Merge pull request #10 from pmembrey/master

snappy should be able to decompress an empty binary
skunkwerks · Jan 6, 2015 · 1d29d69 · 1d29d69
2 parents 868243b + 73f2014
commit 1d29d69
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diff --git a/c_src/snappy_nif.cc b/c_src/snappy_nif.cc
@@ -143,6 +143,16 @@ snappy_compress_erl(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
         return enif_make_badarg(env);
     }
 
+    // If empty binary has been provided, return an empty binary.
+    // Snappy will do this in any case, so might as well skip the
+    // overhead...
+    if(input.size == 0) {
+        ErlNifBinary empty;
+        // init empty;
+        memset(&empty,0,sizeof(ErlNifBinary));
+        return make_ok(env, enif_make_binary(env,&empty));
+     }
+
     try {
         snappy::ByteArraySource source(SC_PTR(input.data), input.size);
         SnappyNifSink sink(env);
@@ -167,6 +177,15 @@ snappy_decompress_erl(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
         return enif_make_badarg(env);
     }
 
+    // Check that the binary is not empty
+    if(bin.size == 0) {
+        // Snappy library cannot decompress an empty binary - although
+        // it will unfortunately let you compress one. If an empty binary
+        // has been passed - send an empty binary back.
+        memset(&ret,0,sizeof(ErlNifBinary));
+        return make_ok(env, enif_make_binary(env,&ret));
+    }
+
     try {
         if(!snappy::GetUncompressedLength(SC_PTR(bin.data), bin.size, &len)) {
             return make_error(env, "data_not_compressed");

diff --git a/test/snappy_tests.erl b/test/snappy_tests.erl
@@ -72,3 +72,36 @@ decompression() ->
     ?assertEqual({ok, BigData}, snappy:decompress(Compressed3)),
     ok.
 
+check_double_decompress_doesnt_cause_segault_test() ->
+    % Try to decompress an empty binary
+    ?assertMatch({ok,<<>>}, snappy:decompress(<<>>)),
+    % And once more...
+    ?assertMatch({ok,<<>>}, snappy:decompress(<<>>)),
+    ok.
+
+check_double_compress_doesnt_cause_segault_test() ->
+    % Try to compress an empty binary
+    ?assertMatch({ok,<<>>},snappy:compress(<<>>)),
+    % And once more...
+    ?assertMatch({ok,<<>>},snappy:compress(<<>>)),
+    ok.
+
+can_compress_and_decompress_empty_binary_test() ->
+    % Try to compress an empty binary...
+    {ok, Compressed} = snappy:compress(<<>>),
+    % Try to decompress the result of the compression...
+    {ok, Decompressed} = snappy:decompress(Compressed),
+    ok.
+
+can_compress_an_empty_binary_test() ->
+    % Try to compress an empty binary...
+    {ok, Compressed} = snappy:compress(<<>>),
+    % Check an empty binary was returned
+    ?assertMatch(Compressed,<<>>),
+    ok.
+
+can_decompress_an_empty_binary_test() ->
+    % Try to decompress an empty binary
+    {ok, Decompressed} = snappy:decompress(<<>>),
+    ?assertMatch(Decompressed,<<>>),
+    ok.