od: Accept multiple files names as input

src/od/od.rs

@@ -14,7 +14,9 @@ extern crate getopts;
 use std::fs::File;
 use std::io::Read;
 use std::mem;
-use std::path::Path;
+use std::io::BufReader;
+use std::io::Write;
+use std::io;
  
 #[derive(Debug)]
 enum Radix { Decimal, Hexadecimal, Octal, Binary }
@@ -51,30 +53,96 @@ pub fn uumain(args: Vec<String>) -> i32 {
         Err(f) => { panic!("Invalid -A/--address-radix\n{}", f) }
     };
  
-    let fname = match args.last() {
-        Some(n) => n,
-        None => { panic!("Need fname for now") ; }
+    // Gather up file names - args wich don't start with '-'
+    let fnames = args[1..]
+                     .iter()
+                     .filter(|w| !w.starts_with('-'))
+                     .map(|x| x.clone())
+                     .collect::<Vec<_>>();
+ 
+    // With no filenames, od would use stdin as input, which is currently not supported.
+    if fnames.len() == 0 {
+        panic!("Need fname for now") ;
     };
-
-    odfunc(&input_offset_base, &fname);
-
-    0
+    odfunc(&input_offset_base, fnames)
 }
 
 const LINEBYTES:usize = 16;
 const WORDBYTES:usize = 2;
  
-fn odfunc(input_offset_base: &Radix, fname: &str) {
-    let mut f = match File::open(Path::new(fname)) {
-        Ok(f) => f,
-        Err(e) => panic!("file error: {}", e)
+fn odfunc(input_offset_base: &Radix, fnames: Vec<String>) -> i32 {
+
+    let mut status = 0;
+    let mut ni = fnames.iter();
+    {
+        // Open and return the next file to process as a BufReader
+        // Returns None when no more files.
+        let mut next_file = || -> Option<BufReader<File>> {
+            // loop retries with subsequent files if err - normally 'loops' once
+            loop {
+                let fname = match ni.next() {
+                    None => return None,
+                    Some(s) => s,
+                };
+                match File::open(fname) {
+                    Ok(f) => return Some(BufReader::new(f)),
+                    Err(e) => {
+                        // If any file can't be opened,
+                        // print an error at the time that the file is needed,
+                        // then move on the the next file.
+                        // This matches the behavior of the original `od`
+                        let _ = writeln!(&mut std::io::stderr(), "od: '{}': {}", fname, e);
+                        if status == 0 {status = 1}
+                    }
+                }
+            }
+        };
+
+        let mut curr_file: BufReader<File> = match next_file() {
+            Some(f) => f, 
+            None => {
+                return 1;
+            } 
+        };
+
+        let mut exhausted = false; // There is no more input, gone to the end of the last file.
+
+        // Fill buf with bytes read from the list of files
+        // Returns Ok(<number of bytes read>) 
+        // Handles io errors itself, thus always returns OK
+        // Fills the provided buffer completely, unless it has run out of input.
+        // If any call returns short (< buf.len()), all subsequent calls will return Ok<0>
+        let mut f_read = |buf: &mut [u8]| -> io::Result<usize> {
+            if exhausted {
+                Ok(0)
+            } else {
+                let mut xfrd = 0;
+                while xfrd < buf.len() {
+                    xfrd += match curr_file.read(&mut buf[xfrd..]) {
+                        Ok(n) => n,
+                        Err(e) => panic!("file error: {}", e),
+                    };
+                    if xfrd == buf.len() {
+                        // transferred all that was asked for.
+                        break;
+                    }
+                    curr_file = match next_file() { 
+                        Some(f) => f, 
+                        None => {
+                            exhausted = true;
+                            break;
+                        } 
+                    };
+                }
+                Ok(xfrd)
+            }
         };
  
         let mut addr = 0;
         let bytes = &mut [b'\x00'; LINEBYTES];
         loop { // print each line
             print_with_radix(input_offset_base, addr); // print offset
-        match f.read(bytes) {
+            match f_read(bytes) {
                 Ok(0) => {
                     print!("\n");
                     break;
@@ -106,6 +174,8 @@ fn odfunc(input_offset_base: &Radix, fname: &str) {
                 }
             };
         };
+    };
+    status
 }
 
 fn parse_radix(radix_str: Option<String>) -> Result<Radix, &'static str> {