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我正在尝试在 C 中编译和运行一个简单的“Hello World”程序,但出现了一个奇怪的错误,即某些 C stdlib 函数的多重定义

.c 文件是:

#include <stdio.h>
#include <stdlib.h>

int main(int argc, char **argv) {

  printf("hello world\n");
  return 0;
}

我用来编译和创建可执行文件的命令是:

gcc -Werror -Wall src/main.c -o bin/m.o
gcc -Werror -Wall bin/m.o -o bin/m

编译部分运行良好,但在第二个命令中,我调用 GCC 链接器来创建可执行文件,但出现以下错误:

bin/m.o: In function `_fini':
(.fini+0x0): multiple definition of `_fini'
/usr/lib/gcc/x86_64-linux-gnu/4.6.1/../../../x86_64-linux-gnu/crti.o:(.fini+0x0): first defined here
bin/m.o: In function `__data_start':
(.data+0x0): multiple definition of `__data_start'
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 0 has invalid symbol index 10
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 1 has invalid symbol index 11
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 2 has invalid symbol index 2
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 3 has invalid symbol index 2
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 4 has invalid symbol index 10
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 5 has invalid symbol index 12
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 6 has invalid symbol index 12
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 7 has invalid symbol index 12
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 8 has invalid symbol index 2
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 9 has invalid symbol index 2
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 10 has invalid symbol index 11
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 11 has invalid symbol index 12
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 12 has invalid symbol index 12
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 13 has invalid symbol index 12
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 14 has invalid symbol index 12
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 15 has invalid symbol index 12
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 16 has invalid symbol index 12
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 17 has invalid symbol index 12
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 18 has invalid symbol index 12
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 19 has invalid symbol index 12
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 20 has invalid symbol index 19
/usr/lib/gcc/x86_64-linux-gnu/4.6.1/../../../x86_64-linux-gnu/crt1.o:(.data+0x0): first defined here
bin/m.o: In function `__data_start':
(.data+0x8): multiple definition of `__dso_handle'
/usr/lib/gcc/x86_64-linux-gnu/4.6.1/crtbegin.o:(.data+0x0): first defined here
bin/m.o:(.rodata+0x0): multiple definition of `_IO_stdin_used'
/usr/lib/gcc/x86_64-linux-gnu/4.6.1/../../../x86_64-linux-gnu/crt1.o:             (.rodata.cst4+0x0): first defined here
bin/m.o: In function `_start':
(.text+0x0): multiple definition of `_start'
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_line): relocation 0 has invalid symbol index 2
/usr/lib/gcc/x86_64-linux-gnu/4.6.1/../../../x86_64-linux-gnu/crt1.o:/build/buildd    /eglibc-2.13/csu/../sysdeps/x86_64/elf/start.S:109: first defined here
bin/m.o: In function `_init':
(.init+0x0): multiple definition of `_init'
/usr/lib/gcc/x86_64-linux-gnu/4.6.1/../../../x86_64-linux-gnu/crti.o:(.init+0x0): first     defined here
/usr/lib/gcc/x86_64-linux-gnu/4.6.1/crtend.o:(.dtors+0x0): multiple definition of     `__DTOR_END__'
bin/m.o:(.dtors+0x8): first defined here
/usr/bin/ld: error in bin/m.o(.eh_frame); no .eh_frame_hdr table will be created.
collect2: ld returned 1 exit status

顺便说一句,当我运行带有 bash 执行前缀的 mo 文件时,它工作得很好

从来没有用 C 或任何东西编程过,我正在尝试开始,但这让我退缩了

4

2 回答 2

12

您需要-c在编译步骤中使用,否则您的m.o对象将是完全链接的可执行文件。例子:

gcc -Werror -Wall -c src/main.c -o bin/m.o
gcc -Werror -Wall bin/m.o -o bin/m

如果您的程序不仅仅是由单个翻译单元组成,那么差异将立即显而易见。如果你有file1.cand file2.c,例如:

gcc -c file1.c -o file1.o
gcc -c file2.c -o file2.o
gcc file1.o file2.o -o app

是正确的,而如果您有:

gcc file1.c -o file1.o
gcc file2.c -o file2.o
gcc file1.o file2.o -o app

在您到达最后的链接阶段之前,第一行和第二行都会失败,因为它们会丢失符号。

于 2012-04-07T17:38:55.307 回答
3
gcc -Werror -Wall src/main.c -o bin/m.o
gcc -Werror -Wall bin/m.o -o bin/m

第一个您省略了该-c选项,因此它创建了一个完全链接的可执行文件。ELF 对象的一个​​特点是可执行文件和目标文件之间没有显着差异,因此它是另一个运行的完全有效的输入ld——但是你会得到链接到完整程序中的符号与要链接到的符号冲突新的那一个。

教训:gcc -c只做编译时使用

gcc -Werror -Wall -c src/main.c -o bin/m.o # this needs -c so it only compiles
gcc -Werror -Wall bin/m.o -o bin/m         # this links, so no -c
于 2012-04-07T17:39:23.950 回答