sanchayanmaity/xv6-cs450
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remove namelen parameter

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rsc 2007-08-21 19:58:55 +00:00
parent 0073beee52
commit fbf9103952
2 changed files with 82 additions and 71 deletions
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7
defs.h
View file

@ -121,24 +121,19 @@ void bwrite(struct buf*, uint);
void brelse(struct buf*); void brelse(struct buf*);
// fs.c // fs.c
struct inode;
void iinit(void); void iinit(void);
struct inode* iget(uint, uint);
void ilock(struct inode*); void ilock(struct inode*);
void iunlock(struct inode*); void iunlock(struct inode*);
void itrunc(struct inode*);
void idecref(struct inode*); void idecref(struct inode*);
struct inode* iincref(struct inode*); struct inode* iincref(struct inode*);
void iput(struct inode*); void iput(struct inode*);
struct inode* namei(char*); struct inode* namei(char*);
struct inode* nameiparent(char*, char**, int*);
void stati(struct inode*, struct stat*); void stati(struct inode*, struct stat*);
int readi(struct inode*, char*, uint, uint); int readi(struct inode*, char*, uint, uint);
int writei(struct inode*, char*, uint, uint); int writei(struct inode*, char*, uint, uint);
struct inode* mknod(char*, short, short, short); struct inode* mknod(char*, short, short, short);
struct inode* dircreat(struct inode*, char*, int, short, short, short);
struct inode* dirlookup(struct inode*, char*, int, uint*);
int unlink(char*); int unlink(char*);
void iupdate(struct inode*);
int link(char*, char*); int link(char*, char*);
struct inode* igetroot(void); struct inode* igetroot(void);
int mkdir(char *path); int mkdir(char *path);

146
fs.c
View file

@ -24,6 +24,8 @@
#include "dev.h" #include "dev.h"
#define min(a, b) ((a) < (b) ? (a) : (b)) #define min(a, b) ((a) < (b) ? (a) : (b))
static void itrunc(struct inode*);
static void iupdate(struct inode*);
// Blocks. // Blocks.
@ -278,7 +280,7 @@ ialloc(uint dev, short type)
} }
// Copy inode, which has changed, from memory to disk. // Copy inode, which has changed, from memory to disk.
void static void
iupdate(struct inode *ip) iupdate(struct inode *ip)
{ {
struct buf *bp; struct buf *bp;
@ -347,7 +349,7 @@ bmap(struct inode *ip, uint bn, int alloc)
} }
// Truncate inode (discard contents). // Truncate inode (discard contents).
void static void
itrunc(struct inode *ip) itrunc(struct inode *ip)
{ {
int i, j; int i, j;
@ -451,14 +453,41 @@ writei(struct inode *ip, char *src, uint off, uint n)
// //
// Directories are just inodes (files) filled with dirent structures. // Directories are just inodes (files) filled with dirent structures.
// Compare two names, which are strings with a max length of DIRSIZ.
static int
namecmp(const char *s, const char *t)
{
int i;
for(i=0; i<DIRSIZ; i++){
if(s[i] != t[i])
return s[i] - t[i];
if(s[i] == 0)
break;
}
return 0;
}
// Copy one name to another.
static void
namecpy(char *s, const char *t)
{
int i;
for(i=0; i<DIRSIZ && t[i]; i++)
s[i] = t[i];
for(; i<DIRSIZ; i++)
s[i] = 0;
}
// Look for a directory entry in a directory. // Look for a directory entry in a directory.
// If not found, return -1. // If not found, return -1.
// If found: // If found:
// set *poff to the byte offset of the directory entry // set *poff to the byte offset of the directory entry
// set *pinum to the inode number // set *pinum to the inode number
// return 0. // return 0.
struct inode* static struct inode*
dirlookup(struct inode *dp, char *name, int namelen, uint *poff) dirlookup(struct inode *dp, char *name, uint *poff)
{ {
uint off, inum; uint off, inum;
struct buf *bp; struct buf *bp;
@ -474,8 +503,7 @@ dirlookup(struct inode *dp, char *name, int namelen, uint *poff)
de++){ de++){
if(de->inum == 0) if(de->inum == 0)
continue; continue;
if(memcmp(name, de->name, namelen) == 0 && if(namecmp(name, de->name) == 0){
(namelen == DIRSIZ || de->name[namelen]== 0)){
// entry matches path element // entry matches path element
if(poff) if(poff)
*poff = off + (uchar*)de - bp->data; *poff = off + (uchar*)de - bp->data;
@ -491,15 +519,15 @@ dirlookup(struct inode *dp, char *name, int namelen, uint *poff)
// Write a new directory entry (name, ino) into the directory dp. // Write a new directory entry (name, ino) into the directory dp.
