[plugin] OPDS: ignore query string in file extension workaround (#14304)

Closes <https://github.com/koreader/koreader/issues/14300>.

plugins/opds.koplugin/opdsbrowser.lua

@@ -647,16 +647,29 @@ function OPDSBrowser:genItemTableFromCatalog(catalog, item_url)
                         and link.rel ~= "subsection" then
                         -- Check for the presence of the pdf suffix and add it
                         -- if it's missing.
-                        local href = link.href
+                        local original_href = link.href
+                        local parsed = url.parse(original_href)
+                        if not parsed then parsed = { path = original_href } end
+                        local path = parsed.path or ""
                         -- Calibre web OPDS download links end with "/<filetype>/"
-                        if not util.stringEndsWith(href, "/pdf/") then
+                        if not util.stringEndsWith(path, "/pdf/") then
-                            if util.getFileNameSuffix(href) ~= "pdf" then
+                            local appended = false
-                                href = href .. ".pdf"
+                            if util.getFileNameSuffix(path) ~= "pdf" then
+                                if path == "" then
+                                    path = ".pdf"
+                                else
+                                    path = path .. ".pdf"
+                                end
+                                appended = true
+                            end
+                            if appended then
+                                parsed.path = path
+                                local new_href = url.build(parsed)
+                                table.insert(item.acquisitions, {
+                                    type = link.title,
+                                    href = build_href(new_href),
+                                })
                             end
-                            table.insert(item.acquisitions, {
-                                type = link.title,
-                                href = build_href(href),
-                            })
                         end
                     end
                 end

spec/unit/opds_spec.lua

@@ -290,6 +290,22 @@ local facet_sample = [[
 </feed>
 ]]
 
+local pdf_query_sample = [[
+<?xml version="1.0" encoding="utf-8"?>
+<feed xmlns="http://www.w3.org/2005/Atom" xmlns:dc="http://purl.org/dc/terms/" xmlns:os="http://a9.com/-/spec/opensearch/1.1/" xmlns:opds="http://opds-spec.org/2010/catalog">
+    <id>tag:root:pdfquery</id>
+    <title>PDF Query Test</title>
+    <updated>2025-09-11T00:00:00Z</updated>
+    <entry>
+        <title>Sample PDF With Query</title>
+        <id>urn:pdf:with:query</id>
+        <updated>2025-09-11T00:00:00Z</updated>
+        <content type="text">A PDF that already has .pdf before a query parameter.</content>
+        <link href="http://example.org/books/file.pdf?opds" type="application/pdf" title="pdf" rel="related" />
+    </entry>
+</feed>
+]]
+
 describe("OPDS module", function()
     local socketutil
     local OPDSParser, OPDSBrowser
@@ -427,5 +443,23 @@ describe("OPDS module", function()
             assert.truthy(item_table)
             assert.are_not.same(item_table[1].image, "http://flibusta.is/opds/author/75357")
         end)
+
+        it("should not append .pdf after query parameters or duplicate acquisition entries #14300 #internet", function()
+            local catalog = OPDSParser:parse(pdf_query_sample)
+            local item_table = OPDSBrowser:genItemTableFromCatalog(catalog, "http://example.org/opds")
+
+            assert.truthy(item_table)
+            assert.are.same(1, #item_table)
+            local acquisitions = item_table[1].acquisitions
+            assert.truthy(acquisitions)
+            -- Only one acquisition entry should be present (generic provider entry).
+            assert.are.same(1, #acquisitions)
+            local href = acquisitions[1].href
+            assert.truthy(href)
+            -- It must contain the original query parameter unchanged.
+            assert(href:match("file%.pdf%?opds$"))
+            -- And must NOT have an extra .pdf appended after the query string.
+            assert(not href:match("opds%.pdf$"))
+        end)
     end)
 end)