Allow to silently ignore signatures if the class is not found (#164)

Allow to silently ignore signatures if the class is not found (e.g., multi-module builds with common signatures). The old setting failOnUnresolvableSignatures was deprecated in favour of ignoreSignaturesOfMissingClasses. This closes #83

src/main/docs/ant-task.html

@@ -113,7 +113,15 @@ <h2>Parameters</h2>
   <td>failOnUnresolvableSignatures</td>
   <td><code>boolean</code></td>
   <td><code>true</code></td>
-  <td>Fail the build if a signature is not resolving. If this parameter is set to <code>false</code>, then such signatures are silently ignored.</td>
+  <td>Fail the build if a signature is not resolving. If this parameter is set to
+   to false, then such signatures are ignored.<br>
+   When disabling this setting, the task still prints a warning to inform the user about
+   broken signatures. This cannot be disabled. There is a second setting
+   <code>ignoreSignaturesOfMissingClasses</code> that can be used to silently ignore
+   signatures that refer to methods or field in classes that are not on classpath,
+   e.g. This is useful in multi-module builds where a common set of signatures is used,
+   that are not part of every sub-modules dependencies.<br>
+  <strong>Deprecated.</strong> Use <code>ignoreSignaturesOfMissingClasses</code> instead.</td>
 </tr>
 
 <tr>
@@ -137,6 +145,17 @@ <h2>Parameters</h2>
   <td>Ignore empty fileset/resource collection and print a warning instead.</td>
 </tr>
 
+<tr>
+  <td>ignoreSignaturesOfMissingClasses</td>
+  <td><code>boolean</code></td>
+  <td><code>false</code></td>
+  <td>If a class is missing while parsing signatures files, all methods and fields from this
+   class are silently ignored. This is useful in multi-module
+   projects where only some modules have the dependency to which the signature file(s) apply.
+   This settings prints no warning at all, so verify the signatures at least once with
+   full dependencies.</td>
+</tr>
+
 <tr>
   <td>suppressAnnotation</td>
   <td><code>class name</code></td>

src/main/java/de/thetaphi/forbiddenapis/Checker.java

@@ -54,6 +54,7 @@ public static enum Option {
     FAIL_ON_MISSING_CLASSES,
     FAIL_ON_VIOLATION,
     FAIL_ON_UNRESOLVABLE_SIGNATURES,
+    IGNORE_SIGNATURES_OF_MISSING_CLASSES,
     DISABLE_CLASSLOADING_CACHE
   }
 
@@ -341,6 +342,11 @@ public boolean hasNoSignatures() {
     return forbiddenSignatures.hasNoSignatures();
   }
 
+  /** Returns if no signatures files / inline signatures were parsed */
+  public boolean noSignaturesFilesParsed() {
+    return forbiddenSignatures.noSignaturesFilesParsed();
+  }
+
   /** Parses and adds a class from the given stream to the list of classes to check. Closes the stream when parsed (on Exception, too)! Does not log anything. */
   public void addClassToCheck(final InputStream in, String name) throws IOException {
     final ClassReader reader;

src/main/java/de/thetaphi/forbiddenapis/Constants.java

@@ -28,6 +28,9 @@ public interface Constants {
 
   final Pattern JDK_SIG_PATTERN = Pattern.compile("(jdk\\-.*?\\-)(\\d+)(\\.\\d+)?(\\.\\d+)*");
 
+  final String DEPRECATED_WARN_FAIL_ON_UNRESOLVABLE_SIGNATURES =
+      "The setting 'failOnUnresolvableSignatures' was deprecated and will be removed in next version. Use 'ignoreSignaturesOfMissingClasses' instead.";
+
   final Type DEPRECATED_TYPE = Type.getType(Deprecated.class);
   final String DEPRECATED_DESCRIPTOR = DEPRECATED_TYPE.getDescriptor();
 

src/main/java/de/thetaphi/forbiddenapis/Signatures.java

@@ -47,6 +47,7 @@ public final class Signatures implements Constants {
   private static final String BUNDLED_PREFIX = "@includeBundled ";
   private static final String DEFAULT_MESSAGE_PREFIX = "@defaultMessage ";
   private static final String IGNORE_UNRESOLVABLE_LINE = "@ignoreUnresolvable";
+  private static final String IGNORE_MISSING_CLASSES_LINE = "@ignoreMissingClasses";
 
   private static enum UnresolvableReporting {
     FAIL(true) {
@@ -78,7 +79,7 @@ private UnresolvableReporting(boolean reportClassNotFound) {
 
   private final RelatedClassLookup lookup;
   private final Logger logger;
-  private final boolean failOnUnresolvableSignatures;
+  private final boolean failOnUnresolvableSignatures, ignoreSignaturesOfMissingClasses;
 
