# 在程序入口處打斷點 ## 獲取程序入口 ### 方法一： $ strip a.out $ readelf -h a.out ELF Header: Magic: 7f 45 4c 46 02 01 01 00 00 00 00 00 00 00 00 00 Class: ELF64 Data: 2's complement, little endian Version: 1 (current) OS/ABI: UNIX - System V ABI Version: 0 Type: EXEC (Executable file) Machine: Advanced Micro Devices X86-64 Version: 0x1 Entry point address: 0x400440 Start of program headers: 64 (bytes into file) Start of section headers: 4496 (bytes into file) Flags: 0x0 Size of this header: 64 (bytes) Size of program headers: 56 (bytes) Number of program headers: 9 Size of section headers: 64 (bytes) Number of section headers: 29 Section header string table index: 28 ### 方法二： $ gdb a.out >>> info files Symbols from "/home/me/a.out". Local exec file: `/home/me/a.out', file type elf64-x86-64. Entry point: 0x400440 0x0000000000400238 - 0x0000000000400254 is .interp 0x0000000000400254 - 0x0000000000400274 is .note.ABI-tag 0x0000000000400274 - 0x0000000000400298 is .note.gnu.build-id 0x0000000000400298 - 0x00000000004002b4 is .gnu.hash 0x00000000004002b8 - 0x0000000000400318 is .dynsym 0x0000000000400318 - 0x0000000000400355 is .dynstr 0x0000000000400356 - 0x000000000040035e is .gnu.version 0x0000000000400360 - 0x0000000000400380 is .gnu.version_r 0x0000000000400380 - 0x0000000000400398 is .rela.dyn 0x0000000000400398 - 0x00000000004003e0 is .rela.plt 0x00000000004003e0 - 0x00000000004003fa is .init 0x0000000000400400 - 0x0000000000400440 is .plt 0x0000000000400440 - 0x00000000004005c2 is .text 0x00000000004005c4 - 0x00000000004005cd is .fini 0x00000000004005d0 - 0x00000000004005e0 is .rodata 0x00000000004005e0 - 0x0000000000400614 is .eh_frame_hdr 0x0000000000400618 - 0x000000000040070c is .eh_frame 0x0000000000600e10 - 0x0000000000600e18 is .init_array 0x0000000000600e18 - 0x0000000000600e20 is .fini_array 0x0000000000600e20 - 0x0000000000600e28 is .jcr 0x0000000000600e28 - 0x0000000000600ff8 is .dynamic 0x0000000000600ff8 - 0x0000000000601000 is .got 0x0000000000601000 - 0x0000000000601030 is .got.plt 0x0000000000601030 - 0x0000000000601040 is .data 0x0000000000601040 - 0x0000000000601048 is .bss ## 技巧 當調試沒有調試信息的程序時，直接運行`start`命令是沒有效果的： (gdb) start Function "main" not defined. 如果不知道main在何處，那么可以在程序入口處打斷點。先通過`readelf`或者進入gdb，執行`info files`獲得入口地址，然后： (gdb) b *0x400440 (gdb) r ## 貢獻者 * xmj * [weekface](https://github.com/weekface)