Merge branch 'main' into gh-150449-fix-sqlite-blob-negative-step-slice

Resolve the conflict in ass_subscript_slice(): keep the region computation which handles negative and extreme steps, and read it into a plain buffer as in gh-155702, instead of patching the bytes object read from the blob.
serhiy-storchaka · Aug 14, 2026 · May 26, 2026 · May 26, 2026 · May 26, 2026 · May 26, 2026
commit c587f21bb459f7690ff7d93108679601388feb97
@@ -571,24 +571,31 @@ ass_subscript_slice(pysqlite_Blob *self, PyObject *item, PyObject *value)
         rc = inner_write(self, vbuf.buf, len, start);
     }
     else {
-        // Compute the contiguous blob region covering all slice elements, then
-        // update each element using the standard size_t-cursor pattern that
-        // handles both positive and negative steps via unsigned arithmetic.
+        /* Compute the contiguous blob region covering all slice elements,
+           read it, patch each element and write it back.  The object
+           returned by read_multiple() cannot be used as the buffer, because
+           for a single byte it is an immortal singleton. */
         Py_ssize_t last = start + (len - 1) * step;
         Py_ssize_t write_offset = Py_MIN(start, last);
         Py_ssize_t write_length = Py_ABS(start - last) + 1;
-        PyObject *blob_bytes = read_multiple(self, write_length, write_offset);
-        if (blob_bytes != NULL) {
-            char *blob_buf = PyBytes_AS_STRING(blob_bytes);
-            size_t cur;
-            Py_ssize_t i;
-            for (cur = (size_t)start, i = 0; i < len;
-                 cur += (size_t)step, i++) {
-                blob_buf[(Py_ssize_t)cur - write_offset] =
-                    ((char *)vbuf.buf)[i];
+        char *buf = PyMem_Malloc(write_length);
+        if (buf == NULL) {
+            PyErr_NoMemory();
+        }
+        else {
+            if (inner_read(self, buf, write_length, write_offset) == 0) {
+                /* The size_t cursor handles both positive and negative steps
+                   via unsigned arithmetic. */
+                size_t cur;
+                Py_ssize_t i;
+                for (cur = (size_t)start, i = 0; i < len;
+                     cur += (size_t)step, i++) {
+                    buf[(Py_ssize_t)cur - write_offset] =
+                        ((char *)vbuf.buf)[i];
+                }
+                rc = inner_write(self, buf, write_length, write_offset);
             }
-            rc = inner_write(self, blob_buf, write_length, write_offset);
-            Py_DECREF(blob_bytes);
+            PyMem_Free(buf);
         }
     }
     PyBuffer_Release(&vbuf);