1 /*
   2  * Copyright (c) 1997, 2014, 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_RUNTIME_ARGUMENTS_HPP
  26 #define SHARE_VM_RUNTIME_ARGUMENTS_HPP
  27 
  28 #include "runtime/java.hpp"
  29 #include "runtime/perfData.hpp"
  30 #include "utilities/debug.hpp"
  31 #include "utilities/top.hpp"
  32 
  33 // Arguments parses the command line and recognizes options
  34 
  35 // Invocation API hook typedefs (these should really be defined in jni.hpp)
  36 extern "C" {
  37   typedef void (JNICALL *abort_hook_t)(void);
  38   typedef void (JNICALL *exit_hook_t)(jint code);
  39   typedef jint (JNICALL *vfprintf_hook_t)(FILE *fp, const char *format, va_list args)  ATTRIBUTE_PRINTF(2, 0);
  40 }
  41 
  42 // Forward declarations
  43 
  44 class SysClassPath;
  45 
  46 // Element describing System and User (-Dkey=value flags) defined property.
  47 
  48 class SystemProperty: public CHeapObj<mtInternal> {
  49  private:
  50   char*           _key;
  51   char*           _value;
  52   SystemProperty* _next;
  53   bool            _writeable;
  54   bool writeable()   { return _writeable; }
  55 
  56  public:
  57   // Accessors
  58   const char* key() const                   { return _key; }
  59   char* value() const                       { return _value; }
  60   SystemProperty* next() const              { return _next; }
  61   void set_next(SystemProperty* next)       { _next = next; }
  62   bool set_value(char *value) {
  63     if (writeable()) {
  64       if (_value != NULL) {
  65         FreeHeap(_value);
  66       }
  67       _value = AllocateHeap(strlen(value)+1, mtInternal);
  68       if (_value != NULL) {
  69         strcpy(_value, value);
  70       }
  71       return true;
  72     }
  73     return false;
  74   }
  75 
  76   void append_value(const char *value) {
  77     char *sp;
  78     size_t len = 0;
  79     if (value != NULL) {
  80       len = strlen(value);
  81       if (_value != NULL) {
  82         len += strlen(_value);
  83       }
  84       sp = AllocateHeap(len+2, mtInternal);
  85       if (sp != NULL) {
  86         if (_value != NULL) {
  87           strcpy(sp, _value);
  88           strcat(sp, os::path_separator());
  89           strcat(sp, value);
  90           FreeHeap(_value);
  91         } else {
  92           strcpy(sp, value);
  93         }
  94         _value = sp;
  95       }
  96     }
  97   }
  98 
  99   // Constructor
 100   SystemProperty(const char* key, const char* value, bool writeable) {
 101     if (key == NULL) {
 102       _key = NULL;
 103     } else {
 104       _key = AllocateHeap(strlen(key)+1, mtInternal);
 105       strcpy(_key, key);
 106     }
 107     if (value == NULL) {
 108       _value = NULL;
 109     } else {
 110       _value = AllocateHeap(strlen(value)+1, mtInternal);
 111       strcpy(_value, value);
 112     }
 113     _next = NULL;
 114     _writeable = writeable;
 115   }
 116 };
 117 
 118 
 119 // For use by -agentlib, -agentpath and -Xrun
 120 class AgentLibrary : public CHeapObj<mtInternal> {
 121   friend class AgentLibraryList;
 122 public:
 123   // Is this library valid or not. Don't rely on os_lib == NULL as statically
 124   // linked lib could have handle of RTLD_DEFAULT which == 0 on some platforms
 125   enum AgentState {
 126     agent_invalid = 0,
 127     agent_valid   = 1
 128   };
 129 
 130  private:
 131   char*           _name;
 132   char*           _options;
 133   void*           _os_lib;
 134   bool            _is_absolute_path;
 135   bool            _is_static_lib;
 136   AgentState      _state;
 137   AgentLibrary*   _next;
 138 
 139  public:
 140   // Accessors
 141   const char* name() const                  { return _name; }
 142   char* options() const                     { return _options; }
 143   bool is_absolute_path() const             { return _is_absolute_path; }
 144   void* os_lib() const                      { return _os_lib; }
 145   void set_os_lib(void* os_lib)             { _os_lib = os_lib; }
 146   AgentLibrary* next() const                { return _next; }
