[Scons-users] InstallVersionedLibrary sometimes fails when symlinking

[Andrew C. Morrow]

Here is a complete example demonstrating the problem

SConstruct:

EnsureSConsVersion(2, 3, 0)

AddOption('--prefix',
          dest='prefix',
          type='string',
          nargs=1,
          action='store',
          metavar='DIR',
          help='installation prefix')

env = Environment(
    tools = ["default"],
    PREFIX = GetOption('prefix'))

env.SConscript('src/SConscript', variant_dir='build', exports=['env'])



src/SConscript:

Import('env')

sources = [
    'foo.cpp',
]

headers = [
    'foo.hpp'
]

sharedLibEnv = env.Clone(SHLIBVERSION='0.1.2')
sharedLib = sharedLibEnv.SharedLibrary(
    target='foo',
    source=sources,
)

sharedLibEnv.InstallVersionedLib("$PREFIX/lib", sharedLib)
sharedLibEnv.Install("$PREFIX/include", headers)


src/foo.hpp:

#include <iosfwd>

namespace foo {

    void say_hello(std::ostream& stream);

} // namespace foo


src/foo.cpp:

#include "foo.hpp"

#include <ostream>

namespace foo {

    void say_hello(std::ostream& stream) {
        stream << "Hello, World!\n";
    }

} // namespace foo



OK, so now build the 'install' target, specifying some prefix:

scons --prefix=$(pwd)/install install
scons: Reading SConscript files ...
scons: done reading SConscript files.
scons: Building targets ...
Install file: "build/foo.hpp" as "install/include/foo.hpp"
g++ -o build/foo.os -c -fPIC build/foo.cpp
g++ -o build/libfoo.0.1.2.dylib -dynamiclib -current_version 0.1.2
-compatibility_version 0.1.2 -undefined dynamic_lookup build/foo.os
Install file: "build/libfoo.0.1.2.dylib" as "install/lib/libfoo.0.1.2.dylib"
scons: done building targets.

Now, make a trivial change to foo.cpp to force a relink (like change the
string), and rebuild:

scons --prefix=$(pwd)/install install
scons: Reading SConscript files ...
scons: done reading SConscript files.
scons: Building targets ...
g++ -o build/foo.os -c -fPIC build/foo.cpp
g++ -o build/libfoo.0.1.2.dylib -dynamiclib -current_version 0.1.2
-compatibility_version 0.1.2 -undefined dynamic_lookup build/foo.os
Install file: "build/libfoo.0.1.2.dylib" as "install/lib/libfoo.0.1.2.dylib"
scons: *** [install/lib/libfoo.0.1.2.dylib] File exists
scons: building terminated because of errors.

The build fails while trying to symlink.

Thanks,
Andrew



On Thu, May 23, 2013 at 1:30 PM, Andrew C. Morrow <andrew.c.morrow at gmail.com

> wrote:



>

> Hi -

>

> I've recently been experimenting with the new versioned shared library

> support in SCons 2.3.0, which so far looks really nice, so thanks for that.

>

> I have, I think, found one issue, which is that it appears that if you

>

> - have used InstallVersionedLibrary and produced a target and symlink

> chain in your install directory

> - update a dependency such that the library is rebuilt

> - reinstall

>

> The build fails while attempting to write the symlinks. For my build this

> looks like:

>

> scons: done reading SConscript files.

> scons: Building targets ...

> Install file: "client_build/libfoo.so.2.3.4" as

> "/dev/opt/lib/libfoo.so.2.3.4"

> scons: *** [/dev/opt/lib/libfoo.so.2.3.4] File exists

>

> Running under strace, it is clear that the attempt to create the symlink

> is failing because it already exists in the install directory.

>

> pid 22278] stat("client_build/libfoo.so.2.3.4", {st_mode=S_IFREG|0755,

> st_size=20255704, ...}) = 0

> [pid 22278] utimes("/dev/opt/lib/libfoo.so.2.3.4", {{1369328366, 0},

> {1369328365, 0}}) = 0

> [pid 22278] chmod("/dev/opt/lib/libfoo.so.2.3.4", 0755) = 0

> [pid 22278] stat("client_build/libfoo.so.2.3.4", {st_mode=S_IFREG|0755,

> st_size=20255704, ...}) = 0

> [pid 22278] chmod("/dev/opt/lib/libfoo.so.2.3.4", 0755) = 0

> [pid 22278] symlink("libfoo.so.2.3.4", "/dev/opt/lib/libfoo.so") = -1

> EEXIST (File exists)

>

> I think the same thing can occur in the build directory as well. If I

> remove client_build/libfoo.so.2.3.4 and rebuild, I get a similar error and

> strace:

>

> scons: Building targets ...

> generate_buildinfo(["build/buildinfo.cpp"], ['\n#include

> <string>\n#include <boost/version.hpp>\n\n#include

> "mongo/util/version.h"\n\nnamespace mongo {\n    const char * gitVersion()

> { return "%(git_version)s"; }\n    const char * compiledJSEngine() { return

> "%(js_engine)s"; }\n    const char * allocator() { return "%(allocator)s";

> }\n    const char * loaderFlags() { return "%(loader_flags)s"; }\n    const

> char * compilerFlags() { return "%(compiler_flags)s"; }\n    std::string

> sysInfo() { return "%(sys_info)s BOOST_LIB_VERSION=" BOOST_LIB_VERSION ;

> }\n}  // namespace mongo\n'])

> g++ <library-rebuild>

> scons: *** [client_build/libfoo.so.2.3.4] File exists

>

> strace shows a similar EEXIST error in a call to symlink.

>

> Thanks,

> Andrew

>

>

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