Some documentation in libipc.h, size_t for buffer sizes.

libipc.h

@@ -3,6 +3,7 @@
 
 #include <stdint.h>
 
+// Event types: the "t" parameter in "ipc_wait_event".
 enum event_types {
 	  ERROR         = 0  // A problem occured.
 	, CONNECTION    = 1  // New user.
@@ -23,27 +24,64 @@ enum cb_event_types {
 	, CB_IGNORE     = 3  // The message should be ignored (protocol specific).
 };
 
-int ipc_context_init (void** ptr);
+int ipc_context_init    (void** ptr);  // Allocate memory for a context.
+void ipc_context_deinit (void** ctx);  // Free the context's memory.
+void ipc_context_timer  (void* ctx, int timer); // Change the timer (for timer events, in ms).
+
+// Init (or connect to) a service. That's almost the same operation behind the scene.
 int ipc_service_init    (void* ctx, int* servicefd, const char* service_name, uint16_t service_name_len);
 int ipc_connect_service (void* ctx, int* servicefd, const char* service_name, uint16_t service_name_len);
-void ipc_context_deinit (void** ctx);
+
-int ipc_write (void* ctx, int servicefd, char* mcontent, uint32_t mlen);
+// Write a message or schedule it.
-int ipc_schedule (void* ctx, int servicefd, const char* mcontent, uint32_t mlen);
+int ipc_write    (void* ctx, int servicefd, const char* mcontent, size_t mlen);
+int ipc_schedule (void* ctx, int servicefd, const char* mcontent, size_t mlen);
+
+// Read a message from a client; either selected by an index in the context structure or by its file descriptor.
 int ipc_read_fd (void* ctx,       int fd, char* buffer, size_t* buflen);
 int ipc_read    (void* ctx, size_t index, char* buffer, size_t* buflen);
+
+// Wait for an event.
+// The "t" parameter is the type of the event (enum event_types).
+// The "index" parameter is the index in the context structure of the origin of the event (client or server).
+// The "originfd" parameter is the file descriptor on which the event occurs.
+// The "newfd" parameter is the file descriptor of the new connected client, in case of a connection event.
+// The "buffer" and "buflen" parameters contain respectively a copy of the received message and its length.
 int ipc_wait_event (void* ctx, char* t, size_t* index, int* originfd, int* newfd, char* buffer, size_t* buflen);
-void ipc_context_timer (void* ctx, int timer);
+
+// Close a client (or server) based on its file descriptor or its index in the context structure.
 int ipc_close_fd  (void* ctx,       int fd);
 int ipc_close     (void* ctx, size_t index);
+// Close all connections (probably right before the processus is terminated).
 int ipc_close_all (void* ctx);
 
-// Switch functions (for "protocol" services, such as TCPd).
+// Add a (possibly non-IPC) file descriptor to handle.
+// Since it's not marked as an IPC connection, messages won't be automatically read;
+// which enables to handle any communications for most protocols through the LibIPC API.
 int ipc_add_external (void* ctx, int newfd);
+
+/**
+ * SWITCH: enables the automatic exchange of messages between a pair of file descriptors.
+ *
+ * There are two operations available:
+ * - ipc_add_switch: add a new switch;
+ * - ipc_set_switch_callbacks: set callbacks (IO operations) for a file descriptor,
+ *   enabling specific processing for a connection.
+ *
+ * Callbacks enable to handle non-IPC communications, for example a websocket connection,
+ * a non-IPC client communicating with JSON messages (or any other format), etc.
+ *
+ * Switch and IO callbacks enable to easily create "protocol IPC services" (such as TCPd) to
+ * bind IPC services to basically any available protocol through small, dedicated services
+ * handling all the nitty-gritty details of non-IPC protocols.
+ */
+// Add a new switch between a pair of file descriptors, enabling automatic exchange of messages
+// between this pair of fds. Useful for "protocol services", such as TCPd.
 int ipc_add_switch (void* ctx, int fd1, int fd2);
 
+// Set IO callbacks for a file descriptor.
 // Returned "char" is a cb_event_types enum.
 int ipc_set_switch_callbacks (void* ctx, int fd
-  , char (*in (int orig, const char *payload, uint32_t *mlen))
+  , char (*in (int orig,       char *payload, size_t *mlen))
-  , char (*out(int dest,       char *payload, uint32_t  mlen)));
+  , char (*out(int dest, const char *payload, size_t  mlen)));
 
