main.c   [plain text]

// BUILD:  $CC myzlib.c -dynamiclib -o $BUILD_DIR/override/libz.1.dylib -install_name /usr/lib/libz.1.dylib -compatibility_version 1.0
// BUILD:  $CC main.c  -o $BUILD_DIR/dyld_shared_cache_some_image_overridden.exe -lz
// BUILD:  $DYLD_ENV_VARS_ENABLE $BUILD_DIR/dyld_shared_cache_some_image_overridden.exe
// BUILD:  $CC main.c  -o $BUILD_DIR/dyld_shared_cache_some_image_overridden-no-lz.exe -DNO_LZ
// BUILD:  $DYLD_ENV_VARS_ENABLE $BUILD_DIR/dyld_shared_cache_some_image_overridden-no-lz.exe

// RUN:  ./dyld_shared_cache_some_image_overridden.exe
// RUN:  DYLD_LIBRARY_PATH=$RUN_DIR/override/ ./dyld_shared_cache_some_image_overridden.exe
// RUN:  ./dyld_shared_cache_some_image_overridden-no-lz.exe
// RUN:  DYLD_LIBRARY_PATH=$RUN_DIR/override/ ./dyld_shared_cache_some_image_overridden-no-lz.exe

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <zlib.h>
#include <stdbool.h>

#include <dlfcn.h>
#include <mach-o/dyld_priv.h>

#include "test_support.h"

// The test here is to override libz.1.dylib which is in the dyld cache with our own implementation.
// We then ensure that dyld_shared_cache_some_image_overridden returns the correct value to match whether we took a root

extern const char* zlibVersion();

int main(int argc, const char* argv[], const char* envp[], const char* apple[]) {
    // If we aren't using a shared cache, eg, have DYLD_SHARED_REGION=avoid, then just assume we work
    uuid_t currentCacheUUID;
    if ( !_dyld_get_shared_cache_uuid(currentCacheUUID) ) {
        if (dyld_shared_cache_some_image_overridden())
            FAIL("Overriden but no shared cache ");
        else
            PASS("No shared cache");
    }

#if NO_LZ
    // This run doesn't link lz so instead dlopen's it
    bool expectMyDylib = (getenv("DYLD_LIBRARY_PATH") != NULL);

    void* handle = dlopen("/usr/lib/libz.1.dylib", RTLD_NOLOAD);
    if ( handle != NULL ) {
        // Uh oh.  Someone else has started linking libz so we can't use it as our root any more
        FAIL("libz is hard linked now.  Update test to use a new dylib");
    }

    bool launchedWithOverriddenBinary = dyld_shared_cache_some_image_overridden();

    // Now dlopen libz
    handle = dlopen("/usr/lib/libz.1.dylib", RTLD_LAZY);
    if ( handle == NULL ) {
        FAIL("/usr/lib/libz.1.dylib could not be loaded, %s", dlerror());
    }

    // verify handle has the version symbol
    __typeof(&zlibVersion) versionSymbol = (__typeof(&zlibVersion))dlsym(handle, "zlibVersion");
    if ( versionSymbol == NULL ) {
        FAIL("zlibVersion was not found");
    }

    bool usingMyDylib = (strcmp(versionSymbol(), "my") == 0);

    if ( usingMyDylib != expectMyDylib ) {
        // Not using the right dylib
        FAIL("%s", expectMyDylib ? "my" : "os");
    }

    // Using the right dylib, so now see if we returned the correct value for dyld_shared_cache_some_image_overridden
    if (usingMyDylib) {
        if (!dyld_shared_cache_some_image_overridden()) {
            FAIL("My dylib but not some dylib overridden");
        }
    } else if (!launchedWithOverriddenBinary) {
        // We didn't have a root when we launched, so now we can make sure we do have a root after the dlopen
        // Assume we aren't testing against a root of libz in the system itself...
        if (dyld_shared_cache_some_image_overridden()) {
            FAIL("System dylib was overridden");
        }
    } else {
        // We can't actually be sure of the result here.  There may be other roots on the system so call the API to
        // make sure it doesn't crash, but don't actually check it.
        dyld_shared_cache_some_image_overridden();
    }
#else
    // This run links libz directly
    bool expectMyDylib = (getenv("DYLD_LIBRARY_PATH") != NULL);

    bool usingMyDylib = (strcmp(zlibVersion(), "my") == 0);

    if ( usingMyDylib != expectMyDylib ) {
        // Not using the right dylib
        FAIL("%s", expectMyDylib ? "my" : "os");
    }

    // Using the right dylib, so now see if we returned the correct value for dyld_shared_cache_some_image_overridden
    if (usingMyDylib) {
        if (!dyld_shared_cache_some_image_overridden()) {
            FAIL("My dylib but not some dylib overridden");
        }
    } else {
        // We can't actually be sure of the result here.  There may be other roots on the system so call the API to
        // make sure it doesn't crash, but don't actually check it.
        dyld_shared_cache_some_image_overridden();
    }
#endif
    PASS("%s", expectMyDylib ? "my" : "os");

    return 0;
}