fs/fs_internal.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * 2017 by Marek Behun <marek.behun@nic.cz>
   4  *
   5  * Derived from code in ext4/dev.c, which was based on reiserfs/dev.c
   6  */
   7
   8 #define LOG_CATEGORY LOGC_CORE
   9
  10 #include <common.h>
  11 #include <blk.h>
  12 #include <compiler.h>
  13 #include <log.h>
  14 #include <part.h>
  15 #include <memalign.h>
  16
  17 int fs_devread(struct blk_desc *blk, struct disk_partition *partition,
  18                lbaint_t sector, int byte_offset, int byte_len, char *buf)
  19 {
  20         unsigned block_len;
  21         int log2blksz;
  22         ALLOC_CACHE_ALIGN_BUFFER(char, sec_buf, (blk ? blk->blksz : 0));
  23         if (blk == NULL) {
  24                 log_err("** Invalid Block Device Descriptor (NULL)\n");
  25                 return 0;
  26         }
  27         log2blksz = blk->log2blksz;
  28
  29         /* Check partition boundaries */
  30         if ((sector + ((byte_offset + byte_len - 1) >> log2blksz))
  31             >= partition->size) {
  32                 log_err("%s read outside partition " LBAFU "\n", __func__,
  33                         sector);
  34                 return 0;
  35         }
  36
  37         /* Get the read to the beginning of a partition */
  38         sector += byte_offset >> log2blksz;
  39         byte_offset &= blk->blksz - 1;
  40
  41         log_debug(" <" LBAFU ", %d, %d>\n", sector, byte_offset, byte_len);
  42
  43         if (byte_offset != 0) {
  44                 int readlen;
  45                 /* read first part which isn't aligned with start of sector */
  46                 if (blk_dread(blk, partition->start + sector, 1,
  47                               (void *)sec_buf) != 1) {
  48                         log_err(" ** %s read error **\n", __func__);
  49                         return 0;
  50                 }
  51                 readlen = min((int)blk->blksz - byte_offset,
  52                               byte_len);
  53                 memcpy(buf, sec_buf + byte_offset, readlen);
  54                 buf += readlen;
  55                 byte_len -= readlen;
  56                 sector++;
  57         }
  58
  59         if (byte_len == 0)
  60                 return 1;
  61
  62         /* read sector aligned part */
  63         block_len = byte_len & ~(blk->blksz - 1);
  64
  65         if (block_len == 0) {
  66                 ALLOC_CACHE_ALIGN_BUFFER(u8, p, blk->blksz);
  67
  68                 block_len = blk->blksz;
  69                 blk_dread(blk, partition->start + sector, 1,
  70                           (void *)p);
  71                 memcpy(buf, p, byte_len);
  72                 return 1;
  73         }
  74
  75         if (blk_dread(blk, partition->start + sector,
  76                       block_len >> log2blksz, (void *)buf) !=
  77                         block_len >> log2blksz) {
  78                 log_err(" ** %s read error - block\n", __func__);
  79                 return 0;
  80         }
  81         block_len = byte_len & ~(blk->blksz - 1);
  82         buf += block_len;
  83         byte_len -= block_len;
  84         sector += block_len / blk->blksz;
  85
  86         if (byte_len != 0) {
  87                 /* read rest of data which are not in whole sector */
  88                 if (blk_dread(blk, partition->start + sector, 1,
  89                               (void *)sec_buf) != 1) {
  90                         log_err("* %s read error - last part\n", __func__);
  91                         return 0;
  92                 }
  93                 memcpy(buf, sec_buf, byte_len);
  94         }
  95         return 1;
  96 }