Expand ~ and ~user in config file

Fixes #243

src/c.zig

@@ -9,6 +9,9 @@ pub const c = @cImport({
     @cInclude("wchar.h"); // wcwidth()
     @cInclude("locale.h"); // setlocale() and localeconv()
     @cInclude("fnmatch.h"); // fnmatch()
+    @cInclude("unistd.h"); // getuid()
+    @cInclude("sys/types.h"); // struct passwd
+    @cInclude("pwd.h"); // getpwnam(), getpwuid()
     if (@import("builtin").os.tag == .linux) {
         @cInclude("sys/vfs.h"); // statfs()
     }

src/main.zig

@@ -194,7 +194,7 @@ const Args = struct {
     }
 };
 
-fn argConfig(args: *Args, opt: Args.Option) bool {
+fn argConfig(args: *Args, opt: Args.Option, infile: bool) bool {
     if (opt.is("-q") or opt.is("--slow-ui-updates")) config.update_delay = 2*std.time.ns_per_s
     else if (opt.is("--fast-ui-updates")) config.update_delay = 100*std.time.ns_per_ms
     else if (opt.is("-x") or opt.is("--one-file-system")) config.same_fs = true
@@ -270,9 +270,13 @@ fn argConfig(args: *Args, opt: Args.Option) bool {
     else if (opt.is("--no-si")) config.si = false
     else if (opt.is("-L") or opt.is("--follow-symlinks")) config.follow_symlinks = true
     else if (opt.is("--no-follow-symlinks")) config.follow_symlinks = false
-    else if (opt.is("--exclude")) exclude.addPattern(args.arg())
+    else if (opt.is("--exclude")) {
-    else if (opt.is("-X") or opt.is("--exclude-from")) {
+        const arg = if (infile) (util.expanduser(args.arg(), allocator) catch unreachable) else args.arg();
-        const arg = args.arg();
+        defer if (infile) allocator.free(arg);
+        exclude.addPattern(arg);
+    } else if (opt.is("-X") or opt.is("--exclude-from")) {
+        const arg = if (infile) (util.expanduser(args.arg(), allocator) catch unreachable) else args.arg();
+        defer if (infile) allocator.free(arg);
         readExcludeFile(arg) catch |e| ui.die("Error reading excludes from {s}: {s}.\n", .{ arg, ui.errorString(e) });
     } else if (opt.is("--exclude-caches")) config.exclude_caches = true
     else if (opt.is("--include-caches")) config.exclude_caches = false
@@ -341,7 +345,7 @@ fn tryReadArgsFile(path: [:0]const u8) void {
 
     var args = Args.init(arglist.items);
     while (args.next()) |opt| {
-        if (!argConfig(&args, opt))
+        if (!argConfig(&args, opt, true))
             ui.die("Unrecognized option in config file '{s}': {s}.\nRun with --ignore-config to skip reading config files.\n", .{path, opt.val});
     }
     for (arglist.items) |i| allocator.free(i);
@@ -540,7 +544,7 @@ pub fn main() void {
             else if (opt.is("-f")) import_file = allocator.dupeZ(u8, args.arg()) catch unreachable
             else if (opt.is("--ignore-config")) {}
             else if (opt.is("--quit-after-scan")) quit_after_scan = true // undocumented feature to help with benchmarking scan/import
-            else if (argConfig(&args, opt)) {}
+            else if (argConfig(&args, opt, false)) {}
             else ui.die("Unrecognized option '{s}'.\n", .{opt.val});
         }
     }

src/util.zig

@@ -2,6 +2,7 @@
 // SPDX-License-Identifier: MIT
 
 const std = @import("std");
+const c = @import("c.zig").c;
 
 // Cast any integer type to the target type, clamping the value to the supported maximum if necessary.
 pub fn castClamp(comptime T: type, x: anytype) T {
@@ -170,3 +171,30 @@ test "strnatcmp" {
         for (i+1..w.len) |j| try eq(strnatcmp(w[i], w[j]), .lt);
     }
 }
+
+
+pub fn expanduser(path: []const u8, alloc: std.mem.Allocator) ![:0]u8 {
+    if (path.len == 0 or path[0] != '~') return alloc.dupeZ(u8, path);
+
+    const len = std.mem.indexOfScalar(u8, path, '/') orelse path.len;
+    const home_raw = blk: {
+        const pwd = pwd: {
+            if (len == 1) {
+                if (std.posix.getenvZ("HOME")) |p| break :blk p;
+                break :pwd c.getpwuid(c.getuid());
+            } else {
+                const name = try alloc.dupeZ(u8, path[1..len]);
+                defer alloc.free(name);
+                break :pwd c.getpwnam(name.ptr);
+            }
+        };
+        if (pwd != null)
+            if (@as(*c.struct_passwd, pwd).pw_dir) |p|
+                break :blk std.mem.span(p);
+        return alloc.dupeZ(u8, path);
+    };
+    const home = std.mem.trimRight(u8, home_raw, "/");
+
+    if (home.len == 0 and path.len == len) return alloc.dupeZ(u8, "/");
+    return try std.fmt.allocPrintZ(alloc, "{s}{s}", .{ home, path[len..] });
+}