fs/fs_internal.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * 2017 by Marek Behún <kabel@kernel.org>
   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_debug("read outside partition " LBAFU "\n", sector);
  33                 return 0;
  34         }
  35
  36         /* Get the read to the beginning of a partition */
  37         sector += byte_offset >> log2blksz;
  38         byte_offset &= blk->blksz - 1;
  39
  40         log_debug(" <" LBAFU ", %d, %d>\n", sector, byte_offset, byte_len);
  41
  42         if (byte_offset != 0) {
  43                 int readlen;
  44                 /* read first part which isn't aligned with start of sector */
  45                 if (blk_dread(blk, partition->start + sector, 1,
  46                               (void *)sec_buf) != 1) {
  47                         log_err(" ** %s read error **\n", __func__);
  48                         return 0;
  49                 }
  50                 readlen = min((int)blk->blksz - byte_offset,
  51                               byte_len);
  52                 memcpy(buf, sec_buf + byte_offset, readlen);
  53                 buf += readlen;
  54                 byte_len -= readlen;
  55                 sector++;
  56         }
  57
  58         if (byte_len == 0)
  59                 return 1;
  60
  61         /* read sector aligned part */
  62         block_len = byte_len & ~(blk->blksz - 1);
  63
  64         if (block_len == 0) {
  65                 ALLOC_CACHE_ALIGN_BUFFER(u8, p, blk->blksz);
  66
  67                 block_len = blk->blksz;
  68                 blk_dread(blk, partition->start + sector, 1,
  69                           (void *)p);
  70                 memcpy(buf, p, byte_len);
  71                 return 1;
  72         }
  73
  74         if (blk_dread(blk, partition->start + sector,
  75                       block_len >> log2blksz, (void *)buf) !=
  76                         block_len >> log2blksz) {
  77                 log_err(" ** %s read error - block\n", __func__);
  78                 return 0;
  79         }
  80         block_len = byte_len & ~(blk->blksz - 1);
  81         buf += block_len;
  82         byte_len -= block_len;
  83         sector += block_len / blk->blksz;
  84
  85         if (byte_len != 0) {
  86                 /* read rest of data which are not in whole sector */
  87                 if (blk_dread(blk, partition->start + sector, 1,
  88                               (void *)sec_buf) != 1) {
  89                         log_err("* %s read error - last part\n", __func__);
  90                         return 0;
  91                 }
  92                 memcpy(buf, sec_buf, byte_len);
  93         }
  94         return 1;
  95 }