lib: split out library

Not really a satisfactorily clean split as of yet but it’s a
start. Error types have been changed from anyhow to io::Error in
``lib.rs`` so as to not force an error handling crate on
downstream users.

3 files changed, 580 insertions, 533 deletions

diff --git a/Cargo.toml b/Cargo.toml
index 82eae4e..63c199b 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -19,6 +19,10 @@ path        = "src/vtcol.rs"
 test        = false
 doc         = false
 
+[lib]
+# doctests suck
+doctest     = false
+
 [dependencies]
 clap        = "2.33"
 libc        = "0.2"
diff --git a/src/lib.rs b/src/lib.rs
new file mode 100644
index 0000000..47f650d
--- /dev/null
+++ b/src/lib.rs
@@ -0,0 +1,528 @@
+use libc::ioctl;
+use std::{convert::TryFrom,
+          fmt,
+          io::{self, BufWriter, Error, Write},
+          path::{Path, PathBuf}};
+
+pub type Fd = libc::c_int;
+
+const PALETTE_SIZE: usize = 16;
+const PALETTE_BYTES: usize = PALETTE_SIZE * 3; /* 16 * sizeof(int) */
+
+/* XXX: can we get these into ``libc``? */
+pub const KDGKBTYPE: libc::c_ulong = 0x4b33; /* kd.h */
+const GIO_CMAP: libc::c_ulong = 0x00004B70; /* kd.h */
+const PIO_CMAP: libc::c_ulong = 0x00004B71; /* kd.h */
+pub const KB_101: libc::c_char = 0x0002; /* kd.h */
+
+const RAW_COLEXPR_SIZE: usize = 6; /* e. g. 0xBADF00 */
+pub type RawPalette<'a> = [&'a str; PALETTE_SIZE];
+
+#[derive(Debug)]
+pub enum Color
+{
+    Black(bool),
+    Red(bool),
+    Green(bool),
+    Yellow(bool),
+    Blue(bool),
+    Magenta(bool),
+    Cyan(bool),
+    White(bool),
+}
+
+impl TryFrom<u8> for Color
+{
+    type Error = io::Error;
+
+    fn try_from(val: u8) -> io::Result<Self>
+    {
+        match val {
+            0x00 => Ok(Color::Black(false)),
+            0x01 => Ok(Color::Red(false)),
+            0x02 => Ok(Color::Green(false)),
+            0x03 => Ok(Color::Yellow(false)),
+            0x04 => Ok(Color::Blue(false)),
+            0x05 => Ok(Color::Magenta(false)),
+            0x06 => Ok(Color::Cyan(false)),
+            0x07 => Ok(Color::White(false)),
+
+            0x08 => Ok(Color::Black(true)),
+            0x09 => Ok(Color::Red(true)),
+            0x0a => Ok(Color::Green(true)),
+            0x0b => Ok(Color::Yellow(true)),
+            0x0c => Ok(Color::Blue(true)),
+            0x0d => Ok(Color::Magenta(true)),
+            0x0e => Ok(Color::Cyan(true)),
+            0x0f => Ok(Color::White(true)),
+
+            _ =>
+                Err(io::Error::new(
+                    io::ErrorKind::Other,
+                    format!("invalid color value: {}", val),
+                )),
+        }
+    }
+} /* [impl TryFrom<u8> for Color] */
+
+impl Color
+{
+    fn format_brightness(b: bool, s: &str) -> String
+    {
+        if b {
+            "bright ".to_string() + s
+        } else {
+            s.to_string()
+        }
+    }
+} /* [impl Color] */
+
+impl fmt::Display for Color
+{
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result
+    {
+        let c = match *self {
+            Color::Black(b) => Color::format_brightness(b, "black"),
+            Color::Red(b) => Color::format_brightness(b, "red"),
+            Color::Green(b) => Color::format_brightness(b, "green"),
+            Color::Yellow(b) => Color::format_brightness(b, "yellow"),
+            Color::Blue(b) => Color::format_brightness(b, "blue"),
+            Color::Magenta(b) => Color::format_brightness(b, "magenta"),
+            Color::Cyan(b) => Color::format_brightness(b, "cyan"),
+            Color::White(b) => Color::format_brightness(b, "white"),
+        };
+
+        write!(f, "{}", c)
+    }
+} /* [impl fmt::Display for Color] */
+
+#[derive(Debug, Clone)]
+pub struct Builtin
+{
+    names:   &'static [&'static str],
+    palette: &'static RawPalette<'static>,
+}
+
+/** Vanilla Linux colors. */
+const DEFAULT_COLORS: RawPalette = [
+    "000000", "aa0000", "00aa00", "aa5500", "0000aa", "aa00aa", "00aaaa",
+    "aaaaaa", "555555", "ff5555", "55ff55", "ffff55", "5555ff", "ff55ff",
+    "55ffff", "ffffff",
+];
+
+/** The dark (default) version of the Solarized scheme. */
+const SOLARIZED_COLORS_DARK: RawPalette = [
+    "002b36", "dc322f", "859900", "b58900", "268bd2", "d33682", "2aa198",
+    "eee8d5", "002b36", "cb4b16", "586e75", "657b83", "839496", "6c71c4",
+    "93a1a1", "fdf6e3",
+];
+
+/** The light version of the Solarized theme. */
+const SOLARIZED_COLORS_LIGHT: RawPalette = [
+    "eee8d5", "dc322f", "859900", "b58900", "268bd2", "d33682", "2aa198",
+    "073642", "fdf6e3", "cb4b16", "93a1a1", "839496", "657b83", "6c71c4",
+    "586e75", "002b36",
+];
+
+/** Bright green monochrome terminal. */
+const MONOCHROME_PHOSPHOR: RawPalette = [
+    "000000", "68fc68", "68fc68", "68fc68", "68fc68", "68fc68", "68fc68",
+    "68fc68", "68fc68", "68fc68", "68fc68", "68fc68", "68fc68", "68fc68",
+    "68fc68", "68fc68",
+];
+
+const DUMMY_COLORS: RawPalette = [
+    "000000", "ffffff", "000000", "ffffff", "000000", "ffffff", "000000",
+    "ffffff", "000000", "ffffff", "000000", "ffffff", "000000", "ffffff",
+    "000000", "ffffff",
+];
+
+pub const BUILTIN_SCHEMES: &[Builtin] = &[
+    Builtin::solarized(),
+    Builtin::solarized_light(),
+    Builtin::default(),
+    Builtin::phosphor(),
+];
+
+impl Builtin
+{
+    pub fn name(&self) -> &'static str { self.names.iter().next().unwrap() }
+
+    pub fn palette(&self) -> &RawPalette { self.palette }
+
+    const fn solarized() -> Self