 147   bool is_static_lib() const                { return _is_static_lib; }
 148   void set_static_lib(bool is_static_lib)   { _is_static_lib = is_static_lib; }
 149   bool valid()                              { return (_state == agent_valid); }
 150   void set_valid()                          { _state = agent_valid; }
 151   void set_invalid()                        { _state = agent_invalid; }
 152 
 153   // Constructor
 154   AgentLibrary(const char* name, const char* options, bool is_absolute_path, void* os_lib) {
 155     _name = AllocateHeap(strlen(name)+1, mtInternal);
 156     strcpy(_name, name);
 157     if (options == NULL) {
 158       _options = NULL;
 159     } else {
 160       _options = AllocateHeap(strlen(options)+1, mtInternal);
 161       strcpy(_options, options);
 162     }
 163     _is_absolute_path = is_absolute_path;
 164     _os_lib = os_lib;
 165     _next = NULL;
 166     _state = agent_invalid;
 167     _is_static_lib = false;
 168   }
 169 };
 170 
 171 // maintain an order of entry list of AgentLibrary
 172 class AgentLibraryList VALUE_OBJ_CLASS_SPEC {
 173  private:
 174   AgentLibrary*   _first;
 175   AgentLibrary*   _last;
 176  public:
 177   bool is_empty() const                     { return _first == NULL; }
 178   AgentLibrary* first() const               { return _first; }
 179 
 180   // add to the end of the list
 181   void add(AgentLibrary* lib) {
 182     if (is_empty()) {
 183       _first = _last = lib;
 184     } else {
 185       _last->_next = lib;
 186       _last = lib;
 187     }
 188     lib->_next = NULL;
 189   }
 190 
 191   // search for and remove a library known to be in the list
 192   void remove(AgentLibrary* lib) {
 193     AgentLibrary* curr;
 194     AgentLibrary* prev = NULL;
 195     for (curr = first(); curr != NULL; prev = curr, curr = curr->next()) {
 196       if (curr == lib) {
 197         break;
 198       }
 199     }
 200     assert(curr != NULL, "always should be found");
 201 
 202     if (curr != NULL) {
 203       // it was found, by-pass this library
 204       if (prev == NULL) {
 205         _first = curr->_next;
 206       } else {
 207         prev->_next = curr->_next;
 208       }
 209       if (curr == _last) {
 210         _last = prev;
 211       }
 212       curr->_next = NULL;
 213     }
 214   }
 215 
 216   AgentLibraryList() {
 217     _first = NULL;
 218     _last = NULL;
 219   }
 220 };
 221 
 222 
 223 class Arguments : AllStatic {
 224   friend class VMStructs;
 225   friend class JvmtiExport;
 226  public:
 227   // Operation modi
 228   enum Mode {
 229     _int,       // corresponds to -Xint
 230     _mixed,     // corresponds to -Xmixed
 231     _comp       // corresponds to -Xcomp
 232   };
 233 
 234   enum ArgsRange {
 235     arg_unreadable = -3,
 236     arg_too_small  = -2,
 237     arg_too_big    = -1,
 238     arg_in_range   = 0
 239   };
 240 
 241  private:
 242 
 243   // an array containing all flags specified in the .hotspotrc file
 244   static char** _jvm_flags_array;
 245   static int    _num_jvm_flags;
 246   // an array containing all jvm arguments specified in the command line
 247   static char** _jvm_args_array;
 248   static int    _num_jvm_args;
 249   // string containing all java command (class/jarfile name and app args)
 250   static char* _java_command;
 251 
 252   // Property list
 253   static SystemProperty* _system_properties;
 254 
 255   // Quick accessor to System properties in the list:
 256   static SystemProperty *_java_ext_dirs;
 257   static SystemProperty *_java_endorsed_dirs;
 258   static SystemProperty *_sun_boot_library_path;
 259   static SystemProperty *_java_library_path;
 260   static SystemProperty *_java_home;
 261   static SystemProperty *_java_class_path;
 262   static SystemProperty *_sun_boot_class_path;
 263 
 264   // Meta-index for knowing what packages are in the boot class path
 265   static char* _meta_index_path;
 266   static char* _meta_index_dir;
 267 
 268   // java.vendor.url.bug, bug reporting URL for fatal errors.
