feat: support any writer (#33)

Author: jiacai2050

README.org

@@ -1,6 +1,6 @@
 #+TITLE: zig-curl
 #+DATE: 2023-09-16T23:16:15+0800
-#+LASTMOD: 2025-07-27T20:02:08+0800
+#+LASTMOD: 2025-08-02T11:33:35+0800
 #+OPTIONS: toc:nil num:nil
 #+STARTUP: content
 
@@ -44,13 +44,15 @@ pub fn main() !void {
     });
     defer easy.deinit();
 
-    var ctx = curl.ResizableWriteContext.init(allocator);
-    defer ctx.deinit();
-    const resp = try easy.fetch("https://httpbin.org/anything", .{}, &ctx);
+    var writer = curl.ResizableResponseWriter.init(allocator);
+    defer writer.deinit();
+    const resp = try easy.fetch("https://httpbin.org/anything", .{
+        .response_writer = writer.asAny(),
+    });
 
     std.debug.print("Status code: {d}\nBody: {s}\n", .{
         resp.status_code,
-        ctx.asSlice(),
+        writer.asSlice(),
     });
 }
 #+end_src

examples/advanced.zig

@@ -41,20 +41,20 @@ fn putWithCustomHeader(allocator: Allocator, easy: Easy) !void {
     try easy.setVerbose(true);
     try easy.setPostFields(body);
 
-    var writeContext = curl.ResizableWriteContext.init(allocator);
-    defer writeContext.deinit();
-    try easy.setWriteContext(&writeContext, curl.ResizableWriteContext.write);
+    var writer = curl.ResizableResponseWriter.init(allocator);
+    defer writer.deinit();
+    try easy.setAnyWriter(&writer.asAny());
 
     const resp = try easy.perform();
     std.debug.print("Status code: {d}\nBody: {s}\n", .{
         resp.status_code,
-        writeContext.asSlice(),
+        writer.asSlice(),
     });
 
     const parsed = try std.json.parseFromSlice(
         Response,
         allocator,
-        writeContext.asSlice(),
+        writer.asSlice(),
         .{ .ignore_unknown_fields = true },
     );
     defer parsed.deinit();
@@ -103,12 +103,12 @@ fn postMultiPart(allocator: Allocator, easy: Easy) !void {
     try easy.setMultiPart(multi_part);
     try easy.setVerbose(true);
 
-    var writeContext = curl.ResizableWriteContext.init(allocator);
-    defer writeContext.deinit();
-    try easy.setWriteContext(&writeContext, curl.ResizableWriteContext.write);
+    var writer = curl.ResizableResponseWriter.init(allocator);
+    defer writer.deinit();
+    try easy.setAnyWriter(&writer.asAny());
 
     const resp = try easy.perform();
-    std.debug.print("code: {d}, resp:{s}\n", .{ resp.status_code, writeContext.asSlice() });
+    std.debug.print("code: {d}, resp:{s}\n", .{ resp.status_code, writer.asSlice() });
 }
 
 pub fn main() !void {

examples/basic.zig

@@ -10,19 +10,21 @@ const LOCAL_SERVER_ADDR = "http://localhost:8182";
 fn get(easy: Easy) !void {
     {
         println("GET without write context");
-        const resp = try easy.fetch("https://httpbin.org/anything", .{}, {});
+        const resp = try easy.fetch("https://httpbin.org/anything", .{});
 
