blocks|key|1629717|text|我认为像这样的事情应该有效：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1629718|制作一个简单的C程序|ordered-list-item|1629719|gcc+-S文件|1629720|编辑文件|1629721|气体文件|1629722|-lc+crt1.o+-o+myprog|1629723|entityMap^0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|P|8|@]|9|@]|A|$]]|$1|E|3|F|5|D|7|Q|8|@]|9|@]|A|$]]|$1|G|3|H|5|D|7|R|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|S|8|@]|9|@]|A|$]]|$1|K|3|L|5|D|7|T|8|@]|9|@]|A|$]]|$1|M|3|-4|5|6|7|U|8|@]|9|@]|A|$]]]|N|$]]

I think something like this should work:

<ol>
<li>make a simple C program </li>
<li>gcc -S file.c </li>
<li>edit file.s </li>
<li>gas file.s</li>
<li>ld file.o -lc crt1.o -o myprog</li>
</ol>

blocks|key|1629748|text|要成功地在动态链接中使用libc，至少需要做三件事：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1629749|链接/usr/lib/crt1.o，其中包含_start，这将是ELF二进制文件的入口点；|ordered-list-item|offset|length|style|CODE|1629750|链接/usr/lib/crti.o+(在libc之前)和/usr/lib/crtn.o+(后)，提供一些初始化和终结代码；|1629751|告诉链接器，二进制程序将使用动态链接器/lib/ld-linux.so。|1629752|例如：|1629753|$+cat+hello.s
+.text
+.globl+main
main:
+push+%25ebp
+mov+%25esp,+%25ebp
+pushl+$hw_str
+call+puts
+add+$4,+%25esp
+xor+%25eax,+%25eax
+leave
+ret

+.data
hw_str:
+.asciz+"Hello+world!"

$+as+-o+hello.o+hello.s
$+ld+-o+hello+-dynamic-linker+/lib/ld-linux.so.2+/usr/lib/crt1.o+/usr/lib/crti.o+-lc+hello.o+/usr/lib/crtn.o
$+./hello
Hello+world!
$|code-block|syntax|javascript|1629754|entityMap^0|0|2|F|M|6|0|2|F|S|F|0|J|G|0|0|0^^$0|@$1|2|3|4|5|6|7|V|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|W|8|@$E|X|F|Y|G|H]|$E|Z|F|10|G|H]]|9|@]|A|$]]|$1|I|3|J|5|D|7|11|8|@$E|12|F|13|G|H]|$E|14|F|15|G|H]]|9|@]|A|$]]|$1|K|3|L|5|D|7|16|8|@$E|17|F|18|G|H]]|9|@]|A|$]]|$1|M|3|N|5|6|7|19|8|@]|9|@]|A|$]]|$1|O|3|P|5|Q|7|1A|8|@]|9|@]|A|$R|S]]|$1|T|3|-4|5|6|7|1B|8|@]|9|@]|A|$]]]|U|$]]

There are at least three things that you need to do to successfully use libc with dynamic linking:

<ol>
<li>Link <code>/usr/lib/crt1.o</code>, which contains <code>_start</code>, which will be the entry point for the ELF binary;</li>
<li>Link <code>/usr/lib/crti.o</code> (before libc) and <code>/usr/lib/crtn.o</code> (after), which provide some initialisation and finalisation code;</li>
<li>Tell the linker that the binary will use the dynamic linker, <code>/lib/ld-linux.so</code>.</li>
</ol>

For example:

<pre><code>$ cat hello.s
 .text
 .globl main
main:
 push %ebp
 mov %esp, %ebp
 pushl $hw_str
 call puts
 add $4, %esp
 xor %eax, %eax
 leave
 ret

 .data
hw_str:
 .asciz "Hello world!"

