Security: replace operator[] with at

For std::string and std::vector, replace operator[] with at. This was done using an automated process. See README.hardening for details.

Security: replace operator[] with at
For std::string and std::vector, replace operator[] with at. This was done using an automated process. See README.hardening for details.
Jay Berkenbilt
1 parent 42294570
Showing 23 changed files with 254 additions and 153 deletions
ChangeLog
README.hardening
README.maintainer
examples/pdf-bookmarks.cc
examples/pdf-mod-info.cc
examples/pdf-parse-content.cc
libqpdf/Pl_LZWDecoder.cc
libqpdf/QPDF.cc
libqpdf/QPDFObjectHandle.cc
libqpdf/QPDFTokenizer.cc
libqpdf/QPDFWriter.cc
libqpdf/QPDF_Array.cc
libqpdf/QPDF_Name.cc
libqpdf/QPDF_Stream.cc
libqpdf/QPDF_String.cc
libqpdf/QPDF_encryption.cc
libqpdf/QPDF_linearization.cc
libqpdf/QPDF_optimization.cc
libqpdf/QPDF_pages.cc
libqpdf/QUtil.cc
 2013-10-05  Jay Berkenbilt  <ejb@ql.org>
+	* Replace operator[] in std::string and std::vector with "at" in
+	order to get bounds checking.  This reduces the chances that
+	incorrect code will result in data exposure or buffer overruns.
+	See README.hardening for additional notes.
+
 	* Use cryptographically secure random number generation when
 	available.  See additional notes in README.
+Avoiding operator[]
+===================
+
+During a security review by Red Hat security team (specifically
+Florian Weimer), it was discovered that qpdf used std::string and
+std::vector's operator[], which has no bounds checking by design.
+Instead, using those objects' at() method is preferable since it does
+bounds checking.  Florian has a tool that can detect all uses of these
+methods and report them.  I have a short perl script that
+automatically corrects any such uses.  The perl script is not intended
+to be general, but it could be reasonably general.  The only known
+shortcut is that it might not work very well with some cases of nested
+[]'s like a[b[c]] or with cases where there are line breaks inside the
+brackets.  For qpdf's coding style, it worked on all cases reported.
+
+To use this, obtain htcondor-analyzer, run it, and respond to the
+report.  Here's what I did.
+
+sudo aptitude install libclang-dev llvm llvm-dev clang
+cd /tmp
+git clone https://github.com/fweimer/htcondor-analyzer
+# HEAD = 5fa06fc68a9b0677e9de162279185d58ba1e8477 at this writing
+cd htcondor-analyzer
+make
+
+in qpdf
+
+./autogen.sh
+/tmp/htcondor-analyzer/create-db
+CC=/tmp/htcondor-analyzer/cc CXX=/tmp/htcondor-analyzer/cxx ./configure --disable-shared --disable-werror
+# to remove conftest.c
+\rm htcondor-analyzer.sqlite
+/tmp/htcondor-analyzer/create-db
+
+Repeat until no more errors:
+
+/tmp/fix-at.pl is shown below.
+
+make
+/tmp/htcondor-analyzer/report | grep std:: | grep qpdf >| /tmp/r
+perl /tmp/fix-at.pl /tmp/r
+# move all *.new over the original file.  patmv is my script.  Can
+# also use a for loop.
+patmv -f s/.new// **/*.new
+
+---------- /tmp/fix-at.pl ----------
+#!/usr/bin/env perl
+require 5.008;
+use warnings;
+use strict;
+use File::Basename;
+
+my $whoami = basename($0);
+
+my %to_fix = ();
+while (<>)
+{
+    chomp;
+    die unless m/^([^:]+):(\d+):(\d+):\s*(.*)$/;
+    my ($file, $line, $col, $message) = ($1, $2, $3, $4);
+    if ($message !~ m/operator\[\]/)
+    {
+        warn "skipping $_\n";
+        next;
+    }
+    push(@{$to_fix{$file}}, [$line, $col, $message]);
+}
+foreach my $file (sort keys %to_fix)
+{
+    open(F, "<$file") or die;
+    my @lines = (<F>);
+    close(F);
+    my $last = "";
+    my @data = reverse sort { ($a->[0] <=> $b->[0]) || ($a->[1] <=> $b->[1]) } @{$to_fix{$file}};
+    foreach my $d (@data)
+    {
+        my ($line, $col) = @$d;
+        next if $last eq "$line:$col";
+        $last = "$line:$col";
+        die if $line-- < 1;
+        die if $col-- < 1;
+        print $lines[$line];
+        $lines[$line] =~ s/^(.{$col})([^\[]+)\[([^\]]+)\]/$1$2.at($3)/ or die "$file:$last\n";
+        print $lines[$line];
+    }
+    open(F, ">$file.new") or die;
+    foreach my $line (@lines)
+    {
+        print F $line;
+    }
+    close(F) or die;
+}
+--------------------
@@ -43,6 +43,9 @@ Release Reminders
    casting policy in the manual, and ensure that integer types are
    properly handled.
+ * Remember to avoid using operator[] with std::string or
+   std::vector.  See README.hardening for details.
