Bug 1787121: add support for formatting INI files to nsINIParser r=xpcom-reviewers,kmag

This allows callers to re-encode the data (eg: to UTF-16) and write or otherwise do with the formatted data as they wish.

I ended up adding/exposing additional init methods in part because I thought it made sense to support initialization from a string since we can now write to one, but also to make testing easier.

Differential Revision: https://phabricator.services.mozilla.com/D157377

xpcom/base/nsINIParser.cpp

@@ -294,15 +294,7 @@ nsresult nsINIParser::RenameSection(const char* aSection,
 nsresult nsINIParser::WriteToFile(nsIFile* aFile) {
   nsCString buffer;
 
-  for (const auto& entry : mSections) {
-    buffer.AppendPrintf("[%s]\n", entry.GetKey());
-    INIValue* val = entry.GetWeak();
-    while (val) {
-      buffer.AppendPrintf("%s=%s\n", val->key, val->value);
-      val = val->next.get();
-    }
-    buffer.AppendLiteral("\n");
-  }
+  WriteToString(buffer);
 
   FILE* writeFile;
   nsresult rv = aFile->OpenANSIFileDesc("w", &writeFile);
@@ -318,3 +310,15 @@ nsresult nsINIParser::WriteToFile(nsIFile* aFile) {
   fclose(writeFile);
   return NS_OK;
 }
+
+void nsINIParser::WriteToString(nsACString& aOutput) {
+  for (const auto& entry : mSections) {
+    aOutput.AppendPrintf("[%s]\n", entry.GetKey());
+    INIValue* val = entry.GetWeak();
+    while (val) {
+      aOutput.AppendPrintf("%s=%s\n", val->key, val->value);
+      val = val->next.get();
+    }
+    aOutput.AppendLiteral("\n");
+  }
+}

xpcom/base/nsINIParser.h

@@ -34,6 +34,8 @@ class nsINIParser {
    */
   nsresult Init(nsIFile* aFile);
 
+  nsresult InitFromString(const nsCString& aStr);
+
   /**
    * Callback for GetSections
    * @return false to stop enumeration, or true to continue.
@@ -134,6 +136,8 @@ class nsINIParser {
    */
   nsresult WriteToFile(nsIFile* aFile);
 
+  void WriteToString(nsACString& aOutput);
+
  private:
   struct INIValue {
     INIValue(const char* aKey, const char* aValue)
@@ -156,8 +160,6 @@ class nsINIParser {
 
   nsClassHashtable<nsCharPtrHashKey, INIValue> mSections;
 
-  nsresult InitFromString(const nsCString& aStr);
-
   bool IsValidSection(const char* aSection);
   bool IsValidKey(const char* aKey);
   bool IsValidValue(const char* aValue);

xpcom/ds/nsIINIParser.idl

@@ -10,6 +10,11 @@ interface nsIFile;
 [scriptable, uuid(7eb955f6-3e78-4d39-b72f-c1bf12a94bce)]
 interface nsIINIParser : nsISupports
 {
+  /**
+   * Initializes an INI file from string data
+   */
+  void initFromString(in AUTF8String aData);
+
   /**
    * Enumerates the [section]s available in the INI file.
    */
@@ -29,6 +34,7 @@ interface nsIINIParser : nsISupports
 [scriptable, uuid(b67bb24b-31a3-4a6a-a5d9-0485c9af5a04)]
 interface nsIINIParserWriter : nsISupports
 {
+
   /**
    * Set the value of a string for a particular section and key.
    */
@@ -38,6 +44,11 @@ interface nsIINIParserWriter : nsISupports
    * Write to the INI file.
    */
   void writeFile(in nsIFile aINIFile);
+
+  /**
+   * Return the formatted INI file contents
+   */
+  AUTF8String writeToString();
 };
 
 [scriptable, uuid(ccae7ea5-1218-4b51-aecb-c2d8ecd46af9)]

xpcom/ds/nsINIParserImpl.cpp

@@ -112,6 +112,11 @@ nsINIParserImpl::GetString(const nsACString& aSection, const nsACString& aKey,
                            PromiseFlatCString(aKey).get(), aResult);
 }
 
+NS_IMETHODIMP
+nsINIParserImpl::InitFromString(const nsACString& aData) {
+  return mParser.InitFromString(nsCString(aData));
+}
+
 NS_IMETHODIMP
 nsINIParserImpl::SetString(const nsACString& aSection, const nsACString& aKey,
                            const nsACString& aValue) {
@@ -128,3 +133,11 @@ NS_IMETHODIMP
 nsINIParserImpl::WriteFile(nsIFile* aINIFile) {
   return mParser.WriteToFile(aINIFile);
 }
+
+NS_IMETHODIMP
+nsINIParserImpl::WriteToString(nsACString& aOutput) {
+  aOutput.Truncate();
+  mParser.WriteToString(aOutput);
+
+  return NS_OK;
+}

xpcom/tests/unit/test_iniParser.js

@@ -257,8 +257,8 @@ function run_test() {
     );
     Assert.ok(!!factory);
 
-    // Test reading from a variety of files. While we're at it, write out each one
-    // and read it back to ensure that nothing changed.
+    // Test reading from a variety of files and strings. While we're at it,
+    // write out each one and read it back to ensure that nothing changed.
     while (testnum < testdata.length) {
       dump("\nINFO | test #" + ++testnum);
       let filename = testdata[testnum - 1].filename;
@@ -279,6 +279,15 @@ function run_test() {
       checkParserOutput(parser, testdata[testnum - 1].reference);
       // cleanup after the test
       newfile.remove(false);
+
+      // ensure that `writeString` works correctly
+      Assert.ok(parser instanceof Ci.nsIINIParserWriter);
+      let formatted = parser.writeToString();
+      parser = factory.createINIParser(null);
+      // re-parsing the formatted string is the easiest
+      // way to verify correctness...
+      parser.initFromString(formatted);
+      checkParserOutput(parser, testdata[testnum - 1].reference);
     }
 
     dump("INFO | test #" + ++testnum + "\n");