C app and shared library for hooking examples

c/.gitignore

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+/app/app
+/target/libtarget.so

c/app/build.sh

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+#!/usr/bin/bash
+
+if [[ -f ./app ]]; then
+  rm ./app
+fi
+
+clang -I../target/include -L../target/ -ltarget src/app.c -o app

c/app/run.sh

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+#!/usr/bin/bash
+
+LD_LIBRARY_PATH="../target/" ./app "$@"

c/app/src/app.c

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+#include <stdio.h>
+#include <stdlib.h>
+#include "target.h"
+
+int main(int argc, char **argv) {
+  if(argc < 2) {
+    printf("Usage: %s <integer>\n", argv[0]);
+    exit(EXIT_FAILURE);
+  }
+
+  int input = atoi(argv[1]);
+  maybe_say(input);
+
+  exit(EXIT_SUCCESS);
+}

c/target/build.sh

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+#!/usr/bin/bash
+
+if [[ -f ./libtarget.so ]]; then
+  rm ./libtarget.so
+fi
+
+clang -shared -I./include/ ./src/target.c -o ./libtarget.so
+
+# Don't include the local function symbol
+strip -N say_something ./libtarget.so

c/target/include/target.h

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+#pragma once
+
+void maybe_say(int num);

c/target/src/target.c

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+#include <stdio.h>
+#include <stdlib.h>
+#include "target.h"
+
+static void __attribute__((__noinline__)) say_something() {
+  puts("This is really something!\n");
+}
+
+void maybe_say(int num) {
+  if(num == rand()) {
+    say_something();
+  }
+}