zip: read in memory (#10960)

vlib/szip/szip_test.v

@@ -4,8 +4,10 @@ import os
 const (
 	test_out_zip = 'v_test_zip.zip'
 	test_path    = 'zip files'
-	fpath1       = os.join_path(test_path, 'file_1.txt')
-	fpath2       = os.join_path(test_path, 'file_2.txt')
+	fname1       = 'file_1.txt'
+	fpath1       = os.join_path(test_path, fname1)
+	fname2       = 'file_2.txt'
+	fpath2       = os.join_path(test_path, fname2)
 )
 
 fn test_szip_create_temp_files() ? {
@@ -35,3 +37,52 @@ fn test_extract_zipped_files() ? {
 	os.rmdir_all(test_path) ?
 	os.rm(test_out_zip) or {}
 }
+
+fn test_reading_zipping_files() ? {
+	n_files := 2
+	mut file_name_list := []string{}
+	for i in 0 .. n_files {
+		file_name_list << 'file_${i:02}.txt'
+	}
+
+	os.chdir(os.temp_dir())
+	os.rmdir_all(test_path) or {}
+	os.mkdir(test_path) ?
+	for c, f_name in file_name_list {
+		tmp_path := os.join_path(test_path, f_name)
+		os.write_file(tmp_path, 'file ${c:02}') ?
+		assert os.exists(tmp_path)
+	}
+	files := (os.ls(test_path) ?).map(os.join_path(test_path, it))
+
+	szip.zip_files(files, test_out_zip) ?
+	assert os.exists(test_out_zip)
+
+	mut zp := szip.open(test_out_zip, szip.CompressionLevel.no_compression, szip.OpenMode.read_only) ?
+	n_entries := zp.total() ?
+	assert n_entries == n_files
+
+	unsafe {
+		data_len := 'file XX'.len
+		buf_size := 32
+		buf := malloc(data_len * 2)
+
+		for _ in 0 .. n_files {
+			zp.open_entry_by_index(0) ?
+			name := zp.name()
+			assert name in file_name_list
+
+			zp.read_entry_buf(buf, buf_size) ?
+			buf[data_len] = 0
+			tmp_str := tos(buf, data_len)
+
+			assert tmp_str[0..4] == 'file'
+			assert tmp_str[5..7] == name[5..7]
+
+			zp.close_entry()
+		}
+
+		free(buf)
+	}
+	zp.close()
+}