+    {
+        Self {
+            names:   &["solarized", "solarized_dark", "sd"],
+            palette: &SOLARIZED_COLORS_DARK,
+        }
+    }
+
+    const fn solarized_light() -> Self
+    {
+        Self {
+            names:   &["solarized_light", "sl"],
+            palette: &SOLARIZED_COLORS_LIGHT,
+        }
+    }
+
+    const fn default() -> Self
+    {
+        Self {
+            names:   &["default", "normal", "linux"],
+            palette: &DEFAULT_COLORS,
+        }
+    }
+
+    const fn phosphor() -> Self
+    {
+        Self { names: &["phosphor", "matrix"], palette: &MONOCHROME_PHOSPHOR }
+    }
+}
+
+impl TryFrom<&str> for Builtin
+{
+    type Error = io::Error;
+
+    fn try_from(name: &str) -> Result<Self, Self::Error>
+    {
+        for b in BUILTIN_SCHEMES {
+            if b.names.contains(&name) {
+                return Ok(b.clone());
+            }
+        }
+
+        Err(io::Error::new(
+            io::ErrorKind::Other,
+            format!("no such builtin scheme: {}", name),
+        ))
+    }
+}
+
+impl<'a> fmt::Display for Builtin
+{
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result
+    {
+        write!(f, "{}", self.name())
+    }
+}
+
+#[derive(Debug)]
+pub enum Scheme
+{
+    /** One of the predefined schemes. */
+    Builtin(Builtin),
+    /** Custom ``Palette``. */
+    Palette(Palette),
+    /** Load from file. */
+    Custom(Option<PathBuf>),
+}
+
+impl<'a> fmt::Display for Scheme
+{
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result
+    {
+        match self {
+            Self::Builtin(b) => write!(f, "{}", b),
+            Self::Custom(None) => write!(f, "<read stdin>"),
+            Self::Custom(Some(fname)) => write!(f, "{}", fname.display()),
+            Self::Palette(pal) => write!(f, "palette: {}", pal),
+        }
+    }
+} /* [impl fmt::String for Scheme] */
+
+impl Scheme
+{
+    pub fn from_stdin() -> Self { Self::Custom(None) }
+
+    pub fn from_path<P: AsRef<Path>>(path: P) -> Self
+    {
+        Self::Custom(Some(path.as_ref().into()))
+    }
+} /* [impl Scheme] */
+
+/** Try to select one of the predefined schemes; if that fails,
+interpret the argument as a path. */
+impl From<&str> for Scheme
+{
+    fn from(name: &str) -> Scheme
+    {
+        Builtin::try_from(name)
+            .map(Self::Builtin)
+            .unwrap_or_else(|_| Self::from_path(name))
+    }
+}
+
+/** Try to match the palette against one of the predefined schemes. */
+impl From<Palette> for Scheme
+{
+    fn from(pal: Palette) -> Scheme
+    {
+        if pal == Palette::from(&DEFAULT_COLORS) {
+            return Self::Builtin(Builtin::default());
+        }
+        if pal == Palette::from(&SOLARIZED_COLORS_DARK) {
+            return Self::Builtin(Builtin::solarized());
+        }
+        if pal == Palette::from(&SOLARIZED_COLORS_LIGHT) {
+            return Self::Builtin(Builtin::solarized_light());
+        }
+        if pal == Palette::from(&MONOCHROME_PHOSPHOR) {
+            return Self::Builtin(Builtin::phosphor());
+        }
+
+        Self::Palette(pal)
+    }
+}
+
+fn nibble_of_char(chr: u8) -> u8
+{
+    match chr {
+        b'0'..=b'9' => chr - b'0',
+        b'a'..=b'f' => chr - b'a' + 10,
+        b'A'..=b'F' => chr - b'A' + 10,
+        _ => 0,
+    }
+}
+
+macro_rules! byte_of_hex {
+    ($ar:ident, $off:expr) => {
+        (nibble_of_char($ar[$off])) << 4 | nibble_of_char($ar[$off + 1]) as u8
+    };
+}
+
+fn rgb_of_hex_triplet(def: &str) -> (u8, u8, u8)
+{
+    let bytes = def.as_bytes();
+    let r: u8 = byte_of_hex!(bytes, 0);
+    let g: u8 = byte_of_hex!(bytes, 2);
+    let b: u8 = byte_of_hex!(bytes, 4);
+    (r, g, b)
+}
+
+#[derive(Eq, PartialEq, Clone)]
+pub struct Palette([u8; PALETTE_BYTES]);
+
+impl Palette
+{
+    /** Construct an all-zero ``Palette``. */
+    pub fn new() -> Self { Self([0u8; PALETTE_BYTES]) }
+
+    pub fn dummy() -> Self { Self::from(&DUMMY_COLORS) }
+
+    pub fn from_buffered_reader(reader: &mut dyn std::io::BufRead) -> Self
+    {
+        let mut pal_idx: usize = 0;
+        let mut pal: [u8; PALETTE_BYTES] = [0; PALETTE_BYTES];
+        let mut line: String = String::new();
+
+        while reader.read_line(&mut line).is_ok() {
+            let len = line.len();
+            if len == 0 {
+                break;
+            } else if len >= 8 {
+                if let Some(off) = line.find('#') {
+                    if off != 0 {
+                        /* Palette index specified, number prepended */
+                        let parse_res: Result<usize, _> =
+                            std::str::FromStr::from_str(&line[0..off]);
+                        if let Ok(new_idx) = parse_res {
+                            if new_idx < PALETTE_SIZE {
+                                pal_idx = new_idx * 3;
+                            }
+                        }
+                    }
+                    let off = off + 1;
+                    if off > len - 6 {
+                        /* no room left for color definition after '#' char */
+                        panic!("invalid color definition: {}", line);
+                    }
+                    let col = &line[off..(off + RAW_COLEXPR_SIZE)];
+
+                    let (r, g, b) = rgb_of_hex_triplet(col);
+                    pal[pal_idx] = r;
+                    pal[pal_idx + 1] = g;
+                    pal[pal_idx + 2] = b;
+                    pal_idx = (pal_idx + 3) % PALETTE_BYTES;
