Re: [MACTCL] Mach-O ID of Tcl 8.7a3 Library

[Kevan H. <ha...@br...>]

Dear Marc,

Thank you for your attention, responses to your comments below. For other readers, my question is this: Why does the 8.7a3 Tcl library have an absolute path for its LC_ID_DYLIB rather than a relative path?

> To change the LC_ID_DYLIB path with install_name_tool you should use the -id option. 

That does not work, sadly, I get this error:

kevan@KSH5 Tcl % install_name_tool -id \
	@executable_path/../Frameworks/Tcl.framework/Versions/8.6/Tcl Tcl
/Library/Developer/CommandLineTools/usr/bin/install_name_tool: fatal error: the __LINKEDIT segment
does not cover the end of the file (can't be processed) in: Tcl

It looks like the text segment that holds the ID path is not large enough to contain the extended string of the relative path.

> But the otool -L command does *not* display the LC_ID_DYLIB path of a Mach file. 

I assumed the first path returned by -L was the same as the LC_ID_DYLIB of -l, because they are the same path. Apologies for confusion caused by my error. But the LC_ID_DYLIB is indeed equal to the absolute path I gave.

> So what you need to do is to change (or add) an LC_LOAD_DYLIB path in the main executable of your app so that it will do that. 

This would be a change to the Wish executable, this being the only executable that is executed. The Wish executable already has LC_LOAD_DYLIB for Tcl:

Load command 13
           cmd LC_LOAD_DYLIB
       cmdsize 88
          name @executable_path/../Frameworks/Tcl.framework/Versions/8.7/Tcl (offset 24)
    time stamp 2 Wed Dec 31 19:00:02 1969
       current version 8.7.0
compatibility version 8.7.0

When my X.dylib is called, it demands that Wish find the following library, regardless of the LC_LOAD_DYLIB fields present in the Wish executable.

/Library/Frameworks/Tcl.framework/Versions/8.7/Tcl

> I find it a pain to use otool and install_name_tool and that is why I wrote the utility "macher" 

Sounds like a useful thing to have on my hard driver, thank you. I downloaded and tried to change the id of my Tcl library:

kevan@KSH5 8.7 % ~/Desktop/macher set_id @executable_path/../Frameworks/Tcl.framework/Versions/8.7/Tcl Tcl
Could not open mach-o file Tcl

Best, Kevan

-- 
Kevan Hashemi, Electrical Engineer
Physics Department, Brandeis University
http://www.bndhep.net