Rollup merge of rust-lang#47328 - mbrubeck:fs_read, r=sfackler

Use the new fs_read_write functions in rustc internals

Uses `fs::read` and `fs::write` (added by rust-lang#45837) where appropriate, to simplify code and dog-food these new APIs.  This also improves performance, when combined with rust-lang#47324.

src/librustc/lib.rs

@@ -48,6 +48,7 @@
 #![feature(drain_filter)]
 #![feature(dyn_trait)]
 #![feature(from_ref)]
+#![feature(fs_read_write)]
 #![feature(i128)]
 #![feature(i128_type)]
 #![feature(inclusive_range)]

src/librustc/util/common.rs

@@ -218,13 +218,10 @@ pub fn record_time<T, F>(accu: &Cell<Duration>, f: F) -> T where
 // Memory reporting
 #[cfg(unix)]
 fn get_resident() -> Option<usize> {
-    use std::fs::File;
-    use std::io::Read;
+    use std::fs;
 
     let field = 1;
-    let mut f = File::open("/proc/self/statm").ok()?;
-    let mut contents = String::new();
-    f.read_to_string(&mut contents).ok()?;
+    let contents = fs::read_string("/proc/self/statm").ok()?;
     let s = contents.split_whitespace().nth(field)?;
     let npages = s.parse::<usize>().ok()?;
     Some(npages * 4096)

src/librustc_back/lib.rs

@@ -28,6 +28,7 @@
 
 #![feature(box_syntax)]
 #![feature(const_fn)]
+#![feature(fs_read_write)]
 
 extern crate syntax;
 extern crate rand;

src/librustc_back/target/mod.rs

@@ -47,7 +47,6 @@
 use serialize::json::{Json, ToJson};
 use std::collections::BTreeMap;
 use std::default::Default;
-use std::io::prelude::*;
 use syntax::abi::{Abi, lookup as lookup_abi};
 
 use {LinkerFlavor, PanicStrategy, RelroLevel};
@@ -809,14 +808,12 @@ impl Target {
     pub fn search(target: &str) -> Result<Target, String> {
         use std::env;
         use std::ffi::OsString;
-        use std::fs::File;
+        use std::fs;
         use std::path::{Path, PathBuf};
         use serialize::json;
 
         fn load_file(path: &Path) -> Result<Target, String> {
-            let mut f = File::open(path).map_err(|e| e.to_string())?;
-            let mut contents = Vec::new();
-            f.read_to_end(&mut contents).map_err(|e| e.to_string())?;
+            let contents = fs::read(path).map_err(|e| e.to_string())?;
             let obj = json::from_reader(&mut &contents[..])
                            .map_err(|e| e.to_string())?;
             Target::from_json(obj)

src/librustc_incremental/assert_dep_graph.rs

@@ -55,7 +55,7 @@ use rustc::hir::intravisit::{self, NestedVisitorMap, Visitor};
 use rustc::ich::{ATTR_IF_THIS_CHANGED, ATTR_THEN_THIS_WOULD_NEED};
 use graphviz::IntoCow;
 use std::env;
-use std::fs::File;
+use std::fs::{self, File};
 use std::io::Write;
 use syntax::ast;
 use syntax_pos::Span;
@@ -260,7 +260,7 @@ fn dump_graph(tcx: TyCtxt) {
         let dot_path = format!("{}.dot", path);
         let mut v = Vec::new();
         dot::render(&GraphvizDepGraph(nodes, edges), &mut v).unwrap();
-        File::create(&dot_path).and_then(|mut f| f.write_all(&v)).unwrap();
+        fs::write(dot_path, v).unwrap();
     }
 }
 

src/librustc_incremental/lib.rs

@@ -16,6 +16,7 @@
 #![deny(warnings)]
 
 #![feature(conservative_impl_trait)]
+#![feature(fs_read_write)]
 #![feature(i128_type)]
 #![feature(inclusive_range_syntax)]
 #![feature(specialization)]

src/librustc_incremental/persist/file_format.rs

@@ -21,7 +21,7 @@
 
 use std::io::{self, Read};
 use std::path::Path;
-use std::fs::File;
+use std::fs;
 use std::env;
 
 use rustc::session::config::nightly_options;
@@ -66,11 +66,7 @@ pub fn read_file(report_incremental_info: bool, path: &Path)
         return Ok(None);
     }
 
-    let mut file = File::open(path)?;
-    let file_size = file.metadata()?.len() as usize;
-
-    let mut data = Vec::with_capacity(file_size);
-    file.read_to_end(&mut data)?;
+    let data = fs::read(path)?;
 
     let mut file = io::Cursor::new(data);
 

src/librustc_incremental/persist/save.rs

@@ -15,8 +15,8 @@ use rustc::util::common::time;
 use rustc_data_structures::fx::FxHashMap;
 use rustc_serialize::Encodable as RustcEncodable;
 use rustc_serialize::opaque::Encoder;
-use std::io::{self, Cursor, Write};
-use std::fs::{self, File};
+use std::io::{self, Cursor};
+use std::fs;
 use std::path::PathBuf;
 
 use super::data::*;
@@ -125,7 +125,7 @@ fn save_in<F>(sess: &Session, path_buf: PathBuf, encode: F)
 
