Path: csiph.com!xmission!news.snarked.org!news.linkpendium.com!news.linkpendium.com!panix!usenet.stanford.edu!not-for-mail From: Chet Ramey Newsgroups: gnu.bash.bug Subject: Re: process substitution fd lifetime race condition Date: Mon, 20 Apr 2020 18:08:30 -0400 Organization: ITS, Case Western Reserve University Lines: 16 Approved: bug-bash@gnu.org Message-ID: References: <20200420051508.GA2359844@zx2c4.com> <7496b183-2db3-6c03-6074-928adcd08f45@case.edu> <01e85de9-95ef-20fd-7221-a54a0a2a304a@case.edu> <0fd24573-e788-a8eb-8050-14c603a3817f@case.edu> Reply-To: chet.ramey@case.edu NNTP-Posting-Host: lists.gnu.org Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit X-Trace: usenet.stanford.edu 1587420523 18600 209.51.188.17 (20 Apr 2020 22:08:43 GMT) X-Complaints-To: action@cs.stanford.edu Cc: chet.ramey@case.edu, bug-bash@gnu.org To: "Jason A. Donenfeld" Envelope-to: bug-bash@gnu.org DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=case.edu; s=smtp-primary; t=1587420515; bh=Knp422WOfNY/K9wAPLbC5ssaYK/1IYdDIaJVRFxuhQs=; h=Reply-To:Cc:Subject:To:References:From:Message-ID:Date: MIME-Version:In-Reply-To:Content-Type:Content-Transfer-Encoding; b=XCCTNK4mBMF+Giw4/fwc21yAcfjkJNtNTGZbX2wYEfSxGK+LF3LmE/CR0n+MzXzftn upGWDWgQjToCB2pdaoQxtEe5RScAwsq6JMNVSomPn0hV/QkfZLEOb+HfUuKKM2hWRJe 5l1bhX3YEIqhCnMydgqtochZbgngdD2/LlB0V5Qef/yMu3+A+1dL+Ns5/GRwqSKtuYY I0+qD6+myXtJYFykSq2SKzxFLY2vYXehEkpG6ydW2cxfLHPcSrhvTepToSJpso1w7R7 3FcrYkF05Xa4OwnBL9acFLaTN3H8H3DwFIIIZIWXOlgxODh5hkCoWpRI+AsXsyL7ZVn Y3Ju2i+w== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=case.edu; s=smtp-primary; t=1587420514; bh=nELroWsLgxGv+dQTbDUx5vRUx/srWSucCSg1IyLmCos=; h=Reply-To:Cc:Subject:To:References:From:Message-ID:Date: MIME-Version:In-Reply-To:Content-Type:Content-Transfer-Encoding; b=1u8K1k9WX3/bPXNi/ueRdtliknnTlSHSjIkqFhokoxs4/0b2iuYqaJd6AsZEhcM7q5 13mZZFhLkI6Z6J3zoZPM+ow4+XsiJ8kvczlYphdhJCDloJ8BiLbQQ3ladGkcvVhlWZ6 7hlp/3Wm286usB5zcC5OznT0M4iOXtra/J9usaXV5qp1VZSaPYVND3jfJpF3cmKdbRf MnTUM0/Sko1lc0dZuTbDpVdzW4jhDnrCv4VoJYIqruq9/YGBClAZgtMsNNR3vgpL1jP aTebIbg2hFWn6Spft6QCR51RB+ge59cpn1TO9PBr3wgVVxbHzB8ES2lLaZwF9v+ROUG qKsAbvfA== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=case.edu; s=g-case; h=reply-to:cc:subject:to:references:from:autocrypt:organization :message-id:date:user-agent:mime-version:in-reply-to :content-language:content-transfer-encoding; bh=nELroWsLgxGv+dQTbDUx5vRUx/srWSucCSg1IyLmCos=; b=SG4HyVbQZjg4lXgG7S9JJs59zoBqV9HiNr5b1nK2SoPQ3pf+6oh5sxBY1H5yMH10qi WC4gwYOTJsMuTG4vgdFszl4GBhr2dGaazYQq92t4DotCfnsRuaJ6L0BIXwjPEuWPCDDJ l3DeP8f/xq95KSID1957Ad2o2ucKjWL78gjaUkLZXjFUcBH9k6TR/dipJhYpTxvIKr91 