Improve error handling in libflate

This removes the error case of the compression functions, the only errors that
can occur are incorrect parameters or an out-of-memory condition, both of which
are handled with panics in Rust.

Also introduces an extensible `Error` type instead of returning an `Option`.

Author: tbu-

src/libflate/lib.rs

@@ -25,7 +25,6 @@
        html_favicon_url = "http://www.rust-lang.org/favicon.ico",
        html_root_url = "http://doc.rust-lang.org/nightly/")]
 
-#![feature(int_uint)]
 #![feature(libc)]
 #![feature(staged_api)]
 #![feature(unique)]
@@ -35,13 +34,33 @@
 extern crate libc;
 
 use libc::{c_void, size_t, c_int};
+use std::fmt;
 use std::ops::Deref;
 use std::ptr::Unique;
 use std::slice;
 
+#[derive(Clone, Eq, Hash, Ord, PartialEq, PartialOrd)]
+pub struct Error {
+    _unused: (),
+}
+
+impl Error {
+    fn new() -> Error {
+        Error {
+            _unused: (),
+        }
+    }
+}
+
+impl fmt::Debug for Error {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        "decompression error".fmt(f)
+    }
+}
+
 pub struct Bytes {
     ptr: Unique<u8>,
-    len: uint,
+    len: usize,
 }
 
 impl Deref for Bytes {
@@ -78,55 +97,56 @@ const LZ_NORM: c_int = 0x80;  // LZ with 128 probes, "normal"
 const TINFL_FLAG_PARSE_ZLIB_HEADER: c_int = 0x1; // parse zlib header and adler32 checksum
 const TDEFL_WRITE_ZLIB_HEADER: c_int = 0x01000; // write zlib header and adler32 checksum
 
-fn deflate_bytes_internal(bytes: &[u8], flags: c_int) -> Option<Bytes> {
+fn deflate_bytes_internal(bytes: &[u8], flags: c_int) -> Bytes {
     unsafe {
-        let mut outsz : size_t = 0;
+        let mut outsz: size_t = 0;
         let res = tdefl_compress_mem_to_heap(bytes.as_ptr() as *const _,
                                              bytes.len() as size_t,
                                              &mut outsz,
                                              flags);
-        if !res.is_null() {
-            let res = Unique::new(res as *mut u8);
-            Some(Bytes { ptr: res, len: outsz as uint })
-        } else {
-            None
+        assert!(!res.is_null());
+        Bytes {
+            ptr: Unique::new(res as *mut u8),
+            len: outsz as usize,
         }
     }
 }
 
 /// Compress a buffer, without writing any sort of header on the output.
-pub fn deflate_bytes(bytes: &[u8]) -> Option<Bytes> {
+pub fn deflate_bytes(bytes: &[u8]) -> Bytes {
     deflate_bytes_internal(bytes, LZ_NORM)
 }
 
 /// Compress a buffer, using a header that zlib can understand.
-pub fn deflate_bytes_zlib(bytes: &[u8]) -> Option<Bytes> {
+pub fn deflate_bytes_zlib(bytes: &[u8]) -> Bytes {
     deflate_bytes_internal(bytes, LZ_NORM | TDEFL_WRITE_ZLIB_HEADER)
 }
 
-fn inflate_bytes_internal(bytes: &[u8], flags: c_int) -> Option<Bytes> {
+fn inflate_bytes_internal(bytes: &[u8], flags: c_int) -> Result<Bytes,Error> {
     unsafe {
-        let mut outsz : size_t = 0;
+        let mut outsz: size_t = 0;
         let res = tinfl_decompress_mem_to_heap(bytes.as_ptr() as *const _,
                                                bytes.len() as size_t,
                                                &mut outsz,
                                                flags);
         if !res.is_null() {
-            let res = Unique::new(res as *mut u8);
-            Some(Bytes { ptr: res, len: outsz as uint })
+            Ok(Bytes {
+                ptr: Unique::new(res as *mut u8),
+                len: outsz as usize,
+            })
         } else {
-            None
+            Err(Error::new())
         }
     }
 }
 
 /// Decompress a buffer, without parsing any sort of header on the input.
-pub fn inflate_bytes(bytes: &[u8]) -> Option<Bytes> {
+pub fn inflate_bytes(bytes: &[u8]) -> Result<Bytes,Error> {
     inflate_bytes_internal(bytes, 0)
 }
 
 /// Decompress a buffer that starts with a zlib header.
-pub fn inflate_bytes_zlib(bytes: &[u8]) -> Option<Bytes> {
+pub fn inflate_bytes_zlib(bytes: &[u8]) -> Result<Bytes,Error> {
     inflate_bytes_internal(bytes, TINFL_FLAG_PARSE_ZLIB_HEADER)
 }
 
