From 6aa4b01692c47cc63e270a0473f662be59c120cf Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Motiejus=20Jak=C5=A1tys?= <motiejus@jakstys.lt>
Date: Wed, 22 Jun 2022 16:23:02 +0300
Subject: [PATCH] wip handling errors in top level

---
 src/ErrCtx.zig       |  4 ++--
 src/unix2db/main.zig | 38 +++++++++++++++++++++++++-------------
 2 files changed, 27 insertions(+), 15 deletions(-)

diff --git a/src/ErrCtx.zig b/src/ErrCtx.zig
index 4343a3a..da15f70 100644
--- a/src/ErrCtx.zig
+++ b/src/ErrCtx.zig
@@ -22,8 +22,8 @@ pub fn write(self: *ErrCtx, bytes: []const u8) error{}!usize {
 
     self.overflow = bytes.len > can_add;
     self.buf.appendSliceAssumeCapacity(bytes[0..math.min(bytes.len, can_add)]);
-    // not adding the final zero is ok, because it needs
-    // to be ignored in the iterator anyway.
+    // not adding the final zero is ok, because it will
+    // be ignored in the iterator anyway.
     _ = self.buf.append(0) catch null;
 
     return bytes.len;
diff --git a/src/unix2db/main.zig b/src/unix2db/main.zig
index bacaf18..1e2400f 100644
--- a/src/unix2db/main.zig
+++ b/src/unix2db/main.zig
@@ -40,25 +40,25 @@ fn execute(
     allocator: Allocator,
     stderr: anytype,
     argv: []const [*:0]const u8,
-) !u8 {
+) u8 {
     const result = flags.parse(argv, &[_]flags.Flag{
         .{ .name = "-h", .kind = .boolean },
         .{ .name = "--passwd", .kind = .arg },
         .{ .name = "--group", .kind = .arg },
         .{ .name = "--output", .kind = .arg },
     }) catch {
-        try stderr.writeAll(usage);
+        stderr.writeAll(usage) catch {};
         return 1;
     };
 
     if (result.boolFlag("-h")) {
-        try io.getStdOut().writeAll(usage);
+        io.getStdOut().writeAll(usage) catch return 1;
         return 0;
     }
 
     if (result.args.len != 0) {
-        try stderr.print("ERROR: unknown option '{s}'\n", .{result.args[0]});
-        try stderr.writeAll(usage);
+        stderr.print("ERROR: unknown option '{s}'\n", .{result.args[0]}) catch {};
+        stderr.writeAll(usage) catch {};
         return 1;
     }
 
@@ -66,10 +66,20 @@ fn execute(
     const groupFname = result.argFlag("--group") orelse "./group";
     const outFile = result.argFlag("--output") orelse "./db.turbo";
 
-    //std.debug.print("passwd file name: {s}\n", .{passwdFname});
-    var passwdFile = try fs.cwd().openFile(passwdFname, .{ .mode = .read_only });
+    // to catch a specific file.OpenError, wait for
+    // https://github.com/ziglang/zig/issues/2473
+    var passwdFile = fs.cwd().openFile(
+        passwdFname,
+        .{ .mode = .read_only },
+    ) catch |err| {
+        stderr.print("Error opening {s}: {s}\n", .{ passwdFname, @errorName(err) }) catch {};
+        return 1;
+    };
     defer passwdFile.close();
-    var groupFile = try fs.cwd().openFile(groupFname, .{ .mode = .read_only });
+    var groupFile = fs.cwd().openFile(groupFname, .{ .mode = .read_only }) catch |err| {
+        stderr.print("Error opening {s}: {s}\n", .{ groupFname, @errorName(err) }) catch {};
+        return 1;
+    };
     defer groupFile.close();
 
     var err_ctx = ErrCtx{};
@@ -79,9 +89,11 @@ fn execute(
         passwdFile.reader(),
     );
     errdefer {
-        var it = err_ctx.iterator();
+        stderr.print("ERROR", .{}) catch {};
+        var it = err_ctx.rev();
         while (it.next()) |err|
-            std.debug.print("ERROR: {s}\n", .{err});
+            stderr.print(": {s}", .{err}) catch {};
+        stderr.print("\n", .{}) catch {};
     }
     defer for (users) |*user| user.deinit(allocator);
     defer allocator.free(users);
@@ -118,7 +130,7 @@ test "invalid argument" {
     var stderr = ArrayList(u8).init(allocator);
     defer stderr.deinit();
 
-    const exit_code = try execute(allocator, stderr.writer(), args[0..]);
+    const exit_code = execute(allocator, stderr.writer(), args[0..]);
     try testing.expectEqual(@as(u8, 1), exit_code);
     try testing.expect(mem.startsWith(
         u8,
@@ -128,8 +140,6 @@ test "invalid argument" {
 }
 
 test "smoke test" {
-    if (true) return error.SkipZigTest;
-
     const allocator = testing.allocator;
     var stderr = ArrayList(u8).init(allocator);
     defer stderr.deinit();
@@ -181,6 +191,8 @@ test "smoke test" {
         "--group",  groupPath,
         "--output", outPath,
     };
+
+    if (true) return error.SkipZigTest;
     const exit_code = try execute(allocator, stderr.writer(), args);
 
     try testing.expectEqual(@as(u8, 0), exit_code);