Unix/Linux C動(dòng)態(tài)庫(kù)的使用
動(dòng)態(tài)庫(kù)的生成：
gcc -O -fpic -shared -o share.so share.c
有的gcc版本可以用"-G"替換"-shared"選項(xiàng).
eg.使用動(dòng)態(tài)庫(kù)
#cc -O test.c ./share.so
eg.帶路徑編譯
#cc -O test.c ./lib/share.so
當(dāng)執(zhí)行./a.out時(shí)，操作系統(tǒng)會(huì)自動(dòng)在當(dāng)前目錄lib下查找share.so，若找不到程序?qū)⒈粴?
當(dāng)然也可以通過(guò)更改環(huán)境變量:
#LD_LIBRARY_PATH=./:share
#export LD_LIBRARY_PATH
#./a.out
例程：
dll1.c
|
#include <stdio.h>
int p = 1;
void print()
{
printf("This is the first dll lib provided function: print().\n");
return;
}
|
dll2.c
|
#include <stdio.h>
int p = 2;
void print()
{
printf("This is the second dll lib provided function: print().\n");
return;
}
|
implicit_test.c
|
int main (int argc, char *argv[])
{
print();
return 0;
}
|
explicit_test.c
|
#include <stdio.h>
#include <stdlib.h>
#include <dlfcn.h>
int main(int argc, char *argv[])
{
void *handle; /* pointer of dll lib handle */
void (*pfunc)();
int *p;
handle = dlopen("./dll1.so", RTLD_NOW); /* RTLD_LAZY mode, parsed symbol
when called */
p = (int *)dlsym(handle, "p");
if (p != NULL)
{
printf("p = %d.\n", *p);
}
if ( dlsym(handle, "pp") == NULL ) /* none exist variable pp */
{
printf( "%s\n", dlerror() ); /* print error, and clean */
}
pfunc = (void (*)())dlsym(handle, "print");
if (pfunc != NULL)
{
pfunc();
}
dlclose(handle);
return 0;
}
|
Makefile
|
LIB= -ldl
dll:
gcc -O -fpic -shared -o dll1.so dll1.c
gcc -O -fpic -shared -o dll2.so dll2.c
# some version of gcc supports "-G" instead of "-shared" option
implicit_test:
gcc -O -o implicit_test implicit_test.c ./dll1.so
# argument: ./dll1.so, explicitly tell the os to search dll location.
# if not told path, when running, os will implicitly search at default
# +LD_LIBRARY_PATH=./:dll/
explicit_test:
gcc -O -o explicit_test $(LIB) explicit_test.c
clean:
rm -f dll1.so dll2.so implicit_test explicit_test
|
