Support dynamic loading of external libraries (pre-compiled user-provided functions)

emulation/ngi.c

@@ -2,6 +2,7 @@
 #include <assert.h>
 #include <float.h>
 #include <math.h>
+#include <dlfcn.h>
 
 int server_reduce(FILE * file, ngi_op_t op, ngi_type_t type, void * out_buff, size_t off, size_t size){
   fseek(file, off, SEEK_SET);
@@ -31,3 +32,29 @@ int server_reduce_any_func(FILE * file, void (*func)(int8_t * data, void * out_b
   free(data);
   return 0;
 }
+
+int server_reduce_any_func_lib(FILE * file, char const * libname, char const * funcname, void * out_buff, size_t max_out_data_size, size_t off, size_t size){
+  void *handle;
+  handle = dlopen(libname, RTLD_LAZY);
+  if(! handle){
+    printf("Error %s\n", dlerror());
+    return 1;
+  }
+
+  fseek(file, off, SEEK_SET);
+
+  void (*func)(int8_t * data, void * out_buff, size_t off, size_t size) = dlsym(handle, funcname);
+  if(! func){
+    printf("Error %s\n", dlerror());
+    dlclose(handle);
+    return 1;
+  }
+
+  int8_t * data = malloc(size);
+  fread(data, size, 1, file);
+  func(data, out_buff, off, size);
+  free(data);
+
+  dlclose(handle);
+  return 0;
+}

emulation/ngi.h

@@ -26,5 +26,7 @@ int server_reduce(FILE * file, ngi_op_t op, ngi_type_t type, void * out_buff, si
  */
 int server_reduce_any_func(FILE * file, void (*func)(int8_t * data, void * out_buff, size_t off, size_t size), void * out_buff, size_t max_out_data_size, size_t off, size_t size);
 
+int server_reduce_any_func_lib(FILE * file, char const * libname, char const * funcname, void * out_buff, size_t max_out_data_size, size_t off, size_t size);
+
 
 #endif

test/reduce-ngi-userlib.c

@@ -0,0 +1,25 @@
+#include <string.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <assert.h>
+#include <stdint.h>
+#include <stdbool.h>
+#include <float.h>
+#include <math.h>
+
+/*
+ Extra user library provided
+ */
+
+void reduce_minmax_func_external(int8_t * data_i, void * out_buff, size_t off, size_t size){
+  float * outf = (float*) out_buff;
+  float mi = outf[0];
+  float mx = outf[1];
+  float * data = (float*) data_i;
+  for(size_t i=0; i < size/sizeof(float); i++){
+    mx = data[i] > mx ? data[i]: mx;
+    mi = data[i] < mi ? data[i]: mi;
+  }
+  outf[0] = mi;
+  outf[1] = mx;
+}

test/reduce-ngi.c

@@ -45,7 +45,7 @@ void reduce_minmax_func(int8_t * data_i, void * out_buff, size_t off, size_t siz
   outf[1] = mx;
 }
 
-// alternative using an external function
+// alternative using an internal function
 void reduce_data_func(int size){
   FILE * file = fopen("data.bin", "rb");
   float mx;
@@ -59,10 +59,20 @@ void reduce_data_func(int size){
   fclose(file);
 }
 
+// alternative using an external library function shipped a s lib
+void reduce_data_func_lib(int size){
+  FILE * file = fopen("data.bin", "rb");
+  float minmax[2] = {INFINITY, -INFINITY};
+  server_reduce_any_func_lib(file, "./libreduce-ngi-userlib.so", "reduce_minmax_func_external", minmax, 2* sizeof(float), 0, size*sizeof(float));
+  printf("Using the external library libreduce-ngi-userlib.so provided by the user: Min/Max: %f - %f\n", minmax[0], minmax[1]);
+  fclose(file);
+}
+
 
 int main(){
   int size = 100;
   reduce_data(size);
   reduce_data_func(size);
+  reduce_data_func_lib(size);
   return 0;
 }

test/run.sh

@@ -7,9 +7,11 @@ gcc -Wall -Wextra reduce-traditional.c -o reduce-traditional -g3
 
 
 # Build NGI lib
-gcc -Wall -Wextra ../emulation/ngi.c -shared -fpic -o libngi.so -g3 -I../emulation/
+gcc -Wall -Wextra ../emulation/ngi.c -shared -fpic -o libngi.so -g3 -I../emulation/ -ldl
 # Build client application
 gcc -Wall -Wextra reduce-ngi.c -o reduce-ngi -g3 -I../emulation/ -L. -l ngi -Wl,-rpath=$PWD
+# Build extra user library
+gcc -Wall -Wextra  reduce-ngi-userlib.c  -shared -fpic -o libreduce-ngi-userlib.so -g3
 
 echo "Data generation"
 ./data-gen