1// Copyright (c) 2008, Google Inc.
2// All rights reserved.
3//
4// Redistribution and use in source and binary forms, with or without
5// modification, are permitted provided that the following conditions are
6// met:
7//
8//     * Redistributions of source code must retain the above copyright
9// notice, this list of conditions and the following disclaimer.
10//     * Redistributions in binary form must reproduce the above
11// copyright notice, this list of conditions and the following disclaimer
12// in the documentation and/or other materials provided with the
13// distribution.
14//     * Neither the name of Google Inc. nor the names of its
15// contributors may be used to endorse or promote products derived from
16// this software without specific prior written permission.
17//
18// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
19// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
20// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
21// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
22// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
23// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
24// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
25// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
26// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
27// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
28// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
29
30// ---
31// Author: Sanjay Ghemawat
32//
33// A printf() wrapper that writes into a fixed length buffer.
34// Useful in low-level code that does not want to use allocating
35// routines like StringPrintf().
36//
37// The implementation currently uses vsnprintf().  This seems to
38// be fine for use in many low-level contexts, but we may need to
39// rethink this decision if we hit a problem with it calling
40// down into malloc() etc.
41
42#ifndef BASE_RAW_PRINTER_H_
43#define BASE_RAW_PRINTER_H_
44
45#include <config.h>
46#include "base/basictypes.h"
47
48namespace base {
49
50class RawPrinter {
51 public:
52  // REQUIRES: "length > 0"
53  // Will printf any data added to this into "buf[0,length-1]" and
54  // will arrange to always keep buf[] null-terminated.
55  RawPrinter(char* buf, int length);
56
57  // Return the number of bytes that have been appended to the string
58  // so far.  Does not count any bytes that were dropped due to overflow.
59  int length() const { return (ptr_ - base_); }
60
61  // Return the number of bytes that can be added to this.
62  int space_left() const { return (limit_ - ptr_); }
63
64  // Format the supplied arguments according to the "format" string
65  // and append to this.  Will silently truncate the output if it does
66  // not fit.
67  void Printf(const char* format, ...)
68#ifdef HAVE___ATTRIBUTE__
69  __attribute__ ((__format__ (__printf__, 2, 3)))
70#endif
71;
72
73 private:
74  // We can write into [ptr_ .. limit_-1].
75  // *limit_ is also writable, but reserved for a terminating \0
76  // in case we overflow.
77  //
78  // Invariants: *ptr_ == \0
79  // Invariants: *limit_ == \0
80  char* base_;          // Initial pointer
81  char* ptr_;           // Where should we write next
82  char* limit_;         // One past last non-\0 char we can write
83
84  DISALLOW_COPY_AND_ASSIGN(RawPrinter);
85};
86
87}
88
89#endif  // BASE_RAW_PRINTER_H_
90