[Qemu-devel] [PATCH 3/5] atapi: GESN: Spin off No Event Available handling into own function

[Amit Shah <amit.shah@redhat.com>]

Handle GET_EVENT_STATUS_NOTIFICATION's No Event Available status in its
own function.

Also ensure the buffer the driver sent us is big enough to fill in all
the data we have -- else just fill in as much as the buffer can hold.

Signed-off-by: Amit Shah <amit.shah@redhat.com>
---
 hw/ide/core.c |   42 ++++++++++++++++++++++++++++++++++++------
 1 files changed, 36 insertions(+), 6 deletions(-)

diff --git a/hw/ide/core.c b/hw/ide/core.c
index c4a5a13..730587e 100644
--- a/hw/ide/core.c
+++ b/hw/ide/core.c
@@ -1084,14 +1084,45 @@ static int ide_dvd_read_structure(IDEState *s, int format,
     }
 }
 
+static unsigned int event_status_nea(uint8_t *buf, unsigned int max_len)
+{
+    unsigned int used_len;
+
+    /*
+     * Ensure we don't write on memory we don't have.
+     * max_len of 0 should not produce an error as well.
+     */
+    used_len = 0;
+
+    /* No event descriptor returned */
+    if (max_len > 0) {
+        buf[0] = 0;
+        used_len++;
+    }
+    if (max_len > 1) {
+        buf[1] = 0;
+        used_len++;
+    }
+    if (max_len > 2) {
+        buf[2] = 0x80;           /* No Event Available (NEA) */
+        used_len++;
+    }
+    if (max_len > 3) {
+        buf[3] = 0x00;           /* Empty supported event classes */
+        used_len++;
+    }
+    return used_len;
+}
+
 static void handle_get_event_status_notification(IDEState *s,
                                                  uint8_t *buf,
                                                  const uint8_t *packet)
 {
-    unsigned int max_len;
+    unsigned int max_len, used_len;
 
     max_len = ube16_to_cpu(packet + 7);
 
+    /* It is fine by the MMC spec to not support async mode operations */
     if (!(packet[1] & 0x01)) { /* asynchronous mode */
         /* Only polling is supported, asynchronous mode is not. */
         ide_atapi_cmd_error(s, SENSE_ILLEGAL_REQUEST,
@@ -1099,12 +1130,11 @@ static void handle_get_event_status_notification(IDEState *s,
         return;
     }
 
-    /* polling */
+    /* polling mode operation */
+
     /* We don't support any event class (yet). */
-    cpu_to_ube16(buf, 0x00); /* No event descriptor returned */
-    buf[2] = 0x80;           /* No Event Available (NEA) */
-    buf[3] = 0x00;           /* Empty supported event classes */
-    ide_atapi_cmd_reply(s, 4, max_len);
+    used_len = event_status_nea(buf, max_len);
+    ide_atapi_cmd_reply(s, used_len, max_len);
 }
 
 static void ide_atapi_cmd(IDEState *s)
-- 
1.7.4.2