Bug 1725190 - Incorrect file extension when downloading CR3 files. r=jolin

Differential Revision: https://phabricator.services.mozilla.com/D127291

modules/libpref/init/StaticPrefList.yaml

@@ -8530,6 +8530,11 @@
 #endif
   mirror: always
 
+- name: media.mp4.sniff_iso_brand
+  type: RelaxedAtomicBool
+  value: true
+  mirror: always
+
 # Error/warning handling, Decoder Doctor.
 #
 # Set to true to force demux/decode warnings to be treated as errors.

toolkit/components/mediasniffer/nsMediaSniffer.cpp

@@ -8,6 +8,8 @@
 #include "mozilla/ArrayUtils.h"
 #include "mozilla/ModuleUtils.h"
 #include "mozilla/ScopeExit.h"
+#include "mozilla/StaticPrefs_media.h"
+#include "mozilla/Telemetry.h"
 #include "mp3sniff.h"
 #include "nestegg/nestegg.h"
 #include "nsHttpChannel.h"
@@ -61,27 +63,44 @@ nsMediaSnifferEntry nsMediaSniffer::sSnifferEntries[] = {
     PATTERN_ENTRY("\xFF\xFF\xFF\xFF\xFF\xFF\xFF", "#EXTM3U",
                   APPLICATION_MPEGURL)};
 
+using PatternLabel = mozilla::Telemetry::LABELS_MEDIA_SNIFFER_MP4_BRAND_PATTERN;
+
+struct nsMediaSnifferFtypEntry : nsMediaSnifferEntry {
+  nsMediaSnifferFtypEntry(nsMediaSnifferEntry aBase, const PatternLabel aLabel)
+      : nsMediaSnifferEntry(aBase), mLabel(aLabel) {}
+  PatternLabel mLabel;
+};
+
 // For a complete list of file types, see http://www.ftyps.com/index.html
-nsMediaSnifferEntry sFtypEntries[] = {
-    PATTERN_ENTRY("\xFF\xFF\xFF", "mp4", VIDEO_MP4),  // Could be mp41 or mp42.
-    PATTERN_ENTRY("\xFF\xFF\xFF", "avc",
-                  VIDEO_MP4),  // Could be avc1, avc2, ...
-    PATTERN_ENTRY("\xFF\xFF\xFF\xFF", "3gp4",
-                  VIDEO_MP4),  // 3gp4 is based on MP4
-    PATTERN_ENTRY("\xFF\xFF\xFF", "3gp",
-                  VIDEO_3GPP),  // Could be 3gp5, ...
-    PATTERN_ENTRY("\xFF\xFF\xFF\xFF", "M4V ", VIDEO_MP4),
-    PATTERN_ENTRY("\xFF\xFF\xFF\xFF", "M4A ", AUDIO_MP4),
-    PATTERN_ENTRY("\xFF\xFF\xFF\xFF", "M4P ", AUDIO_MP4),
-    PATTERN_ENTRY("\xFF\xFF\xFF\xFF", "qt  ", VIDEO_QUICKTIME),
-    PATTERN_ENTRY("\xFF\xFF\xFF", "iso", VIDEO_MP4),  // Could be isom or iso2.
-    PATTERN_ENTRY("\xFF\xFF\xFF\xFF", "mmp4", VIDEO_MP4),
-    PATTERN_ENTRY("\xFF\xFF\xFF\xFF", "avif", IMAGE_AVIF),
+nsMediaSnifferFtypEntry sFtypEntries[] = {
+    {PATTERN_ENTRY("\xFF\xFF\xFF", "mp4", VIDEO_MP4),
+     PatternLabel::ftyp_mp4},  // Could be mp41 or mp42.
+    {PATTERN_ENTRY("\xFF\xFF\xFF", "avc", VIDEO_MP4),
+     PatternLabel::ftyp_avc},  // Could be avc1, avc2, ...
+    {PATTERN_ENTRY("\xFF\xFF\xFF\xFF", "3gp4", VIDEO_MP4),
+     PatternLabel::ftyp_3gp4},  // 3gp4 is based on MP4
+    {PATTERN_ENTRY("\xFF\xFF\xFF", "3gp", VIDEO_3GPP),
+     PatternLabel::ftyp_3gp},  // Could be 3gp5, ...
+    {PATTERN_ENTRY("\xFF\xFF\xFF\xFF", "M4V ", VIDEO_MP4),
+     PatternLabel::ftyp_M4V},
+    {PATTERN_ENTRY("\xFF\xFF\xFF\xFF", "M4A ", AUDIO_MP4),
+     PatternLabel::ftyp_M4A},
+    {PATTERN_ENTRY("\xFF\xFF\xFF\xFF", "M4P ", AUDIO_MP4),
+     PatternLabel::ftyp_M4P},
+    {PATTERN_ENTRY("\xFF\xFF\xFF\xFF", "qt  ", VIDEO_QUICKTIME),
+     PatternLabel::ftyp_qt},
+    {PATTERN_ENTRY("\xFF\xFF\xFF", "iso", VIDEO_MP4),
+     PatternLabel::ftyp_iso},  // Could be isom or iso2.
+    {PATTERN_ENTRY("\xFF\xFF\xFF\xFF", "mmp4", VIDEO_MP4),
+     PatternLabel::ftyp_mmp4},
+    {PATTERN_ENTRY("\xFF\xFF\xFF\xFF", "avif", IMAGE_AVIF),
+     PatternLabel::ftyp_avif},
 };
 
