_STACK 0x000000 0x00000000 0x00000000 0x00000 0x00000 RW 0x10 EXIDX 0x01ff94 0x0001ff94 0x0001ff94 0x00728 0x00728 R 0x4 GNU_RELRO 0x0224e8 0x000234e8 0x000234e8 0x00b18 0x00b18 RW 0x4 Section to Segment mapping: Segment Sections... 00 01 .note.android.ident .note.gnu.build-id .dynsym .dynstr .hash .gnu.version .gnu.version_d .gnu.version_r .rel.dyn .rel.plt .plt .text .ARM.extab .ARM.exidx .rodata 02 .fini_array .data.rel.ro .init_array .dynamic .got .data .bss 03 .dynamic 04 .note.android.ident .note.gnu.build-id 05 06 .ARM.exidx 07 .fini_array .data.rel.ro .init_array .dynamic .got
查看所有的SH_header
➜ android-ndk-r16b readelf --sections /Volumes/dzqExt/source/public/android_cmd/crack/obj/local/armeabi-v7a/libcocos2djs.so There are 27 section headers, starting at offset 0x231ec: Section Headers: [Nr] Name Type Addr Off Size ES Flg Lk Inf Al [ 0] NULL 00000000 000000 000000 00 0 0 0 [ 1] .note.android.ide NOTE 00000134 000134 000098 00 A 0 0 4 [ 2] .note.gnu.build-i NOTE 000001cc 0001cc 000024 00 A 0 0 4 [ 3] .dynsym DYNSYM 000001f0 0001f0 0016f0 10 A 4 1 4 [ 4] .dynstr STRTAB 000018e0 0018e0 001c44 00 A 0 0 1 [ 5] .hash HASH 00003524 003524 0009e0 04 A 3 0 4 [ 6] .gnu.version VERSYM 00003f04 003f04 0002de 02 A 3 0 2 [ 7] .gnu.version_d VERDEF 000041e4 0041e4 00001c 00 A 4 1 4 [ 8] .gnu.version_r VERNEED 00004200 004200 000050 00 A 4 2 4 [ 9] .rel.dyn REL 00004250 004250 000ea8 08 A 3 0 4 [10] .rel.plt REL 000050f8 0050f8 000308 08 AI 3 20 4 [11] .plt PROGBITS 00005400 005400 0004a0 00 AX 0 0 4 [12] .text PROGBITS 000058a0 0058a0 017c80 00 AX 0 0 4 [13] .ARM.extab PROGBITS 0001d520 01d520 002a74 00 A 0 0 4 [14] .ARM.exidx ARM_EXIDX 0001ff94 01ff94 000728 08 AL 12 0 4 [15] .rodata PROGBITS 000206c0 0206c0 0011e7 00 A 0 0 16 [16] .fini_array FINI_ARRAY 000234e8 0224e8 000008 04 WA 0 0 4 [17] .data.rel.ro PROGBITS 000234f0 0224f0 0007f0 00 WA 0 0 4 [18] .init_array INIT_ARRAY 00023ce0 022ce0 000004 04 WA 0 0 1 [19] .dynamic DYNAMIC 00023ce4 022ce4 000118 08 WA 4 0 4 [20] .got PROGBITS 00023dfc 022dfc 000204 00 WA 0 0 4 [21] .data PROGBITS 00024000 023000 000014 00 WA 0 0 4 [22] .bss NOBITS 00024020 023014 000291 00 WA 0 0 16 [23] .comment PROGBITS 00000000 023014 000065 01 MS 0 0 1 [24] .note.gnu.gold-ve NOTE 00000000 02307c 00001c 00 0 0 4 [25] .ARM.attributes ARM_ATTRIBUTES 00000000 023098 00003b 00 0 0 1 [26] .shstrtab STRTAB 00000000 0230d3 000117 00 0 0 1 Key to Flags: W (write), A (alloc), X (execute), M (merge), S (strings), I (info), L (link order), O (extra OS processing required), G (group), T (TLS), C (compressed), x (unknown), o (OS specific), E (exclude), y (noread), p (processor specific)
ELF_Header, PH_Header, SH_Header 一起显示
readelf -e xxx.so
