Fixed OSX compatibility

Author: imrivera

README.md

@@ -1,15 +1,14 @@
 Overview
 --------
-This script downloads and compiles tcpdump for use on Android devices.
+This script downloads and compiles tcpdump for use on Android devices. It works on Linux and OSX.
 
 It creates PIE (Position Independant Executable) files, so they also work on Lollipop and Marshmallow.
 
 How to use
 ----------
 Install the latest [Android NDK](http://developer.android.com/ndk/downloads/index.html) then:
 
-    export NDK=/path/to/ndk
-    ./build-android-tcpdump
+    ./build-android-tcpdump -n /path/to/ndk
 
 Options
 -------

build-android-tcpdump

@@ -112,7 +112,7 @@ download_file() {
     local URL="$1"
     if [ "${DOWNLOADER}" = "wget" ]; then
         wget "${URL}"
-    elif ["${DOWNLOADER}" = "curl"]; then
+    elif [ "${DOWNLOADER}" = "curl" ]; then
         curl -O "${URL}"
     fi
     if [ $? -ne 0 ]; then
@@ -205,7 +205,7 @@ check_compiler_tools() {
     CC=""
     COMPILERS=$(find "${NDK}/toolchains/${toolchain_dir}/prebuilt" -type f -name "*-gcc")
     for compiler in $COMPILERS; do
-        echo -n "Testing ${compiler}... "
+        printf "Testing ${compiler}... "
         $compiler --version >/dev/null 2>&1
         if [ $? -eq 0 ]; then
             echo "OK"
@@ -218,12 +218,30 @@ check_compiler_tools() {
     if [ -z "${CC}" ]; then
         echo "ERROR: Can't find a valid compiler"
     fi
+   
+    RANLIB_TOOL=""
+    RANLIBS=$(find "${NDK}/toolchains/${toolchain_dir}/prebuilt" -type f -name "*-ranlib")
+    for ranlib in $RANLIBS; do
+        printf "Testing ${ranlib}... "
+        $ranlib --version >/dev/null 2>&1
+        if [ $? -eq 0 ]; then
+            echo "OK"
+            RANLIB_TOOL="${ranlib}"
+            break
+        fi
+        echo "NOT VALID"
+    done
+
+    if [ -z "${RANLIB_TOOL}" ]; then
+        echo "ERROR: Can't find a valid ranlib tool"
+    fi
+    
 
     if [ "${SHOULD_STRIP}" = "yes" ]; then
         STRIP_TOOL=""
         local STRIP_TOOLS=$(find "${NDK}/toolchains/${toolchain_dir}/prebuilt" -type f -name "*-strip")
         for strip_tool in $STRIP_TOOLS; do
-            echo -n "Testing ${strip_tool}... "
+            printf "Testing ${strip_tool}... "
             $strip_tool --version >/dev/null 2>&1
             if [ $? -eq 0 ]; then
                 echo "OK"
@@ -367,6 +385,17 @@ for ARCH in ${ARCHS}; do
         exit 4
     fi    
 
+    if [ ! -f libpcap.a ]; then
+        echo "ERROR: lipcap.a not generated"
+        exit 4
+    fi
+
+    ${RANLIB_TOOL} libpcap.a
+    if [ $? -ne 0 ]; then
+        echo "ERROR: Failed executing ${RANLIB_TOOL} on libpcap.a"
+        exit 4
+    fi
+
     echo "Compiling tcpdump for ${ARCH}..."
     cd "${DIR_TCPDUMP}"