+                }
+            }
+            line.truncate(0);
+        }
+
+        Self(pal)
+    }
+
+    #[allow(rustdoc::invalid_rust_codeblocks)]
+    /** Print palette in a text format that can be re-read back in.
+    Basically we print one hex rgb code per line prefixed with color
+    indices and the canonical names on the right:
+
+        00  #002B36  black
+        01  #DC322F  red
+        02  #859900  green
+        03  #B58900  yellow
+        04  #268BD2  blue
+        …
+    */
+    pub fn dump(&self, out: &mut BufWriter<io::Stdout>) -> io::Result<()>
+    {
+        let mut buf: [u8; 3] = [0u8, 0u8, 0u8];
+        for (i, col) in self.0.iter().enumerate() {
+            let idx: usize = i % 3;
+            buf[idx] = *col;
+            if idx == 2 {
+                let col = Color::try_from((i / 3) as u8)?;
+                out.write_all(
+                    format!(
+                        "{:02}  #{:02.X}{:02.X}{:02.X}  {}\n",
+                        i / 3,
+                        buf[0],
+                        buf[1],
+                        buf[2],
+                        col,
+                    )
+                    .as_bytes(),
+                )?;
+            }
+        }
+
+        Ok(())
+    }
+
+    pub fn from_file(fname: &Path) -> Self
+    {
+        /* Check if file exists
+         */
+        let file = match std::fs::File::open(&fname) {
+            Err(e) => {
+                panic!("failed to open {} as file ({})", fname.display(), e)
+            },
+            Ok(f) => f,
+        };
+        let mut reader = std::io::BufReader::new(file);
+
+        /* Parse scheme file
+         */
+        Self::from_buffered_reader(&mut reader)
+    }
+
+    /* [Palette::from_file] */
+
+    pub fn from_stdin() -> Self
+    {
+        let mut reader = std::io::BufReader::new(std::io::stdin());
+
+        /* Parse scheme file
+         */
+        Self::from_buffered_reader(&mut reader)
+    } /* [Palette::from_stdin] */
+} /* [impl Palette] */
+
+impl fmt::Display for Palette
+{
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result
+    {
+        let mut i = 0;
+        while i < PALETTE_BYTES {
+            let _ = write!(f, "{}", if i == 0 { "(" } else { "\n " });
+            let r = self.0[i];
+            let g = self.0[i + 1];
+            let b = self.0[i + 2];
+            let _ = write!(
+                f,
+                "((r 0x{:02.X}) (g 0x{:02.X}) (b 0x{:02.x}))",
+                r, g, b
+            );
+            i += 3;
+        }
+        writeln!(f, ")")
+    }
+} /* [impl fmt::Display for Palette] */
+
+impl fmt::Debug for Palette
+{
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result
+    {
+        let mut i: u8 = 0_u8;
+        while (i as usize) < PALETTE_BYTES {
+            let r = self.0[i as usize];
+            let g = self.0[i as usize + 1];
+            let b = self.0[i as usize + 2];
+            let col = Color::try_from((i / 3) as u8)
+                .map(|c| format!("{}", c))
+                .unwrap_or_else(|_| "??".into());
+            let _ = writeln!(f, "{} => 0x{:02.X}{:02.X}{:02.X}", col, r, g, b);
+            i += 3_u8;
+        }
+        std::result::Result::Ok(())
+    }
+} /* [impl fmt::Debug for Palette] */
+
+/** Obtain a ``Palette`` from a ``Scheme``. */
+impl From<&Scheme> for Palette
+{
+    fn from(scm: &Scheme) -> Self
+    {
+        match scm {
+            Scheme::Builtin(Builtin { palette, .. }) => Self::from(*palette),
+            Scheme::Custom(None) => Self::from_stdin(),
+            Scheme::Custom(Some(ref fname)) => Self::from_file(fname),
+            Scheme::Palette(pal) => pal.clone(),
+        }
+    }
+}
+
+/** Obtain a ``Palette`` from a ``RawPalette``. */
+impl From<&RawPalette<'_>> for Palette
+{
+    fn from(colors: &RawPalette<'_>) -> Self
+    {
+        let mut idx: usize = 0;
+        let mut pal: [u8; PALETTE_BYTES] = [0; PALETTE_BYTES];
+
+        for def in colors.iter() {
+            let (r, g, b) = rgb_of_hex_triplet(*def);
+            pal[idx] = r;
+            pal[idx + 1] = g;
+            pal[idx + 2] = b;
+            //println!(">> {} -> {:X} {:X} {:X}", def, r, g, b);
+            idx += 3;
+        }
+
+        Self(pal)
+    }
+}
+
+pub fn ioctl_pio_cmap(fd: Fd, pal: &Palette) -> io::Result<()>
+{
+    if unsafe {
+        ioctl(
+            fd,
+            PIO_CMAP,
+            std::mem::transmute::<&Palette, *const libc::c_void>(&pal),
+        )
+    } < 0
+    {
+        Err(Error::last_os_error())
+    } else {
+        Ok(())
+    }
+}
+
+pub fn ioctl_gio_cmap(fd: Fd) -> io::Result<Palette>
+{
+    let mut pal = Palette::new();
+
+    if unsafe {
+        ioctl(
+            fd,
+            GIO_CMAP,
+            std::mem::transmute::<&mut Palette, *mut libc::c_void>(&mut pal),
+        )
+    } < 0
+    {
+        Err(Error::last_os_error())
+    } else {
+        Ok(pal)
+    }
+}
diff --git a/src/vtcol.rs b/src/vtcol.rs
index 5d073e7..707f96d 100644
--- a/src/vtcol.rs
+++ b/src/vtcol.rs
@@ -1,13 +1,11 @@
-#![allow(rustdoc::invalid_rust_codeblocks)]
+pub mod lib;
+
+use vtcol::{Palette, Scheme};
+
 use anyhow::{anyhow, Result};
-use std::{convert::TryFrom,
-          fmt,
-          io::{self, BufWriter, Error, Write},
-          path::{Path, PathBuf},
+use std::{io::{self, BufWriter, Error},
           sync::atomic::{AtomicBool, Ordering}};
 
