From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 1792) id 540743858C62; Thu, 15 Sep 2022 19:55:31 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 540743858C62 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sourceware.org; s=default; t=1663271731; bh=tLMaJ6blTgeV4if13Epomm7nX/WIGBQHD9FcTLLC7L8=; h=From:To:Subject:Date:From; b=tlTke31T58+fmVvk7ppRrYCn18vDlFPvGLCpEhP161wsSTv+KOQ2wI1cY43zcT1+h hBbQ5CS/BTsZKc8moleoAKl0jYtBtqvGbPk3WuoK/eJwPiyTksRPKPd9ucPqLMKxwP kudIjcRpd4s0h6/iRgg+Anwm7+vQvTQmuKgGixpE= Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit From: Samuel Thibault To: glibc-cvs@sourceware.org Subject: [glibc] hurd: Make readlink* just reopen the file used for stat X-Act-Checkin: glibc X-Git-Author: Samuel Thibault X-Git-Refname: refs/heads/master X-Git-Oldrev: 9e5c991106cb04b489272de0ef6a7a6bcef50477 X-Git-Newrev: 5652e12cce80825297c3e0666991deb10310343c Message-Id: <20220915195531.540743858C62@sourceware.org> Date: Thu, 15 Sep 2022 19:55:31 +0000 (GMT) List-Id: https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=5652e12cce80825297c3e0666991deb10310343c commit 5652e12cce80825297c3e0666991deb10310343c Author: Samuel Thibault Date: Thu Sep 15 21:53:57 2022 +0200 hurd: Make readlink* just reopen the file used for stat 9e5c991106cb ("hurd: Fix readlink() hanging on fifo") separated opening the file for the stat call from opening the file for the read call. That however opened a small window for the file to change. Better make this atomic by reopening the file with O_READ. Diff: --- sysdeps/mach/hurd/readlink.c | 32 ++++++++++++++++++++------------ sysdeps/mach/hurd/readlinkat.c | 32 ++++++++++++++++++++------------ 2 files changed, 40 insertions(+), 24 deletions(-) diff --git a/sysdeps/mach/hurd/readlink.c b/sysdeps/mach/hurd/readlink.c index 2d75ef7725..34f132cb92 100644 --- a/sysdeps/mach/hurd/readlink.c +++ b/sysdeps/mach/hurd/readlink.c @@ -28,33 +28,41 @@ ssize_t __readlink (const char *file_name, char *buf, size_t len) { error_t err; - file_t file; + file_t file_stat; struct stat64 st; - file = __file_name_lookup (file_name, O_NOLINK, 0); - if (file == MACH_PORT_NULL) + file_stat = __file_name_lookup (file_name, O_NOLINK, 0); + if (file_stat == MACH_PORT_NULL) return -1; - err = __io_stat (file, &st); + err = __io_stat (file_stat, &st); if (! err) if (S_ISLNK (st.st_mode)) { + enum retry_type doretry; + char retryname[1024]; + file_t file; char *rbuf = buf; - __mach_port_deallocate (__mach_task_self (), file); - file = __file_name_lookup (file_name, O_READ | O_NOLINK, 0); - - err = __io_read (file, &rbuf, &len, 0, len); - if (!err && rbuf != buf) + err = __dir_lookup (file_stat, "", O_READ | O_NOLINK, 0, &doretry, retryname, &file); + if (! err && (doretry != FS_RETRY_NORMAL || retryname[0] != '\0')) + err = EGRATUITOUS; + if (! err) { - memcpy (buf, rbuf, len); - __vm_deallocate (__mach_task_self (), (vm_address_t)rbuf, len); + err = __io_read (file, &rbuf, &len, 0, len); + if (!err && rbuf != buf) + { + memcpy (buf, rbuf, len); + __vm_deallocate (__mach_task_self (), (vm_address_t)rbuf, len); + } + + __mach_port_deallocate (__mach_task_self (), file); } } else err = EINVAL; - __mach_port_deallocate (__mach_task_self (), file); + __mach_port_deallocate (__mach_task_self (), file_stat); if (err) return __hurd_fail (err); diff --git a/sysdeps/mach/hurd/readlinkat.c b/sysdeps/mach/hurd/readlinkat.c index 113b92b732..278a0b5b00 100644 --- a/sysdeps/mach/hurd/readlinkat.c +++ b/sysdeps/mach/hurd/readlinkat.c @@ -29,33 +29,41 @@ ssize_t readlinkat (int fd, const char *file_name, char *buf, size_t len) { error_t err; - file_t file; + file_t file_stat; struct stat64 st; - file = __file_name_lookup_at (fd, 0, file_name, O_NOLINK, 0); - if (file == MACH_PORT_NULL) + file_stat = __file_name_lookup_at (fd, 0, file_name, O_NOLINK, 0); + if (file_stat == MACH_PORT_NULL) return -1; - err = __io_stat (file, &st); + err = __io_stat (file_stat, &st); if (! err) if (S_ISLNK (st.st_mode)) { + enum retry_type doretry; + char retryname[1024]; + file_t file; char *rbuf = buf; - __mach_port_deallocate (__mach_task_self (), file); - file = __file_name_lookup_at (fd, 0, file_name, O_READ | O_NOLINK, 0); - - err = __io_read (file, &rbuf, &len, 0, len); - if (!err && rbuf != buf) + err = __dir_lookup (file_stat, "", O_READ | O_NOLINK, 0, &doretry, retryname, &file); + if (! err && (doretry != FS_RETRY_NORMAL || retryname[0] != '\0')) + err = EGRATUITOUS; + if (! err) { - memcpy (buf, rbuf, len); - __vm_deallocate (__mach_task_self (), (vm_address_t)rbuf, len); + err = __io_read (file, &rbuf, &len, 0, len); + if (!err && rbuf != buf) + { + memcpy (buf, rbuf, len); + __vm_deallocate (__mach_task_self (), (vm_address_t)rbuf, len); + } + + __mach_port_deallocate (__mach_task_self (), file); } } else err = EINVAL; - __mach_port_deallocate (__mach_task_self (), file); + __mach_port_deallocate (__mach_task_self (), file_stat); return err ? __hurd_fail (err) : len; }