[PATCH v2 02/11] block: sed-opal: unify space check in add_token_*

[Jonas Rabenstein]

All add_token_* functions have a common set of conditions that have to
be checked. Use a common function for those checks in order to avoid
different behaviour as well as code duplication.

Signed-off-by: Jonas Rabenstein <jonas.rabenst...@studium.uni-erlangen.de>

diff --git a/block/sed-opal.c b/block/sed-opal.c
index 5aa41744b8f1..771b4cfff95c 100644
--- a/block/sed-opal.c
+++ b/block/sed-opal.c
@@ -510,15 +510,24 @@ static int opal_discovery0(struct opal_dev *dev, void 
*data)
        return opal_discovery0_end(dev);
 }
 
-static void add_token_u8(int *err, struct opal_dev *cmd, u8 tok)
+static bool can_add(int *err, struct opal_dev *cmd, size_t len)
 {
        if (*err)
-               return;
-       if (cmd->pos >= IO_BUFFER_LENGTH - 1) {
-               pr_debug("Error adding u8: end of buffer.\n");
+               return false;
+
+       if (len > IO_BUFFER_LENGTH || cmd->pos >= IO_BUFFER_LENGTH - len) {
+               pr_debug("Error adding %zu bytes: end of buffer.\n", len);
                *err = -ERANGE;
-               return;
+               return false;
        }
+
+       return true;
+}
+
+static void add_token_u8(int *err, struct opal_dev *cmd, u8 tok)
+{
+       if (!can_add(err, cmd, 1))
+               return;
        cmd->cmd[cmd->pos++] = tok;
 }
 
@@ -563,9 +572,8 @@ static void add_token_u64(int *err, struct opal_dev *cmd, 
u64 number)
        msb = fls64(number);
        len = DIV_ROUND_UP(msb, 8);
 
-       if (cmd->pos >= IO_BUFFER_LENGTH - len - 1) {
+       if (!can_add(err, cmd, len + 1)) {
                pr_debug("Error adding u64: end of buffer.\n");
-               *err = -ERANGE;
                return;
        }
        add_short_atom_header(cmd, false, false, len);
@@ -587,9 +595,8 @@ static void add_token_bytestring(int *err, struct opal_dev 
*cmd,
                is_short_atom = false;
        }
 
-       if (len >= IO_BUFFER_LENGTH - cmd->pos - header_len) {
+       if (!can_add(err, cmd, header_len + len)) {
                pr_debug("Error adding bytestring: end of buffer.\n");
-               *err = -ERANGE;
                return;
        }
 
-- 
2.16.1