-type Fd = libc::c_int;
-
 static VERBOSITY: AtomicBool = AtomicBool::new(false);
 
 macro_rules! vrb {
@@ -16,234 +14,6 @@ macro_rules! vrb {
     )}
 }
 
-const PALETTE_SIZE: usize = 16;
-const PALETTE_BYTES: usize = PALETTE_SIZE * 3; /* 16 * sizeof(int) */
-
-const RAW_COLEXPR_SIZE: usize = 6; /* e. g. 0xBADF00 */
-
-type RawPalette<'a> = [&'a str; PALETTE_SIZE];
-
-/* XXX: can we get these into ``libc``? */
-const KDGKBTYPE: libc::c_int = 0x4b33; /* kd.h */
-const GIO_CMAP: libc::c_int = 0x00004B70; /* kd.h */
-const PIO_CMAP: libc::c_int = 0x00004B71; /* kd.h */
-const KB_101: libc::c_char = 0x0002; /* kd.h */
-const O_NOCTTY: libc::c_int = 0o0400; /* fcntl.h */
-
-#[derive(Debug)]
-enum Color
-{
-    Black(bool),
-    Red(bool),
-    Green(bool),
-    Yellow(bool),
-    Blue(bool),
-    Magenta(bool),
-    Cyan(bool),
-    White(bool),
-}
-
-impl TryFrom<u8> for Color
-{
-    type Error = anyhow::Error;
-
-    fn try_from(val: u8) -> Result<Self, Self::Error>
-    {
-        match val {
-            0x00 => Ok(Color::Black(false)),
-            0x01 => Ok(Color::Red(false)),
-            0x02 => Ok(Color::Green(false)),
-            0x03 => Ok(Color::Yellow(false)),
-            0x04 => Ok(Color::Blue(false)),
-            0x05 => Ok(Color::Magenta(false)),
-            0x06 => Ok(Color::Cyan(false)),
-            0x07 => Ok(Color::White(false)),
-
-            0x08 => Ok(Color::Black(true)),
-            0x09 => Ok(Color::Red(true)),
-            0x0a => Ok(Color::Green(true)),
-            0x0b => Ok(Color::Yellow(true)),
-            0x0c => Ok(Color::Blue(true)),
-            0x0d => Ok(Color::Magenta(true)),
-            0x0e => Ok(Color::Cyan(true)),
-            0x0f => Ok(Color::White(true)),
-
-            _ => Err(anyhow!("invalid color value: {}", val)),
-        }
-    }
-} /* [impl TryFrom<u8> for Color] */
-
-impl Color
-{
-    fn format_brightness(b: bool, s: &str) -> String
-    {
-        if b {
-            "bright ".to_string() + s
-        } else {
-            s.to_string()
-        }
-    }
-} /* [impl Color] */
-
-impl fmt::Display for Color
-{
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result
-    {
-        let c = match *self {
-            Color::Black(b) => Color::format_brightness(b, "black"),
-            Color::Red(b) => Color::format_brightness(b, "red"),
-            Color::Green(b) => Color::format_brightness(b, "green"),
-            Color::Yellow(b) => Color::format_brightness(b, "yellow"),
-            Color::Blue(b) => Color::format_brightness(b, "blue"),
-            Color::Magenta(b) => Color::format_brightness(b, "magenta"),
-            Color::Cyan(b) => Color::format_brightness(b, "cyan"),
-            Color::White(b) => Color::format_brightness(b, "white"),
-        };
-
-        write!(f, "{}", c)
-    }
-} /* [impl fmt::Display for Color] */
-
-#[derive(Debug, Clone)]
-struct Builtin
-{
-    names:   &'static [&'static str],
-    palette: &'static RawPalette<'static>,
-}
-
-const BUILTIN_SCHEMES: &[Builtin] = &[
-    Builtin::solarized(),
-    Builtin::solarized_light(),
-    Builtin::default(),
-    Builtin::phosphor(),
-];
-
-impl Builtin
-{
-    fn name(&self) -> &'static str { self.names.iter().next().unwrap() }
-
-    const fn solarized() -> Self
-    {
-        Self {
-            names:   &["solarized", "solarized_dark", "sd"],
-            palette: &SOLARIZED_COLORS_DARK,
-        }
-    }
-
-    const fn solarized_light() -> Self
-    {
-        Self {
-            names:   &["solarized_light", "sl"],
-            palette: &SOLARIZED_COLORS_LIGHT,
-        }
-    }
-
-    const fn default() -> Self
-    {
-        Self {
-            names:   &["default", "normal", "linux"],
-            palette: &DEFAULT_COLORS,
-        }
-    }
-
-    const fn phosphor() -> Self
-    {
-        Self { names: &["phosphor", "matrix"], palette: &MONOCHROME_PHOSPHOR }
-    }
-}
-
-impl TryFrom<&str> for Builtin
-{
-    type Error = anyhow::Error;
-
-    fn try_from(name: &str) -> Result<Self, Self::Error>
-    {
-        for b in BUILTIN_SCHEMES {
-            if b.names.contains(&name) {
-                return Ok(b.clone());
-            }
-        }
-
-        Err(anyhow!("no such builtin: {}", name))
-    }
-}
-
-impl<'a> fmt::Display for Builtin
-{
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result
-    {
-        write!(f, "{}", self.name())
-    }
-}
-
-#[derive(Debug)]
-enum Scheme
-{
-    /** One of the predefined schemes. */
-    Builtin(Builtin),
-    /** Custom ``Palette``. */
-    Palette(Palette),
-    /** Load from file. */
-    Custom(Option<PathBuf>),
-}
-
-impl<'a> fmt::Display for Scheme
-{
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result
-    {
-        match self {
-            Self::Builtin(b) => write!(f, "{}", b),
-            Self::Custom(None) => write!(f, "<read stdin>"),
-            Self::Custom(Some(fname)) => write!(f, "{}", fname.display()),
-            Self::Palette(pal) => write!(f, "palette: {}", pal),
-        }
-    }
-} /* [impl fmt::String for Scheme] */
-
-impl Scheme
-{
-    fn from_stdin() -> Self { Self::Custom(None) }
-
-    fn from_path<P: AsRef<Path>>(path: P) -> Self
-    {
-        Self::Custom(Some(path.as_ref().into()))
-    }
-} /* [impl Scheme] */
-
-/** Try to select one of the predefined schemes; if that fails,
-interpret the argument as a path. */
-impl From<&str> for Scheme
-{
-    fn from(name: &str) -> Scheme
-    {
-        Builtin::try_from(name)
-            .map(Self::Builtin)
-            .unwrap_or_else(|_| Self::from_path(name))
-    }
-}
-
-/** Try to match the palette against one of the predefined schemes. */
-impl From<Palette> for Scheme
-{
-    fn from(pal: Palette) -> Scheme
-    {
-        if pal == Palette::from(&DEFAULT_COLORS) {
-            return Self::Builtin(Builtin::default());
-        }
-        if pal == Palette::from(&SOLARIZED_COLORS_DARK) {
-            return Self::Builtin(Builtin::solarized());
-        }
-        if pal == Palette::from(&SOLARIZED_COLORS_LIGHT) {
-            return Self::Builtin(Builtin::solarized_light());
-        }
-        if pal == Palette::from(&MONOCHROME_PHOSPHOR) {
-            return Self::Builtin(Builtin::phosphor());
-        }
-
-        Self::Palette(pal)
-    }
-}
-
 /* struct Job -- Runtime parameters.
  */
 #[derive(Debug)]
@@ -346,14 +116,14 @@ impl<'a> Job
             ("list", _) => Ok(Self::List),
             ("set", Some(subm)) => {
                 let scheme = match subm.value_of("scheme") {
-                    Some("-") => Scheme::from_stdin(),
+                    Some("-") => Self::read_scheme_from_stdin(),
                     Some(name) => {
                         vrb!("pick predefined scheme [{}]", name);
                         Scheme::from(name)
                     },
                     None =>
                         match subm.value_of("file") {
-                            None | Some("-") => Scheme::from_stdin(),
+                            None | Some("-") => Self::read_scheme_from_stdin(),
                             Some(fname) => {
                                 vrb!(
                                     "read custom scheme from file [{}]",
@@ -389,24 +159,48 @@ impl<'a> Job
 