+
  * Increment shared library version information as needed
    (libqpdf/build.mk)
@@ -31,7 +31,7 @@ void print_lines(std::vector&lt;int&gt;&amp; numbers)
 {
     for (unsigned int i = 0; i < numbers.size() - 1; ++i)
     {
-	if (numbers[i])
+	if (numbers.at(i))
 	{
 	    std::cout << "| ";
 	}
@@ -128,7 +128,7 @@ int main(int argc, char* argv[])
 	{
 	    QTC::TC("examples", "pdf-mod-info -key");
 	    cur_key = argv[i];
-	    if (! ((cur_key.length() > 0) && (cur_key[0] == '/')))
+	    if (! ((cur_key.length() > 0) && (cur_key.at(0) == '/')))
 	    {
 		cur_key = "/" + cur_key;
 	    }
@@ -74,7 +74,7 @@ int main(int argc, char* argv[])
             usage();
         }
-        QPDFObjectHandle page = pages[pageno-1];
+        QPDFObjectHandle page = pages.at(pageno-1);
         QPDFObjectHandle contents = page.getKey("/Contents");
         ParserCallbacks cb;
         QPDFObjectHandle::parseContentStream(contents, &cb);
@@ -109,7 +109,7 @@ Pl_LZWDecoder::getFirstChar(int code)
             throw std::logic_error(
                 "Pl_LZWDecoder::getFirstChar: table overflow");
         }
-	Buffer& b = table[idx];
+	Buffer& b = table.at(idx);
 	result = b.getBuffer()[0];
     }
     else
@@ -142,7 +142,7 @@ Pl_LZWDecoder::addToTable(unsigned char next)
             throw std::logic_error(
                 "Pl_LZWDecoder::addToTable: table overflow");
         }
-	Buffer& b = table[idx];
+	Buffer& b = table.at(idx);
 	last_data = b.getBuffer();
 	last_size = b.getSize();
     }
@@ -238,7 +238,7 @@ Pl_LZWDecoder::handleCode(int code)
 	}
 	else
 	{
-	    Buffer& b = table[code - 258];
+	    Buffer& b = table.at(code - 258);
 	    getNext()->write(b.getBuffer(), b.getSize());
 	}
     }
@@ -531,7 +531,7 @@ QPDF::read_xrefTable(qpdf_offset_t xref_offset)
             // For xref_table, these will always be small enough to be ints 
 	    qpdf_offset_t f1 = QUtil::string_to_ll(m2.getMatch(1).c_str());
 	    int f2 = atoi(m2.getMatch(2).c_str());
-	    char type = m2.getMatch(3)[0];
+	    char type = m2.getMatch(3).at(0);
 	    if (type == 'f')
 	    {
 		// Save deleted items until after we've checked the
@@ -758,17 +758,17 @@ QPDF::processXRefStream(qpdf_offset_t xref_offset, QPDFObjectHandle&amp; xref_obj)
     long long num_entries = 0;
     for (unsigned int i = 1; i < indx.size(); i += 2)
     {
-        if (indx[i] > max_num_entries - num_entries)
+        if (indx.at(i) > max_num_entries - num_entries)
         {
             throw QPDFExc(qpdf_e_damaged_pdf, this->file->getName(),
                           "xref stream", xref_offset,
                           "Cross-reference stream claims to contain"
                           " too many entries: " +
-                          QUtil::int_to_string(indx[i]) + " " +
+                          QUtil::int_to_string(indx.at(i)) + " " +
                           QUtil::int_to_string(max_num_entries) + " " +
                           QUtil::int_to_string(num_entries));
         }
-	num_entries += indx[i];
+	num_entries += indx.at(i);
     }
     // entry_size and num_entries have both been validated to ensure
@@ -829,9 +829,9 @@ QPDF::processXRefStream(qpdf_offset_t xref_offset, QPDFObjectHandle&amp; xref_obj)
 	// based on /Index.  The generation number is 0 unless this is
 	// an uncompressed object record, in which case the generation
 	// number appears as the third field.
-	int obj = indx[cur_chunk] + chunk_count;
+	int obj = indx.at(cur_chunk) + chunk_count;
 	++chunk_count;
-	if (chunk_count >= indx[cur_chunk + 1])
+	if (chunk_count >= indx.at(cur_chunk + 1))
 	{
 	    cur_chunk += 2;
 	    chunk_count = 0;
@@ -712,7 +712,7 @@ QPDFObjectHandle::parse(std::string const&amp; object_str,
     size_t offset = input->tell();
     while (offset < object_str.length())
     {
-        if (! isspace(object_str[offset]))
+        if (! isspace(object_str.at(offset)))
         {
             QTC::TC("qpdf", "QPDFObjectHandle trailing data in parse");
             throw QPDFExc(qpdf_e_damaged_pdf, input->getName(),
@@ -966,8 +966,8 @@ QPDFObjectHandle::parseInternal(PointerHolder&lt;InputSource&gt; input,
 		std::string const& value = token.getValue();
 		if ((value == "R") && (in_array || in_dictionary) &&
 		    (olist.size() >= 2) &&
-		    (olist[olist.size() - 1].isInteger()) &&
-		    (olist[olist.size() - 2].isInteger()))
+		    (olist.at(olist.size() - 1).isInteger()) &&
+		    (olist.at(olist.size() - 2).isInteger()))
 		{
                     if (context == 0)
                     {
@@ -979,8 +979,8 @@ QPDFObjectHandle::parseInternal(PointerHolder&lt;InputSource&gt; input,
 		    // Try to resolve indirect objects
 		    object = newIndirect(
 			context,
-			olist[olist.size() - 2].getIntValue(),
-			olist[olist.size() - 1].getIntValue());
+			olist.at(olist.size() - 2).getIntValue(),
+			olist.at(olist.size() - 1).getIntValue());
 		    olist.pop_back();
 		    olist.pop_back();
 		}
@@ -1067,8 +1067,8 @@ QPDFObjectHandle::parseInternal(PointerHolder&lt;InputSource&gt; input,
 	}
 	for (unsigned int i = 0; i < olist.size(); i += 2)
 	{
-	    QPDFObjectHandle key_obj = olist[i];
-	    QPDFObjectHandle val = olist[i + 1];
+	    QPDFObjectHandle key_obj = olist.at(i);
+	    QPDFObjectHandle val = olist.at(i + 1);
 	    if (! key_obj.isName())
 	    {
 		throw QPDFExc(
@@ -61,7 +61,7 @@ QPDFTokenizer::resolveLiteral()
 {
     PCRE num_re("^[\\+\\-]?(?:\\.\\d+|\\d+(?:\\.\\d+)?)$");
-    if ((val.length() > 0) && (val[0] == '/'))
+    if ((val.length() > 0) && (val.at(0) == '/'))
     {
         type = tt_name;
         // Deal with # in name token.  Note: '/' by itself is a
@@ -397,8 +397,8 @@ QPDFTokenizer::presentCharacter(char ch)
 	    std::string nval;
 	    for (unsigned int i = 0; i < val.length(); i += 2)
 	    {
-		num[0] = val[i];
-		num[1] = val[i+1];
+		num[0] = val.at(i);
+		num[1] = val.at(i+1);
 		char nch = static_cast<char>(strtol(num, 0, 16));
 		nval += nch;
 	    }
@@ -1569,7 +1569,7 @@ QPDFWriter::writeObjectStreamOffsets(std::vector&lt;qpdf_offset_t&gt;&amp; offsets,
 	}
 	writeString(QUtil::int_to_string(i + first_obj));
 	writeString(" ");
-	writeString(QUtil::int_to_string(offsets[i]));
+	writeString(QUtil::int_to_string(offsets.at(i)));
     }
     writeString("\n");
 }
@@ -1603,7 +1603,7 @@ QPDFWriter::writeObjectStream(QPDFObjectHandle object)
 	{
 	    // Adjust offsets to skip over comment before first object
-	    first = offsets[0];
+	    first = offsets.at(0);
 	    for (std::vector<qpdf_offset_t>::iterator iter = offsets.begin();
 		 iter != offsets.end(); ++iter)
 	    {
@@ -2745,7 +2745,7 @@ QPDFWriter::writeLinearized()
 	if (pass == 2)
 	{
 	    std::vector<QPDFObjectHandle> const& pages = pdf.getAllPages();
-	    int first_page_object = obj_renumber[pages[0].getObjGen()];
+	    int first_page_object = obj_renumber[pages.at(0).getObjGen()];
 	    int npages = pages.size();
 	    writeString(" /Linearized 1 /L ");
@@ -60,7 +60,7 @@ QPDF_Array::getItem(int n) const
 	throw std::logic_error(
 	    "INTERNAL ERROR: bounds error accessing QPDF_Array element");
     }
-    return this->items[n];
+    return this->items.at(n);
 }
 std::vector<QPDFObjectHandle> const&
@@ -74,7 +74,7 @@ QPDF_Array::setItem(int n, QPDFObjectHandle const&amp; oh)
 {
     // Call getItem for bounds checking
     (void) getItem(n);
-    this->items[n] = oh;
+    this->items.at(n) = oh;
 }
 void
@@ -21,10 +21,10 @@ QPDF_Name::normalizeName(std::string const&amp; name)
 	return name;
     }
     std::string result;
-    result += name[0];
+    result += name.at(0);
     for (unsigned int i = 1; i < name.length(); ++i)
     {
-	char ch = name[i];
+	char ch = name.at(i);
 	// Don't use locale/ctype here; follow PDF spec guidelines.
