1 files changed, 85 insertions, 0 deletions
diff --git a/tensorflow/core/lib/strings/stringprintf.cc b/tensorflow/core/lib/strings/stringprintf.cc
new file mode 100644
index 0000000000..b354706cbd
--- /dev/null
+++ b/tensorflow/core/lib/strings/stringprintf.cc
@@ -0,0 +1,85 @@
+#include "tensorflow/core/lib/strings/stringprintf.h"
+
+#include <errno.h>
+#include <stdarg.h>  // For va_list and related operations
+#include <stdio.h>   // MSVC requires this for _vsnprintf
+#include <vector>
+
+namespace tensorflow {
+namespace strings {
+
+#ifdef COMPILER_MSVC
+enum { IS_COMPILER_MSVC = 1 };
+#else
+enum { IS_COMPILER_MSVC = 0 };
+#endif
+
+void Appendv(string* dst, const char* format, va_list ap) {
+  // First try with a small fixed size buffer
+  static const int kSpaceLength = 1024;
+  char space[kSpaceLength];
+
+  // It's possible for methods that use a va_list to invalidate
+  // the data in it upon use.  The fix is to make a copy
+  // of the structure before using it and use that copy instead.
+  va_list backup_ap;
+  va_copy(backup_ap, ap);
+  int result = vsnprintf(space, kSpaceLength, format, backup_ap);
+  va_end(backup_ap);
+
+  if (result < kSpaceLength) {
+    if (result >= 0) {
+      // Normal case -- everything fit.
+      dst->append(space, result);
+      return;
+    }
+
+    if (IS_COMPILER_MSVC) {
+      // Error or MSVC running out of space.  MSVC 8.0 and higher
+      // can be asked about space needed with the special idiom below:
+      va_copy(backup_ap, ap);
+      result = vsnprintf(NULL, 0, format, backup_ap);
+      va_end(backup_ap);
+    }
+
+    if (result < 0) {
+      // Just an error.
+      return;
+    }
+  }
+
+  // Increase the buffer size to the size requested by vsnprintf,
+  // plus one for the closing \0.
+  int length = result + 1;
+  char* buf = new char[length];
+
+  // Restore the va_list before we use it again
+  va_copy(backup_ap, ap);
+  result = vsnprintf(buf, length, format, backup_ap);
+  va_end(backup_ap);
+
+  if (result >= 0 && result < length) {
+    // It fit
+    dst->append(buf, result);
+  }
+  delete[] buf;
+}
+
+string Printf(const char* format, ...) {
+  va_list ap;
+  va_start(ap, format);
+  string result;
+  Appendv(&result, format, ap);
+  va_end(ap);
+  return result;
+}
+
+void Appendf(string* dst, const char* format, ...) {
+  va_list ap;
+  va_start(ap, format);
+  Appendv(dst, format, ap);
+  va_end(ap);
+}
+
+}  // namespace strings
+}  // namespace tensorflow