     fn list_schemes()
     {
-        println!("{} color schemes available:", BUILTIN_SCHEMES.len());
-        for s in BUILTIN_SCHEMES {
+        println!("{} color schemes available:", vtcol::BUILTIN_SCHEMES.len());
+        for s in vtcol::BUILTIN_SCHEMES {
             println!("      * {}", s.name());
         }
     }
 
+    fn read_scheme_from_stdin() -> Scheme
+    {
+        vrb!("Go ahead, type your color scheme …");
+        vrb!("vtcol>");
+        Scheme::from_stdin()
+    }
+
     fn dump(scm: Scheme) -> Result<()>
     {
         vrb!("Dumping color scheme {}", scm);
         let mut out = BufWriter::new(io::stdout());
 
         match scm {
-            Scheme::Builtin(Builtin { palette, .. }) =>
-                Palette::from(palette).dump(&mut out),
-            Scheme::Custom(None) => Palette::from_stdin().dump(&mut out),
+            Scheme::Builtin(bltn) =>
+                Palette::from(bltn.palette()).dump(&mut out).map_err(|e| {
+                    anyhow!(
+                        "error loading builtin scheme {}: {}",
+                        bltn.name(),
+                        e
+                    )
+                }),
+            Scheme::Custom(None) =>
+                Palette::from_stdin().dump(&mut out).map_err(|e| {
+                    anyhow!("error loading palette from stdin: {}", e)
+                }),
             Scheme::Custom(Some(fname)) =>
-                Palette::from_file(&fname).dump(&mut out),
-            Scheme::Palette(pal) => pal.dump(&mut out),
+                Palette::from_file(&fname).dump(&mut out).map_err(|e| {
+                    anyhow!(
+                        "error loading palette from file [{}]: {}",
+                        fname.display(),
+                        e
+                    )
+                }),
+            Scheme::Palette(pal) =>
+                pal.dump(&mut out)
+                    .map_err(|e| anyhow!("error dumping palette: {}", e)),
         }
     }
 
@@ -431,7 +225,7 @@ impl<'a> Job
         let fd = get_console_fd()?;
         vrb!("console fd: {}", fd);
 
-        ioctl_pio_cmap(fd, &pal)?;
+        vtcol::ioctl_pio_cmap(fd, &pal)?;
 
         clear_term(fd)?;
         vrb!("successfully enabled scheme {:?}", scheme);
@@ -444,7 +238,7 @@ impl<'a> Job
         let fd = get_console_fd()?;
         vrb!("console fd: {}", fd);
 
-        let pal = ioctl_gio_cmap(fd)?;
+        let pal = vtcol::ioctl_gio_cmap(fd)?;
         let scm = Scheme::from(pal);
 
         vrb!("active scheme:");
@@ -461,7 +255,7 @@ impl<'a> Job
         let fd = get_console_fd()?;
         vrb!("console fd: {}", fd);
 
-        let pal = ioctl_gio_cmap(fd)?;
+        let pal = vtcol::ioctl_gio_cmap(fd)?;
 
         if pal == Palette::from(&one) {
             Self::set_scheme(two)
@@ -493,263 +287,10 @@ const CONSOLE_PATHS: [&str; 6] = [
     "/dev/console",
 ];
 
