[Bug libc/5666] when getline fails it still allocates a buffer

[Bug libc/5666] when getline fails it still allocates a buffer

[svoboda at cert dot org]

http://sourceware.org/bugzilla/show_bug.cgi?id=5666

David Svoboda <svoboda at cert dot org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|RESOLVED                    |REOPENED
                 CC|                            |svoboda at cert dot org
         Resolution|INVALID                     |

--- Comment #4 from David Svoboda <svoboda at cert dot org> 2011-12-09 16:18:26 UTC ---
The bug is in the documentation. The info page does not resolve the question of
whether or not getline() fills lineptr with a pointer that must be freed when
it also returns -1. And there are several coding examples that indicate that
the user need not free the pointer.  

In other words, the docs leave the question unresolved, and several online code
samples get the answer wrong.  Here is one:
http://stackoverflow.com/questions/735126/are-there-alternate-implementations-of-gnu-getline-interface

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[Bug libc/5666] when getline fails it still allocates a buffer

[drepper.fsp at gmail dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=5666

Ulrich Drepper <drepper.fsp at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|REOPENED                    |RESOLVED
         Resolution|                            |INVALID

--- Comment #5 from Ulrich Drepper <drepper.fsp at gmail dot com> 2011-12-18 01:46:44 UTC ---
If you want the documentation to be changed send a patch.  This has nothing to
do with this bug.  Don't reopen it.

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[Bug libc/5666] when getline fails it still allocates a buffer

[svoboda at cert dot org]

http://sourceware.org/bugzilla/show_bug.cgi?id=5666

--- Comment #6 from David Svoboda <svoboda at cert dot org> 2012-01-03 21:31:54 UTC ---
Created attachment 6142
  --> http://sourceware.org/bugzilla/attachment.cgi?id=6142
Amended the documentation to reflect getline() behavior during an error

As requested, here is a patch to 'fix' the documentation.

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[Bug libc/5666] when getline fails it still allocates a buffer

[vapier at gentoo dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=5666

Mike Frysinger <vapier at gentoo dot org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |vapier at gentoo dot org

--- Comment #7 from Mike Frysinger <vapier at gentoo dot org> ---
(In reply to David Svoboda from comment #6)

https://sourceware.org/ml/libc-alpha/2014-04/msg00027.html

btw, if you have other pending issues like this, please re-open them for us to
locate/resolve

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[Bug libc/5666] when getline fails it still allocates a buffer

[cvs-commit at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=5666

--- Comment #9 from cvs-commit at gcc dot gnu.org <cvs-commit at gcc dot gnu.org> ---
This is an automated email from the git hooks/post-receive script. It was
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The branch, master has been updated
       via  1c21d115e3e47cd66007341de4bae5c4b0a2d547 (commit)
      from  fcccd51286acbf9c19ac57ab7143e257d58323fd (commit)

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- Log -----------------------------------------------------------------
https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=1c21d115e3e47cd66007341de4bae5c4b0a2d547

commit 1c21d115e3e47cd66007341de4bae5c4b0a2d547
Author: David Svoboda <svoboda@cert.org>
Date:   Wed Apr 2 05:13:02 2014 -0400

    manual: clarify buffer behavior in getline [BZ #5666]

    If the user has requested automatic buffer creation, getline may create
    it and not free things when an error occurs.  That means the user is
    always responsible for calling free() regardless of the return value.

    The current documentation does not explicitly cover this which leaves it
    slightly ambiguous to the reader.  So clarify things.

    URL: https://sourceware.org/bugzilla/show_bug.cgi?id=5666

-----------------------------------------------------------------------

Summary of changes:
 ChangeLog         |    6 ++++++
 manual/stdio.texi |    3 ++-
 2 files changed, 8 insertions(+), 1 deletions(-)

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[Bug libc/5666] when getline fails it still allocates a buffer

[vapier at gentoo dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=5666

--- Comment #8 from Mike Frysinger <vapier at gentoo dot org> ---
(In reply to Mike Frysinger from comment #7)

https://sourceware.org/git/?p=glibc.git;a=commit;h=1c21d115e3e47cd66007341de4bae5c4b0a2d547

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[Bug libc/5666] when getline fails it still allocates a buffer

[fweimer at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=5666

Florian Weimer <fweimer at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
              Flags|                            |security-

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[Bug libc/5666] New: when getline fails it still allocates a buffer

[werner_hahn at yahoo dot de]

This may be a documentation issue.

When passing the getline function a NULL pointer as a buffer it is so kind to 
allocate the needed memory. However when you reach for example EOF and the 
function returns -1 a buffer of length 120 bytes is allocated anyway which must 
be freed manually or else is lost. It took me quite some time to find out why 
valgrind always told me of 120 lost bytes. The documentation does not mention 
this and so I never suspected this function to be the memory leak.

As getline just functions as a wrapper around getdelim the issue should apply 
to that as well.

I give a quick example:

char *line = NULL;
unsigned int count = 0;
count = getline(&line, &count, file_descriptor);
if(count == -1) // now line points to 120 bytes of junk
{
  free(line); // without this free the buffer pointed to by line is lost
  return NULL;
}

-- 
           Summary: when getline fails it still allocates a buffer
           Product: glibc
           Version: 2.3.6
            Status: NEW
          Severity: normal
          Priority: P2
         Component: libc
        AssignedTo: drepper at redhat dot com
        ReportedBy: werner_hahn at yahoo dot de
                CC: glibc-bugs at sources dot redhat dot com


http://sourceware.org/bugzilla/show_bug.cgi?id=5666

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[Bug libc/5666] when getline fails it still allocates a buffer

[drepper at redhat dot com]

------- Additional Comments From drepper at redhat dot com  2008-01-24 21:03 -------
Do not report problems against anything but the current mainline version.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |WORKSFORME


http://sourceware.org/bugzilla/show_bug.cgi?id=5666

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[Bug libc/5666] when getline fails it still allocates a buffer

[werner_hahn at yahoo dot de]

------- Additional Comments From werner_hahn at yahoo dot de  2008-01-25 09:32 -------
By looking at the source it seems the issue is present in the current version 
too.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|RESOLVED                    |REOPENED
         Resolution|WORKSFORME                  |
            Version|2.3.6                       |unspecified


http://sourceware.org/bugzilla/show_bug.cgi?id=5666

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[Bug libc/5666] when getline fails it still allocates a buffer

[drepper at redhat dot com]

------- Additional Comments From drepper at redhat dot com  2008-03-04 18:35 -------
There is nothing wrong with the implementation.  The buffer, when allocated, is
always the callers problem.  The whole concept of getline is to reuse buffers. 
We do not want the getline/getdelim function arbitrarily free the buffer.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|REOPENED                    |RESOLVED
         Resolution|                            |INVALID


http://sourceware.org/bugzilla/show_bug.cgi?id=5666

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