From owner-freebsd-hackers Wed Jun 12 02:58:35 1996 Return-Path: owner-hackers Received: (from root@localhost) by freefall.freebsd.org (8.7.5/8.7.3) id CAA13247 for hackers-outgoing; Wed, 12 Jun 1996 02:58:35 -0700 (PDT) Received: from paris.CS.Berkeley.EDU (paris.CS.Berkeley.EDU [128.32.34.47]) by freefall.freebsd.org (8.7.5/8.7.3) with SMTP id CAA13242 for ; Wed, 12 Jun 1996 02:58:33 -0700 (PDT) Received: from paris.CS.Berkeley.EDU (localhost.Berkeley.EDU [127.0.0.1]) by paris.CS.Berkeley.EDU (8.6.11/8.6.9) with ESMTP id CAA19589 for ; Wed, 12 Jun 1996 02:58:29 -0700 From: Josh MacDonald Message-Id: <199606120958.CAA19589@paris.CS.Berkeley.EDU> To: freebsd-hackers@freebsd.org Subject: strange mmap programming bug Date: Wed, 12 Jun 1996 02:58:28 -0700 Sender: owner-hackers@freebsd.org X-Loop: FreeBSD.org Precedence: bulk I'm having this problem. I don't know if its only on FreeBSD or not, as I have only experienced it on FreeBSD and its hard to reproduce. Occasionally, when a program of mine exits abnormally, it seems that small files which were opened O_RDONLY and then mmaped are being modified. I am mmaping the entire file. I have only noticed this for files smaller than PAGESIZE. The file's length is changed to be exactly 4096 bytes with zero's padding the original data. Basically, its fd = open(filename, O_RDONLY) fstat(fd, &sbuf) mmap(0, sbuf.st_size, PROT_READ, MAP_PRIVATE, fd, 0) with the appropriate error checks. Does anyone have an idea what could be happening? -josh