Replace many calls to sprintf with QUtil::hex_encode

Add QUtil::hex_encode to encode binary data has a hexadecimal string,
and use it in place of sprintf where possible.

ChangeLog

@@ -16,6 +16,9 @@
 
 2013-01-25  Jay Berkenbilt  <ejb@ql.org>
 
+	* New method QUtil::hex_encode to encode binary data as a
+	hexadecimal string
+
 	* qpdf --check was exiting with status 0 in some rare cases even
 	when errors were found.  It now always exits with one of the
 	document error codes (0 for success, 2 for errors, 3 or warnings).

examples/pdf-parse-content.cc

@@ -33,15 +33,7 @@ ParserCallbacks::handleObject(QPDFObjectHandle obj)
     std::cout << obj.getTypeName() << ": ";
     if (obj.isInlineImage())
     {
-        std::string val = obj.getInlineImageValue();
-        char buf[3];
-        buf[2] = '\0';
-        for (size_t i = 0; i < val.length(); ++i)
-        {
-            sprintf(buf, "%02x", (unsigned char)(val[i]));
-            std::cout << buf;
-        }
-        std::cout << std::endl;
+        std::cout << QUtil::hex_encode(obj.getInlineImageValue()) << std::endl;
     }
     else
     {

include/qpdf/QUtil.hh

@@ -56,6 +56,12 @@ namespace QUtil
     QPDF_DLL
     char* copy_string(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.
+    QPDF_DLL
+    std::string hex_encode(std::string const&);
+
     // Set stdin, stdout to binary mode
     QPDF_DLL
     void binary_stdout();

libqpdf/MD5.cc

@@ -386,16 +386,7 @@ void MD5::print()
 std::string MD5::unparse()
 {
     final();
-
-    char result[33];
-    char* p = result;
-    unsigned int i;
-    for (i = 0; i < 16; ++i)
-    {
-	sprintf(p, "%02x", digest_val[i]);
-	p += 2;
-    }
-    return result;
+    return QUtil::hex_encode(std::string((char*)digest_val, 16));
 }
 
 std::string

libqpdf/Pl_SHA2.cc

@@ -2,6 +2,7 @@
 #include <stdexcept>
 #include <cstdio>
 #include <qpdf/PointerHolder.hh>
+#include <qpdf/QUtil.hh>
 
 Pl_SHA2::Pl_SHA2(int bits, Pipeline* next) :
     Pipeline("sha2", next),
@@ -150,15 +151,5 @@ Pl_SHA2::getHexDigest()
 	throw std::logic_error(
 	    "digest requested for in-progress SHA2 Pipeline");
     }
-    std::string raw = getRawDigest();
-    size_t raw_size = raw.length();
-    size_t hex_size = 1 + (2 * raw_size);
-    PointerHolder<char> bufp(true, new char[hex_size]);
-    char* buf = bufp.getPointer();
-    buf[hex_size - 1] = '\0';
-    for (unsigned int i = 0; i < raw_size; ++i)
-    {
-        std::sprintf(buf + i * 2, "%02x", (unsigned char)raw[i]);
-    }
-    return buf;
+    return QUtil::hex_encode(getRawDigest());
 }

libqpdf/QPDF_Name.cc

@@ -2,6 +2,7 @@
 
 #include <string.h>
 #include <stdio.h>
+#include <qpdf/QUtil.hh>
 
 QPDF_Name::QPDF_Name(std::string const& name) :
     name(name)
@@ -16,7 +17,6 @@ std::string
 QPDF_Name::normalizeName(std::string const& name)
 {
     std::string result;
-    char num[4];
     result += name[0];
     for (unsigned int i = 1; i < name.length(); ++i)
     {
@@ -24,8 +24,7 @@ QPDF_Name::normalizeName(std::string const& name)
 	// Don't use locale/ctype here; follow PDF spec guidelines.
 	if (strchr("#()<>[]{}/%", ch) || (ch < 33) || (ch > 126))
 	{
-	    sprintf(num, "#%02x", (unsigned char) ch);
-	    result += num;
+            result += "#" + QUtil::hex_encode(std::string(&ch, 1));
 	}
 	else
 	{

libqpdf/QPDF_String.cc

@@ -90,14 +90,7 @@ QPDF_String::unparse(bool force_binary)
     std::string result;
     if (use_hexstring)
     {
-	result += "<";
-	char num[3];
-	for (unsigned int i = 0; i < this->val.length(); ++i)
-	{
-	    sprintf(num, "%02x", (unsigned char) this->val[i]);
-	    result += num;
-	}
-	result += ">";
+	result += "<" + QUtil::hex_encode(this->val) + ">";
     }
     else
     {

libqpdf/QUtil.cc

@@ -2,6 +2,7 @@
 #include <qpdf/qpdf-config.h>
 
 #include <qpdf/QUtil.hh>
+#include <qpdf/PointerHolder.hh>
 
 #include <stdio.h>
 #include <errno.h>
@@ -163,6 +164,21 @@ QUtil::copy_string(std::string const& str)
     return result;
 }
 
+std::string
+QUtil::hex_encode(std::string const& input)
+{
+    size_t input_size = input.length();
+    size_t hex_size = 1 + (2 * input_size);
+    PointerHolder<char> bufp(true, new char[hex_size]);
+    char* buf = bufp.getPointer();
+    buf[hex_size - 1] = '\0';
+    for (unsigned int i = 0; i < input_size; ++i)
+    {
+        sprintf(buf + i * 2, "%02x", (unsigned char)input[i]);
+    }
+    return buf;
+}
+
 void
 QUtil::binary_stdout()
 {

qpdf/test_driver.cc

@@ -75,16 +75,9 @@ ParserCallbacks::handleObject(QPDFObjectHandle obj)
     std::cout << obj.getTypeName() << ": ";
     if (obj.isInlineImage())
     {
+        // Exercise getTypeCode
         assert(obj.getTypeCode() == QPDFObject::ot_inlineimage);
-        std::string val = obj.getInlineImageValue();
-        char buf[3];
-        buf[2] = '\0';
-        for (size_t i = 0; i < val.length(); ++i)
-        {
-            sprintf(buf, "%02x", (unsigned char)(val[i]));
-            std::cout << buf;
-        }
-        std::cout << std::endl;
+        std::cout << QUtil::hex_encode(obj.getInlineImageValue()) << std::endl;
     }
     else
     {