Tests: Add a fuzz test program and a config file for OSS-Fuzz.
Thanks to Bhargava Shastry and Github user pdknsk.
diff --git a/tests/Makefile.am b/tests/Makefile.am
index 86084e1..4116b81 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -7,6 +7,7 @@
EXTRA_DIST = \
files \
+ ossfuzz \
tests.h \
test_files.sh \
test_compress.sh \
diff --git a/tests/ossfuzz/Makefile b/tests/ossfuzz/Makefile
new file mode 100644
index 0000000..67ddbe5
--- /dev/null
+++ b/tests/ossfuzz/Makefile
@@ -0,0 +1,7 @@
+fuzz: fuzz.c
+ $(CC) $(CFLAGS) -c fuzz.c -I ../../src/liblzma/api/
+ $(CXX) $(CXXFLAGS) -lFuzzingEngine fuzz.o -o $(OUT)/fuzz \
+ ../../src/liblzma/.libs/liblzma.a
+
+clean:
+ rm -f *.o
diff --git a/tests/ossfuzz/config/fuzz.dict b/tests/ossfuzz/config/fuzz.dict
new file mode 100644
index 0000000..932d67c
--- /dev/null
+++ b/tests/ossfuzz/config/fuzz.dict
@@ -0,0 +1,2 @@
+"\xFD7zXZ\x00"
+"YZ"
diff --git a/tests/ossfuzz/config/fuzz.options b/tests/ossfuzz/config/fuzz.options
new file mode 100644
index 0000000..d59dfc1
--- /dev/null
+++ b/tests/ossfuzz/config/fuzz.options
@@ -0,0 +1,2 @@
+[libfuzzer]
+dict = fuzz.dict
diff --git a/tests/ossfuzz/fuzz.c b/tests/ossfuzz/fuzz.c
new file mode 100644
index 0000000..6d89930
--- /dev/null
+++ b/tests/ossfuzz/fuzz.c
@@ -0,0 +1,82 @@
+///////////////////////////////////////////////////////////////////////////////
+//
+/// \file fuzz.c
+/// \brief Fuzz test program for liblzma
+//
+// Author: Lasse Collin
+//
+// This file has been put into the public domain.
+// You can do whatever you want with this file.
+//
+///////////////////////////////////////////////////////////////////////////////
+
+#include <inttypes.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include "lzma.h"
+
+
+// Output buffer for decompressed data. This is write only; nothing cares
+// about the actual data written here.
+static uint8_t outbuf[4096];
+
+
+extern int
+LLVMFuzzerTestOneInput(const uint8_t *inbuf, size_t inbuf_size)
+{
+ // Some header values can make liblzma allocate a lot of RAM
+ // (up to about 4 GiB with liblzma 5.2.x). We set a limit here to
+ // prevent extreme allocations when fuzzing.
+ const uint64_t memlimit = 300 << 20; // 300 MiB
+
+ // Initialize a .xz decoder using the above memory usage limit.
+ // Enable support for concatenated .xz files which is used when
+ // decompressing regular .xz files (instead of data embedded inside
+ // some other file format). Integrity checks on the uncompressed
+ // data are ignored to make fuzzing more effective (incorrect check
+ // values won't prevent the decoder from processing more input).
+ //
+ // The flag LZMA_IGNORE_CHECK doesn't disable verification of header
+ // CRC32 values. Those checks are disabled when liblzma is built
+ // with the #define FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION.
+ lzma_stream strm = LZMA_STREAM_INIT;
+ lzma_ret ret = lzma_stream_decoder(&strm, memlimit,
+ LZMA_CONCATENATED | LZMA_IGNORE_CHECK);
+ if (ret != LZMA_OK) {
+ // This should never happen unless the system has
+ // no free memory or address space to allow the small
+ // allocations that the initialization requires.
+ fprintf(stderr, "lzma_stream_decoder() failed (%d)\n", ret);
+ abort();
+ }
+
+ // Give the whole input buffer at once to liblzma.
+ // Output buffer isn't initialized as liblzma only writes to it.
+ strm.next_in = inbuf;
+ strm.avail_in = inbuf_size;
+ strm.next_out = outbuf;
+ strm.avail_out = sizeof(outbuf);
+
+ while ((ret = lzma_code(&strm, LZMA_FINISH)) == LZMA_OK) {
+ if (strm.avail_out == 0) {
+ // outbuf became full. We don't care about the
+ // uncompressed data there, so we simply reuse
+ // the outbuf and overwrite the old data.
+ strm.next_out = outbuf;
+ strm.avail_out = sizeof(outbuf);
+ }
+ }
+
+ // LZMA_PROG_ERROR should never happen as long as the code calling
+ // the liblzma functions is correct. Thus LZMA_PROG_ERROR is a sign
+ // of a bug in either this function or in liblzma.
+ if (ret == LZMA_PROG_ERROR) {
+ fprintf(stderr, "lzma_code() returned LZMA_PROG_ERROR\n");
+ abort();
+ }
+
+ // Free the allocated memory.
+ lzma_end(&strm);
+
+ return 0;
+}
