feature: User info in proc widget for Unix-based systems (#425)

Adds users into the process widget (for Unix-based systems).  This shows only in non-grouped modes, similar to state.  Search is also supported.

In addition, a quick fix to prevent users from being in grouped mode when they tried to enter tree mode while grouped.

13 files changed, 265 insertions, 48 deletions

diff --git a/.vscode/settings.json b/.vscode/settings.json
index a04896e8..5d567693 100644
--- a/.vscode/settings.json
+++ b/.vscode/settings.json
@@ -67,11 +67,13 @@
     "cvars",
     "czvf",
     "denylist",
+    "doctest",
     "dont",
     "eselect",
     "fedoracentos",
     "fpath",
     "fract",
+    "getpwuid",
     "gnueabihf",
     "gotop",
     "gotop's",
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 3176e72b..0cc22531 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -9,19 +9,21 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## Features
 
-- [#263](https://github.com/ClementTsang/bottom/pull/263): Adds the option for fine-grained kill signals on Unix-like systems.
+- [#263](https://github.com/ClementTsang/bottom/pull/263): Added the option for fine-grained kill signals on Unix-like systems.
 
-- [#333](https://github.com/ClementTsang/bottom/pull/333): Adds an "out of" indicator that can be enabled using `--show_table_scroll_position` (and its corresponding config option) to help keep track of scrolled position.
+- [#333](https://github.com/ClementTsang/bottom/pull/333): Added an "out of" indicator that can be enabled using `--show_table_scroll_position` (and its corresponding config option) to help keep track of scrolled position.
 
-- [#379](https://github.com/ClementTsang/bottom/pull/379): Adds `--process_command` flag and corresponding config option to default to showing a process' command.
+- [#379](https://github.com/ClementTsang/bottom/pull/379): Added `--process_command` flag and corresponding config option to default to showing a process' command.
 
-- [#381](https://github.com/ClementTsang/bottom/pull/381): Adds a filter in the config file for network interfaces.
+- [#381](https://github.com/ClementTsang/bottom/pull/381): Added a filter in the config file for network interfaces.
 
-- [#406](https://github.com/ClementTsang/bottom/pull/406): Adds the Nord colour scheme, as well as a light variant.
+- [#406](https://github.com/ClementTsang/bottom/pull/406): Added the Nord colour scheme, as well as a light variant.
 
-- [#409](https://github.com/ClementTsang/bottom/pull/409): Adds `Ctrl-w` and `Ctrl-h` shortcuts in search, to delete a word and delete a character respectively.
+- [#409](https://github.com/ClementTsang/bottom/pull/409): Added `Ctrl-w` and `Ctrl-h` shortcuts in search, to delete a word and delete a character respectively.
 
-- [#413](https://github.com/ClementTsang/bottom/pull/413): Adds mouse support for sorting process columns.
+- [#413](https://github.com/ClementTsang/bottom/pull/413): Added mouse support for sorting process columns.
+
+- [#425](https://github.com/ClementTsang/bottom/pull/425): Added user into the process widget for Unix-based systems.
 
 ## Changes
 
@@ -43,6 +45,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 - [#423](https://github.com/ClementTsang/bottom/pull/423): Fixes disk encryption causing the disk widget to fail or not properly map I/O statistics.
 
+- [#425](https://github.com/ClementTsang/bottom/pull/425): Fixed a bug allowing grouped mode in tree mode if already in grouped mode.
+
 ## [0.5.7] - 2021-01-30
 
 ## Bug Fixes
diff --git a/Cargo.toml b/Cargo.toml
index 7e944d23..b9351b53 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -17,6 +17,11 @@ name = "btm"
 path = "src/bin/main.rs"
 doc = false
 
+[lib]
+test = false
+doctest = false
+doc = false
+
 [profile.release]
 debug = 0
 lto = true
diff --git a/README.md b/README.md
index a899ef27..f0a929ff 100644
--- a/README.md
+++ b/README.md
@@ -387,6 +387,7 @@ Use `btm --help` for more information.
 | `write`, `w/s`      | `write >= 1 kb`    | Matches the write/s column in terms of bytes; supports comparison operators     |
 | `tread`, `t.read`   | `tread <= 1024 gb` | Matches he total read column in terms of bytes; supports comparison operators   |
 | `twrite`, `t.write` | `twrite > 1024 tb` | Matches the total write column in terms of bytes; supports comparison operators |
+| `user`              | `user=root`        | Matches by user; supports regex                                                 |
 | `state`             | `state=running`    | Matches by state; supports regex                                                |
 