 269   static const char* _java_vendor_url_bug;
 270 
 271   // sun.java.launcher, private property to provide information about
 272   // java/gamma launcher
 273   static const char* _sun_java_launcher;
 274 
 275   // sun.java.launcher.pid, private property
 276   static int    _sun_java_launcher_pid;
 277 
 278   // was this VM created by the gamma launcher
 279   static bool   _created_by_gamma_launcher;
 280 
 281   // Option flags
 282   static bool   _has_profile;
 283   static const char*  _gc_log_filename;
 284   // Value of the conservative maximum heap alignment needed
 285   static size_t  _conservative_max_heap_alignment;
 286 
 287   static uintx  _min_heap_size;
 288 
 289   // -Xrun arguments
 290   static AgentLibraryList _libraryList;
 291   static void add_init_library(const char* name, char* options)
 292     { _libraryList.add(new AgentLibrary(name, options, false, NULL)); }
 293 
 294   // -agentlib and -agentpath arguments
 295   static AgentLibraryList _agentList;
 296   static void add_init_agent(const char* name, char* options, bool absolute_path)
 297     { _agentList.add(new AgentLibrary(name, options, absolute_path, NULL)); }
 298 
 299   // Late-binding agents not started via arguments
 300   static void add_loaded_agent(AgentLibrary *agentLib)
 301     { _agentList.add(agentLib); }
 302   static void add_loaded_agent(const char* name, char* options, bool absolute_path, void* os_lib)
 303     { _agentList.add(new AgentLibrary(name, options, absolute_path, os_lib)); }
 304 
 305   // Operation modi
 306   static Mode _mode;
 307   static void set_mode_flags(Mode mode);
 308   static bool _java_compiler;
 309   static void set_java_compiler(bool arg) { _java_compiler = arg; }
 310   static bool java_compiler()   { return _java_compiler; }
 311 
 312   // -Xdebug flag
 313   static bool _xdebug_mode;
 314   static void set_xdebug_mode(bool arg) { _xdebug_mode = arg; }
 315   static bool xdebug_mode()             { return _xdebug_mode; }
 316 
 317   // Used to save default settings
 318   static bool _AlwaysCompileLoopMethods;
 319   static bool _UseOnStackReplacement;
 320   static bool _BackgroundCompilation;
 321   static bool _ClipInlining;
 322   static bool _CIDynamicCompilePriority;
 323 
 324   // Tiered
 325   static void set_tiered_flags();
 326   // CMS/ParNew garbage collectors
 327   static void set_parnew_gc_flags();
 328   static void set_cms_and_parnew_gc_flags();
 329   // UseParallel[Old]GC
 330   static void set_parallel_gc_flags();
 331   // Garbage-First (UseG1GC)
 332   static void set_g1_gc_flags();
 333   // GC ergonomics
 334   static void set_conservative_max_heap_alignment();
 335   static void set_use_compressed_oops();
 336   static void set_use_compressed_klass_ptrs();
 337   static void set_ergonomics_flags();
 338   static void set_shared_spaces_flags();
 339   // limits the given memory size by the maximum amount of memory this process is
 340   // currently allowed to allocate or reserve.
 341   static julong limit_by_allocatable_memory(julong size);
 342   // Setup heap size
 343   static void set_heap_size();
 344   // Based on automatic selection criteria, should the
 345   // low pause collector be used.
 346   static bool should_auto_select_low_pause_collector();
 347 
 348   // Bytecode rewriting
 349   static void set_bytecode_flags();
 350 
 351   // Invocation API hooks
 352   static abort_hook_t     _abort_hook;
 353   static exit_hook_t      _exit_hook;
 354   static vfprintf_hook_t  _vfprintf_hook;
 355 
 356   // System properties
 357   static bool add_property(const char* prop);
 358 
 359   // Aggressive optimization flags.