     // write the data out
     let data = wr.into_inner();
-    match File::create(&path_buf).and_then(|mut file| file.write_all(&data)) {
+    match fs::write(&path_buf, data) {
         Ok(_) => {
             debug!("save: data written to disk successfully");
         }

src/librustc_metadata/lib.rs

@@ -15,6 +15,7 @@
 
 #![feature(box_patterns)]
 #![feature(conservative_impl_trait)]
+#![feature(fs_read_write)]
 #![feature(i128_type)]
 #![feature(libc)]
 #![feature(proc_macro_internals)]

src/librustc_metadata/locator.rs

@@ -237,7 +237,7 @@ use rustc_back::target::Target;
 
 use std::cmp;
 use std::fmt;
-use std::fs::{self, File};
+use std::fs;
 use std::io::{self, Read};
 use std::path::{Path, PathBuf};
 use std::time::Instant;
@@ -870,10 +870,7 @@ fn get_metadata_section_imp(target: &Target,
             }
         }
         CrateFlavor::Rmeta => {
-            let mut file = File::open(filename).map_err(|_|
-                format!("could not open file: '{}'", filename.display()))?;
-            let mut buf = vec![];
-            file.read_to_end(&mut buf).map_err(|_|
+            let buf = fs::read(filename).map_err(|_|
                 format!("failed to read rmeta metadata: '{}'", filename.display()))?;
             OwningRef::new(buf).map_owner_box().erase_owner()
         }

src/librustc_mir/dataflow/graphviz.rs

@@ -18,7 +18,7 @@ use rustc_data_structures::indexed_vec::Idx;
 use dot;
 use dot::IntoCow;
 
-use std::fs::File;
+use std::fs;
 use std::io;
 use std::io::prelude::*;
 use std::marker::PhantomData;
@@ -67,7 +67,7 @@ pub(crate) fn print_borrowck_graph_to<'a, 'tcx, BD, P>(
     dot::render(&g, &mut v)?;
     debug!("print_borrowck_graph_to path: {} node_id: {}",
            path.display(), mbcx.node_id);
-    File::create(path).and_then(|mut f| f.write_all(&v))
+    fs::write(path, v)
 }
 
 pub type Node = BasicBlock;

src/librustc_mir/lib.rs

@@ -24,6 +24,7 @@ Rust MIR: a lowered representation of Rust. Also: an experiment!
 #![feature(core_intrinsics)]
 #![feature(decl_macro)]
 #![feature(dyn_trait)]
+#![feature(fs_read_write)]
 #![feature(i128_type)]
 #![feature(inclusive_range_syntax)]
 #![feature(inclusive_range)]

src/librustc_trans/back/link.rs

@@ -342,9 +342,7 @@ fn archive_config<'a>(sess: &'a Session,
 fn emit_metadata<'a>(sess: &'a Session, trans: &CrateTranslation, tmpdir: &TempDir)
                      -> PathBuf {
     let out_filename = tmpdir.path().join(METADATA_FILENAME);
-    let result = fs::File::create(&out_filename).and_then(|mut f| {
-        f.write_all(&trans.metadata.raw_data)
-    });
+    let result = fs::write(&out_filename, &trans.metadata.raw_data);
 
     if let Err(e) = result {
         sess.fatal(&format!("failed to write {}: {}", out_filename.display(), e));

src/librustc_trans/back/write.rs

@@ -46,9 +46,8 @@ use rustc_demangle;
 
 use std::any::Any;
 use std::ffi::{CString, CStr};
-use std::fs::{self, File};
-use std::io;
-use std::io::{Read, Write};
+use std::fs;
+use std::io::{self, Write};
 use std::mem;
 use std::path::{Path, PathBuf};
 use std::str;
@@ -666,7 +665,7 @@ unsafe fn codegen(cgcx: &CodegenContext,
         timeline.record("make-bc");
 
         if write_bc {
-            if let Err(e) = File::create(&bc_out).and_then(|mut f| f.write_all(data)) {
+            if let Err(e) = fs::write(&bc_out, data) {
                 diag_handler.err(&format!("failed to write bytecode: {}", e));
             }
             timeline.record("write-bc");
@@ -675,7 +674,7 @@ unsafe fn codegen(cgcx: &CodegenContext,
         if config.emit_bc_compressed {
             let dst = bc_out.with_extension(RLIB_BYTECODE_EXTENSION);
             let data = bytecode::encode(&mtrans.llmod_id, data);
-            if let Err(e) = File::create(&dst).and_then(|mut f| f.write_all(&data)) {
+            if let Err(e) = fs::write(&dst, data) {
                 diag_handler.err(&format!("failed to write bytecode: {}", e));
             }
             timeline.record("compress-bc");
@@ -799,9 +798,7 @@ fn binaryen_assemble(cgcx: &CodegenContext,
                      object: &Path) {
     use rustc_binaryen::{Module, ModuleOptions};
 
-    let input = File::open(&assembly).and_then(|mut f| {
-        let mut contents = Vec::new();
-        f.read_to_end(&mut contents)?;
+    let input = fs::read(&assembly).and_then(|contents| {
         Ok(CString::new(contents)?)
     });
     let mut options = ModuleOptions::new();
@@ -818,7 +815,7 @@ fn binaryen_assemble(cgcx: &CodegenContext,
             .map_err(|e| io::Error::new(io::ErrorKind::Other, e))
     });
     let err = assembled.and_then(|binary| {
-        File::create(&object).and_then(|mut f| f.write_all(binary.data()))
+        fs::write(&object, binary.data())
     });
     if let Err(e) = err {
         handler.err(&format!("failed to run binaryen assembler: {}", e));

src/librustc_trans/lib.rs

@@ -22,6 +22,7 @@
 #![feature(box_patterns)]
 #![feature(box_syntax)]
 #![feature(custom_attribute)]
+#![feature(fs_read_write)]
 #![allow(unused_attributes)]
 #![feature(i128_type)]
 #![feature(i128)]

src/librustdoc/externalfiles.rs

@@ -8,8 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use std::fs::File;
-use std::io::prelude::*;
+use std::fs;
 use std::path::Path;
 use std::str;
 use html::markdown::{Markdown, RenderType};
@@ -65,13 +64,13 @@ pub enum LoadStringError {
 
 pub fn load_string<P: AsRef<Path>>(file_path: P) -> Result<String, LoadStringError> {
     let file_path = file_path.as_ref();
-    let mut contents = vec![];
-    let result = File::open(file_path)
-                      .and_then(|mut f| f.read_to_end(&mut contents));
-    if let Err(e) = result {
-        eprintln!("error reading `{}`: {}", file_path.display(), e);
-        return Err(LoadStringError::ReadFail);
-    }
+    let contents = match fs::read(file_path) {
+        Ok(bytes) => bytes,
+        Err(e) => {
+            eprintln!("error reading `{}`: {}", file_path.display(), e);
+            return Err(LoadStringError::ReadFail);
+        }
+    };
     match str::from_utf8(&contents) {
         Ok(s) => Ok(s.to_string()),
         Err(_) => {

src/librustdoc/html/render.rs

@@ -866,15 +866,8 @@ fn write_shared(cx: &Context,
     write(cx.dst.join("main.css"),
           include_bytes!("static/styles/main.css"))?;
     if let Some(ref css) = cx.shared.css_file_extension {
-        let mut content = String::new();
-        let css = css.as_path();
-        let mut f = try_err!(File::open(css), css);
-
-        try_err!(f.read_to_string(&mut content), css);
-        let css = cx.dst.join("theme.css");
-        let css = css.as_path();
-        let mut f = try_err!(File::create(css), css);
-        try_err!(write!(f, "{}", &content), css);
+        let out = cx.dst.join("theme.css");
+        try_err!(fs::copy(css, out), css);
     }
     write(cx.dst.join("normalize.css"),
           include_bytes!("static/normalize.css"))?;
@@ -1027,7 +1020,7 @@ fn render_sources(dst: &Path, scx: &mut SharedContext,
 /// Writes the entire contents of a string to a destination, not attempting to
 /// catch any errors.
 fn write(dst: PathBuf, contents: &[u8]) -> Result<(), Error> {
-    Ok(try_err!(try_err!(File::create(&dst), &dst).write_all(contents), &dst))
+    Ok(try_err!(fs::write(&dst, contents), &dst))
 }
 
 /// Takes a path to a source file and cleans the path to it. This canonicalizes
@@ -1124,16 +1117,13 @@ impl<'a> SourceCollector<'a> {
             return Ok(());
         }
 
-        let mut contents = Vec::new();
-        File::open(&p).and_then(|mut f| f.read_to_end(&mut contents))?;
-
-        let contents = str::from_utf8(&contents).unwrap();
+        let contents = fs::read_string(&p)?;
 
         // Remove the utf-8 BOM if any
         let contents = if contents.starts_with("\u{feff}") {
             &contents[3..]
         } else {
-            contents
+            &contents[..]
         };
 
         // Create the intermediate directories

src/librustdoc/lib.rs

@@ -18,6 +18,7 @@
 #![feature(rustc_private)]
 #![feature(box_patterns)]
 #![feature(box_syntax)]
+#![feature(fs_read_write)]
 #![feature(libc)]
 #![feature(set_stdio)]
 #![feature(slice_patterns)]