From 088862171f8fbd4583f744ca5cbc723aef31ee90 Mon Sep 17 00:00:00 2001
From: Lucjan Bryndza <lucjan.bryndza@mudita.com>
Date: Mon, 14 Dec 2020 09:13:21 +0100
Subject: [PATCH] Fix read and write number of bytes returned

read/write syscalls may read/write less bytes then
requied in the size, so on the larger block size
lfs fuse library fails because read/write returns
less bytes than required.
---
 lfs_fuse_bd.c | 47 +++++++++++++++++++++++++++++++----------------
 1 file changed, 31 insertions(+), 16 deletions(-)

diff --git a/lfs_fuse_bd.c b/lfs_fuse_bd.c
index 9859c32..e759f14 100644
--- a/lfs_fuse_bd.c
+++ b/lfs_fuse_bd.c
@@ -71,17 +71,24 @@ int lfs_fuse_bd_read(const struct lfs_config *cfg, lfs_block_t block,
     assert(block < cfg->block_count);
 
     // go to block
-    off_t err = lseek(fd, (off_t)block*cfg->block_size + (off_t)off, SEEK_SET);
+    off_t offrq = (off_t)block*cfg->block_size + (off_t)off;
+    off_t err = lseek(fd,offrq, SEEK_SET);
     if (err < 0) {
         return -errno;
+    } else if( err != offrq ) {
+        return LFS_ERR_IO;
     }
-
-    // read block
-    ssize_t res = read(fd, buffer, (size_t)size);
-    if (res < 0) {
-        return -errno;
-    }
-
+    char* rdb = buffer;
+    do {
+        // read block
+        ssize_t res = read(fd, rdb, (size_t)size);
+        if (res <= 0) {
+            return (res==0)?(LFS_ERR_IO):(-errno);
+        } else {
+            rdb += res;
+            size -= res;
+        }
+    } while( size > 0 );
     return 0;
 }
 
@@ -93,16 +100,25 @@ int lfs_fuse_bd_prog(const struct lfs_config *cfg, lfs_block_t block,
     assert(block < cfg->block_count);
 
     // go to block
-    off_t err = lseek(fd, (off_t)block*cfg->block_size + (off_t)off, SEEK_SET);
+    off_t offrq = (off_t)block*cfg->block_size + (off_t)off;
+    off_t err = lseek(fd,offrq, SEEK_SET);
     if (err < 0) {
         return -errno;
+    } else if(err != offrq )
+    {
+        return LFS_ERR_IO;
     }
-
-    // write block
-    ssize_t res = write(fd, buffer, (size_t)size);
-    if (res < 0) {
-        return -errno;
-    }
+    const char* wrb = buffer;
+    do {
+        // write block
+        ssize_t res = write(fd, wrb, (size_t)size);
+        if (res <= 0) {
+            return (res==0)?(LFS_ERR_IO):(-errno);
+        } else {
+            wrb += res;
+            size -= res;
+        }
+    } while(0);
 
     return 0;
 }
@@ -119,7 +135,6 @@ int lfs_fuse_bd_sync(const struct lfs_config *cfg) {
     if (err) {
         return -errno;
     }
-
     return 0;
 }