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| author | Sami Kerola | 2015-10-31 19:16:07 +0100 |
|---|---|---|
| committer | Sami Kerola | 2015-11-22 21:56:39 +0100 |
| commit | 010d5a670bc4021d6f1790705fcdde4dcde97b4b (patch) | |
| tree | 512db87df7852590ae8a87b5731fb540aaa9ee0f /term-utils/mesg.c | |
| parent | fdformat: fix block device open race (diff) | |
| download | kernel-qcow2-util-linux-010d5a670bc4021d6f1790705fcdde4dcde97b4b.tar.gz kernel-qcow2-util-linux-010d5a670bc4021d6f1790705fcdde4dcde97b4b.tar.xz kernel-qcow2-util-linux-010d5a670bc4021d6f1790705fcdde4dcde97b4b.zip | |
mesg: fix multiple races
Signed-off-by: Sami Kerola <kerolasa@iki.fi>
Diffstat (limited to 'term-utils/mesg.c')
| -rw-r--r-- | term-utils/mesg.c | 22 |
1 files changed, 14 insertions, 8 deletions
diff --git a/term-utils/mesg.c b/term-utils/mesg.c index 77d89c755..4181a5874 100644 --- a/term-utils/mesg.c +++ b/term-utils/mesg.c @@ -90,7 +90,7 @@ int main(int argc, char *argv[]) { struct stat sb; char *tty; - int ch, verbose = FALSE; + int ch, fd, verbose = FALSE, ret; static const struct option longopts[] = { { "verbose", no_argument, 0, 'v' }, @@ -123,11 +123,13 @@ int main(int argc, char *argv[]) if ((tty = ttyname(STDERR_FILENO)) == NULL) err(MESG_EXIT_FAILURE, _("ttyname failed")); - - if (stat(tty, &sb) < 0) + if ((fd = open(tty, O_RDONLY)) < 0) + err(MESG_EXIT_FAILURE, _("cannot open %s"), tty); + if (fstat(fd, &sb)) err(MESG_EXIT_FAILURE, _("stat of %s failed"), tty); if (!*argv) { + close(fd); if (sb.st_mode & (S_IWGRP | S_IWOTH)) { puts(_("is y")); return IS_ALLOWED; @@ -139,24 +141,28 @@ int main(int argc, char *argv[]) switch (rpmatch(argv[0])) { case RPMATCH_YES: #ifdef USE_TTY_GROUP - if (chmod(tty, sb.st_mode | S_IWGRP) < 0) + if (fchmod(fd, sb.st_mode | S_IWGRP) < 0) #else - if (chmod(tty, sb.st_mode | S_IWGRP | S_IWOTH) < 0) + if (fchmod(fd, sb.st_mode | S_IWGRP | S_IWOTH) < 0) #endif err(MESG_EXIT_FAILURE, _("change %s mode failed"), tty); if (verbose) puts(_("write access to your terminal is allowed")); - return IS_ALLOWED; + ret = IS_ALLOWED; + break; case RPMATCH_NO: - if (chmod(tty, sb.st_mode & ~(S_IWGRP|S_IWOTH)) < 0) + if (fchmod(fd, sb.st_mode & ~(S_IWGRP|S_IWOTH)) < 0) err(MESG_EXIT_FAILURE, _("change %s mode failed"), tty); if (verbose) puts(_("write access to your terminal is denied")); - return IS_NOT_ALLOWED; + ret = IS_NOT_ALLOWED; + break; case RPMATCH_INVALID: warnx(_("invalid argument: %s"), argv[0]); usage(stderr); default: abort(); } + close(fd); + return ret; } |