From owner-freebsd-questions@freebsd.org Fri Mar 20 18:52:28 2020 Return-Path: Delivered-To: freebsd-questions@mailman.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.nyi.freebsd.org (Postfix) with ESMTP id 0B82C26FEC7; Fri, 20 Mar 2020 18:52:28 +0000 (UTC) (envelope-from freebsd@edvax.de) Received: from mout.kundenserver.de (mout.kundenserver.de [212.227.126.130]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) server-signature RSA-PSS (4096 bits) client-signature RSA-PSS (2048 bits) client-digest SHA256) (Client CN "mout.kundenserver.de", Issuer "TeleSec ServerPass Class 2 CA" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 48kXvZ2Ljjz3MMQ; Fri, 20 Mar 2020 18:52:25 +0000 (UTC) (envelope-from freebsd@edvax.de) Received: from r56.edvax.de ([178.12.42.103]) by mrelayeu.kundenserver.de (mreue010 [212.227.15.167]) with ESMTPA (Nemesis) id 1N1fzM-1jQc6Y2tPE-0120d8; Fri, 20 Mar 2020 19:52:22 +0100 Date: Fri, 20 Mar 2020 19:52:22 +0100 From: Polytropon To: Arpan Palit Cc: freebsd-hackers@freebsd.org, freebsd-questions@freebsd.org, freebsd-drivers@freebsd.org Subject: Re: How to access a user space file from kernel space in FreeBSD. 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In general I need to know the > answer for the below questions. > > i). How to open a user space file from driver(kernel space) ? With the open() system call. See "man 2 open" for details. > ii). How to create a new user space file from driver(kernel space) ? With the creat() system call. See "man 2 creat" for details. > iii). How to get file parameters like size of the file ? With the stat() system call. See "man 2 stat" for details. > iv). How to read/write the files from the driver(kernel space) ? With the read() and write() system call. See "man 2 read" and "man 2 write" for details. If you have access to the standard C library (libc) from the driver, you can also use fopen(), fstat(), fread(), fwrite(), fgets(), fputs(), fscanf(), fprintf() et al. for file access. See the corresponding manual pages in section 3. -- Polytropon Magdeburg, Germany Happy FreeBSD user since 4.0 Andra moi ennepe, Mousa, ...