$ as -o hello.o hello.s
$ ld -o hello -dynamic-linker /lib/ld-linux.so.2 /usr/lib/crt1.o /usr/lib/crti.o -lc hello.o /usr/lib/crtn.o
$ ./hello
Hello world!
$
</code></pre>

blocks|key|1984212|text|如果在程序集main中定义，则为|type|unstyled|depth|inlineStyleRanges|offset|length|style|BOLD|CODE|entityRanges|data|1984213|马修的回答在告诉你最低要求方面做得很好。|1984214|让我向您展示如何在您的系统中找到这些路径。运行：|1984215|gcc+-v+hello_world.c+%7C&+grep+'collect2'+%7C+tr+'+'+'\n'|code-block|syntax|javascript|1984216|然后拿起马修提到的文件。|1984217|gcc+-v为您提供GCC使用的链接器命令。|1984218|collect2是GCC作为链接器前端使用的内部可执行文件，它具有与ld类似的接口。|1984219|在Ubuntu+14.04+64位(GCC+4.8)，我结束了：|1984220|ld+-dynamic-linker+/lib64/ld-linux-x86-64.so.2+\
++/usr/lib/x86_64-linux-gnu/crt1.o+\
++/usr/lib/x86_64-linux-gnu/crti.o+\
++-lc+hello_world.o+\
++/usr/lib/x86_64-linux-gnu/crtn.o|1984221|您还可能需要-lgcc和-lgcc_s。另见：我真的需要libgcc吗？|1984222|如果在程序集_start中定义，则为|1984223|如果我定义了_start，那么glibc的hello只使用：|1984224|ld+-dynamic-linker+/lib64/ld-linux-x86-64.so.2+-lc+hello_world.o|1984225|我不确定这是否健壮，即是否可以安全地跳过crt初始化来调用glibc函数。另见：为什么装配程序只在与crt1.ocrti.o和crtn.o链接时才能工作？|1984226|entityMap|0|LINK|mutability|MUTABLE|url|https://gcc.gnu.org/onlinedocs/gcc-4.3.5/gccint/Collect2.html|1|https://stackoverflow.com/questions/9414625/do-i-really-need-libgcc|2|https://stackoverflow.com/questions/18091463/assembly-program-only-works-when-linked-with-crt1-o-crti-o-and-crtn-o-why^0|6|4|D|3|6|4|0|0|K|0|0|O|0|0|0|C|0|0|M|0|6|0|0|16|Y|2|0|8|0|0|0|W|0|0|0|10|6|5|C|7|N|D|1|0|0|I|6|6|0|0|U|6|6|0|0|0|25|K|3|14|11|2|0^^$0|@$1|2|3|4|5|6|7|1L|8|@$9|1M|A|1N|B|C]|$9|1O|A|1P|B|C]|$9|1Q|A|1R|B|D]]|E|@]|F|$]]|$1|G|3|H|5|6|7|1S|8|@$9|1T|A|1U|B|C]]|E|@]|F|$]]|$1|I|3|J|5|6|7|1V|8|@$9|1W|A|1X|B|C]]|E|@]|F|$]]|$1|K|3|L|5|M|7|1Y|8|@]|E|@]|F|$N|O]]|$1|P|3|Q|5|6|7|1Z|8|@$9|20|A|21|B|C]]|E|@]|F|$]]|$1|R|3|S|5|6|7|22|8|@$9|23|A|24|B|C]|$9|25|A|26|B|D]]|E|@]|F|$]]|$1|T|3|U|5|6|7|27|8|@$9|28|A|29|B|C]|$9|2A|A|2B|B|D]]|E|@$9|2C|A|2D|1|2E]]|F|$]]|$1|V|3|W|5|6|7|2F|8|@$9|2G|A|2H|B|C]]|E|@]|F|$]]|$1|X|3|Y|5|M|7|2I|8|@]|E|@]|F|$N|O]]|$1|Z|3|10|5|6|7|2J|8|@$9|2K|A|2L|B|C]|$9|2M|A|2N|B|D]|$9|2O|A|2P|B|D]]|E|@$9|2Q|A|2R|1|2S]]|F|$]]|$1|11|3|12|5|6|7|2T|8|@$9|2U|A|2V|B|C]|$9|2W|A|2X|B|D]]|E|@]|F|$]]|$1|13|3|14|5|6|7|2Y|8|@$9|2Z|A|30|B|C]|$9|31|A|32|B|D]]|E|@]|F|$]]|$1|15|3|16|5|M|7|33|8|@]|E|@]|F|$N|O]]|$1|17|3|18|5|6|7|34|8|@$9|35|A|36|B|C]|$9|37|A|38|B|D]]|E|@$9|39|A|3A|1|3B]]|F|$]]|$1|19|3|-4|5|6|7|3C|8|@]|E|@]|F|$]]]|1A|$1B|$5|1C|1D|1E|F|$1F|1G]]|1H|$5|1C|1D|1E|F|$1F|1I]]|1J|$5|1C|1D|1E|F|$1F|1K]]]]

If you define <code>main</code> in assembly

Matthew's answer does a great job of telling you the minimum requirements.

