feat: add option for custom shell

doc/nfm.5

@@ -107,6 +107,13 @@ Colours can be configured individually in the \fBcolours\fR section.
 Defaults to default.
 .RE
 .
+.P
+\fBshell\fR = <shell command>;
+.RS
+The shell command used to execute commands. Defaults to /bin/sh -c.
+The value is treated as space-separated argv for the shell.
+Must be an absolut path, no $PATH-lookups are performed.
+.RE
 .
 .SH SECTION: keybinds
 .P

src/Config.zig

@@ -347,6 +347,7 @@ size_format: SizeFormat = .iec,
 navmode: NavMode = .descend,
 mouse_support: bool = false,
 theme: Theme = themes.default,
+shell: []const [:0]const u8 = &.{ "/bin/sh", "-c" },
 
 pub fn init(self: *Self) !void {
     // This arena will hold all configuration values. Note that we don't need
@@ -587,6 +588,37 @@ fn assignMain(self: *Self, variable: []const u8, value: []const u8, path: []cons
         }
         log.err("{s}:{}: Unknown theme: '{s}'", .{ path, line, value });
         return error.BadConfig;
+    } else if (mem.eql(u8, variable, "shell")) {
+        // We do simple split-based parsing of the arguments here, this should be good
+        // enough for the shell command. This employs an appraoch where the split is performed
+        // twice to count the number of elements for allocation.
+
+        // count args
+        var arg_count: usize = 0;
+        {
+            var iter = mem.tokenize(u8, value, " ");
+            while (iter.next()) |_| {
+                arg_count += 1;
+            }
+        }
+
+        if (arg_count == 0 or arg_count > 32) {
+            log.err("{s}:{}: 'shell' option must not be empty or have more than 32 arguments", .{ path, line });
+            return error.BadConfig;
+        }
+
+        const args = try arena.alloc([:0]const u8, arg_count);
+
+        // collect args
+        {
+            var iter = mem.tokenize(u8, value, " ");
+            var i: usize = 0;
+            while (iter.next()) |arg| : (i += 1) {
+                args[i] = try arena.dupeZ(u8, arg);
+            }
+        }
+
+        self.shell = args;
     } else {
         // TODO maybe try to find the closes approximation and recommend it to the user?
         log.err("{s}:{}: No variable '{s}' in section 'main'", .{ path, line, variable });

src/Context.zig

@@ -212,7 +212,7 @@ pub fn run(self: *Self, command: [:0]const u8, comptime name: []const u8) !void
 
     try self.ui.stop();
 
-    const ret = system.execForeground(command);
+    const ret = system.execForeground(self.config.shell, command);
 
     self.titlebar.setNormal();
     try self.ui.start();
@@ -253,7 +253,7 @@ pub fn open(self: *Self, dir: []const u8, file: []const u8) !void {
     }
     const cmd = try fmt.allocPrintZ(self.alloc, "{s} \"{s}/{s}\"", .{ self.config.opener.?, dir, file });
     defer self.alloc.free(cmd);
-    try system.execBackground(cmd);
+    try system.execBackground(self.config.shell, cmd);
 }
 
 /// Return the name of the item currently selected with the cursor, if any.
@@ -556,11 +556,11 @@ fn handleReturnUserInput(self: *Self) !void {
         .command => {
             if (self.titlebar.getSelectedHistoryItem()) |cmd| {
                 try self.titlebar.appendHistoryItem(cmd);
-                try self.run(cmd, "/bin/sh or subprocess");
+                try self.run(cmd, "shell or subprocess");
             } else if (user_input.buffer.toOwnedSliceZ()) |cmd| {
                 defer self.alloc.free(cmd);
                 try self.titlebar.appendHistoryItem(cmd);
-                try self.run(cmd, "/bin/sh or subprocess");
+                try self.run(cmd, "shell or subprocess");
             }
         },
         .search, .select, .keep, .discard => {

src/key-operations/misc.zig

@@ -86,9 +86,9 @@ fn run(op: *const KeyOperation, foreground: bool) !void {
     const cmd = (try getFormattedBuffer(op)) orelse return;
     defer context.alloc.free(cmd);
     if (foreground) {
-        try context.run(cmd, "/bin/sh or subprocess");
+        try context.run(cmd, "shell or subprocess");
     } else {
-        try system.execBackground(cmd);
+        try system.execBackground(context.config.shell, cmd);
     }
 }
 

src/system/posix.zig

@@ -71,14 +71,19 @@ fn handleSigWinch(_: c_int) callconv(.C) void {
     context.ui.render() catch {};
 }
 
-/// Wrapper around a single fork exec of /bin/sh. Will wait until the forked
+/// Wrapper around a single fork exec of the given shell. Will wait until the forked
 /// process terminates before returning.
-pub fn execForeground(cmd: [:0]const u8) !void {
+pub fn execForeground(shell: []const [:0]const u8, cmd: [:0]const u8) !void {
     log.debug("running foreground command: '{s}'", .{cmd});
-    const args = [_:null]?[*:0]const u8{ "/bin/sh", "-c", cmd, null };
+    var args = [_:null]?[*:0]const u8{null} ** 64;
+
+    for (shell, 0..) |arg , i|
+        args[i] = arg.ptr;
+    args[shell.len] = cmd.ptr;
+
     const pid = std.posix.fork() catch try std.posix.fork();
     if (pid == 0) {
-        std.posix.execveZ("/bin/sh", &args, @as([*:null]?[*:0]u8, @ptrCast(os.environ.ptr))) catch std.posix.exit(1);
+        std.posix.execveZ(shell[0].ptr, &args, @as([*:null]?[*:0]u8, @ptrCast(os.environ.ptr))) catch std.posix.exit(1);
         unreachable;
     } else {
         child_pid = pid;
@@ -93,10 +98,14 @@ pub fn execForeground(cmd: [:0]const u8) !void {
     }
 }
 
-/// Wrapper around a daemonized exec of /bin/sh.
-pub fn execBackground(cmd: [:0]const u8) !void {
+/// Wrapper around a daemonized exec of the given shell.
+pub fn execBackground(shell: []const [:0]const u8, cmd: [:0]const u8) !void {
     log.debug("running background command: '{s}'", .{cmd});
-    const args = [_:null]?[*:0]const u8{ "/bin/sh", "-c", cmd, null };
+    var args = [_:null]?[*:0]const u8{null} ** 64;
+
+    for (shell, 0..) |arg, i| 
+        args[i] = arg.ptr;
+    args[shell.len] = cmd;
 
     // Create first child.
     const pid = std.posix.fork() catch try std.posix.fork();
@@ -124,7 +133,7 @@ pub fn execBackground(cmd: [:0]const u8) !void {
             }
 
             // Execute the command, or die should we fail.
-            std.posix.execveZ("/bin/sh", &args, @as([*:null]?[*:0]u8, @ptrCast(os.environ.ptr))) catch std.posix.exit(1);
+            std.posix.execveZ(shell[0].ptr, &args, @as([*:null]?[*:0]u8, @ptrCast(os.environ.ptr))) catch std.posix.exit(1);
             unreachable;
         } else {
             // Exit first child immediately.