 	if (strchr("#()<>[]{}/%", ch) || (ch < 33) || (ch > 126))
 	{
@@ -310,7 +310,7 @@ QPDF_Stream::filterable(std::vector&lt;std::string&gt;&amp; filters,
     for (unsigned int i = 0; i < filters.size(); ++i)
     {
-        QPDFObjectHandle decode_item = decode_parms[i];
+        QPDFObjectHandle decode_item = decode_parms.at(i);
         if (decode_item.isNull())
         {
             // okay
@@ -318,7 +318,7 @@ QPDF_Stream::filterable(std::vector&lt;std::string&gt;&amp; filters,
         else if (decode_item.isDictionary())
         {
             if (! understandDecodeParams(
-                    filters[i], decode_item,
+                    filters.at(i), decode_item,
                     predictor, columns, early_code_change))
             {
                 filterable = false;
@@ -55,7 +55,7 @@ QPDF_String::unparse(bool force_binary)
 	int consecutive_printable = 0;
 	for (unsigned int i = 0; i < this->val.length(); ++i)
 	{
-	    char ch = this->val[i];
+	    char ch = this->val.at(i);
 	    // Note: do not use locale to determine printability.  The
 	    // PDF specification accepts arbitrary binary data.  Some
 	    // locales imply multibyte characters.  We'll consider
@@ -97,7 +97,7 @@ QPDF_String::unparse(bool force_binary)
 	result += "(";
 	for (unsigned int i = 0; i < this->val.length(); ++i)
 	{
-	    char ch = this->val[i];
+	    char ch = this->val.at(i);
 	    switch (ch)
 	    {
 	      case '\n':
@@ -135,7 +135,7 @@ QPDF_String::unparse(bool force_binary)
 	      default:
 		if (is_iso_latin1_printable(ch))
 		{
-		    result += this->val[i];
+		    result += this->val.at(i);
 		}
 		else
 		{
@@ -164,7 +164,7 @@ QPDF_String::getUTF8Val() const
     std::string result;
     size_t len = this->val.length();
     if ((len >= 2) && (len % 2 == 0) &&
-	(this->val[0] == '\xfe') && (this->val[1] == '\xff'))
+	(this->val.at(0) == '\xfe') && (this->val.at(1) == '\xff'))
     {
 	// This is a Unicode string using big-endian UTF-16.  This
 	// code uses unsigned long and unsigned short to hold
@@ -181,8 +181,8 @@ QPDF_String::getUTF8Val() const
 	    // discarded, and a low codepoint not preceded by a high
 	    // codepoint will just get its low 10 bits output.
 	    unsigned short bits =
-		(static_cast<unsigned char>(this->val[i]) << 8) +
-		static_cast<unsigned char>(this->val[i+1]);
+		(static_cast<unsigned char>(this->val.at(i)) << 8) +
+		static_cast<unsigned char>(this->val.at(i+1));
 	    if ((bits & 0xFC00) == 0xD800)
 	    {
 		codepoint = 0x10000 + ((bits & 0x3FF) << 10);
@@ -209,7 +209,7 @@ QPDF_String::getUTF8Val() const
     {
 	for (unsigned int i = 0; i < len; ++i)
 	{
-	    result += QUtil::toUTF8(static_cast<unsigned char>(this->val[i]));
+	    result += QUtil::toUTF8(static_cast<unsigned char>(this->val.at(i)));
 	}
     }
     return result;
@@ -312,7 +312,7 @@ hash_V5(std::string const&amp; password,
             int E_mod_3 = 0;
             for (unsigned int i = 0; i < 16; ++i)
             {
-                E_mod_3 += static_cast<unsigned char>(E[i]);
+                E_mod_3 += static_cast<unsigned char>(E.at(i));
             }
             E_mod_3 %= 3;
             int next_hash = ((E_mod_3 == 0) ? 256 :
@@ -33,7 +33,7 @@ load_vector_int(BitStream&amp; bit_stream, int nitems, std::vector&lt;T&gt;&amp; vec,
         {
             vec.push_back(T());
         }
-	vec[i].*field = bit_stream.getBits(bits_wanted);
+	vec.at(i).*field = bit_stream.getBits(bits_wanted);
     }
     if (static_cast<int>(vec.size()) != nitems)
     {
@@ -54,9 +54,9 @@ load_vector_vector(BitStream&amp; bit_stream,
     // into the vec2 vector field of the ith item of vec1.
     for (int i1 = 0; i1 < nitems1; ++i1)
     {
-	for (int i2 = 0; i2 < vec1[i1].*nitems2; ++i2)
+	for (int i2 = 0; i2 < vec1.at(i1).*nitems2; ++i2)
 	{
-	    (vec1[i1].*vec2).push_back(bit_stream.getBits(bits_wanted));
+	    (vec1.at(i1).*vec2).push_back(bit_stream.getBits(bits_wanted));
 	}
     }
     bit_stream.skipToNextByte();
@@ -237,8 +237,8 @@ QPDF::readLinearizationData()
     }
     // H: hint table offset/length for primary and overflow hint tables
-    int H0_offset = H_items[0];
-    int H0_length = H_items[1];
+    int H0_offset = H_items.at(0);
+    int H0_length = H_items.at(1);
     int H1_offset = 0;
     int H1_length = 0;
     if (H_items.size() == 4)
@@ -246,8 +246,8 @@ QPDF::readLinearizationData()
 	// Acrobat doesn't read or write these (as PDF 1.4), so we
 	// don't have a way to generate a test case.
