Support command line parameters to specify a url to file name mapping. This is used during snapsh...

bin/gen_snapshot.cc

Index: bin/gen_snapshot.cc
===================================================================
--- bin/gen_snapshot.cc	(revision 1549)
+++ bin/gen_snapshot.cc	(working copy)
@@ -20,6 +20,9 @@
 // if so which file to write the snapshot into.
 static const char* snapshot_filename = NULL;
 
+// Global state that captures the URL mappings specified on the command line.
+static CommandLineOptions* url_mapping = NULL;
+
 static bool IsValidFlag(const char* name,
                         const char* prefix,
                         intptr_t prefix_length) {
@@ -40,11 +43,26 @@
 
 static bool ProcessSnapshotOption(const char* option) {
   const char* kSnapshotOption = "--snapshot=";
-  snapshot_filename = ProcessOption(option, kSnapshotOption);
-  return snapshot_filename != NULL;
+  const char* name = ProcessOption(option, kSnapshotOption);
+  if (name != NULL) {
+    snapshot_filename = name;
+    return true;
+  }
+  return false;
 }
 
 
+static bool ProcessURLmappingOption(const char* option) {
+  const char* kURLmappingOption = "--url_mapping=";
+  const char* mapping = ProcessOption(option, kURLmappingOption);
+  if (mapping != NULL) {
+    url_mapping->AddArgument(mapping);
+    return true;
+  }
+  return false;
+}
+
+
 // Parse out the command line arguments. Returns -1 if the arguments
 // are incorrect, 0 otherwise.
 static int ParseArguments(int argc,
@@ -59,7 +77,7 @@
 
   // Parse out the vm options.
   while ((i < argc) && IsValidFlag(argv[i], kPrefix, kPrefixLen)) {
-    if (ProcessSnapshotOption(argv[i])) {
+    if (ProcessSnapshotOption(argv[i]) || ProcessURLmappingOption(argv[i])) {
       i += 1;
       continue;
     }
@@ -90,6 +108,118 @@
 }
 
 
+static const char* MapLibraryUrl(const char* library_url_chars) {
+  const char* mapped_url_chars = NULL;
+  if (url_mapping != NULL) {
+    // We need to check if the passed in url is found in the url_mapping array,
+    // in that case use the mapped entry.
+    int len = strlen(library_url_chars);
+    for (int idx = 0; idx < url_mapping->count(); idx++) {
+      const char* url_name = url_mapping->GetArgument(idx);
+      if (!strncmp(library_url_chars, url_name, len) &&
+          (url_name[len] == ',')) {
+        const char* url_mapped_name = url_name + len + 1;
+        if (strlen(url_mapped_name) != 0) {
+          mapped_url_chars = url_mapped_name;
+        }
+        break;
+      }
+    }
+  }
+  return mapped_url_chars;
+}
+
+
+static Dart_Handle CanonicalizeUrl(const char* library_url_chars,
+                                   const char* url_chars) {
+  // Calculate the canonical path based on the importing library and the url.
+  const char* canonical_filename = GetCanonicalPath(library_url_chars,
+                                                    url_chars);
+  Dart_Handle canon_url = Dart_NewString(canonical_filename);
+  free(const_cast<char*>(canonical_filename));
+  return canon_url;
+}
+
+
+static Dart_Handle CreateSnapshotLibraryTagHandler(Dart_LibraryTag tag,
+                                                   Dart_Handle library,
+                                                   Dart_Handle url) {
+  if (!Dart_IsLibrary(library)) {
+    return Dart_Error("not a library");
+  }
+  if (!Dart_IsString8(url)) {
+    return Dart_Error("url is not a string");
+  }
+  const char* url_chars = NULL;
+  Dart_Handle result = Dart_StringToCString(url, &url_chars);
+  if (Dart_IsError(result)) {
+    return Dart_Error("accessing url characters failed");
+  }
+
+  // If the URL starts with "dart:" then it is handled specially.
+  static const char* kDartScheme = "dart:";
+  static const intptr_t kDartSchemeLen = strlen(kDartScheme);
+  if (strncmp(url_chars, kDartScheme, kDartSchemeLen) == 0) {
+    if (tag == kCanonicalizeUrl) {
+      return Dart_NewString(url_chars);
+    }
+    const char* mapped_url_chars = MapLibraryUrl(url_chars);
+    if (mapped_url_chars != NULL) {
+      // We have a URL mapping specified, just return the mapped version.
+      return Dart_NewString(mapped_url_chars);
+    }
+  }
+  // Get the url of the calling library.
+  Dart_Handle library_url = Dart_LibraryUrl(library);
+  if (Dart_IsError(library_url)) {
+    return Dart_Error("accessing library url failed");
+  }
+  if (!Dart_IsString8(library_url)) {
+    return Dart_Error("library url is not a string");
+  }
+  const char* library_url_chars = NULL;
+  result = Dart_StringToCString(library_url, &library_url_chars);
+  if (Dart_IsError(result)) {
+    return Dart_Error("accessing library url characters failed");
+  }
+  library_url_chars = MapLibraryUrl(library_url_chars);
+  Dart_Handle canon_url = CanonicalizeUrl(library_url_chars, url_chars);
+  if (Dart_IsError(canon_url)) {
+    return canon_url;  // canon_url contains the error string.
+  }
+  if (tag == kCanonicalizeUrl) {
+    return canon_url;
+  }
+  result = Dart_StringToCString(canon_url, &url_chars);
+  if (Dart_IsError(result)) {
+    return Dart_Error("accessing canon url characters failed");
+  }
+  // The tag is either an import or a source tag. Read the file based on the
+  // url chars.
+  Dart_Handle source = ReadStringFromFile(url_chars);
+  if (Dart_IsError(source)) {
+    return source;  // source contains the error string.
+  }
+  if (tag == kImportTag) {
+    return Dart_LoadLibrary(url, source);
+  } else if (tag == kSourceTag) {
+    return Dart_LoadSource(library, url, source);
+  }
+  return Dart_Error("wrong tag");
+}
+
+
+static Dart_Handle LoadSnapshotCreationScript(const char* script_name) {
+  Dart_Handle source = ReadStringFromFile(script_name);
+  if (Dart_IsError(source)) {
+    return source;  // source contains the error string.
+  }
+  Dart_Handle url = Dart_NewString(script_name);
+
+  return Dart_LoadScript(url, source, CreateSnapshotLibraryTagHandler);
+}
+
+
 static void* SnapshotCreateCallback(void* data) {
   const char* script_name = reinterpret_cast<const char*>(data);
   Dart_Handle result;
@@ -151,6 +281,10 @@
   CommandLineOptions vm_options(argc);
   char* script_name;
 
+  // Initialize the URL mapping array.
+  CommandLineOptions url_mapping_array(argc);
+  url_mapping = &url_mapping_array;
+
   // Parse command line arguments.
   if (ParseArguments(argc,
                      argv,
@@ -165,9 +299,10 @@
     return 255;
   }
 
-  // Initialize the Dart VM.
+  // Initialize the Dart VM (TODO(asiva) - remove const_cast once
+  // dart API is fixed to take a const char** in Dart_Initialize).
   Dart_Initialize(vm_options.count(),
-                  vm_options.arguments(),
+                  const_cast<char**>(vm_options.arguments()),
                   SnapshotCreateCallback);
 
   // Create an isolate. As a side effect, SnapshotCreateCallback