Let me show you how how to find those paths in your system. Run:

<pre><code>gcc -v hello_world.c |&amp; grep 'collect2' | tr ' ' '\n'
</code></pre>

and then pick up the files Matthew mentioned.

<code>gcc -v</code> gives you the exact linker command GCC uses.

<a href="https://gcc.gnu.org/onlinedocs/gcc-4.3.5/gccint/Collect2.html" rel="nofollow noreferrer">collect2</a> is the internal executable GCC uses as a linker front-end, which has a similar interface to <code>ld</code>. 

In Ubuntu 14.04 64-bit (GCC 4.8), I ended up with:

<pre><code>ld -dynamic-linker /lib64/ld-linux-x86-64.so.2 \
 /usr/lib/x86_64-linux-gnu/crt1.o \
 /usr/lib/x86_64-linux-gnu/crti.o \
 -lc hello_world.o \
 /usr/lib/x86_64-linux-gnu/crtn.o
</code></pre>

You might also need <code>-lgcc</code> and <code>-lgcc_s</code>. See also: <a href="https://stackoverflow.com/questions/9414625/do-i-really-need-libgcc">Do I really need libgcc?</a>

If you define <code>_start</code> in assembly

If I defined the <code>_start</code>, the hello world from glibc worked with just:

<pre><code>ld -dynamic-linker /lib64/ld-linux-x86-64.so.2 -lc hello_world.o
</code></pre>

I'm not sure if this is robust, i.e. if the <code>crt</code> initializations can be safely skipped to invoke glibc functions. See also: <a href="https://stackoverflow.com/questions/18091463/assembly-program-only-works-when-linked-with-crt1-o-crti-o-and-crtn-o-why">Why does an assembly program only work when linked with crt1.o crti.o and crtn.o?</a>

blocks|key|1629908|text|如果您确实使用_start而不是main+(如上面的一些注释中所提到的)，您还需要更改程序退出的方式，否则就会出现seg错误：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1629909|++++++++++++.text
++++++++++++.globl++++_start
_start:+++++
++++++++++++mov+++++++$hw_str,+%25rdi
++++++++++++call++++++puts
++++++++++++movl++++++$0,%25ebx+++#+first+argument:+exit+code.
++++++++++++movl++++++$1,%25eax+++#+system+call+number:+sys_exit.
++++++++++++int+++++++$0x80+++++#+call+kernel.

++++++++++++.data
hw_str:+++++.asciz+"Hello+world!"|code-block|syntax|javascript|1629910|关于库本图18.04.2+(gcc+(Ubuntu+7.3.0-27+ubuntu1~18.04)+7.3.0)：|1629911|$+as+-o+hello.o+hello.s
$+ld+-dynamic-linker+/lib64/ld-linux-x86-64.so.2+-o+hello+hello.o+-lc|1629912|另外，了解系统上动态链接器的一个简单方法是编译一个小C程序，然后在二进制文件上运行ldd：|1629913|测试.c：|1629914|int+main()+{+return+0;+}|1629915|针对可执行文件编译和运行ldd：|1629916|$+gcc+-o+test+test.c
$+ldd+test
++++linux-vdso.so.1+(0x00007ffd0a182000)
++++libc.so.6+=>+/lib/x86_64-linux-gnu/libc.so.6+(0x00007ff24d8e6000)
++++/lib64/ld-linux-x86-64.so.2+(0x00007ff24ded9000)|1629917|entityMap^0|7|6|G|4|0|0|0|0|15|3|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|10|8|@$9|11|A|12|B|C]|$9|13|A|14|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|15|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|16|8|@]|D|@]|E|$]]|$1|M|3|N|5|H|7|17|8|@]|D|@]|E|$I|J]]|$1|O|3|P|5|6|7|18|8|@$9|19|A|1A|B|C]]|D|@]|E|$]]|$1|Q|3|R|5|6|7|1B|8|@]|D|@]|E|$]]|$1|S|3|T|5|H|7|1C|8|@]|D|@]|E|$I|J]]|$1|U|3|V|5|6|7|1D|8|@]|D|@]|E|$]]|$1|W|3|X|5|H|7|1E|8|@]|D|@]|E|$I|J]]|$1|Y|3|-4|5|6|7|1F|8|@]|D|@]|E|$]]]|Z|$]]