 	// QTC::TC("qpdf", "QPDF overflow hint table");
-	H1_offset = H_items[2];
-	H1_length = H_items[3];
+	H1_offset = H_items.at(2);
+	H1_length = H_items.at(3);
     }
     // P: first page number
@@ -470,7 +470,7 @@ QPDF::readHSharedObject(BitStream h)
 		    1, &HSharedObjectEntry::signature_present);
     for (int i = 0; i < nitems; ++i)
     {
-	if (entries[i].signature_present)
+	if (entries.at(i).signature_present)
 	{
 	    // Skip 128-bit MD5 hash.  These are not supported by
 	    // acrobat, so they should probably never be there.  We
@@ -512,7 +512,7 @@ QPDF::checkLinearizationInternal()
     // O: object number of first page
     std::vector<QPDFObjectHandle> const& pages = getAllPages();
-    if (p.first_page_object != pages[0].getObjectID())
+    if (p.first_page_object != pages.at(0).getObjectID())
     {
 	QTC::TC("qpdf", "QPDF err /O mismatch");
 	errors.push_back("first page object (/O) mismatch");
@@ -528,7 +528,7 @@ QPDF::checkLinearizationInternal()
     for (int i = 0; i < npages; ++i)
     {
-	QPDFObjectHandle const& page = pages[i];
+	QPDFObjectHandle const& page = pages.at(i);
 	QPDFObjGen og(page.getObjGen());
 	if (this->xref_table[og].getType() == 2)
 	{
@@ -776,7 +776,7 @@ QPDF::checkHPageOffset(std::list&lt;std::string&gt;&amp; errors,
     unsigned int npages = pages.size();
     int table_offset = adjusted_offset(
 	this->page_offset_hints.first_page_offset);
-    QPDFObjGen first_page_og(pages[0].getObjGen());
+    QPDFObjGen first_page_og(pages.at(0).getObjGen());
     assert(this->xref_table.count(first_page_og) > 0);
     int offset = getLinearizationOffset(first_page_og);
     if (table_offset != offset)
@@ -786,13 +786,13 @@ QPDF::checkHPageOffset(std::list&lt;std::string&gt;&amp; errors,
     for (unsigned int pageno = 0; pageno < npages; ++pageno)
     {
-	QPDFObjGen page_og(pages[pageno].getObjGen());
+	QPDFObjGen page_og(pages.at(pageno).getObjGen());
 	int first_object = page_og.getObj();
 	assert(this->xref_table.count(page_og) > 0);
 	offset = getLinearizationOffset(page_og);
-	HPageOffsetEntry& he = this->page_offset_hints.entries[pageno];
-	CHPageOffsetEntry& ce = this->c_page_offset_data.entries[pageno];
+	HPageOffsetEntry& he = this->page_offset_hints.entries.at(pageno);
+	CHPageOffsetEntry& ce = this->c_page_offset_data.entries.at(pageno);
 	int h_nobjects = he.delta_nobjects +
 	    this->page_offset_hints.min_nobjects;
 	if (h_nobjects != ce.nobjects)
@@ -837,7 +837,7 @@ QPDF::checkHPageOffset(std::list&lt;std::string&gt;&amp; errors,
 	for (int i = 0; i < he.nshared_objects; ++i)
 	{
-	    int idx = he.shared_identifiers[i];
+	    int idx = he.shared_identifiers.at(i);
 	    if (shared_idx_to_obj.count(idx) == 0)
             {
                 throw std::logic_error(
@@ -849,13 +849,13 @@ QPDF::checkHPageOffset(std::list&lt;std::string&gt;&amp; errors,
 	for (int i = 0; i < ce.nshared_objects; ++i)
 	{
-	    int idx = ce.shared_identifiers[i];
+	    int idx = ce.shared_identifiers.at(i);
 	    if (idx >= this->c_shared_object_data.nshared_total)
             {
                 throw std::logic_error(
                     "index out of bounds for shared object hint table");
             }
-	    int obj = this->c_shared_object_data.entries[idx].object;
+	    int obj = this->c_shared_object_data.entries.at(idx).object;
 	    computed_shared.insert(obj);
 	}
@@ -923,7 +923,7 @@ QPDF::checkHSharedObject(std::list&lt;std::string&gt;&amp; errors,
 	// The first nshared_first_page objects are consecutive
 	// objects starting with the first page object.  The rest are
 	// consecutive starting from the first_shared_obj object.
-	int cur_object = pages[0].getObjectID();
+	int cur_object = pages.at(0).getObjectID();
 	for (int i = 0; i < so.nshared_total; ++i)
 	{
 	    if (i == so.nshared_first_page)
@@ -937,7 +937,7 @@ QPDF::checkHSharedObject(std::list&lt;std::string&gt;&amp; errors,
 		}
 		else
 		{
-		    int obj = this->part8[0].getObjectID();
+		    int obj = this->part8.at(0).getObjectID();
 		    if (obj != so.first_shared_obj)
 		    {
 			errors.push_back(
@@ -965,7 +965,7 @@ QPDF::checkHSharedObject(std::list&lt;std::string&gt;&amp; errors,
 	    }
 	    idx_to_obj[i] = cur_object;
-	    HSharedObjectEntry& se = so.entries[i];
+	    HSharedObjectEntry& se = so.entries.at(i);
 	    int nobjects = se.nobjects_minus_one + 1;
 	    int length = lengthNextN(cur_object, nobjects, errors);
 	    int h_length = so.min_group_length + se.delta_group_length;
@@ -1146,7 +1146,7 @@ QPDF::dumpHPageOffset()
     for (int i1 = 0; i1 < this->linp.npages; ++i1)
     {
-	HPageOffsetEntry& pe = t.entries[i1];
+	HPageOffsetEntry& pe = t.entries.at(i1);
 	*out_stream
 	    << "Page " << i1 << ":" << std::endl
 	    << "  nobjects: " << pe.delta_nobjects + t.min_nobjects
@@ -1162,9 +1162,9 @@ QPDF::dumpHPageOffset()
 	for (int i2 = 0; i2 < pe.nshared_objects; ++i2)
 	{
 	    *out_stream << "    identifier " << i2 << ": "
-			<< pe.shared_identifiers[i2] << std::endl;
+			<< pe.shared_identifiers.at(i2) << std::endl;
 	    *out_stream << "    numerator " << i2 << ": "
-			<< pe.shared_numerators[i2] << std::endl;
+			<< pe.shared_numerators.at(i2) << std::endl;
 	}
     }
 }
@@ -1191,7 +1191,7 @@ QPDF::dumpHSharedObject()
     for (int i = 0; i < t.nshared_total; ++i)
     {
-	HSharedObjectEntry& se = t.entries[i];
+	HSharedObjectEntry& se = t.entries.at(i);
 	*out_stream << "Shared Object " << i << ":" << std::endl;
 	*out_stream << "  group length: "
 		    << se.delta_group_length + t.min_group_length << std::endl;
@@ -1522,7 +1522,7 @@ QPDF::calculateLinearizationData(std::map&lt;int, int&gt; const&amp; object_stream_data)
     // will do the same.
