Improve use of std::unique_ptr

* Use unique_ptr in place of shared_ptr in some cases
* unique_ptr for arrays does not require a custom deleter
* use std::make_unique (c++14) where possible

ChangeLog

@@ -1,3 +1,9 @@
+2022-02-05  Jay Berkenbilt  <ejb@ql.org>
+
+	* Add QUtil::make_unique_cstr to return a std::unique_ptr<char[]>
+	as an alternative to QUtil::copy_string and
+	QUtil::make_shared_cstr.
+
 2022-02-04  Jay Berkenbilt  <ejb@ql.org>
 
 	* New preprocessor symbols QPDF_MAJOR_VERSION, QPDF_MINOR_VERSION,

TODO

@@ -1,6 +1,9 @@
 10.6
 ====
 
+* Expose emptyPDF to the C API. Ensure that qpdf_get_qpdf_version is
+  always static.
+
 * Consider doing one big commit to reformat the entire codebase using
   clang-format or a similar tool. Consider using blame.ignoreRevsFile
   or similar (or otherwise study git blame to see how to minimize the
@@ -364,6 +367,13 @@ auto x_ph = std::make_shared<X>(); X* x = x_ph.get();
 Derived* x = new Derived(); PointerHolder<Base> x_ph(x) -->
 Derived* x = new Derived(); auto x_ph = std::shared_pointer<Base>(x);
 
+Also remember
+
+auto x = std::shared_ptr(new T[5], std::default_delete<T[]>())
+vs.
+auto x = std::make_unique<T[]>(5)
+
+
 PointerHolder in public API:
 
   QUtil::read_file_into_memory(

include/qpdf/QUtil.hh

@@ -161,6 +161,10 @@ namespace QUtil
     QPDF_DLL
     std::shared_ptr<char> make_shared_cstr(std::string const&);
 
+    // Copy string as a unique_ptr to an array.
+    QPDF_DLL
+    std::unique_ptr<char[]> make_unique_cstr(std::string const&);
+
     // Returns lower-case hex-encoded version of the string, treating
     // each character in the input string as unsigned.  The output
     // string will be twice as long as the input string.

libqpdf/AES_PDF_native.cc

@@ -19,12 +19,8 @@ AES_PDF_native::AES_PDF_native(bool encrypt, unsigned char const* key,
     nrounds(0)
 {
     size_t keybits = 8 * key_bytes;
-    this->key = std::unique_ptr<unsigned char[]>(
+    this->key = std::make_unique<unsigned char[]>(key_bytes);
-        new unsigned char[key_bytes],
+    this->rk = std::make_unique<uint32_t[]>(RKLENGTH(keybits));
-        std::default_delete<unsigned char[]>());
-    this->rk = std::unique_ptr<uint32_t[]>(
-        new uint32_t[RKLENGTH(keybits)],
-        std::default_delete<uint32_t[]>());
     size_t rk_bytes = RKLENGTH(keybits) * sizeof(uint32_t);
     std::memcpy(this->key.get(), key, key_bytes);
     std::memset(this->rk.get(), 0, rk_bytes);

libqpdf/Pl_AES_PDF.cc

@@ -25,9 +25,7 @@ Pl_AES_PDF::Pl_AES_PDF(char const* identifier, Pipeline* next,
     use_specified_iv(false),
     disable_padding(false)
 {
-    this->key = std::unique_ptr<unsigned char[]>(
+    this->key = std::make_unique<unsigned char[]>(key_bytes);
-        new unsigned char[key_bytes],
-        std::default_delete<unsigned char[]>());
     std::memcpy(this->key.get(), key, key_bytes);
     std::memset(this->inbuf, 0, this->buf_size);
     std::memset(this->outbuf, 0, this->buf_size);

libqpdf/QPDFArgParser.cc

@@ -20,7 +20,7 @@ QPDFArgParser::Members::Members(
     option_table(nullptr),
     final_check_handler(nullptr)
 {
-    auto tmp = QUtil::make_shared_cstr(argv[0]);
+    auto tmp = QUtil::make_unique_cstr(argv[0]);
     char* p = QUtil::getWhoami(tmp.get());
     // Remove prefix added by libtool for consistency during testing.
     if (strncmp(p, "lt-", 3) == 0)

libqpdf/QPDFJob.cc

@@ -3379,7 +3379,7 @@ QPDFJob::setEncryptionOptions(QPDF& pdf, QPDFWriter& w)
 static void parse_version(std::string const& full_version_string,
                           std::string& version, int& extension_level)
 {
-    auto vp = QUtil::make_shared_cstr(full_version_string);
+    auto vp = QUtil::make_unique_cstr(full_version_string);
     char* v = vp.get();
     char* p1 = strchr(v, '.');
     char* p2 = (p1 ? strchr(1 + p1, '.') : 0);

libqpdf/QPDFWriter.cc

@@ -1919,7 +1919,7 @@ QPDFWriter::unparseObject(QPDFObjectHandle object, int level,
 	    }
 	    else
 	    {
-		auto tmp_ph = QUtil::make_shared_cstr(val);
+		auto tmp_ph = QUtil::make_unique_cstr(val);
                 char* tmp = tmp_ph.get();
 		size_t vlen = val.length();
 		RC4 rc4(QUtil::unsigned_char_pointer(this->m->cur_data_key),

