Fix oversize writes to write to correct area of disk

[nbd.git] / nbd-server.c

diff --git a/nbd-server.c b/nbd-server.c
index a99c27b..41b847a 100644 (file)
--- a/nbd-server.c
+++ b/nbd-server.c
@@ -261,6 +261,12 @@ typedef struct {
                                  is PARAM_BOOL. */
 } PARAM;
 
+/**
+ * Translate a command name into human readable form
+ *
+ * @param command The command number (after applying NBD_CMD_MASK_COMMAND)
+ * @return pointer to the command name
+ **/
 static inline const char * getcommandname(uint64_t command) {
        switch (command) {
        case NBD_CMD_READ:
@@ -354,6 +360,24 @@ static inline void readit(int f, void *buf, size_t len) {
 }
 
 /**
+ * Consume data from an FD that we don't want
+ *
+ * @param f a file descriptor
+ * @param buf a buffer
+ * @param len the number of bytes to consume
+ * @param bufsiz the size of the buffer
+ **/
+static inline void consume(int f, void * buf, size_t len, size_t bufsiz) {
+       size_t curlen;
+       while (len>0) {
+               curlen = (len>bufsiz)?bufsiz:len;
+               readit(f, buf, curlen);
+               len -= curlen;
+       }
+}
+
+
+/**
  * Write data from a buffer into a filedescriptor
  *
  * @param f a file descriptor
@@ -1077,6 +1101,7 @@ void myseek(int handle,off_t a) {
  * @param buf The buffer to write from
  * @param len The length of buf
  * @param client The client we're serving for
+ * @param fua Flag to indicate 'Force Unit Access'
  * @return The number of bytes actually written, or -1 in case of an error
  **/
 ssize_t rawexpwrite(off_t a, char *buf, size_t len, CLIENT *client, int fua) {
@@ -1141,6 +1166,12 @@ ssize_t rawexpwrite(off_t a, char *buf, size_t len, CLIENT *client, int fua) {
 
 /**
  * Call rawexpwrite repeatedly until all data has been written.
+ *
+ * @param a The offset where the write should start
+ * @param buf The buffer to write from
+ * @param len The length of buf
+ * @param client The client we're serving for
+ * @param fua Flag to indicate 'Force Unit Access'
  * @return 0 on success, nonzero on failure
  **/
 int rawexpwrite_fully(off_t a, char *buf, size_t len, CLIENT *client, int fua) {
@@ -1245,6 +1276,7 @@ int expread(off_t a, char *buf, size_t len, CLIENT *client) {
  * @param buf The buffer to write from
  * @param len The length of buf
  * @param client The client we're going to write for.
+ * @param fua Flag to indicate 'Force Unit Access'
  * @return 0 on success, nonzero on failure
  **/
 int expwrite(off_t a, char *buf, size_t len, CLIENT *client, int fua) {
@@ -1299,6 +1331,12 @@ int expwrite(off_t a, char *buf, size_t len, CLIENT *client, int fua) {
        return 0;
 }
 
+/**
+ * Flush data to a client
+ *
+ * @param client The client we're going to write for.
+ * @return 0 on success, nonzero on failure
+ **/
 int expflush(CLIENT *client) {
        gint i;
 
@@ -1527,18 +1565,21 @@ int mainloop(CLIENT *client) {
                                    (client->server->flags & F_AUTOREADONLY)) {
                                        DEBUG("[WRITE to READONLY!]");
                                        ERROR(client, reply, EPERM);
+                                       consume(client->net, buf, len-currlen, BUFSIZE);
                                        continue;
                                }
-                               if (expwrite(request.from, buf, len, client,
+                               if (expwrite(request.from, buf, currlen, client,
                                             request.type & NBD_CMD_FLAG_FUA)) {
                                        DEBUG("Write failed: %m" );
                                        ERROR(client, reply, errno);
+                                       consume(client->net, buf, len-currlen, BUFSIZE);
                                        continue;
                                }
-                               SEND(client->net, reply);
                                len -= currlen;
+                               request.from += currlen;
                                currlen = (len < BUFSIZE) ? len : BUFSIZE;
                        }
+                       SEND(client->net, reply);
                        DEBUG("OK!\n");
                        continue;