From patchwork Tue May 4 01:51:52 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: =?utf-8?q?=C3=89rico_Nogueira?= X-Patchwork-Id: 43248 Return-Path: X-Original-To: patchwork@sourceware.org Delivered-To: patchwork@sourceware.org Received: from server2.sourceware.org (localhost [IPv6:::1]) by sourceware.org (Postfix) with ESMTP id CE601395040D; Tue, 4 May 2021 01:52:19 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org CE601395040D DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sourceware.org; s=default; t=1620093139; bh=hAZijA1luVOibF6Tbt+eEZ512yNUO/EmIqlewc2ef2o=; h=To:Subject:Date:In-Reply-To:References:List-Id:List-Unsubscribe: List-Archive:List-Post:List-Help:List-Subscribe:From:Reply-To:Cc: From; b=gmPDx6E4TVtdc2r2dtppx7Xh3TlN06ZMOku+d1z57sLGyj6FNVlNNDTIB0Qy/tNHd IaE7VjdVP+u6ewp37iiX7Uj8iSphPpK9m3R9Ep1THZGz+eTUJZ9cCmdvP8R+T4lfxe pQ4nSYtmr0N/xn8oNgp40LjeaFpyl5MYyJ5CSxDA= X-Original-To: libc-alpha@sourceware.org Delivered-To: libc-alpha@sourceware.org Received: from knopi.disroot.org (knopi.disroot.org [178.21.23.139]) by sourceware.org (Postfix) with ESMTPS id 76EFA3945C29 for ; Tue, 4 May 2021 01:52:15 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.3.2 sourceware.org 76EFA3945C29 Received: from localhost (localhost [127.0.0.1]) by disroot.org (Postfix) with ESMTP id EF56653AE8; Tue, 4 May 2021 03:52:13 +0200 (CEST) X-Virus-Scanned: Debian amavisd-new at disroot.org Received: from knopi.disroot.org ([127.0.0.1]) by localhost (disroot.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 7g4L7kRm_8hj; Tue, 4 May 2021 03:52:12 +0200 (CEST) To: libc-alpha@sourceware.org Subject: [PATCH 3/3] linux: implement ttyname as a wrapper around ttyname_r. Date: Mon, 3 May 2021 22:51:52 -0300 Message-Id: <20210504015152.31064-3-ericonr@disroot.org> In-Reply-To: <20210504015152.31064-1-ericonr@disroot.org> References: <20210504015152.31064-1-ericonr@disroot.org> Mime-Version: 1.0 X-Spam-Status: No, score=-13.4 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, GIT_PATCH_0, SPF_HELO_NONE, SPF_PASS, TXREP autolearn=ham autolearn_force=no version=3.4.2 X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on server2.sourceware.org X-BeenThere: libc-alpha@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libc-alpha mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-Patchwork-Original-From: =?utf-8?q?=C3=89rico_Nogueira_via_Libc-alpha?= From: =?utf-8?q?=C3=89rico_Nogueira?= Reply-To: =?utf-8?q?=C3=89rico_Nogueira?= Cc: =?utf-8?q?=C3=89rico_Nogueira?= Errors-To: libc-alpha-bounces@sourceware.org Sender: "Libc-alpha" Big win in binary size and avoids duplicating the logic in multiple places. On x86_64, dropped from 1883206 to 1881790, a 1416 byte decrease. Also changed logic to track if ttyname_buf has been allocated by checking if it's NULL instead of tracking buflen as an additional variable. --- I was going to simply change the function to use __fd_to_filename, like the 2/3 patch, but this felt like a better improvement. However, I haven't studied the implications deeply or verified if the ttyname() logic behaved noticeably (or subtly) different than what ttyname_r() did. sysdeps/unix/sysv/linux/ttyname.c | 161 ++---------------------------- 1 file changed, 9 insertions(+), 152 deletions(-) diff --git a/sysdeps/unix/sysv/linux/ttyname.c b/sysdeps/unix/sysv/linux/ttyname.c index d561ac12f2..a2bb81c78b 100644 --- a/sysdeps/unix/sysv/linux/ttyname.c +++ b/sysdeps/unix/sysv/linux/ttyname.c @@ -17,17 +17,9 @@ #include #include -#include -#include -#include -#include #include -#include -#include #include -#include <_itoa.h> - #include "ttyname.h" #if 0 @@ -35,170 +27,35 @@ char *__ttyname; #endif -static char *getttyname (const char *dev, const struct stat64 *mytty, - int save, int *dostat); - -libc_freeres_ptr (static char *getttyname_name); - -static char * -attribute_compat_text_section -getttyname (const char *dev, const struct stat64 *mytty, int save, int *dostat) -{ - static size_t