src/backend/utils/misc/ps_status.c

   1 /*--------------------------------------------------------------------
   2  * ps_status.c
   3  *
   4  * Routines to support changing the ps display of PostgreSQL backends
   5  * to contain some useful information. Mechanism differs wildly across
   6  * platforms.
   7  *
   8  * $PostgreSQL$
   9  *
  10  * Copyright (c) 2000-2008, PostgreSQL Global Development Group
  11  * various details abducted from various places
  12  *--------------------------------------------------------------------
  13  */
  14
  15 #include "postgres.h"
  16
  17 #include <unistd.h>
  18 #ifdef HAVE_SYS_PSTAT_H
  19 #include <sys/pstat.h>                  /* for HP-UX */
  20 #endif
  21 #ifdef HAVE_PS_STRINGS
  22 #include <machine/vmparam.h>    /* for old BSD */
  23 #include <sys/exec.h>
  24 #endif
  25 #if defined(__darwin__)
  26 #include <crt_externs.h>
  27 #endif
  28
  29 #include "libpq/libpq.h"
  30 #include "miscadmin.h"
  31 #include "utils/ps_status.h"
  32
  33 extern char **environ;
  34 bool            update_process_title = true;
  35
  36
  37 /*
  38  * Alternative ways of updating ps display:
  39  *
  40  * PS_USE_SETPROCTITLE
  41  *         use the function setproctitle(const char *, ...)
  42  *         (newer BSD systems)
  43  * PS_USE_PSTAT
  44  *         use the pstat(PSTAT_SETCMD, )
  45  *         (HPUX)
  46  * PS_USE_PS_STRINGS
  47  *         assign PS_STRINGS->ps_argvstr = "string"
  48  *         (some BSD systems)
  49  * PS_USE_CHANGE_ARGV
  50  *         assign argv[0] = "string"
  51  *         (some other BSD systems)
  52  * PS_USE_CLOBBER_ARGV
  53  *         write over the argv and environment area
  54  *         (most SysV-like systems)
  55  * PS_USE_WIN32
  56  *         push the string out as the name of a Windows event
  57  * PS_USE_NONE
  58  *         don't update ps display
  59  *         (This is the default, as it is safest.)
  60  */
  61 #if defined(HAVE_SETPROCTITLE)
  62 #define PS_USE_SETPROCTITLE
  63 #elif defined(HAVE_PSTAT) && defined(PSTAT_SETCMD)
  64 #define PS_USE_PSTAT
  65 #elif defined(HAVE_PS_STRINGS)
  66 #define PS_USE_PS_STRINGS
  67 #elif (defined(BSD) || defined(__bsdi__) || defined(__hurd__)) && !defined(__darwin__)
  68 #define PS_USE_CHANGE_ARGV
  69 #elif defined(__linux__) || defined(_AIX) || defined(__sgi) || (defined(sun) && !defined(BSD)) || defined(ultrix) || defined(__ksr__) || defined(__osf__) || defined(__svr4__) || defined(__svr5__) || defined(__darwin__)
  70 #define PS_USE_CLOBBER_ARGV
  71 #elif defined(WIN32)
  72 #define PS_USE_WIN32
  73 #else
  74 #define PS_USE_NONE
  75 #endif
  76
  77
  78 /* Different systems want the buffer padded differently */
  79 #if defined(_AIX) || defined(__linux__) || defined(__svr4__)
  80 #define PS_PADDING '\0'
  81 #else
  82 #define PS_PADDING ' '
  83 #endif
  84
  85
  86 #ifndef PS_USE_CLOBBER_ARGV
  87 /* all but one options need a buffer to write their ps line in */
  88 #define PS_BUFFER_SIZE 256
  89 static char ps_buffer[PS_BUFFER_SIZE];
  90 static const size_t ps_buffer_size = PS_BUFFER_SIZE;
  91 #else                                                   /* PS_USE_CLOBBER_ARGV */
  92 static char *ps_buffer;                 /* will point to argv area */
  93 static size_t ps_buffer_size;   /* space determined at run time */
  94 static size_t last_status_len;  /* use to minimize length of clobber */
  95 #endif   /* PS_USE_CLOBBER_ARGV */
  96
  97 static size_t ps_buffer_fixed_size;             /* size of the constant prefix */
  98
  99 /* save the original argv[] location here */
 100 static int      save_argc;
 101 static char **save_argv;
 102
 103
 104 /*
 105  * Call this early in startup to save the original argc/argv values.
 106  * If needed, we make a copy of the original argv[] array to preserve it
 107  * from being clobbered by subsequent ps_display actions.
 108  *
 109  * (The original argv[] will not be overwritten by this routine, but may be
 110  * overwritten during init_ps_display.  Also, the physical location of the
 111  * environment strings may be moved, so this should be called before any code
 112  * that might try to hang onto a getenv() result.)
