gdb 7.5.91 resolves symbolic links when passing argv[0]

[David Kastrup]

I've reported this to the Ubuntu bug tracker, but judging from the
package files, I can't find proof that it has been introduced
downstream.

The Ubuntu problem description is at
<URL:https://bugs.launchpad.net/ubuntu/+source/gdb/+bug/1173562>.  I
copy the description and example here:

    Calling gdb on an executable that is a symbolic link will pass the
    target of the symbolic link rather than the specified link as
    argv[0] to the program.

    As a result, if the program relies on the contents of argv[0] (for
    example, for figuring out paths relative to the executable or making
    decisions based on the name the executable has been called under),
    debugging fails.

Here is an example for a program relying on its argv[0] name:
/usr/bin/latex is a symbolic link to /usr/bin/pdftex, and pdftex loads a
format depending on the name under which it has been called. As a
result,

latex '\stop'

will load the latex.fmt format and finish processing while the same will
fail under gdb since argv[0] is being passed as /usr/bin/pdftex instead
of /usr/bin/latex:

address@hidden:/tmp$ latex '\stop'
This is pdfTeX, Version 3.1415926-2.4-1.40.13 (TeX Live 2012/Debian)
 restricted \write18 enabled.
entering extended mode
LaTeX2e <2011/06/27>
Babel <v3.8m> and hyphenation patterns for english, dumylang, nohyphenation, bu
lgarian, ukrainian, russian, loaded.
No pages of output.
Transcript written on texput.log.

address@hidden:/tmp$ gdb latex
GNU gdb (GDB) 7.5.91.20130417-cvs-ubuntu
Copyright (C) 2013 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law. Type "show copying"
and "show warranty" for details.
This GDB was configured as "i686-linux-gnu".
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>...
Reading symbols from /usr/bin/pdftex...(no debugging symbols found)...done.
(gdb) run '\stop'
Starting program: /usr/bin/pdftex '\stop'
This is pdfTeX, Version 3.1415926-2.4-1.40.13 (TeX Live 2012/Debian)
 restricted \write18 enabled.
entering extended mode
! Undefined control sequence.
 
<*> \stop

?


Thanks for caring!

-- 
David Kastrup