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From: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Newsgroups: gmane.linux.lib.musl.general
Subject: utmp symbol conflict
Date: Thu, 4 Aug 2016 22:28:52 +0200
Organization: Free Electrons
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Hello,

The shellinabox project
(https://github.com/shellinabox/shellinabox) fails to build with musl
due to the following define in musl's utmp.h:

#define utmp utmpx

Indeed shellinabox/launcher.c has the following piece of code
(https://github.com/shellinabox/shellinabox/blob/master/shellinabox/launche=
r.c#L1572) :

    struct utmpx utmpx            =3D utmp->utmpx;
    if (service->useLogin || service->authUser) {
      utmpx.ut_type               =3D LOGIN_PROCESS;
      memset(utmpx.ut_host, 0, sizeof(utmpx.ut_host));
    }

Where "utmp" is of type "struct Utmp *", which is an internal structure
type defined as:

struct Utmp {
  const char   pid[32];
  int          pty;
  int          useLogin;
#ifdef HAVE_UTMPX_H
  struct utmpx utmpx;
#endif
};

Unfortunately, with musl's definition #define utmp utmpx, the line:

	struct utmpx utmpx            =3D utmp->utmpx;

gets turned after pre-processing to:

	struct utmpx utmpx            =3D utmpx->utmpx;

which obviously causes a build failure:

shellinabox/launcher.c: In function =E2=80=98childProcess=E2=80=99:
shellinabox/launcher.c:1576:41: error: invalid type argument of =E2=80=98->=
=E2=80=99 (have =E2=80=98struct utmpx=E2=80=99)
     struct utmpx utmpx            =3D utmp->utmpx;
                                         ^
I don't think the symbol "utmp" as a variable name is reserved, so is
the #define utmp utmpx done by musl really a legal thing to do?

Best regards,

Thomas
--=20
Thomas Petazzoni, CTO, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com