1 /*
   2  * Copyright (c) 2017, 2018, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #ifndef SHARE_VM_UTILITIES_FORMATBUFFER_HPP
  26 #define SHARE_VM_UTILITIES_FORMATBUFFER_HPP
  27 
  28 #include "jvm.h"
  29 #include "utilities/globalDefinitions.hpp"
  30 #include <stdarg.h>
  31 
  32 // Simple class to format the ctor arguments into a fixed-sized buffer.
  33 class FormatBufferBase {
  34  protected:
  35   char* _buf;
  36   inline FormatBufferBase(char* buf) : _buf(buf) {}
  37  public:
  38   static const int BufferSize = 256;
  39   operator const char *() const { return _buf; }
  40 };
  41 
  42 // Use resource area for buffer
  43 class FormatBufferResource : public FormatBufferBase {
  44  public:
  45   FormatBufferResource(const char * format, ...) ATTRIBUTE_PRINTF(2, 3);
  46 };
  47 
  48 class FormatBufferDummy {};
  49 
  50 // Use stack for buffer
  51 template <size_t bufsz = FormatBufferBase::BufferSize>
  52 class FormatBuffer : public FormatBufferBase {
  53  public:
  54   inline FormatBuffer(const char* format, ...) ATTRIBUTE_PRINTF(2, 3);
  55   // since va_list is unspecified type (can be char*), we use FormatBufferDummy to disambiguate these constructors
  56   inline FormatBuffer(FormatBufferDummy dummy, const char* format, va_list ap) ATTRIBUTE_PRINTF(3, 0);
  57   inline void append(const char* format, ...)  ATTRIBUTE_PRINTF(2, 3);
  58   inline void print(const char* format, ...)  ATTRIBUTE_PRINTF(2, 3);
  59   inline void printv(const char* format, va_list ap) ATTRIBUTE_PRINTF(2, 0);
  60 
  61   char* buffer() { return _buf; }
  62   int size() { return bufsz; }
  63 
  64  private:
  65   FormatBuffer(const FormatBuffer &); // prevent copies

  66 
  67  protected:
  68   char _buffer[bufsz];
  69   inline FormatBuffer();
  70   inline void appendv(const char* format, va_list ap)  ATTRIBUTE_PRINTF(2, 0);
  71 };
  72 
  73 // Use malloc'ed buffer if static buffer is not enough.
  74 template <size_t bufsz = FormatBufferBase::BufferSize>
  75 class FormatBufferEx : public FormatBuffer<bufsz> {
  76  public:
  77   inline FormatBufferEx();
  78   ~FormatBufferEx(){
  79     if (_dyn_buffer != NULL) {
  80       ::free(_dyn_buffer);
  81     }
  82   }
  83   inline void append(const char* format, ...)  ATTRIBUTE_PRINTF(2, 3);
  84   inline void print(const char* format, ...)  ATTRIBUTE_PRINTF(2, 3);
  85   inline void printv(const char* format, va_list argp) ATTRIBUTE_PRINTF(2, 0);
  86 
  87   int size() { return _buffer_size; }
  88 
  89  private:
  90   inline void prepare_buffer(bool is_append, const char* format, va_list argp);
  91   char *_dyn_buffer;
  92   size_t _buffer_size;
  93 };
  94 
  95 template <size_t bufsz>
  96 FormatBuffer<bufsz>::FormatBuffer(const char * format, ...) : FormatBufferBase(_buffer) {
  97   va_list argp;
  98   va_start(argp, format);
  99   jio_vsnprintf(_buf, bufsz, format, argp);
 100   va_end(argp);
 101 }
 102 
 103 template <size_t bufsz>
 104 FormatBuffer<bufsz>::FormatBuffer(FormatBufferDummy dummy, const char * format, va_list ap) : FormatBufferBase(_buffer) {
 105   jio_vsnprintf(_buf, bufsz, format, ap);
 106 }
 107 
 108 template <size_t bufsz>
 109 FormatBuffer<bufsz>::FormatBuffer() : FormatBufferBase(_buffer) {
 110   _buf[0] = '\0';
 111 }
 112 
 113 template <size_t bufsz>
 114 void FormatBuffer<bufsz>::print(const char * format, ...) {
 115   va_list argp;
 116   va_start(argp, format);
 117   jio_vsnprintf(_buf, bufsz, format, argp);
 118   va_end(argp);
 119 }
 120 
 121 template <size_t bufsz>
 122 void FormatBuffer<bufsz>::printv(const char * format, va_list argp) {
 123   jio_vsnprintf(_buf, bufsz, format, argp);
 124 }
 125 
 126 template <size_t bufsz>
 127 void FormatBuffer<bufsz>::append(const char* format, ...) {
 128   va_list argp;
 129   va_start(argp, format);
 130   appendv(format, argp);
 131   va_end(argp);
 132 }
 133 
 134 template <size_t bufsz>
 135 void FormatBuffer<bufsz>::appendv(const char* format, va_list argp) {
 136   // Given that the constructor does a vsnprintf we can assume that
 137   // _buf is already initialized.
 138   size_t len = strlen(_buf);
 139   char* buf_end = _buf + len;
 140 
 141   jio_vsnprintf(buf_end, bufsz - len, format, argp);
 142 }
 143 
 144 template <size_t bufsz>
 145 FormatBufferEx<bufsz>::FormatBufferEx() : FormatBuffer<bufsz>(), _dyn_buffer(NULL), _buffer_size(bufsz) {
 146   // Do nothing.
 147 }
 148 
 149 template <size_t bufsz>
 150 void FormatBufferEx<bufsz>::print(const char * format, ...) {
 151   va_list argp;
 152   va_start(argp, format);
 153   printv(format, argp);
 154   va_end(argp);
 155 }
 156 
 157 template <size_t bufsz>
 158 void FormatBufferEx<bufsz>::prepare_buffer(bool is_append, const char * format, va_list argp) {
 159   size_t len = jio_vsnprintf(NULL, 0, format, argp) + 1;
 160   if (is_append) {
 161     len += strlen(FormatBufferBase::_buf);
 162   }
 163   if (len > _buffer_size) {
 164     _dyn_buffer = (_dyn_buffer == NULL) ? (char *)::malloc(len)
 165                                         : (char *)::realloc(_dyn_buffer, len);
 166     FormatBufferBase::_buf = _dyn_buffer;
 167     _buffer_size = len;
 168   }
 169 }
 170 
 171 template <size_t bufsz>
 172 void FormatBufferEx<bufsz>::printv(const char * format, va_list argp) {
 173   va_list argp_local;
 174   va_copy(argp_local, argp);
 175   prepare_buffer(false, format, argp_local);
 176   va_end(argp_local);
 177 
 178   jio_vsnprintf(FormatBufferBase::_buf, _buffer_size, format, argp);
 179 }
 180 
 181 template <size_t bufsz>
 182 void FormatBufferEx<bufsz>::append(const char* format, ...) {
 183   va_list argp, argp_prepare;
 184   va_start(argp, format);
 185   va_copy(argp_prepare, argp);
 186   prepare_buffer(true, format, argp_prepare);
 187   va_end(argp_prepare);
 188 
 189   FormatBuffer<bufsz>::appendv(format, argp);
 190   va_end(argp);
 191 }
 192 
 193 // Used to format messages.
 194 typedef FormatBuffer<> err_msg;
 195 
 196 #endif // SHARE_VM_UTILITIES_FORMATBUFFER_HPP
--- EOF ---