I am getting a linker error in XCode 3.2 where it claims to not be able to find libs in /usr/lib even though LIBRARY_SEARCH_PATHS = "/usr/lib" and the dylib has been added to the xcode project. The later copy build phase of the project manages to find this file without any problems, but the cannot.
I have tried to scrap the project settings window for a xcconfig setup instead, so may have done something wrong there. Any ideas as to what I am missing?
Note that paths such as /usr/lib are prefixed by your SDK setting, so what you think is /usr/lib may in fact be e.g. /Developer/SDKs/MacOSX10.6.sdk/usr/lib (if your SDK is set to 10.6).
If you want to link to something in /usr/lib and not in /Developer/SDKs/bla/usr/lib you'll need to use full path to the library when linking. Add it to "Other Linker Flags": /usr/lib/somelib.dylib (note that there is no -l in front of the path)
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I am trying to link libssl.a and libcrypto.a static libraries in XCode command line project [under Link Binary With Libraries]. I have included Openssl header files in search path.
Compilation succeeds but execution fails with dyld: Library not loaded: /usr/local/ssl/lib/libcrypto.1.0.0.dylib.
Why does it look for dylib when I am linking it statically? How can this be fixed?
Any help would be appreciable.
Why does it look for dylib when I am linking it statically? How can this be fixed?
Apple's linker uses the dylib or share object if its available, regardless of of your linker flags like -rpath and -Bstatic. They even do it on iOS, where dylib's are not allowed!
Its kind of a well known problem once you know about it :) See, for example, Installing Crypto++ 5.6.2 on Mac OS X. Crypto++ has the same problems with Apple's tools.
The fix is to stop using -L and -l options, and to link the object file or archive directly. An archive is just a collection of object files, so you can use them interchangeably.
To specify the object files or archives for the linker, see Linking to an object file. Under Xcode, you add the fully specified archive name (like /usr/local/openssl-ios/lib/libcrypto.a) to Other Linker Flags (the OTHER_LDFLAGS Xcode option).
When adding the full archive to OTHER_LDFLAGS, I believe you just add it verbatim without any switches, like -l or -L. You may need -Wl (-Wl,/usr/local/openssl-ios/lib/libcrypto.a), but you don't use -l (-l/usr/local/openssl-ios/lib/libcrypto.a).
You use -Wl when the option is passed through the compiler driver to the linker. If the linker is invoked directly, then you don't need -Wl and should not use it.
A second option is to set GCC_LINK_WITH_DYNAMIC_LIBRARIES to YES. Apple does not appear to document it in Xcode Build Setting Reference, but its clearly under my copy of Xcode. See How to link a static library for iOS on Stack Overflow.
I seem to recall having problems with this in the past. Its one of those things that should work in theory, but does not work in practice.
A third option is to remove the dylib or shared object from all paths used under Xcode so Xcode does not accidentally find it when using -lcrypto.
A fourth option is use allow dynamic linking, but execute the program with DYLD_LIBRARY_PATH. Its OS X's equivalent to LD_LIBRARY_PATH, and ensures your copy of OpenSSL is loaded (like 1.0.2), and not the system's version of OpenSSL (0.9.8).
But I don't like this option because it requires users of your software to do something.
Another possibility due to the message dyld: Library not loaded: /usr/local/ssl/lib/libcrypto.1.0.0.dylib is to code sign your copy of the library. Its a little odd its found but not loaded, so I'm going to toss this out there in case its OS X's Code Signing or Gatekeeper Service...
To code sign your copy of the library under the MAC Developer program, just:
codesign -fs "Johnny Developer" /usr/local/ssl/lib/libcrypto.so
I am a noob and am having an issue with linker flags.
I tried building my own ssh2 libraries, and then afterwards I cloned a git repository with a project in the libraries already built.
Before I downloaded the compiled binaries, I was building with gcrypt and added the -lgrcrypt library to the other linker flags.
With this new library set that I am using, I no longer require gycrpt and so I removed the linker flags. However that did not clear the linker options. I am still getting all of the old linker flags in spite of clearing them in the project properties.