         std.debug.print("Status code: {d}\n", .{resp.status_code});
     }
 
     {
         println("GET with fixed buffer");
         var buffer: [1024]u8 = undefined;
-        var writeContext = curl.FixedWriteContext.init(&buffer);
-        const resp = try easy.fetch("https://httpbin.org/anything", .{}, &writeContext);
+        var writer = curl.FixedResponseWriter.init(&buffer);
+        const resp = try easy.fetch("https://httpbin.org/anything", .{
+            .response_writer = writer.asAny(),
+        });
         std.debug.print("Status code: {d}\nBody: {s}\n", .{
             resp.status_code,
-            writeContext.asSlice(),
+            writer.asSlice(),
         });
     }
 }
@@ -31,8 +33,8 @@ fn post(allocator: Allocator, easy: Easy) !void {
     const payload =
         \\{"name": "John", "age": 15}
     ;
-    var writeContext = curl.ResizableWriteContext.init(allocator);
-    defer writeContext.deinit();
+    var writer = curl.ResizableResponseWriter.init(allocator);
+    defer writer.deinit();
     const resp = try easy.fetch(
         "https://httpbin.org/anything",
         .{
@@ -41,26 +43,26 @@ fn post(allocator: Allocator, easy: Easy) !void {
             .headers = &.{
                 "Content-Type: application/json",
             },
+            .response_writer = writer.asAny(),
         },
-        &writeContext,
     );
 
     std.debug.print("Status code: {d}\nBody: {s}\n", .{
         resp.status_code,
-        writeContext.asSlice(),
+        writer.asSlice(),
     });
 }
 
 fn upload(allocator: Allocator, easy: Easy) !void {
     const path = "LICENSE";
-    var writeContext = curl.ResizableWriteContext.init(allocator);
-    defer writeContext.deinit();
+    var writer = curl.ResizableResponseWriter.init(allocator);
+    defer writer.deinit();
 
-    const resp = try easy.upload(LOCAL_SERVER_ADDR ++ "/anything", path, &writeContext);
+    const resp = try easy.upload(LOCAL_SERVER_ADDR ++ "/anything", path, writer.asAny());
 
     std.debug.print("Status code: {d}\nBody: {s}\n", .{
         resp.status_code,
-        writeContext.asSlice(),
+        writer.asSlice(),
     });
 }
 

examples/header.zig

@@ -7,7 +7,7 @@ fn iterateHeaders(easy: Easy) !void {
     // Reset old options, e.g. headers.
     easy.reset();
 
-    const resp = try easy.fetch("https://httpbin.org/response-headers?X-Foo=1&X-Foo=2&X-Foo=3", .{}, {});
+    const resp = try easy.fetch("https://httpbin.org/response-headers?X-Foo=1&X-Foo=2&X-Foo=3", .{});
 
     std.debug.print("Iterating all headers...\n", .{});
     {
@@ -31,7 +31,7 @@ fn iterateHeaders(easy: Easy) !void {
 
 fn iterateRedirectedHeaders(easy: Easy) !void {
     try easy.setFollowLocation(true);
-    const resp = try easy.fetch("https://httpbin.org/redirect/1", .{}, {});
+    const resp = try easy.fetch("https://httpbin.org/redirect/1", .{});
 
     const redirects = try resp.getRedirectCount();
     try std.testing.expectEqual(redirects, 1);

examples/hello.zig

@@ -13,12 +13,14 @@ pub fn main() !void {
     });
     defer easy.deinit();
 
-    var ctx = curl.ResizableWriteContext.init(allocator);
-    defer ctx.deinit();
-    const resp = try easy.fetch("https://httpbin.org/anything", .{}, &ctx);
+    var writer = curl.ResizableResponseWriter.init(allocator);
+    defer writer.deinit();
+    const resp = try easy.fetch("https://httpbin.org/anything", .{
+        .response_writer = writer.asAny(),
+    });
 
     std.debug.print("Status code: {d}\nBody: {s}\n", .{
         resp.status_code,
-        ctx.asSlice(),
+        writer.asSlice(),
     });
 }

examples/multi.zig

@@ -7,14 +7,15 @@ const Easy = curl.Easy;
 const Multi = curl.Multi;
 const c = curl.libcurl;
 const checkCode = curl.checkCode;
+const AnyWriter = std.io.AnyWriter;
 
