made script and finished for read write malloc and calloc

funfail.sh

@@ -0,0 +1,57 @@
+#!/bin/bash
+
+# Check if funfail.so exists, else make it
+if [ ! -f ./funfail.so ]; then
+    echo "funfail.so not found, attempting to build it..."
+    make || { echo "Build failed. Exiting."; exit 1; }
+fi
+
+# Function to display the menu
+display_menu() {
+    echo "Select the function to fail:"
+    echo "1) malloc"
+    echo "2) calloc"
+    echo "3) read"
+    echo "4) write"
+    echo "5) exit"
+    echo -n "Enter your choice [1-5]: "
+}
+
+# Function to get the number of calls after which the function should fail
+get_fail_after_calls() {
+    echo -n "Enter the number of calls after which the function should fail: "
+    read fail_after_calls
+    if ! [[ "$fail_after_calls" =~ ^[0-9]+$ ]] || [ "$fail_after_calls" -le 0 ]; then
+        echo "Invalid input. Please enter a positive integer."
+        exit 1
+    fi
+}
+
+# Display the menu and get user input
+display_menu
+read choice
+
+# Get the number of calls after which the function should fail
+get_fail_after_calls
+
+# Set the environment variables based on user input
+case $choice in
+    1) export FAIL_FUNC="malloc" ;;
+    2) export FAIL_FUNC="calloc" ;;
+    3) export FAIL_FUNC="read" ;;
+    4) export FAIL_FUNC="write" ;;
+    5) exit 0 ;;
+    *) echo "Invalid choice"; exit 1 ;;
+esac
+
+
+# Set the specific environment variable for the chosen function
+case $FAIL_FUNC in
+    "malloc") export MAX_MALLOC_CALLS=$fail_after_calls ;;
+    "calloc") export MAX_CALLOC_CALLS=$fail_after_calls ;;
+    "read") export MAX_READ_CALLS=$fail_after_calls ;;
+    "write") export MAX_WRITE_CALLS=$fail_after_calls ;;
+esac
+
+# Run the user program with its arguments while preloading funfail.so
+LD_PRELOAD=./funfail.so "$@"

src/read.c

@@ -0,0 +1,26 @@
+#include <dlfcn.h>
+#include <errno.h>
+#include <unistd.h>
+#include <stdlib.h>
+
+typedef ssize_t (*f)(int fd, void *buf, size_t count);
+
+ssize_t read(int fd, void *buf, size_t count)
+{
+    static f og_read = NULL;
+    static int calls = 0;
+    const int MAX_CALLS = getenv("MAX_READ_CALLS") ? atoi(getenv("MAX_READ_CALLS")) : -1;
+
+    if (!og_read)
+    {
+        og_read = (f)dlsym(RTLD_NEXT, "read");
+    }
+
+    calls++;
+    if (MAX_CALLS < 0 || calls <= MAX_CALLS)
+    {
+        return og_read(fd, buf, count);
+    }
+    errno = EBADF;
+    return -1;
+}