w-h/0.2.0: Add an example of a file download

This also shows an example of (at least the best I could figure out) how
to send an error 4xx/5xx response back.

Signed-off-by: Andrew Clayton <a.clayton@nginx.com>

2 files changed, 167 insertions, 0 deletions

diff --git a/c/wasi-http/0.2.0/download-test/Makefile b/c/wasi-http/0.2.0/download-test/Makefile
new file mode 100644
index 0000000..f9e3bfe
--- /dev/null
+++ b/c/wasi-http/0.2.0/download-test/Makefile
@@ -0,0 +1,29 @@
+# Look for wasi-sysroot in some common places, falling back
+# to provided WASI_SYSROOT
+ifneq ("$(wildcard /usr/wasm32-wasi)", "")
+        # Fedora
+        WASI_SYSROOT ?= /usr/wasm32-wasi
+endif
+
+export WASI_SYSROOT
+
+CC      = clang
+CFLAGS  = -Wall -Wextra -g --target=wasm32-wasi --sysroot=$(WASI_SYSROOT)
+LDFLAGS = -Wl,--no-entry,--export=__heap_base,--export=__data_end,--export=malloc,--export=free,--stack-first,-z,stack-size=$$((8*1024*1024)) -mexec-model=reactor --rtlib=compiler-rt
+
+all: component.wasm
+
+bindgen:
+	/home/andrew/src/c/wasm/git/wit-bindgen/target/release/wit-bindgen c /home/andrew/src/c/wasm/git/wasi-http/wit --autodrop-borrows yes --world wasi:http/proxy
+	/home/andrew/src/c/wasm/git/wit-bindgen/target/release/wit-bindgen markdown /home/andrew/src/c/wasm/git/wasi-http/wit --world wasi:http/proxy
+
+.PHONY:
+module.wasm: bindgen
+	$(CC) $(CFLAGS) $(LDFLAGS) -o $@ proxy.c proxy_component_type.o component.c
+
+.PHONY:
+component.wasm: module.wasm
+	/home/andrew/src/c/wasm/git/wasm-tools/target/release/wasm-tools component new module.wasm --adapt ../../adaptors/24.0.0/wasi_snapshot_preview1.reactor.wasm -o component.wasm
+
+clean:
+	rm -f component.wasm module.wasm proxy*
diff --git a/c/wasi-http/0.2.0/download-test/component.c b/c/wasi-http/0.2.0/download-test/component.c
new file mode 100644
index 0000000..78981ed
--- /dev/null
+++ b/c/wasi-http/0.2.0/download-test/component.c
@@ -0,0 +1,138 @@
+/* SPDX-License-Identifier: Apache-2.0 */
+
+/*
+ * component.c - Example of writing a wasi-http Wasm component
+ *
+ * Copyright (C) Andrew Clayton
+ * Copyright (C) F5, Inc.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <string.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <errno.h>
+
+#include "proxy.h"
+
+#define IMG_SZ		(256 * 1024*1024UL)
+
+#define ex(...) \
+	do { \
+		printf(__VA_ARGS__); \
+		exit(EXIT_FAILURE); \
+	} while (0);
+
+void exports_wasi_http_incoming_handler_handle(
+	exports_wasi_http_incoming_handler_own_incoming_request_t request,
+	exports_wasi_http_incoming_handler_own_response_outparam_t response_out)
+{
+	int fd;
+	bool ok;
+	char clen[32];
+	char *buf;
+	wasi_http_types_own_outgoing_response_t resp;
+	wasi_http_types_borrow_outgoing_response_t b_resp;
+	wasi_http_types_own_fields_t fields;
+	wasi_http_types_borrow_fields_t b_fields;
+	wasi_http_types_result_own_outgoing_response_error_code_t rerr = { };
+	wasi_http_types_own_outgoing_body_t body;
+	wasi_http_types_borrow_outgoing_body_t b_body;
+	wasi_io_streams_own_output_stream_t out_stream;
+	wasi_io_streams_borrow_output_stream_t b_out_stream;
+	proxy_list_u8_t stream_data;
+	wasi_io_streams_stream_error_t stream_err;
+	wasi_http_types_header_error_t hdr_err;
+	wasi_http_types_field_key_t key;
+	wasi_http_types_field_value_t value;
+
+	(void)request;
+
+	buf = malloc(IMG_SZ);
+	fd = open("/var/tmp/img", O_RDONLY);
+	if (fd == -1) {
+		wasi_http_types_status_code_t sc;
+
+		printf("E: %s (/var/tmp/img)\n", strerror(errno));
+
+		switch (errno) {
+		case EACCES:
+		case EFAULT:
+		case EPERM:
+			sc = 403;
+			break;
+		case EBADF:
+		case ENAMETOOLONG:
+		case ENODEV:
+		case ENOENT:
+		case ENOTDIR:
+			sc = 404;
+			break;
+		default:
+			sc = 500;
+		}
+
+		fields = wasi_http_types_constructor_fields();
+		resp = wasi_http_types_constructor_outgoing_response(fields);
+		b_resp = wasi_http_types_borrow_outgoing_response(resp);
+		wasi_http_types_method_outgoing_response_set_status_code(b_resp,
+									 sc);
+		rerr.val.ok = resp;
+
+		goto out_response;
+	}
+
+	read(fd, buf, IMG_SZ);
+	close(fd);
+
+	fields = wasi_http_types_constructor_fields();
+	b_fields = wasi_http_types_borrow_fields(fields);
+
+	proxy_string_set((proxy_string_t *)&key, "Content-Type");
+	proxy_string_set((proxy_string_t *)&value, "application/octet-stream");
+
+	ok = wasi_http_types_method_fields_append(b_fields, &key, &value,
+						  &hdr_err);
+	if (!ok)
+		ex("wasi_http_types_method_fields_append(Content-Type) failed\n");
+
+	proxy_string_set((proxy_string_t *)&key, "Content-Length");
+	sprintf(clen, "%zu", IMG_SZ);
+	proxy_string_set((proxy_string_t *)&value, clen);
+
+	ok = wasi_http_types_method_fields_append(b_fields, &key, &value,
+						  &hdr_err);
+	if (!ok)
+		ex("wasi_http_types_method_fields_append(Content-Length) failed\n");
+
+	resp = wasi_http_types_constructor_outgoing_response(fields);
+	rerr.val.ok = resp;
+
+	b_resp = wasi_http_types_borrow_outgoing_response(resp);
+	ok = wasi_http_types_method_outgoing_response_body(b_resp, &body);
+	if (!ok)
+		ex("wasi_http_types_method_outgoing_response_body() failed\n");
+	b_body = wasi_http_types_borrow_outgoing_body(body);
+
+	ok = wasi_http_types_method_outgoing_body_write(b_body, &out_stream);
+	if (!ok)
+		ex("wasi_http_types_method_outgoing_body_write() failed\n");
+	b_out_stream = wasi_io_streams_borrow_output_stream(out_stream);
+
+	stream_data.len = IMG_SZ;
+	stream_data.ptr = (uint8_t *)buf;
+	ok = wasi_io_streams_method_output_stream_write(b_out_stream,
+							&stream_data,
+							&stream_err);
+	if (!ok)
+		ex("wasi_io_streams_method_output_stream_blocking_write_and_flush() failed\n");
+
+out_response:
+
+	wasi_http_types_static_response_outparam_set(response_out, &rerr);
+
+	free(buf);
+}