c - 为什么 C 库链接顺序只在某些系统上很重要？

Question

我的小组正在开发一个程序，该程序使用依赖于 JPEG 库的 JasPer 库。我的同事创建了一个 Makefile，它在构建规则中的 -ljasper 之前列出了 -ljpeg。这在我同事的计算机上运行良好，但无法在我的计算机上构建:

$ make
cc  -DDEBUG compress_image_test.c -o compress_image_test -Wall -ljpeg -ljasper -lm -lcheck
/usr/local/lib/libjasper.a(jpg_dec.o): In function `jpg_decode':
/cots/jasper-1.900.1/src/libjasper/jpg/jpg_dec.c:158: undefined reference to `jpeg_std_error'
/cots/jasper-1.900.1/src/libjasper/jpg/jpg_dec.c:159: undefined reference to `jpeg_CreateDecompress'
/cots/jasper-1.900.1/src/libjasper/jpg/jpg_dec.c:162: undefined reference to `jpeg_stdio_src'
/cots/jasper-1.900.1/src/libjasper/jpg/jpg_dec.c:165: undefined reference to `jpeg_read_header'
/cots/jasper-1.900.1/src/libjasper/jpg/jpg_dec.c:168: undefined reference to `jpeg_start_decompress'
/cots/jasper-1.900.1/src/libjasper/jpg/jpg_dec.c:190: undefined reference to `jpeg_read_scanlines'
/cots/jasper-1.900.1/src/libjasper/jpg/jpg_dec.c:197: undefined reference to `jpeg_finish_decompress'
/cots/jasper-1.900.1/src/libjasper/jpg/jpg_dec.c:200: undefined reference to `jpeg_destroy_decompress'
/usr/local/lib/libjasper.a(jpg_enc.o): In function `jpg_encode':
/cots/jasper-1.900.1/src/libjasper/jpg/jpg_enc.c:284: undefined reference to `jpeg_std_error'
/cots/jasper-1.900.1/src/libjasper/jpg/jpg_enc.c:285: undefined reference to `jpeg_CreateCompress'
/cots/jasper-1.900.1/src/libjasper/jpg/jpg_enc.c:288: undefined reference to `jpeg_stdio_dest'
/cots/jasper-1.900.1/src/libjasper/jpg/jpg_enc.c:294: undefined reference to `jpeg_set_defaults'
/cots/jasper-1.900.1/src/libjasper/jpg/jpg_enc.c:310: undefined reference to `jpeg_set_quality'
/cots/jasper-1.900.1/src/libjasper/jpg/jpg_enc.c:314: undefined reference to `jpeg_default_colorspace'
/cots/jasper-1.900.1/src/libjasper/jpg/jpg_enc.c:317: undefined reference to `jpeg_start_compress'
/cots/jasper-1.900.1/src/libjasper/jpg/jpg_enc.c:324: undefined reference to `jpeg_write_scanlines'
/cots/jasper-1.900.1/src/libjasper/jpg/jpg_enc.c:329: undefined reference to `jpeg_finish_compress'
/cots/jasper-1.900.1/src/libjasper/jpg/jpg_enc.c:330: undefined reference to `jpeg_destroy_compress'
collect2: ld returned 1 exit status
make: *** [compress_image_test] Error 1

两台机器都运行 Ubuntu 12.04。 JasPer 和 JPEG 库是从源代码构建的，而不是通过 apt-get 获得的。

在阅读了另一个堆栈交换帖子 lib dependencies and their order 之后，我尝试更新 makefile 以将 -ljpeg 的顺序交换到 -ljasper 之后。这奏效了。

所以我的问题是，原来的命令在另一台机器上是没问题的，基本上和我的机器是一样的，但是在我的机器上却不行？

5 月 5 日更新:

这些是我可以在我的电脑上找到的相关库文件:

/usr/lib/i386-linux-gnu:

lrwxrwxrwx 1 root root     18 Jun 21  2012 libjasper.so.1 -> libjasper.so.1.0.0
-rw-r--r-- 1 root root 317148 Jan 11  2012 libjasper.so.1.0.0
lrwxrwxrwx 1 root root     16 Nov 22 07:42 libjpeg.so.8 -> libjpeg.so.8.0.2
-rw-r--r-- 1 root root 284436 Nov 22 07:42 libjpeg.so.8.0.2

/usr/local/lib:

-rw-r--r-- 1 root root 1361856 May  2 09:14 libjasper.a
-rwxr-xr-x 1 root root     757 May  2 09:14 libjasper.la
-rw-r--r-- 1 root root 1461672 May  2 09:15 libjpeg.a
-rwxr-xr-x 1 root root     918 May  2 09:15 libjpeg.la
lrwxrwxrwx 1 root root      16 May  2 09:15 libjpeg.so -> libjpeg.so.9.1.0
lrwxrwxrwx 1 root root      16 May  2 09:15 libjpeg.so.9 -> libjpeg.so.9.1.0
-rwxr-xr-x 1 root root  955739 May  2 09:15 libjpeg.so.9.1.0

以及与我同事计算机上存在的相同文件:

/usr/lib/i386-linux-gnu:

lrwxrwxrwx 1 root root     18 Oct 29  2013 libjasper.so.1 -> libjasper.so.1.0.0
-rw-r--r-- 1 root root 317148 Jan 11  2012 libjasper.so.1.0.0
lrwxrwxrwx 1 root root     16 Nov 22 07:42 libjpeg.so.8 -> libjpeg.so.8.0.2
-rw-r--r-- 1 root root 284436 Nov 22 07:42 libjpeg.so.8.0.2

/usr/local/lib:

-rw-r--r-- 1 root root 1320124 Apr 24 16:01 libjasper.a
-rwxr-xr-x 1 root root     750 Apr 24 16:01 libjasper.la
-rw-r--r-- 1 root root 1462456 Apr 24 16:06 libjpeg.a
-rwxr-xr-x 1 root root     918 Apr 24 16:06 libjpeg.la
lrwxrwxrwx 1 root root      16 Apr 24 16:06 libjpeg.so -> libjpeg.so.9.1.0
lrwxrwxrwx 1 root root      16 Apr 24 16:06 libjpeg.so.9 -> libjpeg.so.9.1.0
-rwxr-xr-x 1 root root  955351 Apr 24 16:06 libjpeg.so.9.1.0

据我所知，所有相同的文件和链接都存在于两个系统上。

Answer 1

您可能正在链接静态库。

对于动态库，整个库都包含在链接中，这将使它的所有符号对后面提到的对象可用，而对于静态库，只有那些满足当前未定义的归档成员链接符号，忽略库的其余部分。