stage

problems/p9/Cargo.toml

@@ -0,0 +1,6 @@
+[package]
+name = "p9"
+version = "0.1.0"
+edition = "2024"
+
+[dependencies]

problems/p9/src/main.rs

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+fn pkcs7_padding(data: &mut Vec<u8>, block_size: usize) {
+    if block_size == 0 {
+        panic!("Block size must be greater than zero");
+    }
+    if block_size > 255 {
+        panic!("Block size must be less than or equal to 255");
+    }
+    let mut padding_length = block_size - (data.len() % block_size);
+    if padding_length == 0 {
+        padding_length = block_size;
+    }
+    data.extend(vec![padding_length as u8; padding_length]);
+}
+
+fn main() {
+    let mut plain_text = b"YELLOW SUBMARINE".to_vec();
+    pkcs7_padding(&mut plain_text, 20);
+
+    println!("Padded text: {:?}", plain_text);
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_normal_padding() {
+        let mut data = b"YELLOW SUBMARINE".to_vec(); // 16 bytes
+        pkcs7_padding(&mut data, 20);
+        assert_eq!(data.len(), 20);
+        assert_eq!(&data[16..], &[4, 4, 4, 4]);
+    }
+
+    #[test]
+    fn test_full_block_padding() {
+        let mut data = b"YELLOW".to_vec(); // 6 bytes
+        pkcs7_padding(&mut data, 6);
+        assert_eq!(data.len(), 12);
+        assert_eq!(&data[6..], &[6, 6, 6, 6, 6, 6]);
+    }
+
+    #[test]
+    fn test_single_byte_padding() {
+        let mut data = b"YELLOW SUBMARIN".to_vec(); // 15 bytes
+        pkcs7_padding(&mut data, 16);
+        assert_eq!(data.len(), 16);
+        assert_eq!(data[15], 1);
+    }
+
+    #[test]
+    fn test_empty_data() {
+        let mut data = Vec::new();
+        pkcs7_padding(&mut data, 8);
+        assert_eq!(data.len(), 8);
+        assert_eq!(data, vec![8; 8]);
+    }
+
+    #[test]
+    #[should_panic(expected = "Block size must be greater than zero")]
+    fn test_zero_block_size() {
+        let mut data = b"test".to_vec();
+        pkcs7_padding(&mut data, 0);
+    }
+
+    #[test]
+    #[should_panic(expected = "Block size must be less than or equal to 255")]
+    fn test_oversized_block() {
+        let mut data = b"test".to_vec();
+        pkcs7_padding(&mut data, 256);
+    }
+
+    #[test]
+    fn test_boundary_block_size() {
+        let mut data = b"A".to_vec();
+        pkcs7_padding(&mut data, 255);
+        assert_eq!(data.len(), 255);
+        assert_eq!(&data[1..], vec![254; 254]);
+    }
+}