ytEPLOrq6qluX5o8oQxaVYzSpYCiGqkoi5iW+ecbnGkjXFVJtKHvpqfaAYyvvPSm9ye/ jBsQtgGyfhyzI+IOCoYNzmrMNdzCImqKs42kswoX2BN77bY96FGSZHVcWkjJkT/kwduQ oUVQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:reply-to:cc:subject:to:references:from:autocrypt :organization:message-id:date:user-agent:mime-version:in-reply-to :content-language:content-transfer-encoding; bh=nELroWsLgxGv+dQTbDUx5vRUx/srWSucCSg1IyLmCos=; b=K3k8esQ846PYRPpY2kSj4Z2gxpGtDJcyq5CJ6Ujfdhvd6KVwpQMS6ICK9y3YXZiG2R Gcc4hNq2Ws4yJ8N/ik1hu2d2B59cqs7uj1WArXAKbA7Z3+ptTZoPSe5o7DPnmmZfRiCD 301o+OPaab9uEBFO0m95dJ42xFndOPcEpGJv3Obe7tyjaebZqymLl+8HmmNHVczvN/av R7P5N+Q/16NeKh7jrnyMlP9Yyxsp/67PgJ1EXZOujA4b0uNs+rhCFL10KJTfQp5K9HYk Uetp4TjWchcv4y0dnfSb8M0yerl5ZGL2IvifXbMUSQ5hha8l5MbK1bxKTzJwme4GCexT 1FHg== X-Gm-Message-State: AGi0PuZ+k0rvU9Cip8Q2Y3sK6upzhkEmGDqAqbSSakCs6NJVGPopaLSs iM1oMwKA+o4GrUab+THOJ4nBaTlntAezGU+3TYko0Q8vXRMckeZOsH2FTow4EPasMq8nmtlQ9S4 2se5H+XTS59E= X-Received: by 2002:a0c:eb0e:: with SMTP id j14mr16377642qvp.230.1587420513296; Mon, 20 Apr 2020 15:08:33 -0700 (PDT) X-Google-Smtp-Source: APiQypLk3If2dGwCP316Fe64UB44oWvsxba7YphGtPolNPlkS1FgwRK58Udg3HhODePjgEyuFYaOyw== X-Received: by 2002:a0c:eb0e:: with SMTP id j14mr16377610qvp.230.1587420512914; Mon, 20 Apr 2020 15:08:32 -0700 (PDT) Autocrypt: addr=chet.ramey@case.edu; prefer-encrypt=mutual; keydata= mQGiBEEOsGwRBACFa0A1oa71HSZLWxAx0svXzhOZNQZOzqHmSuGOG92jIpQpr8DpvgRh40Yp AwdcXb8QG1J5yGAKeevNE1zCFaA725vGSdHUyypHouV0xoWwukYO6qlyyX+2BZU+okBUqoWQ koWxiYaCSfzB2Ln7pmdys1fJhcgBKf3VjWCjd2XJTwCgoFJOwyBFJdugjfwjSoRSwDOIMf0D /iQKqlWhIO1LGpMrGX0il0/x4zj0NAcSwAk7LaPZbN4UPjn5pqGEHBlf1+xDDQCkAoZ/VqES GZragl4VqJfxBr29Ag0UDvNbUbXoxQsARdero1M8GiAIRc50hj7HXFoERwenbNDJL86GPLAQ OTGOCa4W2o29nFfFjQrsrrYHzVtyA/9oyKvTeEMJ7NA3VJdWcmn7gOu0FxEmSNhSoV1T4vP2 1Wf7f5niCCRKQLNyUy0wEApQi4tSysdz+AbgAc0b/bHYVzIf2uO2lIEZQNNt+3g2bmXgloWm W5fsm/di50Gm1l1Na63d3RZ00SeFQos6WEwLUHEB0yp6KXluXLLIZitEJLQwQ2hldCBSYW1l eSAoQ2FzZSBzdGFuZGFyZCkgPGNoZXQucmFtZXlAY2FzZS5lZHU+iF8EExECAB8FAkPi19EC GwMHCwkIBwMCAQMVAgMDFgIBAh4BAheAAAoJELtYafBk6nSrelkAn31Gsuib7GcCZHbv5L5t VKYR9LklAJ4hzUHKA49Z0QXR+qCb80osIcmPSbkBDQRBDrBvEAQAkK6TAOKBEM+EC4j6V/7o /riVZqcgU5cid2qG9TXdwNtD9a3kvA/ObZBO93sX59wc6Bnwo4VJxsOmMlpGrAjJsxNwg3QH akEtf8LXRbVpj5xStdmBdQZUhIQyalo/2/TZq5OijtddUQcL5cs70hTv/FpT3wUvr2Xr8rjF 41IFEz8AAwcD/A0CZEGlzIrT5WCBnl6xBog/8vKiUCbarByat3d1mL6DbizvKNXQRTC9E/vE dENAWCQCjr75Bu55xT8n3SXGtWdDC5xmZ/P3OBYORP8yl8H8I1FIosWOFirbIeYdZPq8SPD1 HL+EXo9zSiHVrrZRJ19ooCKKbSdXHFCY+aJG+0KZiEkEGBECAAkFAkEOsG8CGwwACgkQu1hp 8GTqdKvjcACfZlkVCDwaz/NTO9cy3t69oWpVPNwAnRwe0qk/WL/gfhH346xh5B3HFbFN User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.14; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 In-Reply-To: Content-Language: en-US X-Mirapoint-IP-Reputation: reputation=Good-1, source=Queried, refid=tid=0001.0A020301.5E9E180E.00C3, actions=tag X-Mirapoint-IP-Reputation: reputation=good-1, source=Fixed, refid=n/a, actions=tag X-Junkmail-Status: score=8/80, host=mpv4-2015.case.edu X-Junkmail-PrAS-Raw: score=8/80, refid=2.7.2:2020.4.20.212117:17:8.317, ip=, rules=__YOUTUBE_RCVD, DKIM_SIGNATURE, __X_GOOGLE_DKIM_SIGNATURE, __HAS_REPLYTO, __HAS_CC_HDR, __MULTIPLE_RCPTS_CC_X2, __SUBJ_REPLY, __BOUNCE_CHALLENGE_SUBJ, __BOUNCE_NDR_SUBJ_EXEMPT, __SUBJ_ALPHA_END, __TO_MALFORMED_2, __TO_NAME, __TO_NAME_DIFF_FROM_ACC, __HAS_REFERENCES, __REFERENCES, __HAS_FROM, FROM_EDU_TLD, __HAS_MSGID, __SANE_MSGID, DATE_TZ_NA, __USER_AGENT, __MOZILLA_USER_AGENT, __MIME_VERSION, __IN_REP_TO, __CT, __CT_TEXT_PLAIN, __CTE, __REPLYTO_SAMEAS_FROM_ADDY, __REPLYTO_SAMEAS_FROM_ACC, __FROM_DOMAIN_IN_ANY_CC2, __REPLYTO_SAMEAS_FROM_DOMAIN, __DKIM_ALIGNS_1, __DKIM_ALIGNS_2, __ANY_URI, __URI_MAILTO, __URI_WITH_PATH, __URI_ENDS_IN_SLASH, __URI_NO_WWW, __CP_URI_IN_BODY, __SUBJ_ALPHA_NEGATE, __COURIER_PHRASE, __URI_IN_BODY, __URI_NOT_IMG, __MAIL_CHAIN, __FORWARDED_MSG, __BODY_NO_MAILTO, __NO_HTML_TAG_RAW, BODY_SIZE_600_699, BODYTEXTP_SIZE_3000_LESS, [TRUNCATED], so=2010-03-03 19:42:08, dmn=2016-08-03-0138 Received-SPF: pass client-ip=129.22.103.195; envelope-from=chet.ramey@case.edu; helo=mpv4-2015.case.edu X-detected-operating-system: by eggs.gnu.org: First seen = 2020/04/20 15:50:25 X-ACL-Warn: Detected OS = Linux 2.4.x-2.6.x [generic] [fuzzy] X-Received-From: 129.22.103.195 X-BeenThere: bug-bash@gnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Bug reports for the GNU Bourne Again SHell List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-Mailman-Original-Message-ID: <0fd24573-e788-a8eb-8050-14c603a3817f@case.edu> X-Mailman-Original-References: <20200420051508.GA2359844@zx2c4.com> <7496b183-2db3-6c03-6074-928adcd08f45@case.edu> <01e85de9-95ef-20fd-7221-a54a0a2a304a@case.edu> Xref: csiph.com gnu.bash.bug:16210 On 4/20/20 6:02 PM, Jason A. Donenfeld wrote: > It seems like process substitution fifo lifetime is really tricky. You > can't really reference track, since the path is just a string that > could be manipulated. So how do you know when it's safe to clean up > that fd and that nobody is using it? In general, you clean up a procsub fd, and remove any named pipes from the file system, when the block that uses it (or created it) ends. That is, as you noticed, sometimes tricky. -- ``The lyf so short, the craft so long to lerne.'' - Chaucer ``Ars longa, vita brevis'' - Hippocrates Chet Ramey, UTech, CWRU chet@case.edu http://tiswww.cwru.edu/~chet/