Use fs helpers instead of File functions.

crates/cargo-test-support/src/git.rs

@@ -39,8 +39,7 @@ use some of the helper functions in this file to interact with the repository.
 */
 
 use crate::{path2url, project, Project, ProjectBuilder};
-use std::fs::{self, File};
-use std::io::prelude::*;
+use std::fs;
 use std::path::{Path, PathBuf};
 use url::Url;
 
@@ -81,7 +80,7 @@ impl RepoBuilder {
     pub fn nocommit_file(self, path: &str, contents: &str) -> RepoBuilder {
         let dst = self.repo.workdir().unwrap().join(path);
         t!(fs::create_dir_all(dst.parent().unwrap()));
-        t!(t!(File::create(&dst)).write_all(contents.as_bytes()));
+        t!(fs::write(&dst, contents));
         self
     }
 

crates/cargo-test-support/src/lib.rs

@@ -112,7 +112,6 @@ use std::env;
 use std::ffi::OsStr;
 use std::fmt;
 use std::fs;
-use std::io::prelude::*;
 use std::os;
 use std::path::{Path, PathBuf};
 use std::process::{Command, Output};
@@ -166,11 +165,8 @@ impl FileBuilder {
 
     fn mk(&self) {
         self.dirname().mkdir_p();
-
-        let mut file = fs::File::create(&self.path)
+        fs::write(&self.path, &self.body)
             .unwrap_or_else(|e| panic!("could not create file {}: {}", self.path.display(), e));
-
-        t!(file.write_all(self.body.as_bytes()));
     }
 
     fn dirname(&self) -> &Path {
@@ -458,25 +454,15 @@ impl Project {
 
     /// Returns the contents of a path in the project root
     pub fn read_file(&self, path: &str) -> String {
-        let mut buffer = String::new();
-        fs::File::open(self.root().join(path))
-            .unwrap()
-            .read_to_string(&mut buffer)
-            .unwrap();
-        buffer
+        let full = self.root().join(path);
+        fs::read_to_string(&full)
+            .unwrap_or_else(|e| panic!("could not read file {}: {}", full.display(), e))
     }
 
     /// Modifies `Cargo.toml` to remove all commented lines.
     pub fn uncomment_root_manifest(&self) {
-        let mut contents = String::new();
-        fs::File::open(self.root().join("Cargo.toml"))
-            .unwrap()
-            .read_to_string(&mut contents)
-            .unwrap();
-        fs::File::create(self.root().join("Cargo.toml"))
-            .unwrap()
-            .write_all(contents.replace("#", "").as_bytes())
-            .unwrap();
+        let contents = self.read_file("Cargo.toml").replace("#", "");
+        fs::write(self.root().join("Cargo.toml"), contents).unwrap();
     }
 
     pub fn symlink(&self, src: impl AsRef<Path>, dst: impl AsRef<Path>) {

crates/cargo-test-support/src/registry.rs

@@ -165,33 +165,34 @@ pub fn init() {
     if config.exists() {
         return;
     }
-    t!(t!(File::create(&config)).write_all(
+    t!(fs::write(
+        &config,
         format!(
             r#"
-        [source.crates-io]
-        registry = 'https://wut'
-        replace-with = 'dummy-registry'
+                [source.crates-io]
+                registry = 'https://wut'
+                replace-with = 'dummy-registry'
 
-        [source.dummy-registry]
-        registry = '{reg}'
+                [source.dummy-registry]
+                registry = '{reg}'
 
-        [registries.alternative]
-        index = '{alt}'
-    "#,
+                [registries.alternative]
+                index = '{alt}'
+            "#,
             reg = registry_url(),
             alt = alt_registry_url()
         )
-        .as_bytes()
     ));
     let credentials = paths::home().join(".cargo/credentials");
-    t!(t!(File::create(&credentials)).write_all(
-        br#"
-        [registry]
-        token = "api-token"
-
-        [registries.alternative]
-        token = "api-token"
-    "#
+    t!(fs::write(
+        &credentials,
+        r#"
+            [registry]
+            token = "api-token"
+
+            [registries.alternative]
+            token = "api-token"
+        "#
     ));
 
