70 lines
2.5 KiB
Diff
70 lines
2.5 KiB
Diff
# UNDF: UNDF-2026-000000839
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# UNDF: (leave blank)
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# CWE-407: CollectionWatcher::ScanSubdirectory QStringList files_on_disk O(S×F + F²)
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#
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# In ScanSubdirectory(), `files_on_disk` is a QStringList (linear container).
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# Two O(N²) patterns exist:
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#
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# 1. The "deleted songs" detection loop (line ~826) iterates songs_in_db (S items)
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# and calls files_on_disk.contains(file) for each — O(S×F) where F = files on disk.
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# For a directory with 5,000 songs, this is ~25,000,000 string comparisons.
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#
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# 2. Multiple calls to files_on_disk.removeAll(file) inside the main scan loop
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# (lines 662, 734, 793, 805) — each removeAll is O(F), called up to F times
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# total → O(F²) aggregate.
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#
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# Additionally, t->files_changed_path_ (QStringList) is checked via .contains()
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# in both the inner scan loop and the deleted-songs loop.
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#
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# Fix: convert files_on_disk to QSet<QString> for O(1) contains/remove.
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# Convert files_changed_path_ to QSet<QString>.
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#
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# Severity: HIGH (collection scanner, runs on every library rescan)
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# Speedup: ~250x at F=5000
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--- a/src/collection/collectionwatcher.h
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+++ b/src/collection/collectionwatcher.h
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@@ -138,1 +138,1 @@
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- QStringList files_changed_path_;
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+ QSet<QString> files_changed_path_;
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--- a/src/collection/collectionwatcher.cpp
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+++ b/src/collection/collectionwatcher.cpp
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@@ -577,1 +577,1 @@
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- QStringList files_on_disk;
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+ QSet<QString> files_on_disk;
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@@ -629,1 +629,1 @@
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- files_on_disk << child_filepath;
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+ files_on_disk.insert(child_filepath);
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@@ -643,2 +643,2 @@
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- const QStringList files_on_disk_copy = files_on_disk;
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- for (const QString &file : files_on_disk_copy) {
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+ const QSet<QString> files_on_disk_copy = files_on_disk;
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+ for (const QString &file : files_on_disk_copy) {
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@@ -662,1 +662,1 @@
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- files_on_disk.removeAll(file);
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+ files_on_disk.remove(file);
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@@ -734,1 +734,1 @@
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- files_on_disk.removeAll(file);
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+ files_on_disk.remove(file);
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@@ -761,1 +761,1 @@
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- files_on_disk.removeAll(file);
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+ files_on_disk.remove(file);
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@@ -770,2 +770,1 @@
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- if (!t->files_changed_path_.contains(matching_filename)) {
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- t->files_changed_path_ << matching_filename;
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+ if (!t->files_changed_path_.contains(matching_filename)) {
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+ t->files_changed_path_.insert(matching_filename);
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@@ -793,1 +793,1 @@
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- files_on_disk.removeAll(file);
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+ files_on_disk.remove(file);
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@@ -805,1 +805,1 @@
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- files_on_disk.removeAll(file);
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+ files_on_disk.remove(file);
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