util/nvramtool/cbfs.c

   1 /* SPDX-License-Identifier: GPL-2.0-only */
   2
   3 #ifdef __MINGW32__
   4 #include <winsock.h>
   5 #else
   6 #include <arpa/inet.h>
   7 #endif
   8 #include <sys/types.h>
   9 #include <sys/stat.h>
  10 #ifndef __MINGW32__
  11 #include <sys/mman.h>
  12 #endif
  13 #include <stdlib.h>
  14 #include <fcntl.h>
  15 #include <string.h>
  16 #include <stdio.h>
  17 #include "cbfs.h"
  18 #include "common.h"
  19
  20 #define ALIGN(x,a)              __ALIGN_MASK(x,(typeof(x))(a)-1)
  21 #define __ALIGN_MASK(x,mask)    (((x)+(mask))&~(mask))
  22
  23 static void *cbfs_mapped;
  24 static void *cbfs_offset;
  25 static void* virt_to_phys(u32 virt)
  26 {
  27         return cbfs_offset + virt;
  28 }
  29
  30 #ifdef DEBUG
  31 #define debug(x...) printf(x)
  32 #else
  33 #define debug(x...) while(0) {}
  34 #endif
  35
  36 static int cbfs_check_magic(struct cbfs_file *file)
  37 {
  38         return !strcmp(file->magic, CBFS_FILE_MAGIC) ? 1 : 0;
  39 }
  40
  41 static struct cbfs_header *cbfs_master_header(void)
  42 {
  43         struct cbfs_header *header;
  44
  45         void *ptr = virt_to_phys(*((u32*)virt_to_phys(CBFS_HEADPTR_ADDR)));
  46         debug("Check CBFS header at %p\n", ptr);
  47         header = (struct cbfs_header *) ptr;
  48
  49         debug("magic is %08x\n", ntohl(header->magic));
  50         if (ntohl(header->magic) != CBFS_HEADER_MAGIC) {
  51                 printf("ERROR: No valid CBFS header found!\n");
  52                 return NULL;
  53         }
  54
  55         debug("Found CBFS header at %p\n", ptr);
  56         return header;
  57 }
  58
  59 struct cbfs_file *cbfs_find(const char *name)
  60 {
  61         struct cbfs_header *header = cbfs_master_header();
  62         void *offset;
  63
  64         if (header == NULL)
  65                 return NULL;
  66         offset = virt_to_phys(0 - ntohl(header->romsize) + ntohl(header->offset));
  67
  68         int align= ntohl(header->align);
  69
  70         while(1) {
  71                 struct cbfs_file *file = (struct cbfs_file *) offset;
  72                 if (!cbfs_check_magic(file)) return NULL;
  73                 debug("Check %s\n", CBFS_NAME(file));
  74                 if (!strcmp(CBFS_NAME(file), name))
  75                         return file;
  76
  77                 int flen = ntohl(file->len);
  78                 int foffset = ntohl(file->offset);
  79                 debug("CBFS: follow chain: %p + %x + %x + align -> ", offset, foffset, flen);
  80
  81                 void *oldoffset = offset;
  82                 offset = (void*)ALIGN((uintptr_t)(offset + foffset + flen), align);
  83                 debug("%p\n", (void *)offset);
  84                 if (offset <= oldoffset) return NULL;
  85
  86                 if (offset < virt_to_phys(0xFFFFFFFF - ntohl(header->romsize)))
  87                         return NULL;
  88         }
  89 }
  90
  91 void *cbfs_find_file(const char *name, unsigned int type, unsigned int *len)
  92 {
  93         struct cbfs_file *file = cbfs_find(name);
  94
  95         if (file == NULL) {
  96                 printf("CBFS:  Could not find file %s\n",
  97                        name);
  98                 return NULL;
  99         }
 100
 101         if (ntohl(file->type) != type) {
 102                 printf("CBFS:  File %s is of type %x instead of"
 103                        "type %x\n", name, file->type, type);
 104
 105                 return NULL;
 106         }
 107         if (len != NULL) *len = file->len;
 108
 109         return (void *) CBFS_SUBHEADER(file);
 110 }
 111
 112 void open_cbfs(const char *filename)
 113 {
 114         struct stat cbfs_stat;
 115         int cbfs_fd;
 116
 117         cbfs_fd = open(filename, O_RDWR);
 118         if (cbfs_fd == -1) {
 119                 printf("Couldn't open '%s'\n", filename);
 120                 exit(-1);
 121         }
 122         if (fstat(cbfs_fd, &cbfs_stat) == -1) {
 123                 printf("Couldn't stat '%s'\n", filename);
 124                 exit(-1);
 125         }
 126         cbfs_mapped = mmap(NULL, cbfs_stat.st_size, PROT_READ | PROT_WRITE,
 127                         MAP_SHARED, cbfs_fd, 0);
 128         close(cbfs_fd);
 129         if (cbfs_mapped == MAP_FAILED) {
 130                 printf("Couldn't map '%s'\n", filename);
 131                 exit(-1);
 132         }
 133         cbfs_offset = cbfs_mapped-(0xffffffff-cbfs_stat.st_size+1);
 134 }