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Path: utzoo!attcan!uunet!seismo!sundc!pitstop!sun!amdcad!ames!mailrus!tut.cis.ohio-state.edu!ukma!uflorida!novavax!proxftl!bill
From: bill@proxftl.UUCP (T. William Wells)
Newsgroups: comp.unix.questions,comp.lang.c
Subject: Re: General Unix/C question
Keywords: userid Make su segmentation core
Message-ID: <744@proxftl.UUCP>
Date: 13 Sep 88 01:22:15 GMT
References: <641@jura.tcom.stc.co.uk> <794@philmds.UUCP>
Reply-To: bill@proxftl.UUCP (T. William Wells)
Organization: Proximity Technology, Ft. Lauderdale
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In article <794@philmds.UUCP> leo@philmds.UUCP (Leo de Wit) writes:
: In article <641@jura.tcom.stc.co.uk> john@tcom.stc.co.uk (John Blair) writes:
: |
: |Below is the program I use to run a unix command under the userid of the
: |program owner.
: |However when the command passed is Make with parameters and
: |stdout and stderr file redirection I sometimes get segmentation
: |problems and core dumped.
: |
: |If I "su" as the userid of the program owner
: |and execute the same Make command I do not get segmentation problems.
: |What is wrong with the C program?
: |
: |/* note, this must run with set uid on execution */
: |main(argc,argv)
: | int argc;
: | char * argv[];
: |{
: | setuid(geteuid());
: | setgid(getegid());
: | execvp(argv[1],argv+1);
: |}

:             2) when you start the program the input/output redirection is
: done, perhaps by your shell. This means that these input/output streams
: must be readable/writable by the current uid/gid;

I don't think this is correct.  When a file is opened, you are
given certain access permissions.  These permissions do not
change, even if your uid/gid changes.

---
Bill
novavax!proxftl!bill