qa-ffi: On finding libc on Linux
Posted: Wed Aug 14, 2013 4:58 pm
In a recent newlisp build on Linux by user hartrock (Stephan), the test qa-ffi failed because it couldn't find where libc was located on hartrock's Linux system. hartrock was building on a 64 bit system and qa-ffi was looking for the 32 bit libc (which naturally didn't exist on his system). The discussion was fleshed out a little here: viewtopic.php?f=16&t=4377.
The upshot is that the current expression which establishes the libc pointer is now the following.
But hartrock suggested that the definition might be changed to be more robust ("Works for me (Debian 64-bit), but should be checked for other Linuxes, too"). He's right, of course.
So, here are two methods I found which seem more robust than the current method. I wonder if you Linux gearheads here would scrutinize these.
One method is to ask gcc where libc is located. This method is discussed here: http://stackoverflow.com/questions/9705 ... er#9706172. Here it is implemented.
Another method is to call ldd on the newlisp executable. This resource talks about this: http://mylinuxbook.com/how-to-determine ... ux-system/. Here is that one implemented. It assumes that the user has built the newlisp executable in the build directory.
I've only tested these on an Ubuntu 12.04 system. I favor the first method. Thoughts? Thanks!
The upshot is that the current expression which establishes the libc pointer is now the following.
Code: Select all
(define LIBC (case ostype
("Win32" "msvcrt.dll")
("OSX" "libc.dylib")
("Linux" (if is64bit
"/lib/x86_64-linux-gnu/libc.so.6"
"/lib/i386-linux-gnu/libc.so.6"))
))So, here are two methods I found which seem more robust than the current method. I wonder if you Linux gearheads here would scrutinize these.
One method is to ask gcc where libc is located. This method is discussed here: http://stackoverflow.com/questions/9705 ... er#9706172. Here it is implemented.
Code: Select all
(define LIBC
(case ostype
("Win32" "msvcrt.dll")
("OSX" "libc.dylib")
("Linux"
(letn (libc-name (first (exec "gcc -print-file-name=libc.so"))
libc-filetype (first (exec (string "file -b " libc-name))))
(if (find "ASCII" libc-filetype)
(first (regex "[^ \t]+/libc\\.so\\.*[0-9]*" (read-file libc-name)))
libc-name)))
))
Code: Select all
(define LIBC
(case ostype
("Win32" "msvcrt.dll")
("OSX" "libc.dylib")
("Linux"
(nth 2
(parse
(first
(filter (curry find "libc.so")
(if (ends-with (real-path) "qa-specific-tests")
(exec "ldd ../newlisp")
(exec "ldd ./newlisp")))))))
))