fix: several bug fixes related to internal use of image_span (AcademySoftwareFoundation#5004)

lgritz · web-flow · commit f862c0688ac1 · 2026-01-18T09:24:10.000-08:00
* ImageBuf internal buffer span lacked correct chansize. The internal
`m_bufspan` is an `image_span&lt;byte&gt;`, and as such, it needs to remember
the size of the original data type. Otherwise, there's a cascade of
potential errors when it thinks that the individual values are byte
sized.

* In both ImageInput and ImageOutput, several sanity checks of
image_span size versus expectations were incorrect. They were only
checking if the total byte sizes matched expectations, but they are
allowed to disagree when you consider type conversions (in which case,
it's the total number of values that need to match, not the total byte
sizes.

Signed-off-by: Larry Gritz &lt;lg@larrygritz.com&gt;
diff --git a/src/libOpenImageIO/imagebuf.cpp b/src/libOpenImageIO/imagebuf.cpp
@@ -150,10 +150,11 @@ class ImageBufImpl {
                      stride_t ystride = AutoStride,
                      stride_t zstride = AutoStride)
     {
-        m_bufspan = image_span(reinterpret_cast<std::byte*>(data),
-                               m_spec.nchannels, m_spec.width, m_spec.height,
-                               m_spec.depth, m_spec.format.size(), xstride,
-                               ystride, zstride);
+        auto formatsize = m_spec.format.size();
+        m_bufspan       = image_span(reinterpret_cast<std::byte*>(data),
+                                     m_spec.nchannels, m_spec.width, m_spec.height,
+                                     m_spec.depth, formatsize, xstride, ystride,
+                                     zstride, formatsize);
     }
 
     bool init_spec(string_view filename, int subimage, int miplevel,
diff --git a/src/libOpenImageIO/imageinput.cpp b/src/libOpenImageIO/imageinput.cpp
@@ -211,6 +211,40 @@ ImageInput::spec_dimensions(int subimage, int miplevel)
 
 
 
+// Utility: Make sure the provided data span is the right size for the
+// image described by spec and datatype. If they don't match, issue an
+// error and return false.
+static bool
+check_span_size(ImageInput* in, string_view caller, const ImageSpec& spec,
+                TypeDesc datatype, imagesize_t npixels, int chbegin, int chend,
+                const image_span<std::byte>& data)
+{
+    // One of two things must be correct: Either format is Unknown and the
+    // total byte size needs to match the "native" size, or the format is
+    // concrete and the number of value must match (it's ok if the size
+    // doesn't match, since a data type conversion will occur).
+    if (datatype.is_unknown()) {  // Unknown assumes native chan types
+        size_t sz = npixels * spec.pixel_bytes(chbegin, chend, true);
+        if (sz != data.size_bytes()) {
+            in->errorfmt(
+                "{}: image_span size is incorrect ({} bytes vs {} needed)",
+                caller, data.size_bytes(), sz);
+            return false;
+        }
+    } else {  // single concrete type
+        size_t nvals = npixels * size_t(chend - chbegin);
+        if (nvals != data.nvalues()) {
+            in->errorfmt(
+                "{}: image_span size is incorrect ({} values vs {} needed)",
+                caller, data.nvalues(), nvals);
+            return false;
+        }
+    }
+    return true;
+}
+
+
+
 bool
 ImageInput::read_scanline(int y, int z, TypeDesc format, void* data,
                           stride_t xstride)
@@ -300,16 +334,10 @@ ImageInput::read_scanlines(int subimage, int miplevel, int ybegin, int yend,
                  chend);
         return false;
     }
-    size_t isize = (format == TypeUnknown
-                        ? spec.pixel_bytes(chbegin, chend, true /*native*/)
-                        : format.size() * (chend - chbegin))
-                   * size_t(spec.width);
-    if (isize != data.size_bytes()) {
-        errorfmt(
-            "read_scanlines: Buffer size is incorrect ({} bytes vs {} needed)",
-            isize, data.size_bytes());
+    if (!check_span_size(this, "read_scanlines", m_spec, format,
+                         m_spec.width * size_t(yend - ybegin), chbegin, chend,
+                         data))
         return false;
-    }
 
