du: Add support for +FORMAT time-style

Also add to error text, which... GNU coreutils doesn't do for
some reason.

Author: drinkcat

src/uu/du/locales/en-US.ftl

@@ -52,6 +52,7 @@ du-error-invalid-time-style = invalid argument { $style } for 'time style'
     - 'full-iso'
     - 'long-iso'
     - 'iso'
+    - +FORMAT (e.g., +%H:%M) for a 'date'-style format
   Try '{ $help }' for more information.
 du-error-invalid-time-arg = 'birth' and 'creation' arguments for --time are not supported on this platform.
 du-error-invalid-glob = Invalid exclude syntax: { $error }

src/uu/du/locales/fr-FR.ftl

@@ -52,6 +52,7 @@ du-error-invalid-time-style = argument invalide { $style } pour 'style de temps'
     - 'full-iso'
     - 'long-iso'
     - 'iso'
+    - +FORMAT (e.g., +%H:%M) pour un format de type 'date'
   Essayez '{ $help }' pour plus d'informations.
 du-error-invalid-time-arg = les arguments 'birth' et 'creation' pour --time ne sont pas supportés sur cette plateforme.
 du-error-invalid-glob = Syntaxe d'exclusion invalide : { $error }

src/uu/du/src/du.rs

@@ -761,7 +761,10 @@ fn parse_time_style(s: Option<&str>) -> UResult<&str> {
             "full-iso" => Ok("%Y-%m-%d %H:%M:%S.%f %z"),
             "long-iso" => Ok("%Y-%m-%d %H:%M"),
             "iso" => Ok("%Y-%m-%d"),
-            _ => Err(DuError::InvalidTimeStyleArg(s.into()).into()),
+            _ => match s.chars().next().unwrap() {
+                '+' => Ok(&s[1..]),
+                _ => Err(DuError::InvalidTimeStyleArg(s.into()).into()),
+            },
         },
         None => Ok("%Y-%m-%d %H:%M"),
     }

tests/by-util/test_du.rs

@@ -626,6 +626,56 @@ fn test_du_time() {
         .succeeds();
     result.stdout_only("0\t2016-06-16 00:00\tdate_test\n");
 
+    // long-iso (same as default)
+    let result = ts
+        .ucmd()
+        .env("TZ", "UTC")
+        .arg("--time")
+        .arg("--time-style=long-iso")
+        .arg("date_test")
+        .succeeds();
+    result.stdout_only("0\t2016-06-16 00:00\tdate_test\n");
+
+    // full-iso
+    let result = ts
+        .ucmd()
+        .env("TZ", "UTC")
+        .arg("--time")
+        .arg("--time-style=full-iso")
+        .arg("date_test")
+        .succeeds();
+    result.stdout_only("0\t2016-06-16 00:00:00.000000000 +0000\tdate_test\n");
+
+    // iso
+    let result = ts
+        .ucmd()
+        .env("TZ", "UTC")
+        .arg("--time")
+        .arg("--time-style=iso")
+        .arg("date_test")
+        .succeeds();
+    result.stdout_only("0\t2016-06-16\tdate_test\n");
+
+    // custom +FORMAT
+    let result = ts
+        .ucmd()
+        .env("TZ", "UTC")
+        .arg("--time")
+        .arg("--time-style=+%Y__%H")
+        .arg("date_test")
+        .succeeds();
+    result.stdout_only("0\t2016__00\tdate_test\n");
+
+    // ls has special handling for new line in format, du doesn't.
+    let result = ts
+        .ucmd()
+        .env("TZ", "UTC")
+        .arg("--time")
+        .arg("--time-style=+%Y_\n_%H")
+        .arg("date_test")
+        .succeeds();
+    result.stdout_only("0\t2016_\n_00\tdate_test\n");
+
     for argument in ["--time=atime", "--time=atim", "--time=a"] {
         let result = ts
             .ucmd()