     // First, place the actual first page object itself.
-    QPDFObjGen first_page_og(pages[0].getObjGen());
+    QPDFObjGen first_page_og(pages.at(0).getObjGen());
     if (! lc_first_page_private.count(first_page_og))
     {
 	throw std::logic_error(
@@ -1530,8 +1530,8 @@ QPDF::calculateLinearizationData(std::map&lt;int, int&gt; const&amp; object_stream_data)
 	    "object not in lc_first_page_private");
     }
     lc_first_page_private.erase(first_page_og);
-    this->c_linp.first_page_object = pages[0].getObjectID();
-    this->part6.push_back(pages[0]);
+    this->c_linp.first_page_object = pages.at(0).getObjectID();
+    this->part6.push_back(pages.at(0));
     // The PDF spec "recommends" an order for the rest of the objects,
     // but we are going to disregard it except to the extent that it
@@ -1562,7 +1562,7 @@ QPDF::calculateLinearizationData(std::map&lt;int, int&gt; const&amp; object_stream_data)
     // in garbage values for all the shared object identifiers on the
     // first page.
-    this->c_page_offset_data.entries[0].nobjects = this->part6.size();
+    this->c_page_offset_data.entries.at(0).nobjects = this->part6.size();
     // Part 7: other pages' private objects
@@ -1571,7 +1571,7 @@ QPDF::calculateLinearizationData(std::map&lt;int, int&gt; const&amp; object_stream_data)
     {
 	// Place this page's page object
-	QPDFObjGen page_og(pages[i].getObjGen());
+	QPDFObjGen page_og(pages.at(i).getObjGen());
 	if (! lc_other_page_private.count(page_og))
 	{
 	    throw std::logic_error(
@@ -1580,12 +1580,12 @@ QPDF::calculateLinearizationData(std::map&lt;int, int&gt; const&amp; object_stream_data)
 		QUtil::int_to_string(i) + " not in lc_other_page_private");
 	}
 	lc_other_page_private.erase(page_og);
-	this->part7.push_back(pages[i]);
+	this->part7.push_back(pages.at(i));
 	// Place all non-shared objects referenced by this page,
 	// updating the page object count for the hint table.
-	this->c_page_offset_data.entries[i].nobjects = 1;
+	this->c_page_offset_data.entries.at(i).nobjects = 1;
 	ObjUser ou(ObjUser::ou_page, i);
 	assert(this->obj_user_to_objects.count(ou) > 0);
@@ -1598,7 +1598,7 @@ QPDF::calculateLinearizationData(std::map&lt;int, int&gt; const&amp; object_stream_data)
 	    {
 		lc_other_page_private.erase(og);
 		this->part7.push_back(objGenToIndirect(og));
-		++this->c_page_offset_data.entries[i].nobjects;
+		++this->c_page_offset_data.entries.at(i).nobjects;
 	    }
 	}
     }
@@ -1649,7 +1649,7 @@ QPDF::calculateLinearizationData(std::map&lt;int, int&gt; const&amp; object_stream_data)
     // thumbnail hint tables.
     for (unsigned int i = 0; i < npages; ++i)
     {
-	QPDFObjectHandle thumb = pages[i].getKey("/Thumb");
+	QPDFObjectHandle thumb = pages.at(i).getKey("/Thumb");
 	thumb = getUncompressedObject(thumb, object_stream_data);
 	if (! thumb.isNull())
 	{
@@ -1758,7 +1758,7 @@ QPDF::calculateLinearizationData(std::map&lt;int, int&gt; const&amp; object_stream_data)
     if (! this->part8.empty())
     {
 	this->c_shared_object_data.first_shared_obj =
-	    this->part8[0].getObjectID();
+	    this->part8.at(0).getObjectID();
 	for (std::vector<QPDFObjectHandle>::iterator iter =
 		 this->part8.begin();
 	     iter != this->part8.end(); ++iter)
@@ -1781,7 +1781,7 @@ QPDF::calculateLinearizationData(std::map&lt;int, int&gt; const&amp; object_stream_data)
     for (unsigned int i = 1; i < npages; ++i)
     {
-	CHPageOffsetEntry& pe = this->c_page_offset_data.entries[i];
+	CHPageOffsetEntry& pe = this->c_page_offset_data.entries.at(i);
 	ObjUser ou(ObjUser::ou_page, i);
 	assert(this->obj_user_to_objects.count(ou) > 0);
 	std::set<QPDFObjGen> const& ogs = this->obj_user_to_objects[ou];
@@ -1892,12 +1892,12 @@ QPDF::calculateHPageOffset(
     // Calculate minimum and maximum values for number of objects per
     // page and page length.
-    int min_nobjects = cphe[0].nobjects;
+    int min_nobjects = cphe.at(0).nobjects;
     int max_nobjects = min_nobjects;
     int min_length = outputLengthNextN(
-	pages[0].getObjectID(), min_nobjects, lengths, obj_renumber);
+	pages.at(0).getObjectID(), min_nobjects, lengths, obj_renumber);
     int max_length = min_length;
-    int max_shared = cphe[0].nshared_objects;
+    int max_shared = cphe.at(0).nshared_objects;
     HPageOffset& ph = this->page_offset_hints;
     std::vector<HPageOffsetEntry>& phe = ph.entries;
@@ -1912,10 +1912,10 @@ QPDF::calculateHPageOffset(
 	// Repeat calculations for page 0 so we can assign to phe[i]
 	// without duplicating those assignments.
