[Mesa-dev] [PATCH 6/7] mesa: rework the meaning of gl_debug_message::length

[Emil Velikov]

Currently it stores strlen(buf) whenever the user originally provided a
negative value for length.

Although I've not seen any explicit text in the spec, CTS requires that
the very same length (be that negative value or not) is returned back on
Pop.

So let's push down the length < 0 checks, tweak the meaning of
gl_debug_message::length and fix GetDebugMessageLog to add and count the
null terminators, as required by the spec.

XXX:
 - should we use -1, or strlen on ENOMEM in debug_message_store ?
 - should we return the original lengths, strlen or strlen+1 in
GetDebugMessageLog lengths ?
 - split out the GetDebugMessageLog fixes into separate patch ?
 - split the "push the length < 0 check further down" into separate
patch ?

Signed-off-by: Emil Velikov <emil.l.velikov at gmail.com>
---
 src/mesa/main/errors.c | 43 ++++++++++++++++++++++++-------------------
 1 file changed, 24 insertions(+), 19 deletions(-)

diff --git a/src/mesa/main/errors.c b/src/mesa/main/errors.c
index dd9b800..b10c421 100644
--- a/src/mesa/main/errors.c
+++ b/src/mesa/main/errors.c
@@ -76,6 +76,8 @@ struct gl_debug_message
    enum mesa_debug_type type;
    GLuint id;
    enum mesa_debug_severity severity;
+   /* length as given by the user - if message was explicitly null terminated,
+    * length can be negative */
    GLsizei length;
    GLcharARB *message;
 };
@@ -211,14 +213,19 @@ debug_message_store(struct gl_debug_message *msg,
                     enum mesa_debug_severity severity,
                     GLsizei len, const char *buf)
 {
+   GLsizei length = len;
+
    assert(!msg->message && !msg->length);
 
-   msg->message = malloc(len+1);
+   if (length < 0)
+      length = strlen(buf);
+
+   msg->message = malloc(length+1);
    if (msg->message) {
-      (void) strncpy(msg->message, buf, (size_t)len);
-      msg->message[len] = '\0';
+      (void) strncpy(msg->message, buf, (size_t)length);
+      msg->message[length] = '\0';
 
-      msg->length = len+1;
+      msg->length = len;
       msg->source = source;
       msg->type = type;
       msg->id = id;
@@ -229,7 +236,7 @@ debug_message_store(struct gl_debug_message *msg,
 
       /* malloc failed! */
       msg->message = out_of_memory;
-      msg->length = strlen(out_of_memory)+1;
+      msg->length = -1;
       msg->source = MESA_DEBUG_SOURCE_OTHER;
       msg->type = MESA_DEBUG_TYPE_ERROR;
       msg->id = oom_msg_id;
@@ -608,7 +615,7 @@ debug_log_message(struct gl_debug_state *debug,
    GLint nextEmpty;
    struct gl_debug_message *emptySlot;
 
-   assert(len >= 0 && len < MAX_DEBUG_MESSAGE_LENGTH);
+   assert(len < MAX_DEBUG_MESSAGE_LENGTH);
 
    if (log->NumMessages == MAX_DEBUG_LOGGED_MESSAGES)
       return;
@@ -991,8 +998,6 @@ _mesa_DebugMessageInsert(GLenum source, GLenum type, GLuint id,
    if (!validate_params(ctx, INSERT, callerstr, source, type, severity))
       return; /* GL_INVALID_ENUM */
 
-   if (length < 0)
-      length = strlen(buf);
    if (!validate_length(ctx, callerstr, length))
       return; /* GL_INVALID_VALUE */
 
@@ -1034,23 +1039,28 @@ _mesa_GetDebugMessageLog(GLuint count, GLsizei logSize, GLenum *sources,
 
    for (ret = 0; ret < count; ret++) {
       const struct gl_debug_message *msg = debug_fetch_message(debug);
+      GLsizei len;
 
       if (!msg)
          break;
 
-      if (logSize < msg->length && messageLog != NULL)
+      len = msg->length;
+      if (len < 0)
+         len = strlen(msg->message);
+
+      if (logSize < len+1 && messageLog != NULL)
          break;
 
       if (messageLog) {
-         assert(msg->message[msg->length-1] == '\0');
-         (void) strncpy(messageLog, msg->message, (size_t)msg->length);
+         assert(msg->message[len] == '\0');
+         (void) strncpy(messageLog, msg->message, (size_t)len+1);
 
-         messageLog += msg->length;
-         logSize -= msg->length;
+         messageLog += len+1;
+         logSize -= len+1;
       }
 
       if (lengths)
-         *lengths++ = msg->length;
+         *lengths++ = msg->length; // XXX: or len or len+1 ?
       if (severities)
          *severities++ = debug_severity_enums[msg->severity];
       if (sources)
@@ -1160,8 +1170,6 @@ _mesa_PushDebugGroup(GLenum source, GLuint id, GLsizei length,
       return;
    }
 
-   if (length < 0)
-      length = strlen(message);
    if (!validate_length(ctx, callerstr, length))
       return; /* GL_INVALID_VALUE */
 
@@ -1613,9 +1621,6 @@ _mesa_shader_debug( struct gl_context *ctx, GLenum type, GLuint *id,
 
    debug_get_id(id);
 
-   if (len < 0)
-      len = strlen(msg);
-
    /* Truncate the message if necessary. */
    if (len >= MAX_DEBUG_MESSAGE_LENGTH)
       len = MAX_DEBUG_MESSAGE_LENGTH - 1;
-- 
2.6.2