 113  */
 114 char      **
 115 save_ps_display_args(int argc, char **argv)
 116 {
 117         save_argc = argc;
 118         save_argv = argv;
 119
 120 #if defined(PS_USE_CLOBBER_ARGV)
 121
 122         /*
 123          * If we're going to overwrite the argv area, count the available space.
 124          * Also move the environment to make additional room.
 125          */
 126         {
 127                 char       *end_of_area = NULL;
 128                 char      **new_environ;
 129                 int                     i;
 130
 131                 /*
 132                  * check for contiguous argv strings
 133                  */
 134                 for (i = 0; i < argc; i++)
 135                 {
 136                         if (i == 0 || end_of_area + 1 == argv[i])
 137                                 end_of_area = argv[i] + strlen(argv[i]);
 138                 }
 139
 140                 if (end_of_area == NULL)        /* probably can't happen? */
 141                 {
 142                         ps_buffer = NULL;
 143                         ps_buffer_size = 0;
 144                         return argv;
 145                 }
 146
 147                 /*
 148                  * check for contiguous environ strings following argv
 149                  */
 150                 for (i = 0; environ[i] != NULL; i++)
 151                 {
 152                         if (end_of_area + 1 == environ[i])
 153                                 end_of_area = environ[i] + strlen(environ[i]);
 154                 }
 155
 156                 ps_buffer = argv[0];
 157                 last_status_len = ps_buffer_size = end_of_area - argv[0];
 158
 159                 /*
 160                  * move the environment out of the way
 161                  */
 162                 new_environ = (char **) malloc((i + 1) * sizeof(char *));
 163                 for (i = 0; environ[i] != NULL; i++)
 164                         new_environ[i] = strdup(environ[i]);
 165                 new_environ[i] = NULL;
 166                 environ = new_environ;
 167         }
 168 #endif   /* PS_USE_CLOBBER_ARGV */
 169
 170 #if defined(PS_USE_CHANGE_ARGV) || defined(PS_USE_CLOBBER_ARGV)
 171
 172         /*
 173          * If we're going to change the original argv[] then make a copy for
 174          * argument parsing purposes.
 175          *
 176          * (NB: do NOT think to remove the copying of argv[], even though
 177          * postmaster.c finishes looking at argv[] long before we ever consider
 178          * changing the ps display.  On some platforms, getopt() keeps pointers
 179          * into the argv array, and will get horribly confused when it is
 180          * re-called to analyze a subprocess' argument string if the argv storage
 181          * has been clobbered meanwhile.  Other platforms have other dependencies
 182          * on argv[].
 183          */
 184         {
 185                 char      **new_argv;
 186                 int                     i;
 187
 188                 new_argv = (char **) malloc((argc + 1) * sizeof(char *));
 189                 for (i = 0; i < argc; i++)
 190                         new_argv[i] = strdup(argv[i]);
 191                 new_argv[argc] = NULL;
 192
 193 #if defined(__darwin__)
 194
 195                 /*
 196                  * Darwin (and perhaps other NeXT-derived platforms?) has a static
 197                  * copy of the argv pointer, which we may fix like so:
 198                  */
 199                 *_NSGetArgv() = new_argv;
 200 #endif
 201
 202                 argv = new_argv;
 203         }
 204 #endif   /* PS_USE_CHANGE_ARGV or PS_USE_CLOBBER_ARGV */
 205
 206         return argv;
 207 }
 208
 209 /*
 210  * Call this once during subprocess startup to set the identification
 211  * values.      At this point, the original argv[] array may be overwritten.
 212  */
 213 void
 214 init_ps_display(const char *username, const char *dbname,
 215                                 const char *host_info, const char *initial_str)
 216 {
 217         Assert(username);
 218         Assert(dbname);
 219         Assert(host_info);
 220
 221 #ifndef PS_USE_NONE
 222         /* no ps display for stand-alone backend */
 223         if (!IsUnderPostmaster)
 224                 return;
 225
 226         /* no ps display if you didn't call save_ps_display_args() */
 227         if (!save_argv)
 228                 return;
 229 #ifdef PS_USE_CLOBBER_ARGV
 230         /* If ps_buffer is a pointer, it might still be null */
 231         if (!ps_buffer)
 232                 return;
 233 #endif
 234
 235         /*
 236          * Overwrite argv[] to point at appropriate space, if needed
 237          */
 238
 239 #ifdef PS_USE_CHANGE_ARGV
 240         save_argv[0] = ps_buffer;
 241         save_argv[1] = NULL;
 242 #endif   /* PS_USE_CHANGE_ARGV */
 243
 244 #ifdef PS_USE_CLOBBER_ARGV
 245         {
 246                 int                     i;
 247
 248                 /* make extra argv slots point at end_of_area (a NUL) */
 249                 for (i = 1; i < save_argc; i++)
 250                         save_argv[i] = ps_buffer + ps_buffer_size;
 251         }
 252 #endif   /* PS_USE_CLOBBER_ARGV */
 253
 254         /*
 255          * Make fixed prefix of ps display.
