In fs.c, return an error if an element is longer than DIRSIZ.

The old code would truncate element names to DIRSIZ and leave out NULL. The new ns code, however, depends on NULL terminated strings.

In fs.c, return an error if an element is longer than DIRSIZ.
e38872d3 · Silas Boyd-Wickizer · abcc56d3 · e38872d3 · e38872d3
--- a/TODO
+++ b/TODO
+* stat.size is u32
 * get gcc asm labels working for cpu, proc, kmem
  - (I couldn't stop gcc from generating RIP-relative movs)
 * get something like asm labels working in clang
  - (is there a way to use address_space(256) attributes?)
 * on real hw, apicid != logical ID, but this breaks things.
-* allocate memory using PBASE
-  - adjust p2v and v2p
-* bring mtrace back
 * finish syscall/sysret implementation
 * make uart console work over IPMI SOL
 * make syslinux/pxelinux work over IPMI SOL

--- a/fs.c
+++ b/fs.c
@@ -667,10 +667,13 @@ dirlink(struct inode *dp, char *name, u32 inum)
 // Paths

 // Copy the next path element from path into name.
-// Return a pointer to the element following the copied one.
+// Update the pointer to the element following the copied one.
 // The returned path has no leading slashes,
 // so the caller can check *path=='\0' to see if the name is the last one.
+// 
+// If copied into name, return 1.
 // If no name to remove, return 0.
+// If the name is longer than DIRSIZ, return -1;
 //
 // Examples:
 //   skipelem("a/bb/c", name) = "bb/c", setting name = "a"
@@ -678,9 +681,10 @@ dirlink(struct inode *dp, char *name, u32 inum)
 //   skipelem("a", name) = "", setting name = "a"
 //   skipelem("", name) = skipelem("////", name) = 0
 //
-static char*
-skipelem(char *path, char *name)
+static int
+skipelem(char **rpath, char *name)
 {
+  char *path = *rpath;
  char *s;
  int len;

@@ -693,14 +697,15 @@ skipelem(char *path, char *name)
    path++;
  len = path - s;
  if(len >= DIRSIZ)
-    memmove(name, s, DIRSIZ);
+    return -1;
  else {
    memmove(name, s, len);
    name[len] = 0;
  }
  while(*path == '/')
    path++;
-  return path;
+  *rpath = path;
+  return 1;
 }

 // Look up and return the inode for a path name.
@@ -710,8 +715,7 @@ static struct inode*
 namex(char *path, int nameiparent, char *name)
 {
  struct inode *ip, *next;
-
-  //cprintf("namex %s\n", path);
+  int r;

  gc_begin_epoch();
  if(*path == '/') 
@@ -719,7 +723,7 @@ namex(char *path, int nameiparent, char *name)
  else
    ip = idup(myproc()->cwd);

-  while((path = skipelem(path, name)) != 0){
+  while((r = skipelem(&path, name)) == 1){
    next = 0;
    if(next == 0){
      if(ip->type == 0)
@@ -743,7 +747,7 @@ namex(char *path, int nameiparent, char *name)
    }
    ip = next;
  }
-  if(nameiparent){
+  if(r == -1 || nameiparent){
    iput(ip);
    gc_end_epoch();
    return 0;