iotests: Add poke_file_[bl]e functions

Similarly to peek_file_[bl]e, we may want to write binary integers into
a file.  Currently, this often means messing around with poke_file and
raw binary strings.  I hope these functions make it a bit more
comfortable.

Signed-off-by: Max Reitz <mreitz@redhat.com>
Code-suggested-by: Eric Blake <eblake@redhat.com>
Message-Id: <20200324172757.1173824-3-mreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>

1 files changed, 24 insertions, 0 deletions

diff --git a/tests/qemu-iotests/common.rc b/tests/qemu-iotests/common.rc
index 4c246c0..bf3b9fd 100644
--- a/tests/qemu-iotests/common.rc
+++ b/tests/qemu-iotests/common.rc
@@ -53,6 +53,30 @@ poke_file()
     printf "$3" | dd "of=$1" bs=1 "seek=$2" conv=notrunc &>/dev/null
 }
 
+# poke_file_le $img_filename $offset $byte_width $value
+# Example: poke_file_le "$TEST_IMG" 512 2 65534
+poke_file_le()
+{
+    local img=$1 ofs=$2 len=$3 val=$4 str=''
+
+    while ((len--)); do
+        str+=$(printf '\\x%02x' $((val & 0xff)))
+        val=$((val >> 8))
+    done
+
+    poke_file "$img" "$ofs" "$str"
+}
+
+# poke_file_be $img_filename $offset $byte_width $value
+# Example: poke_file_be "$TEST_IMG" 512 2 65279
+poke_file_be()
+{
+    local img=$1 ofs=$2 len=$3 val=$4
+    local str=$(printf "%0$((len * 2))x\n" $val | sed 's/\(..\)/\\x\1/g')
+
+    poke_file "$img" "$ofs" "$str"
+}
+
 # peek_file_le 'test.img' 512 2 => 65534
 peek_file_le()
 {