-fn newEasy(ctx: *curl.ResizableWriteContext, url: [:0]const u8) !Easy {
+fn newEasy(writer: *curl.ResizableResponseWriter, any_writer: *const AnyWriter, url: [:0]const u8) !Easy {
     const easy = try Easy.init(.{});
     try easy.setUrl(url);
-    try easy.setWriteContext(ctx, curl.ResizableWriteContext.write);
+    try easy.setAnyWriter(any_writer);
     // CURLOPT_PRIVATE allows us to store a pointer to the ctx in the easy handle
     // so we can retrieve it later in the callback.
-    try easy.setPrivate(ctx);
+    try easy.setPrivate(writer);
 
     return easy;
 }
@@ -27,13 +28,15 @@ pub fn main() !void {
     const multi = try Multi.init();
     defer multi.deinit();
 
-    var ctx1 = curl.ResizableWriteContext.init(allocator);
-    defer ctx1.deinit();
-    var ctx2 = curl.ResizableWriteContext.init(allocator);
-    defer ctx2.deinit();
+    var wtr1 = curl.ResizableResponseWriter.init(allocator);
+    defer wtr1.deinit();
+    const any_writer1: AnyWriter = wtr1.asAny();
+    var wtr2 = curl.ResizableResponseWriter.init(allocator);
+    defer wtr2.deinit();
+    const any_writer2: AnyWriter = wtr2.asAny();
 
-    try multi.addHandle(try newEasy(&ctx1, "http://httpbin.org/headers"));
-    try multi.addHandle(try newEasy(&ctx2, "http://httpbin.org/ip"));
+    try multi.addHandle(try newEasy(&wtr1, &any_writer1, "http://httpbin.org/headers"));
+    try multi.addHandle(try newEasy(&wtr2, &any_writer2, "http://httpbin.org/ip"));
 
     var keep_running = true;
     while (keep_running) {
@@ -69,8 +72,8 @@ pub fn main() !void {
         // Get the private data (buffer) associated with this handle
         var private_data: ?*anyopaque = null;
         try checkCode(c.curl_easy_getinfo(easy_handle, c.CURLINFO_PRIVATE, &private_data));
-        const ctx: *curl.ResizableWriteContext = @ptrCast(@alignCast(private_data.?));
+        const writer: *curl.ResizableResponseWriter = @ptrCast(@alignCast(private_data.?));
 
-        std.debug.print("Response body: {s}\n", .{ctx.asSlice()});
+        std.debug.print("Response body: {s}\n", .{writer.asSlice()});
     }
 }

src/Easy.zig

@@ -1,13 +1,15 @@
 const std = @import("std");
 const errors = @import("errors.zig");
 const util = @import("util.zig");
+const types = @import("types.zig");
 const c = util.c;
 
 const mem = std.mem;
 const fmt = std.fmt;
+const AnyWriter = std.io.AnyWriter;
 const Allocator = mem.Allocator;
 const checkCode = errors.checkCode;
-const ResizableBuffer = util.ResizableBuffer;
+const ResizableBuffer = types.ResizableBuffer;
 
 const hasParseHeaderSupport = @import("util.zig").hasParseHeaderSupport;
 
@@ -52,6 +54,7 @@ pub const FetchOptions = struct {
     method: Method = .GET,
     body: ?[]const u8 = null,
     headers: ?[]const [:0]const u8 = null,
+    response_writer: ?AnyWriter = null,
 };
 
 pub const Response = struct {
@@ -338,11 +341,11 @@ pub fn setUnixSocketPath(self: Self, path: [:0]const u8) !void {
     try checkCode(c.curl_easy_setopt(self.handle, c.CURLOPT_UNIX_SOCKET_PATH, path.ptr));
 }
 
-pub fn setPrivate(self: Self, data: *anyopaque) !void {
+pub fn setPrivate(self: Self, data: *const anyopaque) !void {
     try checkCode(c.curl_easy_setopt(self.handle, c.CURLOPT_PRIVATE, data));
 }
 
-pub fn setWritedata(self: Self, data: *anyopaque) !void {
+pub fn setWritedata(self: Self, data: *const anyopaque) !void {
     try checkCode(c.curl_easy_setopt(self.handle, c.CURLOPT_WRITEDATA, data));
 }
 
@@ -360,19 +363,21 @@ pub fn setWritefunction(
     try checkCode(c.curl_easy_setopt(self.handle, c.CURLOPT_WRITEFUNCTION, func));
 }
 
