wasi: add getEnvMap

std/os.zig

@@ -756,6 +756,37 @@ pub fn getEnvMap(allocator: *Allocator) !BufMap {
 
             try result.setMove(key, value);
         }
+    } else if (builtin.os == Os.wasi) {
+        var environ_count: usize = undefined;
+        var environ_buf_size: usize = undefined;
+
+        const environ_sizes_get_ret = std.os.wasi.environ_sizes_get(&environ_count, &environ_buf_size);
+        if (environ_sizes_get_ret != os.wasi.ESUCCESS) {
+            return unexpectedErrorPosix(environ_sizes_get_ret);
+        }
+
+        // TODO: Verify that the documentation is incorrect
+        // https://github.com/WebAssembly/WASI/issues/27
+        var environ = try allocator.alloc(?[*]u8, environ_count + 1);
+        defer allocator.free(environ);
+        var environ_buf = try std.heap.wasm_allocator.alloc(u8, environ_buf_size);
+        defer allocator.free(environ_buf);
+
+        const environ_get_ret = std.os.wasi.environ_get(environ.ptr, environ_buf.ptr);
+        if (environ_get_ret != os.wasi.ESUCCESS) {
+            return unexpectedErrorPosix(environ_get_ret);
+        }
+
+        for (environ) |env| {
+            if (env) |ptr| {
+                const pair = mem.toSlice(u8, ptr);
+                var parts = mem.separate(pair, "=");
+                const key = parts.next().?;
+                const value = parts.next().?;
+                try result.set(key, value);
+            }
+        }
+        return result;
     } else {
         for (posix_environ_raw) |ptr| {
             var line_i: usize = 0;
@@ -2190,7 +2221,7 @@ pub fn argsAlloc(allocator: *mem.Allocator) ![]const []u8 {
         }
 
         var result_slice = try allocator.alloc([]u8, count);
-        
+
         var i: usize = 0;
         while (i < count) : (i += 1) {
             result_slice[i] = mem.toSlice(u8, argv[i]);

std/os/wasi/core.zig

@@ -13,8 +13,10 @@ pub const SIGABRT: signal_t = 6;
 pub extern "wasi_unstable" fn args_get(argv: [*][*]u8, argv_buf: [*]u8) errno_t;
 pub extern "wasi_unstable" fn args_sizes_get(argc: *usize, argv_buf_size: *usize) errno_t;
 
-pub extern "wasi_unstable" fn proc_raise(sig: signal_t) errno_t;
+pub extern "wasi_unstable" fn environ_get(environ: [*]?[*]u8, environ_buf: [*]u8) errno_t;
+pub extern "wasi_unstable" fn environ_sizes_get(environ_count: *usize, environ_buf_size: *usize) errno_t;
 
+pub extern "wasi_unstable" fn proc_raise(sig: signal_t) errno_t;
 pub extern "wasi_unstable" fn proc_exit(rval: exitcode_t) noreturn;
 
 pub extern "wasi_unstable" fn fd_write(fd: fd_t, iovs: *const ciovec_t, iovs_len: usize, nwritten: *usize) errno_t;