lib/libfdt/fdt.c

   1 /*
   2  * libfdt - Flat Device Tree manipulation
   3  * Copyright (C) 2006 David Gibson, IBM Corporation.
   4  * SPDX-License-Identifier:     GPL-2.0+ BSD-2-Clause
   5  */
   6 #include <libfdt_env.h>
   7
   8 #ifndef USE_HOSTCC
   9 #include <fdt.h>
  10 #include <libfdt.h>
  11 #else
  12 #include "fdt_host.h"
  13 #endif
  14
  15 #include "libfdt_internal.h"
  16
  17 int fdt_check_header(const void *fdt)
  18 {
  19         if (fdt_magic(fdt) == FDT_MAGIC) {
  20                 /* Complete tree */
  21                 if (fdt_version(fdt) < FDT_FIRST_SUPPORTED_VERSION)
  22                         return -FDT_ERR_BADVERSION;
  23                 if (fdt_last_comp_version(fdt) > FDT_LAST_SUPPORTED_VERSION)
  24                         return -FDT_ERR_BADVERSION;
  25         } else if (fdt_magic(fdt) == FDT_SW_MAGIC) {
  26                 /* Unfinished sequential-write blob */
  27                 if (fdt_size_dt_struct(fdt) == 0)
  28                         return -FDT_ERR_BADSTATE;
  29         } else {
  30                 return -FDT_ERR_BADMAGIC;
  31         }
  32
  33         return 0;
  34 }
  35
  36 const void *fdt_offset_ptr(const void *fdt, int offset, unsigned int len)
  37 {
  38         const char *p;
  39
  40         if (fdt_version(fdt) >= 0x11)
  41                 if (((offset + len) < offset)
  42                     || ((offset + len) > fdt_size_dt_struct(fdt)))
  43                         return NULL;
  44
  45         p = _fdt_offset_ptr(fdt, offset);
  46
  47         if (p + len < p)
  48                 return NULL;
  49         return p;
  50 }
  51
  52 uint32_t fdt_next_tag(const void *fdt, int startoffset, int *nextoffset)
  53 {
  54         const fdt32_t *tagp, *lenp;
  55         uint32_t tag;
  56         int offset = startoffset;
  57         const char *p;
  58
  59         *nextoffset = -FDT_ERR_TRUNCATED;
  60         tagp = fdt_offset_ptr(fdt, offset, FDT_TAGSIZE);
  61         if (!tagp)
  62                 return FDT_END; /* premature end */
  63         tag = fdt32_to_cpu(*tagp);
  64         offset += FDT_TAGSIZE;
  65
  66         *nextoffset = -FDT_ERR_BADSTRUCTURE;
  67         switch (tag) {
  68         case FDT_BEGIN_NODE:
  69                 /* skip name */
  70                 do {
  71                         p = fdt_offset_ptr(fdt, offset++, 1);
  72                 } while (p && (*p != '\0'));
  73                 if (!p)
  74                         return FDT_END; /* premature end */
  75                 break;
  76
  77         case FDT_PROP:
  78                 lenp = fdt_offset_ptr(fdt, offset, sizeof(*lenp));
  79                 if (!lenp)
  80                         return FDT_END; /* premature end */
  81                 /* skip-name offset, length and value */
  82                 offset += sizeof(struct fdt_property) - FDT_TAGSIZE
  83                         + fdt32_to_cpu(*lenp);
  84                 break;
  85
  86         case FDT_END:
  87         case FDT_END_NODE:
  88         case FDT_NOP:
  89                 break;
  90
  91         default:
  92                 return FDT_END;
  93         }
  94
  95         if (!fdt_offset_ptr(fdt, startoffset, offset - startoffset))
  96                 return FDT_END; /* premature end */
  97
  98         *nextoffset = FDT_TAGALIGN(offset);
  99         return tag;
 100 }
 101
 102 int _fdt_check_node_offset(const void *fdt, int offset)
 103 {
 104         if ((offset < 0) || (offset % FDT_TAGSIZE)
 105             || (fdt_next_tag(fdt, offset, &offset) != FDT_BEGIN_NODE))
 106                 return -FDT_ERR_BADOFFSET;
 107
 108         return offset;
 109 }
 110
 111 int _fdt_check_prop_offset(const void *fdt, int offset)
 112 {
 113         if ((offset < 0) || (offset % FDT_TAGSIZE)
 114             || (fdt_next_tag(fdt, offset, &offset) != FDT_PROP))
 115                 return -FDT_ERR_BADOFFSET;
 116
 117         return offset;
 118 }
 119
 120 int fdt_next_node(const void *fdt, int offset, int *depth)
 121 {
 122         int nextoffset = 0;
 123         uint32_t tag;
 124
 125         if (offset >= 0)
 126                 if ((nextoffset = _fdt_check_node_offset(fdt, offset)) < 0)
 127                         return nextoffset;
 128
 129         do {
 130                 offset = nextoffset;
 131                 tag = fdt_next_tag(fdt, offset, &nextoffset);
 132
 133                 switch (tag) {
 134                 case FDT_PROP:
 135                 case FDT_NOP:
 136                         break;
 137
 138                 case FDT_BEGIN_NODE:
 139                         if (depth)
 140                                 (*depth)++;
 141                         break;
 142
 143                 case FDT_END_NODE:
 144                         if (depth && ((--(*depth)) < 0))
 145                                 return nextoffset;
 146                         break;
 147
 148                 case FDT_END:
 149                         if ((nextoffset >= 0)
 150                             || ((nextoffset == -FDT_ERR_TRUNCATED) && !depth))
 151                                 return -FDT_ERR_NOTFOUND;
 152                         else
 153                                 return nextoffset;
 154                 }
 155         } while (tag != FDT_BEGIN_NODE);
 156
 157         return offset;
 158 }
 159
 160 int fdt_first_subnode(const void *fdt, int offset)
 161 {
 162         int depth = 0;
 163
 164         offset = fdt_next_node(fdt, offset, &depth);
 165         if (offset < 0 || depth != 1)
 166                 return -FDT_ERR_NOTFOUND;
 167
 168         return offset;
 169 }
 170
 171 int fdt_next_subnode(const void *fdt, int offset)
 172 {
 173         int depth = 1;
 174
 175         /*
 176          * With respect to the parent, the depth of the next subnode will be
 177          * the same as the last.
 178          */
 179         do {
 180                 offset = fdt_next_node(fdt, offset, &depth);
 181                 if (offset < 0 || depth < 1)
 182                         return -FDT_ERR_NOTFOUND;
 183         } while (depth > 1);
 184
 185         return offset;
 186 }
 187
 188 const char *_fdt_find_string(const char *strtab, int tabsize, const char *s)
 189 {
 190         int len = strlen(s) + 1;
 191         const char *last = strtab + tabsize - len;
 192         const char *p;
 193
 194         for (p = strtab; p <= last; p++)
 195                 if (memcmp(p, s, len) == 0)
 196                         return p;
 197         return NULL;
 198 }
 199
 200 int fdt_move(const void *fdt, void *buf, int bufsize)
 201 {
 202         FDT_CHECK_HEADER(fdt);
 203
 204         if (fdt_totalsize(fdt) > bufsize)
 205                 return -FDT_ERR_NOSPACE;
 206
 207         memmove(buf, fdt, fdt_totalsize(fdt));
 208         return 0;
 209 }