glibc documentation tells getutent() calls are not thread safe, and recommends to copy the context of the structures when information is wished to be stored. This leads to excessive copying, that in this case is not relevant. write(1) is single threaded program and there is no reason to assume this would change in future. Reference: http://www.gnu.org/software/libc/manual/html_node/Manipulating-the-Database.html Signed-off-by: Sami Kerola <kerolasa@xxxxxx> --- term-utils/write.c | 28 +++++++++++----------------- 1 file changed, 11 insertions(+), 17 deletions(-) diff --git a/term-utils/write.c b/term-utils/write.c index 6bf15dd..8288e9d 100644 --- a/term-utils/write.c +++ b/term-utils/write.c @@ -126,17 +126,15 @@ static int check_tty(char *tty, int *tty_writeable, time_t *tty_atime, int showe */ static int check_utmp(const struct write_control *ctl) { - struct utmp u; - struct utmp *uptr; + struct utmp *u; int res = 1; utmpname(_PATH_UTMP); setutent(); - while ((uptr = getutent())) { - memcpy(&u, uptr, sizeof(u)); - 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) { + 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) { res = 0; break; } @@ -159,38 +157,34 @@ static int check_utmp(const struct write_control *ctl) */ static void search_utmp(struct write_control *ctl) { - struct utmp u; - struct utmp *uptr; + 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 atty[sizeof(u.ut_line) + 1]; utmpname(_PATH_UTMP); setutent(); - while ((uptr = getutent())) { - memcpy(&u, uptr, sizeof(u)); - if (strncmp(ctl->dst_login, u.ut_user, sizeof(u.ut_user)) == 0) { + while ((u = getutent())) { + if (strncmp(ctl->dst_login, u->ut_user, sizeof(u->ut_user)) == 0) { num_ttys++; - xstrncpy(atty, u.ut_line, sizeof(atty)); - if (check_tty(atty, &tty_writeable, &tty_atime, 0)) + if (check_tty(u->ut_line, &tty_writeable, &tty_atime, 0)) /* bad term? skip */ continue; if (ctl->src_uid && !tty_writeable) /* skip ttys with msgs off */ continue; - if (strcmp(atty, ctl->src_tty) == 0) { + if (strcmp(u->ut_line, ctl->src_tty) == 0) { user_is_me = 1; /* don't write to yourself */ continue; } - if (u.ut_type != USER_PROCESS) + if (u->ut_type != USER_PROCESS) /* it's not a valid entry */ continue; valid_ttys++; if (tty_atime > best_atime) { best_atime = tty_atime; - xstrncpy(ctl->dst_tty, atty, sizeof(ctl->dst_tty)); + xstrncpy(ctl->dst_tty, u->ut_line, sizeof(ctl->dst_tty)); } } } -- 2.9.0 -- 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
