Cross-compile with external OpenSSL

[zaleksa]

What are the steps to cross-compile macchina.io with built external OpenSSL libraries?

Should I copy OpenSSL header and lib files to macchina.io/platform/openssl directory, or I need to specify INCLUDE and LIB environment variables, or define POCO_EXTERNAL_OPENSSL macro?

Can you provide some example, shell command or similar?

I am going to use ~/armadeus/buildroot/output/build/libopenssl-1.1.1g library.

When I cross-compile macchina.io, following log appears:

In file included from include/Poco/Crypto/Cipher.h:21, from src/Cipher.cpp:15: include/Poco/Crypto/Crypto.h:28:10: fatal error: openssl/opensslv.h: No such file or directory 28 | #include <openssl/opensslv.h> | ^~~~~~~~ compilation terminated.

macchina.io Version macchina-2021.1-release

Compiler and Version gcc --version gcc (Ubuntu 9.3.0-17ubuntu1~20.04) 9.3.0

Operating System and Version System information: Linux (4.19.150) on armv7l

[obiltschnig]

I'd create a custom build configuration file for your platform, then add the search paths for the OpenSSL headers and libraries to the compiler/linker options.

For example, copy the ARM-Linux configuration file in platform/build/config, then add -I/path/to/openssl/include to CXXFLAGS and -L/path/to/openssl/lib to LINKFLAGS. Then cross-compile using the new build configuration.

make -s -j4 DEFAULT_TARGET=shared_release POCO_CONFIG=ARM-Linux-ExtOpenSSL

It would be good to use environment variables for the OpenSSL directories instead of hardcoding them, e.g. -I$(OPENSSL_DIR)/include

You'd then specify OPENSSL_DIR externally, either as environment variable or when running make.

make -s -j4 DEFAULT_TARGET=shared_release POCO_CONFIG=ARM-Linux-ExtOpenSSL OPENSSL_DIR=/path/to/openssl

[zaleksa]

Thank you for the answer.

I've followed your steps, made config file from existing one and changed following lines:

Compiler and Linker Flags CFLAGS = -std=c99 CFLAGS32 = CFLAGS64 = CXXFLAGS = -Wall -Wno-sign-compare -I$(OPENSSL_DIR)/include CXXFLAGS32 = CXXFLAGS64 = LINKFLAGS = -L$(OPENSSL_DIR) LINKFLAGS32 = LINKFLAGS64 =

Then I invoked make command:

$ make -s -j4 LINKMODE=SHARED DEFAULT_TARGET=shared_release POCO_CONFIG=dg100 OPENSSL_DIR=~/armadeus/buildroot/output/build/libopenssl-1.1.1l

Now compiler can find OpenSSL header files, but linker can not link shared libraries libcrypto.so and libssl.so:

ld: cannot find -lssl ld: cannot find -lcrypto collect2: error: ld returned 1 exit status

These libraries are in directory which I assigned to OPENSSL_DIR, while header files are in OPENSSL_DIR/include.

What am I doing wrong?

Thanks in advance, Aleksandar

[obiltschnig]

Are you sure that the libraries are in $(OPENSSL_DIR) and not in $(OPENSSL_DIR)/lib?

[zaleksa]

I think that libraries are in $(OPENSSL_DIR)

There is no lib subdirectory.

Anyway, I tried to compile with $(OPENSSL_DIR)/lib flag in config file, but it failed again.

[obiltschnig]

Looks like LINKFLAGS is the wrong setting here, as it only applies to linking executables, not shared libraries. Try adding:

SHLIBFLAGS = -L$(OPENSSL_DIR)

or, add/modify at the end of the file:

SYSLIBS  = -L$(OPENSSL_DIR) -lpthread -ldl -lrt

[zaleksa]

I added SHLIBFLAGS = -L$(OPENSSL_DIR) at the end of Compiler and Linker Flags. Now it can compile libPocoCrypto.so (~/macchina.io/platform/lib/Linux/armv7a/).

But new error occured:

• Compiling src/MQTTClient.c (release, shared) src/Base64.c:43:10: fatal error: openssl/bio.h: No such file or directory 43 | #include <openssl/bio.h> | ^~~~~~~ compilation terminated. make[3]: [/home/aleksa/macchina.io/platform/build/rules/compile:72: /home/aleksa/macchina.io/protocols/MQTT/Paho/obj/Linux/armv7a/release_shared/Base64.o] Error 1 make[3]: Waiting for unfinished jobs.... In file included from src/Clients.c:24: src/Clients.h:31:10: fatal error: openssl/ssl.h: No such file or directory 31 | #include <openssl/ssl.h> | ^~~~~~~ compilation terminated.

Those missing headers are in OPENSSL_DIR/include/openssl/ directory.

Please look at config file, maybe I'm missing something: dg100.txt

Steps I took to cross-compile macchina.io are:

$ sudo apt install build-essential libssl-dev python $ make -s -j4 hosttools $ export CROSS_COMPILE=arm-none-linux-gnueabihf $ export PATH=~/armadeus/buildroot/output/host/opt/ext-toolchain/bin/:$PATH $ make -s -j4 LINKMODE=SHARED DEFAULT_TARGET=shared_release POCO_CONFIG=dg100 OPENSSL_DIR=~/armadeus/buildroot/output/build/libopenssl-1.1.1l

$ arm-none-linux-gnueabihf-gcc --version arm-none-linux-gnueabihf-gcc (GNU Toolchain for the A-profile Architecture 10.2-2020.11 (arm-10.16)) 10.2.1 20201103 Copyright (C) 2020 Free Software Foundation, Inc. This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

$ gcc --version gcc (Ubuntu 9.3.0-17ubuntu1~20.04) 9.3.0 Copyright (C) 2019 Free Software Foundation, Inc. This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

NOTE: I do succeed to cross-compile macchina.io but only if I manually copy OpenSSL headers and libs to macchina.io (headers to ~/macchina.io/platform/Crypto/include, libs to ~/macchina.io/platform/lib/Linux/armv7a), which is dirty way, especially for git version control.

Please look at this log file, I'm getting lot of warning messages while compiling V8 engine: compile.log

Thank you in advance Aleksandar

[obiltschnig]

You may also want to add -I$(OPENSSL_DIR)/include to CFLAGS.

[obiltschnig]

Unfortunately you'll have to live with the warnings when compiling V8. Or specifically disable them in your build configuration file by adding -Wnodeprecated-copy to CXXFLAGS.

[zaleksa]

Finally I succeeded to cross compile macchina.io with external OpenSSL libraries.

At first I followed your advice to add -I$(OPENSSL_DIR)/include to CFLAGS and CXXFLAGS, -L$(OPENSSL_DIR) to SHLIBFLAGS or SYSLIBS. This way it compiled without errors.

But, then I saw in 'Darwin-clang-libc++' config file that -I$(OPENSSL_DIR)/include is added to SYSFLAGS, and -L$(OPENSSL_DIR)/lib to SYSLIBS. So I tried this way (omitted /lib) and it compiled.

So finally config file looks like this: DG100.txt

Considering V8 compiling, I can live with the warnings. My concern was if I'm doing something wrong, like using wrong gcc version or similiar. Alongside -Wdeprecated-copy warning, there are few more, like:

-Wclass-memaccess -Wcast-function-type -Wimplicit-fallthrough= -Wdeprecated-declarations -Wstringop-overflow= -Wcpp

So I left all warnings to print out while compiling.

Please advise me if you see some issues considering DG100 config file or V8 compile warnings.

Thank you very much, Aleksandar