 360   static void set_aggressive_opts_flags();
 361 
 362   // Argument parsing
 363   static void do_pd_flag_adjustments();
 364   static bool parse_argument(const char* arg, Flag::Flags origin);
 365   static bool process_argument(const char* arg, jboolean ignore_unrecognized, Flag::Flags origin);
 366   static void process_java_launcher_argument(const char*, void*);
 367   static void process_java_compiler_argument(char* arg);
 368   static jint parse_options_environment_variable(const char* name, SysClassPath* scp_p, bool* scp_assembly_required_p);
 369   static jint parse_java_tool_options_environment_variable(SysClassPath* scp_p, bool* scp_assembly_required_p);
 370   static jint parse_java_options_environment_variable(SysClassPath* scp_p, bool* scp_assembly_required_p);
 371   static jint parse_vm_init_args(const JavaVMInitArgs* args);
 372   static jint parse_each_vm_init_arg(const JavaVMInitArgs* args, SysClassPath* scp_p, bool* scp_assembly_required_p, Flag::Flags origin);
 373   static jint finalize_vm_init_args(SysClassPath* scp_p, bool scp_assembly_required);
 374   static bool is_bad_option(const JavaVMOption* option, jboolean ignore, const char* option_type);
 375 
 376   static bool is_bad_option(const JavaVMOption* option, jboolean ignore) {
 377     return is_bad_option(option, ignore, NULL);
 378   }
 379 
 380   static bool is_percentage(uintx val) {
 381     return val <= 100;
 382   }
 383 
 384   static bool verify_interval(uintx val, uintx min,
 385                               uintx max, const char* name);
 386   static bool verify_min_value(intx val, intx min, const char* name);
 387   static bool verify_percentage(uintx value, const char* name);
 388   static void describe_range_error(ArgsRange errcode);
 389   static ArgsRange check_memory_size(julong size, julong min_size);
 390   static ArgsRange parse_memory_size(const char* s, julong* long_arg,
 391                                      julong min_size);
 392   // Parse a string for a unsigned integer.  Returns true if value
 393   // is an unsigned integer greater than or equal to the minimum
 394   // parameter passed and returns the value in uintx_arg.  Returns
 395   // false otherwise, with uintx_arg undefined.
 396   static bool parse_uintx(const char* value, uintx* uintx_arg,
 397                           uintx min_size);
 398 
 399   // methods to build strings from individual args
 400   static void build_jvm_args(const char* arg);
 401   static void build_jvm_flags(const char* arg);
 402   static void add_string(char*** bldarray, int* count, const char* arg);
 403   static const char* build_resource_string(char** args, int count);
 404 
 405   static bool methodExists(
 406     char* className, char* methodName,
 407     int classesNum, char** classes, bool* allMethods,
 408     int methodsNum, char** methods, bool* allClasses
 409   );
 410 
 411   static void parseOnlyLine(
 412     const char* line,
 413     short* classesNum, short* classesMax, char*** classes, bool** allMethods,
 414     short* methodsNum, short* methodsMax, char*** methods, bool** allClasses
 415   );
 416 
 417   // Returns true if the string s is in the list of flags that have recently
 418   // been made obsolete.  If we detect one of these flags on the command
 419   // line, instead of failing we print a warning message and ignore the
 420   // flag.  This gives the user a release or so to stop using the flag.
 421   static bool is_newly_obsolete(const char* s, JDK_Version* buffer);
 422 
 423   static short  CompileOnlyClassesNum;
 424   static short  CompileOnlyClassesMax;
 425   static char** CompileOnlyClasses;
 426   static bool*  CompileOnlyAllMethods;
 427 
 428   static short  CompileOnlyMethodsNum;
 429   static short  CompileOnlyMethodsMax;
 430   static char** CompileOnlyMethods;
 431   static bool*  CompileOnlyAllClasses;
 432 
 433   static short  InterpretOnlyClassesNum;
 434   static short  InterpretOnlyClassesMax;
 435   static char** InterpretOnlyClasses;
 436   static bool*  InterpretOnlyAllMethods;
 437 
 438   static bool   CheckCompileOnly;
 439 
 440   static char*  SharedArchivePath;
 441 
 442  public:
 443   // Parses the arguments, first phase
 444   static jint parse(const JavaVMInitArgs* args);
 445   // Apply ergonomics
 446   static jint apply_ergo();
 447   // Adjusts the arguments after the OS have adjusted the arguments
 448   static jint adjust_after_os();
 449 
 450   // Verifies that the given value will fit as a MinHeapFreeRatio. If not, an error
 451   // message is returned in the provided buffer.