 #### Supported comparison operators
@@ -464,7 +465,7 @@ As yet _another_ process/system visualization and management application, bottom
 
 - Display temperatures from sensors
 
-- Display information regarding processes, like CPU, memory, I/O usage, and process state
+- Display information regarding processes, like CPU, memory, I/O usage, user, and process state
 
 - Process management (well, if process killing is all you need)
 
diff --git a/src/app.rs b/src/app.rs
index 8be7394d..3c0fc9d5 100644
--- a/src/app.rs
+++ b/src/app.rs
@@ -121,6 +121,10 @@ pub struct App {
     #[builder(default = false, setter(skip))]
     pub did_config_fail_to_save: bool,
 
+    #[cfg(target_family = "unix")]
+    #[builder(default, setter(skip))]
+    pub user_table: processes::UserTable,
+
     pub cpu_state: CpuState,
     pub mem_state: MemState,
     pub net_state: NetState,
@@ -310,23 +314,35 @@ impl App {
 
                             // Forcefully switch off column if we were on it...
                             if (proc_widget_state.is_grouped
-                                && proc_widget_state.process_sorting_type
-                                    == data_harvester::processes::ProcessSorting::Pid)
+                                && (proc_widget_state.process_sorting_type
+                                    == processes::ProcessSorting::Pid
+                                    || proc_widget_state.process_sorting_type
+                                        == processes::ProcessSorting::User
+                                    || proc_widget_state.process_sorting_type
+                                        == processes::ProcessSorting::State))
                                 || (!proc_widget_state.is_grouped
                                     && proc_widget_state.process_sorting_type
-                                        == data_harvester::processes::ProcessSorting::Count)
+                                        == processes::ProcessSorting::Count)
                             {
                                 proc_widget_state.process_sorting_type =
-                                    data_harvester::processes::ProcessSorting::CpuPercent; // Go back to default, negate PID for group
+                                    processes::ProcessSorting::CpuPercent; // Go back to default, negate PID for group
                                 proc_widget_state.is_process_sort_descending = true;
                             }
 
-                            proc_widget_state
-                                .columns
-                                .column_mapping
-                                .get_mut(&processes::ProcessSorting::State)
-                                .unwrap()
-                                .enabled = !(proc_widget_state.is_grouped);
+                            proc_widget_state.columns.set_to_sorted_index_from_type(
+                                &proc_widget_state.process_sorting_type,
+                            );
+
+                            proc_widget_state.columns.try_set(
+                                &processes::ProcessSorting::State,
+                                !(proc_widget_state.is_grouped),
+                            );
+
+                            #[cfg(target_family = "unix")]
+                            proc_widget_state.columns.try_set(
+                                &processes::ProcessSorting::User,
+                                !(proc_widget_state.is_grouped),
+                            );
 
                             proc_widget_state
                                 .columns
@@ -657,6 +673,26 @@ impl App {
             proc_widget_state.is_tree_mode = !proc_widget_state.is_tree_mode;
 
             if proc_widget_state.is_tree_mode {
+                // Disable grouping if so!
+                proc_widget_state.is_grouped = false;
+
+                proc_widget_state
+                    .columns
+                    .try_enable(&processes::ProcessSorting::State);
+
+                #[cfg(target_family = "unix")]
+                proc_widget_state
+                    .columns
+                    .try_enable(&processes::ProcessSorting::User);
+
+                proc_widget_state
+                    .columns
+                    .try_disable(&processes::ProcessSorting::Count);
+
+                proc_widget_state
+                    .columns
+                    .try_enable(&processes::ProcessSorting::Pid);
+
                 // We enabled... set PID sort type to ascending.
                 proc_widget_state.process_sorting_type = processes::ProcessSorting::Pid;
                 proc_widget_state.is_process_sort_descending = false;
diff --git a/src/app/data_harvester/processes.rs b/src/app/data_harvester/processes.rs
index c9233337..56bf09d4 100644
--- a/src/app/data_harvester/processes.rs
+++ b/src/app/data_harvester/processes.rs
@@ -2,8 +2,11 @@ use crate::Pid;
 use std::path::PathBuf;
 use sysinfo::ProcessStatus;
 
+#[cfg(target_family = "unix")]
+use crate::utils::error;
+
 #[cfg(target_os = "linux")]
-use crate::utils::error::{self, BottomError};
+use crate::utils::error::BottomError;
 