   /** Key is used to lookup forbidden signature in following formats. Keys are generated by the corresponding
    * {@link #getKey(String)} (classes), {@link #getKey(String, Method)} (methods),
@@ -91,14 +92,18 @@ private UnresolvableReporting(boolean reportClassNotFound) {
 
   /** if enabled, the bundled signature to enable heuristics for detection of non-portable runtime calls is used */
   private boolean forbidNonPortableRuntime = false;
+
+  /** number of files that were interpreted as signatures file. If 0, no (bundled) signatures files were added at all */
+  private int numberOfFiles = 0;
 
   public Signatures(Checker checker) {
-    this(checker, checker.logger, checker.options.contains(Option.FAIL_ON_UNRESOLVABLE_SIGNATURES));
+    this(checker, checker.logger, checker.options.contains(Option.IGNORE_SIGNATURES_OF_MISSING_CLASSES), checker.options.contains(Option.FAIL_ON_UNRESOLVABLE_SIGNATURES));
   }
 
-  public Signatures(RelatedClassLookup lookup, Logger logger, boolean failOnUnresolvableSignatures) {
+  public Signatures(RelatedClassLookup lookup, Logger logger, boolean ignoreSignaturesOfMissingClasses, boolean failOnUnresolvableSignatures) {
     this.lookup = lookup;
     this.logger = logger;
+    this.ignoreSignaturesOfMissingClasses = ignoreSignaturesOfMissingClasses;
     this.failOnUnresolvableSignatures = failOnUnresolvableSignatures;
   }
 
@@ -115,7 +120,8 @@ static String getKey(String internalClassName, Method method) {
   }
 
   /** Adds the method signature to the list of disallowed methods. The Signature is checked against the given ClassLoader. */
-  private void addSignature(final String line, final String defaultMessage, final UnresolvableReporting report, final Set<String> missingClasses) throws ParseException,IOException {
+  private void addSignature(final String line, final String defaultMessage, final UnresolvableReporting report,
+      final boolean localIgnoreMissingClasses, final Set<String> missingClasses) throws ParseException,IOException {
     final String clazz, field, signature;
     String message = null;
     final Method method;
@@ -171,6 +177,9 @@ private void addSignature(final String line, final String defaultMessage, final
       try {
         c = lookup.getClassFromClassLoader(clazz);
       } catch (ClassNotFoundException cnfe) {
+        if (this.ignoreSignaturesOfMissingClasses || localIgnoreMissingClasses) {
+          return;
+        }
         if (report.reportClassNotFound) {
           report.parseFailed(logger, String.format(Locale.ENGLISH, "Class '%s' not found on classpath", cnfe.getMessage()), signature);
         } else {
@@ -235,6 +244,7 @@ private void addBundledSignatures(String name, String jdkTargetVersion, boolean
     }
     if (BS_JDK_NONPORTABLE.equals(name)) {
       if (logging) logger.info("Reading bundled API signatures: " + name);
+      numberOfFiles++;
       forbidNonPortableRuntime = true;
       return;
     }
@@ -254,14 +264,16 @@ private void addBundledSignatures(String name, String jdkTargetVersion, boolean
     parseSignaturesStream(in, true, missingClasses);
   }
 
-  private void parseSignaturesStream(InputStream in, boolean allowBundled, Set<String> missingClasses) throws IOException,ParseException {
-    parseSignaturesFile(new InputStreamReader(in, StandardCharsets.UTF_8), allowBundled, missingClasses);
+  private void parseSignaturesStream(InputStream in, boolean isBundled, Set<String> missingClasses) throws IOException,ParseException {
+    parseSignaturesFile(new InputStreamReader(in, StandardCharsets.UTF_8), isBundled, missingClasses);
   }
 
