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dd: create Source enum and simpler Input struct

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This mirrors a recent commit that introduced the `Dest` enum and a
simplified `Output` struct. These changes allow us to add new types of
inputs and output more easily.
This commit is contained in:
Jeffrey Finkelstein 2022-11-12 15:44:32 -05:00 committed by Sylvestre Ledru
parent 3d3beb5437
commit cf72c990f2
1 changed files with 86 additions and 69 deletions
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155
src/uu/dd/src/dd.rs
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@ -27,7 +27,7 @@ use std::cmp;
use std::env;
use std::ffi::OsString;
use std::fs::{File, OpenOptions};
use std::io::{self, Read, Seek, SeekFrom, Stdout, Write};
use std::io::{self, Read, Seek, SeekFrom, Stdin, Stdout, Write};
#[cfg(any(target_os = "linux", target_os = "android"))]
use std::os::unix::fs::OpenOptionsExt;
use std::path::Path;
@ -90,30 +90,84 @@ impl Num {
}
}
struct Input<'a, R: Read> {
src: R,
/// Data sources.
enum Source {
/// Input from stdin.
Stdin(Stdin),
/// Input from a file.
File(File),
}
impl Source {
fn skip(&mut self, n: u64) -> io::Result<u64> {
match self {
Self::Stdin(stdin) => match io::copy(&mut stdin.take(n), &mut io::sink()) {
Ok(m) if m < n => {
show_error!("'standard input': cannot skip to specified offset");
Ok(m)
}
Ok(m) => Ok(m),
Err(e) => Err(e),
},
Self::File(f) => f.seek(io::SeekFrom::Start(n)),
}
}
}
impl Read for Source {
fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
match self {
Self::Stdin(stdin) => stdin.read(buf),
Self::File(f) => f.read(buf),
}
}
}
/// The source of the data, configured with the given settings.
///
/// Use the [`Input::new_stdin`] or [`Input::new_file`] functions to
/// construct a new instance of this struct. Then pass the instance to
/// the [`Output::dd_out`] function to execute the main copy operation
/// for `dd`.
struct Input<'a> {
/// The source from which bytes will be read.
src: Source,
/// Configuration settings for how to read the data.
settings: &'a Settings,
}
impl<'a> Input<'a, io::Stdin> {
fn new(settings: &'a Settings) -> UResult<Self> {
let mut input = Self {
src: io::stdin(),
settings,
impl<'a> Input<'a> {
/// Instantiate this struct with stdin as a source.
fn new_stdin(settings: &'a Settings) -> UResult<Self> {
let mut src = Source::Stdin(io::stdin());
if settings.skip > 0 {
src.skip(settings.skip)?;
}
Ok(Self { src, settings })
}
/// Instantiate this struct with the named file as a source.
fn new_file(filename: &Path, settings: &'a Settings) -> UResult<Self> {
let src = {
let mut opts = OpenOptions::new();
opts.read(true);
#[cfg(any(target_os = "linux", target_os = "android"))]
if let Some(libc_flags) = make_linux_iflags(&settings.iflags) {
opts.custom_flags(libc_flags);
}
opts.open(filename)
.map_err_context(|| format!("failed to open {}", filename.quote()))?
};
let mut src = Source::File(src);
if settings.skip > 0 {
if let Err(e) = input.read_skip(settings.skip) {
if let io::ErrorKind::UnexpectedEof = e.kind() {
show_error!("'standard input': cannot skip to specified offset");
} else {
return io::Result::Err(e)
.map_err_context(|| "I/O error while skipping".to_string());
}
}
src.skip(settings.skip)?;
}
Ok(input)
Ok(Self { src, settings })
}
}
@ -153,31 +207,7 @@ fn make_linux_iflags(iflags: &IFlags) -> Option<libc::c_int> {
}
}
impl<'a> Input<'a, File> {
fn new(filename: &Path, settings: &'a Settings) -> UResult<Self> {
let mut src = {
let mut opts = OpenOptions::new();
opts.read(true);
#[cfg(any(target_os = "linux", target_os = "android"))]
if let Some(libc_flags) = make_linux_iflags(&settings.iflags) {
opts.custom_flags(libc_flags);
}
opts.open(filename)
.map_err_context(|| format!("failed to open {}", filename.quote()))?
