Hi Jim, attached is the second version of the patch.
On Thursday 21 of January 2010 13:04:27 Jim Meyering wrote: > >> It would be helpful to say how to determine the appropriate group name. > >> Something like "ls -lg /dev/tty" or > >> $ stat --format %G /dev/tty > >> tty > > > > Do you mean directly in the help string or somewhere else? > > I was thinking of a comment in the .m4 file, > but now that you mention the help string, perhaps that's better. > You choose. Well, let it be a shell comment then. > You're right that we go to extremes to avoid in-functions #ifdefs. > In-function #ifdefs are evil, but so is code duplication. > It's a trade-off. Since this function is so small, > and the fraction of duplicated code would have been so high, > the in-function #ifdef is clearly the lesser evil. It makes sense to me. Kamil
From 55d223fee4900620d7147f134ebebe39fdca90a9 Mon Sep 17 00:00:00 2001 From: Kamil Dudka <[email protected]> Date: Fri, 22 Jan 2010 15:17:19 +0100 Subject: [PATCH] who --mesg now checks the group of TTY devices ... if coreutils is compiled with --with-tty-group. Based on a patch written by Piotr Gackiewicz. Details at https://bugzilla.redhat.com/454261 * src/who.c (is_tty_writable): A new function returning true if a TTY device is writable by the group. Additionally it checks the group to be the same as TTY_GROUP_NAME when compiled with --with-tty-group. * m4/jm-macros.m4: Introduce a new configure option --with-tty-group. * NEWS: Mention the change. --- NEWS | 6 ++++++ THANKS | 1 + m4/jm-macros.m4 | 19 +++++++++++++++++++ src/who.c | 22 +++++++++++++++++++++- 4 files changed, 47 insertions(+), 1 deletions(-) diff --git a/NEWS b/NEWS index 530ff95..0af7b9a 100644 --- a/NEWS +++ b/NEWS @@ -2,6 +2,12 @@ GNU coreutils NEWS -*- outline -*- * Noteworthy changes in release ?.? (????-??-??) [?] +** New features + + who --mesg used to ignore the group of a TTY device when checking if it is + possible to send messages there. Now, if coreutils is compiled with + --with-tty-group[=NAME] configure option, it also compares the group of the + TTY device with NAME (or "tty" if no group is specified). * Noteworthy changes in release 8.4 (2010-01-13) [stable] diff --git a/THANKS b/THANKS index 1207368..d8cdf82 100644 --- a/THANKS +++ b/THANKS @@ -495,6 +495,7 @@ Philippe Schnoebelen [email protected] Phillip Jones [email protected] Piergiorgio Sartor [email protected] Pieter Bowman [email protected] +Piotr Gackiewicz [email protected] Piotr Kwapulinski [email protected] Prashant TR [email protected] Priit Jõerüüt [email protected] diff --git a/m4/jm-macros.m4 b/m4/jm-macros.m4 index 2713827..e0efd29 100644 --- a/m4/jm-macros.m4 +++ b/m4/jm-macros.m4 @@ -144,6 +144,25 @@ AC_DEFUN([coreutils_MACROS], ]) AC_REQUIRE([AM_LANGINFO_CODESET]) + + # configure options --with-tty-group/--without-tty-group + # usually you can determine the group of TTYs by 'stat --format %G /dev/tty' + # omitting this option is equal to --without-tty-group + AC_ARG_WITH([tty-group], + AS_HELP_STRING([--with-tty-group[[[=NAME]]]], + [group used by system for TTYs, "tty" when not specified] + [ (default: do not rely on any group used for TTYs)]), + [tty_group_name=$withval], + [tty_group_name=no]) + + if test "x$tty_group_name" != xno; then + if test "x$tty_group_name" = xyes; then + tty_group_name=tty + fi + AC_MSG_NOTICE([TTY group used by system set to "$tty_group_name"]) + AC_DEFINE_UNQUOTED([TTY_GROUP_NAME], ["$tty_group_name"], + [group used by system for TTYs]) + fi ]) AC_DEFUN([gl_CHECK_ALL_HEADERS], diff --git a/src/who.c b/src/who.c index f71db3b..4110d37 100644 --- a/src/who.c +++ b/src/who.c @@ -37,6 +37,10 @@ #include "hard-locale.h" #include "quote.h" +#ifdef TTY_GROUP_NAME +# include <grp.h> +#endif + /* The official name of this program (e.g., no `g' prefix). */ #define PROGRAM_NAME "who" @@ -308,6 +312,22 @@ print_line (int userlen, const char *user, const char state, free (x_exitstr); } +/* Return true if a terminal device given as PSTAT allows other users + to send messages to; false otherwise */ +static bool +is_tty_writable (const struct stat *pstat) +{ +#ifdef TTY_GROUP_NAME + /* Ensure the group of the TTY device matches TTY_GROUP_NAME, more info at + https://bugzilla.redhat.com/454261 */ + struct group *ttygr = getgrnam (TTY_GROUP_NAME); + if (!ttygr || (pstat->st_gid != ttygr->gr_gid)) + return false; +#endif + + return pstat->st_mode & S_IWGRP; +} + /* Send properly parsed USER_PROCESS info to print_line. The most recent boot time is BOOTTIME. */ static void @@ -346,7 +366,7 @@ print_user (const STRUCT_UTMP *utmp_ent, time_t boottime) if (stat (line, &stats) == 0) { - mesg = (stats.st_mode & S_IWGRP) ? '+' : '-'; + mesg = is_tty_writable (&stats) ? '+' : '-'; last_change = stats.st_atime; } else -- 1.6.2.5
