From c9723a965ff6f5bf431bd43e7c637c1593ab9e3a Mon Sep 17 00:00:00 2001
From: Ken Thompson <ken@research.uucp>
Date: Fri, 18 Jul 1975 04:09:14 -0500
Subject: [PATCH] Research V6 development Work on file usr/sys/ken/nami.c

Synthesized-from: v6
---
 usr/sys/ken/nami.c | 200 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 200 insertions(+)
 create mode 100644 usr/sys/ken/nami.c

diff --git a/usr/sys/ken/nami.c b/usr/sys/ken/nami.c
new file mode 100644
index 0000000000..42a82b1dc8
--- /dev/null
+++ b/usr/sys/ken/nami.c
@@ -0,0 +1,200 @@
+#
+#include "../param.h"
+#include "../inode.h"
+#include "../user.h"
+#include "../systm.h"
+#include "../buf.h"
+
+/*
+ * Convert a pathname into a pointer to
+ * an inode. Note that the inode is locked.
+ *
+ * func = function called to get next char of name
+ *	&uchar if name is in user space
+ *	&schar if name is in system space
+ * flag = 0 if name is sought
+ *	1 if name is to be created
+ *	2 if name is to be deleted
+ */
+namei(func, flag)
+int (*func)();
+{
+	register struct inode *dp;
+	register c;
+	register char *cp;
+	int eo, *bp;
+
+	/*
+	 * If name starts with '/' start from
+	 * root; otherwise start from current dir.
+	 */
+
+	dp = u.u_cdir;
+	if((c=(*func)()) == '/')
+		dp = rootdir;
+	iget(dp->i_dev, dp->i_number);
+	while(c == '/')
+		c = (*func)();
+	if(c == '\0' && flag != 0) {
+		u.u_error = ENOENT;
+		goto out;
+	}
+
+cloop:
+	/*
+	 * Here dp contains pointer
+	 * to last component matched.
+	 */
+
+	if(u.u_error)
+		goto out;
+	if(c == '\0')
+		return(dp);
+
+	/*
+	 * If there is another component,
+	 * dp must be a directory and
+	 * must have x permission.
+	 */
+
+	if((dp->i_mode&IFMT) != IFDIR) {
+		u.u_error = ENOTDIR;
+		goto out;
+	}
+	if(access(dp, IEXEC))
+		goto out;
+
+	/*
+	 * Gather up name into
+	 * users' dir buffer.
+	 */
+
+	cp = &u.u_dbuf[0];
+	while(c!='/' && c!='\0' && u.u_error==0) {
+		if(cp < &u.u_dbuf[DIRSIZ])
+			*cp++ = c;
+		c = (*func)();
+	}
+	while(cp < &u.u_dbuf[DIRSIZ])
+		*cp++ = '\0';
+	while(c == '/')
+		c = (*func)();
+	if(u.u_error)
+		goto out;
+
+	/*
+	 * Set up to search a directory.
+	 */
+
+	u.u_offset[1] = 0;
+	u.u_offset[0] = 0;
+	u.u_segflg = 1;
+	eo = 0;
+	u.u_count = ldiv(dp->i_size1, DIRSIZ+2);
+	bp = NULL;
+
+eloop:
+
+	/*
+	 * If at the end of the directory,
+	 * the search failed. Report what
+	 * is appropriate as per flag.
+	 */
+
+	if(u.u_count == 0) {
+		if(bp != NULL)
+			brelse(bp);
+		if(flag==1 && c=='\0') {
+			if(access(dp, IWRITE))
+				goto out;
+			u.u_pdir = dp;
+			if(eo)
+				u.u_offset[1] = eo-DIRSIZ-2; else
+				dp->i_flag =| IUPD;
+			return(NULL);
+		}
+		u.u_error = ENOENT;
+		goto out;
+	}
+
+	/*
+	 * If offset is on a block boundary,
+	 * read the next directory block.
+	 * Release previous if it exists.
+	 */
+
+	if((u.u_offset[1]&0777) == 0) {
+		if(bp != NULL)
+			brelse(bp);
+		bp = bread(dp->i_dev,
+			bmap(dp, ldiv(u.u_offset[1], 512)));
+	}
+
+	/*
+	 * Note first empty directory slot
+	 * in eo for possible creat.
+	 * String compare the directory entry
+	 * and the current component.
+	 * If they do not match, go back to eloop.
+	 */
+
+	bcopy(bp->b_addr+(u.u_offset[1]&0777), &u.u_dent, (DIRSIZ+2)/2);
+	u.u_offset[1] =+ DIRSIZ+2;
+	u.u_count--;
+	if(u.u_dent.u_ino == 0) {
+		if(eo == 0)
+			eo = u.u_offset[1];
+		goto eloop;
+	}
+	for(cp = &u.u_dbuf[0]; cp < &u.u_dbuf[DIRSIZ]; cp++)
+		if(*cp != cp[u.u_dent.u_name - u.u_dbuf])
+			goto eloop;
+
+	/*
+	 * Here a component matched in a directory.
+	 * If there is more pathname, go back to
+	 * cloop, otherwise return.
+	 */
+
+	if(bp != NULL)
+		brelse(bp);
+	if(flag==2 && c=='\0') {
+		if(access(dp, IWRITE))
+			goto out;
+		return(dp);
+	}
+	bp = dp->i_dev;
+	iput(dp);
+	dp = iget(bp, u.u_dent.u_ino);
+	if(dp == NULL)
+		return(NULL);
+	goto cloop;
+
+out:
+	iput(dp);
+	return(NULL);
+}
+
+/*
+ * Return the next character from the
+ * kernel string pointed at by dirp.
+ */
+schar()
+{
+
+	return(*u.u_dirp++ & 0377);
+}
+
+/*
+ * Return the next character from the
+ * user string pointed at by dirp.
+ */
+uchar()
+{
+	register c;
+
+	c = fubyte(u.u_dirp++);
+	if(c == -1)
+		u.u_error = EFAULT;
+	return(c);
+}
-- 
2.20.1