-/** Vanilla Linux colors. */
-const DEFAULT_COLORS: RawPalette = [
-    "000000", "aa0000", "00aa00", "aa5500", "0000aa", "aa00aa", "00aaaa",
-    "aaaaaa", "555555", "ff5555", "55ff55", "ffff55", "5555ff", "ff55ff",
-    "55ffff", "ffffff",
-];
-
-/** The dark (default) version of the Solarized scheme. */
-const SOLARIZED_COLORS_DARK: RawPalette = [
-    "002b36", "dc322f", "859900", "b58900", "268bd2", "d33682", "2aa198",
-    "eee8d5", "002b36", "cb4b16", "586e75", "657b83", "839496", "6c71c4",
-    "93a1a1", "fdf6e3",
-];
-
-/** The light version of the Solarized theme. */
-const SOLARIZED_COLORS_LIGHT: RawPalette = [
-    "eee8d5", "dc322f", "859900", "b58900", "268bd2", "d33682", "2aa198",
-    "073642", "fdf6e3", "cb4b16", "93a1a1", "839496", "657b83", "6c71c4",
-    "586e75", "002b36",
-];
-
-/** Bright green monochrome terminal. */
-const MONOCHROME_PHOSPHOR: RawPalette = [
-    "000000", "68fc68", "68fc68", "68fc68", "68fc68", "68fc68", "68fc68",
-    "68fc68", "68fc68", "68fc68", "68fc68", "68fc68", "68fc68", "68fc68",
-    "68fc68", "68fc68",
-];
-
-const DUMMY_COLORS: RawPalette = [
-    "000000", "ffffff", "000000", "ffffff", "000000", "ffffff", "000000",
-    "ffffff", "000000", "ffffff", "000000", "ffffff", "000000", "ffffff",
-    "000000", "ffffff",
-];
-
-fn nibble_of_char(chr: u8) -> u8
-{
-    match chr {
-        b'0'..=b'9' => chr - b'0',
-        b'a'..=b'f' => chr - b'a' + 10,
-        b'A'..=b'F' => chr - b'A' + 10,
-        _ => 0,
-    }
-}
-
-macro_rules! byte_of_hex {
-    ($ar:ident, $off:expr) => {
-        (nibble_of_char($ar[$off])) << 4 | nibble_of_char($ar[$off + 1]) as u8
-    };
-}
-
-fn rgb_of_hex_triplet(def: &str) -> (u8, u8, u8)
-{
-    let bytes = def.as_bytes();
-    let r: u8 = byte_of_hex!(bytes, 0);
-    let g: u8 = byte_of_hex!(bytes, 2);
-    let b: u8 = byte_of_hex!(bytes, 4);
-    (r, g, b)
-}
-
-#[derive(Eq, PartialEq, Clone)]
-pub struct Palette([u8; PALETTE_BYTES]);
-
-impl Palette
-{
-    /** Construct an all-zero ``Palette``. */
-    pub fn new() -> Self { Self([0u8; PALETTE_BYTES]) }
-
-    pub fn dummy() -> Self { Self::from(&DUMMY_COLORS) }
-
-    pub fn from_buffered_reader(reader: &mut dyn std::io::BufRead) -> Self
-    {
-        let mut pal_idx: usize = 0;
-        let mut pal: [u8; PALETTE_BYTES] = [0; PALETTE_BYTES];
-        let mut line: String = String::new();
-
-        while reader.read_line(&mut line).is_ok() {
-            let len = line.len();
-            if len == 0 {
-                break;
-            } else if len >= 8 {
-                if let Some(off) = line.find('#') {
-                    if off != 0 {
-                        /* Palette index specified, number prepended */
-                        let parse_res: Result<usize, _> =
-                            std::str::FromStr::from_str(&line[0..off]);
-                        if let Ok(new_idx) = parse_res {
-                            if new_idx < PALETTE_SIZE {
-                                pal_idx = new_idx * 3;
-                            }
-                        }
-                    }
-                    let off = off + 1;
-                    if off > len - 6 {
-                        /* no room left for color definition after '#' char */
-                        panic!("invalid color definition: {}", line);
-                    }
-                    let col = &line[off..(off + RAW_COLEXPR_SIZE)];
-
-                    let (r, g, b) = rgb_of_hex_triplet(col);
-                    pal[pal_idx] = r;
-                    pal[pal_idx + 1] = g;
-                    pal[pal_idx + 2] = b;
-                    pal_idx = (pal_idx + 3) % PALETTE_BYTES;
-                }
-            }
-            line.truncate(0);
-        }
-
-        Self(pal)
-    }
-
-    /** Print palette in a text format that can be re-read back in.
-    Basically we print one hex rgb code per line prefixed with color
-    indices and the canonical names on the right:
-
-        00  #002B36  black
-        01  #DC322F  red
-        02  #859900  green
-        03  #B58900  yellow
-        04  #268BD2  blue
-        …
-    */
-    fn dump(&self, out: &mut BufWriter<io::Stdout>) -> Result<()>
-    {
-        let mut buf: [u8; 3] = [0u8, 0u8, 0u8];
-        for (i, col) in self.0.iter().enumerate() {
-            let idx: usize = i % 3;
-            buf[idx] = *col;
-            if idx == 2 {