 #[cfg(target_os = "linux")]
 use fnv::{FnvHashMap, FnvHashSet};
@@ -29,28 +32,29 @@ pub enum ProcessSorting {
     TotalRead,
     TotalWrite,
     State,
+    User,
     Count,
 }
 
 impl std::fmt::Display for ProcessSorting {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        use ProcessSorting::*;
         write!(
             f,
             "{}",
             match &self {
-                CpuPercent => "CPU%",
-                MemPercent => "Mem%",
-                Mem => "Mem",
-                ReadPerSecond => "R/s",
-                WritePerSecond => "W/s",
-                TotalRead => "T.Read",
-                TotalWrite => "T.Write",
-                State => "State",
-                ProcessName => "Name",
-                Command => "Command",
-                Pid => "PID",
-                Count => "Count",
+                ProcessSorting::CpuPercent => "CPU%",
+                ProcessSorting::MemPercent => "Mem%",
+                ProcessSorting::Mem => "Mem",
+                ProcessSorting::ReadPerSecond => "R/s",
+                ProcessSorting::WritePerSecond => "W/s",
+                ProcessSorting::TotalRead => "T.Read",
+                ProcessSorting::TotalWrite => "T.Write",
+                ProcessSorting::State => "State",
+                ProcessSorting::ProcessName => "Name",
+                ProcessSorting::Command => "Command",
+                ProcessSorting::Pid => "PID",
+                ProcessSorting::Count => "Count",
+                ProcessSorting::User => "User",
             }
         )
     }
@@ -81,9 +85,13 @@ pub struct ProcessHarvest {
     pub process_state_char: char,
 
     /// This is the *effective* user ID.
-    pub uid: Option<u32>,
-    // pub real_uid: Option<u32>, // TODO: Add real user ID
-    pub gid: Option<u32>,
+    #[cfg(target_family = "unix")]
+    pub uid: Option<libc::uid_t>,
+
+    // TODO: Add real user ID
+    // pub real_uid: Option<u32>,
+    #[cfg(target_family = "unix")]
+    pub gid: Option<libc::gid_t>,
 }
 
 #[derive(Debug, Default, Clone)]
@@ -114,6 +122,29 @@ impl PrevProcDetails {
     }
 }
 
+#[cfg(target_family = "unix")]
+#[derive(Debug, Default)]
+pub struct UserTable {
+    pub uid_user_mapping: std::collections::HashMap<libc::uid_t, String>,
+}
+
+#[cfg(target_family = "unix")]
+impl UserTable {
+    pub fn get_uid_to_username_mapping(&mut self, uid: libc::uid_t) -> error::Result<String> {
+        if let Some(user) = self.uid_user_mapping.get(&uid) {
+            Ok(user.clone())
+        } else {
+            let passwd = unsafe { libc::getpwuid(uid) };
+            let username = unsafe { std::ffi::CStr::from_ptr((*passwd).pw_name) }
+                .to_str()?
+                .to_string();
+            self.uid_user_mapping.insert(uid, username.clone());
+
+            Ok(username)
+        }
+    }
+}
+
 #[cfg(target_os = "linux")]
 fn cpu_usage_calculation(
     prev_idle: &mut f64, prev_non_idle: &mut f64,
@@ -591,8 +622,6 @@ pub fn get_process_data(
                 total_write_bytes: disk_usage.total_written_bytes,
                 process_state: process_val.status().to_string().to_string(),
                 process_state_char: convert_process_status_to_char(process_val.status()),
-                uid: None,
-                gid: None,
             });
         }
     }
diff --git a/src/app/query.rs b/src/app/query.rs
index 79f61e73..5a827aec 100644
--- a/src/app/query.rs
+++ b/src/app/query.rs
@@ -26,7 +26,8 @@ pub trait ProcessQuery {
     /// - PIDs: Use prefix `pid`, can use regex or match word (case is irrelevant).
     /// - CPU: Use prefix `cpu`, cannot use r/m/c (regex, match word, case).  Can compare.
     /// - MEM: Use prefix `mem`, cannot use r/m/c.  Can compare.
-    /// - STATE: Use prefix `state`, TODO when we update how state looks in 0.5 probably.
+    /// - STATE: Use prefix `state`, can use regex, match word, or case.
+    /// - USER: Use prefix `user`, can use regex, match word, or case.
     /// - Read/s: Use prefix `r`.  Can compare.
     /// - Write/s: Use prefix `w`.  Can compare.
     /// - Total read: Use prefix `read`.  Can compare.
@@ -128,8 +129,6 @@ impl ProcessQuery for ProcWidgetState {
 
