b6590b7f83
The LinkDemo program calls dlopen/dlsym/dlclose to try and load a dyanmic library from /usr/lib. It read a global variable and calls a global function (extern "C" of course :) ). There a few hacks left in the LinkLib dynamic library, however. In order to get the linker to stop complaining, we have to use -nostartfiles -ffreestanding otherwise it will link crt0.o to our shared object, which is definitely not right as the _init function for a main program (that calls main) is not suitable for our lib
72 lines
No EOL
1.9 KiB
C++
72 lines
No EOL
1.9 KiB
C++
#include <AK/String.h>
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#include <dlfcn.h>
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#include <stdio.h>
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int main()
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{
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void* handle = dlopen("/usr/lib/libDynamicLib.so", RTLD_LAZY | RTLD_GLOBAL);
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if (!handle) {
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printf("Failed to dlopen! %s\n", dlerror());
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return 1;
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}
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// Test getting an external variable from the library and read it out
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int* ptr_global = (int*)dlsym(handle, "global_lib_variable");
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if (!ptr_global) {
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printf("Failed to dlsym for \"global_lib_variable\"! %s\n", dlerror());
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return 2;
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}
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printf("Found global lib variable address: %p\n", ptr_global);
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printf("Global lib variable is %d\n", *ptr_global);
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// Test getting a method from the library and calling it
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void (*lib_func)(void) = (void (*)(void))dlsym(handle, "global_lib_function");
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printf("Found global lib function address: %p\n", lib_func);
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if (!lib_func) {
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printf("Failed to dlsym for \"global_lib_function\"! %s\n", dlerror());
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return 2;
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}
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lib_func();
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printf("I think I called my lib function!\n");
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// Test getting a method that takes and returns arugments now
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const char* (*other_func)(int) = (const char* (*)(int))dlsym(handle, "other_lib_function");
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printf("Found other lib function address %p\n", other_func);
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if (!other_func) {
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printf("Failed to dlsym for \"other_lib_function\"! %s\n", dlerror());
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return 2;
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}
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// Call it twice with different arguments
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String formatted_result = other_func(10);
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printf("(%d + %d = %d) %s\n", *ptr_global, 10, *ptr_global + 10, formatted_result.characters());
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*ptr_global = 17;
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formatted_result = other_func(5);
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printf("(%d + %d = %d) %s\n", *ptr_global, 5, *ptr_global + 5, formatted_result.characters());
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int ret = dlclose(handle);
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if (ret < 0) {
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printf("Failed to dlclose! %s\n", dlerror());
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return 3;
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}
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printf("Bye for now!\n");
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return 0;
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} |