[PATCH 3/5] Refactoring of function nvlist_find_value

[Massimo Maggi]

It's needed to allow iteration of nvlists in other functions.

Ported to GRUB2 from IllumOS changeset 13700    2889e2596bd6

Author: Christopher Siden <address@hidden>
Ported-by: Massimo Maggi <address@hidden>
---
 grub-core/fs/zfs/zfs.c | 230
+++++++++++++++++++++++++++++++++----------------
 1 file changed, 158 insertions(+), 72 deletions(-)

diff --git a/grub-core/fs/zfs/zfs.c b/grub-core/fs/zfs/zfs.c
index 3ea9c95..7f76445 100644
--- a/grub-core/fs/zfs/zfs.c
+++ b/grub-core/fs/zfs/zfs.c
@@ -2,6 +2,7 @@
  *  GRUB  --  GRand Unified Bootloader
  *  Copyright (C) 1999,2000,2001,2002,2003,2004,2009,2010,2011  Free
Software Foundation, Inc.
  *  Copyright 2010  Sun Microsystems, Inc.
+ *  Copyright (c) 2012 by Delphix. All rights reserved.
  *
  *  GRUB is free software; you can redistribute it and/or modify
  *  it under the terms of the GNU General Public License as published by
@@ -768,6 +769,155 @@ fill_vdev_info (struct grub_zfs_data *data,
 }
  /*
+ * For a given XDR packed nvlist, verify the first 4 bytes and move on.
+ *
+ * An XDR packed nvlist is encoded as (comments from nvs_xdr_create) :
+ *
+ *      encoding method/host endian     (4 bytes)
+ *      nvl_version                     (4 bytes)
+ *      nvl_nvflag                      (4 bytes)
+ *     encoded nvpairs:
+ *             encoded size of the nvpair      (4 bytes)
+ *             decoded size of the nvpair      (4 bytes)
+ *             name string size                (4 bytes)
+ *             name string data                (sizeof(NV_ALIGN4(string))
+ *             data type                       (4 bytes)
+ *             # of elements in the nvpair     (4 bytes)
+ *             data
+ *      2 zero's for the last nvpair
+ *             (end of the entire list)        (8 bytes)
+ *
+ */
+
+/*
+ * The nvlist_next_nvpair() function returns a handle to the next
nvpair in the
+ * list following nvpair. If nvpair is NULL, the first pair is returned. If
+ * nvpair is the last pair in the nvlist, NULL is returned.
+ */
+static const char *
+nvlist_next_nvpair(const char *nvl, const char *nvpair)
+{
+       const char *nvp;
+       int encode_size;
+       int name_len;
+       if (nvl == NULL)
+               return (NULL);
+
+       if (nvpair == NULL) {
+               /* skip over header, nvl_version and nvl_nvflag */
+               nvpair = nvl + 4 * 3;
+       } else {
+               /* skip to the next nvpair */
+               encode_size = grub_be_to_cpu32 (grub_get_unaligned32(nvpair));
+               nvpair += encode_size;
+       }
+       /* 8 bytes of 0 marks the end of the list */
+       if (*(grub_uint64_t*)nvpair == 0)
+               return (NULL);
+       /*consistency checks*/
+       if (nvpair + 4 * 3 >= nvl + VDEV_PHYS_SIZE)
+       {
+         grub_dprintf ("zfs", "nvlist overflow\n");
+         grub_error (GRUB_ERR_BAD_FS, "incorrect nvlist");
+         return (NULL);
+       }
+       encode_size = grub_be_to_cpu32 (grub_get_unaligned32(nvpair));
+
+       nvp = nvpair + 4*2;
+       name_len = grub_be_to_cpu32 (grub_get_unaligned32 (nvp));
+       nvp += 4;
+
+       nvp = nvp + ((name_len + 3) & ~3); // align +   if (nvp + 4 >= nvl +
VDEV_PHYS_SIZE                        +     || encode_size < 0
+           || nvp + 4 + encode_size > nvl + VDEV_PHYS_SIZE)       +    {
+         grub_dprintf ("zfs", "nvlist overflow\n");
+         grub_error (GRUB_ERR_BAD_FS, "incorrect nvlist");
+         return (NULL);
+       }
+        /* end consistency checks */
+
+       return (nvpair);
+}
+/*
+ * This function returns 0 on success and 1 on failure. On success, a
string
+ * containing the name of nvpair is saved in buf.
+ */
+static int
+nvpair_name(const char *nvp, char **buf, int* buflen)
+{
+       int len;
+
+       /* skip over encode/decode size */
+       nvp += 4 * 2;
+
+       len = grub_be_to_cpu32 (grub_get_unaligned32 (nvp));
+       nvp=nvp+4;
+       
+       *buf=(char*)nvp;
+       *buflen=len;
+
+       return (0);
+}
+/*
+ * This function retrieves the value of the nvpair in the form of
enumerated
+ * type data_type_t.
+ */
+static int
+nvpair_type(const char *nvp)
+{
+       int name_len, type;
+
+       /* skip over encode/decode size */
+       nvp += 4 * 2;
+
+       /* skip over name_len */
+       name_len = grub_be_to_cpu32 (grub_get_unaligned32 (nvp));
+       nvp += 4;
+
+       /* skip over name */
+       nvp = nvp + ((name_len + 3) & ~3); /* align */
+
+       type = grub_be_to_cpu32 (grub_get_unaligned32 (nvp));
+