         fn process_prefix(query: &mut VecDeque<String>, inside_quotation: bool) -> Result<Prefix> {
             if let Some(queue_top) = query.pop_front() {
-                // debug!("Prefix QT: {:?}", queue_top);
-
                 if inside_quotation {
                     if queue_top == "\"" {
                         // This means we hit something like "".  Return an empty prefix, and to deal with
@@ -264,11 +263,20 @@ impl ProcessQuery for ProcWidgetState {
                                     compare_prefix: None,
                                 })
                             }
-                            PrefixType::Pid | PrefixType::State => {
+                            PrefixType::Pid | PrefixType::State | PrefixType::User => {
                                 // We have to check if someone put an "="...
                                 if content == "=" {
                                     // Check next string if possible
                                     if let Some(queue_next) = query.pop_front() {
+                                        // TODO: Need to consider the following cases:
+                                        // - (test)
+                                        // - (test
+                                        // - test)
+                                        // These are split into 2 to 3 different strings due to parentheses being
+                                        // delimiters in our query system.
+                                        //
+                                        // Do we want these to be valid?  They should, as a string, right?
+
                                         return Ok(Prefix {
                                             or: None,
                                             regex_prefix: Some((
@@ -580,6 +588,7 @@ pub enum PrefixType {
     TWrite,
     Name,
     State,
+    User,
     __Nonexhaustive,
 }
 
@@ -602,6 +611,7 @@ impl std::str::FromStr for PrefixType {
             "twrite" | "t.write" => Ok(TWrite),
             "pid" => Ok(Pid),
             "state" => Ok(State),
+            "user" => Ok(User),
             _ => Ok(Name),
         }
     }
@@ -628,7 +638,7 @@ impl Prefix {
         } else if let Some((prefix_type, StringQuery::Value(regex_string))) = &mut self.regex_prefix
         {
             match prefix_type {
-                PrefixType::Pid | PrefixType::Name | PrefixType::State => {
+                PrefixType::Pid | PrefixType::Name | PrefixType::State | PrefixType::User => {
                     let escaped_regex: String;
                     let final_regex_string = &format!(
                         "{}{}{}{}",
@@ -681,6 +691,13 @@ impl Prefix {
                     }),
                     PrefixType::Pid => r.is_match(process.pid.to_string().as_str()),
                     PrefixType::State => r.is_match(process.process_state.as_str()),
+                    PrefixType::User => {
+                        if let Some(user) = &process.user {
+                            r.is_match(user.as_str())
+                        } else {
+                            false
+                        }
+                    }
                     _ => true,
                 }
             } else {
diff --git a/src/app/states.rs b/src/app/states.rs
index c2853337..39dd0222 100644
--- a/src/app/states.rs
+++ b/src/app/states.rs
@@ -174,6 +174,9 @@ impl ProcessSearchState {
 pub struct ColumnInfo {
     pub enabled: bool,
     pub shortcut: Option<&'static str>,
+    // FIXME: Move column width logic here!
+    // pub hard_width: Option<u16>,
+    // pub max_soft_width: Option<f64>,
 }
 
 pub struct ProcColumn {
@@ -205,6 +208,7 @@ impl Default for ProcColumn {
             WritePerSecond,
             TotalRead,
             TotalWrite,
+            User,
             State,
         ];
 