   private void parseSignaturesFile(Reader reader, boolean isBundled, Set<String> missingClasses) throws IOException,ParseException {
+    numberOfFiles++;
     try (final BufferedReader r = new BufferedReader(reader)) {
       String line, defaultMessage = null;
       UnresolvableReporting reporter = failOnUnresolvableSignatures ? UnresolvableReporting.FAIL : UnresolvableReporting.WARNING;
+      boolean localIgnoreMissingClasses = false;
       while ((line = r.readLine()) != null) {
         line = line.trim();
         if (line.length() == 0 || line.startsWith("#"))
@@ -274,12 +286,20 @@ private void parseSignaturesFile(Reader reader, boolean isBundled, Set<String> m
             defaultMessage = line.substring(DEFAULT_MESSAGE_PREFIX.length()).trim();
             if (defaultMessage.length() == 0) defaultMessage = null;
           } else if (line.equals(IGNORE_UNRESOLVABLE_LINE)) {
-            reporter = isBundled ? UnresolvableReporting.SILENT : UnresolvableReporting.WARNING;
+            if (isBundled) {
+              reporter = UnresolvableReporting.SILENT;
+            } else {
+              logger.warn(String.format(Locale.ENGLISH, "'%s' inside signatures files is deprecated, prefer using '%s' to ignore signatures where the class is missing.",
+                  IGNORE_UNRESOLVABLE_LINE, IGNORE_MISSING_CLASSES_LINE));
+              reporter = UnresolvableReporting.WARNING;
+            }
+          } else if (line.equals(IGNORE_MISSING_CLASSES_LINE)) {
+            localIgnoreMissingClasses = true;
           } else {
             throw new ParseException("Invalid line in signature file: " + line);
           }
         } else {
-          addSignature(line, defaultMessage, reporter, missingClasses);
+          addSignature(line, defaultMessage, reporter, localIgnoreMissingClasses, missingClasses);
         }
       }
     }
@@ -315,6 +335,11 @@ public boolean hasNoSignatures() {
         (forbidNonPortableRuntime ? 1 : 0);
   }
 
+  /** Returns if no signatures files / inline signatures were parsed */
+  public boolean noSignaturesFilesParsed() {
+    return numberOfFiles == 0;
+  }
+
   /** Returns if bundled signature to enable heuristics for detection of non-portable runtime calls is used */
   public boolean isNonPortableRuntimeForbidden() {
     return this.forbidNonPortableRuntime;

src/main/java/de/thetaphi/forbiddenapis/ant/AntTask.java

@@ -67,6 +67,7 @@ public class AntTask extends Task implements Constants {
   private boolean restrictClassFilename = true;
   private boolean failOnMissingClasses = true;
   private boolean failOnUnresolvableSignatures = true;
+  private boolean ignoreSignaturesOfMissingClasses = false;
   private boolean failOnViolation = true;
   private boolean ignoreEmptyFileset = false;
   private String targetVersion = null;
@@ -108,7 +109,12 @@ public void info(String msg) {
       final EnumSet<Checker.Option> options = EnumSet.noneOf(Checker.Option.class);
       if (failOnMissingClasses) options.add(FAIL_ON_MISSING_CLASSES);
       if (failOnViolation) options.add(FAIL_ON_VIOLATION);
-      if (failOnUnresolvableSignatures) options.add(FAIL_ON_UNRESOLVABLE_SIGNATURES);
+      if (failOnUnresolvableSignatures) {
+        options.add(FAIL_ON_UNRESOLVABLE_SIGNATURES);
+      } else {
+        log.warn(DEPRECATED_WARN_FAIL_ON_UNRESOLVABLE_SIGNATURES);
+      }
+      if (ignoreSignaturesOfMissingClasses) options.add(IGNORE_SIGNATURES_OF_MISSING_CLASSES);
       if (disableClassloadingCache) options.add(DISABLE_CLASSLOADING_CACHE);
       final Checker checker = new Checker(log, loader, options);
 
@@ -169,7 +175,12 @@ public void info(String msg) {
       }
 
       if (checker.hasNoSignatures()) {
-        throw new BuildException("No API signatures found; use signaturesFile=, <signatures*/>, <bundledSignatures/> or inner text to define those!");
+        if (checker.noSignaturesFilesParsed()) {
+          throw new BuildException("No signatures were added to task; use signaturesFile=, <signatures*/>, <bundledSignatures/> or inner text to define those!");
+        } else {
+          log.info("Skipping execution because no API signatures are available.");
+          return;
+        }
       }
 
       log.info("Loading classes to check...");
@@ -325,13 +336,34 @@ public void setFailOnMissingClasses(boolean failOnMissingClasses) {
 
   /**
    * Fail the build if a signature is not resolving. If this parameter is set to
-   * to false, then such signatures are silently ignored.
-   * Defaults to {@code true}. 
+   * to false, then such signatures are ignored. Defaults to {@code true}.
+   * <p>When disabling this setting, the task still prints a warning to inform the user about
+   * broken signatures. This cannot be disabled. There is a second setting
+   * {@link #setIgnoreMissingSignaturesClasses()} that can be used to silently ignore
+   * signatures that refer to methods or field in classes that are not on classpath,
+   * e.g. This is useful in multi-module builds where a common set of signatures is used,
+   * that are not part of every sub-modules dependencies.
+   * @see #setIgnoreMissingSignaturesClasses()
+   * @deprecated Use {@link #setIgnoreSignaturesOfMissingClasses(boolean)} instead.
    */
+  @Deprecated
   public void setFailOnUnresolvableSignatures(boolean failOnUnresolvableSignatures) {
     this.failOnUnresolvableSignatures = failOnUnresolvableSignatures;
   }
 