-                let col = Color::try_from((i / 3) as u8)?;
-                out.write_all(
-                    format!(
-                        "{:02}  #{:02.X}{:02.X}{:02.X}  {}\n",
-                        i / 3,
-                        buf[0],
-                        buf[1],
-                        buf[2],
-                        col,
-                    )
-                    .as_bytes(),
-                )?;
-            }
-        }
-
-        Ok(())
-    }
-
-    pub fn from_file(fname: &Path) -> Self
-    {
-        /* Check if file exists
-         */
-        let file = match std::fs::File::open(&fname) {
-            Err(e) => {
-                panic!("failed to open {} as file ({})", fname.display(), e)
-            },
-            Ok(f) => f,
-        };
-        let mut reader = std::io::BufReader::new(file);
-
-        /* Parse scheme file
-         */
-        Self::from_buffered_reader(&mut reader)
-    }
-
-    /* [Palette::from_file] */
-
-    pub fn from_stdin() -> Self
-    {
-        vrb!("Go ahead, type your color scheme …");
-        vrb!("vtcol>");
-        let mut reader = std::io::BufReader::new(std::io::stdin());
-
-        /* Parse scheme file
-         */
-        Self::from_buffered_reader(&mut reader)
-    } /* [Palette::from_stdin] */
-} /* [impl Palette] */
-
-impl fmt::Display for Palette
-{
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result
-    {
-        let mut i = 0;
-        while i < PALETTE_BYTES {
-            let _ = write!(f, "{}", if i == 0 { "(" } else { "\n " });
-            let r = self.0[i];
-            let g = self.0[i + 1];
-            let b = self.0[i + 2];
-            let _ = write!(
-                f,
-                "((r 0x{:02.X}) (g 0x{:02.X}) (b 0x{:02.x}))",
-                r, g, b
-            );
-            i += 3;
-        }
-        writeln!(f, ")")
-    }
-} /* [impl fmt::Display for Palette] */
-
-impl fmt::Debug for Palette
-{
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result
-    {
-        let mut i: u8 = 0_u8;
-        while (i as usize) < PALETTE_BYTES {
-            let r = self.0[i as usize];
-            let g = self.0[i as usize + 1];
-            let b = self.0[i as usize + 2];
-            let col = Color::try_from((i / 3) as u8)
-                .map(|c| format!("{}", c))
-                .unwrap_or_else(|_| "??".into());
-            let _ = writeln!(f, "{} => 0x{:02.X}{:02.X}{:02.X}", col, r, g, b);
-            i += 3_u8;
-        }
-        std::result::Result::Ok(())
-    }
-} /* [impl fmt::Debug for Palette] */
-
-/** Obtain a ``Palette`` from a ``Scheme``. */
-impl From<&Scheme> for Palette
-{
-    fn from(scm: &Scheme) -> Self
-    {
-        match scm {
-            Scheme::Builtin(Builtin { palette, .. }) => Self::from(*palette),
-            Scheme::Custom(None) => Self::from_stdin(),
-            Scheme::Custom(Some(ref fname)) => Self::from_file(fname),
-            Scheme::Palette(pal) => pal.clone(),
-        }
-    }
-}
-
-/** Obtain a ``Palette`` from a ``RawPalette``. */
-impl From<&RawPalette<'_>> for Palette
-{
-    fn from(colors: &RawPalette<'_>) -> Self
-    {
-        let mut idx: usize = 0;
-        let mut pal: [u8; PALETTE_BYTES] = [0; PALETTE_BYTES];
-
-        for def in colors.iter() {
-            let (r, g, b) = rgb_of_hex_triplet(*def);
-            pal[idx] = r;
-            pal[idx + 1] = g;
-            pal[idx + 2] = b;
-            //println!(">> {} -> {:X} {:X} {:X}", def, r, g, b);
-            idx += 3;
-        }
-
-        Self(pal)
-    }
-}
-
-fn fd_of_path(path: &std::path::Path) -> Option<Fd>
+fn fd_of_path(path: &std::path::Path) -> Option<vtcol::Fd>
 {
     let p = std::ffi::CString::new(path.to_str().unwrap()).unwrap();
-    match unsafe { libc::open(p.as_ptr(), libc::O_RDWR | O_NOCTTY, 0) } {
+    match unsafe { libc::open(p.as_ptr(), libc::O_RDWR | libc::O_NOCTTY, 0) } {
         -1 => None,
         fd => {
             vrb!("  *> got fd");
@@ -763,7 +304,7 @@ fn fd_of_path(path: &std::path::Path) -> Option<Fd>
             let res = unsafe {
                 ioctl(
                     fd,
-                    KDGKBTYPE as libc::c_int,
+                    vtcol::KDGKBTYPE as libc::c_int,
                     std::mem::transmute(&mut tty_type),
                 )
             };
@@ -772,7 +313,7 @@ fn fd_of_path(path: &std::path::Path) -> Option<Fd>
                 return None;
             }
 