     // Default implementation (for now): call the old pointer+stride
     return read_scanlines(subimage, miplevel, ybegin, yend, 0, chbegin, chend,
@@ -656,16 +684,11 @@ ImageInput::read_tiles(int subimage, int miplevel, int xbegin, int xend,
         errorfmt("read_tiles: invalid channel range [{},{})", chbegin, chend);
         return false;
     }
-    size_t isize = (format == TypeUnknown
-                        ? spec.pixel_bytes(chbegin, chend, true /*native*/)
-                        : format.size() * (chend - chbegin))
-                   * size_t(xend - xbegin) * size_t(yend - ybegin)
-                   * size_t(zend - zbegin);
-    if (isize != data.size_bytes()) {
-        errorfmt("read_tiles: Buffer size is incorrect ({} bytes vs {} needed)",
-                 isize, data.size_bytes());
+    if (!check_span_size(this, "read_tiles", m_spec, format,
+                         size_t(xend - xbegin) * size_t(yend - ybegin)
+                             * size_t(zend - zbegin),
+                         chbegin, chend, data))
         return false;
-    }
 
     // Default implementation (for now): call the old pointer+stride
     return read_tiles(subimage, miplevel, ybegin, yend, xbegin, xend, zbegin,
@@ -1164,24 +1187,6 @@ bool
 ImageInput::read_image(int subimage, int miplevel, int chbegin, int chend,
                        TypeDesc format, const image_span<std::byte>& data)
 {
-#if 0
-    ImageSpec spec = spec_dimensions(subimage, miplevel);
-    if (chend < 0 || chend > spec.nchannels)
-        chend = spec.nchannels;
-    size_t isize = (format == TypeUnknown
-                        ? spec.pixel_bytes(chbegin, chend, true /*native*/)
-                        : format.size() * (chend - chbegin))
-                   * spec.image_pixels();
-    if (isize != data.size_bytes()) {
-        errorfmt("read_image: Buffer size is incorrect ({} bytes vs {} needed)",
-                 sz, data.size_bytes());
-        return false;
-    }
-
-    // Default implementation (for now): call the old pointer+stride
-    return read_image(subimage, miplevel, chbegin, chend, format, data.data(),
-                      data.xstride(), data.ystride(), data.zstride());
-#else
     OIIO::pvt::LoggedTimer logtime("II::read_image");
     ImageSpec spec;
     int rps = 0;
@@ -1210,16 +1215,9 @@ ImageInput::read_image(int subimage, int miplevel, int chbegin, int chend,
         errorfmt("read_image: invalid channel range [{},{})", chbegin, chend);
         return false;
     }
-    int nchans         = chend - chbegin;
-    bool native        = (format == TypeUnknown);
-    size_t pixel_bytes = native ? spec.pixel_bytes(chbegin, chend, native)
-                                : (format.size() * nchans);
-    size_t isize       = pixel_bytes * spec.image_pixels();
-    if (isize != data.size_bytes()) {
-        errorfmt("read_image: Buffer size is incorrect ({} bytes vs {} needed)",
-                 isize, data.size_bytes());
+    if (!check_span_size(this, "read_image", m_spec, format,
+                         spec.image_pixels(), chbegin, chend, data))
         return false;
-    }
 
     bool ok = true;
     if (spec.tile_width) {  // Tiled image -- rely on read_tiles
@@ -1259,7 +1257,6 @@ ImageInput::read_image(int subimage, int miplevel, int chbegin, int chend,
         }
     }
     return ok;
-#endif
 }
 
 
diff --git a/src/libOpenImageIO/imageoutput.cpp b/src/libOpenImageIO/imageoutput.cpp
@@ -102,6 +102,40 @@ ImageOutput::~ImageOutput()
 
 
 
