diamond_dependency_3.sh

#! /bin/bash

# case 3:
#
#    main -----------------> libcommon
#        \--- libmiddle ---> libcommon
#
# 1) start main as a daemon
# 2) update libcommon
# 3) rebuild libmiddle
# 4) wait until main dlopens and calls libmiddle.
#
# result: libmiddle compiled against new API, but calls old API

set -e

# install libcommon API 1

cat >libcommon.c <<"_EOF_"
#include <stdio.h>

void libcommon_test(char *caller) {
    printf("libcommon_test V1 called by %s\n",caller);
}
_EOF_
cat >libcommon.h <<'_EOF_'
#define API_VERSION "1"
_EOF_
gcc -shared -fPIC -Wl,-soname=libcommon-1.so -o libcommon-1.so libcommon.c
ln -sf libcommon-1.so libcommon.so

# install libmiddle

cat >libmiddle.c <<_EOF_
#include <stdio.h>
#include "libcommon.h"

extern void libcommon_test(char *caller);

void libmiddle_test(char *caller) {
    printf("libmiddle_test called by %s\n",caller);
    libcommon_test("libmiddle expecting V" API_VERSION " API");
}
_EOF_
gcc -shared -fPIC -Wl,-soname=libmiddle-1.so -o libmiddle-1.so libmiddle.c
ln -sf libmiddle-1.so libmiddle.so

# install main

cat >main.c <<_EOF_
#include <stdio.h>
#include "libcommon.h"
#include <stdlib.h>
#include <unistd.h>
#include <dlfcn.h>

extern void libcommon_test(char *caller);

int main() {
    void *libmiddle;
    void (*libmiddle_test)(char *caller);

    libcommon_test("main expecting V" API_VERSION " API");

    printf("main waiting...\n");
    sleep(3);

    printf("dlopen libmiddle.so\n");

    libmiddle=dlopen("./libmiddle.so", RTLD_LAZY);
    if (libmiddle==0) {
        fprintf(stderr,"./libmiddle.so : %s\n", dlerror());
        exit(1);
    }

    libmiddle_test=dlsym(libmiddle, "libmiddle_test");
    if (libmiddle_test==0) {
        fprintf(stderr, "./libmiddle.so : libmiddle_test : %s\n", dlerror());
        exit(1);
    }

    libmiddle_test("main");
}
_EOF_

gcc -o main -Wl,-rpath=. -L. -lcommon -ldl main.c

echo "########### start main"

./main &
sleep 1

echo "########### update libcommon"

cat >libcommon.c <<"_EOF_"
#include <stdio.h>

void libcommon_test(char *caller) {
    printf("libcommon_test V2 called by %s\n",caller);
}
_EOF_
cat >libcommon.h <<'_EOF_'
#define API_VERSION "2"
_EOF_
gcc -shared -fPIC -Wl,-soname=libcommon-3.so -o libcommon-3.so libcommon.c
ln -sf libcommon-3.so libcommon.so

echo "########### rebuild libmiddle"

gcc -shared -fPIC -Wl,-soname=libmiddle-1.so -o libmiddle-1.so libmiddle.c
ln -sf libmiddle-1.so libmiddle.so

echo "########### wait for main"

wait