Add fuzz/c/std/tga_fuzzer.c

Updates #67
diff --git a/fuzz/c/std/seed_corpora.txt b/fuzz/c/std/seed_corpora.txt
index 01e1767..01fa62f 100644
--- a/fuzz/c/std/seed_corpora.txt
+++ b/fuzz/c/std/seed_corpora.txt
@@ -20,6 +20,7 @@
 gzip:   test/data/*.gz
 json:   test/data/*.json  ../rapidjson_corpus/*  ../simdjson_corpus/*  ../JSONTestSuite/test_*/*.json
 png:    test/data/*.png   test/data/artificial-png/*.png  ../pngsuite_corpus/*.png
+tga:    test/data/*.tga
 wbmp:   test/data/*.wbmp
 zlib:   test/data/*.zlib
 
diff --git a/fuzz/c/std/tga_fuzzer.c b/fuzz/c/std/tga_fuzzer.c
new file mode 100644
index 0000000..b2803c5
--- /dev/null
+++ b/fuzz/c/std/tga_fuzzer.c
@@ -0,0 +1,88 @@
+// 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.
+
+// ----------------
+
+// Silence the nested slash-star warning for the next comment's command line.
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wcomment"
+
+/*
+This fuzzer (the fuzz function) is typically run indirectly, by a framework
+such as https://github.com/google/oss-fuzz calling LLVMFuzzerTestOneInput.
+
+When working on the fuzz implementation, or as a coherence check, defining
+WUFFS_CONFIG__FUZZLIB_MAIN will let you manually run fuzz over a set of files:
+
+gcc -DWUFFS_CONFIG__FUZZLIB_MAIN tga_fuzzer.c
+./a.out ../../../test/data/*.tga
+rm -f ./a.out
+
+It should print "PASS", amongst other information, and exit(0).
+*/
+
+#pragma clang diagnostic pop
+
+// 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
+
+#if defined(WUFFS_CONFIG__FUZZLIB_MAIN)
+// Defining the WUFFS_CONFIG__STATIC_FUNCTIONS macro is optional, but when
+// combined with WUFFS_IMPLEMENTATION, it demonstrates making all of Wuffs'
+// functions have static storage.
+//
+// This can help the compiler ignore or discard unused code, which can produce
+// faster compiles and smaller binaries. Other motivations are discussed in the
+// "ALLOW STATIC IMPLEMENTATION" section of
+// https://raw.githubusercontent.com/nothings/stb/master/docs/stb_howto.txt
+#define WUFFS_CONFIG__STATIC_FUNCTIONS
+#endif  // defined(WUFFS_CONFIG__FUZZLIB_MAIN)
+
+// Defining the WUFFS_CONFIG__MODULE* macros are optional, but it lets users of
+// release/c/etc.c choose 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__TGA
+
+// 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"
+#include "../fuzzlib/fuzzlib.c"
+#include "../fuzzlib/fuzzlib_image_decoder.c"
+
+const char*  //
+fuzz(wuffs_base__io_buffer* src, uint64_t hash) {
+  wuffs_tga__decoder dec;
+  wuffs_base__status status = wuffs_tga__decoder__initialize(
+      &dec, sizeof dec, WUFFS_VERSION,
+      (hash & 1) ? WUFFS_INITIALIZE__LEAVE_INTERNAL_BUFFERS_UNINITIALIZED : 0);
+  hash = wuffs_base__u64__rotate_right(hash, 1);
+  if (!wuffs_base__status__is_ok(&status)) {
+    return wuffs_base__status__message(&status);
+  }
+  return fuzz_image_decoder(
+      src, hash,
+      wuffs_tga__decoder__upcast_as__wuffs_base__image_decoder(&dec));
+}