From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on dcvr.yhbt.net X-Spam-Level: X-Spam-ASN: AS31976 209.132.180.0/23 X-Spam-Status: No, score=-3.9 required=3.0 tests=AWL,BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_EF,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,RCVD_IN_DNSWL_MED,SPF_HELO_PASS,SPF_PASS shortcircuit=no autolearn=ham autolearn_force=no version=3.4.2 Received: from sourceware.org (server1.sourceware.org [209.132.180.131]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dcvr.yhbt.net (Postfix) with ESMTPS id EB4C61F4B5 for ; Tue, 12 Nov 2019 11:50:18 +0000 (UTC) DomainKey-Signature: a=rsa-sha1; c=nofws; d=sourceware.org; h=list-id :list-unsubscribe:list-subscribe:list-archive:list-post :list-help:sender:date:from:to:cc:message-id:subject:references :reply-to:mime-version:content-transfer-encoding:content-type; q=dns; s=default; b=ulg22n4ACOwQz3s5QMUp9PWwlLnlMGBgIRuk9iLYxim ONAD5d0YPH4L+UWFWh4LFv4bepRcHtBC1tGsdGE30S2+unhaFPlMj1ZnEMB5LA28 ZZy1Wu6zVhTHQBq1ppCBlWBaHuXoQUPaBW+Eupn2teYuOkD9w0AV9kYXGt6Ur1PU = DKIM-Signature: v=1; a=rsa-sha1; c=relaxed; d=sourceware.org; h=list-id :list-unsubscribe:list-subscribe:list-archive:list-post :list-help:sender:date:from:to:cc:message-id:subject:references :reply-to:mime-version:content-transfer-encoding:content-type; s=default; bh=KeXJwTXr0Sgc1sMsSJtiT/MBEJ4=; b=FNao7sMpx/ol4Nkwp nJBCQHePZaI2FmTXvimdOyw3JWulKWH0v2NxIyNTnWw0xaX6numzaEdDA3obvknl c7W0jKwUsg7hZmHmSs8p7lDpSgH4taUpkA7cFmJD1IEmcSIKyA8bWkJrM7VwWePJ MS87TSIJPREU8X3Gq6LFfdi6u0= Received: (qmail 107270 invoked by alias); 12 Nov 2019 11:50:16 -0000 Mailing-List: contact libc-alpha-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Unsubscribe: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: libc-alpha-owner@sourceware.org Received: (qmail 107257 invoked by uid 89); 12 Nov 2019 11:50:16 -0000 Authentication-Results: sourceware.org; auth=none X-HELO: mx1.osci.io X-Gerrit-PatchSet: 1 Date: Tue, 12 Nov 2019 06:50:10 -0500 From: "Florian Weimer (Code Review)" To: libc-alpha@sourceware.org Cc: Florian Weimer Message-ID: Auto-Submitted: auto-generated X-Gerrit-MessageType: newchange Subject: [review] login: Introduce matches_last_entry to utmp processing X-Gerrit-Change-Id: Ib8a85002f7f87ee41590846d16d7e52bdb82f5a5 X-Gerrit-Change-Number: 614 X-Gerrit-ChangeURL: X-Gerrit-Commit: c5f45a31360d3dc31b9f79f93579ca13c87dfe1e References: Reply-To: fweimer@redhat.com, fweimer@redhat.com, libc-alpha@sourceware.org MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Disposition: inline User-Agent: Gerrit/3.0.3-76-gf8b6da0ab5 Content-Type: text/plain; charset=UTF-8 Change URL: https://gnutoolchain-gerrit.osci.io/r/c/glibc/+/614 ...................................................................... login: Introduce matches_last_entry to utmp processing This simplifies internal_getut_nolock and fixes a regression, introduced in commit be6b16d975683e6cca57852cd4cfe715b2a9d8b1 ("login: Acquire write lock early in pututline [BZ #24882]") in pututxline because __utmp_equal can only compare process-related utmp entries. Fixes: be6b16d975683e6cca57852cd4cfe715b2a9d8b1 Change-Id: Ib8a85002f7f87ee41590846d16d7e52bdb82f5a5 --- M login/utmp_file.c 1 file changed, 31 insertions(+), 49 deletions(-) diff --git a/login/utmp_file.c b/login/utmp_file.c index 917c4c5..c41d17b 100644 --- a/login/utmp_file.c +++ b/login/utmp_file.c @@ -43,6 +43,25 @@ /* Cache for the last read entry. */ static struct utmp last_entry; +/* Returns true if *ENTRY matches last_entry, based on + data->ut_type. */ +static bool +matches_last_entry (const struct utmp *data) +{ + if (file_offset <= 0) + /* Nothing has been read. last_entry is stale and cannot match. */ + return false; + + if (data->ut_type == RUN_LVL + || data->ut_type == BOOT_TIME + || data->ut_type == OLD_TIME + || data->ut_type == NEW_TIME) + /* For some entry types, only a type match is required. */ + return data->ut_type == last_entry.ut_type; + else + /* For the process-related entries, a full match is needed. */ + return __utmp_equal (&last_entry, data); +} /* Locking timeout. */ #ifndef TIMEOUT @@ -133,9 +152,6 @@ __lseek64 (file_fd, 0, SEEK_SET); file_offset = 0; - /* Make sure the entry won't match. */ - last_entry.ut_type = -1; - return 1; } @@ -191,48 +207,20 @@ static int internal_getut_nolock (const struct utmp *id) { - if (id->ut_type == RUN_LVL || id->ut_type == BOOT_TIME - || id->ut_type == OLD_TIME || id->ut_type == NEW_TIME) + while (1) { - /* Search for next entry with type RUN_LVL, BOOT_TIME, - OLD_TIME, or NEW_TIME. */ - - while (1) + /* Read the next entry. */ + if (__read_nocancel (file_fd, &last_entry, sizeof (struct utmp)) + != sizeof (struct utmp)) { - /* Read the next entry. */ - if (__read_nocancel (file_fd, &last_entry, sizeof (struct utmp)) - != sizeof (struct utmp)) - { - __set_errno (ESRCH); - file_offset = -1l; - return -1; - } - file_offset += sizeof (struct utmp); - - if (id->ut_type == last_entry.ut_type) - break; + __set_errno (ESRCH); + file_offset = -1l; + return -1; } - } - else - { - /* Search for the next entry with the specified ID and with type - INIT_PROCESS, LOGIN_PROCESS, USER_PROCESS, or DEAD_PROCESS. */ + file_offset += sizeof (struct utmp); - while (1) - { - /* Read the next entry. */ - if (__read_nocancel (file_fd, &last_entry, sizeof (struct utmp)) - != sizeof (struct utmp)) - { - __set_errno (ESRCH); - file_offset = -1l; - return -1; - } - file_offset += sizeof (struct utmp); - - if (__utmp_equal (&last_entry, id)) - break; - } + if (matches_last_entry (id)) + break; } return 0; @@ -365,13 +353,7 @@ /* Find the correct place to insert the data. */ bool found = false; - if (file_offset > 0 - && ((last_entry.ut_type == data->ut_type - && (last_entry.ut_type == RUN_LVL - || last_entry.ut_type == BOOT_TIME - || last_entry.ut_type == OLD_TIME - || last_entry.ut_type == NEW_TIME)) - || __utmp_equal (&last_entry, data))) + if (matches_last_entry (data)) { if (__lseek64 (file_fd, file_offset, SEEK_SET) < 0) { @@ -389,7 +371,7 @@ found = false; } else - found = __utmp_equal (&last_entry, data); + found = matches_last_entry (data); } if (!found) -- Gerrit-Project: glibc Gerrit-Branch: master Gerrit-Change-Id: Ib8a85002f7f87ee41590846d16d7e52bdb82f5a5 Gerrit-Change-Number: 614 Gerrit-PatchSet: 1 Gerrit-Owner: Florian Weimer Gerrit-MessageType: newchange