granicus.if.org Git - postgresql/blob - 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. Differs wildly across
   6  * platforms.
   7  *
   8  * $Header: /cvsroot/pgsql/src/backend/utils/misc/ps_status.c,v 1.4 2001/03/22 04:00:06 momjian Exp $
   9  *
  10  * Copyright 2000 by PostgreSQL Global Development Group
  11  * various details abducted from various places
  12  *--------------------------------------------------------------------
  13  */
  14
  15 #include "postgres.h"
  16
  17 #include <unistd.h>
  18
  19
  20 #ifdef HAVE_SYS_PSTAT_H
  21 #include <sys/pstat.h>                  /* for HP-UX */
  22 #endif
  23 #ifdef HAVE_PS_STRINGS
  24 #include <machine/vmparam.h>    /* for old BSD */
  25 #include <sys/exec.h>
  26 #endif
  27
  28 #include "miscadmin.h"
  29
  30 #include "utils/ps_status.h"
  31
  32 extern char **environ;
  33
  34
  35 /*------
  36  * Alternative ways of updating ps display:
  37  *
  38  * PS_USE_SETPROCTITLE
  39  *         use the function setproctitle(const char *, ...)
  40  *         (newer BSD systems)
  41  * PS_USE_PSTAT
  42  *         use the pstat(PSTAT_SETCMD, )
  43  *         (HPUX)
  44  * PS_USE_PS_STRINGS
  45  *         assign PS_STRINGS->ps_argvstr = "string"
  46  *         (some BSD systems)
  47  * PS_USE_CHANGE_ARGV
  48  *         assign argv[0] = "string"
  49  *         (some other BSD systems)
  50  * PS_USE_CLOBBER_ARGV
  51  *         write over the argv and environment area
  52  *         (most SysV-like systems)
  53  * PS_USE_NONE
  54  *         don't update ps display
  55  *         (This is the default, as it is safest.)
  56  */
  57 #if defined(HAVE_SETPROCTITLE)
  58 #define PS_USE_SETPROCTITLE
  59 #elif defined(HAVE_PSTAT) && defined(PSTAT_SETCMD)
  60 #define PS_USE_PSTAT
  61 #elif defined(HAVE_PS_STRINGS)
  62 #define PS_USE_PS_STRINGS
  63 #elif defined(BSD) || defined(__bsdi__) || defined(__hurd__)
  64 #define PS_USE_CHANGE_ARGV
  65 #elif defined(__linux__) || defined(_AIX4) || defined(_AIX3) || defined(__sgi) || (defined(sun) && !defined(BSD)) || defined(ultrix) || defined(__ksr__) || defined(__osf__) || defined(__QNX__) || defined(__svr4__) || defined(__svr5__)
  66 #define PS_USE_CLOBBER_ARGV
  67 #else
  68 #define PS_USE_NONE
  69 #endif
  70
  71
  72 /* Different systems want the buffer padded differently */
  73 #if defined(_AIX3) || defined(__linux__) || defined(__QNX__) || defined(__svr4__)
  74 #define PS_PADDING '\0'
  75 #else
  76 #define PS_PADDING ' '
  77 #endif
  78
  79
  80 #ifndef PS_USE_CLOBBER_ARGV
  81 /* all but one options need a buffer to write their ps line in */
  82 #define PS_BUFFER_SIZE 256
  83 static char ps_buffer[PS_BUFFER_SIZE];
  84 static const size_t ps_buffer_size = PS_BUFFER_SIZE;
  85
  86 #else                                                   /* PS_USE_CLOBBER_ARGV */
  87 static char *ps_buffer;                 /* will point to argv area */
  88 static size_t ps_buffer_size;   /* space determined at run time */
  89
  90 #endif   /* PS_USE_CLOBBER_ARGV */
  91
  92 static size_t ps_buffer_fixed_size;             /* size of the constant prefix */
  93
  94
  95
  96 /*
  97  * Call this once at backend start.
  98  */
  99 void
 100 init_ps_display(int argc, char *argv[],
 101                                 const char *username, const char *dbname,
 102                                 const char *host_info)
 103 {
 104 #ifndef PS_USE_NONE
 105         Assert(username);
 106         Assert(dbname);
 107
 108         /* no ps display for stand-alone backend */
 109         if (!IsUnderPostmaster)
 110                 return;
 111
 112 #ifdef PS_USE_CHANGE_ARGV
 113         argv[0] = ps_buffer;
 114         argv[1] = NULL;
 115 #endif   /* PS_USE_CHANGE_ARGV */
 116
 117 #ifdef PS_USE_CLOBBER_ARGV
 118
 119         /*
 120          * If we're going to overwrite the argv area, count the space.