If you do use <code>_start</code> instead of <code>main</code> (as mentioned in some of the comments above), you'll also need to change the way the program exits, or you'll get a seg fault:

<pre><code> .text
 .globl _start
_start: 
 mov $hw_str, %rdi
 call puts
 movl $0,%ebx # first argument: exit code.
 movl $1,%eax # system call number: sys_exit.
 int $0x80 # call kernel.

 .data
hw_str: .asciz "Hello world!"
</code></pre>

On Kubuntu 18.04.2 (gcc (Ubuntu 7.3.0-27ubuntu1~18.04) 7.3.0):

<pre><code>$ as -o hello.o hello.s
$ ld -dynamic-linker /lib64/ld-linux-x86-64.so.2 -o hello hello.o -lc
</code></pre>

Also, one easy way to find out what the dynamic linker is on your system is to compile a small C program and then run <code>ldd</code> on the binary:

test.c:

<pre><code>int main() { return 0; }
</code></pre>

Compile and run ldd against executable:

<pre><code>$ gcc -o test test.c
$ ldd test
 linux-vdso.so.1 (0x00007ffd0a182000)
 libc.so.6 =&gt; /lib/x86_64-linux-gnu/libc.so.6 (0x00007ff24d8e6000)
 /lib64/ld-linux-x86-64.so.2 (0x00007ff24ded9000)
</code></pre>

As an exercise to learn more precisely how c programs work and what minimum level of content must exist for a program to be able to use libc, I've taken it upon myself to attempt to program primarily in x86 assembly using gas and ld.

As a fun little challenge, I've successfully assembled and linked several programs linked to different self-made dynamic libraries, but I have failed to be able to code a program from scratch to use libc function calls without directly using gcc.

I understand the calling conventions of individual c library functions, and have thoroughly inspected programs compiled out of gcc through use of objdump and readelf, but haven't gotten anywhere as far as what information to include in a gas assembly file and what parameters to invoke in ld to successfully link to libc. Anyone have any insight to this? 

I'm running Linux, on an x86 machine.

How to link a gas assembly program that uses the C standard library with ld without using gcc?

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

文章

问答

视频

学习中心

腾讯云实验室

直播

竞赛

腾讯云代码分析专区

腾讯iOA零信任安全管理系统专区

腾讯云架构师技术同盟交流圈

腾讯云数据库专区

腾讯云顾问专区

腾讯云原生专区

腾讯混元专区

腾讯云TCE专区

腾讯云Lighthouse专区

腾讯云HAI专区

腾讯云Edgeone专区

腾讯云存储专区

腾讯云智能专区

腾讯轻联专区 

腾讯云开发专区

TAPD专区

腾讯轻量云游戏服专区

腾讯云最具价值专家

腾讯云架构师技术同盟

腾讯云创作之星

腾讯云开发者先锋

腾讯云代码助手

云原生构建

TAPD 敏捷项目管理

Cloud Studio

SDK中心

API中心

命令行工具

涵盖代码开发、场景应用、自动测试全流程，助你从零构建专属AI助手

一站式MCP教程库，解锁AI应用新玩法

为了更准确地了解c程序是如何工作的，以及程序要能够使用libc，必须存在什么最低水平的内容，为了更精确地了解c程序的工作，我尝试主要在使用gas和ld的x86程序集中进行编程。作为一个有趣的小挑战，我成功地组装并链接了几个连接到不同的自制动态库的程序，但是我无法从零开始编写一个程序来使用libc函数调用，而不直接使用g...

问如何在不使用gcc的情况下，将使用C标准库的燃气组装程序与ld连接起来？
EN

社区

活动

圈层

关于

腾讯云开发者

热门产品

热门推荐

更多推荐

问如何在不使用gcc的情况下，将使用C标准库的燃气组装程序与ld连接起来？EN

社区

活动

圈层

关于

腾讯云开发者

热门产品

热门推荐

更多推荐

问如何在不使用gcc的情况下，将使用C标准库的燃气组装程序与ld连接起来？
EN