Execute program conditionally - cmake

I am opening a file from CMake which will be open in a installed tool in my PC from the following command but the tool is not available in the server which throwing an error during the build.kindly help me to skip that part in server.
COMMAND ${Src_File_gen} -f "${CMAKE_SRC_DIR}/Source.xyz" -g -m ${_VARIANT}

You might want to use find_program before calling the tool. Then wrap the calling CMake command in an if condition only executing when the program was found:
find_program(SRC_FILE_GEN <src_file_gen_exe>)
if(${SRC_FILE_GEN})
COMMAND ${SRC_FILE_GEN} -f "${CMAKE_SRC_DIR}/Source.xyz" -g -m ${_VARIANT}
endif()

Related

How to add and remove some flag to cmake in commandline?

In the command line ubuntu, I want to directly delete a series of flags contained in the source code of the HHVM when using cmake for install HHVM, if available, and add another set of flags to it.
What should I do about this?
please guide me.
for use linker -Wl,--emit-relocs should don't use -E , -s and -c.
example :
$ cmake + (-O3 -fno-reorder-blocks-and-partition -Wl,--emit-relocs)
and
$ cmake - (-E ,-s,-c)

How to run sanitizers on whole project

I'm trying to get familiar with sanitizers as ASAN, LSAN etc and got a lot of useful information already from here: https://developers.redhat.com/blog/2021/05/05/memory-error-checking-in-c-and-c-comparing-sanitizers-and-valgrind
I am able to run all sort of sanitizers on specific files, as shown on the site, like this:
clang -g -fsanitize=address -fno-omit-frame-pointer -g ../TestFiles/ASAN_TestFile.c
ASAN_SYMBOLIZER_PATH=/usr/local/bin/llvm-symbolizer ./a.out >../Logs/ASAN_C.log 2>&1
which generates a log with found issue. Now I would like to extend this to run upon building the project with cmake. This is the command to build it at the moment:
cmake -S . -B build
cd build
make
Is there any way I can use this script with adding the sanitizers, without having to alter the cmakelist.txt file??
For instance something like this:
cmake -S . -B build
cd build
make -fsanitize=address
./a.out >../Logs/ASAN_C.log 2>&1
The reason is that I want to be able to build the project multiple times with different sanitizers (since they cannot be used together) and have a log created without altering the cmakelist.txt file (just want to be able to quickly test the whole project for memory issues instead of doing it for each file created).
You can add additional compiler flags from command line during the build configuration:
cmake -D CMAKE_CXX_FLAGS="-fsanitize=address" -D CMAKE_C_FLAGS="-fsanitize=address" /path/to/CMakeLists.txt
If your CMakeLists.txt is configured properly above should work. If that does not work then try adding flags as environment variable:
cmake -E env CXXFLAGS="-fsanitize=address" CFLAGS="-fsanitize=address" cmake /path/to/CMakeLists.txt