-	int nobjects = cphe[i].nobjects;
+	int nobjects = cphe.at(i).nobjects;
 	int length = outputLengthNextN(
-	    pages[i].getObjectID(), nobjects, lengths, obj_renumber);
-	int nshared = cphe[i].nshared_objects;
+	    pages.at(i).getObjectID(), nobjects, lengths, obj_renumber);
+	int nshared = cphe.at(i).nshared_objects;
 	min_nobjects = std::min(min_nobjects, nobjects);
 	max_nobjects = std::max(max_nobjects, nobjects);
@@ -1923,13 +1923,13 @@ QPDF::calculateHPageOffset(
 	max_length = std::max(max_length, length);
 	max_shared = std::max(max_shared, nshared);
-	phe[i].delta_nobjects = nobjects;
-	phe[i].delta_page_length = length;
-	phe[i].nshared_objects = nshared;
+	phe.at(i).delta_nobjects = nobjects;
+	phe.at(i).delta_page_length = length;
+	phe.at(i).nshared_objects = nshared;
     }
     ph.min_nobjects = min_nobjects;
-    int in_page0_id = pages[0].getObjectID();
+    int in_page0_id = pages.at(0).getObjectID();
     int out_page0_id = (*(obj_renumber.find(in_page0_id))).second;
     ph.first_page_offset = (*(xref.find(out_page0_id))).second.getOffset();
     ph.nbits_delta_nobjects = nbits(max_nobjects - min_nobjects);
@@ -1951,17 +1951,17 @@ QPDF::calculateHPageOffset(
     for (unsigned int i = 0; i < npages; ++i)
     {
 	// Adjust delta entries
-	assert(phe[i].delta_nobjects >= min_nobjects);
-	assert(phe[i].delta_page_length >= min_length);
-	phe[i].delta_nobjects -= min_nobjects;
-	phe[i].delta_page_length -= min_length;
-	phe[i].delta_content_length = phe[i].delta_page_length;
+	assert(phe.at(i).delta_nobjects >= min_nobjects);
+	assert(phe.at(i).delta_page_length >= min_length);
+	phe.at(i).delta_nobjects -= min_nobjects;
+	phe.at(i).delta_page_length -= min_length;
+	phe.at(i).delta_content_length = phe.at(i).delta_page_length;
-	for (int j = 0; j < cphe[i].nshared_objects; ++j)
+	for (int j = 0; j < cphe.at(i).nshared_objects; ++j)
 	{
-	    phe[i].shared_identifiers.push_back(
-		cphe[i].shared_identifiers[j]);
-	    phe[i].shared_numerators.push_back(0);
+	    phe.at(i).shared_identifiers.push_back(
+		cphe.at(i).shared_identifiers.at(j));
+	    phe.at(i).shared_numerators.push_back(0);
 	}
     }
 }
@@ -1979,18 +1979,18 @@ QPDF::calculateHSharedObject(
     soe.clear();
     int min_length = outputLengthNextN(
-	csoe[0].object, 1, lengths, obj_renumber);
+	csoe.at(0).object, 1, lengths, obj_renumber);
     int max_length = min_length;
     for (int i = 0; i < cso.nshared_total; ++i)
     {
 	// Assign absolute numbers to deltas; adjust later
 	int length = outputLengthNextN(
-	    csoe[i].object, 1, lengths, obj_renumber);
+	    csoe.at(i).object, 1, lengths, obj_renumber);
 	min_length = std::min(min_length, length);
 	max_length = std::max(max_length, length);
         soe.push_back(HSharedObjectEntry());
-	soe[i].delta_group_length = length;
+	soe.at(i).delta_group_length = length;
     }
     if (soe.size() != static_cast<size_t>(cso.nshared_total))
     {
@@ -2012,8 +2012,8 @@ QPDF::calculateHSharedObject(
     for (int i = 0; i < cso.nshared_total; ++i)
     {
 	// Adjust deltas
-	assert(soe[i].delta_group_length >= min_length);
-	soe[i].delta_group_length -= min_length;
+	assert(soe.at(i).delta_group_length >= min_length);
+	soe.at(i).delta_group_length -= min_length;
     }
 }
@@ -2051,7 +2051,7 @@ write_vector_int(BitWriter&amp; w, int nitems, std::vector&lt;T&gt;&amp; vec,
     for (int i = 0; i < nitems; ++i)
     {
-	w.writeBits(vec[i].*field, bits);
+	w.writeBits(vec.at(i).*field, bits);
     }
     // The PDF spec says that each hint table starts at a byte
     // boundary.  Each "row" actually must start on a byte boundary.
@@ -2068,9 +2068,9 @@ write_vector_vector(BitWriter&amp; w,
     // from the vec2 vector field of the ith item of vec1.
     for (int i1 = 0; i1 < nitems1; ++i1)
     {
-	for (int i2 = 0; i2 < vec1[i1].*nitems2; ++i2)
+	for (int i2 = 0; i2 < vec1.at(i1).*nitems2; ++i2)
 	{
-	    w.writeBits((vec1[i1].*vec2)[i2], bits);
+	    w.writeBits((vec1.at(i1).*vec2).at(i2), bits);
 	}
     }
     w.flush();
@@ -2151,7 +2151,7 @@ QPDF::writeHSharedObject(BitWriter&amp; w)
     for (int i = 0; i < nitems; ++i)
     {
 	// If signature were present, we'd have to write a 128-bit hash.
