Add script/print-json-token-debug-format.c
diff --git a/script/print-json-token-debug-format.c b/script/print-json-token-debug-format.c
new file mode 100644
index 0000000..851e513
--- /dev/null
+++ b/script/print-json-token-debug-format.c
@@ -0,0 +1,210 @@
+// Copyright 2020 The Wuffs Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// ----------------
+
+// print-json-token-debug-format.c parses JSON from stdin and prints the
+// resulting token stream, eliding any non-essential (e.g. whitespace) tokens.
+//
+// The output format is only for debugging, and certainly not for long term
+// storage. It isn't guaranteed to be stable between versions of this program
+// and of the Wuffs standard library.
+//
+// It prints 16 bytes (4 big-endian uint32's) per token: the token's position
+// (total length of all previous tokens), length, major value and minor value.
+// Together with the hexadecimal WUFFS_BASE__TOKEN__ETC constants defined in
+// token-public.h, this format is somewhat human-readable when piped through a
+// hex-dump program (e.g. /usr/bin/hd).
+//
+// If the input or output is larger than the program's buffers (64 MiB and
+// 131072 tokens by default), there may be multiple valid tokenizations of any
+// given input. For example, if a source string "abcde" straddles an I/O
+// boundary, it may be tokenized as a 5-length complete string or as a 3-length
+// incomplete string followed by a 2-length complete string.
+//
+// A Wuffs token stream, in general, can support inputs more than (1 << 32)
+// bytes long, but this program can not, as it tracks the tokens' cumulative
+// position as a uint32.
+
+#include <inttypes.h>
+#include <stdio.h>
+#include <string.h>
+#include <unistd.h>
+
+// Wuffs ships as a "single file C library" or "header file library" as per
+// https://github.com/nothings/stb/blob/master/docs/stb_howto.txt
+//
+// To use that single file as a "foo.c"-like implementation, instead of a
+// "foo.h"-like header, #define WUFFS_IMPLEMENTATION before #include'ing or
+// compiling it.
+#define WUFFS_IMPLEMENTATION
+
+// Defining the WUFFS_CONFIG__MODULE* macros are optional, but it lets users of
+// release/c/etc.c whitelist which parts of Wuffs to build. That file contains
+// the entire Wuffs standard library, implementing a variety of codecs and file
+// formats. Without this macro definition, an optimizing compiler or linker may
+// very well discard Wuffs code for unused codecs, but listing the Wuffs
+// modules we use makes that process explicit. Preprocessing means that such
+// code simply isn't compiled.
+#define WUFFS_CONFIG__MODULES
+#define WUFFS_CONFIG__MODULE__BASE
+#define WUFFS_CONFIG__MODULE__JSON
+
+// If building this program in an environment that doesn't easily accommodate
+// relative includes, you can use the script/inline-c-relative-includes.go
+// program to generate a stand-alone C++ file.
+#include "../release/c/wuffs-unsupported-snapshot.c"
+
+#ifndef SRC_BUFFER_SIZE
+#define SRC_BUFFER_SIZE (64 * 1024 * 1024)
+#endif
+#ifndef TOKEN_BUFFER_SIZE
+#define TOKEN_BUFFER_SIZE (128 * 1024)
+#endif
+
+uint8_t src_buffer[SRC_BUFFER_SIZE];
+wuffs_base__token tok_buffer[TOKEN_BUFFER_SIZE];
+
+wuffs_base__io_buffer src;
+wuffs_base__token_buffer tok;
+
+wuffs_json__decoder dec;
+wuffs_base__status dec_status;
+
+static inline void //
+store_u32be(uint8_t* p, uint32_t x) {
+ p[0] = (uint8_t)(x >> 24);
+ p[1] = (uint8_t)(x >> 16);
+ p[2] = (uint8_t)(x >> 8);