 static bool MatchesBrands(const uint8_t aData[4], nsACString& aSniffedType) {
   for (size_t i = 0; i < mozilla::ArrayLength(sFtypEntries); ++i) {
     const auto& currentEntry = sFtypEntries[i];
+
     bool matched = true;
     MOZ_ASSERT(currentEntry.mLength <= 4,
                "Pattern is too large to match brand strings.");
@@ -92,7 +111,17 @@ static bool MatchesBrands(const uint8_t aData[4], nsACString& aSniffedType) {
       }
     }
     if (matched) {
+      // If we eventually remove the "iso" pattern entry per bug 1725190,
+      // this block should be removed and the bug1725190.cr3 test in
+      // test_mediasniffer_ext.js will need to be updated
+      if (!mozilla::StaticPrefs::media_mp4_sniff_iso_brand() &&
+          currentEntry.mLabel == PatternLabel::ftyp_iso) {
+        matched = false;
+        continue;
+      }
+
       aSniffedType.AssignASCII(currentEntry.mContentType);
+      AccumulateCategorical(currentEntry.mLabel);
       return true;
     }
   }

toolkit/components/mediasniffer/test/unit/test_mediasniffer_ext.js

@@ -44,7 +44,7 @@ const tests = [
   // An MP3 bytestream in a RIFF container, truncated to 512 bytes.
   { path: "data/mp3-in-riff.wav", expected: "audio/mpeg" },
   // The sniffing-relevant portion of a Canon raw image
-  { path: "data/bug1725190.cr3", expected: "application/octet-stream" },
+  { path: "data/bug1725190.cr3", expected: "video/mp4" },
 ];
 
 // A basic listener that reads checks the if we sniffed properly.

toolkit/components/telemetry/Histograms.json

@@ -10589,6 +10589,29 @@
     "description": "The operating system audio backend",
     "bug_numbers": [1671714, 1679745]
   },
+  "MEDIA_SNIFFER_MP4_BRAND_PATTERN": {
+    "record_in_processes": ["main", "content"],
+    "products": ["firefox", "geckoview_streaming"],
+    "alert_emails": ["jolin@mozilla.com", "jbauman@mozilla.com"],
+    "expires_in_version": "never",
+    "releaseChannelCollection": "opt-out",
+    "kind": "categorical",
+    "labels": [
+      "ftyp_mp4",
+      "ftyp_avc",
+      "ftyp_3gp4",
+      "ftyp_3gp",
+      "ftyp_M4V",
+      "ftyp_M4A",
+      "ftyp_M4P",
+      "ftyp_qt",
+      "ftyp_iso",
+      "ftyp_mmp4",
+      "ftyp_avif"
+    ],
+    "description": "ISOBMFF brand pattern used to identify MP4 in media sniffer",
+    "bug_numbers": [1725190]
+  },
   "WEBRTC_DTLS_CIPHER": {
     "record_in_processes": ["content", "socket"],
     "products": ["firefox"],