3 files changed, 50 insertions, 2 deletions
diff --git a/Source/cmFileCommand.cxx b/Source/cmFileCommand.cxx
index 7810040..bec9fb2 100644
--- a/Source/cmFileCommand.cxx
+++ b/Source/cmFileCommand.cxx
@@ -201,13 +201,19 @@ bool HandleReadCommand(std::vector<std::string> const& args,
   // is there a limit?
   std::string::size_type sizeLimit = std::string::npos;
   if (!arguments.Limit.empty()) {
-    std::istringstream(arguments.Limit) >> sizeLimit;
+    unsigned long long limit;
+    if (cmStrToULongLong(arguments.Limit, &limit)) {
+      sizeLimit = static_cast<std::string::size_type>(limit);
+    }
   }
 
   // is there an offset?
   cmsys::ifstream::off_type offset = 0;
   if (!arguments.Offset.empty()) {
-    std::istringstream(arguments.Offset) >> offset;
+    long long off;
+    if (cmStrToLongLong(arguments.Offset, &off)) {
+      offset = static_cast<cmsys::ifstream::off_type>(off);
+    }
   }
 
   file.seekg(offset, std::ios::beg); // explicit ios::beg for IBM VisualAge 6
diff --git a/Source/cmStringAlgorithms.cxx b/Source/cmStringAlgorithms.cxx
index 1bb6808..f73c854 100644
--- a/Source/cmStringAlgorithms.cxx
+++ b/Source/cmStringAlgorithms.cxx
@@ -250,6 +250,38 @@ bool cmStrToULong(std::string const& str, unsigned long* value)
   return cmStrToULong(str.c_str(), value);
 }
 
+bool cmStrToLongLong(const char* str, long long* value)
+{
+  errno = 0;
+  char* endp;
+  *value = strtoll(str, &endp, 10);
+  return (*endp == '\0') && (endp != str) && (errno == 0);
+}
+
+bool cmStrToLongLong(std::string const& str, long long* value)
+{
+  return cmStrToLongLong(str.c_str(), value);
+}
+
+bool cmStrToULongLong(const char* str, unsigned long long* value)
+{
+  errno = 0;
+  char* endp;
+  while (cmIsSpace(*str)) {
+    ++str;
+  }
+  if (*str == '-') {
+    return false;
+  }
+  *value = strtoull(str, &endp, 10);
+  return (*endp == '\0') && (endp != str) && (errno == 0);
+}
+
+bool cmStrToULongLong(std::string const& str, unsigned long long* value)
+{
+  return cmStrToULongLong(str.c_str(), value);
+}
+
 template <typename Range>
 std::size_t getJoinedLength(Range const& rng, cm::string_view separator)
 {
diff --git a/Source/cmStringAlgorithms.h b/Source/cmStringAlgorithms.h
index 492e588..83938bc 100644
--- a/Source/cmStringAlgorithms.h
+++ b/Source/cmStringAlgorithms.h
@@ -303,3 +303,13 @@ bool cmStrToLong(std::string const& str, long* value);
  * integer */
 bool cmStrToULong(const char* str, unsigned long* value);
 bool cmStrToULong(std::string const& str, unsigned long* value);
+
+/** Converts a string to long long. Expects that the whole string
+ * is an integer */
+bool cmStrToLongLong(const char* str, long long* value);
+bool cmStrToLongLong(std::string const& str, long long* value);
+
+/** Converts a string to unsigned long long. Expects that the whole string
+ * is an integer */
+bool cmStrToULongLong(const char* str, unsigned long long* value);
+bool cmStrToULongLong(std::string const& str, unsigned long long* value);