Treat bad values passed to --images as a fatal error

dm/DM.cpp

Index: dm/DM.cpp
diff --git a/dm/DM.cpp b/dm/DM.cpp
index eb40113a9b3d32ffcb15484769f36e969db5992a..02c66a88089d39e0a50fd2b3f373aa4efc541a0b 100644
--- a/dm/DM.cpp
+++ b/dm/DM.cpp
@@ -519,7 +519,7 @@ static bool brd_supported(const char* ext) {
     return false;
 }
 
-static void gather_srcs() {
+static bool gather_srcs() {
     for (const skiagm::GMRegistry* r = skiagm::GMRegistry::Head(); r; r = r->next()) {
         push_src("gm", "", new GMSrc(r->factory()));
     }
@@ -534,33 +534,25 @@ static void gather_srcs() {
             push_src("skp", "", new SKPSrc(path));
         }
     }
-    static const char* const exts[] = {
-        "bmp", "gif", "jpg", "jpeg", "png", "webp", "ktx", "astc", "wbmp", "ico",
-        "BMP", "GIF", "JPG", "JPEG", "PNG", "WEBP", "KTX", "ASTC", "WBMP", "ICO",
-#ifdef SK_CODEC_DECODES_RAW
-        "arw", "cr2", "dng", "nef", "nrw", "orf", "raf", "rw2", "pef", "srw",
-        "ARW", "CR2", "DNG", "NEF", "NRW", "ORF", "RAF", "RW2", "PEF", "SRW",
-#endif
-    };
-    for (int i = 0; i < FLAGS_images.count(); i++) {
-        const char* flag = FLAGS_images[i];
-        if (sk_isdir(flag)) {
-            for (size_t j = 0; j < SK_ARRAY_COUNT(exts); j++) {
-                SkOSFile::Iter it(flag, exts[j]);
-                for (SkString file; it.next(&file); ) {
-                    SkString path = SkOSPath::Join(flag, file.c_str());
-                    push_codec_srcs(path);
-                    if (brd_supported(exts[j])) {
-                        push_brd_srcs(path);
-                    }
-                }
-            }
-        } else if (sk_exists(flag)) {
-            // assume that FLAGS_images[i] is a valid image if it is a file.
-            push_codec_srcs(flag);
-            push_brd_srcs(flag);
+
+    SkTArray<SkString> images;
+    if (!CollectImages(&images)) {
+        return false;
+    }
+
+    for (auto image : images) {
+        push_codec_srcs(image);
+        const char* ext = "";
+        int index = image.findLastOf('.');
+        if (index >= 0 && (size_t) ++index < image.size()) {
+            ext = &image.c_str()[index];
+        }
+        if (brd_supported(ext)) {
+            push_brd_srcs(image);
         }
     }
+
+    return true;
 }
 
 static void push_sink(const SkCommandLineConfig& config, Sink* s) {
@@ -1108,7 +1100,9 @@ int dm_main() {
     gather_gold();
     gather_uninteresting_hashes();
 
-    gather_srcs();
+    if (!gather_srcs()) {
+        return 1;
+    }
     gather_sinks();
     gather_tests();