@@ -219,6 +223,8 @@ impl Default for ProcColumn {
                         ColumnInfo {
                             enabled: true,
                             shortcut: Some("c"),
+                            // hard_width: None,
+                            // max_soft_width: None,
                         },
                     );
                 }
@@ -228,6 +234,8 @@ impl Default for ProcColumn {
                         ColumnInfo {
                             enabled: true,
                             shortcut: Some("m"),
+                            // hard_width: None,
+                            // max_soft_width: None,
                         },
                     );
                 }
@@ -237,6 +245,8 @@ impl Default for ProcColumn {
                         ColumnInfo {
                             enabled: false,
                             shortcut: Some("m"),
+                            // hard_width: None,
+                            // max_soft_width: None,
                         },
                     );
                 }
@@ -246,6 +256,8 @@ impl Default for ProcColumn {
                         ColumnInfo {
                             enabled: true,
                             shortcut: Some("n"),
+                            // hard_width: None,
+                            // max_soft_width: None,
                         },
                     );
                 }
@@ -255,6 +267,8 @@ impl Default for ProcColumn {
                         ColumnInfo {
                             enabled: false,
                             shortcut: Some("n"),
+                            // hard_width: None,
+                            // max_soft_width: None,
                         },
                     );
                 }
@@ -264,6 +278,8 @@ impl Default for ProcColumn {
                         ColumnInfo {
                             enabled: true,
                             shortcut: Some("p"),
+                            // hard_width: None,
+                            // max_soft_width: None,
                         },
                     );
                 }
@@ -273,6 +289,17 @@ impl Default for ProcColumn {
                         ColumnInfo {
                             enabled: false,
                             shortcut: None,
+                            // hard_width: None,
+                            // max_soft_width: None,
+                        },
+                    );
+                }
+                User => {
+                    column_mapping.insert(
+                        column,
+                        ColumnInfo {
+                            enabled: cfg!(target_family = "unix"),
+                            shortcut: None,
                         },
                     );
                 }
@@ -282,6 +309,8 @@ impl Default for ProcColumn {
                         ColumnInfo {
                             enabled: true,
                             shortcut: None,
+                            // hard_width: None,
+                            // max_soft_width: None,
                         },
                     );
                 }
@@ -316,6 +345,33 @@ impl ProcColumn {
         }
     }
 
+    pub fn try_set(&mut self, column: &ProcessSorting, setting: bool) -> Option<bool> {
+        if let Some(mapping) = self.column_mapping.get_mut(column) {
+            mapping.enabled = setting;
+            Some(mapping.enabled)
+        } else {
+            None
+        }
+    }
+
+    pub fn try_enable(&mut self, column: &ProcessSorting) -> Option<bool> {
+        if let Some(mapping) = self.column_mapping.get_mut(column) {
+            mapping.enabled = true;
+            Some(mapping.enabled)
+        } else {
+            None
+        }
+    }
+
+    pub fn try_disable(&mut self, column: &ProcessSorting) -> Option<bool> {
+        if let Some(mapping) = self.column_mapping.get_mut(column) {
+            mapping.enabled = false;
+            Some(mapping.enabled)
+        } else {
+            None
+        }
+    }
+
     pub fn is_enabled(&self, column: &ProcessSorting) -> bool {
         if let Some(mapping) = self.column_mapping.get(column) {
             mapping.enabled
diff --git a/src/canvas/widgets/process_table.rs b/src/canvas/widgets/process_table.rs
index 316e71ae..2abab933 100644
--- a/src/canvas/widgets/process_table.rs
+++ b/src/canvas/widgets/process_table.rs
@@ -30,6 +30,8 @@ static PROCESS_HEADERS_HARD_WIDTH_NO_GROUP: Lazy<Vec<Option<u16>>> = Lazy::new(|
         Some(8),
         Some(7),
         Some(8),
+        #[cfg(target_family = "unix")]
+        None,
         None,
     ]
 });
@@ -48,8 +50,6 @@ static PROCESS_HEADERS_HARD_WIDTH_GROUPED: Lazy<Vec<Option<u16>>> = Lazy::new(||
 
 static PROCESS_HEADERS_SOFT_WIDTH_MAX_GROUPED_COMMAND: Lazy<Vec<Option<f64>>> =
     Lazy::new(|| vec![None, Some(0.7), None, None, None, None, None, None]);
-static PROCESS_HEADERS_SOFT_WIDTH_MAX_GROUPED_TREE: Lazy<Vec<Option<f64>>> =
-    Lazy::new(|| vec![None, Some(0.5), None, None, None, None, None, None]);
 static PROCESS_HEADERS_SOFT_WIDTH_MAX_GROUPED_ELSE: Lazy<Vec<Option<f64>>> =
     Lazy::new(|| vec![None, Some(0.3), None, None, None, None, None, None]);
 
