add is_executable_binary()

Author: scivision

+stdlib/is_executable_binary.m

@@ -0,0 +1,44 @@
+function y = is_executable_binary(filename)
+% IS_EXECUTABLE_BINARY Check if a file is an executable binary by examining magic numbers
+%
+% NOTE: on Unix-like operating systems, often times what users run thinking
+% it's a "program" is actually a shell script invoking a binary with
+% options.
+%    fullfile(matlabroot, 'bin/matlab')
+% is a shell script and thus is FALSE for this function.
+
+y = false;
+
+fid = fopen(filename, 'rb');
+if fid < 0, return, end
+
+N = 4;
+if ispc(), N = 2; end
+
+magic = fread(fid, N, 'uint8').';
+fclose(fid);
+if numel(magic) < N, return, end
+
+if ispc()
+    y = isequal(magic(1:2), [0x4d, 0x5a]);
+    % Check for PE magic number (MZ)
+elseif ismac()
+    % Check for Mach-O magic number
+    feedface = [0xFE, 0xED, 0xFA, 0xCE];
+    feedfacf = [0xFE, 0xED, 0xFA, 0xCF];
+    cafebabe = [0xCA, 0xFE, 0xBA, 0xBE];
+    cafebabf = [0xCA, 0xFE, 0xBA, 0xBF];
+    for a = {feedface, fliplr(feedface), ...
+             feedfacf, fliplr(feedfacf), ...
+             cafebabe, fliplr(cafebabe), ...
+             cafebabf, fliplr(cafebabf)}
+
+       y = isequal(magic, a{1});
+       if y, return, end
+    end
+else
+    % Check for ELF magic number (0x7f followed by 'ELF')
+    y = isequal(magic, [0x7f, 0x45, 0x4c, 0x46]);
+end
+
+end

test/TestFileImpure.m

@@ -24,9 +24,9 @@ function test_file_size(tc, p_file_size)
 
 
 function test_null_file(tc)
-import matlab.unittest.constraints.IsFile
 tc.assumeFalse(ispc)
-tc.verifyThat(stdlib.null_file, IsFile)
+
+tc.verifyThat(stdlib.null_file, matlab.unittest.constraints.IsFile)
 end
 
 

test/TestIsExe.m

@@ -31,13 +31,35 @@ function test_is_exe_dir(tc, fun)
 function test_matlab_exe(tc, fun)
 is_capable(tc, fun)
 
-f = fullfile(matlabroot, "bin/matlab");
+
+f = matlab_path();
+tc.verifyTrue(fun(f))
+end
+
+
+function test_is_executable_binary(tc)
+
 if ispc()
-  f = f + ".exe";
+  f = matlab_path();
+else
+  f = '/bin/ls';
 end
 
-tc.verifyTrue(fun(f))
+tc.assumeThat(f, matlab.unittest.constraints.IsFile)
+
+b = stdlib.is_executable_binary(f);
+tc.assumeTrue(b, f)
+
+end
 end
 
 end
+
+
+function f = matlab_path()
+
+f = fullfile(matlabroot, "bin/matlab");
+if ispc()
+  f = f + ".exe";
 end
+end