chmod, install: move mode parsing into uucore

src/uucore/Cargo.toml

@@ -17,13 +17,14 @@ fs = ["libc"]
 utf8 = []
 encoding = ["data-encoding"]
 parse_time = []
+mode = ["libc"]
 utmpx = ["time", "libc"]
 process = ["libc"]
 signals = []
 entries = ["libc"]
 wide = []
 utsname = ["libc"]
-default = ["fs", "libc", "utf8", "utsname", "encoding", "parse_time", "utmpx", "process", "entries", "signals", "wide"]
+default = ["fs", "libc", "utf8", "utsname", "encoding", "parse_time", "mode", "utmpx", "process", "entries", "signals", "wide"]
 
 [lib]
 path = "lib.rs"

src/uucore/lib.rs

@@ -17,6 +17,8 @@ pub mod utf8;
 pub mod encoding;
 #[cfg(feature = "parse_time")]
 pub mod parse_time;
+#[cfg(feature = "mode")]
+pub mod mode;
 
 #[cfg(all(unix, not(target_os = "fuchsia"), feature = "utmpx"))]
 pub mod utmpx;

src/uucore/mode.rs

@@ -0,0 +1,129 @@
+// This file is part of the uutils coreutils package.
+//
+// (c) Alex Lyon <arcterus@mail.com>
+//
+// For the full copyright and license information, please view the LICENSE
+// file that was distributed with this source code.
+//
+
+use std::error::Error;
+
+pub fn parse_numeric(fperm: u32, mut mode: &str) -> Result<u32, String> {
+    let (op, pos) = parse_op(mode, Some('='))?;
+    mode = mode[pos..].trim_left_matches('0');
+    if mode.len() > 4 {
+        Err(format!("mode is too large ({} > 7777)", mode))
+    } else {
+        match u32::from_str_radix(mode, 8) {
+            Ok(change) => {
+                Ok(match op {
+                    '+' => fperm | change,
+                    '-' => fperm & !change,
+                    '=' => change,
+                    _ => unreachable!()
+                })
+            }
+            Err(err) => Err(err.description().to_owned())
+        }
+    }
+}
+
+pub fn parse_symbolic(mut fperm: u32, mut mode: &str, considering_dir: bool) -> Result<u32, String> {
+    #[cfg(unix)]
+    use libc::umask;
+
+    #[cfg(target_os = "redox")]
+    unsafe fn umask(_mask: u32) -> u32 {
+        // XXX Redox does not currently have umask
+        0
+    }
+
+    let (mask, pos) = parse_levels(mode);
+    if pos == mode.len() {
+        return Err(format!("invalid mode ({})", mode));
+    }
+    let respect_umask = pos == 0;
+    let last_umask = unsafe {
+        umask(0)
+    };
+    mode = &mode[pos..];
+    while mode.len() > 0 {
+        let (op, pos) = parse_op(mode, None)?;
+        mode = &mode[pos..];
+        let (mut srwx, pos) = parse_change(mode, fperm, considering_dir);
+        if respect_umask {
+            srwx &= !(last_umask as u32);
+        }
+        mode = &mode[pos..];
+        match op {
+            '+' => fperm |= srwx & mask,
+            '-' => fperm &= !(srwx & mask),
+            '=' => fperm = (fperm & !mask) | (srwx & mask),
+            _ => unreachable!()
+        }
+    }
+    unsafe {
+        umask(last_umask);
+    }
+    Ok(fperm)
+}
+
+fn parse_levels(mode: &str) -> (u32, usize) {
+    let mut mask = 0;
+    let mut pos = 0;
+    for ch in mode.chars() {
+        mask |= match ch {
+            'u' => 0o7700,
+            'g' => 0o7070,
+            'o' => 0o7007,
+            'a' => 0o7777,
+            _ => break
+        };
+        pos += 1;
+    }
+    if pos == 0 {
+        mask = 0o7777;  // default to 'a'
+    }
+    (mask, pos)
+}
+
+fn parse_op(mode: &str, default: Option<char>) -> Result<(char, usize), String> {
+    match mode.chars().next() {
+        Some(ch) => match ch {
+            '+' | '-' | '=' => Ok((ch, 1)),
+            _ => match default {
+                Some(ch) => Ok((ch, 0)),
+                None => Err(format!("invalid operator (expected +, -, or =, but found {})", ch))
+            }
+        },
+        None => Err("unexpected end of mode".to_owned())
+    }
+}
+
+fn parse_change(mode: &str, fperm: u32, considering_dir: bool) -> (u32, usize) {
+    let mut srwx = fperm & 0o7000;
+    let mut pos = 0;
+    for ch in mode.chars() {
+        match ch {
+            'r' => srwx |= 0o444,
+            'w' => srwx |= 0o222,
+            'x' => srwx |= 0o111,
+            'X' => {
+                if considering_dir || (fperm & 0o0111) != 0 {
+                    srwx |= 0o111
+                }
+            }
+            's' => srwx |= 0o4000 | 0o2000,
+            't' => srwx |= 0o1000,
+            'u' => srwx = (fperm & 0o700) | ((fperm >> 3) & 0o070) | ((fperm >> 6) & 0o007),
+            'g' => srwx = ((fperm << 3) & 0o700) | (fperm & 0o070) | ((fperm >> 3) & 0o007),
+            'o' => srwx = ((fperm << 6) & 0o700) | ((fperm << 3) & 0o070) | (fperm & 0o007),
+            _ => break
+        };
+        pos += 1;
+    }
+    if pos == 0 {
+        srwx = 0;
+    }
+    (srwx, pos)
+}