1 //===-- VASprintf.cpp -------------------------------------------*- C++ -*-===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 
9 #include "lldb/Utility/VASPrintf.h"
10 
11 #include "llvm/ADT/SmallString.h"
12 #include "llvm/ADT/SmallVector.h"
13 #include "llvm/ADT/StringRef.h"
14 
15 #include <assert.h>
16 #include <stdarg.h>
17 #include <stdio.h>
18 
19 bool lldb_private::VASprintf(llvm::SmallVectorImpl<char> &buf, const char *fmt,
20                              va_list args) {
21   llvm::SmallString<16> error("<Encoding error>");
22   bool result = true;
23 
24   // Copy in case our first call to vsnprintf doesn't fit into our buffer
25   va_list copy_args;
26   va_copy(copy_args, args);
27 
28   buf.resize(buf.capacity());
29   // Write up to `capacity` bytes, ignoring the current size.
30   int length = ::vsnprintf(buf.data(), buf.size(), fmt, args);
31   if (length < 0) {
32     buf = error;
33     result = false;
34     goto finish;
35   }
36 
37   if (size_t(length) >= buf.size()) {
38     // The error formatted string didn't fit into our buffer, resize it to the
39     // exact needed size, and retry
40     buf.resize(length + 1);
41     length = ::vsnprintf(buf.data(), buf.size(), fmt, copy_args);
42     if (length < 0) {
43       buf = error;
44       result = false;
45       goto finish;
46     }
47     assert(size_t(length) < buf.size());
48   }
49   buf.resize(length);
50 
51 finish:
52   va_end(args);
53   va_end(copy_args);
54   return result;
55 }
56