namelen; - struct stat64 st; - DIR *dirstream; - struct dirent64 *d; - size_t devlen = strlen (dev) + 1; - - dirstream = __opendir (dev); - if (dirstream == NULL) - { - *dostat = -1; - return NULL; - } - - /* Prepare for the loop. If we already have a buffer copy the directory - name we look at into it. */ - if (devlen < namelen) - *((char *) __mempcpy (getttyname_name, dev, devlen - 1)) = '/'; - - while ((d = __readdir64 (dirstream)) != NULL) - if ((d->d_fileno == mytty->st_ino || *dostat) - && strcmp (d->d_name, "stdin") - && strcmp (d->d_name, "stdout") - && strcmp (d->d_name, "stderr")) - { - size_t dlen = _D_ALLOC_NAMLEN (d); - if (devlen + dlen > namelen) - { - free (getttyname_name); - namelen = 2 * (devlen + dlen); /* Big enough. */ - getttyname_name = malloc (namelen); - if (! getttyname_name) - { - *dostat = -1; - /* Perhaps it helps to free the directory stream buffer. */ - (void) __closedir (dirstream); - return NULL; - } - *((char *) __mempcpy (getttyname_name, dev, devlen - 1)) = '/'; - } - memcpy (&getttyname_name[devlen], d->d_name, dlen); - if (__stat64 (getttyname_name, &st) == 0 - && is_mytty (mytty, &st)) - { - (void) __closedir (dirstream); -#if 0 - __ttyname = getttyname_name; -#endif - __set_errno (save); - return getttyname_name; - } - } - - (void) __closedir (dirstream); - __set_errno (save); - return NULL; -} - - +#define TTYNAME_BUFLEN (PATH_MAX-1) /* Static buffer in `ttyname'. */ libc_freeres_ptr (static char *ttyname_buf); - /* Return the pathname of the terminal FD is open on, or NULL on errors. The returned storage is good only until the next call to this function. */ char * ttyname (int fd) { - static size_t buflen; - char procname[30]; - struct stat64 st, st1; - int dostat = 0; - int doispty = 0; - char *name; - int save = errno; - struct termios term; - /* isatty check, tcgetattr is used because it sets the correct - errno (EBADF resp. ENOTTY) on error. */ + errno (EBADF resp. ENOTTY) on error. Fast error path to avoid the allocation */ + struct termios term; if (__glibc_unlikely (__tcgetattr (fd, &term) < 0)) return NULL; - if (__fstat64 (fd, &st) < 0) - return NULL; - - /* We try using the /proc filesystem. */ - *_fitoa_word (fd, __stpcpy (procname, "/proc/self/fd/"), 10, 0) = '\0'; - - if (buflen == 0) + if (ttyname_buf == NULL) { - buflen = 4095; - ttyname_buf = (char *) malloc (buflen + 1); + ttyname_buf = malloc (TTYNAME_BUFLEN + 1); if (ttyname_buf == NULL) { - buflen = 0; return NULL; } } - ssize_t len = __readlink (procname, ttyname_buf, buflen); - if (__glibc_likely (len != -1)) - { - if ((size_t) len >= buflen) - return NULL; - -#define UNREACHABLE_LEN strlen ("(unreachable)") - if (len > UNREACHABLE_LEN - && memcmp (ttyname_buf, "(unreachable)", UNREACHABLE_LEN) == 0) - { - memmove (ttyname_buf, ttyname_buf + UNREACHABLE_LEN, - len - UNREACHABLE_LEN); - len -= UNREACHABLE_LEN; - } - - /* readlink need not terminate the string. */ - ttyname_buf[len] = '\0'; - - /* Verify readlink result, fall back on iterating through devices. */ - if (ttyname_buf[0] == '/' - && __stat64 (ttyname_buf, &st1) == 0 - && is_mytty (&st, &st1)) - return ttyname_buf; - - doispty = 1; - } - - if (__stat64 ("/dev/pts", &st1) == 0 && S_ISDIR (st1.st_mode)) - { - name = getttyname ("/dev/pts", &st, save, &dostat); - } - else - { - __set_errno (save); - name = NULL; - } - - if (!name && dostat != -1) + int result = ttyname_r (fd, ttyname_buf, TTYNAME_BUFLEN); + if (result != 0) { - name = getttyname ("/dev", &st, save, &dostat); - } - - if (!name && dostat != -1) - { - dostat = 1; - name = getttyname ("/dev", &st, save, &dostat); - } - - if (!name && doispty && is_pty (&st)) - { - /* We failed to figure out the TTY's name, but we can at least - signal that we did verify that it really is a PTY slave. - This happens when we have inherited the file descriptor from - a different mount namespace. */ - __set_errno (ENODEV); + __set_errno (result); return NULL; } - - return name; + return ttyname_buf; }