// Caller must have locked dp. // Caller must have locked dp.
int static int
dirlink(struct inode *dp, char *name, int namelen, uint ino) dirlink(struct inode *dp, char *name, uint ino)
{ {
int off; int off;
struct dirent de; struct dirent de;
struct inode *ip; struct inode *ip;
// Double-check that name is not present. // Double-check that name is not present.
if((ip = dirlookup(dp, name, namelen, 0)) != 0){ if((ip = dirlookup(dp, name, 0)) != 0){
idecref(ip); idecref(ip);
return -1; return -1;
} }
@ -512,11 +540,8 @@ dirlink(struct inode *dp, char *name, int namelen, uint ino)
break; break;
} }
namecpy(de.name, name);
de.inum = ino; de.inum = ino;
if(namelen > DIRSIZ)
namelen = DIRSIZ;
memmove(de.name, name, namelen);
memset(de.name+namelen, 0, DIRSIZ-namelen);
if(writei(dp, (char*)&de, off, sizeof(de)) != sizeof(de)) if(writei(dp, (char*)&de, off, sizeof(de)) != sizeof(de))
panic("dirwrite"); panic("dirwrite");
@ -526,8 +551,8 @@ dirlink(struct inode *dp, char *name, int namelen, uint ino)
// Create a new inode named name inside dp // Create a new inode named name inside dp
// and return its locked inode structure. // and return its locked inode structure.
// If name already exists, return 0. // If name already exists, return 0.
struct inode* static struct inode*
dircreat(struct inode *dp, char *name, int namelen, short type, short major, short minor) dircreat(struct inode *dp, char *name, short type, short major, short minor)
{ {
struct inode *ip; struct inode *ip;
@ -541,7 +566,7 @@ dircreat(struct inode *dp, char *name, int namelen, short type, short major, sho
ip->nlink = 1; ip->nlink = 1;
iupdate(ip); iupdate(ip);
if(dirlink(dp, name, namelen, ip->inum) < 0){ if(dirlink(dp, name, ip->inum) < 0){
ip->nlink = 0; ip->nlink = 0;
iupdate(ip); iupdate(ip);
iput(ip); iput(ip);
@ -568,16 +593,25 @@ dircreat(struct inode *dp, char *name, int namelen, short type, short major, sho
// skipelem("") = skipelem("////") = 0 // skipelem("") = skipelem("////") = 0
// //
static char* static char*
skipelem(char *path, char **name, int *len) skipelem(char *path, char *name)
{ {
char *s;
int len;
while(*path == '/') while(*path == '/')
path++; path++;
if(*path == 0) if(*path == 0)
return 0; return 0;
*name = path; s = path;
while(*path != '/' && *path != 0) while(*path != '/' && *path != 0)
path++; path++;
*len = path - *name; len = path - s;
if(len >= DIRSIZ)
memmove(name, s, DIRSIZ);
else{
memmove(name, s, len);
name[len] = 0;
}
while(*path == '/') while(*path == '/')
path++; path++;
return path; return path;
@ -593,11 +627,9 @@ skipelem(char *path, char **name, int *len)
// NAMEI_DELETE: return locked parent inode, offset of dirent in *ret_off. // NAMEI_DELETE: return locked parent inode, offset of dirent in *ret_off.
// return 0 if name doesn't exist. // return 0 if name doesn't exist.
struct inode* struct inode*
_namei(char *path, int parent, char **pname, int *pnamelen) _namei(char *path, int parent, char *name)
{ {
struct inode *dp, *ip; struct inode *dp, *ip;
char *name;
int namelen;
uint off; uint off;
if(*path == '/') if(*path == '/')
@ -606,22 +638,16 @@ _namei(char *path, int parent, char **pname, int *pnamelen)
dp = iincref(cp->cwd); dp = iincref(cp->cwd);
ilock(dp); ilock(dp);
while((path = skipelem(path, &name, &namelen)) != 0){ while((path = skipelem(path, name)) != 0){
// Truncate names in path to DIRSIZ chars.
if(namelen > DIRSIZ)
namelen = DIRSIZ;
if(dp->type != T_DIR) if(dp->type != T_DIR)
goto fail; goto fail;
if(parent && *path == '\0'){ if(parent && *path == '\0'){
// Stop one level early. // Stop one level early.
*pname = name;
*pnamelen = namelen;
return dp; return dp;
} }
if((ip = dirlookup(dp, name, namelen, &off)) == 0) if((ip = dirlookup(dp, name, &off)) == 0)
goto fail; goto fail;
iput(dp); iput(dp);
@ -642,29 +668,27 @@ fail:
struct inode* struct inode*
namei(char *path) namei(char *path)
{ {
return _namei(path, 0, 0, 0); char name[DIRSIZ];
return _namei(path, 0, name);
} }
struct inode* static struct inode*
nameiparent(char *path, char **name, int *namelen) nameiparent(char *path, char *name)
{ {
return _namei(path, 1, name, namelen); return _namei(path, 1, name);
} }
// Create the path and return its locked inode structure. // Create the path and return its locked inode structure.
