pmap: use Perms struct instead of String for perms

Author: cakebaker

src/uu/pmap/src/maps_format_parser.rs

@@ -3,6 +3,7 @@
 // For the full copyright and license information, please view the LICENSE
 // file that was distributed with this source code.
 
+use std::fmt;
 use std::io::{Error, ErrorKind};
 
 // Represents a parsed single line from /proc/<PID>/maps for the default and device formats. It
@@ -11,12 +12,50 @@ use std::io::{Error, ErrorKind};
 pub struct MapLine {
     pub address: String,
     pub size_in_kb: u64,
-    pub perms: String,
+    pub perms: Perms,
     pub offset: String,
     pub device: String,
     pub mapping: String,
 }
 
+// Represents a set of permissions from the "perms" column of /proc/<PID>/maps.
+#[derive(Clone, Copy, Debug, PartialEq)]
+pub struct Perms {
+    pub readable: bool,
+    pub writable: bool,
+    pub executable: bool,
+    pub shared: bool,
+}
+
+impl From<&str> for Perms {
+    fn from(s: &str) -> Self {
+        let mut chars = s.chars();
+
+        Self {
+            readable: chars.next() == Some('r'),
+            writable: chars.next() == Some('w'),
+            executable: chars.next() == Some('x'),
+            shared: chars.next() == Some('s'),
+        }
+    }
+}
+
+// Please note: While `Perms` has four boolean fields, it's string representation has five
+// characters because pmap's default and device formats use five characters for the perms,
+// with the last character always being '-'.
+impl fmt::Display for Perms {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(
+            f,
+            "{}{}{}{}-",
+            if self.readable { 'r' } else { '-' },
+            if self.writable { 'w' } else { '-' },
+            if self.executable { 'x' } else { '-' },
+            if self.shared { 's' } else { '-' },
+        )
+    }
+}
+
 // Parses a single line from /proc/<PID>/maps. See
 // https://www.kernel.org/doc/html/latest/filesystems/proc.html for details about the expected
 // format.
@@ -33,7 +72,7 @@ pub fn parse_map_line(line: &str) -> Result<MapLine, Error> {
     let (perms, rest) = rest
         .split_once(' ')
         .ok_or_else(|| Error::from(ErrorKind::InvalidData))?;
-    let perms = parse_perms(perms);
+    let perms = Perms::from(perms);
 
     let (offset, rest) = rest
         .split_once(' ')
@@ -74,15 +113,6 @@ fn parse_address(memory_range: &str) -> Result<(String, u64), Error> {
     Ok((format!("{start:0>16}"), size_in_kb))
 }
 
-// Turns a 4-char perms string from /proc/<PID>/maps into a 5-char perms string. The first three
-// chars are left untouched.
-fn parse_perms(perms: &str) -> String {
-    let perms = perms.replace("p", "-");
-
-    // the fifth char seems to be always '-' in the original pmap
-    format!("{perms}-")
-}
-
 // Pads the device info from /proc/<PID>/maps with zeros and turns AB:CD into 0AB:000CD.
 fn parse_device(device: &str) -> Result<String, Error> {
     let (major, minor) = device
@@ -113,50 +143,57 @@ mod test {
     fn create_map_line(
         address: &str,
         size_in_kb: u64,
-        perms: &str,
+        perms: Perms,
         offset: &str,
         device: &str,
         mapping: &str,
     ) -> MapLine {
         MapLine {
             address: address.to_string(),
             size_in_kb,
-            perms: perms.to_string(),
+            perms,
             offset: offset.to_string(),
             device: device.to_string(),
             mapping: mapping.to_string(),
         }
     }
 
+    #[test]
+    fn test_perms_to_string() {
+        assert_eq!("-----", Perms::from("---p").to_string());
+        assert_eq!("---s-", Perms::from("---s").to_string());
+        assert_eq!("rwx--", Perms::from("rwxp").to_string());
+    }
+
     #[test]
     fn test_parse_map_line() {
         let data = [
             (
-                create_map_line("000062442eb9e000", 16, "r----", "0000000000000000", "008:00008", "konsole"),
+                create_map_line("000062442eb9e000", 16, Perms::from("r--p"), "0000000000000000", "008:00008", "konsole"),
                 "62442eb9e000-62442eba2000 r--p 00000000 08:08 10813151                   /usr/bin/konsole"
             ),
             (
-                create_map_line("000071af50000000", 132, "rw---", "0000000000000000", "000:00000", "  [ anon ]"),
+                create_map_line("000071af50000000", 132, Perms::from("rw-p"), "0000000000000000", "000:00000", "  [ anon ]"),
                 "71af50000000-71af50021000 rw-p 00000000 00:00 0 "
             ),
             (
-                create_map_line("00007ffc3f8df000", 132, "rw---", "0000000000000000", "000:00000", "  [ stack ]"),
+                create_map_line("00007ffc3f8df000", 132, Perms::from("rw-p"), "0000000000000000", "000:00000", "  [ stack ]"),
                 "7ffc3f8df000-7ffc3f900000 rw-p 00000000 00:00 0                          [stack]"
             ),
             (
-                create_map_line("000071af8c9e6000", 16, "rw-s-", "0000000105830000", "000:00010", "  [ anon ]"),
+                create_map_line("000071af8c9e6000", 16, Perms::from("rw-s"), "0000000105830000", "000:00010", "  [ anon ]"),
                 "71af8c9e6000-71af8c9ea000 rw-s 105830000 00:10 1075                      anon_inode:i915.gem"
             ),
             (
-                create_map_line("000071af6cf0c000", 3560, "rw-s-", "0000000000000000", "000:00001", "memfd:wayland-shm (deleted)"),
+                create_map_line("000071af6cf0c000", 3560, Perms::from("rw-s"), "0000000000000000", "000:00001", "memfd:wayland-shm (deleted)"),
                 "71af6cf0c000-71af6d286000 rw-s 00000000 00:01 256481                     /memfd:wayland-shm (deleted)"
             ),
             (
-                create_map_line("ffffffffff600000", 4, "--x--", "0000000000000000", "000:00000", "  [ anon ]"),
+                create_map_line("ffffffffff600000", 4, Perms::from("--xp"), "0000000000000000", "000:00000", "  [ anon ]"),
                 "ffffffffff600000-ffffffffff601000 --xp 00000000 00:00 0                  [vsyscall]"
             ),
             (
-                create_map_line("00005e8187da8000", 24, "r----", "0000000000000000", "008:00008", "hello   world"),
+                create_map_line("00005e8187da8000", 24, Perms::from("r--p"), "0000000000000000", "008:00008", "hello   world"),
                 "5e8187da8000-5e8187dae000 r--p 00000000 08:08 9524160                    /usr/bin/hello   world"
             ),
         ];
@@ -193,13 +230,6 @@ mod test {
         assert!(parse_address("ffffffffff600000-zfffffffff601000").is_err());
     }
 
-    #[test]
-    fn test_parse_perms() {
-        assert_eq!("-----", parse_perms("---p"));
-        assert_eq!("---s-", parse_perms("---s"));
-        assert_eq!("rwx--", parse_perms("rwxp"));
-    }
-
     #[test]
     fn test_parse_device() {
         assert_eq!("012:00034", parse_device("12:34").unwrap());