dd: allow B as a suffix for count, seek, and skip

Allow uppercase "B" on its own as a unit specifier for the `count`,
`seek`, and `skip` arguments to `dd`.

For example,

    $ printf "abcdef" | dd count=3B status=none
    abc

src/uu/dd/src/parseargs.rs

@@ -14,7 +14,7 @@ use crate::conversion_tables::ConversionTable;
 use std::error::Error;
 use uucore::display::Quotable;
 use uucore::error::UError;
-use uucore::parse_size::ParseSizeError;
+use uucore::parse_size::{ParseSizeError, Parser as SizeParser};
 use uucore::show_warning;
 
 /// Parser Errors describe errors with parser input
@@ -499,8 +499,11 @@ fn parse_bytes_only(s: &str) -> Result<u64, ParseError> {
 /// assert_eq!(parse_bytes_no_x("2k", "2k").unwrap(), 2 * 1024);
 /// ```
 fn parse_bytes_no_x(full: &str, s: &str) -> Result<u64, ParseError> {
+    let parser = SizeParser {
+        capital_b_bytes: true,
+    };
     let (num, multiplier) = match (s.find('c'), s.rfind('w'), s.rfind('b')) {
-        (None, None, None) => match uucore::parse_size::parse_size(s) {
+        (None, None, None) => match parser.parse(s) {
             Ok(n) => (n, 1),
             Err(ParseSizeError::InvalidSuffix(_)) | Err(ParseSizeError::ParseFailure(_)) => {
                 return Err(ParseError::InvalidNumber(full.to_string()))

src/uucore/src/lib/parser/parse_size.rs

@@ -15,6 +15,8 @@ use crate::display::Quotable;
 /// The [`Parser::parse`] function performs the parse.
 #[derive(Default)]
 pub struct Parser {
+    /// Whether to treat the suffix "B" as meaning "bytes".
+    pub capital_b_bytes: bool,
 }
 
 impl Parser {
@@ -67,6 +69,7 @@ impl Parser {
         let unit = &size[numeric_string.len()..];
         let (base, exponent): (u128, u32) = match unit {
             "" => (1, 0),
+            "B" if self.capital_b_bytes => (1, 0),
             "b" => (512, 1),
             "KiB" | "kiB" | "K" | "k" => (1024, 1),
             "MiB" | "miB" | "M" | "m" => (1024, 2),

tests/by-util/test_dd.rs

@@ -1295,3 +1295,33 @@ fn test_big_multiplication() {
         .fails()
         .stderr_contains("invalid number");
 }
+
+/// Test for count, seek, and skip given in units of bytes.
+#[test]
+fn test_bytes_suffix() {
+    new_ucmd!()
+        .args(&["count=3B", "status=none"])
+        .pipe_in("abcdef")
+        .succeeds()
+        .stdout_only("abc");
+    new_ucmd!()
+        .args(&["skip=3B", "status=none"])
+        .pipe_in("abcdef")
+        .succeeds()
+        .stdout_only("def");
+    new_ucmd!()
+        .args(&["iseek=3B", "status=none"])
+        .pipe_in("abcdef")
+        .succeeds()
+        .stdout_only("def");
+    new_ucmd!()
+        .args(&["seek=3B", "status=none"])
+        .pipe_in("abcdef")
+        .succeeds()
+        .stdout_only("\0\0\0abcdef");
+    new_ucmd!()
+        .args(&["oseek=3B", "status=none"])
+        .pipe_in("abcdef")
+        .succeeds()
+        .stdout_only("\0\0\0abcdef");
+}