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mono-shlib-cop(1) General Commands Manual mono-shlib-cop(1) NAME mono-shlib-cop - Shared Library Usage Checker SYNOPSIS mono-shlib-cop [OPTIONS]* [ASSEMBLY-FILE-NAME]* OPTIONS -p, --prefixes=PREFIX Mono installation prefixes. This is to find $pre- fix/etc/mono/config. The default is based upon the location of mscorlib.dll, and is normally correct. DESCRIPTION mono-shlib-cop is a tool that inspects a managed assembly looking for erroneous or suspecious usage of shared libraries. The tool takes one or more assembly filenames, and inspects each assem- bly specified. The errors checked for include: * Does the shared library exist? * Does the requested symbol exist within the shared library? The warnings checked for include: * Is the target shared library a versioned library? (Relevant only on Unix systems, not Mac OS X or Windows.) In general, only versioned libraries such as libc.so.6 are present on the user's machine, and efforts to load libc.so will result in a Sys- tem.DllNotFoundException. There are three solutions to this: 1. Require that the user install any -devel packages which provide the unversioned library. This usually requires that the user install a large number of additional packages, complicating the installation process. 2. Use a fully versioned name in your DllImport statements. This requires editing your source code and recompiling whenever you need to target a different version of the shared library. 3. Provide an assembly.config file which contains <dllmap/> ele- ments to remap the shared library name used by your assembly to the actual versioned shared library present on the users system. Mono provides a number of pre-existing <dllmap/> entries, in- cluding ones for libc.so and libX11.so. EXAMPLE The following code contains examples of the above errors and warnings: using System.Runtime.InteropServices; // for DllImport class Demo { [DllImport ("bad-library-name")] private static extern void BadLibraryName (); [DllImport ("libc.so")] private static extern void BadSymbolName (); [DllImport ("libcap.so")] private static extern int cap_clear (IntPtr cap_p); } Bad library name Assuming that the library bad-library-name doesn't exist on your machine, Demo.BadLibraryName will generate an error, as it re- quires a shared library which cannot be loaded. This may be ig- norable; see BUGS Bad symbol name Demo.BadSymbolName will generate an error, as libc.so (remapped to libc.so.6 by mono's $prefix/etc/mono/config file) doesn't contain the function BadSymbolName Unversioned library dependency Assuming you have the file libcap.so , Demo.cap_clear will gen- erate a warning because, while libcap.so could be loaded, lib- cap.so might not exist on the users machine (on FC2, /lib/lib- cap.so is provided by libcap-devel , and you can't assume that end users will have any -devel packages installed). FIXING CODE The fix depends on the warning or error: Bad library names Use a valid library name in the DllImport attribute, or provide a <dllmap/> entry to map your existing library name to a valid library name. Bad symbol names Reference a symbol that actually exists in the target library. Unversioned library dependency Provide a <dllmap/> entry to reference a properly versioned li- brary, or ignore the warning (see BUGS ). DLLMAP ENTRIES Mono looks for an ASSEMBLY-NAME mapping information. For example, with mcs.exe , Mono would read mcs.exe.config , and for Mono.Posix.dll , Mono would read Mono.Posix.dll.config The .config file is an XML document containing a top-level <configura- tion/> section with nested <dllmap/> entries, which contains dll and target attributes. The dll attribute should contain the same string used in your DllImport attribute value, and the target attribute speci- fies which shared library mono should actually load at runtime. A sample .config file is: <configuration> <dllmap dll="gtkembedmoz" target="libgtkembedmoz.so" /> </configuration> BUGS * Only DllImport entries are checked; the surrounding IL is ig- nored. Consequently, if a runtime check is performed to choose which shared library to invoke, an error will be reported even though the specified library is never used. Consider this code: using System.Runtime.InteropServices; // for DllImport class Beep { [DllImport ("kernel32.dll")] private static extern int Beep (int dwFreq, int dwDuration); [DllImport ("libcurses.so")] private static extern int beep (); public static void Beep () { if (System.IO.Path.DirectorySeparatorChar == '\\') { Beep (750, 300); } else { beep (); } } } If mono-shlib-cop is run on this assembly, an error will be re- ported for using kernel32.dll , even though kernel32.dll will never be used on Unix platforms. * mono-shlib-cop currently only examines the shared library file extension to determine if a warning should be generated. A .so extension will always generate a warning, even if the .so is not a symlink, isn't provided in a -devel package, and there is no versioned shared library (possible examples including /usr/lib/libtcl8.4.so, /usr/lib/libubsec.so, etc.). Consequently, warnings for any such libraries are useless, and incorrect. Windows and Mac OS X will never generate warnings, as these platforms use different shared library extensions. MAILING LISTS Visit http://lists.ximian.com/mailman/listinfo/mono-devel-list for de- tails. WEB SITE Visit http://www.mono-project.com for details mono-shlib-cop(1)
NAME | SYNOPSIS | OPTIONS | DESCRIPTION | EXAMPLE | FIXING CODE | DLLMAP ENTRIES | BUGS | MAILING LISTS | WEB SITE
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