 #endif

src/bindings.zig

@@ -36,7 +36,7 @@ export fn ipc_context_deinit(ctx: **Context) callconv(.C) void {
 }
 
 /// Write a message (no waiting).
-export fn ipc_write(ctx: *Context, servicefd: i32, mcontent: [*]const u8, mlen: u32) callconv(.C) i32 {
+export fn ipc_write(ctx: *Context, servicefd: i32, mcontent: [*]const u8, mlen: usize) callconv(.C) i32 {
     // TODO: better default length.
     var buffer = [_]u8{0} ** 100000;
     var fba = std.heap.FixedBufferAllocator.init(&buffer);
@@ -48,7 +48,7 @@ export fn ipc_write(ctx: *Context, servicefd: i32, mcontent: [*]const u8, mlen:
 
 /// Schedule a message.
 /// Use the same allocator as the context.
-export fn ipc_schedule(ctx: *Context, servicefd: i32, mcontent: [*]const u8, mlen: u32) callconv(.C) i32 {
+export fn ipc_schedule(ctx: *Context, servicefd: i32, mcontent: [*]const u8, mlen: usize) callconv(.C) i32 {
     const message = Message.init(servicefd, ctx.allocator, mcontent[0..mlen]) catch return -1;
     ctx.schedule(message) catch return -2;
     return 0;
@@ -152,8 +152,8 @@ export fn ipc_add_switch(ctx: *Context, fd1: i32, fd2: i32) callconv(.C) i32 {
 }
 
 export fn ipc_set_switch_callbacks(ctx: *Context, fd: i32,
-                                   in: *const fn (origin: i32, mcontent: [*]u8, mlen: *u32) callconv(.C) u8,
+        in: *const fn (origin: i32, mcontent: [*]u8, mlen: *usize) callconv(.C) u8,
-                                   out: *const fn (origin: i32, mcontent: [*]const u8, mlen: u32) callconv(.C) u8) callconv(.C) i32 {
+        out: *const fn (origin: i32, mcontent: [*]const u8, mlen: usize) callconv(.C) u8) callconv(.C) i32 {
     ctx.set_switch_callbacks(fd, in, out) catch return -1;
     return 0;
 }

src/context.zig

@@ -317,8 +317,8 @@ pub const Context = struct {
     }
 
     pub fn set_switch_callbacks(self: *Self, fd: i32,
-                                in: *const fn (origin: i32, mcontent: [*]u8, mlen: *u32) callconv(.C) u8,
+            in:  *const fn (origin: i32, mcontent:       [*]u8, mlen: *usize) callconv(.C) u8,
-                                out: *const fn (origin: i32, mcontent: [*]const u8, mlen: u32) callconv(.C) u8) !void {
+            out: *const fn (origin: i32, mcontent: [*]const u8, mlen:  usize) callconv(.C) u8) !void {
         try self.switchdb.set_callbacks(fd, in, out);
     }
 

src/switch.zig

@@ -65,8 +65,8 @@ pub const SwitchDB = struct {
     }
 
     pub fn set_callbacks(self: *Self, fd: i32,
-                         in: *const fn (origin: i32, mcontent: [*]u8, mlen: *u32) callconv(.C) u8,
+            in: *const fn (origin: i32, mcontent: [*]u8, mlen: *usize) callconv(.C) u8,
-                         out: *const fn (origin: i32, mcontent: [*]const u8, mlen: u32) callconv(.C) u8) !void {
+            out: *const fn (origin: i32, mcontent: [*]const u8, mlen: usize) callconv(.C) u8) !void {
         var managedconnection = self.db.get(fd) orelse return error.unregisteredFD;
         managedconnection.in = in;
         managedconnection.out = out;
@@ -80,7 +80,7 @@ pub const SwitchDB = struct {
         var managedconnection = self.db.get(fd) orelse return error.unregisteredFD;
 
         var buffer = [_]u8{0} ** 100000; // TODO: buffer size
-        var message_size: u32 = @truncate(buffer.len);
+        var message_size: usize = buffer.len;
         const r: CBEventType = @enumFromInt(managedconnection.in(fd, &buffer, &message_size));
 
         switch (r) {
@@ -124,7 +124,7 @@ pub const SwitchDB = struct {
         _ = message.write(writer) catch return error.generic;
         const written = fbs.getWritten();
 
