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From: "msebor at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug middle-end/94169] New: warn for modifying getenv() result
Date: Fri, 13 Mar 2020 16:12:03 +0000
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X-Bugzilla-Product: gcc
X-Bugzilla-Component: middle-end
X-Bugzilla-Version: 10.0
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D94169

            Bug ID: 94169
           Summary: warn for modifying getenv() result
           Product: gcc
           Version: 10.0
            Status: UNCONFIRMED
          Severity: enhancement
          Priority: P3
         Component: middle-end
          Assignee: unassigned at gcc dot gnu.org
          Reporter: msebor at gcc dot gnu.org
  Target Milestone: ---

Bug 94157 was caused by modifying the string pointed to by the value return=
ed
from getenv(), which is undefined according to both C and POSIX.  C11 says =
in
7.22.4.8, p4:

  The getenv function returns a pointer to a string associated with the mat=
ched
list member. The string pointed to shall not be modified by the program, but
may be overwritten by a subsequent call to the getenv function.

It would be helpful if GCC issued a warning for attempts to modify the retu=
rned
string.  This could be done by extending -Wstringop-overflow.=