 256          */
 257
 258 #ifdef PS_USE_SETPROCTITLE
 259
 260         /*
 261          * apparently setproctitle() already adds a `progname:' prefix to the ps
 262          * line
 263          */
 264         snprintf(ps_buffer, ps_buffer_size,
 265                          "%s %s %s ",
 266                          username, dbname, host_info);
 267 #else
 268         snprintf(ps_buffer, ps_buffer_size,
 269                          "postgres: %s %s %s ",
 270                          username, dbname, host_info);
 271 #endif
 272
 273         ps_buffer_fixed_size = strlen(ps_buffer);
 274
 275         set_ps_display(initial_str, true);
 276 #endif   /* not PS_USE_NONE */
 277 }
 278
 279
 280
 281 /*
 282  * Call this to update the ps status display to a fixed prefix plus an
 283  * indication of what you're currently doing passed in the argument.
 284  */
 285 void
 286 set_ps_display(const char *activity, bool force)
 287 {
 288
 289         if (!force && !update_process_title)
 290                 return;
 291
 292 #ifndef PS_USE_NONE
 293         /* no ps display for stand-alone backend */
 294         if (!IsUnderPostmaster)
 295                 return;
 296
 297 #ifdef PS_USE_CLOBBER_ARGV
 298         /* If ps_buffer is a pointer, it might still be null */
 299         if (!ps_buffer)
 300                 return;
 301 #endif
 302
 303         /* Update ps_buffer to contain both fixed part and activity */
 304         strlcpy(ps_buffer + ps_buffer_fixed_size, activity,
 305                         ps_buffer_size - ps_buffer_fixed_size);
 306
 307         /* Transmit new setting to kernel, if necessary */
 308
 309 #ifdef PS_USE_SETPROCTITLE
 310         setproctitle("%s", ps_buffer);
 311 #endif
 312
 313 #ifdef PS_USE_PSTAT
 314         {
 315                 union pstun pst;
 316
 317                 pst.pst_command = ps_buffer;
 318                 pstat(PSTAT_SETCMD, pst, strlen(ps_buffer), 0, 0);
 319         }
 320 #endif   /* PS_USE_PSTAT */
 321
 322 #ifdef PS_USE_PS_STRINGS
 323         PS_STRINGS->ps_nargvstr = 1;
 324         PS_STRINGS->ps_argvstr = ps_buffer;
 325 #endif   /* PS_USE_PS_STRINGS */
 326
 327 #ifdef PS_USE_CLOBBER_ARGV
 328         {
 329                 int                     buflen;
 330
 331                 /* pad unused memory */
 332                 buflen = strlen(ps_buffer);
 333                 /* clobber remainder of old status string */
 334                 if (last_status_len > buflen)
 335                         MemSet(ps_buffer + buflen, PS_PADDING, last_status_len - buflen);
 336                 last_status_len = buflen;
 337         }
 338 #endif   /* PS_USE_CLOBBER_ARGV */
 339
 340 #ifdef PS_USE_WIN32
 341         {
 342                 /*
 343                  * Win32 does not support showing any changed arguments. To make it at
 344                  * all possible to track which backend is doing what, we create a
 345                  * named object that can be viewed with for example Process Explorer.
 346                  */
 347                 static HANDLE ident_handle = INVALID_HANDLE_VALUE;
 348                 char            name[PS_BUFFER_SIZE + 32];
 349
 350                 if (ident_handle != INVALID_HANDLE_VALUE)
 351                         CloseHandle(ident_handle);
 352
 353                 sprintf(name, "pgident(%d): %s", MyProcPid, ps_buffer);
 354
 355                 ident_handle = CreateEvent(NULL, TRUE, FALSE, name);
 356         }
 357 #endif   /* PS_USE_WIN32 */
 358 #endif   /* not PS_USE_NONE */
 359 }
 360
 361
 362 /*
 363  * Returns what's currently in the ps display, in case someone needs
 364  * it.  Note that only the activity part is returned.  On some platforms
 365  * the string will not be null-terminated, so return the effective
 366  * length into *displen.
 367  */
 368 const char *
 369 get_ps_display(int *displen)
 370 {
 371 #ifdef PS_USE_CLOBBER_ARGV
 372         size_t          offset;
 373
 374         /* If ps_buffer is a pointer, it might still be null */
 375         if (!ps_buffer)
 376         {
 377                 *displen = 0;
 378                 return "";
 379         }
 380
 381         /* Remove any trailing spaces to offset the effect of PS_PADDING */
 382         offset = ps_buffer_size;
 383         while (offset > ps_buffer_fixed_size && ps_buffer[offset - 1] == PS_PADDING)
 384                 offset--;
 385
 386         *displen = offset - ps_buffer_fixed_size;
 387 #else
 388         *displen = strlen(ps_buffer + ps_buffer_fixed_size);
 389 #endif
 390
 391         return ps_buffer + ps_buffer_fixed_size;
 392 }