-	assert(entries[i].signature_present == 0);
+	assert(entries.at(i).signature_present == 0);
     }
     write_vector_int(w, nitems, entries,
 		     t.nbits_nobjects,
@@ -91,7 +91,7 @@ QPDF::optimize(std::map&lt;int, int&gt; const&amp; object_stream_data,
     for (int pageno = 0; pageno < n; ++pageno)
     {
         updateObjectMaps(ObjUser(ObjUser::ou_page, pageno),
-                         this->all_pages[pageno]);
+                         this->all_pages.at(pageno));
     }
     // Traverse document-level items
@@ -114,8 +114,8 @@ QPDF::flattenPagesTree()
     for (int pos = 0; pos < len; ++pos)
     {
         // populate pageobj_to_pages_pos and fix parent pointer
-        insertPageobjToPage(this->all_pages[pos], pos, true);
-        this->all_pages[pos].replaceKey("/Parent", pages);
+        insertPageobjToPage(this->all_pages.at(pos), pos, true);
+        this->all_pages.at(pos).replaceKey("/Parent", pages);
     }
     pages.replaceKey("/Kids", QPDFObjectHandle::newArray(this->all_pages));
@@ -194,7 +194,7 @@ QPDF::insertPage(QPDFObjectHandle newpage, int pos)
     assert(this->all_pages.size() == static_cast<size_t>(npages));
     for (int i = pos + 1; i < npages; ++i)
     {
-        insertPageobjToPage(this->all_pages[i], i, false);
+        insertPageobjToPage(this->all_pages.at(i), i, false);
     }
     insertPageobjToPage(newpage, pos, true);
     assert(this->pageobj_to_pages_pos.size() == static_cast<size_t>(npages));
@@ -221,7 +221,7 @@ QPDF::removePage(QPDFObjectHandle page)
     assert(this->pageobj_to_pages_pos.size() == static_cast<size_t>(npages));
     for (int i = pos; i < npages; ++i)
     {
-        insertPageobjToPage(this->all_pages[i], i, false);
+        insertPageobjToPage(this->all_pages.at(i), i, false);
     }
 }
@@ -201,7 +201,7 @@ QUtil::hex_encode(std::string const&amp; input)
     for (unsigned int i = 0; i < input.length(); ++i)
     {
         result += QUtil::int_to_string_base(
-            static_cast<int>(static_cast<unsigned char>(input[i])), 16, 2);
+            static_cast<int>(static_cast<unsigned char>(input.at(i))), 16, 2);
     }
     return result;
 }
@@ -441,7 +441,7 @@ static std::vector&lt;int&gt; parse_numrange(char const* range, int max,
         p = 0;
         for (size_t i = 0; i < work.size(); i += 2)
         {
-            int num = work[i];
+            int num = work.at(i);
             // max == 0 means we don't know the max and are just
             // testing for valid syntax.
             if ((max > 0) && ((num < 1) || (num > max)))
@@ -451,11 +451,11 @@ static std::vector&lt;int&gt; parse_numrange(char const* range, int max,
             }
             if (i == 0)
             {
-                result.push_back(work[i]);
+                result.push_back(work.at(i));
             }
             else
             {
-                int separator = work[i-1];
+                int separator = work.at(i-1);
                 if (separator == comma)
                 {
                     result.push_back(num);
@@ -1664,7 +1664,7 @@ int main(int argc, char* argv[])
                         // Pages are specified from 1 but numbered
                         // from 0 in the vector
                         int pageno = *pageno_iter - 1;
-                        pdf.addPage(page_data.orig_pages[pageno], false);
+                        pdf.addPage(page_data.orig_pages.at(pageno), false);
                         if (page_data.qpdf == &pdf)
                         {
                             // This is a page from the original file.
@@ -1683,7 +1683,7 @@ int main(int argc, char* argv[])
                 {
                     if (selected_from_orig.count(pageno) == 0)
                     {
-                        pdf.replaceObject(orig_pages[pageno].getObjGen(),
+                        pdf.replaceObject(orig_pages.at(pageno).getObjGen(),
                                           QPDFObjectHandle::newNull());
                     }
                 }
@@ -603,10 +603,10 @@ void runtest(int n, char const* filename1, char const* arg2)
     else if (n == 10)
     {
 	std::vector<QPDFObjectHandle> pages = pdf.getAllPages();
-	pages[0].addPageContents(
+	pages.at(0).addPageContents(
             QPDFObjectHandle::newStream(
                 &pdf, "BT /F1 12 Tf 72 620 Td (Baked) Tj ET\n"), true);
-	pages[0].addPageContents(
+	pages.at(0).addPageContents(
             QPDFObjectHandle::newStream(
                 &pdf, "BT /F1 18 Tf 72 520 Td (Mashed) Tj ET\n"), false);
@@ -659,7 +659,7 @@ void runtest(int n, char const* filename1, char const* arg2)
 				   " not called 4-page file");
 	}
 	// Swap pages 2 and 3
-	pdf.swapObjects(pages[1].getObjGen(), pages[2].getObjGen());
+	pdf.swapObjects(pages.at(1).getObjGen(), pages.at(2).getObjGen());
 	// Replace object and swap objects
 	QPDFObjectHandle trailer = pdf.getTrailer();
 	QPDFObjectHandle qdict = trailer.getKey("/QDict");
@@ -700,7 +700,7 @@ void runtest(int n, char const* filename1, char const* arg2)
 	std::map<std::string, QPDFObjectHandle> dict_items =
 	    qarray.getDictAsMap();
 	if ((array_elements.size() == 1) &&
-	    (array_elements[0].getName() == "/Array") &&
+	    (array_elements.at(0).getName() == "/Array") &&
 	    (dict_items.size() == 1) &&
 	    (dict_items["/NewDict"].getIntValue() == 2))
 	{
@@ -738,12 +738,12 @@ void runtest(int n, char const* filename1, char const* arg2)
         assert(pages.size() == 9);
         pdf.removePage(*pages.begin()); // original page 0
         assert(pages.size() == 8);
-        checkPageContents(pages[4], "Original page 5");
-        pdf.removePage(pages[4]); // original page 5
+        checkPageContents(pages.at(4), "Original page 5");
+        pdf.removePage(pages.at(4)); // original page 5
         assert(pages.size() == 7);
-        checkPageContents(pages[4], "Original page 6");
-        checkPageContents(pages[0], "Original page 1");
-        checkPageContents(pages[6], "Original page 8");
+        checkPageContents(pages.at(4), "Original page 6");
+        checkPageContents(pages.at(0), "Original page 1");
+        checkPageContents(pages.at(6), "Original page 8");
         // Insert pages
@@ -760,7 +760,7 @@ void runtest(int n, char const* filename1, char const* arg2)
         // dictionary and modify it.  Using the results of
         // getDictAsMap to create a new dictionary effectively creates
         // a shallow copy.
