[Mesa-dev] [PATCH 3/3] mesa/swrast: Move memory allocation outside the blit loop

[Ian Romanick]

From: Ian Romanick <ian.d.romanick at intel.com>

Assume the maximum pixel size (16 bytes per pixel).  In addition to
moving redundant malloc and free calls outside the loop, this fixes a
potential resource leak when a surface is mapped and the malloc fails.
This also makes blit_nearest look a bit more like blit_linear.

Signed-off-by: Ian Romanick <ian.d.romanick at intel.com>
---
 src/mesa/swrast/s_blit.c | 45 +++++++++++++++++++++------------------------
 1 file changed, 21 insertions(+), 24 deletions(-)

diff --git a/src/mesa/swrast/s_blit.c b/src/mesa/swrast/s_blit.c
index ecec734..3824162 100644
--- a/src/mesa/swrast/s_blit.c
+++ b/src/mesa/swrast/s_blit.c
@@ -136,7 +136,7 @@ blit_nearest(struct gl_context *ctx,
       UNPACK_Z_INT,
       UNPACK_S,
    } mode = DIRECT;
-   GLubyte *srcMap, *dstMap;
+   GLubyte *srcMap = NULL, *dstMap = NULL;
    GLint srcRowStride, dstRowStride;
    GLint dstRow;
 
@@ -188,6 +188,12 @@ blit_nearest(struct gl_context *ctx,
       return;
    }
 
+   /* allocate the src/dst row buffers */
+   srcBuffer = malloc(16 * srcWidth);
+   dstBuffer = malloc(16 * dstWidth);
+   if (!srcBuffer || !dstBuffer)
+      goto fail_no_memory;
+
    /* Blit to all the draw buffers */
    for (i = 0; i < numDrawBuffers; i++) {
       if (buffer == GL_COLOR_BUFFER_BIT) {
@@ -229,7 +235,7 @@ blit_nearest(struct gl_context *ctx,
       default:
          _mesa_problem(ctx, "unexpected pixel size (%d) in blit_nearest",
                        pixelSize);
-         return;
+         goto fail;
       }
 
       if ((readRb == drawRb) ||
@@ -248,8 +254,7 @@ blit_nearest(struct gl_context *ctx,
                                      GL_MAP_READ_BIT | GL_MAP_WRITE_BIT,
                                      &map, &rowStride);
          if (!map) {
-            _mesa_error(ctx, GL_OUT_OF_MEMORY, "glBlitFramebuffer");
-            return;
+            goto fail_no_memory;
          }
 
          srcMap = map + srcYpos * rowStride + srcXpos * formatSize;
@@ -276,8 +281,7 @@ blit_nearest(struct gl_context *ctx,
                                      srcWidth, srcHeight,
                                      GL_MAP_READ_BIT, &srcMap, &srcRowStride);
          if (!srcMap) {
-            _mesa_error(ctx, GL_OUT_OF_MEMORY, "glBlitFramebuffer");
-            return;
+            goto fail_no_memory;
          }
          ctx->Driver.MapRenderbuffer(ctx, drawRb,
                                      dstXpos, dstYpos,
@@ -285,24 +289,10 @@ blit_nearest(struct gl_context *ctx,
                                      GL_MAP_WRITE_BIT, &dstMap, &dstRowStride);
          if (!dstMap) {
             ctx->Driver.UnmapRenderbuffer(ctx, readRb);
-            _mesa_error(ctx, GL_OUT_OF_MEMORY, "glBlitFramebuffer");
-            return;
+            goto fail_no_memory;
          }
       }
 
-      /* allocate the src/dst row buffers */
-      srcBuffer = malloc(pixelSize * srcWidth);
-      if (!srcBuffer) {
-         _mesa_error(ctx, GL_OUT_OF_MEMORY, "glBlitFrameBufferEXT");
-         return;
-      }
-      dstBuffer = malloc(pixelSize * dstWidth);
-      if (!dstBuffer) {
-         free(srcBuffer);
-         _mesa_error(ctx, GL_OUT_OF_MEMORY, "glBlitFrameBufferEXT");
-         return;
-      }
-
       for (dstRow = 0; dstRow < dstHeight; dstRow++) {
          GLfloat srcRowF = (dstRow + 0.5F) / dstHeight * srcHeight - 0.5F;
          GLint srcRow = IROUND(srcRowF);
@@ -369,14 +359,21 @@ blit_nearest(struct gl_context *ctx,
          }
       }
 
-      free(srcBuffer);
-      free(dstBuffer);
-
       ctx->Driver.UnmapRenderbuffer(ctx, readRb);
       if (drawRb != readRb) {
          ctx->Driver.UnmapRenderbuffer(ctx, drawRb);
       }
    }
+
+fail:
+   free(srcBuffer);
+   free(dstBuffer);
+   return;
+
+fail_no_memory:
+   free(srcBuffer);
+   free(dstBuffer);
+   _mesa_error(ctx, GL_OUT_OF_MEMORY, "glBlitFrameBuffer");
 }
 
 
-- 
1.8.1.4