On Wed, 16 Nov 2016, Jim Patterson wrote: > The wall command on AIX supports a "-g" option to limit the message > to a group of users by gid. Add compatibility to the Linux version. A bit more work to this change: 1) numeric gid is no checked to be valid, 2) gid is checked to be withing range of gid_t and 3) --group option is added to bash completion hints 4) add Reviewed-by line. This change is also available from here: git://github.com/kerolasa/lelux-utiliteetit.git wall-group --->8---- From: Jim Patterson <jimp@xxxxxxxxxx> Date: Wed, 16 Nov 2016 12:22:14 -0500 Subject: [PATCH] wall: add --group option The wall command on AIX supports a "-g" option to limit the message to a group of users by gid. Add compatibility to the Linux version. Thanks to Sami Kerola <kerolasa@xxxxxx> for an initial skeleton implementation. Reference: http://www.ibm.com/support/knowledgecenter/ssw_aix_61/com.ibm.aix.cmds6/wall.htm Reviewed-by: Sami Kerola <kerolasa@xxxxxx> Signed-off-by: Jim Patterson <jimp@xxxxxxxxxx> --- bash-completion/wall | 6 ++++- term-utils/wall.1 | 7 +++++ term-utils/wall.c | 76 +++++++++++++++++++++++++++++++++++++++++++++++++++- 3 files changed, 87 insertions(+), 2 deletions(-) diff --git a/bash-completion/wall b/bash-completion/wall index e3145ff..d2fba9a 100644 --- a/bash-completion/wall +++ b/bash-completion/wall @@ -9,13 +9,17 @@ _wall_module() COMPREPLY=( $(compgen -W "seconds" -- $cur) ) return 0 ;; + '-g'|'--group') + COMPREPLY=( $(compgen -A 'group' -- $cur) ) + return 0 + ;; '-h'|'--help'|'-V'|'--version') return 0 ;; esac case $cur in -*) - OPTS="--nobanner --timeout --version --help" + OPTS="--group --nobanner --timeout --version --help" COMPREPLY=( $(compgen -W "${OPTS[*]}" -- $cur) ) return 0 ;; diff --git a/term-utils/wall.1 b/term-utils/wall.1 index 33cd352..a7da195 100644 --- a/term-utils/wall.1 +++ b/term-utils/wall.1 @@ -39,6 +39,8 @@ wall \- write a message to all users .RB [ \-n ] .RB [ \-t .IR timeout ] +.RB [ \-g +.IR group ] .RI [ message " | " file ] .SH DESCRIPTION .B wall @@ -68,6 +70,11 @@ This \fItimeout\fR must be a positive integer. The default value is 300 seconds, which is a legacy from the time when people ran terminals over modem lines. .TP +.BR \-g , " \-\-group " \fIgroup\fR +Limit printing message to members of group defined as a +.I group +argument. The argument can be group name or gid. +.TP .BR \-V , " \-\-version" Display version information and exit. .TP diff --git a/term-utils/wall.c b/term-utils/wall.c index 4ad94d8..9c89f3e 100644 --- a/term-utils/wall.c +++ b/term-utils/wall.c @@ -58,6 +58,9 @@ #include <unistd.h> #include <utmp.h> #include <getopt.h> +#include <sys/types.h> +#include <grp.h> +#include <linux/sysctl.h> #include "nls.h" #include "xalloc.h" @@ -71,6 +74,7 @@ #define TERM_WIDTH 79 #define WRITE_TIME_OUT 300 /* in seconds */ +#define GID_T_MAX (~(gid_t)0) /* Function prototypes */ static char *makemsg(char *fname, char **mvec, int mvecsz, @@ -86,6 +90,7 @@ static void __attribute__((__noreturn__)) usage(FILE *out) fputs(_("Write a message to all users.