Where Am I?

A drop-in two files library to locate the current executable and the current module on the file system.

Supported platforms:

Windows
Linux
Mac
iOS
Android
QNX Neutrino
FreeBSD

Just drop whereami.h and whereami.c into your build and get started. (see also customizing compilation)

Usage

wai_getExecutablePath() returns the path of the enclosing executable
wai_getModulePath() returns the path of the enclosing module

Example usage:

first call int length = wai_getExecutablePath(NULL, 0, NULL); to retrieve the length of the path
allocate the destination buffer with path = (char*)malloc(length + 1);
call wai_getExecutablePath(path, length, &dirname_length) again to retrieve the path
add a terminal NUL character with path[length] = '\0';

Here is the output of the example:

$ make -j -C _gnu-make
$ cp ./bin/mac-x86_64/library.dylib /tmp/
$ ./bin/mac-x86_64/executable --load-library=/tmp/library.dylib

executable path: /Users/gregory/Projects/whereami/bin/mac-x86_64/executable
  dirname: /Users/gregory/Projects/whereami/bin/mac-x86_64
  basename: executable
module path: /Users/gregory/Projects/whereami/bin/mac-x86_64/executable
  dirname: /Users/gregory/Projects/whereami/bin/mac-x86_64
  basename: executable

library loaded
executable path: /Users/gregory/Projects/whereami/bin/mac-x86_64/executable
  dirname: /Users/gregory/Projects/whereami/bin/mac-x86_64
  basename: executable
module path: /private/tmp/library.dylib
  dirname: /private/tmp
  basename: library.dylib
library unloaded

Customizing compilation

You can customize the library's behavior by defining the following macros:

WAI_FUNCSPEC
WAI_PREFIX
WAI_MALLOC
WAI_REALLOC
WAI_FREE

Compiling for Windows

There is a Visual Studio 2015 solution in the _win-vs14/ folder.

Compiling for Linux or Mac

There is a GNU Make 3.81 MakeFile in the _gnu-make/ folder:

$ make -j -C _gnu-make/

Compiling for Mac

See above if you want to compile from command line. Otherwise there is an Xcode project located in the _mac-xcode/ folder.

Compiling for iOS

There is an Xcode project located in the _ios-xcode/ folder.

If you prefer compiling from command line and deploying to a jailbroken device through SSH, use:

$ make -j -C _gnu-make/ binsubdir=ios CC="$(xcrun --sdk iphoneos --find clang) -isysroot $(xcrun --sdk iphoneos --show-sdk-path) -arch armv7 -arch armv7s -arch arm64" postbuild="codesign -s 'iPhone Developer'"

Compiling for Android

You will have to install the Android NDK, and point the $NDK_ROOT environment variable to the NDK path: e.g. export NDK_ROOT=/opt/android-ndk (without a trailing / character).

Next, the easy way is to make a standalone Android toolchain with the following command:

$ $NDK_ROOT/build/tools/make_standalone_toolchain.py --arch=arm --install-dir=/tmp/android-toolchain

Now you can compile the example by running:

$ make -j -C _gnu-make/ libsuffix=.so binsubdir=android CC=/tmp/android-toolchain/bin/arm-linux-androideabi-gcc CXX=/tmp/android-toolchain/bin/arm-linux-androideabi-g++

Depending on whether you compile for an Android version that requires PIE executables, add CFLAGS='-fpie' CXXFLAGS='-fpie' LDFLAGS='-pie' accordingly.

Loading page aligned library straight from APKs is supported. To test, use the following:

$ zip -Z store app bin/android/library.so
$ zipalign -v -f -p 4 ./app.zip ./app.apk

Then copy bin/android/executable and app.apk to your Android device and there launch:

$ ./executable --load-library=app.apk!/bin/android/library.so

If you find this library useful and decide to use it in your own projects please drop me a line @gpakosz.

If you use it in a commercial project, consider using Gittip.

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