Create shared library

Play with shared libs. Building the same library with different
functionalities and loading them at runtime, separately.

Fun way to see how we can change runtime behavior without recompiling
everything.

Signed-off-by: Carlos Maiolino <[email protected]>

5 files changed, 37 insertions, 0 deletions

diff --git a/.gitignore b/.gitignore
index 5761abc..33ec174 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1 +1,3 @@
 *.o
+*.so
+*.a
diff --git a/C/HF/chap8/Makefile b/C/HF/chap8/Makefile
index df3283e..8377c1b 100644
--- a/C/HF/chap8/Makefile
+++ b/C/HF/chap8/Makefile
@@ -13,3 +13,27 @@ bin/libs/xor.o: $(INCLUDE_DIR)/libs/xor.h src/libs/xor.c
 
 bin/libs/encrypt.o: $(INCLUDE_DIR)/libs/encrypt.h src/libs/encrypt.c
 	cc -I $(INCLUDE_DIR) -c src/libs/encrypt.c -o bin/libs/encrypt.o
+
+# Create DSO and PIC versions
+#
+ecatS: bin/libs/libencrypt.a
+	cc -I $(INCLUDE_DIR) -L bin/libs -o bin/ecats src/ecat.c -lencrypts
+
+bin/libs/libencrypts.so: bin/libs/xor-pic.o bin/libs/encrypt-pic.o
+	cc -I $(INCLUDE_DIR) -shared -o bin/libs/libencrypts.so bin/libs/xor-pic.o bin/libs/encrypt-pic.o
+
+# This creates the same lib with a broken encrypt_arr call.
+# We can run the same program passing the different lib at runtime
+# and change the behavior of encrypt_arr at runtime
+bin/broken_libs/libencrypts.so: bin/libs/xor-pic.o bin/libs/encrypt2-pic.o
+	cc -I $(INCLUDE_DIR) -shared -o bin/broken_libs/libencrypts.so bin/libs/xor-pic.o bin/libs/encrypt2-pic.o
+
+
+bin/libs/xor-pic.o: $(INCLUDE_DIR)/libs/xor.h src/libs/xor.c
+	cc -fPIC -I $(INCLUDE_DIR) -c src/libs/xor.c -o bin/libs/xor-pic.o
+
+bin/libs/encrypt-pic.o: $(INCLUDE_DIR)/libs/encrypt.h src/libs/encrypt.c
+	cc -fPIC -I $(INCLUDE_DIR) -c src/libs/encrypt.c -o bin/libs/encrypt-pic.o
+
+bin/libs/encrypt2-pic.o: $(INCLUDE_DIR)/libs/encrypt.h src/libs/encrypt2.c
+	cc -fPIC -I $(INCLUDE_DIR) -c src/libs/encrypt2.c -o bin/libs/encrypt2-pic.o
diff --git a/C/HF/chap8/bin/ecat b/C/HF/chap8/bin/ecat
deleted file mode 100755
index 1167d31..0000000
--- a/C/HF/chap8/bin/ecat
+++ /dev/null
diff --git a/C/HF/chap8/bin/libs/libencrypt.a b/C/HF/chap8/bin/libs/libencrypt.a
deleted file mode 100644
index f609c17..0000000
--- a/C/HF/chap8/bin/libs/libencrypt.a
+++ /dev/null
diff --git a/C/HF/chap8/src/libs/encrypt2.c b/C/HF/chap8/src/libs/encrypt2.c
new file mode 100644
index 0000000..939df8b
--- /dev/null
+++ b/C/HF/chap8/src/libs/encrypt2.c
@@ -0,0 +1,11 @@
+#include <stdio.h>
+#include <libs/encrypt.h>
+
+void encrypt(char *message, encrypt_fn_t encrypt_fn) {
+	encrypt_fn(message);
+}
+
+void encrypt_arr(char *message, encrypt_arr_t fn_arr, int size)
+{
+	printf("BROKEN LIB\n");
+}