\n"), out); fputs(USAGE_OPTIONS, out); + fputs(_(" -g, --group <group> only send message to group\n"), out); fputs(_(" -n, --nobanner do not print banner, works only for root\n"), out); fputs(_(" -t, --timeout <timeout> write timeout in seconds\n"), out); fputs(USAGE_SEPARATOR, out); @@ -96,6 +101,63 @@ static void __attribute__((__noreturn__)) usage(FILE *out) exit(out == stderr ? EXIT_FAILURE : EXIT_SUCCESS); } +struct group_workspace { + gid_t requested_group; + int max; + gid_t *groups; +}; + +static gid_t get_group_gid(const char *optarg) +{ + struct group *gr; + uint64_t gid; + + if ((gr = getgrnam(optarg))) + return gr->gr_gid; + gid = strtou64_or_err(optarg, _("invalid group argument")); + if (GID_T_MAX < gid) + errx(EXIT_FAILURE, "%s: %s", _("gid out of range"), optarg); + if (!getgrgid(gid)) + errx(EXIT_FAILURE, "%s: %s", _("unknown gid"), optarg); + return gid; +} + +static struct group_workspace *init_group_workspace(const char *optarg) +{ + struct group_workspace *buf = xmalloc(sizeof(struct group_workspace)); + + buf->requested_group = get_group_gid(optarg); + buf->max = sysconf(_SC_NGROUPS_MAX) + 1; /* room for the primary gid */ + buf->groups = xcalloc(sizeof(gid_t), buf->max); + + return buf; +} + +static int is_gr_member(const char *login, const struct group_workspace *buf) +{ + struct passwd *pw; + int max_groups = buf->max; + int rc; + + pw = getpwnam(login); + if (buf->requested_group == pw->pw_gid) + return TRUE; + + rc = getgrouplist(login, pw->pw_gid, buf->groups, &max_groups); + if (rc < 0) { + /* buffer too small, not sure how this can happen, since + we used sysconf to get the size... */ + errx(EXIT_FAILURE, + _("getgrouplist found more groups than sysconf allows")); + } + while (max_groups >= 0) { + if (buf->requested_group == buf->groups[max_groups]) + return TRUE; + max_groups--; + } + return FALSE; +} + int main(int argc, char **argv) { int ch; @@ -104,6 +166,7 @@ int main(int argc, char **argv) char *p; char line[sizeof(utmpptr->ut_line) + 1]; int print_banner = TRUE; + struct group_workspace *group_buf = NULL; char *mbuf, *fname = NULL; size_t mbufsize; unsigned timeout = WRITE_TIME_OUT; @@ -113,6 +176,7 @@ int main(int argc, char **argv) static const struct option longopts[] = { { "nobanner", no_argument, 0, 'n' }, { "timeout", required_argument, 0, 't' }, + { "group", required_argument, 0, 'g' }, { "version", no_argument, 0, 'V' }, { "help", no_argument, 0, 'h' }, { NULL, 0, 0, 0 } @@ -123,7 +187,7 @@ int main(int argc, char **argv) textdomain(PACKAGE); atexit(close_stdout); - while ((ch = getopt_long(argc, argv, "nt:Vh", longopts, NULL)) != -1) { + while ((ch = getopt_long(argc, argv, "nt:g:Vh", longopts, NULL)) != -1) { switch (ch) { case 'n': if (geteuid() == 0) @@ -136,6 +200,9 @@ int main(int argc, char **argv) if (timeout < 1) errx(EXIT_FAILURE, _("invalid timeout argument: %s"), optarg); break; + case 'g': + group_buf = init_group_workspace(optarg); + break; case 'V': printf(UTIL_LINUX_VERSION); exit(EXIT_SUCCESS); @@ -172,12 +239,19 @@ int main(int argc, char **argv) if (utmpptr->ut_line[0] == ':') continue; + if (group_buf && !is_gr_member(utmpptr->ut_user, group_buf)) + continue; + xstrncpy(line, utmpptr->ut_line, sizeof(utmpptr->ut_line)); if ((p = ttymsg(&iov, 1, line, timeout)) != NULL) warnx("%s", p); } endutent(); free(mbuf); + if (group_buf) { + free(group_buf->groups); + free(group_buf); + } exit(EXIT_SUCCESS); } -- 2.10.2 -- To unsubscribe from this list: send the line "unsubscribe util-linux" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