// If cp already exists, return 0. // If cp already exists, return 0.
struct inode* struct inode*
mknod(char *path, short type, short major, short minor) mknod(char *path, short type, short major, short minor)
{ {
struct inode *ip, *dp; struct inode *ip, *dp;
char *name; char name[DIRSIZ];
int namelen;
if((dp = nameiparent(path, &name, &namelen)) == 0) if((dp = nameiparent(path, name)) == 0)
return 0; return 0;
ip = dircreat(dp, name, namelen, type, major, minor); ip = dircreat(dp, name, type, major, minor);
iput(dp); iput(dp);
return ip; return ip;
} }
@ -676,26 +700,21 @@ unlink(char *path)
struct inode *ip, *dp; struct inode *ip, *dp;
struct dirent de; struct dirent de;
uint off; uint off;
char *name; char name[DIRSIZ];
int namelen;
if((dp = nameiparent(path, &name, &namelen)) == 0) if((dp = nameiparent(path, name)) == 0)
return -1; return -1;
if((ip = dirlookup(dp, name, namelen, &off)) == 0){
// Cannot unlink "." or "..".
if(namecmp(name, ".") == 0 || namecmp(name, "..") == 0){
iput(dp); iput(dp);
return -1; return -1;
} }
if(readi(dp, (char*)&de, off, sizeof(de)) != sizeof(de) || de.inum == 0) if((ip = dirlookup(dp, name, &off)) == 0){
panic("unlink no entry");
// Cannot remove "." or ".." - the 2 and 3 count the trailing NUL.
if(memcmp(de.name, ".", 2) == 0 || memcmp(de.name, "..", 3) == 0){
idecref(ip);
iput(dp); iput(dp);
return -1; return -1;
} }
memset(&de, 0, sizeof(de)); memset(&de, 0, sizeof(de));
if(writei(dp, (char*)&de, off, sizeof(de)) != sizeof(de)) if(writei(dp, (char*)&de, off, sizeof(de)) != sizeof(de))
panic("unlink dir write"); panic("unlink dir write");
@ -716,8 +735,7 @@ int
link(char *old, char *new) link(char *old, char *new)
{ {
struct inode *ip, *dp; struct inode *ip, *dp;
char *name; char name[DIRSIZ];
int namelen;
if((ip = namei(old)) == 0) if((ip = namei(old)) == 0)
return -1; return -1;
@ -727,11 +745,11 @@ link(char *old, char *new)
} }
iunlock(ip); iunlock(ip);
if((dp = nameiparent(new, &name, &namelen)) == 0){ if((dp = nameiparent(new, name)) == 0){
idecref(ip); idecref(ip);
return -1; return -1;
} }
if(dp->dev != ip->dev || dirlink(dp, name, namelen, ip->inum) < 0){ if(dp->dev != ip->dev || dirlink(dp, name, ip->inum) < 0){
idecref(ip); idecref(ip);
iput(dp); iput(dp);
return -1; return -1;
@ -750,21 +768,20 @@ int
mkdir(char *path) mkdir(char *path)
{ {
struct inode *dp, *ip; struct inode *dp, *ip;
char *name; char name[DIRSIZ];
int namelen;
// XXX write ordering is screwy here- do we care? // XXX write ordering is screwy here- do we care?
if((dp = nameiparent(path, &name, &namelen)) == 0) if((dp = nameiparent(path, name)) == 0)
return -1; return -1;
if((ip = dircreat(dp, name, namelen, T_DIR, 0, 0)) == 0){ if((ip = dircreat(dp, name, T_DIR, 0, 0)) == 0){
iput(dp); iput(dp);
return -1; return -1;
} }
dp->nlink++; dp->nlink++;
iupdate(dp); iupdate(dp);
if(dirlink(ip, ".", 1, ip->inum) < 0 || dirlink(ip, "..", 2, dp->inum) < 0) if(dirlink(ip, ".", ip->inum) < 0 || dirlink(ip, "..", dp->inum) < 0)
panic("mkdir"); panic("mkdir");
iput(dp); iput(dp);
iput(ip); iput(ip);
@ -776,13 +793,12 @@ struct inode*
create(char *path) create(char *path)
{ {
struct inode *dp, *ip; struct inode *dp, *ip;
char *name; char name[DIRSIZ];
int namelen;
if((dp = nameiparent(path, &name, &namelen)) == 0) if((dp = nameiparent(path, name)) == 0)
return 0; return 0;
if((ip = dirlookup(dp, name, namelen, 0)) != 0){ if((ip = dirlookup(dp, name, 0)) != 0){
iput(dp); iput(dp);
ilock(ip); ilock(ip);
if(ip->type == T_DIR){ if(ip->type == T_DIR){
@ -791,7 +807,7 @@ create(char *path)
} }
return ip; return ip;
} }
if((ip = dircreat(dp, name, namelen, T_FILE, 0, 0)) == 0){ if((ip = dircreat(dp, name, T_FILE, 0, 0)) == 0){
iput(dp); iput(dp);
return 0; return 0;
} }