@@ -140,7 +160,7 @@ mod tests {
     #[test]
     fn test_flate_round_trip() {
         let mut r = rand::thread_rng();
-        let mut words = vec!();
+        let mut words = vec![];
         for _ in 0..20 {
             let range = r.gen_range(1, 10);
             let v = r.gen_iter::<u8>().take(range).collect::<Vec<u8>>();
@@ -153,8 +173,8 @@ mod tests {
             }
             debug!("de/inflate of {} bytes of random word-sequences",
                    input.len());
-            let cmp = deflate_bytes(&input).expect("deflation failed");
-            let out = inflate_bytes(&cmp).expect("inflation failed");
+            let cmp = deflate_bytes(&input);
+            let out = inflate_bytes(&cmp).unwrap();
             debug!("{} bytes deflated to {} ({:.1}% size)",
                    input.len(), cmp.len(),
                    100.0 * ((cmp.len() as f64) / (input.len() as f64)));
@@ -164,9 +184,9 @@ mod tests {
 
     #[test]
     fn test_zlib_flate() {
-        let bytes = vec!(1, 2, 3, 4, 5);
-        let deflated = deflate_bytes(&bytes).expect("deflation failed");
-        let inflated = inflate_bytes(&deflated).expect("inflation failed");
+        let bytes = vec![1, 2, 3, 4, 5];
+        let deflated = deflate_bytes(&bytes);
+        let inflated = inflate_bytes(&deflated).unwrap();
         assert_eq!(&*inflated, &*bytes);
     }
 }

src/librustc/metadata/loader.rs

@@ -784,8 +784,8 @@ fn get_metadata_section_imp(is_osx: bool, filename: &Path) -> Result<MetadataBlo
                        csz - vlen);
                 let bytes = slice::from_raw_parts(cvbuf1, csz - vlen);
                 match flate::inflate_bytes(bytes) {
-                    Some(inflated) => return Ok(MetadataVec(inflated)),
-                    None => {}
+                    Ok(inflated) => return Ok(MetadataVec(inflated)),
+                    Err(_) => {}
                 }
             }
             llvm::LLVMMoveToNextSection(si.llsi);

src/librustc_trans/back/link.rs

@@ -626,12 +626,7 @@ fn link_rlib<'a>(sess: &'a Session,
                                                  e))
                 }
 
-                let bc_data_deflated = match flate::deflate_bytes(&bc_data[..]) {
-                    Some(compressed) => compressed,
-                    None => sess.fatal(&format!("failed to compress bytecode \
-                                                 from {}",
-                                                 bc_filename.display()))
-                };
+                let bc_data_deflated = flate::deflate_bytes(&bc_data[..]);
 
                 let mut bc_file_deflated = match fs::File::create(&bc_deflated_filename) {
                     Ok(file) => file,

src/librustc_trans/back/lto.rs

@@ -96,8 +96,8 @@ pub fn run(sess: &session::Session, llmod: ModuleRef,
                             (link::RLIB_BYTECODE_OBJECT_V1_DATA_OFFSET + data_size as uint)];
 
                         match flate::inflate_bytes(compressed_data) {
-                            Some(inflated) => inflated,
-                            None => {
+                            Ok(inflated) => inflated,
+                            Err(_) => {
                                 sess.fatal(&format!("failed to decompress bc of `{}`",
                                                    name))
                             }
@@ -112,8 +112,8 @@ pub fn run(sess: &session::Session, llmod: ModuleRef,
                 // the object must be in the old, pre-versioning format, so simply
                 // inflate everything and let LLVM decide if it can make sense of it
                     match flate::inflate_bytes(bc_encoded) {
-                        Some(bc) => bc,
-                        None => {
+                        Ok(bc) => bc,
+                        Err(_) => {
                             sess.fatal(&format!("failed to decompress bc of `{}`",
                                                name))
                         }

src/librustc_trans/trans/base.rs

@@ -2974,10 +2974,7 @@ pub fn write_metadata(cx: &SharedCrateContext, krate: &ast::Crate) -> Vec<u8> {
     let encode_parms = crate_ctxt_to_encode_parms(cx, encode_inlined_item);
     let metadata = encoder::encode_metadata(encode_parms, krate);
     let mut compressed = encoder::metadata_encoding_version.to_vec();
-    compressed.push_all(&match flate::deflate_bytes(&metadata) {
-        Some(compressed) => compressed,
-        None => cx.sess().fatal("failed to compress metadata"),
-    });
+    compressed.push_all(&flate::deflate_bytes(&metadata));
     let llmeta = C_bytes_in_context(cx.metadata_llcx(), &compressed[..]);
     let llconst = C_struct_in_context(cx.metadata_llcx(), &[llmeta], false);
     let name = format!("rust_metadata_{}_{}",