@@ -63,6 +63,8 @@ static PROCESS_HEADERS_SOFT_WIDTH_MAX_NO_GROUP_COMMAND: Lazy<Vec<Option<f64>>> =
         None,
         None,
         None,
+        #[cfg(target_family = "unix")]
+        Some(0.05),
         Some(0.2),
     ]
 });
@@ -76,6 +78,8 @@ static PROCESS_HEADERS_SOFT_WIDTH_MAX_NO_GROUP_TREE: Lazy<Vec<Option<f64>>> = La
         None,
         None,
         None,
+        #[cfg(target_family = "unix")]
+        Some(0.05),
         Some(0.2),
     ]
 });
@@ -89,6 +93,8 @@ static PROCESS_HEADERS_SOFT_WIDTH_MAX_NO_GROUP_ELSE: Lazy<Vec<Option<f64>>> = La
         None,
         None,
         None,
+        #[cfg(target_family = "unix")]
+        Some(0.05),
         Some(0.2),
     ]
 });
@@ -344,6 +350,7 @@ impl ProcessTableWidget for Painter {
                 );
 
                 // Calculate widths
+                // FIXME: See if we can move this into the recalculate block?  I want to move column widths into the column widths
                 let hard_widths = if proc_widget_state.is_grouped {
                     &*PROCESS_HEADERS_HARD_WIDTH_GROUPED
                 } else {
@@ -394,10 +401,10 @@ impl ProcessTableWidget for Painter {
                         .collect::<Vec<_>>();
 
                     let soft_widths_max = if proc_widget_state.is_grouped {
+                        // Note grouped trees are not a thing.
+
                         if proc_widget_state.is_using_command {
                             &*PROCESS_HEADERS_SOFT_WIDTH_MAX_GROUPED_COMMAND
-                        } else if proc_widget_state.is_tree_mode {
-                            &*PROCESS_HEADERS_SOFT_WIDTH_MAX_GROUPED_TREE
                         } else {
                             &*PROCESS_HEADERS_SOFT_WIDTH_MAX_GROUPED_ELSE
                         }
@@ -601,6 +608,7 @@ impl ProcessTableWidget for Painter {
             }
         }
 
+        // TODO: Make the cursor scroll back if there's space!
         if let Some(proc_widget_state) =
             app_state.proc_state.widget_states.get_mut(&(widget_id - 1))
         {
diff --git a/src/constants.rs b/src/constants.rs
index 38c5ef6a..fa6d4b6c 100644
--- a/src/constants.rs
+++ b/src/constants.rs
@@ -272,7 +272,7 @@ pub const PROCESS_HELP_TEXT: [&str; 15] = [
     "click on header  Sorts the entries by that column, click again to invert the sort",
 ];
 
-pub const SEARCH_HELP_TEXT: [&str; 48] = [
+pub const SEARCH_HELP_TEXT: [&str; 49] = [
     "4 - Process search widget",
     "Tab              Toggle between searching for PID and name",
     "Esc              Close the search widget (retains the filter)",
@@ -299,6 +299,7 @@ pub const SEARCH_HELP_TEXT: [&str; 48] = [
     "write, w/s       ex: write <= 1 tb",
     "tread, t.read    ex: tread = 1",
     "twrite, t.write  ex: twrite = 1",
+    "user            ex: user = root",
     "state            ex: state = running",
     "",
     "Comparison operators:",
diff --git a/src/data_conversion.rs b/src/data_conversion.rs
index b3614cf1..c3665cda 100644
--- a/src/data_conversion.rs
+++ b/src/data_conversion.rs
@@ -62,6 +62,7 @@ pub struct ConvertedProcessData {
     pub tw_f64: f64,
     pub process_state: String,
     pub process_char: char,
+    pub user: Option<String>,
 
     /// Prefix printed before the process when displayed.
     pub process_description_prefix: Option<String>,
@@ -482,6 +483,7 @@ pub enum ProcessNamingType {
 pub fn convert_process_data(
     current_data: &data_farmer::DataCollection,
     existing_converted_process_data: &mut HashMap<Pid, ConvertedProcessData>,
+    #[cfg(target_family = "unix")] user_table: &mut data_harvester::processes::UserTable,
 ) {
     // TODO [THREAD]: Thread highlighting and hiding support
     // For macOS see https://github.com/hishamhm/htop/pull/848/files
@@ -503,6 +505,21 @@ pub fn convert_process_data(
             0, converted_total_write.0, converted_total_write.1
         );
 
+        let user = {
+            #[cfg(target_family = "unix")]
+            {
+                if let Some(uid) = process.uid {
+                    user_table.get_uid_to_username_mapping(uid).ok()
+                } else {
+                    None
+                }
+            }
+            #[cfg(not(target_family = "unix"))]
+            {
+                None
+            }
+        };
+
         if let Some(process_entry) = existing_converted_process_data.get_mut(&process.pid) {
             complete_pid_set.remove(&process.pid);
 