+// Utility: Make sure the provided data span is the right size for the
+// image described by spec and datatype. If they don't match, issue an
+// error and return false.
+static bool
+check_span_size(ImageOutput* out, string_view caller, const ImageSpec& spec,
+                TypeDesc datatype, imagesize_t npixels,
+                const image_span<const std::byte>& data)
+{
+    // One of two things must be correct: Either format is Unknown and the
+    // total byte size needs to match the "native" size, or the format is
+    // concrete and the number of value must match (it's ok if the size
+    // doesn't match, since a data type conversion will occur).
+    if (datatype.is_unknown()) {  // Unknown assumes native chan types
+        size_t sz = npixels * spec.pixel_bytes(true);
+        if (sz != data.size_bytes()) {
+            out->errorfmt(
+                "{}: image_span size is incorrect ({} bytes vs {} needed)",
+                caller, data.size_bytes(), sz);
+            return false;
+        }
+    } else {  // single concrete type
+        size_t nvals = npixels * size_t(spec.nchannels);
+        if (nvals != data.nvalues()) {
+            out->errorfmt(
+                "{}: image_span size is incorrect ({} values vs {} needed)",
+                caller, data.nvalues(), nvals);
+            return false;
+        }
+    }
+    return true;
+}
+
+
+
 bool
 ImageOutput::write_scanline(int /*y*/, int /*z*/, TypeDesc /*format*/,
                             const void* /*data*/, stride_t /*xstride*/)
@@ -120,13 +154,9 @@ ImageOutput::write_scanline(int y, TypeDesc format,
         errorfmt("write_scanlines: Invalid scanline index {}", y);
         return false;
     }
-    size_t sz = m_spec.scanline_bytes(format);
-    if (sz != data.size_bytes()) {
-        errorfmt(
-            "write_scanline: Buffer size is incorrect ({} bytes vs {} needed)",
-            sz, data.size_bytes());
+    if (!check_span_size(this, "write_scanline", m_spec, format, m_spec.width,
+                         data))
         return false;
-    }
 
     // Default implementation (for now): call the old pointer+stride
     return write_scanline(y, 0, format, data.data(), data.xstride());
@@ -164,13 +194,9 @@ ImageOutput::write_scanlines(int ybegin, int yend, TypeDesc format,
         errorfmt("write_scanlines: Invalid scanline range {}-{}", ybegin, yend);
         return false;
     }
-    size_t sz = m_spec.scanline_bytes(format) * size_t(yend - ybegin);
-    if (sz != data.size_bytes()) {
-        errorfmt(
-            "write_scanlines: Buffer size is incorrect ({} bytes vs {} needed)",
-            sz, data.size_bytes());
+    if (!check_span_size(this, "write_scanlines", m_spec, format,
+                         m_spec.width * size_t(yend - ybegin), data))
         return false;
-    }
 
     // Default implementation (for now): call the old pointer+stride
     return write_scanlines(ybegin, yend, 0, format, data.data(), data.xstride(),
@@ -194,15 +220,9 @@ bool
 ImageOutput::write_tile(int x, int y, int z, TypeDesc format,
                         const image_span<const std::byte>& data)
 {
-    size_t sz = format == TypeUnknown
-                    ? m_spec.pixel_bytes(true /*native*/)
-                    : m_spec.tile_pixels() * size_t(m_spec.nchannels)
-                          * format.size();
-    if (sz != data.size_bytes()) {
-        errorfmt("write_tile: Buffer size is incorrect ({} bytes vs {} needed)",
-                 sz, data.size_bytes());
+    if (!check_span_size(this, "write_tile", m_spec, format,
+                         m_spec.tile_pixels(), data))
         return false;
-    }
 
     // Default implementation (for now): call the old pointer+stride
     return write_tile(x, y, z, format, data.data(), data.xstride(),
@@ -691,12 +711,9 @@ bool
 ImageOutput::write_image(TypeDesc format,
                          const image_span<const std::byte>& data)
 {
-    size_t sz = m_spec.image_bytes(/*native=*/format == TypeUnknown);
-    if (sz != data.size_bytes()) {
-        errorfmt("write_image: Buffer size is incorrect ({} bytes vs {} needed)",
-                 sz, data.size_bytes());
+    if (!check_span_size(this, "write_image", m_spec, format,
+                         m_spec.image_pixels(), data))
         return false;
-    }
 
     // Default implementation (for now): call the old pointer+stride
     return write_image(format, data.data(), data.xstride(), data.ystride(),
