Add is_writing_file and update doc

CHANGELOG.md

@@ -74,4 +74,16 @@
 
 ### Fixed
 
-- Fixed a possible bug in deep_copy_file.
+ - Fixed a possible bug in deep_copy_file.
+
+## [0.7.0]
+
+### Fixed
+
+ - Calling `start_file` with invalid parameters no longer closes the `ZipWriter`.
+ - Attempting to write a 4GiB file without calling `FileOptions::large_file(true)` now removes the file from the archive
+   but does not close the `ZipWriter`.
+
+### Added
+
+ - Method `is_writing_file` - indicates whether a file is open for writing.

src/write.rs

@@ -227,7 +227,8 @@ impl<W: Write + Seek> Write for ZipWriter<W> {
                             && !self.files.last_mut().unwrap().large_file
                         {
                             self.finish_file()?;
-                            self.files_by_name.remove(&*self.files.pop().unwrap().file_name);
+                            self.files_by_name
+                                .remove(&*self.files.pop().unwrap().file_name);
                             return Err(io::Error::new(
                                 io::ErrorKind::Other,
                                 "Large file option has not been set",
@@ -355,6 +356,8 @@ impl<W: Write + Seek> ZipWriter<W> {
     /// Initializes the archive.
     ///
     /// Before writing to this object, the [`ZipWriter::start_file`] function should be called.
+    /// After a successful write, the file remains open for writing. After a failed write, call
+    /// [`ZipWriter::is_writing_file`] to determine if the file remains open.
     pub fn new(inner: W) -> ZipWriter<W> {
         ZipWriter {
             inner: Storer(inner),
@@ -369,6 +372,11 @@ impl<W: Write + Seek> ZipWriter<W> {
         }
     }
 
+    /// Returns true if a file is currently open for writing.
+    pub fn is_writing_file(&self) -> bool {
+        self.writing_to_file && !self.inner.is_closed()
+    }
+
     /// Set ZIP archive comment.
     pub fn set_comment<S>(&mut self, comment: S)
     where