-/// Set `WRITEDATA` to context and `WRITEFUNCTION` to a function that calls with the context.
-pub fn setWriteContext(
+/// Set `WRITEDATA` to AnyWriter and `WRITEFUNCTION` to a function that calls with the writer.
+pub fn setAnyWriter(
     self: Self,
-    context: anytype,
-    comptime writeFunc: fn (@TypeOf(context), ptr: []const u8) usize,
+    any_writer: *const AnyWriter,
 ) !void {
-    try self.setWritedata(context);
+    try self.setWritedata(any_writer);
     try self.setWritefunction(struct {
         fn write(ptr: [*c]c_char, size: c_uint, nmemb: c_uint, user_data: *anyopaque) callconv(.C) c_uint {
             const real_size = size * nmemb;
-            const ctx: @TypeOf(context) = @alignCast(@ptrCast(user_data));
             const data = (@as([*]const u8, @ptrCast(ptr)))[0..real_size];
-            return @intCast(writeFunc(ctx, data));
+            const writer: *const AnyWriter = @alignCast(@ptrCast(user_data));
+            const ret = writer.write(data) catch {
+                return 0; // Indicate an error
+            };
+            return @intCast(ret);
         }
     }.write);
 }
@@ -426,25 +431,6 @@ pub fn perform(self: Self) !Response {
     };
 }
 
-fn setWriteContextInner(self: Self, context: anytype) !void {
-    const ctxType = @typeInfo(@TypeOf(context));
-    switch (ctxType) {
-        .void => {
-            // No write context, do nothing.
-            return;
-        },
-        .pointer => |ptr| {
-            if (comptime !@hasDecl(ptr.child, "write")) {
-                @compileError("writeContext must have a `write` function");
-            }
-            try self.setWriteContext(context, @field(ptr.child, "write"));
-        },
-        else => {
-            @compileError("writeContext must be a pointer or void type, current: " ++ @typeName(@TypeOf(context)));
-        },
-    }
-}
-
 /// Head issues a HEAD to the specified URL.
 pub fn head(self: Self, url: [:0]const u8) !Response {
     try self.setUrl(url);
@@ -463,7 +449,6 @@ pub fn fetch(
     self: Self,
     url: [:0]const u8,
     options: FetchOptions,
-    writeContext: anytype,
 ) !Response {
     try self.setUrl(url);
     try self.setMethod(options.method);
@@ -483,20 +468,22 @@ pub fn fetch(
         h.deinit();
     };
 
-    try self.setWriteContextInner(writeContext);
+    if (options.response_writer) |writer| {
+        try self.setAnyWriter(&writer);
+    }
 
     return try self.perform();
 }
 
 /// Upload issues a PUT request to upload file.
 /// `writeContext` is the same as in `fetch`, used to write the response body.
-pub fn upload(self: Self, url: [:0]const u8, path: []const u8, writeContext: anytype) !Response {
+pub fn upload(self: Self, url: [:0]const u8, path: []const u8, any_writer: AnyWriter) !Response {
     var up = try Upload.init(path);
     defer up.deinit();
     try self.setUpload(&up);
 
     try self.setUrl(url);
-    try self.setWriteContextInner(writeContext);
+    try self.setAnyWriter(&any_writer);
     return try self.perform();
 }
 

src/root.zig

@@ -1,11 +1,12 @@
 const std = @import("std");
 const util = @import("util.zig");
+const types = @import("types.zig");
 pub const checkCode = @import("errors.zig").checkCode;
 
 pub const Easy = @import("Easy.zig");
 pub const Multi = @import("Multi.zig");
-pub const ResizableWriteContext = util.ResizableWriteContext;
-pub const FixedWriteContext = util.FixedWriteContext;
+pub const ResizableResponseWriter = types.ResizableResponseWriter;
+pub const FixedResponseWriter = types.FixedResponseWriter;
 
 pub const printLibcurlVersion = util.printLibcurlVersion;
 pub const hasParseHeaderSupport = util.hasParseHeaderSupport;