xnu-3248.50.21.tar.gz

[apple/xnu.git] / bsd / hfs / hfs_catalog.c

diff --git a/bsd/hfs/hfs_catalog.c b/bsd/hfs/hfs_catalog.c
index 8e0a65c4f2294c22ee703276a144f62213a06c1e..0069ac2d425a16e37d5e413adaf83b08d3b02152 100644 (file)
--- a/bsd/hfs/hfs_catalog.c
+++ b/bsd/hfs/hfs_catalog.c
@@ -3057,6 +3057,7 @@ exit:
 }
 
 #define SMALL_DIRENTRY_SIZE  (int)(sizeof(struct dirent) - (MAXNAMLEN + 1) + 8)
+#define MAX_LINKINFO_ENTRIES 3000
 
 /*
  * Callback to pack directory entries.
@@ -3523,12 +3524,13 @@ cat_getdirentries(struct hfsmount *hfsmp, u_int32_t entrycnt, directoryhint_t *d
        struct packdirentry_state state;
        void * buffer;
        int bufsize;
+       
        int maxlinks;
        int result;
        int index;
        int have_key;
        int extended;
-       
+
        extended = flags & VNODE_READDIR_EXTENDED;
        
        if (extended && (hfsmp->hfs_flags & HFS_STANDARD)) {
@@ -3537,10 +3539,23 @@ cat_getdirentries(struct hfsmount *hfsmp, u_int32_t entrycnt, directoryhint_t *d
        fcb = hfsmp->hfs_catalog_cp->c_datafork;
 
        /*
-        * Get a buffer for link info array, btree iterator and a direntry:
+        * Get a buffer for link info array, btree iterator and a direntry.
+        * 
+        * We impose an cap of 3000 link entries when trying to compute
+        * the total number of hardlink entries that we'll allow in the  
+        * linkinfo array. 
+        *
+        * Note that in the case where there are very few hardlinks,
+        * this does not restrict or prevent us from vending out as many entries
+        * as we can to the uio_resid, because the getdirentries callback
+        * uiomoves the directory entries to the uio itself and does not use
+        * this MALLOC'd array. It also limits itself to maxlinks of hardlinks.
         */
-       maxlinks = MIN(entrycnt, (u_int32_t)(uio_resid(uio) / SMALL_DIRENTRY_SIZE));
-       bufsize = MAXPATHLEN + (maxlinks * sizeof(linkinfo_t)) + sizeof(*iterator);
+
+       /* Now compute the maximum link array size */
+       maxlinks = MIN (entrycnt, MAX_LINKINFO_ENTRIES);
+
+       bufsize = MAXPATHLEN + (maxlinks * sizeof(linkinfo_t)) + sizeof(*iterator); 
        if (extended) {
                bufsize += 2*sizeof(struct direntry);
        }