Add {get,set}GitwebDescription to Repository

This method pair allows the caller to read and modify the description
file that is traditionally used by gitweb and cgit when rendering a
repository on the web.

Gerrit Code Review has offered this feature for years as part of
its GitRepositoryManager interface, but its fundamentally a feature
of JGit and its Repository abstraction.

git-core typically initializes a repository with a default value
inside the description file. During getDescription() this string
is converted to null as it is never a useful description.

Change-Id: I0a457026c74e9c73ea27e6f070d5fbaca3439be5

3 files changed, 87 insertions, 6 deletions

diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/internal/JGitText.java b/org.eclipse.jgit/src/org/eclipse/jgit/internal/JGitText.java
index 212cb7fdef..3577c4b286 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/internal/JGitText.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/internal/JGitText.java
@@ -734,6 +734,7 @@ public class JGitText extends TranslationBundle {
 	/***/ public String unsupportedOperationNotAddAtEnd;
 	/***/ public String unsupportedPackIndexVersion;
 	/***/ public String unsupportedPackVersion;
+	/***/ public String unsupportedRepositoryDescription;
 	/***/ public String updatingHeadFailed;
 	/***/ public String updatingReferences;
 	/***/ public String updatingRefFailed;
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/FileRepository.java b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/FileRepository.java
index 5b93399a76..ed1281bc6c 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/FileRepository.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/FileRepository.java
@@ -55,8 +55,10 @@ import java.io.IOException;
 import java.text.MessageFormat;
 import java.text.ParseException;
 import java.util.HashSet;
+import java.util.Objects;
 import java.util.Set;
 
+import org.eclipse.jgit.annotations.Nullable;
 import org.eclipse.jgit.api.errors.JGitInternalException;
 import org.eclipse.jgit.attributes.AttributesNode;
 import org.eclipse.jgit.attributes.AttributesNodeProvider;
@@ -85,6 +87,8 @@ import org.eclipse.jgit.storage.file.FileRepositoryBuilder;
 import org.eclipse.jgit.storage.pack.PackConfig;
 import org.eclipse.jgit.util.FS;
 import org.eclipse.jgit.util.FileUtils;
+import org.eclipse.jgit.util.IO;
+import org.eclipse.jgit.util.RawParseUtils;
 import org.eclipse.jgit.util.StringUtils;
 import org.eclipse.jgit.util.SystemReader;
 
@@ -114,16 +118,13 @@ import org.eclipse.jgit.util.SystemReader;
  *
  */
 public class FileRepository extends Repository {
-	private final FileBasedConfig systemConfig;
+	private static final String UNNAMED = "Unnamed repository; edit this file to name it for gitweb."; //$NON-NLS-1$
 
+	private final FileBasedConfig systemConfig;
 	private final FileBasedConfig userConfig;
-
 	private final FileBasedConfig repoConfig;
-
 	private final RefDatabase refs;
-
 	private final ObjectDirectory objectDatabase;
-
 	private FileSnapshot snapshot;
 
 	/**
@@ -420,6 +421,59 @@ public class FileRepository extends Repository {
 		return repoConfig;
 	}
 
+	@Override
+	@Nullable
+	public String getGitwebDescription() throws IOException {
+		String d;
+		try {
+			d = RawParseUtils.decode(IO.readFully(descriptionFile()));
+		} catch (FileNotFoundException err) {
+			return null;
+		}
+		if (d != null) {
+			d = d.trim();
+			if (d.isEmpty() || UNNAMED.equals(d)) {
+				return null;
+			}
+		}
+		return d;
+	}
+
+	@Override
+	public void setGitwebDescription(@Nullable String description)
+			throws IOException {
+		String old = getGitwebDescription();
+		if (Objects.equals(old, description)) {
+			return;
+		}
+
+		File path = descriptionFile();
+		LockFile lock = new LockFile(path);
+		if (!lock.lock()) {
+			throw new IOException(MessageFormat.format(JGitText.get().lockError,
+					path.getAbsolutePath()));
+		}
+		try {
+			String d = description;
+			if (d != null) {
+				d = d.trim();
+				if (!d.isEmpty()) {
+					d += '\n';
+				}
+			} else {
+				d = ""; //$NON-NLS-1$
+			}
+			lock.write(Constants.encode(d));
+			lock.commit();
+		} finally {
+			lock.unlock();
+		}
+	}
+
+	private File descriptionFile() {
+		return new File(getDirectory(), "description"); //$NON-NLS-1$
+	}
+
 	/**
 	 * Objects known to exist but not expressed by {@link #getAllRefs()}.
 	 * <p>
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/lib/Repository.java b/org.eclipse.jgit/src/org/eclipse/jgit/lib/Repository.java
index 1909037eeb..19d9610d0f 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/lib/Repository.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/lib/Repository.java
@@ -246,7 +246,6 @@ public abstract class Repository implements AutoCloseable {
 	@NonNull
 	public abstract AttributesNodeProvider createAttributesNodeProvider();
 
-
 	/**
 	 * @return the used file system abstraction, or or {@code null} if
 	 *         repository isn't local.
@@ -1437,6 +1436,33 @@ public abstract class Repository implements AutoCloseable {
 	}
 
 	/**
+	 * Read the {@code GIT_DIR/description} file for gitweb.
+	 *
+	 * @return description text; null if no description has been configured.
+	 * @throws IOException
+	 *             description cannot be accessed.
+	 * @since 4.6
+	 */
+	@Nullable
+	public String getGitwebDescription() throws IOException {
+		return null;
+	}
+
+	/**
+	 * Set the {@code GIT_DIR/description} file for gitweb.
+	 *
+	 * @param description
+	 *            new description; null to clear the description.
+	 * @throws IOException
+	 *             description cannot be persisted.
+	 * @since 4.6
+	 */
+	public void setGitwebDescription(@Nullable String description)
+			throws IOException {
+		throw new IOException(JGitText.get().unsupportedRepositoryDescription);
+	}
+
+	/**
 	 * @param refName
 	 * @return a {@link ReflogReader} for the supplied refname, or {@code null}
 	 *         if the named ref does not exist.