CMake incremental compilation through toolchain upgrade

I am trying to find a way to enable incremental compilation with CMake through a toolchain upgrade. Here is the problematic scenario :
Branch main uses g++-9 (using CMAKE_CXX_COMPILER=g++-9)
A new branch uses g++-10 (using CMAKE_CXX_COMPILER=g++-10)
Commits are happening on both branches
Incremental builds on one branch work fine
Switching to the other branch and explicitly invoking CMake fails
My question is the following : I'm looking for the proper way to make the invocation of CMake succeed and rebuild all the project from scratch when a toolchain change happens.
Here is a script that will make it quick and easy to reproduce the problem. This script requires Docker. It will create folders Sources and Build at the location where it is executed to avoid littering your filesystem. It then creates Dockerfiles to build docker containers with both g++ and cmake. It then creates a dummy Hello World C++ CMake project. Finally, it creates a folder for build artifacts and then executes the build with g++-9 and then g++-10. The second build fails because CMake generates an error.
#!/bin/bash
set -e
mkdir -p Sources
mkdir -p Build
# Creates a script that will be executed inside the docker container to perform builds
cat << EOF > Sources/Compile.sh
cd /Build \
&& cmake /Sources \
&& make \
&& ./IncrementalBuild
EOF
# Creates a Dockerfile that will be used to have both gcc-9 and cmake
cat << EOF > Sources/Dockerfile-gcc9
FROM gcc:9
RUN apt-get update && apt-get install -y cmake
RUN ln -s /usr/local/bin/g++ /usr/local/bin/g++-9
ADD Compile.sh /Compile.sh
RUN chmod +x /Compile.sh
ENTRYPOINT /Compile.sh
EOF
# Creates a Dockerfile that will be used to have both gcc-10 and cmake
cat << EOF > Sources/Dockerfile-gcc10
FROM gcc:10
RUN apt-get update && apt-get install -y cmake
RUN ln -s /usr/local/bin/g++ /usr/local/bin/g++-10
ADD Compile.sh /Compile.sh
RUN chmod +x /Compile.sh
ENTRYPOINT /Compile.sh
EOF
# Creates a dummy C++ program that will be compiled
cat << EOF > Sources/main.cpp
#include <iostream>
int main()
{
std::cout << "Hello World!\n";
}
EOF
# Creates CMakeLists.txt that will be used to compile the dummy C++ program
cat << EOF > Sources/CMakeLists.txt
cmake_minimum_required(VERSION 3.9)
project(IncrementalBuild CXX)
add_executable(IncrementalBuild main.cpp)
set_target_properties(IncrementalBuild PROPERTIES CXX_STANDARD 17)
EOF
# Build the docker images with both Dockerfiles created earlier
docker build -t cmake-gcc:9 -f Sources/Dockerfile-gcc9 Sources
docker build -t cmake-gcc:10 -f Sources/Dockerfile-gcc10 Sources
# Run a build with g++-9
echo ""
echo "### Compiling with g++-9 and then running the result..."
docker run --rm --user $(id -u):$(id -g) -v $(pwd)/Sources:/Sources -v $(pwd)/Build:/Build -e CXX=g++-9 cmake-gcc:9
echo ""
# Run a build with g++-10
echo "### Compiling with g++-10 and then running the result..."
docker run --rm --user $(id -u):$(id -g) -v $(pwd)/Sources:/Sources -v $(pwd)/Build:/Build -e CXX=g++-10 cmake-gcc:10
echo ""
# Print success if we reach this point
echo "SUCCESS!"
I'm looking for the proper way to make the invocation of CMake succeed and rebuild all the project from scratch when a toolchain change happens.
The proper way is to use a fresh binary directory. Either remove the binary directory when changing and let it recreate or just use a separate different directory for each toolchain.
Use Build/gcc10 binary directory for gcc10 build and Build/gcc9 for gcc9 builds.
No need to cd Build and mkdir with nowadays cmake - use cmake -S. -BBuild. Also do not use make - prefer cmake --build Build to let you switch generator later.
"If you change the toolchain, you should start with a fresh build. There are too many things that assume the toolchain doesn’t change and while you may be able to find workarounds which appear to work, I recommend you always use a fresh build tree for a different toolchain. This same logic also applies if you update the existing toolchain in-place (e.g. you update to a newer version of GCC on Linux, a newer version of Xcode on macOS, etc.). CMake queries compiler capabilities and caches the results. If you change the toolchain in a way that CMake can’t catch, then you end up with stale cached capabilities being used for the new/updated toolchain. Please don’t do that." - Craig Scott
So essentially I don't think it's possible. You just need to blow away your build. The best thing you can do is alert users if CMake isn't doing it for you.
Perhaps reply on this also:
https://discourse.cmake.org/t/how-to-change-toolchain-without-breaking-developer-workflows/1166
Or start another discourse.

Why is $PATH different when executing commands via SSH and libssh?

I'm trying to run a command on a remote host via libssh2 as wrapped by the ssh2 Rust crate.
So I would like to run the command cargo build, but when I try to run it via libssh, I get the error:
cargo: command not found
However, when I ssh into the server manually from the command line everything works fine.
I have noticed that the $PATH is different when running ssh from the command line and libssh as well:
for instance when I echo $PATH
ssh gives me:
/home/<user>/.cargo/bin:/usr/share/swift/usr/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/snap/bi
while libssh gives me:
/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games
So it looks like what's happening is that the modifications made to $PATH inside .bashrc and .profile are not making it in when running via libssh.
I also get the same behavior if I run /bin/bash -c "echo ${PATH}"
Why would this be the case, and is there any way to get the same behavior in both these cases?
Please take a look at that question.
TL;DR A login shell first reads /etc/profile and then ~/.bash_profile. A non-login shell reads from /etc/bash.bashrc and then ~/.bashrc.

How to use btgatt-client Command Line Tool

How do I use btgatt-client command line tool? Am I missing something very simple here?
As of Bluez 5.50, it is under in the tools folder (https://git.kernel.org/pub/scm/bluetooth/bluez.git/tree/tools/btgatt-client.c)
But when I try inputting the command, nothing seems to work.
pi#raspberrypi:~ $ btgatt-client
-bash: btgatt-client: command not found
pi#raspberrypi:~ $ sudo btgatt-client
sudo: btgatt-client: command not found
pi#raspberrypi:~ $ btgatt
-bash: btgatt: command not found
pi#raspberrypi:~ $ sudo btgatt
sudo: btgatt: command not found
Bluez sources needs to be compiled with tools support (by default it is enabled), but may be disabled in your raspberry PI build.
You can configure the source using
./configure --enable-tools
If want to cross compile, you may also need to use, "--host"
Or you can directly install the package "bluz-utils" from the package manager repository. For debian,
sudo apt-get install bluez-utils