Enhance download function with Qualcomm HEAD fallback

Author: cccclai

backends/qualcomm/scripts/download_qnn_sdk.py

@@ -117,35 +117,58 @@ def _atomic_download(url: str, dest: pathlib.Path):
 
 
 def _download_archive(url: str, archive_path: pathlib.Path) -> bool:
-    """Reliable download with resume + retries."""
+    """Reliable download with resume + retries + Qualcomm HEAD fallback."""
 
     logger.info("Downloading with resume support: %s", url)
 
     CHUNK_SIZE = 1024 * 1024   # 1MB
-    MAX_RETRIES = 5
-
-    # Determine existing partial file size
     downloaded = archive_path.stat().st_size if archive_path.exists() else 0
-
-    # Get total size
-    head = requests.head(url)
-    if "content-length" not in head.headers:
-        logger.error("Server did not return content-length header!")
+    MAX_RETRIES = 10
+
+    # ---- STEP 1: Try HEAD (may fail for Qualcomm) ----
+    head = requests.head(url, allow_redirects=True)
+
+    def head_looks_invalid(h: requests.Response) -> bool:
+        """Qualcomm sometimes sends HTML wrappers."""
+        if "content-length" not in h.headers:
+            return True
+        size = int(h.headers["content-length"])
+        if size < 1024 * 1024:  # <1MB means HTML stub, not the zip
+            return True
+        ctype = h.headers.get("content-type", "").lower()
+        if "zip" not in ctype:
+            return True
         return False
-    total = int(head.headers["content-length"])
 
-    if downloaded == total:
+    # ---- STEP 2: Fallback: Issue a GET request to discover real size ----
+    if head_looks_invalid(head):
+        logger.warning("HEAD invalid (size=%s, type=%s). Using GET for size detection.",
+                       head.headers.get("content-length"),
+                       head.headers.get("content-type"))
+
+        with requests.get(url, stream=True, allow_redirects=True) as r:
+            r.raise_for_status()
+            if "content-length" not in r.headers:
+                logger.error("Server did not return content-length even on GET!")
+                return False
+            total = int(r.headers["content-length"])
+    else:
+        total = int(head.headers["content-length"])
+
+    logger.info("File size detected: %d bytes", total)
+
+    # ---- Already downloaded? ----
+    if downloaded == total and total > 0:
         logger.info("File already fully downloaded.")
         return True
 
     logger.info("Resuming from %d / %d bytes", downloaded, total)
 
-    # Open file in append mode
+    # ---- STEP 3: Streaming download with HTTP Range ----
     with open(archive_path, "ab") as f:
-
         while downloaded < total:
-            headers = {"Range": f"bytes={downloaded}-"}
 
+            headers = {"Range": f"bytes={downloaded}-"}
             try:
                 with requests.get(url, headers=headers, stream=True) as r:
                     r.raise_for_status()
@@ -160,20 +183,17 @@ def _download_archive(url: str, archive_path: pathlib.Path) -> bool:
                     requests.exceptions.ReadTimeout,
                     urllib3.exceptions.IncompleteRead) as e:
 
-                logger.warning(
-                    "Connection drop during download at %d / %d bytes. Retrying... (%s)",
-                    downloaded, total, e,
-                )
+                logger.warning("Connection drop at %d bytes, retrying... (%s)",
+                               downloaded, e)
                 time.sleep(1)
-                continue  # retry with updated downloaded value
+                continue  # resume from updated offset
 
-            # End of successful pass
             break
 
-    # Validate final size
-    actual = archive_path.stat().st_size
-    if actual != total:
-        logger.error("Download incomplete: expected %d, got %d", total, actual)
+    # ---- Final size check ----
+    final_size = archive_path.stat().st_size
+    if final_size != total:
+        logger.error("Download incomplete: expected %d, got %d", total, final_size)
         return False
 
     logger.info("Download completed successfully.")