+  /**
+   * If a class is missing while parsing signatures files, all methods and fields from this
+   * class are silently ignored. This is useful in multi-module
+   * projects where only some modules have the dependency to which the signature file(s) apply.
+   * This settings prints no warning at all, so verify the signatures at least once with
+   * full dependencies.
+   * Defaults to {@code false}.
+   * @since 3.0
+   */
+  public void setIgnoreSignaturesOfMissingClasses(boolean ignoreSignaturesOfMissingClasses) {
+    this.ignoreSignaturesOfMissingClasses = ignoreSignaturesOfMissingClasses;
+  }
+
   /** Automatically restrict resource names included to files with a name ending in '.class'.
    * This makes filesets easier, as the includes="**&#47;*.class" is not needed.
    * Defaults to {@code true}.

src/main/java/de/thetaphi/forbiddenapis/cli/CliMain.java

@@ -53,7 +53,7 @@
 public final class CliMain implements Constants {
 
   private final Option classpathOpt, dirOpt, includesOpt, excludesOpt, signaturesfileOpt, bundledsignaturesOpt, suppressannotationsOpt,
-    allowmissingclassesOpt, allowunresolvablesignaturesOpt, versionOpt, helpOpt;
+    allowmissingclassesOpt, ignoresignaturesofmissingclassesOpt, allowunresolvablesignaturesOpt, versionOpt, helpOpt;
   private final CommandLine cmd;
 
   private static final Logger LOG = StdIoLogger.INSTANCE;
@@ -129,8 +129,12 @@ public CliMain(String... args) throws ExitException {
         .desc("don't fail if a referenced class is missing on classpath")
         .longOpt("allowmissingclasses")
         .build());
+    options.addOption(ignoresignaturesofmissingclassesOpt = Option.builder()
+        .desc("if a class is missing while parsing signatures files, all methods and fields from this class are silently ignored")
+        .longOpt("ignoresignaturesofmissingclasses")
+        .build());
     options.addOption(allowunresolvablesignaturesOpt = Option.builder()
-        .desc("don't fail if a signature is not resolving")
+        .desc("DEPRECATED: don't fail if a signature is not resolving")
         .longOpt("allowunresolvablesignatures")
         .build());
 
@@ -212,7 +216,12 @@ public void run() throws ExitException {
     try (final URLClassLoader loader = URLClassLoader.newInstance(urls, ClassLoader.getSystemClassLoader())) {
       final EnumSet<Checker.Option> options = EnumSet.of(FAIL_ON_VIOLATION);
       if (!cmd.hasOption(allowmissingclassesOpt.getLongOpt())) options.add(FAIL_ON_MISSING_CLASSES);
-      if (!cmd.hasOption(allowunresolvablesignaturesOpt.getLongOpt())) options.add(FAIL_ON_UNRESOLVABLE_SIGNATURES);
+      if (cmd.hasOption(allowunresolvablesignaturesOpt.getLongOpt())) {
+        LOG.warn(DEPRECATED_WARN_FAIL_ON_UNRESOLVABLE_SIGNATURES);
+      } else {
+        options.add(FAIL_ON_UNRESOLVABLE_SIGNATURES);
+      }
+      if (cmd.hasOption(ignoresignaturesofmissingclassesOpt.getLongOpt())) options.add(IGNORE_SIGNATURES_OF_MISSING_CLASSES);
       final Checker checker = new Checker(LOG, loader, options);
 
       if (!checker.isSupportedJDK) {
@@ -267,10 +276,15 @@ public void run() throws ExitException {
       }
 
       if (checker.hasNoSignatures()) {
-        throw new ExitException(EXIT_ERR_CMDLINE, String.format(Locale.ENGLISH,
-          "No API signatures found; use parameters '--%s' and/or '--%s' to specify those!",
-          bundledsignaturesOpt.getLongOpt(), signaturesfileOpt.getLongOpt()
-        ));
+        if (checker.noSignaturesFilesParsed()) {
+          throw new ExitException(EXIT_ERR_CMDLINE, String.format(Locale.ENGLISH,
+            "No API signatures given as parameters; use '--%s' and/or '--%s' to specify those!",
+            bundledsignaturesOpt.getLongOpt(), signaturesfileOpt.getLongOpt()
+          ));
+      } else {
+          LOG.info("Skipping execution because no API signatures are available.");
+          return;
+        }
       }
 
       try {