-        const r: CBEventType = @enumFromInt(managedconnection.out(message.fd, written.ptr, @truncate(written.len)));
+        const r: CBEventType = @enumFromInt(managedconnection.out(message.fd, written.ptr, written.len));
 
         switch (r) {
             // The message should be ignored (protocol specific).
@@ -186,8 +186,8 @@ pub const SwitchDB = struct {
 
 const ManagedConnection = struct {
     dest: i32,
-    in: *const fn (origin: i32, mcontent: [*]u8, mlen: *u32) callconv(.C) u8 = default_in,
+    in:  *const fn (origin: i32, mcontent:       [*]u8, mlen: *usize) callconv(.C) u8 = default_in,
-    out: *const fn (origin: i32, mcontent: [*]const u8, mlen: u32) callconv(.C) u8 = default_out,
+    out: *const fn (origin: i32, mcontent: [*]const u8, mlen:  usize) callconv(.C) u8 = default_out,
 };
 
 test "creation and display" {
@@ -205,18 +205,18 @@ test "creation and display" {
     try print_eq("{ (5,6)(6,5) }", .{switchdb});
 }
 
-fn successful_in(_: i32, mcontent: [*]u8, mlen: *u32) CBEventType {
+fn successful_in(_: i32, mcontent: [*]u8, mlen: *usize) CBEventType {
     var m = Message.init(8, std.heap.c_allocator, "coucou") catch unreachable;
     defer m.deinit();
 
     var fbs = std.io.fixedBufferStream(mcontent[0..mlen.*]);
     const writer = fbs.writer();
     const bytes_written = m.write(writer) catch unreachable;
-    mlen.* = @truncate(bytes_written);
+    mlen.* = bytes_written;
     return CBEventType.NO_ERROR;
 }
 
-fn successful_out(_: i32, _: [*]const u8, _: u32) CBEventType {
+fn successful_out(_: i32, _: [*]const u8, _: usize) CBEventType {
     return CBEventType.NO_ERROR;
 }
 
@@ -255,11 +255,11 @@ test "successful exchanges" {
     }
 }
 
-fn unsuccessful_in(_: i32, _: [*]const u8, _: *u32) CBEventType {
+fn unsuccessful_in(_: i32, _: [*]const u8, _: *usize) CBEventType {
     return CBEventType.ERROR;
 }
 
-fn unsuccessful_out(_: i32, _: [*]const u8, _: u32) CBEventType {
+fn unsuccessful_out(_: i32, _: [*]const u8, _: usize) CBEventType {
     return CBEventType.ERROR;
 }
 
@@ -311,7 +311,7 @@ test "nuke 'em" {
     try testing.expect(switchdb.db.count() == 0);
 }
 
-fn default_in(origin: i32, mcontent: [*]u8, mlen: *u32) callconv(.C) u8 {
+fn default_in(origin: i32, mcontent: [*]u8, mlen: *usize) callconv(.C) u8 {
     // This may be kinda hacky, idk.
     var stream: net.Stream = .{ .handle = origin };
     const packet_size: usize = stream.read(mcontent[0..mlen.*]) catch return @intFromEnum(CBEventType.ERROR);
@@ -322,12 +322,12 @@ fn default_in(origin: i32, mcontent: [*]u8, mlen: *u32) callconv(.C) u8 {
         return @intFromEnum(CBEventType.FD_CLOSING);
     }
 
-    mlen.* = @truncate(packet_size);
+    mlen.* = packet_size;
 
     return @intFromEnum(CBEventType.NO_ERROR);
 }
 
-fn default_out(fd: i32, mcontent: [*]const u8, mlen: u32) callconv(.C) u8 {
+fn default_out(fd: i32, mcontent: [*]const u8, mlen: usize) callconv(.C) u8 {
     // Message contains the fd, no need to search for the right structure to copy,
     // let's just recreate a Stream from the fd.