From 1fdab16d96de488e57c83ba7656e87c21fc6c86b Mon Sep 17 00:00:00 2001
From: Dan Buch <daniel.buch@gmail.com>
Date: Sat, 16 Apr 2016 15:35:47 -0400
Subject: [PATCH] ex29

---
 lcthw-remnants-2/Makefile  | 10 ++++++---
 lcthw-remnants-2/ex29.c    | 33 ++++++++++++++++++++++++++++
 lcthw-remnants-2/libex29.c | 45 ++++++++++++++++++++++++++++++++++++++
 3 files changed, 85 insertions(+), 3 deletions(-)
 create mode 100644 lcthw-remnants-2/ex29.c
 create mode 100644 lcthw-remnants-2/libex29.c

diff --git a/lcthw-remnants-2/Makefile b/lcthw-remnants-2/Makefile
index b959778..c6e5992 100644
--- a/lcthw-remnants-2/Makefile
+++ b/lcthw-remnants-2/Makefile
@@ -1,14 +1,18 @@
-SHELL=/bin/bash
-CFLAGS=-Wall -g -DNDEBUG
+SHELL = /bin/bash
+CFLAGS = -Wall -g -DNDEBUG -fPIC
+LDLIBS = -ldl
 
 EXERCISES := $(shell ./list-exercises)
 
-all: $(EXERCISES)
+all: $(EXERCISES) libex29.so
 
 ex19: object.o
 
 ex22_main: ex22.o
 
+libex29.so: libex29.o
+	$(CC) -shared -o $@ $<
+
 clean:
 	shopt -s nullglob ; \
 	$(RM) $(EXERCISES) *.o *.a
diff --git a/lcthw-remnants-2/ex29.c b/lcthw-remnants-2/ex29.c
new file mode 100644
index 0000000..ff115c5
--- /dev/null
+++ b/lcthw-remnants-2/ex29.c
@@ -0,0 +1,33 @@
+#include <stdio.h>
+#include "dbg.h"
+#include <dlfcn.h>
+
+typedef int (*lib_function)(const char *data);
+
+
+int main(int argc, char *argv[])
+{
+  int rc = 0;
+  check(argc == 4, "USAGE: ex29 libex29.so function data");
+
+  char *lib_file = argv[1];
+  char *func_to_run = argv[2];
+  char *data = argv[3];
+
+  void *lib = dlopen(lib_file, RTLD_NOW);
+  check(lib != NULL, "Failed to open the library %s: %s", lib_file, dlerror());
+
+  lib_function func = dlsym(lib, func_to_run);
+  check(func != NULL, "Did not find %s function in the library %s: %s", func_to_run, lib_file, dlerror());
+
+  rc = func(data);
+  check(rc == 0, "Function %s return %d for data: %s", func_to_run, rc, data);
+
+  rc = dlclose(lib);
+  check(rc == 0, "Failed to close %s", lib_file);
+
+  return 0;
+
+error:
+  return 1;
+}
diff --git a/lcthw-remnants-2/libex29.c b/lcthw-remnants-2/libex29.c
new file mode 100644
index 0000000..1aafd4f
--- /dev/null
+++ b/lcthw-remnants-2/libex29.c
@@ -0,0 +1,45 @@
+#include <stdio.h>
+#include <ctype.h>
+#include "dbg.h"
+
+
+int print_a_message(const char *msg)
+{
+  printf("A STRING: %s\n", msg);
+
+  return 0;
+}
+
+
+int uppercase(const char *msg)
+{
+  int i = 0;
+
+  // BUG: \0 termination problems
+  for(i = 0; msg[i] != '\0'; i++) {
+    printf("%c", toupper(msg[i]));
+  }
+
+  printf("\n");
+
+  return 0;
+}
+
+int lowercase(const char *msg)
+{
+  int i = 0;
+
+  // BUG: \0 termination problems
+  for(i = 0; msg[i] != '\0'; i++) {
+    printf("%c", tolower(msg[i]));
+  }
+
+  printf("\n");
+
+  return 0;
+}
+
+int fail_on_purpose(const char *msg)
+{
+  return 1;
+}