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write: stop removing and adding /dev/ in front of tty string 

Add both path and tty name representations of tty's to control structure,
that point to same string beginning from different depths.  This way there
is no need to removing and adding /dev/ in front of tty string all the time.

Secondly this change makes it possible to use of get_terminal_name() from
ttyutils.c.

Signed-off-by: Sami Kerola <kerolasa@iki.fi>
This commit is contained in:
Sami Kerola 2016-05-14 19:39:37 +01:00
parent 50e417c8ad
commit a58b90255c
No known key found for this signature in database
GPG Key ID: A9553245FDE9B739
2 changed files with 39 additions and 43 deletions
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1
term-utils/Makemodule.am
View File

@ -93,6 +93,7 @@ dist_man_MANS += term-utils/write.1
write_SOURCES = term-utils/write.c
write_CFLAGS = $(SUID_CFLAGS) $(AM_CFLAGS)
write_LDFLAGS = $(SUID_LDFLAGS) $(AM_LDFLAGS)
write_LDADD = $(LDADD) libcommon.la
if USE_TTY_GROUP
if MAKEINSTALL_DO_CHOWN

81
term-utils/write.c
View File

@ -64,6 +64,7 @@
#include "closestream.h"
#include "nls.h"
#include "strutils.h"
#include "ttyutils.h"
#include "xalloc.h"
static sig_atomic_t signal_received = 0;
@ -71,9 +72,11 @@ static sig_atomic_t signal_received = 0;
struct write_control {
uid_t src_uid;
const char *src_login;
char *src_tty;
const char *src_tty_path;
const char *src_tty_name;
const char *dst_login;
char dst_tty[PATH_MAX];
char *dst_tty_path;
const char *dst_tty_name;
};
static void __attribute__((__noreturn__)) usage(FILE *out)
@ -98,24 +101,20 @@ static void __attribute__((__noreturn__)) usage(FILE *out)
* check_tty - check that a terminal exists, and get the message bit
* and the access time
*/
static int check_tty(char *tty, int *tty_writeable, time_t *tty_atime, int showerror)
static int check_tty(const char *tty, int *tty_writeable, time_t *tty_atime, int showerror)
{
struct stat s;
char path[PATH_MAX];
if (sizeof(path) < strlen(tty) + 6)
return 1;
sprintf(path, "/dev/%s", tty);
if (stat(path, &s) < 0) {
if (stat(tty, &s) < 0) {
if (showerror)
warn("%s", path);
warn("%s", tty);
return 1;
}
if (getuid() == 0) /* root can always write */
*tty_writeable = 1;
else {
if (getegid() != s.st_gid) {
warnx(_("effective gid does not match group of %s"), path);
warnx(_("effective gid does not match group of %s"), tty);
return 1;
}
*tty_writeable = s.st_mode & S_IWGRP;
@ -139,7 +138,7 @@ static int check_utmp(const struct write_control *ctl)
while ((u = getutent())) {
if (strncmp(ctl->dst_login, u->ut_user, sizeof(u->ut_user)) == 0 &&
strncmp(ctl->dst_tty, u->ut_line, sizeof(u->ut_line)) == 0) {
strncmp(ctl->dst_tty_name, u->ut_line, sizeof(u->ut_line)) == 0) {
res = 0;
break;
}
@ -165,6 +164,7 @@ static void search_utmp(struct write_control *ctl)
struct utmp *u;
time_t best_atime = 0, tty_atime;
int num_ttys = 0, valid_ttys = 0, tty_writeable = 0, user_is_me = 0;
char path[UT_LINESIZE + 6];
utmpname(_PATH_UTMP);
setutent();
@ -173,13 +173,14 @@ static void search_utmp(struct write_control *ctl)
if (strncmp(ctl->dst_login, u->ut_user, sizeof(u->ut_user)) != 0)
continue;
num_ttys++;
if (check_tty(u->ut_line, &tty_writeable, &tty_atime, 0))
sprintf(path, "/dev/%s", u->ut_line);
if (check_tty(path, &tty_writeable, &tty_atime, 0))
/* bad term? skip */
continue;
if (ctl->src_uid && !tty_writeable)
/* skip ttys with msgs off */
continue;
if (strcmp(u->ut_line, ctl->src_tty) == 0) {
if (strcmp(u->ut_line, ctl->src_tty_name) == 0) {
user_is_me = 1;
/* don't write to yourself */
continue;
@ -190,8 +191,9 @@ static void search_utmp(struct write_control *ctl)
valid_ttys++;
if (best_atime < tty_atime) {