+ p[3] = (uint8_t)(x >> 0);
+}
+
+#define TRY(error_msg) \
+ do { \
+ const char* z = error_msg; \
+ if (z) { \
+ return z; \
+ } \
+ } while (false)
+
+const char* //
+read_src() {
+ if (src.meta.closed) {
+ return "main: internal error: read requested on a closed source";
+ }
+ wuffs_base__io_buffer__compact(&src);
+ if (src.meta.wi >= src.data.len) {
+ return "main: src buffer is full";
+ }
+ size_t n = fread(src.data.ptr + src.meta.wi, sizeof(uint8_t),
+ src.data.len - src.meta.wi, stdin);
+ src.meta.wi += n;
+ src.meta.closed = feof(stdin);
+ if ((n == 0) && !src.meta.closed) {
+ return "main: read error";
+ }
+ return NULL;
+}
+
+// ----
+
+const char* //
+main1(int argc, char** argv) {
+ src = wuffs_base__make_io_buffer(
+ wuffs_base__make_slice_u8(src_buffer, SRC_BUFFER_SIZE),
+ wuffs_base__empty_io_buffer_meta());
+
+ tok = wuffs_base__make_token_buffer(
+ wuffs_base__make_slice_token(tok_buffer, TOKEN_BUFFER_SIZE),
+ wuffs_base__empty_token_buffer_meta());
+
+ wuffs_base__status init_status = wuffs_json__decoder__initialize(
+ &dec, sizeof__wuffs_json__decoder(), WUFFS_VERSION, 0);
+ if (!wuffs_base__status__is_ok(&init_status)) {
+ return wuffs_base__status__message(&init_status);
+ }
+
+ uint64_t pos = 0;
+ while (true) {
+ wuffs_base__status status =
+ wuffs_json__decoder__decode_tokens(&dec, &tok, &src);
+
+ while (tok.meta.ri < tok.meta.wi) {
+ wuffs_base__token* t = &tok.data.ptr[tok.meta.ri++];
+ uint64_t len = wuffs_base__token__length(t);
+
+ if (wuffs_base__token__value(t) != 0) {
+ uint64_t major = wuffs_base__token__value_major(t);
+ uint64_t minor = wuffs_base__token__value_minor(t);
+
+ uint8_t buf[16];
+ store_u32be(&buf[0 * 4], (uint32_t)(pos));
+ store_u32be(&buf[1 * 4], (uint32_t)(len));
+ store_u32be(&buf[2 * 4], (uint32_t)(major));
+ store_u32be(&buf[3 * 4], (uint32_t)(minor));
+ const int stdout_fd = 1;
+ write(stdout_fd, &buf[0], 16);
+ }
+
+ pos += len;
+ if (pos > 0xFFFFFFFF) {
+ return "main: input is too long";
+ }
+ }
+
+ if (status.repr == NULL) {
+ return NULL;
+ } else if (status.repr == wuffs_base__suspension__short_read) {
+ TRY(read_src());
+ } else if (status.repr == wuffs_base__suspension__short_write) {
+ wuffs_base__token_buffer__compact(&tok);
+ } else {
+ return wuffs_base__status__message(&status);
+ }
+ }
+}
+
+// ----
+
+int //
+compute_exit_code(const char* status_msg) {
+ if (!status_msg) {
+ return 0;
+ }
+ size_t n = strnlen(status_msg, 2047);
+ if (n >= 2047) {
+ status_msg = "main: internal error: error message is too long";
+ n = strnlen(status_msg, 2047);
+ }
+ fprintf(stderr, "%s\n", status_msg);
+ // Return an exit code of 1 for regular (forseen) errors, e.g. badly
+ // formatted or unsupported input.
+ //
+ // Return an exit code of 2 for internal (exceptional) errors, e.g. defensive
+ // run-time checks found that an internal invariant did not hold.
+ //
+ // Automated testing, including badly formatted inputs, can therefore
+ // discriminate between expected failure (exit code 1) and unexpected failure
+ // (other non-zero exit codes). Specifically, exit code 2 for internal
+ // invariant violation, exit code 139 (which is 128 + SIGSEGV on x86_64
+ // linux) for a segmentation fault (e.g. null pointer dereference).
+ return strstr(status_msg, "internal error:") ? 2 : 1;
+}
+
+int //
+main(int argc, char** argv) {
+ const char* z = main1(argc, argv);
+ int exit_code = compute_exit_code(z);
+ return exit_code;
+}