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Date: Mon, 18 Jan 2010 10:17:48 +0900 From: OGAWA Hirofumi <hirofumi@...l.parknet.co.jp> To: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com> Cc: Wu Fengguang <fengguang.wu@...el.com>, Andrew Morton <akpm@...ux-foundation.org>, Al Viro <viro@...iv.linux.org.uk>, Heiko Carstens <heiko.carstens@...ibm.com>, Christoph Hellwig <hch@...radead.org>, LKML <linux-kernel@...r.kernel.org>, Eric Paris <eparis@...hat.com>, Nick Piggin <npiggin@...e.de>, Andi Kleen <andi@...stfloor.org>, David Howells <dhowells@...hat.com>, Jonathan Corbet <corbet@....net>, <linux-fsdevel@...r.kernel.org> Subject: Re: [PATCH 6/6] vfs: introduce FMODE_NEG_OFFSET for allowing negative f_pos KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com> writes: >> > +static int >> > +__negative_fpos_check(struct file *file, loff_t pos, size_t count) >> > +{ >> > + /* >> > + * pos or pos+count is negative here, check overflow. >> > + * too big "count" will be caught in rw_verify_area(). >> > + */ >> > + if ((pos < 0) && (pos + count < pos)) >> > + return -EOVERFLOW; >> > + if (file->f_mode & FMODE_NEG_OFFSET) >> > + return 0; >> > + return -EINVAL; >> > +} >> > + >> > /* >> > * rw_verify_area doesn't like huge counts. We limit >> > * them to something that fits in "int" so that others >> > @@ -222,8 +236,11 @@ int rw_verify_area(int read_write, struc >> > if (unlikely((ssize_t) count < 0)) >> > return retval; >> > pos = *ppos; >> > - if (unlikely((pos < 0) || (loff_t) (pos + count) < 0)) >> > - return retval; >> > + if (unlikely((pos < 0) || (loff_t) (pos + count) < 0)) { >> > + retval = __negative_fpos_check(file, pos, count); >> > + if (retval) >> > + return retval; >> > + } >> > >> > if (unlikely(inode->i_flock && mandatory_lock(inode))) { >> > retval = locks_mandatory_area( >> >> Um... How do lseek() work? It sounds like to violate error code range. > > This is for read-write. As far as I know, > - generic_file_llseek, > - default_llseek > - no_llseek > > doesn't call this function. It seems to allow to set negative value to ->f_pos, right? So, lseek() returns (uses) it? Thanks. -- OGAWA Hirofumi <hirofumi@...l.parknet.co.jp> -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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