@@ -527,6 +544,7 @@ pub fn convert_process_data(
                 process_entry.process_char = process.process_state_char;
                 process_entry.process_description_prefix = None;
                 process_entry.is_disabled_entry = false;
+                process_entry.user = user;
             } else {
                 // ...I hate that I can't combine if let and an if statement in one line...
                 *process_entry = ConvertedProcessData {
@@ -553,6 +571,7 @@ pub fn convert_process_data(
                     process_description_prefix: None,
                     is_disabled_entry: false,
                     is_collapsed_entry: false,
+                    user,
                 };
             }
         } else {
@@ -582,6 +601,7 @@ pub fn convert_process_data(
                     process_description_prefix: None,
                     is_disabled_entry: false,
                     is_collapsed_entry: false,
+                    user,
                 },
             );
         }
@@ -827,8 +847,18 @@ pub fn tree_process_data(
                     is_sort_descending,
                 )
             }),
+            ProcessSorting::User => to_sort_vec.sort_by(|a, b| match (&a.1.user, &b.1.user) {
+                (Some(user_a), Some(user_b)) => utils::gen_util::get_ordering(
+                    user_a.to_lowercase(),
+                    user_b.to_lowercase(),
+                    is_sort_descending,
+                ),
+                (Some(_), None) => std::cmp::Ordering::Less,
+                (None, Some(_)) => std::cmp::Ordering::Greater,
+                (None, None) => std::cmp::Ordering::Less,
+            }),
             ProcessSorting::Count => {
-                // Should never occur in this case.
+                // Should never occur in this case, tree mode explicitly disables grouping.
             }
         }
     }
@@ -990,6 +1020,15 @@ pub fn stringify_process_data(
                     (process.write_per_sec.clone(), None),
                     (process.total_read.clone(), None),
                     (process.total_write.clone(), None),
+                    #[cfg(target_family = "unix")]
+                    (
+                        if let Some(user) = &process.user {
+                            user.clone()
+                        } else {
+                            "N/A".to_string()
+                        },
+                        None,
+                    ),
                     (
                         process.process_state.clone(),
                         Some(process.process_char.to_string()),
@@ -1083,6 +1122,7 @@ pub fn group_process_data(
                 process_char: char::default(),
                 is_disabled_entry: false,
                 is_collapsed_entry: false,
+                user: None,
             }
         })
         .collect::<Vec<_>>()
diff --git a/src/lib.rs b/src/lib.rs
index f5e73a27..e3be6823 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -369,6 +369,8 @@ fn update_final_process_list(app: &mut App, widget_id: u64) {
             convert_process_data(
                 &app.data_collection,
                 &mut app.canvas_data.single_process_data,
+                #[cfg(target_family = "unix")]
+                &mut app.user_table,
             );
         }
         let process_filter = app.get_process_filter(widget_id);
@@ -550,6 +552,16 @@ fn sort_process_data(
                 to_sort_vec.reverse();
             }
         }
+        ProcessSorting::User => to_sort_vec.sort_by(|a, b| match (&a.user, &b.user) {
+            (Some(user_a), Some(user_b)) => utils::gen_util::get_ordering(
+                user_a.to_lowercase(),
+                user_b.to_lowercase(),
+                proc_widget_state.is_process_sort_descending,
+            ),
+            (Some(_), None) => std::cmp::Ordering::Less,
+            (None, Some(_)) => std::cmp::Ordering::Greater,
+            (None, None) => std::cmp::Ordering::Less,
+        }),
         ProcessSorting::Count => {
             if proc_widget_state.is_grouped {
                 to_sort_vec.sort_by(|a, b| {
diff --git a/src/utils/error.rs b/src/utils/error.rs
index f0a965b0..1fc75bd7 100644
--- a/src/utils/error.rs
+++ b/src/utils/error.rs
@@ -86,6 +86,12 @@ impl From<std::str::Utf8Error> for BottomError {
     }
 }
 
+impl From<std::string::FromUtf8Error> for BottomError {
+    fn from(err: std::string::FromUtf8Error) -> Self {
+        BottomError::ConversionError(err.to_string())
+    }
+}
+
 impl From<regex::Error> for BottomError {
     fn from(err: regex::Error) -> Self {
         // We only really want the last part of it... so we'll do it the ugly way: