uevent.c

   1 /*******************************************************************************
   2 this code is protected by the GNU affero GPLv3
   3 author:Sylvain BERTRAND <sylvain.bertrand AT gmail dot com>
   4 *******************************************************************************/
   5 #include <blkid/blkid.h>
   6
   7 #include <ulinux/compiler_types.h>
   8 #include <ulinux/types.h>
   9 #include <ulinux/error.h>
  10 #include <ulinux/utils/mem.h>
  11 #include <ulinux/utils/ascii/string/string.h>
  12 #include <ulinux/utils/ascii/string/conv/decimal/decimal.h>
  13 #include <ulinux/sysc.h>
  14
  15 #include "out.h"
  16 #include "ulinux_namespace.h"
  17 #include "globals.h"
  18
  19 static u8 hdr_action_is_add(u8 *hdr)
  20 {
  21   #define HDR_ACTION_ADD "add@"
  22   if(memcmp(hdr,HDR_ACTION_ADD,sizeof(HDR_ACTION_ADD)-1)) return 0;
  23   return 1;
  24 }
  25
  26 static void hdr_skip(u8 **p)
  27 {
  28   loop if(*(*p)++==0) break;
  29 }
  30 #define var_skip hdr_skip
  31
  32 static u8 key_is_subsystem(u8 *p)
  33 {
  34   #define KEY_SUBSYSTEM "SUBSYSTEM="
  35   if(memcmp(p,KEY_SUBSYSTEM,sizeof(KEY_SUBSYSTEM)-1)) return 0;
  36   return 1;
  37 }
  38
  39 static u8 key_is_devname(u8 *p)
  40 {
  41   #define KEY_DEVNAME "DEVNAME="
  42   if(memcmp(p,KEY_DEVNAME,sizeof(KEY_DEVNAME)-1)) return 0;
  43   return 1;
  44 }
  45
  46 static void move_to_value(u8 **p)
  47 {
  48   loop if(*(*p)++=='=') break;
  49 }
  50
  51 static u8 value_is_block(u8 *p)
  52 {
  53   #define VALUE_BLOCK "block"
  54   if(!*p||memcmp(p,VALUE_BLOCK,sizeof(VALUE_BLOCK)-1)) return 0;
  55   return 1;
  56 }
  57
  58 static void value_skip(u8 **p)
  59 {
  60   loop if(*(*p)++==0) break;
  61 }
  62
  63 static void value_str_consume(u8 **p,u8 *d)
  64 {
  65   loop{
  66     *d++=**p;
  67     if(*(*p)++==0) break;
  68   }
  69 }
  70
  71 #define IS_ROOT     1
  72 #define IS_NOT_ROOT 0
  73 /*the block device is in devtmpfs, use it to probe with libblkid*/
  74 static u8 blk_dev_probe(u8 *dev_name)
  75 {
  76   /*the right way to do it is to query the limits on the /dev file system*/
  77   u8 dev_path[ROOT_DEV_PATH_SZ]="/dev/";
  78   blkid_probe pr;
  79   u8 r0;
  80   i r1;
  81   const char *type;
  82   const char *uuid;
  83
  84   r0=IS_NOT_ROOT;
  85
  86   strcat(dev_path,dev_name);
  87
  88   OUT(PRE "probing %s...\n",dev_path);
  89   pr=blkid_new_probe_from_filename((const char *)dev_path);
  90   if(!pr){
  91     OUT(PRE "failed (unable to create a blkid probe), skipping\n");
  92     return IS_NOT_ROOT;
  93   }
  94
  95   r1=blkid_do_probe(pr);
  96   if(r1!=0){
  97     OUT(PRE "failed (unable to perform the blkid probe), skipping\n");
  98     goto free_probe;
  99   }
 100
 101   r1=blkid_probe_lookup_value(pr,"TYPE",&type,0);
 102   if(r1!=0){
 103     OUT(PRE "failed (missing blkid type tag), skipping\n");
 104     goto free_probe;
 105   }
 106   OUT(PRE "  type=%s\n",type);
 107
 108   r1=blkid_probe_lookup_value(pr,"UUID",&uuid,0);
 109   if(r1!=0){
 110     OUT(PRE "failed (missing blkid uuid tag), skipping\n");
 111     goto free_probe;
 112   }
 113   OUT(PRE "  uuid=%s\n",uuid);
 114
 115   if(strcmp(uuid,root_uuid)==0){
 116     /*found the root filesystem*/
 117     OUT(PRE "found root\n");
 118     strcpy(root_dev_path,dev_path);
 119     strcpy(root_fs_type,type);
 120     r0=IS_ROOT;
 121   }
 122
 123   OUT(PRE "done\n");
 124 free_probe:
 125   blkid_free_probe(pr);
 126   return r0;
 127 }
 128
 129 /*here we are actually looking for block devices*/
 130 u8 uevent_process(u8 *p,i sz)
 131 {
 132   u8 *p_end;
 133   u8 dev_name[256];/*usually a devtmpfs which has path components of 256 bytes*/
 134   u8 r;
 135
 136   r=ROOT_NOT_FOUND;
 137   if(!hdr_action_is_add(p)) return r;
 138   p_end=p+sz;
 139   hdr_skip(&p);
 140
 141   memset(dev_name,0,sizeof(dev_name));
 142
 143   loop{
 144     if(p>=p_end) break;
 145
 146     if(key_is_subsystem(p)){
 147       move_to_value(&p);
 148       if(!value_is_block(p)) goto exit;
 149       else value_skip(&p);
 150     }else if(key_is_devname(p)){
 151       move_to_value(&p);
 152       value_str_consume(&p,dev_name);
 153     }else var_skip(&p);
 154   }
 155
 156   /*from here, we are dealing with a block device, may be our root*/
 157   r=blk_dev_probe(dev_name);
 158
 159 exit:
 160   return r;
 161 }