The error shows that the -lgrypt is still being processed as a linker flag:
-no_implicit_dylibs -mios-simulator-version-min=6.0 -lgcrypt
How can I reset the linker flags to what they were?
Thanks in advance
well i presume you have checked the flags and removed the path for that lib in your target level of the project, and also have clean the build and removed the previouse builds from organizer and inside xcode, and also have reset your simulator, and also have checked the project folder on your computer and removed that lib from the library folder of the project. these are the necessary steps and if you have done all of these then i cant think of anything else other than port your code to a new project and try to compile again. good luck my friend.
I have received an old code on the Mac and trying to compile it on OS X 10.6, in the code there are few calls to OpenSSL library (such as SSL_write()) I added the headers (#include ) in those files and check my version of OpenSSL shows me "0.9.8r" (I know Apple has it's own framework for this library crypto' ) but why I get the Link error as this:
sockets::TcpSocket::TryWrite(char const*, unsigned long) in TcpSocket.o
I know the code should compile against this library in /usr/lib but it doesn't, do I missing path or other setting in Xcode?
There are no libraries in /usr/bin. I assume you mean /usr/lib. You generally do not compile against /usr/lib, however. You usually compile against a specific SDK, which has its own copy of /usr/lib and /usr/include. The SDK header files you use is generally passed in the -isysroot parameter. If you're building in Xcode, these settings are set primarily via the "Base SDK" and "OS X Deployment Target." Without more specifics of how you're building, I'm not certain where else to point you, though. In particular, what does the compile and link lines look like for the relevant file?
In Xcode, don't try to link against specific system libraries by path. You should always link against system libraries using the Link Phase panel of the build settings, and selecting from the SDK list of libraries. Selecting specific paths in the Link Phase panel almost always leads to problems.
I have a collection of projects that I'm compiling as dynamic libraries. Each of these .dylibs depend on other various .dylibs that I would like to place in various other directories (i.e. some at the executable path, some at the loader path, some at a fixed path).
When I run otool -L on the compiled libraries, I get a list of paths to those dependencies but I have know idea how those paths are being set/determined. They almost appear pseudo random. I've spent hours messing with the "Build Settings" in Xcode to try and change these paths (w/ #rpath, #executable_path, #loader_path, etc.) but I can't seem to change anything (as checked by running otool -L). I'm not even entirely sure where to add these flags and don't really understand the difference between the following or how to properly use them:
Linking - "Dynamic Library Install Name"
Linking - "Runpath Search Paths"
Linking - "Other Linking Flags"
Search Paths - "Library Search Paths"
When I run install_name_tool -change on the various libraries, I am able to successfully change the run path search paths (again as verified by running otool -L to confirm).
I'm running Xcode 4.2 and I'm very close to giving up and just using a post-build script that runs install_tool_name to make the changes. But its a kludge hack fix and I'd prefer not to do it.
Where can I see how the search/run paths for the dylib dependencies are being set?
Anyone have any ideas on what I might be doing wrong?
Typically, in my dylib's target, I set INSTALL_PATH aka "Installation Directory" to the prefix I want (e.g. #executable_path/../Frameworks).
I leave LD_DYLIB_INSTALL_NAME aka "Dynamic Library Install Name" set to its default value, which is $(DYLIB_INSTALL_NAME_BASE:standardizepath)/$(EXECUTABLE_PATH).
Xcode expands that based on your target's name, so it might end up being #executable_path/../Frameworks/MyFramework.framework/Versions/A/MyFramework, for instance.
The important thing to realize is that the install path is built into the dylib, as part of its build process. Later on, when you link B.dylib that refers to A.dylib, A.dylib's install path is copied into B.dylib. (That's what otool is showing you -- those copied install paths.) So it's best to get the correct install path built into the dylib in the first place.
Before trying to get all the dylibs working together, check each one individually. Build it, then otool -L on the built dylib. The first line for each architecture should be what LD_DYLIB_INSTALL_NAME was showing you.
