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Wed, 04 Oct 2023 03:29:23 -0700 (PDT) MIME-Version: 1.0 From: Chris McGee Date: Wed, 4 Oct 2023 06:29:12 -0400 Message-ID: To: Fans of the OS Plan 9 from Bell Labs <9fans@9fans.net> Content-Type: multipart/alternative; boundary=0000000000001c3a430606e17b96 Topicbox-Policy-Reasoning: allow: sender is a member Topicbox-Message-UUID: e6f602fa-62a0-11ee-af71-ff77abbcfca5 Archived-At: =?UTF-8?B?PGh0dHBzOi8vOWZhbnMudG9waWNib3guY29tL2dyb3Vwcy85?= =?UTF-8?B?ZmFucy9UZmFhMjU1NGE5Yjc0YzQ3OS1NNmI1MThjYWI5MDFkY2Y2YmY2MGJk?= =?UTF-8?B?MjgwPg==?= List-Help: List-Id: "9fans" <9fans.9fans.net> List-Post: List-Software: Topicbox v0 List-Subscribe: Precedence: list Reply-To: 9fans <9fans@9fans.net> Subject: [9fans] fd and /srv filesystem Content-Transfer-Encoding: 7bit List-Unsubscribe: , Topicbox-Delivery-ID: 2:9fans:437d30aa-c441-11e9-8a57-d036212d11b0:522be890-2105-11eb-b15e-8d699134e1fa:M6b518cab901dcf6bf60bd280:1:YhfvVpje9mfC9OMCpFPA-GApdNaW9OBUBQ2YznCkSd8 --0000000000001c3a430606e17b96 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Hi All, I was thinking about file descriptors in the context of Plan 9. On Unix an fd is generally only usable by the current process, and child ones through a fork with some special incantation if one wants to communicate one over a domain socket. This is possibly for security reasons, avoiding other users' processes from trying to guess the fd of a critical file. It's common practice in Plan 9 to post an fd (sometimes via a pipe) from one process to the /srv filesystem so that others can discover it and open a comms channel. Does the kernel transform the fd into something when posted to /srv so that it can be consumed by any other process in the system? Thanks, Chris ------------------------------------------ 9fans: 9fans Permalink: https://9fans.topicbox.com/groups/9fans/Tfaa2554a9b74c479-M6b518= cab901dcf6bf60bd280 Delivery options: https://9fans.topicbox.com/groups/9fans/subscription --0000000000001c3a430606e17b96 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
Hi All,

I was = thinking about file descriptors in the context of Plan 9. On Unix an fd is = generally only usable by the current process, and child ones through a fork= with some special incantation if one wants to communicate one over a domai= n socket. This is possibly for security reasons, avoiding other users' = processes from trying to guess the fd of a critical file.

<= /div>
It's common practice in Plan 9 to post an fd (sometimes via a= pipe) from one process to the /srv filesystem so that others can discover = it and open a comms channel. Does the kernel transform the fd into somethin= g when posted to /srv so that it can be consumed by any other process in th= e system?

Thanks,
Chris
= --0000000000001c3a430606e17b96--