linux - 为什么不带 "not stripped, with debug_info"选项的可执行文件file命令在编译时报 "-g"？

Question

我的操作系统是Arch Linux，test.c程序很简单:

# cat test.c
#include <stdio.h>

int main(void) {
        printf("Hello world!\n");
}

不带-g选项编译，使用file命令查看可执行文件信息:

# gcc test.c
# file a.out
a.out: ELF 64-bit LSB executable, x86-64, version 1 (SYSV), dynamically linked, interpreter /lib64/ld-linux-x86-64.so.2, for GNU/Linux 2.6.32, BuildID[sha1]=c7a538046222b5209d2daafbfc246de341a652d9, not stripped, with debug_info

file 命令输出“not stripped, with debug_info”，但我在编译期间没有使用 -g 选项。使用gdb调试a.out:

# gdb a.out
GNU gdb (GDB) 7.12.1
Copyright (C) 2017 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-pc-linux-gnu".
Type "show configuration" for configuration details.
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>.
Find the GDB manual and other documentation resources online at:
<http://www.gnu.org/software/gdb/documentation/>.
For help, type "help".
Type "apropos word" to search for commands related to "word"...
Reading symbols from a.out...(no debugging symbols found)...done.
(gdb)

我可以看到 gdb 还提示“Reading symbols from a.out...(no debugging symbols found)...done.”。

为什么file命令在编译过程中报告“not stripped, with debug_info”没有“-g”选项的可执行文件？

Answer 1

Why does file command report "not stripped, with debug_info" of the executable file without "-g" option during compilation?

您的程序链接到 libc_nonshared.a 的部分(例如，c 运行时启动 ctr0.o)，其中可能包含一些调试信息。

您可以看到可用的调试信息并猜测它来自哪里:

readelf -wl ./a.out