rpmReadConfigFiles raises error: terminate called after throwing an instance of 'std::logic_error'

[rwmjones]

Describe the bug
When trying to use librpm to open an old RPM database from RHEL 5.11, I see a weird error:

terminate called after throwing an instance of 'std::logic_error'
  what():  basic_string: construction from null is not valid

To Reproduce
Steps to reproduce the behavior:

(will follow with reproducer once I've worked out how)

Environment

• OS / Distribution: Fedora Rawhide
• Version rpm-libs-5.99.91-3.fc43.x86_64

Additional context
This happens with run from libguestfs tools (eg. virt-inspector).

[rwmjones]

I put the RPM database here: http://oirase.annexia.org/tmp/rpm-issue-3901/

[rwmjones]

According to https://stackoverflow.com/questions/56552148/how-to-fix-terminate-called-after-throwing-an-instance-of-stdlogic-error-wha this error is what you get in C++ if you try to construct a std::string from a NULL pointer or 0 initializer. Why it happens here I still have no idea.

[rwmjones]

Actually, no, this has nothing to do with the RPM database. It actually occurs when calling rpmReadConfigFiles on the RHEL 5.11 config files. I uploaded the config files from this guest to http://oirase.annexia.org/tmp/rpm-issue-3901/

[rwmjones]

Reproducer:

(1) Unpack http://oirase.annexia.org/tmp/rpm-issue-3901/usr-lib-rpm.tar.xz

(2) Compile the following small program, making sure that /var/tmp/rpmrc in the program below points to the rpmrc file unpacked in step (1).

When run it will print:

terminate called after throwing an instance of 'std::logic_error'
  what():  basic_string: construction from null is not valid
Aborted                    (core dumped) ./testrpm

Program follows:

#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <rpm/rpmlib.h>
#include <rpm/header.h>
#include <rpm/rpmts.h>
#include <rpm/rpmdb.h>

int
main (void)
{
  if (rpmReadConfigFiles ("/var/tmp/rpmrc", NULL) == -1)
    fprintf (stderr, "rpmReadConfigFiles: failed, errno=%d\n", errno);

  printf ("exiting ...\n");

  exit (0);
}

[rwmjones]

Stack trace:

#0  __pthread_kill_implementation (threadid=<optimized out>, signo=signo@entry=6, no_tid=no_tid@entry=0) at pthread_kill.c:44
#1  0x00007f711ed5a4b3 in __pthread_kill_internal (threadid=<optimized out>, signo=6) at pthread_kill.c:89
#2  0x00007f711ed0018e in __GI_raise (sig=sig@entry=6) at ../sysdeps/posix/raise.c:26
#3  0x00007f711ece76d0 in __GI_abort () at abort.c:77
#4  0x00007f711e8091b4 in __gnu_cxx::__verbose_terminate_handler () at ../../../../libstdc++-v3/libsupc++/vterminate.cc:95
#5  0x00007f711e81eb9c in __cxxabiv1::__terminate (handler=<optimized out>) at ../../../../libstdc++-v3/libsupc++/eh_terminate.cc:48
#6  0x00007f711e808d3a in std::terminate () at ../../../../libstdc++-v3/libsupc++/eh_terminate.cc:58
#7  0x00007f711e81ee48 in __cxxabiv1::__cxa_throw (obj=<optimized out>, tinfo=0x7f711ea67c98 <typeinfo for std::logic_error>, dest=0x7f711e834b50 <std::logic_error::~logic_error()>) at ../../../../libstdc++-v3/libsupc++/eh_throw.cc:98
#8  0x00007f711e80c356 in std::__throw_logic_error (__s=__s@entry=0x7f711ef5b998 "basic_string: construction from null is not valid") at ../../../../../libstdc++-v3/src/c++11/functexcept.cc:70
#9  0x00007f711eee2867 in std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::basic_string<std::allocator<char> > (this=<optimized out>, __s=<optimized out>, __a=...) at /usr/include/c++/15/bits/basic_string.h:711
#10 rpmSetVarArch (ctx=<optimized out>, var=<optimized out>, val=<optimized out>, arch=<optimized out>) at /usr/src/debug/rpm-5.99.91-3.fc43.x86_64/lib/rpmrc.cc:1386
#11 doReadRC (ctx=ctx@entry=0x7f711ef76d40 <rpmrcCtxAcquire()::_globalCtx>, urlfn=<optimized out>) at /usr/src/debug/rpm-5.99.91-3.fc43.x86_64/lib/rpmrc.cc:524
#12 0x00007f711ef24b4f in rpmReadRC (ctx=0x7f711ef76d40 <rpmrcCtxAcquire()::_globalCtx>, rcfiles=0x4012e8 "/var/tmp/rpm/usr/lib/rpm/rpmrc") at /usr/src/debug/rpm-5.99.91-3.fc43.x86_64/lib/rpmrc.cc:1638
#13 rpmReadConfigFiles (file=<optimized out>, target=<optimized out>) at /usr/src/debug/rpm-5.99.91-3.fc43.x86_64/lib/rpmrc.cc:1665
#14 0x00000000004004b9 in main ()

[pmatilai]

Sounds like some minute detail got lost in translation when converting the related data structures to STL, should be an easy fix.

Thanks for the report and the reproducer!