libqpdf/QPDF_encryption.cc

@@ -1211,7 +1211,7 @@ QPDF::decryptString(std::string& str, int objid, int generation)
 	    size_t vlen = str.length();
 	    // Using PointerHolder guarantees that tmp will
 	    // be freed even if rc4.process throws an exception.
-	    auto tmp = QUtil::make_shared_cstr(str);
+	    auto tmp = QUtil::make_unique_cstr(str);
 	    RC4 rc4(QUtil::unsigned_char_pointer(key), toI(key.length()));
 	    rc4.process(QUtil::unsigned_char_pointer(tmp.get()), vlen);
 	    str = std::string(tmp.get(), vlen);

libqpdf/QUtil.cc

@@ -744,6 +744,16 @@ QUtil::make_shared_cstr(std::string const& str)
     return result;
 }
 
+std::unique_ptr<char[]>
+QUtil::make_unique_cstr(std::string const& str)
+{
+    auto result = std::make_unique<char[]>(str.length() + 1);
+    // Use memcpy in case string contains nulls
+    result.get()[str.length()] = '\0';
+    memcpy(result.get(), str.c_str(), str.length());
+    return result;
+}
+
 std::string
 QUtil::hex_encode(std::string const& input)
 {
@@ -2625,7 +2635,7 @@ call_main_from_wmain(bool, int argc, wchar_t const* const argv[],
     // other systems. That way the rest of qpdf.cc can just act like
     // arguments are UTF-8.
 
-    std::vector<std::shared_ptr<char>> utf8_argv;
+    std::vector<std::unique_ptr<char[]>> utf8_argv;
     for (int i = 0; i < argc; ++i)
     {
         std::string utf16;
@@ -2638,11 +2648,9 @@ call_main_from_wmain(bool, int argc, wchar_t const* const argv[],
                              QIntC::to_uchar(codepoint & 0xff)));
         }
         std::string utf8 = QUtil::utf16_to_utf8(utf16);
-        utf8_argv.push_back(QUtil::make_shared_cstr(utf8));
+        utf8_argv.push_back(QUtil::make_unique_cstr(utf8));
     }
-    auto utf8_argv_sp =
+    auto utf8_argv_sp = std::make_unique<char*[]>(1+utf8_argv.size());
-        std::shared_ptr<char*>(
-            new char*[1+utf8_argv.size()], std::default_delete<char*[]>());
     char** new_argv = utf8_argv_sp.get();
     for (size_t i = 0; i < utf8_argv.size(); ++i)
     {

libqpdf/qpdfjob-c.cc

@@ -9,7 +9,7 @@
 
 int qpdfjob_run_from_argv(char const* const argv[])
 {
-    auto whoami_p = QUtil::make_shared_cstr(argv[0]);
+    auto whoami_p = QUtil::make_unique_cstr(argv[0]);
     auto whoami = QUtil::getWhoami(whoami_p.get());
     QUtil::setLineBuf(stdout);
 

libtests/qtest/qutil/qutil.out

@@ -23,6 +23,7 @@ one
 7
 compare okay
 compare okay
+compare okay
 -2147483648 to int: PASSED
 2147483647 to int: PASSED
 2147483648 to int threw (integer out of range converting 2147483648 from a 8-byte signed type to a 4-byte signed type): PASSED

libtests/qutil.cc

@@ -150,7 +150,7 @@ void string_conversion_test()
 	std::cout << "compare failed" << std::endl;
     }
     delete [] tmp;
-    // Also test with make_shared_cstr
+    // Also test with make_shared_cstr and make_unique_cstr
     auto tmp2 = QUtil::make_shared_cstr(embedded_null);
     if (memcmp(tmp2.get(), embedded_null.c_str(), 7) == 0)
     {
@@ -160,6 +160,15 @@ void string_conversion_test()
     {
 	std::cout << "compare failed" << std::endl;
     }
+    auto tmp3 = QUtil::make_unique_cstr(embedded_null);
+    if (memcmp(tmp3.get(), embedded_null.c_str(), 7) == 0)
+    {
+	std::cout << "compare okay" << std::endl;
+    }
+    else
+    {
+	std::cout << "compare failed" << std::endl;
+    }
 
     std::string int_max_str = QUtil::int_to_string(INT_MAX);
     std::string int_min_str = QUtil::int_to_string(INT_MIN);
@@ -417,7 +426,7 @@ void transcoding_test()
 
 void print_whoami(char const* str)
 {
-    auto dup = QUtil::make_shared_cstr(str);
+    auto dup = QUtil::make_unique_cstr(str);
     std::cout << QUtil::getWhoami(dup.get()) << std::endl;
 }
 

libtests/rc4.cc

@@ -14,8 +14,7 @@ static void other_tests()
     // Test cases not covered by the pipeline: string as key, convert
     // in place
     RC4 r(reinterpret_cast<unsigned char const*>("quack"));
-    auto data = std::unique_ptr<unsigned char[]>(
+    auto data = std::make_unique<unsigned char[]>(6);
-        new unsigned char[6], std::default_delete<unsigned char[]>());
     memcpy(data.get(), "potato", 6);
     r.process(data.get(), 6);
     assert(memcmp(data.get(), "\xa5\x6f\xe7\x27\x2b\x5c", 6) == 0);