add append example

README.md

@@ -72,6 +72,7 @@ See the [examples directory](examples) for:
    * How to extract a zip file.
    * How to extract a single file from a zip.
    * How to read a zip from the standard input.
+   * How to append a directory to an existing archive
 
 Fuzzing
 -------

examples/append.rs

@@ -0,0 +1,68 @@
+use std::{
+    fs::{File, OpenOptions},
+    io::{Read, Write},
+    path::{Path, PathBuf},
+    str::FromStr,
+};
+use zip;
+
+fn gather_files<'a, T: Into<&'a Path>>(path: T, files: &mut Vec<PathBuf>) {
+    let path: &Path = path.into();
+
+    for entry in path.read_dir().unwrap() {
+        match entry {
+            Ok(e) => {
+                if e.path().is_dir() {
+                    gather_files(e.path().as_ref(), files);
+                } else if e.path().is_file() {
+                    files.push(e.path());
+                }
+            }
+            Err(_) => todo!(),
+        }
+    }
+}
+
+fn real_main() -> i32 {
+    let args: Vec<_> = std::env::args().collect();
+    if args.len() < 3 {
+        println!("Usage: {} <existing archive> <folder_to_append>", args[0]);
+        return 1;
+    }
+
+    let existing_archive_path = &*args[1];
+    let append_dir_path = &*args[2];
+    let archive = PathBuf::from_str(existing_archive_path).unwrap();
+    let to_append = PathBuf::from_str(append_dir_path).unwrap();
+
+    let existing_zip = OpenOptions::new()
+        .read(true)
+        .write(true)
+        .open(&archive)
+        .unwrap();
+    let mut append_zip = zip::ZipWriter::new_append(existing_zip).unwrap();
+
+    let mut files: Vec<PathBuf> = vec![];
+    gather_files(to_append.as_ref(), &mut files);
+
+    let mut buf: Vec<u8> = vec![];
+    for file in files {
+        append_zip
+            .start_file(file.to_string_lossy(), Default::default())
+            .unwrap();
+
+        let mut f = File::open(file).unwrap();
+        f.read_to_end(&mut buf).unwrap();
+
+        append_zip.write_all(&buf).unwrap();
+        buf.clear();
+    }
+
+    append_zip.finish().unwrap();
+
+    0
+}
+
+fn main() {
+    std::process::exit(real_main());
+}