Hey there Jeremy!
Thanks for your help! I tried what you wrote me. I've adapted the
CmakeLists.txt you suggested to this:
cmake_minimum_required(VERSION 3.0.2)
project(sshtest)
find_package(OpenSSL)
add_subdirectory("libssh-0.7.5" libssh)
set (srcs sshtest.c)
add_executable(sshtest ${srcs})
target_link_libraries(sshtest ssh)
Which works half way, but make breaks with an error of config.h not
found on every source file of the libssh library that includes that
file. I found that I can work around that by replacing the line
#include "config.h"
with
#include "libssh/config.h"
but that seems bad (to modify the libssh source to make it build in my
setup). Is there an alternative?
Thanks,
Regards,
Thomas K.
2017-09-22 22:56 GMT+02:00 Jeremy Cross <[email protected]>:
> Ideally you'd make your own CMakeLists.txt for your executable, and in it
> you'd call add_directory(<path to libssh's CMakeLists.txt>) so that you can
> get it to search for the dependencies and set the link lines for you.
>
> A CMake tutorial is bigger than I'm willing to take on here, but an untested
> simple starter one could look like this:
>
> cmake_minimum_required(VERSION 3.0.2)
> project(sshtest)
> find_package(OpenSSL)
> add_subdirectory_once("path/to/libssh" libssh)
> set (srcs sshtest.c)
> add_executable(sshtest ${srcs})
> target_link_libraries(sshtest libssh)
>
> -----Original Message-----
> From: Thomas Käfer [mailto:[email protected]]
> Sent: Friday, September 22, 2017 1:41 PM
> To: [email protected]
> Subject: Re: static cross-compiling
>
> thanks for the reply jeremy!
>
> Yes I've found this option and was able to generate a libssh.a file.
> but how do I use this?
>
> $ gcc sshtest.c libssh.a -o sshtest.x64 -static doesn't look very promising
> (see attached log)
>
>
> 2017-09-22 22:33 GMT+02:00 Jeremy Cross <[email protected]>:
>> Sure, there's a WITH_STATIC_LIB option on the cmake.
>>
>> Try something like:
>> cmake -DWITH_EXAMPLES=OFF -DBUILD_SHARED_LIBS=OFF -DWITH_STATIC_LIB=ON
>> -DOPENSSL_ROOT_DIR="<your path here>"
>>
>> -----Original Message-----
>> From: Thomas Käfer [mailto:[email protected]]
>> Sent: Friday, September 22, 2017 1:27 PM
>> To: [email protected]
>> Subject: Re: static cross-compiling
>>
>> I tried to recursively (manually..) follow the errors and install the dev
>> packages and include the libraries with the "-lname" parameter to my gcc
>> line, but this is getting out of hand. It doesn't look like I'll ever reach
>> an end:
>>
>> $ gcc sshtest.c -lssh -lcrypto -lz -lgss -lshishi -ltasn1 -lidn
>> -lgcrypt -o sshtest.x64 -static (output see attached file)
>>
>> there must be some better easier way? I'm more of a java developer and there
>> we have maven or other build systems to pull in requirements for building -
>> can I use cmake or something else to walk those dependency paths for me
>> instead of having to do this manually?
>>
>> 2017-09-21 23:11 GMT+02:00 Jeremy Cross <[email protected]>:
>>> Your output indicates that you are missing symbols during the linking. The
>>> symbol names (like BN_new) are from OpenSSL, which would indicate that you
>>> are not properly including OpenSSL libraries in your linking. Depending on
>>> your configuration there may be other libraries you also need to be linking
>>> in...
>>>
>>> -----Original Message-----
>>> From: Thomas Käfer [mailto:[email protected]]
>>> Sent: Thursday, September 21, 2017 1:25 PM
>>> To: [email protected]
>>> Subject: Re: static cross-compiling
>>>
>>> I'm sorry, I forgot to mention that I did read
>>> http://api.libssh.org/master/libssh_linking.html and tried to put "#define
>>> LIBSSH_STATIC 1" and "#define LIBSSH_STATIC" before my include libssh line
>>> but it didn't seem to make a difference..?