best_atime = tty_atime;
xstrncpy(ctl->dst_tty, u->ut_line,
sizeof(ctl->dst_tty));
free(ctl->dst_tty_path);
ctl->dst_tty_path = xstrdup(path);
ctl->dst_tty_name = ctl->dst_tty_path + 5;
}
}
@ -201,14 +203,17 @@ static void search_utmp(struct write_control *ctl)
if (valid_ttys == 0) {
if (user_is_me) {
/* ok, so write to yourself! */
xstrncpy(ctl->dst_tty, ctl->src_tty, sizeof(ctl->dst_tty));
if (!ctl->src_tty_path)
errx(EXIT_FAILURE, _("can't find your tty's name"));
ctl->dst_tty_path = xstrdup(ctl->src_tty_path);
ctl->dst_tty_name = ctl->dst_tty_path + 5;
return;
}
errx(EXIT_FAILURE, _("%s has messages disabled"), ctl->dst_login);
}
if (1 < valid_ttys)
warnx(_("%s is logged in more than once; writing to %s"),
ctl->dst_login, ctl->dst_tty);
ctl->dst_login, ctl->dst_tty_name);
}
/*
@ -243,7 +248,7 @@ static void do_write(const struct write_control *ctl)
struct passwd *pwd;
time_t now;
struct tm *tm;
char path[PATH_MAX], *host, line[512];
char *host, line[512];
struct sigaction sigact;
/* Determine our login name(s) before the we reopen() stdout */
@ -254,11 +259,8 @@ static void do_write(const struct write_control *ctl)
if ((login = getlogin()) == NULL)
login = pwuid;
if (sizeof(path) < strlen(ctl->dst_tty) + 6)
errx(EXIT_FAILURE, _("tty path %s too long"), ctl->dst_tty);
snprintf(path, sizeof(path), "/dev/%s", ctl->dst_tty);
if ((freopen(path, "w", stdout)) == NULL)
err(EXIT_FAILURE, "%s", path);
if ((freopen(ctl->dst_tty_path, "w", stdout)) == NULL)
err(EXIT_FAILURE, "%s", ctl->dst_tty_path);
sigact.sa_handler = signal_handler;
sigemptyset(&sigact.sa_mask);
@ -277,10 +279,10 @@ static void do_write(const struct write_control *ctl)
printf("\r\n\a\a\a");
if (strcmp(login, pwuid))
printf(_("Message from %s@%s (as %s) on %s at %s ..."),
login, host, pwuid, ctl->src_tty, timestamp);
login, host, pwuid, ctl->src_tty_name, timestamp);
else
printf(_("Message from %s@%s on %s at %s ..."),
login, host, ctl->src_tty, timestamp);
login, host, ctl->src_tty_name, timestamp);
free(host);
printf("\r\n");
@ -329,25 +331,16 @@ int main(int argc, char **argv)
else
src_fd = -1;
if (src_fd != -1) {
if (!(ctl.src_tty = ttyname(src_fd)))
errx(EXIT_FAILURE,
_("can't find your tty's name"));
/*
* We may have /dev/ttyN but also /dev/pts/xx. Below,
* check_tty() will put "/dev/" in front, so remove that
* part.
*/
if (!strncmp(ctl.src_tty, "/dev/", 5))
ctl.src_tty += 5;
if (check_tty(ctl.src_tty, &tty_writeable, NULL, 1))
if (src_fd != -1 &&
get_terminal_name(src_fd, &ctl.src_tty_path, &ctl.src_tty_name, NULL) == 0) {
if (check_tty(ctl.src_tty_path, &tty_writeable, NULL, 1))
exit(EXIT_FAILURE);
if (!tty_writeable)
errx(EXIT_FAILURE,
_("you have write permission turned off"));
tty_writeable = 0;
} else
ctl.src_tty = "<no tty>";
ctl.src_tty_name = "<no tty>";
ctl.src_uid = getuid();
@ -361,23 +354,25 @@ int main(int argc, char **argv)
case 3:
ctl.dst_login = argv[1];
if (!strncmp(argv[2], "/dev/", 5))
xstrncpy(ctl.dst_tty, argv[2] + 5, sizeof(ctl.dst_tty));
ctl.dst_tty_path = xstrdup(argv[2]);
else
xstrncpy(ctl.dst_tty, argv[2], sizeof(ctl.dst_tty));
xasprintf(&ctl.dst_tty_path, "/dev/%s", argv[2]);
ctl.dst_tty_name = ctl.dst_tty_path + 5;
if (check_utmp(&ctl))
errx(EXIT_FAILURE,
_("%s is not logged in on %s"),
ctl.dst_login, ctl.dst_tty);
if (check_tty(ctl.dst_tty, &tty_writeable, NULL, 1))
ctl.dst_login, ctl.dst_tty_name);
if (check_tty(ctl.dst_tty_path, &tty_writeable, NULL, 1))
exit(EXIT_FAILURE);
if (ctl.src_uid && !tty_writeable)
errx(EXIT_FAILURE,
_("%s has messages disabled on %s"),
ctl.dst_login, ctl.dst_tty);
ctl.dst_login, ctl.dst_tty_name);
do_write(&ctl);
break;
default:
usage(stderr);
}
free(ctl.dst_tty_path);
return EXIT_SUCCESS;
}