-        QPDFObjectHandle page_template = pages[0];
+        QPDFObjectHandle page_template = pages.at(0);
         std::vector<QPDFObjectHandle> new_pages;
         for (std::vector<QPDFObjectHandle>::iterator iter = contents.begin();
              iter != contents.end(); ++iter)
@@ -781,25 +781,25 @@ void runtest(int n, char const* filename1, char const* arg2)
         }
         // Now insert the pages
-        pdf.addPage(new_pages[0], true);
-        checkPageContents(pages[0], "New page 1");
-        pdf.addPageAt(new_pages[1], true, pages[0]);
-        assert(pages[0].getObjGen() == new_pages[1].getObjGen());
-        pdf.addPageAt(new_pages[2], true, pages[5]);
-        assert(pages[5].getObjGen() == new_pages[2].getObjGen());
-        pdf.addPageAt(new_pages[3], false, pages[5]);
-        assert(pages[6].getObjGen() == new_pages[3].getObjGen());
+        pdf.addPage(new_pages.at(0), true);
+        checkPageContents(pages.at(0), "New page 1");
+        pdf.addPageAt(new_pages.at(1), true, pages.at(0));
+        assert(pages.at(0).getObjGen() == new_pages.at(1).getObjGen());
+        pdf.addPageAt(new_pages.at(2), true, pages.at(5));
+        assert(pages.at(5).getObjGen() == new_pages.at(2).getObjGen());
+        pdf.addPageAt(new_pages.at(3), false, pages.at(5));
+        assert(pages.at(6).getObjGen() == new_pages.at(3).getObjGen());
         assert(pages.size() == 11);
-        pdf.addPage(new_pages[4], false);
-        assert(pages[11].getObjGen() == new_pages[4].getObjGen());
-        pdf.addPageAt(new_pages[5], false, pages.back());
+        pdf.addPage(new_pages.at(4), false);
+        assert(pages.at(11).getObjGen() == new_pages.at(4).getObjGen());
+        pdf.addPageAt(new_pages.at(5), false, pages.back());
         assert(pages.size() == 13);
-        checkPageContents(pages[0], "New page 0");
-        checkPageContents(pages[1], "New page 1");
-        checkPageContents(pages[5], "New page 5");
-        checkPageContents(pages[6], "New page 6");
-        checkPageContents(pages[11], "New page 11");
-        checkPageContents(pages[12], "New page 12");
+        checkPageContents(pages.at(0), "New page 0");
+        checkPageContents(pages.at(1), "New page 1");
+        checkPageContents(pages.at(5), "New page 5");
+        checkPageContents(pages.at(6), "New page 6");
+        checkPageContents(pages.at(11), "New page 11");
+        checkPageContents(pages.at(12), "New page 12");
         // Exercise writing to FILE*
         FILE* out =  QUtil::safe_fopen("a.pdf", "wb");
@@ -816,7 +816,7 @@ void runtest(int n, char const* filename1, char const* arg2)
         QPDFObjectHandle contents = createPageContents(pdf, "New page 10");
         QPDFObjectHandle page =
             pdf.makeIndirectObject(
-                QPDFObjectHandle(all_pages[0]).shallowCopy());
+                QPDFObjectHandle(all_pages.at(0)).shallowCopy());
         page.replaceKey("/Contents", contents);
         // Insert the page manually.
@@ -843,7 +843,7 @@ void runtest(int n, char const* filename1, char const* arg2)
         // The input file to this test case is broken to exercise an
         // error condition.
         std::vector<QPDFObjectHandle> const& pages = pdf.getAllPages();
-        pdf.removePage(pages[0]);
+        pdf.removePage(pages.at(0));
         std::cout << "you can't see this" << std::endl;
     }
     else if (n == 18)
@@ -854,7 +854,7 @@ void runtest(int n, char const* filename1, char const* arg2)
         // Remove pages from various places, checking to make sure
         // that our pages reference is getting updated.
         assert(pages.size() == 10);
-        QPDFObjectHandle page5 = pages[5];
+        QPDFObjectHandle page5 = pages.at(5);
         pdf.removePage(page5);
         pdf.addPage(page5, false);
         assert(pages.size() == 10);
@@ -871,7 +871,7 @@ void runtest(int n, char const* filename1, char const* arg2)
         std::vector<QPDFObjectHandle> const& pages = pdf.getAllPages();
         // Try to insert a page that's already there.
-        pdf.addPage(pages[5], false);
+        pdf.addPage(pages.at(5), false);
         std::cout << "you can't see this" << std::endl;
     }
     else if (n == 20)
@@ -893,7 +893,7 @@ void runtest(int n, char const* filename1, char const* arg2)
     {
         // Try to shallow copy a stream
         std::vector<QPDFObjectHandle> const& pages = pdf.getAllPages();
-        QPDFObjectHandle page = pages[0];
+        QPDFObjectHandle page = pages.at(0);
         QPDFObjectHandle contents = page.getKey("/Contents");
         contents.shallowCopy();
         std::cout << "you can't see this" << std::endl;
@@ -902,7 +902,7 @@ void runtest(int n, char const* filename1, char const* arg2)
     {
         // Try to remove a page we don't have
         std::vector<QPDFObjectHandle> const& pages = pdf.getAllPages();
-        QPDFObjectHandle page = pages[0];
+        QPDFObjectHandle page = pages.at(0);
         pdf.removePage(page);
         pdf.removePage(page);
         std::cout << "you can't see this" << std::endl;
@@ -1109,9 +1109,9 @@ void runtest(int n, char const* filename1, char const* arg2)
         QPDF final;
         final.processFile("b.pdf", "user");
         std::vector<QPDFObjectHandle> pages = pdf.getAllPages();
-        std::string orig_contents = getPageContents(pages[0]);
+        std::string orig_contents = getPageContents(pages.at(0));
         pages = final.getAllPages();
-        std::string new_contents = getPageContents(pages[0]);
+        std::string new_contents = getPageContents(pages.at(0));
         if (orig_contents != new_contents)
         {
             std::cout << "oops -- page contents don't match" << std::endl
@@ -1226,7 +1226,7 @@ void runtest(int n, char const* filename1, char const* arg2)
             bool is_binary = false;
             for (size_t i = 0; i < data.size(); ++i)
             {
-                if ((data[i] < 0) || (data[i] > 126))
+                if ((data.at(i) < 0) || (data.at(i) > 126))
                 {
                     is_binary = true;
                     break;
@@ -1239,9 +1239,9 @@ void runtest(int n, char const* filename1, char const* arg2)
                      i < std::min(data.size(), static_cast<size_t>(20));
                      ++i)
                 {
-                    if ((data[i] >= 32) && (data[i] <= 126))
+                    if ((data.at(i) >= 32) && (data.at(i) <= 126))
                     {
-                        t += data[i];
+                        t += data.at(i);
                     }
                     else
                     {
@@ -286,8 +286,8 @@ static void check_pdf(char const* filename)
     {
         int pageno = i + 1;
         std::cout << "page " << pageno << " of " << npages << std::endl;
-        check_page_contents(pageno, pages[i]);
-        check_image(pageno, pages[i]);
+        check_page_contents(pageno, pages.at(i));
+        check_image(pageno, pages.at(i));
     }
 }