Question

我正在尝试编译C程序，同时链接APR库。我收到以下错误消息：

cc -g -Wall -pthread -I/usr/local/apr/include/apr-1  -I/usr/local/apr/include/apr-util-1  -L/usr/local/apr/lib -L .aprutil-1 -L .apr-1  devpkg.c bstrlib.o db.o shell.o commands.o   -o devpkg
/tmp/cczC53x5.o: In function `main':
/home/yotam/Dropbox/Development/C/devpkg/devpkg.c:14: undefined reference to `apr_pool_initialize'
/home/yotam/Dropbox/Development/C/devpkg/devpkg.c:15: undefined reference to `apr_pool_create_ex'
/home/yotam/Dropbox/Development/C/devpkg/devpkg.c:29: undefined reference to `apr_getopt_init'
/home/yotam/Dropbox/Development/C/devpkg/devpkg.c:31: undefined reference to `apr_getopt'
db.o: In function `DB_init':
/home/yotam/Development/C/devpkg/db.c:89: undefined reference to `apr_pool_initialize'
/home/yotam/Development/C/devpkg/db.c:90: undefined reference to `apr_pool_create_ex'
/home/yotam/Development/C/devpkg/db.c:93: undefined reference to `apr_dir_make_recursive'
/home/yotam/Development/C/devpkg/db.c:105: undefined reference to `apr_pool_destroy'
/home/yotam/Development/C/devpkg/db.c:109: undefined reference to `apr_pool_destroy'
shell.o: In function `Shell_exec':
/home/yotam/Development/C/devpkg/shell.c:16: undefined reference to `apr_pool_create_ex'
/home/yotam/Development/C/devpkg/shell.c:38: undefined reference to `apr_pool_destroy'
/home/yotam/Development/C/devpkg/shell.c:44: undefined reference to `apr_pool_destroy'
shell.o: In function `Shell_run':
/home/yotam/Development/C/devpkg/shell.c:55: undefined reference to `apr_procattr_create'
/home/yotam/Development/C/devpkg/shell.c:58: undefined reference to `apr_procattr_io_set'
/home/yotam/Development/C/devpkg/shell.c:62: undefined reference to `apr_procattr_dir_set'
/home/yotam/Development/C/devpkg/shell.c:65: undefined reference to `apr_procattr_cmdtype_set'
/home/yotam/Development/C/devpkg/shell.c:68: undefined reference to `apr_proc_create'
/home/yotam/Development/C/devpkg/shell.c:71: undefined reference to `apr_proc_wait'
commands.o: In function `Command_fetch':
/home/yotam/Development/C/devpkg/commands.c:44: undefined reference to `apr_uri_parse'
/home/yotam/Development/C/devpkg/commands.c:48: undefined reference to `apr_fnmatch'
/home/yotam/Development/C/devpkg/commands.c:51: undefined reference to `apr_fnmatch'
/home/yotam/Development/C/devpkg/commands.c:70: undefined reference to `apr_fnmatch'
/home/yotam/Development/C/devpkg/commands.c:78: undefined reference to `apr_dir_make_recursive'
/home/yotam/Development/C/devpkg/commands.c:84: undefined reference to `apr_fnmatch'
/home/yotam/Development/C/devpkg/commands.c:90: undefined reference to `apr_dir_make_recursive'
collect2: error: ld returned 1 exit status
make: *** [devpkg] Error 1

这是我的makefile，它应该能够在不同的计算机上编译，其中PREFIX变量是相对于计算机的位置。（这个程序本质上应该有一天可以移植到任何操作系统。现在我只想能够成功编译它）

PREFIX?=/usr/local
LDFLAGS= -L${PREFIX}/apr/lib -L .aprutil-1 -L .apr-1
CFLAGS=-g -Wall -pthread -I${PREFIX}/apr/include/apr-1  -I${PREFIX}/apr/include/apr-util-1

all: devpkg

devpkg: bstrlib.o db.o shell.o commands.o

install: all \
    install -d $(DESTDIR)/$(PREFIX)/bin/ \
    install devpkg $(DESTDIR)/$(PREFIX)/bin/

clean: 
    rm -f *.o \
    rm -f devpkg \
    rm -rf *.dSYM

我已经离开并自己在文件夹中搜索它，这就是我得到的：

yotam@yotam-HP-ProBook-450://usr$ grep -r apr_pool_initialize .
./local/apr/include/apr-1/apr_pools.h:APR_DECLARE(apr_status_t) apr_pool_initialize(void);
Binary file ./local/apr/lib/libapr-1.so.0.4.6 matches
Binary file ./local/apr/lib/libapr-1.a matches
Binary file ./local/apr/lib/libapr-1.so.0.5.1 matches
Binary file ./local/apr/lib/libapr-1.so.0.4.5 matches
./local/apr/lib/apr.exp:apr_pool_initialize

在我做了之后，我清楚地知道这是一个链接器问题。但是我无法找到执行这个技巧的命令。

提前致谢。

Answer 1

您好像缺少告诉cc要链接的库的链接选项。我不确定您.aprutil-1宏中的.apr-1和LDFLAGS是什么，因为您使用-L指定它们，我会假设它们是目录。

但是，如果您更改行以添加-l选项以指定库，则应该让您更接近。

编辑：因为链接器是单通道工具，所以需要在对象之后列出所有库，因此符号不会被优化掉。 LDLIBS是指定库的宏的典型名称，您可以将它们添加到compile / link命令的末尾，它应该可以工作。

LDFLAGS= -L${PREFIX}/apr/lib -L .aprutil-1 -L .apr-1 LDLIBS= -lapr-1 -laprutil-1

最后两个args告诉链接器要使用哪些库名称（前缀为 lib 并附加 .a ）。 -L选项指定要搜索库的其他目录，它实际上不包含任何内容。

或者，您也可以将LD_LIBRARY_PATH设置为指向库目录。

如果您需要更多帮助调试，可以参考this site（以及其他）作为参考。

Answer 2

尝试用LDLIBS替换LDFLAGS，如：

LDLIBS=-L${PREFIX}/apr/lib -lapr-1 -pthread -laprutil-1

而不是：

LDFLAGS=-L${PREFIX}/apr/lib -lapr-1 -pthread -laprutil-1

这是因为LDFLAGS变量适用于链接器的非库选项，而在这种情况下，您使用的是库。

Make无法找到功能

2 个答案: