patch-2.1.93 linux/fs/devpts/root.c

• Lines: 170
• Date: Sat Apr 4 09:45:15 1998
• Orig file: v2.1.92/linux/fs/devpts/root.c
• Orig date: Wed Dec 31 16:00:00 1969

diff -u --recursive --new-file v2.1.92/linux/fs/devpts/root.c linux/fs/devpts/root.c
@@ -0,0 +1,169 @@
+/* -*- linux-c -*- --------------------------------------------------------- *
+ *
+ * linux/fs/devpts/root.c
+ *
+ *  Copyright 1998 H. Peter Anvin -- All Rights Reserved
+ *
+ * This file is part of the Linux kernel and is made available under
+ * the terms of the GNU General Public License, version 2, or at your
+ * option, any later version, incorporated herein by reference.
+ *
+ * ------------------------------------------------------------------------- */
+
+#include <linux/errno.h>
+#include <linux/stat.h>
+#include <linux/param.h>
+#include "devpts_i.h"
+
+static int devpts_root_readdir(struct file *,void *,filldir_t);
+static int devpts_root_lookup(struct inode *,struct dentry *);
+static int devpts_revalidate(struct dentry *);
+
+static struct file_operations devpts_root_operations = {
+	NULL,                   /* llseek */
+	NULL,                   /* read */
+	NULL,                   /* write */
+	devpts_root_readdir,    /* readdir */
+	NULL,                   /* poll */
+	NULL,			/* ioctl */
+	NULL,                   /* mmap */
+	NULL,                   /* open */
+	NULL,                   /* release */
+	NULL,			/* fsync */
+	NULL,			/* fasync */
+	NULL,			/* check_media_change */
+	NULL,			/* revalidate */
+	NULL			/* lock */
+};
+
+struct inode_operations devpts_root_inode_operations = {
+	&devpts_root_operations, /* file operations */
+	NULL,                   /* create */
+	devpts_root_lookup,     /* lookup */
+	NULL,                   /* link */
+	NULL,			/* unlink */
+	NULL,			/* symlink */
+	NULL,			/* mkdir */
+	NULL,			/* rmdir */
+	NULL,                   /* mknod */
+	NULL,                   /* rename */
+	NULL,                   /* readlink */
+	NULL,                   /* follow_link */
+	NULL,                   /* readpage */
+	NULL,                   /* writepage */
+	NULL,                   /* bmap */
+	NULL,                   /* truncate */
+	NULL,			/* permission */
+	NULL,			/* smap */
+	NULL,			/* updatepage */
+	NULL			/* revalidate */
+};
+
+static struct dentry_operations devpts_dentry_operations = {
+	devpts_revalidate,	/* d_revalidate */
+	NULL,			/* d_hash */
+	NULL,			/* d_compare */
+};
+
+/*
+ * The normal naming convention is simply /dev/pts/<number>; this conforms
+ * to the System V naming convention
+ */
+
+#define genptsname(buf,num) sprintf(buf, "%d", num)
+
+static int devpts_root_readdir(struct file *filp, void *dirent, filldir_t filldir)
+{
+	struct inode * inode = filp->f_dentry->d_inode;
+	struct devpts_sb_info * sbi = SBI(filp->f_dentry->d_inode->i_sb);
+	off_t nr;
+	char numbuf[16];
+
+	if (!inode || !S_ISDIR(inode->i_mode))
+		return -ENOTDIR;
+
+	nr = filp->f_pos;
+
+	switch(nr)
+	{
+	case 0:
+		if (filldir(dirent, ".", 1, nr, inode->i_ino) < 0)
+			return 0;
+		filp->f_pos = ++nr;
+		/* fall through */
+	case 1:
+		if (filldir(dirent, "..", 2, nr, inode->i_ino) < 0)
+			return 0;
+		filp->f_pos = ++nr;
+		/* fall through */
+	default:
+		while ( nr < NR_PTYS+2 ) {
+			int ptynr = nr - 2;
+			if ( sbi->inodes[ptynr] ) {
+				genptsname(numbuf, ptynr);
+				if ( filldir(dirent, numbuf, strlen(numbuf), nr, nr) < 0 )
+					return 0;
+			}
+			filp->f_pos = ++nr;
+		}
+		break;
+	}
+
+	return 0;
+}
+
+/*
+ * Revalidate is called on every cache lookup.  We use it to check that
+ * the pty really does still exist.  Never revalidate negative dentries;
+ * for simplicity (fix later?)
+ */
+static int devpts_revalidate(struct dentry * dentry)
+{
+	struct devpts_sb_info *sbi;
+
+	if ( !dentry->d_inode )
+		return 0;
+
+	sbi = SBI(dentry->d_inode->i_sb);
+
+	return ( sbi->inodes[dentry->d_inode->i_ino - 2] == dentry->d_inode );
+}
+
+static int devpts_root_lookup(struct inode * dir, struct dentry * dentry)
+{
+	struct devpts_sb_info *sbi = SBI(dir->i_sb);
+	int entry, i;
+	const char *p;
+
+	if (!S_ISDIR(dir->i_mode))
+		return -ENOTDIR;
+
+	dentry->d_inode = NULL;	/* Assume failure */
+	dentry->d_op    = &devpts_dentry_operations;
+
+	if ( dentry->d_name.len == 1 && dentry->d_name.name[0] == '0' ) {
+		entry = 0;
+	} else if ( dentry->d_name.len < 1 ) {
+		return 0;
+	} else {
+		p = dentry->d_name.name;
+		if ( *p < '1' || *p > '9' )
+			return 0;
+		entry = *p++ - '0';
+
+		for ( i = dentry->d_name.len-1 ; i ; i-- ) {
+			if ( *p < '0' || *p > '9' )
+				return 0;
+			entry *= 10;
+			entry += (*p++ - '0');
+		}
+	}
+	
+	dentry->d_inode = sbi->inodes[entry];
+	if ( dentry->d_inode )
+		dentry->d_inode->i_count++;
+
+	d_add(dentry, dentry->d_inode);
+
+	return 0;
+}