};
if settings.skip > 0 {
src.seek(io::SeekFrom::Start(settings.skip))
.map_err_context(|| "failed to seek in input file".to_string())?;
}
Ok(Self { src, settings })
}
}
impl<'a, R: Read> Read for Input<'a, R> {
impl<'a> Read for Input<'a> {
fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
let mut base_idx = 0;
let target_len = buf.len();
@ -200,7 +230,7 @@ impl<'a, R: Read> Read for Input<'a, R> {
}
}
impl<'a, R: Read> Input<'a, R> {
impl<'a> Input<'a> {
/// Fills a given buffer.
/// Reads in increments of 'self.ibs'.
/// The start of each ibs-sized read follows the previous one.
@ -266,20 +296,6 @@ impl<'a, R: Read> Input<'a, R> {
records_truncated: 0,
})
}
/// Skips amount_to_read bytes from the Input by copying into a sink
fn read_skip(&mut self, amount_to_read: u64) -> std::io::Result<()> {
let copy_result = io::copy(&mut self.src.by_ref().take(amount_to_read), &mut io::sink());
if let Ok(n) = copy_result {
if n != amount_to_read {
io::Result::Err(io::Error::new(io::ErrorKind::UnexpectedEof, ""))
} else {
Ok(())
}
} else {
io::Result::Err(copy_result.unwrap_err())
}
}
}
enum Density {
@ -485,7 +501,7 @@ impl<'a> Output<'a> {
///
/// If there is a problem reading from the input or writing to
/// this output.
fn dd_out<R: Read>(mut self, mut i: Input<R>) -> std::io::Result<()> {
fn dd_out(mut self, mut i: Input) -> std::io::Result<()> {
// The read and write statistics.
//
// These objects are counters, initialized to zero. After each
@ -645,12 +661,13 @@ fn make_linux_oflags(oflags: &OFlags) -> Option<libc::c_int> {
}
}
/// Read helper performs read operations common to all dd reads, and dispatches the buffer to relevant helper functions as dictated by the operations requested by the user.
fn read_helper<R: Read>(
i: &mut Input<R>,
buf: &mut Vec<u8>,
bsize: usize,
) -> std::io::Result<ReadStat> {
/// Read from an input (that is, a source of bytes) into the given buffer.
///
/// This function also performs any conversions as specified by
/// `conv=swab` or `conv=block` command-line arguments. This function
/// mutates the `buf` argument in-place. The returned [`ReadStat`]
/// indicates how many blocks were read.
fn read_helper(i: &mut Input, buf: &mut Vec<u8>, bsize: usize) -> std::io::Result<ReadStat> {
// Local Helper Fns -------------------------------------------------
fn perform_swab(buf: &mut [u8]) {
for base in (1..buf.len()).step_by(2) {
@ -794,17 +811,17 @@ pub fn uumain(args: impl uucore::Args) -> UResult<()> {
match (&settings.infile, &settings.outfile) {
(Some(infile), Some(outfile)) => {
let i = Input::<File>::new(Path::new(&infile), &settings)?;
let i = Input::new_file(Path::new(&infile), &settings)?;
let o = Output::new_file(Path::new(&outfile), &settings)?;
o.dd_out(i).map_err_context(|| "IO error".to_string())
}
(None, Some(outfile)) => {
let i = Input::<io::Stdin>::new(&settings)?;
let i = Input::new_stdin(&settings)?;
let o = Output::new_file(Path::new(&outfile), &settings)?;
o.dd_out(i).map_err_context(|| "IO error".to_string())
}
(Some(infile), None) => {
let i = Input::<File>::new(Path::new(&infile), &settings)?;
let i = Input::new_file(Path::new(&infile), &settings)?;
if is_stdout_redirected_to_seekable_file() {
let filename = stdout_canonicalized();
let o = Output::new_file(Path::new(&filename), &settings)?;
@ -815,7 +832,7 @@ pub fn uumain(args: impl uucore::Args) -> UResult<()> {
}
}
(None, None) => {
let i = Input::<io::Stdin>::new(&settings)?;
let i = Input::new_stdin(&settings)?;
if is_stdout_redirected_to_seekable_file() {
let filename = stdout_canonicalized();
let o = Output::new_file(Path::new(&filename), &settings)?;