     // Initialize a new registry.
@@ -404,8 +405,7 @@ impl Package {
             })
             .collect::<Vec<_>>();
         let cksum = {
-            let mut c = Vec::new();
-            t!(t!(File::open(&self.archive_dst())).read_to_end(&mut c));
+            let c = t!(fs::read(&self.archive_dst()));
             cksum(&c)
         };
         let name = if self.invalid_json {
@@ -442,10 +442,9 @@ impl Package {
         } else {
             registry_path.join(&file)
         };
-        let mut prev = String::new();
-        let _ = File::open(&dst).and_then(|mut f| f.read_to_string(&mut prev));
+        let prev = fs::read_to_string(&dst).unwrap_or(String::new());
         t!(fs::create_dir_all(dst.parent().unwrap()));
-        t!(t!(File::create(&dst)).write_all((prev + &line[..] + "\n").as_bytes()));
+        t!(fs::write(&dst, prev + &line[..] + "\n"));
 
         // Add the new file to the index.
         if !self.local {

src/cargo/ops/vendor.rs

@@ -8,8 +8,7 @@ use anyhow::bail;
 use serde::Serialize;
 use std::collections::HashSet;
 use std::collections::{BTreeMap, BTreeSet, HashMap};
-use std::fs::{self, File};
-use std::io::Write;
+use std::fs;
 use std::path::{Path, PathBuf};
 
 pub struct VendorOptions<'a> {
@@ -223,7 +222,7 @@ fn sync(
             "files": map,
         });
 
-        File::create(&cksum)?.write_all(json.to_string().as_bytes())?;
+        paths::write(&cksum, json.to_string())?;
     }
 
     for path in to_remove {

src/cargo/sources/registry/remote.rs

@@ -9,7 +9,7 @@ use lazycell::LazyCell;
 use log::{debug, trace};
 use std::cell::{Cell, Ref, RefCell};
 use std::fmt::Write as FmtWrite;
-use std::fs::{File, OpenOptions};
+use std::fs::{self, File, OpenOptions};
 use std::io::prelude::*;
 use std::io::SeekFrom;
 use std::mem;
@@ -300,10 +300,8 @@ impl<'cfg> RegistryData for RemoteRegistry<'cfg> {
 
         let path = self.cache_path.join(path);
         let path = self.config.assert_package_cache_locked(&path);
-        if let Ok(dst) = File::open(path) {
-            if let Ok(meta) = dst.metadata() {
-                return meta.len() > 0;
-            }
+        if let Ok(meta) = fs::metadata(path) {
+            return meta.len() > 0;
         }
         false
     }

src/cargo/util/cpu.rs

@@ -26,8 +26,7 @@ impl State {
 
 #[cfg(target_os = "linux")]
 mod imp {
-    use std::fs::File;
-    use std::io::{self, Read};
+    use std::{fs, io};
 
     pub struct State {
         user: u64,
@@ -43,8 +42,7 @@ mod imp {
     }
 
     pub fn current() -> io::Result<State> {
-        let mut state = String::new();
-        File::open("/proc/stat")?.read_to_string(&mut state)?;
+        let state = fs::read_to_string("/proc/stat")?;
 
         (|| {
             let mut parts = state.lines().next()?.split_whitespace();

src/cargo/util/paths.rs

@@ -1,6 +1,6 @@
 use std::env;
 use std::ffi::{OsStr, OsString};
-use std::fs::{self, File, OpenOptions};
+use std::fs::{self, OpenOptions};
 use std::io;
 use std::io::prelude::*;
 use std::iter;
@@ -118,27 +118,12 @@ pub fn read(path: &Path) -> CargoResult<String> {
 }
 
 pub fn read_bytes(path: &Path) -> CargoResult<Vec<u8>> {
-    let res = (|| -> CargoResult<_> {
-        let mut ret = Vec::new();
-        let mut f = File::open(path)?;
-        if let Ok(m) = f.metadata() {
-            ret.reserve(m.len() as usize + 1);
-        }
-        f.read_to_end(&mut ret)?;
-        Ok(ret)
-    })()
-    .chain_err(|| format!("failed to read `{}`", path.display()))?;
-    Ok(res)
+    fs::read(path).chain_err(|| format!("failed to read `{}`", path.display()))
 }
 