>>>
>>> Ah. okey. I've found this link now:
>>> https://stackoverflow.com/questions/21083052/cross-compiling-for-arm-
>>> w hile-linking-to-libssh-libssh-so-file-not-recognized
>>>
>>> So if that's correct I need to cross-compile libssh and it's dependencies
>>> openssl and zlib for arm first, and can then using those prepared arm lib
>>> binaries compile a static build of my program. I will try to work on that
>>> next. Or have a look "embedded Linux distros like Buildroot, OpenEmbedded
>>> or Embedded Debian Project" to see if I find ready made arm binaries I can
>>> use?
>>>
>>> 2017-09-21 19:06 GMT+02:00 Thomas Käfer <[email protected]>:
>>>> Hello!
>>>>
>>>> I would like to write a program that I can cross-compile for Android
>>>> and OpenWRT devices, that uses libssh to first talk to ssh servers
>>>> and in a later development-stage to each other.
>>>>
>>>> Sadly, I'm not really too experienced in programming C / C++, so
>>>> please bear with me.
>>>>
>>>> I found this tutorial
>>>> http://jensd.be/800/linux/cross-compiling-for-arm-with-ubuntu-16-04-
>>>> l t s which with the additional install of the package
>>>> "libc6-armel-cross"
>>>> enabled me to cross-compile a program that prints "hello world" in a
>>>> shell on my android device.
>>>>
>>>> Next step: After installing the package "libssh-dev" I was able to
>>>> use sample code from
>>>> http://api.libssh.org/master/libssh_tutor_guided_tour.html
>>>> to compile a dynamically linked program that works on my Linux laptop.
>>>>
>>>> Now the step I have been struggling with for the last few hours is
>>>> to compile this sample program that uses libssh in a static manner
>>>> (and once that is accomplished doing so using the "arm-linux-gnueabi-gcc"
>>>> cross-compiler)
>>>>
>>>> So I tried:
>>>> $ gcc sshtest.c -static -lssh
>>>> /usr/lib/gcc/x86_64-linux-gnu/5/../../../x86_64-linux-gnu/libssh.a(misc.c.o):
>>>> In function `ssh_path_expand_tilde':
>>>> (.text+0x87d): warning: Using 'getpwnam' in statically linked
>>>> applications requires at runtime the shared libraries from the glibc
>>>> version used for linking
>>>> /usr/lib/gcc/x86_64-linux-gnu/5/../../../x86_64-linux-gnu/libssh.a(misc.c.o):
>>>> In function `ssh_get_user_home_dir':
>>>> (.text+0x3a): warning: Using 'getpwuid_r' in statically linked
>>>> applications requires at runtime the shared libraries from the glibc
>>>> version used for linking ...
>>>> /usr/lib/gcc/x86_64-linux-gnu/5/../../../x86_64-linux-gnu/libssh.a(gssapi.c.o):
>>>> In function `ssh_packet_userauth_gssapi_token_client':
>>>> (.text+0x1b36): undefined reference to `gss_init_sec_context'
>>>> /usr/lib/gcc/x86_64-linux-gnu/5/../../../x86_64-linux-gnu/libssh.a(gssapi.c.o):
>>>> In function `ssh_packet_userauth_gssapi_token_client':
>>>> (.text+0x1c20): undefined reference to `gss_get_mic'
>>>> collect2: error: ld returned 1 exit status
>>>>
>>>> Then I downloaded the libssh source package and made a static build
>>>> of the library using the ccmake gui to set the static parameter to true.
>>>> With this I tried:
>>>> $ gcc sshtest.c libssh-0.7.5/build/src/libssh.a -lssh
>>>> libssh-0.7.5/build/src/libssh.a(curve25519.c.o): In function
>>>> `ssh_curve25519_build_k':
>>>> curve25519.c:(.text+0x13a): undefined reference to `BN_new'
>>>> curve25519.c:(.text+0x1e9): undefined reference to `BN_bin2bn'
>>>> libssh-0.7.5/build/src/libssh.a(dh.c.o): In function `ssh_get_random':
>>>> ...
>>>> libssh-0.7.5/build/src/libssh.a(bignum.c.o): In function
>>>> `ssh_print_bignum':
>>>> bignum.c:(.text+0x175): undefined reference to `BN_bn2hex'
>>>> bignum.c:(.text+0x1dc): undefined reference to `CRYPTO_free'
>>>> collect2: error: ld returned 1 exit status
>>>>
>>>>
>>>> Now I'm out of ideas or in other words my googling skills are not
>>>> sufficient to find new ones ;) Please help..
>>>> Kind regards,
>>>> Thomas K.
>>>
