1 //===-- VASprintf.cpp -----------------------------------------------------===//
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 <cassert>
16 #include <cstdarg>
17 #include <cstdio>
18
VASprintf(llvm::SmallVectorImpl<char> & buf,const char * fmt,va_list args)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