cmake+conan with -DEXIV2_ENABLE_LIBSSH=On is broken on msvc

[clanmills]

cmake/FindSSH.cmake reports being unable to find libssh. There doesn't seem to be any code in conanfile.py to find libssh. It's working OK on MacOS-X because I build using "pure" CMake (no conan) and libssh is install in /usr/local/

The work-around is to not request this feature in v0.27 We can fix this in 0.27.1

...
-- Found ZLIB: C:/Users/rmills/.conan/data/zlib/1.2.11/conan/stable/package/6cc50b139b9c3d27b3e9042d5f5372d327b3a9f7/lib/zlib.lib (found version "1.2.11") 
-- Found CURL: C:/Users/rmills/.conan/data/libcurl/7.60.0/bincrafters/stable/package/ae6191bc1194317ff7cdbc84d4d302ab49975618/lib/libcurl.lib (found version "7.60.0") 
CMake Error at C:/Program Files/CMake/share/cmake-3.12/Modules/FindPackageHandleStandardArgs.cmake:137 (message):
  Could NOT find SSH (missing: SSH_LIBRARY SSH_INCLUDE_DIR)
Call Stack (most recent call first):
  C:/Program Files/CMake/share/cmake-3.12/Modules/FindPackageHandleStandardArgs.cmake:378 (_FPHSA_FAILURE_MESSAGE)
  cmake/FindSSH.cmake:20 (FIND_PACKAGE_HANDLE_STANDARD_ARGS)
  cmake/findDependencies.cmake:23 (find_package)
  CMakeLists.txt:61 (include)


-- Configuring incomplete, errors occurred!
See also "C:/Users/rmills/gnu/github/exiv2/buildserver/build/CMakeFiles/CMakeOutput.log".
See also "C:/Users/rmills/gnu/github/exiv2/buildserver/build/CMakeFiles/CMakeError.log".

[piponazo]

There is not official conan recipe for libssh, neither an official FindSSH.cmake provided by CMake. There is however a conan package for libssh2:

https://bintray.com/bincrafters/public-conan/libssh2%3Abincrafters

I actually never tried to use compile libSSH on Mac or Windows. Let's see if this is something in which exiv2 windows users are interested.

[D4N]

Uh, I thought we were using libssh2 and not libssh? (We could drop libssh support anyway as curl provides that too.) Luis Díaz Más <[email protected]> writes:

…

There is not official conan recipe for libssh, neither an official FindSSH.cmake provided by CMake. There is however a conan package for libssh2: https://bintray.com/bincrafters/public-conan/libssh2%3Abincrafters I actually never tried to use compile libSSH on Mac or Windows. Let's see if this is something in which exiv2 windows users are interested. -- You are receiving this because you are subscribed to this thread. Reply to this email directly or view it on GitHub: #603 (comment)

[piponazo]

Ha! I did not know that.

If we can do the same with libcurl I would vote for dropping one of the dependencies. The less dependencies the better.

[clanmills]

We could just drop this. I tried to use it on the Mac earlier this week and it didn't seem to be working. There were test scripts for this that operation on a (free) AWS node in Singapore. It hasn't been tested for several years and nobody has ever mentioned it in issues or on the forum. If we remove it, it's unlikely to be missed.

I think we should remove the Video and EPS code as well.

However support for http is useful and valuable. That's implemented in two ways. When curl is available, it's used and support http and https. There's a "no thrills" implementation of the http protocol in http.cpp, so all every build of exiv2 supports http. I don't know that ftp and ftps is useful.

[piponazo]

I am always happy to drop things we do not need, specially if they add an external dependency. If you agree, we can keep that code in 0.27 (since it has been already released) and drop it from master.

[clanmills]

I think we should remove several relics from v0.28 (EPS, Video, ftp, ssh).

The product "road-map" is to maintain v0.27 for a couple of years with security fixes. When we arrive at 0.28.0.1 (RC1), we'll publish a list of deprecated features and users will speak up.

The relics (deprecated features) will be in every "dot" edition of Exiv2 0.27. I can list the "deprecated" features in "the dots" to give users plenty of warning.

[piponazo]

I was going to try to use libssh2 after @D4N 's comment, but I think we are using libssh. We have these inclusions:

include/exiv2/ssh.hpp
27:#include <libssh/libssh.h>
28:#include <libssh/sftp.h>

Which are different to the headers provided with libssh2:
https://github.com/libssh2/libssh2/tree/master/include

@clanmills If I understood correctly, CMake can find libssh on Mac if the system package is installed right? I think there is not an issue here ... we do not have a libssh recipe in conan because it does not exist. If somebody wants to use the SSH features, they will need to use a system package or compile the library by their owns.

If you agree with this observation, please close the issue. And please, when you guys have some time, I would like to reminds you that #617 has been open for review for few weeks.

[clanmills]

#617 is on my TODO list. I built it with -DEXIV2_BUILD_VIDEO=On on MacOS-X. I expected warning and didn't get them. It's on my list to investigate other platforms. So, please be sure, #617 has not been forgotten.