pr: Set date format depending on environment.

Based on GNU manual.

src/uu/pr/src/pr.rs

@@ -20,7 +20,7 @@ use uucore::display::Quotable;
 use uucore::error::UResult;
 use uucore::format_usage;
 use uucore::translate;
-use uucore::time::{FormatSystemTimeFallback, format_system_time};
+use uucore::time::{FormatSystemTimeFallback, format, format_system_time};
 
 const TAB: char = '\t';
 const LINES_PER_PAGE: usize = 66;
@@ -33,7 +33,6 @@ const DEFAULT_COLUMN_WIDTH: usize = 72;
 const DEFAULT_COLUMN_WIDTH_WITH_S_OPTION: usize = 512;
 const DEFAULT_COLUMN_SEPARATOR: &char = &TAB;
 const FF: u8 = 0x0C_u8;
-const DATE_TIME_FORMAT: &str = "%b %d %H:%M %Y";
 
 mod options {
     pub const HEADER: &str = "header";
@@ -402,6 +401,20 @@ fn parse_usize(matches: &ArgMatches, opt: &str) -> Option<Result<usize, PrError>
         .map(from_parse_error_to_pr_error)
 }
 
+fn get_date_format() -> String {
+    // Replicate behavior from GNU manual.
+    if std::env::var("POSIXLY_CORRECT").is_ok()
+        // TODO: This needs to be moved to uucore and handled by icu?
+        && (std::env::var("LC_TIME").unwrap_or_default() == "POSIX"
+            || std::env::var("LC_ALL").unwrap_or_default() == "POSIX")
+    {
+        "%b %e %H:%M %Y"
+    } else {
+        format::LONG_ISO
+    }
+    .to_string()
+}
+
 #[allow(clippy::cognitive_complexity)]
 fn build_options(
     matches: &ArgMatches,
@@ -501,7 +514,7 @@ fn build_options(
             format_system_time(
                 &mut v,
                 time,
-                DATE_TIME_FORMAT,
+                &get_date_format(),
                 FormatSystemTimeFallback::Integer,
             )
             .ok()

tests/by-util/test_pr.rs

@@ -9,9 +9,9 @@ use std::fs::metadata;
 use uutests::new_ucmd;
 use uutests::util::UCommand;
 
-const DATE_TIME_FORMAT: &str = "%b %d %H:%M %Y";
+const DATE_TIME_FORMAT_DEFAULT: &str = "%Y-%m-%d %H:%M";
 
-fn file_last_modified_time(ucmd: &UCommand, path: &str) -> String {
+fn file_last_modified_time_format(ucmd: &UCommand, path: &str, format: &str) -> String {
     let tmp_dir_path = ucmd.get_full_fixture_path(path);
     let file_metadata = metadata(tmp_dir_path);
     file_metadata
@@ -19,19 +19,23 @@ fn file_last_modified_time(ucmd: &UCommand, path: &str) -> String {
             i.modified()
                 .map(|x| {
                     let date_time: DateTime<Utc> = x.into();
-                    date_time.format(DATE_TIME_FORMAT).to_string()
+                    date_time.format(format).to_string()
                 })
                 .unwrap_or_default()
         })
         .unwrap_or_default()
 }
 
+fn file_last_modified_time(ucmd: &UCommand, path: &str) -> String {
+    file_last_modified_time_format(ucmd, path, DATE_TIME_FORMAT_DEFAULT)
+}
+
 fn all_minutes(from: DateTime<Utc>, to: DateTime<Utc>) -> Vec<String> {
     let to = to + Duration::try_minutes(1).unwrap();
     let mut vec = vec![];
     let mut current = from;
     while current < to {
-        vec.push(current.format(DATE_TIME_FORMAT).to_string());
+        vec.push(current.format(DATE_TIME_FORMAT_DEFAULT).to_string());
         current += Duration::try_minutes(1).unwrap();
     }
     vec
@@ -398,6 +402,50 @@ fn test_with_offset_space_option() {
         .stdout_is_templated_fixture(expected_test_file_path, &[("{last_modified_time}", &value)]);
 }
 
+#[test]
+fn test_with_date_format() {
+    const POSIXLY_FORMAT: &str = "%b %e %H:%M %Y";
+
+    // POSIXLY_CORRECT + LC_ALL/TIME=POSIX uses "%b %e %H:%M %Y" date format
+    let test_file_path = "test_one_page.log";
+    let expected_test_file_path = "test_one_page.log.expected";
+    let mut scenario = new_ucmd!();
+    let value = file_last_modified_time_format(&scenario, test_file_path, POSIXLY_FORMAT);
+    scenario
+        .env("POSIXLY_CORRECT", "1")
+        .env("LC_ALL", "POSIX")
+        .args(&[test_file_path])
+        .succeeds()
+        .stdout_is_templated_fixture(expected_test_file_path, &[("{last_modified_time}", &value)]);
+
+    let mut scenario = new_ucmd!();
+    let value = file_last_modified_time_format(&scenario, test_file_path, POSIXLY_FORMAT);
+    scenario
+        .env("POSIXLY_CORRECT", "1")
+        .env("LC_TIME", "POSIX")
+        .args(&[test_file_path])
+        .succeeds()
+        .stdout_is_templated_fixture(expected_test_file_path, &[("{last_modified_time}", &value)]);
+
+    // But not if POSIXLY_CORRECT/LC_ALL is something else.
+    let mut scenario = new_ucmd!();
+    let value = file_last_modified_time_format(&scenario, test_file_path, DATE_TIME_FORMAT_DEFAULT);
+    scenario
+        .env("LC_TIME", "POSIX")
+        .args(&[test_file_path])
+        .succeeds()
+        .stdout_is_templated_fixture(expected_test_file_path, &[("{last_modified_time}", &value)]);
+
+    let mut scenario = new_ucmd!();
+    let value = file_last_modified_time_format(&scenario, test_file_path, DATE_TIME_FORMAT_DEFAULT);
+    scenario
+        .env("POSIXLY_CORRECT", "1")
+        .env("LC_TIME", "C")
+        .args(&[test_file_path])
+        .succeeds()
+        .stdout_is_templated_fixture(expected_test_file_path, &[("{last_modified_time}", &value)]);
+}
+
 #[test]
 fn test_with_pr_core_utils_tests() {
     let test_cases = vec![