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const std = @import("std");
const path = @import("path.zig");
const BUILTINS = [_][]const u8{ "exit", "echo", "type", "pwd", "cd", "history" };
pub const CommandResult = enum { continue_loop, exit_shell };
pub inline fn isBuiltin(cmd_name: []const u8) bool {
inline for (BUILTINS) |builtin| {
if (std.mem.eql(u8, cmd_name, builtin)) return true;
}
return false;
}
pub inline fn executeExit() CommandResult {
return .exit_shell;
}
pub fn executeEcho(stdout: anytype, args: ?[]const u8) !void {
const a = args orelse {
try stdout.print("\n", .{});
return;
};
var buf = std.ArrayList(u8){};
defer buf.deinit(std.heap.page_allocator);
var i: usize = 0;
var in_quote = false;
var quote_char: u8 = 0;
var last_space = false;
while (i < a.len) : (i += 1) {
const c = a[i];
if (!in_quote and c == '\\' and i + 1 < a.len) {
i += 1;
try buf.append(std.heap.page_allocator, a[i]);
last_space = false;
} else if (!in_quote and (c == '\'' or c == '"')) {
in_quote = true;
quote_char = c;
last_space = false;
} else if (in_quote and c == quote_char) {
in_quote = false;
last_space = false;
} else if (in_quote and quote_char == '"' and c == '\\' and i + 1 < a.len) {
const next = a[i + 1];
if (next == '"' or next == '\\') i += 1;
try buf.append(std.heap.page_allocator, a[i]);
last_space = false;
} else if (!in_quote and c == ' ') {
if (!last_space) {
try buf.append(std.heap.page_allocator, ' ');
last_space = true;
}
} else {
try buf.append(std.heap.page_allocator, c);
last_space = false;
}
}
try stdout.print("{s}\n", .{buf.items});
}
pub fn executePwd(allocator: std.mem.Allocator, stdout: anytype) !void {
const cwd = try std.fs.cwd().realpathAlloc(allocator, ".");
defer allocator.free(cwd);
try stdout.print("{s}\n", .{cwd});
}
pub fn executeCd(allocator: std.mem.Allocator, stdout: anytype, args: ?[]const u8) !void {
const a = args orelse {
try stdout.print("cd: missing argument\n", .{});
return;
};
if (a.len == 0) {
try stdout.print("cd: missing argument\n", .{});
return;
}
const arg = std.mem.trim(u8, a, " ");
var path_buf: [512]u8 = undefined;
const dir = blk: {
if (std.mem.eql(u8, arg, "~")) {
const home = std.process.getEnvVarOwned(allocator, "HOME") catch {
try stdout.print("cd: HOME not set\n", .{});
return;
};
defer allocator.free(home);
break :blk try std.fmt.bufPrint(&path_buf, "{s}", .{home});
} else if (std.mem.startsWith(u8, arg, "~/")) {
const home = std.process.getEnvVarOwned(allocator, "HOME") catch {
try stdout.print("cd: HOME not set\n", .{});
return;
};
defer allocator.free(home);
break :blk try std.fmt.bufPrint(&path_buf, "{s}/{s}", .{ home, arg[2..] });
}
break :blk arg;
};
std.posix.chdir(dir) catch {
try stdout.print("cd: {s}: No such file or directory\n", .{arg});
};
}
pub fn executeType(allocator: std.mem.Allocator, stdout: anytype, args: ?[]const u8) !void {
const a = args orelse return;
if (isBuiltin(a)) {
try stdout.print("{s} is a shell builtin\n", .{a});
} else if (try path.findInPath(allocator, a)) |cmd_path| {
defer allocator.free(cmd_path);
try stdout.print("{s} is {s}\n", .{ a, cmd_path });
} else {
try stdout.print("{s}: not found\n", .{a});
}
}
pub fn executeHistory(stdout: anytype, history_list: []const []const u8, args: ?[]const u8) !void {
var limit = history_list.len;
if (args) |a| {
const trimmed = std.mem.trim(u8, a, " ");
if (trimmed.len > 0) {
if (std.mem.startsWith(u8, trimmed, "-r ")) {
return;
}
limit = std.fmt.parseInt(usize, trimmed, 10) catch {
try stdout.print("history: invalid argument\n", .{});
return;
};
}
}
const start = if (limit < history_list.len) history_list.len - limit else 0;
for (history_list[start..], start + 1..) |cmd, idx| {
try stdout.print(" {d} {s}\n", .{ idx, cmd });
}
}
fn readHistoryFile(allocator: std.mem.Allocator, file_path: []const u8, history_list: *std.ArrayList([]const u8)) !void {
const file = try std.fs.cwd().openFile(file_path, .{});
defer file.close();
const file_size = try file.getEndPos();
if (file_size == 0) return;
const buffer = try allocator.alloc(u8, file_size);
defer allocator.free(buffer);
const bytes_read = try file.readAll(buffer);
var line_iter = std.mem.splitScalar(u8, buffer[0..bytes_read], '\n');
while (line_iter.next()) |line| {
const trimmed = std.mem.trim(u8, line, " \r");
if (trimmed.len > 0) {
const line_copy = try allocator.dupe(u8, trimmed);
try history_list.append(allocator, line_copy);
}
}
}
fn writeHistoryFile(file_path: []const u8, history_list: []const []const u8) !void {
const file = try std.fs.cwd().createFile(file_path, .{});
defer file.close();
for (history_list) |cmd| {
try file.writeAll(cmd);
try file.writeAll("\n");
}
}
pub fn executeHistoryRead(allocator: std.mem.Allocator, stdout: anytype, file_path: []const u8, history_list: *std.ArrayList([]const u8)) !void {
readHistoryFile(allocator, file_path, history_list) catch {
try stdout.print("history: cannot open {s}: error\n", .{file_path});
};
}
pub fn executeHistoryWrite(stdout: anytype, file_path: []const u8, history_list: []const []const u8) !void {
writeHistoryFile(file_path, history_list) catch {
try stdout.print("history: cannot write to {s}: error\n", .{file_path});
};
}
pub fn executeHistoryAppend(stdout: anytype, file_path: []const u8, history_list: []const []const u8, last_written_index: *usize) !void {
const file = std.fs.cwd().openFile(file_path, .{ .mode = .write_only }) catch |err| {
if (err == error.FileNotFound) {
writeHistoryFile(file_path, history_list) catch {
try stdout.print("history: cannot write to {s}: error\n", .{file_path});
return;
};
last_written_index.* = history_list.len;
return;
}
try stdout.print("history: cannot open {s}: error\n", .{file_path});
return;
};
defer file.close();
try file.seekFromEnd(0);
for (history_list[last_written_index.*..]) |cmd| {
try file.writeAll(cmd);
try file.writeAll("\n");
}
last_written_index.* = history_list.len;
}
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