-pub fn write(path: &Path, contents: &[u8]) -> CargoResult<()> {
-    (|| -> CargoResult<()> {
-        let mut f = File::create(path)?;
-        f.write_all(contents)?;
-        Ok(())
-    })()
-    .chain_err(|| format!("failed to write `{}`", path.display()))?;
-    Ok(())
+pub fn write<P: AsRef<Path>, C: AsRef<[u8]>>(path: P, contents: C) -> CargoResult<()> {
+    let path = path.as_ref();
+    fs::write(path, contents.as_ref()).chain_err(|| format!("failed to write `{}`", path.display()))
 }
 
 pub fn write_if_changed<P: AsRef<Path>, C: AsRef<[u8]>>(path: P, contents: C) -> CargoResult<()> {
@@ -190,7 +175,7 @@ pub fn set_invocation_time(path: &Path) -> CargoResult<FileTime> {
     let timestamp = path.join("invoked.timestamp");
     write(
         &timestamp,
-        b"This file has an mtime of when this was started.",
+        "This file has an mtime of when this was started.",
     )?;
     let ft = mtime(&timestamp)?;
     log::debug!("invocation time for {:?} is {}", path, ft);

tests/testsuite/alt_registry.rs

@@ -4,8 +4,7 @@ use cargo::util::IntoUrl;
 use cargo_test_support::publish::validate_alt_upload;
 use cargo_test_support::registry::{self, Package};
 use cargo_test_support::{basic_manifest, git, paths, project};
-use std::fs::{self, File};
-use std::io::Write;
+use std::fs;
 
 #[cargo_test]
 fn depend_on_alt_registry() {
@@ -534,16 +533,14 @@ fn passwords_in_registry_index_url_forbidden() {
     registry::init();
 
     let config = paths::home().join(".cargo/config");
-
-    File::create(config)
-        .unwrap()
-        .write_all(
-            br#"
+    fs::write(
+        config,
+        r#"
         [registry]
         index = "ssh://git:secret@foobar.com"
         "#,
-        )
-        .unwrap();
+    )
+    .unwrap();
 
     let p = project().file("src/main.rs", "fn main() {}").build();
 
@@ -559,15 +556,14 @@ fn passwords_in_registries_index_url_forbidden() {
 
     let config = paths::home().join(".cargo/config");
 
-    File::create(config)
-        .unwrap()
-        .write_all(
-            br#"
+    fs::write(
+        config,
+        r#"
         [registries.alternative]
         index = "ssh://git:secret@foobar.com"
         "#,
-        )
-        .unwrap();
+    )
+    .unwrap();
 
     let p = project().file("src/main.rs", "fn main() {}").build();
 
@@ -1181,15 +1177,14 @@ fn unknown_registry() {
 fn registries_index_relative_url() {
     let config = paths::root().join(".cargo/config");
     fs::create_dir_all(config.parent().unwrap()).unwrap();
-    File::create(&config)
-        .unwrap()
-        .write_all(
-            br#"
+    fs::write(
+        &config,
+        r#"
             [registries.relative]
             index = "file:alternative-registry"
         "#,
-        )
-        .unwrap();
+    )
+    .unwrap();
 
     registry::init();
 
@@ -1231,15 +1226,14 @@ fn registries_index_relative_url() {
 fn registry_index_relative_url() {
     let config = paths::root().join(".cargo/config");
     fs::create_dir_all(config.parent().unwrap()).unwrap();
-    File::create(&config)
-        .unwrap()
-        .write_all(
-            br#"
+    fs::write(
+        &config,
+        r#"
             [registry]
             index = "file:alternative-registry"
         "#,
-        )
-        .unwrap();
+    )
+    .unwrap();
 
     registry::init();
 
@@ -1283,15 +1277,14 @@ warning: custom registry support via the `registry.index` configuration is being
 fn registries_index_relative_path_not_allowed() {
     let config = paths::root().join(".cargo/config");
     fs::create_dir_all(config.parent().unwrap()).unwrap();
-    File::create(&config)
-        .unwrap()
-        .write_all(
-            br#"
+    fs::write(
+        &config,
+        r#"
             [registries.relative]
             index = "alternative-registry"
         "#,
-        )
-        .unwrap();
+    )
+    .unwrap();
 
     registry::init();