+       return (type);
+}
+static int
+nvpair_value(const char *nvp,char **val,
+                  grub_size_t *size_out, grub_size_t *nelm_out)
+{
+       int name_len,nelm,encode_size;
+
+       /* skip over encode/decode size */
+       encode_size = grub_be_to_cpu32 (grub_get_unaligned32(nvp));
+       nvp += 8;
+
+       /* skip over name_len */
+       name_len = grub_be_to_cpu32 (grub_get_unaligned32 (nvp));
+       nvp += 4;
+
+       /* skip over name */
+       nvp = nvp + ((name_len + 3) & ~3); /* align */
+       
+       /* skip over type */
+       nvp += 4;
+       nelm = grub_be_to_cpu32 (grub_get_unaligned32 (nvp));
+       nvp +=4;
+       if (nelm < 1)
+       {
+         grub_error (GRUB_ERR_BAD_FS, "empty nvpair");
+         return 0;
+       }
+         *val = (char *) nvp;
+         *size_out = encode_size;
+         if (nelm_out)
+           *nelm_out = nelm;
+           +   return 1;
+}
+
+/*
  * Check the disk label information and retrieve needed vdev name-value
pairs.
  *
  */
@@ -3064,34 +3214,14 @@ dnode_get_fullpath (const char *fullpath, struct
subvolume *subvol,
   return err;
 }
 -/*
- * For a given XDR packed nvlist, verify the first 4 bytes and move on.
- *
- * An XDR packed nvlist is encoded as (comments from nvs_xdr_create) :
- *
- *      encoding method/host endian     (4 bytes)
- *      nvl_version                     (4 bytes)
- *      nvl_nvflag                      (4 bytes)
- *     encoded nvpairs:
- *             encoded size of the nvpair      (4 bytes)
- *             decoded size of the nvpair      (4 bytes)
- *             name string size                (4 bytes)
- *             name string data                (sizeof(NV_ALIGN4(string))
- *             data type                       (4 bytes)
- *             # of elements in the nvpair     (4 bytes)
- *             data
- *      2 zero's for the last nvpair
- *             (end of the entire list)        (8 bytes)
- *
- */
-
 static int
 nvlist_find_value (const char *nvlist_in, const char *name,
                   int valtype, char **val,
                   grub_size_t *size_out, grub_size_t *nelm_out)
 {
-  int name_len, type, encode_size;
-  const char *nvpair, *nvp_name, *nvlist = nvlist_in;
+  int name_len, type ;
+  const char *nvpair=NULL,*nvlist=nvlist_in;
+  char *nvp_name;
    /* Verify if the 1st and 2nd byte in the nvlist are valid. */
   /* NOTE: independently of what endianness header announces all @@
-3104,62 +3234,18 @@ nvlist_find_value (const char *nvlist_in, const
char *name,
       return 0;
     }
 -  /* skip the header, nvl_version, and nvl_nvflag */
-  nvlist = nvlist + 4 * 3;
   /*
    * Loop thru the nvpair list
    * The XDR representation of an integer is in big-endian byte order.
    */
-  while ((encode_size = grub_be_to_cpu32 (grub_get_unaligned32 (nvlist))))
+  while ((nvpair=nvlist_next_nvpair(nvlist,nvpair)))
     {
-      int nelm;
-
-      if (nvlist + 4 * 4 >= nvlist_in + VDEV_PHYS_SIZE)
+      nvpair_name(nvpair,&nvp_name,&name_len);
+      type = nvpair_type(nvpair);
+      if ((grub_strncmp (nvp_name, name, grub_strlen(name)) == 0) &&
type == valtype)
        {
-         grub_dprintf ("zfs", "nvlist overflow\n");
-         grub_error (GRUB_ERR_BAD_FS, "incorrect nvlist");
-         return 0;
-       }
-
-      nvpair = nvlist + 4 * 2; /* skip the encode/decode size */
-
-      name_len = grub_be_to_cpu32 (grub_get_unaligned32 (nvpair));
-      nvpair += 4;
-
-      nvp_name = nvpair;
-      nvpair = nvpair + ((name_len + 3) & ~3); /* align */
-
-      if (nvpair + 8 >= nvlist_in + VDEV_PHYS_SIZE
-         || encode_size < 0
-         || nvpair + 8 + encode_size > nvlist_in + VDEV_PHYS_SIZE)
-       {
-         grub_dprintf ("zfs", "nvlist overflow\n");
-         grub_error (GRUB_ERR_BAD_FS, "incorrect nvlist");
-         return 0;
+         return nvpair_value(nvpair,val,size_out,nelm_out);
        }
-
-      type = grub_be_to_cpu32 (grub_get_unaligned32 (nvpair));
-      nvpair += 4;
-
-      nelm = grub_be_to_cpu32 (grub_get_unaligned32 (nvpair));
-      if (nelm < 1)
-       {
-         grub_error (GRUB_ERR_BAD_FS, "empty nvpair");
-         return 0;
-       }
-
-      nvpair += 4;
-
-      if ((grub_strncmp (nvp_name, name, name_len) == 0) && type ==
valtype)
-       {
-         *val = (char *) nvpair;
-         *size_out = encode_size;
-         if (nelm_out)
-           *nelm_out = nelm;
-         return 1;
-       }
-
-      nvlist += encode_size;   /* goto the next nvpair */
     }
   return 0;
 }
-- 
1.8.1.1

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