Once you have that organized, try to get the dylibs linking against each other. It should be much more straightforward.
install_name_tool is very useful for setting the names and paths. Its especially useful if the program runs its self-tests in the build directory, and then things change during a make install. In this case, you can use install_name_tool without the need for a separate build.
install_name_tool is also useful because Apple's LD does not honor rpath linker options like Linux/GCC does. That is, you need to use a different set of commands to set them.
Here's the man page for it. Its included in its entirety because it discusses other options, like -headerpad_max_install_names.
INSTALL_NAME_TOOL(1) INSTALL_NAME_TOOL(1)
NAME
install_name_tool - change dynamic shared library install names
SYNOPSIS
install_name_tool [-change old new ] ... [-rpath old new ] ...
[-add_rpath new ] ... [-delete_rpath new ] ... [-id name] file
DESCRIPTION
Install_name_tool changes the dynamic shared library install names and
or adds, changes or deletes the rpaths recorded in a Mach-O binary.
For this tool to work when the install names or rpaths are larger the
binary should be built with the ld(1) -headerpad_max_install_names
option.
-change old new
Changes the dependent shared library install name old to new in
the specified Mach-O binary. More than one of these options can
be specified. If the Mach-O binary does not contain the old
install name in a specified -change option the option is
ignored.
-id name
Changes the shared library identification name of a dynamic
shared library to name. If the Mach-O binary is not a dynamic
shared library and the -id option is specified it is ignored.
-rpath old new
Changes the rpath path name old to new in the specified Mach-O
binary. More than one of these options can be specified. If
the Mach-O binary does not contain the old rpath path name in a
specified -rpath it is an error.
-add_rpath new
Adds the rpath path name new in the specified Mach-O binary.
More than one of these options can be specified. If the Mach-O
binary already contains the new rpath path name specified in
-add_rpath it is an error.
-delete_rpath old
deletes the rpath path name old in the specified Mach-O binary.
More than one of these options can be specified. If the Mach-O
binary does not contains the old rpath path name specified in
-delete_rpath it is an error.
SEE ALSO
ld(1)
I've set LIBRARY_SEARCH_PATHS to /opt/local/lib, and verified that the library in question is there (I'm linking to GLEW):
$ls /opt/local/lib
libGLEW.1.5.1.dylib libfreetype.a libz.a
libGLEW.1.5.dylib libfreetype.dylib libz.dylib
libGLEW.a libfreetype.la pkgconfig
libGLEW.dylib libz.1.2.3.dylib
libfreetype.6.dylib libz.1.dylib
but Xcode gives me the linker error
library not found for -lGLEW
I'm generating the Xcode project with CMake, so I don't want to explicitly modify the Xcode project (if someone suggests adding it as a framework, or something like that). Xcode recognizes USER_HEADER_SEARCH_PATHS fine (as in this question); why doesn't it work here?
Perhaps adding something like this to your CMakeLists.txt?
find_library(GLEW_LIB GLEW /opt/local/lib)
if(NOT ${GLEW_LIB})
message(FATAL_ERROR "Could not find GLEW")
endif()
target_link_libraries(myprogram ${GLEW_LIB} ...)
Where myprogram is the name of the target executable that needs to link with the library. You would replace the ... with the other libraries you are using on that executable.
This way CMake would handle the library path details for you.
Xcode works on potentially multiple SDK's, so whenever your define these kinds of things (like HEADER_SEARCH_PATHS or LIBRARY_SEARCH_PATHS) the current SDK root is prepended to the actual path that's getting passed to the linker.
So, one way to make this work would be to add your directory to the SDK. For example, assuming you're building with the Mac OS X 10.5 sdk, you could add your opt dir:
ln -s /opt /Developer/SDKs/MacOSX10.5.sdk/opt
Your library would now be found on your system.
If you don't want to do this, then you will have to look at CMake and find out how to get it to generate a library requirement for your actual library (I don't know anything about CMake, so I can't help you there). This is also why you see a difference between USER_HEADER_SEARCH_PATHS and HEADER_SEARCH_PATHS re your other question.
As another option, you could also specify this path with the OTHER_LDFLAGS build variable:
OTHER_LDFLAGS=-L/opt/local/lib
This would cause the linker to search /opt/local/lib as well as its standard paths and wouldn't require you to generate a different project file.