 121          */
 122         {
 123                 char       *end_of_area = NULL;
 124                 char      **new_environ;
 125                 int                     i;
 126
 127                 /*
 128                  * check for contiguous argv strings
 129                  */
 130                 for (i = 0; i < argc; i++)
 131                         if (i == 0 || end_of_area + 1 == argv[i])
 132                                 end_of_area = argv[i] + strlen(argv[i]);
 133
 134                 /*
 135                  * check for contiguous environ strings following argv
 136                  */
 137                 for (i = 0; end_of_area != NULL && environ[i] != NULL; i++)
 138                         if (end_of_area + 1 == environ[i])
 139                                 end_of_area = environ[i] + strlen(environ[i]);
 140
 141                 if (end_of_area == NULL)
 142                 {
 143                         ps_buffer = NULL;
 144                         ps_buffer_size = 0;
 145                 }
 146                 else
 147                 {
 148                         ps_buffer = argv[0];
 149                         ps_buffer_size = end_of_area - argv[0] - 1;
 150                 }
 151                 argv[1] = NULL;
 152
 153                 /*
 154                  * move the environment out of the way
 155                  */
 156                 for (i = 0; environ[i] != NULL; i++)
 157                         ;
 158                 new_environ = malloc(sizeof(char *) * (i + 1));
 159                 for (i = 0; environ[i] != NULL; i++)
 160                         new_environ[i] = strdup(environ[i]);
 161                 new_environ[i] = NULL;
 162                 environ = new_environ;
 163         }
 164 #endif   /* PS_USE_CLOBBER_ARGV */
 165
 166         /*
 167          * Make fixed prefix
 168          */
 169 #ifdef PS_USE_SETPROCTITLE
 170
 171         /*
 172          * apparently setproctitle() already adds a `progname:' prefix to the
 173          * ps line
 174          */
 175         snprintf(ps_buffer, ps_buffer_size,
 176                          "%s %s %s ",
 177                          username, dbname, host_info);
 178 #else
 179         snprintf(ps_buffer, ps_buffer_size,
 180                          "postgres: %s %s %s ",
 181                          username, dbname, host_info);
 182 #endif
 183
 184         ps_buffer_fixed_size = strlen(ps_buffer);
 185 #endif   /* not PS_USE_NONE */
 186 }
 187
 188
 189
 190 /*
 191  * Call this to update the ps status display to a fixed prefix plus an
 192  * indication of what you're currently doing passed in the argument.
 193  */
 194 void
 195 set_ps_display(const char *value)
 196 {
 197 #ifndef PS_USE_NONE
 198         /* no ps display for stand-alone backend */
 199         if (!IsUnderPostmaster)
 200                 return;
 201
 202 #ifdef PS_USE_CLOBBER_ARGV
 203         /* If ps_buffer is a pointer, it might still be null */
 204         if (!ps_buffer)
 205                 return;
 206 #endif
 207
 208         /* Update ps_buffer to contain both fixed part and value */
 209         StrNCpy(ps_buffer + ps_buffer_fixed_size, value,
 210                         ps_buffer_size - ps_buffer_fixed_size);
 211
 212         /* Transmit new setting to kernel, if necessary */
 213
 214 #ifdef PS_USE_SETPROCTITLE
 215         setproctitle("%s", ps_buffer);
 216 #endif
 217
 218 #ifdef PS_USE_PSTAT
 219         {
 220                 union pstun pst;
 221
 222                 pst.pst_command = ps_buffer;
 223                 pstat(PSTAT_SETCMD, pst, strlen(ps_buffer), 0, 0);
 224         }
 225 #endif   /* PS_USE_PSTAT */
 226
 227 #ifdef PS_USE_PS_STRINGS
 228         PS_STRINGS->ps_nargvstr = 1;
 229         PS_STRINGS->ps_argvstr = ps_buffer;
 230 #endif   /* PS_USE_PS_STRINGS */
 231
 232 #ifdef PS_USE_CLOBBER_ARGV
 233         {
 234                 char       *cp;
 235
 236                 /* pad unused memory */
 237                 for (cp = ps_buffer + strlen(ps_buffer);
 238                          cp < ps_buffer + ps_buffer_size;
 239                          cp++)
 240                         *cp = PS_PADDING;
 241         }
 242 #endif   /* PS_USE_CLOBBER_ARGV */
 243
 244 #endif   /* not PS_USE_NONE */
 245 }
 246
 247
 248 /*
 249  * Returns what's currently in the ps display, in case someone needs
 250  * it.  Note that only the variable part is returned.
 251  */
 252 const char *
 253 get_ps_display(void)
 254 {
 255 #ifdef PS_USE_CLOBBER_ARGV
 256         /* If ps_buffer is a pointer, it might still be null */
 257         if (!ps_buffer)
 258                 return "";
 259 #endif
 260
 261         return ps_buffer + ps_buffer_fixed_size;
 262 }