 452   static bool verify_MinHeapFreeRatio(FormatBuffer<80>& err_msg, uintx min_heap_free_ratio);
 453 
 454   // Verifies that the given value will fit as a MaxHeapFreeRatio. If not, an error
 455   // message is returned in the provided buffer.
 456   static bool verify_MaxHeapFreeRatio(FormatBuffer<80>& err_msg, uintx max_heap_free_ratio);
 457 
 458   // Check for consistency in the selection of the garbage collector.
 459   static bool check_gc_consistency();
 460   static void check_deprecated_gcs();
 461   static void check_deprecated_gc_flags();
 462   // Check consistecy or otherwise of VM argument settings
 463   static bool check_vm_args_consistency();
 464   // Check stack pages settings
 465   static bool check_stack_pages();
 466   // Used by os_solaris
 467   static bool process_settings_file(const char* file_name, bool should_exist, jboolean ignore_unrecognized);
 468 
 469   static size_t conservative_max_heap_alignment() { return _conservative_max_heap_alignment; }
 470   // Return the maximum size a heap with compressed oops can take
 471   static size_t max_heap_for_compressed_oops();
 472 
 473   // return a char* array containing all options
 474   static char** jvm_flags_array()          { return _jvm_flags_array; }
 475   static char** jvm_args_array()           { return _jvm_args_array; }
 476   static int num_jvm_flags()               { return _num_jvm_flags; }
 477   static int num_jvm_args()                { return _num_jvm_args; }
 478   // return the arguments passed to the Java application
 479   static const char* java_command()        { return _java_command; }
 480 
 481   // print jvm_flags, jvm_args and java_command
 482   static void print_on(outputStream* st);
 483 
 484   // convenient methods to obtain / print jvm_flags and jvm_args
 485   static const char* jvm_flags()           { return build_resource_string(_jvm_flags_array, _num_jvm_flags); }
 486   static const char* jvm_args()            { return build_resource_string(_jvm_args_array, _num_jvm_args); }
 487   static void print_jvm_flags_on(outputStream* st);
 488   static void print_jvm_args_on(outputStream* st);
 489 
 490   // -Dkey=value flags
 491   static SystemProperty*  system_properties()   { return _system_properties; }
 492   static const char*    get_property(const char* key);
 493 
 494   // -Djava.vendor.url.bug
 495   static const char* java_vendor_url_bug()  { return _java_vendor_url_bug; }
 496 
 497   // -Dsun.java.launcher
 498   static const char* sun_java_launcher()    { return _sun_java_launcher; }
 499   // Was VM created by a Java launcher?
 500   static bool created_by_java_launcher();
 501   // Was VM created by the gamma Java launcher?
 502   static bool created_by_gamma_launcher();
 503   // -Dsun.java.launcher.pid
 504   static int sun_java_launcher_pid()        { return _sun_java_launcher_pid; }
 505 
 506   // -Xloggc:<file>, if not specified will be NULL
 507   static const char* gc_log_filename()      { return _gc_log_filename; }
 508 
 509   // -Xprof
 510   static bool has_profile()                 { return _has_profile; }
 511 
 512   // -Xms, -Xmx
 513   static uintx min_heap_size()              { return _min_heap_size; }
 514   static void  set_min_heap_size(uintx v)   { _min_heap_size = v;  }
 515 
 516   // -Xrun
 517   static AgentLibrary* libraries()          { return _libraryList.first(); }
 518   static bool init_libraries_at_startup()   { return !_libraryList.is_empty(); }
 519   static void convert_library_to_agent(AgentLibrary* lib)
 520                                             { _libraryList.remove(lib);
 521                                               _agentList.add(lib); }
 522 
 523   // -agentlib -agentpath
 524   static AgentLibrary* agents()             { return _agentList.first(); }
 525   static bool init_agents_at_startup()      { return !_agentList.is_empty(); }
 526 
 527   // abort, exit, vfprintf hooks
 528   static abort_hook_t    abort_hook()       { return _abort_hook; }
 529   static exit_hook_t     exit_hook()        { return _exit_hook; }
 530   static vfprintf_hook_t vfprintf_hook()    { return _vfprintf_hook; }
 531 
 532   static bool GetCheckCompileOnly ()        { return CheckCompileOnly; }
 533 
 534   static const char* GetSharedArchivePath() { return SharedArchivePath; }
 535 
 536   static bool CompileMethod(char* className, char* methodName) {
 537     return
 538       methodExists(
 539         className, methodName,
 540         CompileOnlyClassesNum, CompileOnlyClasses, CompileOnlyAllMethods,
 541         CompileOnlyMethodsNum, CompileOnlyMethods, CompileOnlyAllClasses
 542       );
 543   }
 544 
 545   // Java launcher properties
 546   static void process_sun_java_launcher_properties(JavaVMInitArgs* args);
 547 
 548   // System properties
 549   static void init_system_properties();
 550 
 551   // Update/Initialize System properties after JDK version number is known
 552   static void init_version_specific_system_properties();
 553 
 554   // Property List manipulation
 555   static void PropertyList_add(SystemProperty** plist, SystemProperty *element);
 556   static void PropertyList_add(SystemProperty** plist, const char* k, char* v);
 557   static void PropertyList_unique_add(SystemProperty** plist, const char* k, char* v) {
 558     PropertyList_unique_add(plist, k, v, false);
 559   }
 560   static void PropertyList_unique_add(SystemProperty** plist, const char* k, char* v, jboolean append);
 561   static const char* PropertyList_get_value(SystemProperty* plist, const char* key);
 562   static int  PropertyList_count(SystemProperty* pl);
 563   static const char* PropertyList_get_key_at(SystemProperty* pl,int index);
 564   static char* PropertyList_get_value_at(SystemProperty* pl,int index);
 565 
 566   // Miscellaneous System property value getter and setters.
 567   static void set_dll_dir(char *value) { _sun_boot_library_path->set_value(value); }
 568   static void set_java_home(char *value) { _java_home->set_value(value); }
 569   static void set_library_path(char *value) { _java_library_path->set_value(value); }
 570   static void set_ext_dirs(char *value) { _java_ext_dirs->set_value(value); }
 571   static void set_endorsed_dirs(char *value) { _java_endorsed_dirs->set_value(value); }
 572   static void set_sysclasspath(char *value) { _sun_boot_class_path->set_value(value); }
 573   static void append_sysclasspath(const char *value) { _sun_boot_class_path->append_value(value); }
 574   static void set_meta_index_path(char* meta_index_path, char* meta_index_dir) {
 575     _meta_index_path = meta_index_path;
 576     _meta_index_dir  = meta_index_dir;
 577   }
 578 
 579   static char *get_java_home() { return _java_home->value(); }
 580   static char *get_dll_dir() { return _sun_boot_library_path->value(); }
 581   static char *get_endorsed_dir() { return _java_endorsed_dirs->value(); }
 582   static char *get_sysclasspath() { return _sun_boot_class_path->value(); }
 583   static char* get_meta_index_path() { return _meta_index_path; }
 584   static char* get_meta_index_dir()  { return _meta_index_dir;  }
 585 
 586   // Operation modi
 587   static Mode mode()                        { return _mode; }
 588 
 589   // Utility: copies src into buf, replacing "%%" with "%" and "%p" with pid.
 590   static bool copy_expand_pid(const char* src, size_t srclen, char* buf, size_t buflen);
 591 };
 592 
 593 #endif // SHARE_VM_RUNTIME_ARGUMENTS_HPP