-            if tty_type != KB_101 {
+            if tty_type != vtcol::KB_101 {
                 return None;
             }
 
@@ -781,7 +322,7 @@ fn fd_of_path(path: &std::path::Path) -> Option<Fd>
     }
 }
 
-fn get_console_fd() -> Result<Fd>
+fn get_console_fd() -> Result<vtcol::Fd>
 {
     for path in CONSOLE_PATHS.iter() {
         vrb!("trying path: {:?}", path);
@@ -794,7 +335,7 @@ fn get_console_fd() -> Result<Fd>
     Err(anyhow!("could not retrieve fd for any of the search paths"))
 }
 
-fn write_to_term(fd: Fd, buf: &str) -> Result<()>
+fn write_to_term(fd: vtcol::Fd, buf: &str) -> Result<()>
 {
     let len = buf.len() as libc::size_t;
 
@@ -812,7 +353,7 @@ fn write_to_term(fd: Fd, buf: &str) -> Result<()>
     }
 }
 
-fn clear_term(fd: Fd) -> Result<()>
+fn clear_term(fd: vtcol::Fd) -> Result<()>
 {
     let clear = "\x1b[2J";
     let cursor = "\x1b[1;1H";
@@ -822,32 +363,6 @@ fn clear_term(fd: Fd) -> Result<()>
     Ok(())
 }
 
-fn ioctl_pio_cmap(fd: Fd, pal: &Palette) -> Result<()>
-{
-    if unsafe { ioctl(fd, PIO_CMAP, std::mem::transmute(pal)) } < 0 {
-        Err(anyhow!(
-            "ioctl(PIO_CMAP) failed to insert new palette: {}",
-            Error::last_os_error()
-        ))
-    } else {
-        Ok(())
-    }
-}
-
-fn ioctl_gio_cmap(fd: Fd) -> Result<Palette>
-{
-    let mut pal = Palette::new();
-
-    if unsafe { ioctl(fd, GIO_CMAP, std::mem::transmute(&mut pal)) } < 0 {
-        Err(anyhow!(
-            "ioctl(GIO_CMAP) failed to get current palette: {}",
-            Error::last_os_error()
-        ))
-    } else {
-        Ok(pal)
-    }
-}
-
 fn main() -> Result<()>
 {
     let job = Job::from_argv()?;