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ps_status.c
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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  * src/backend/utils/misc/ps_status.c
9  *
10  * Copyright (c) 2000-2020, 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 "pgstat.h"
32 #include "utils/guc.h"
33 #include "utils/ps_status.h"
34 
35 extern char **environ;
37 
38 
39 /*
40  * Alternative ways of updating ps display:
41  *
42  * PS_USE_SETPROCTITLE_FAST
43  * use the function setproctitle_fast(const char *, ...)
44  * (newer FreeBSD systems)
45  * PS_USE_SETPROCTITLE
46  * use the function setproctitle(const char *, ...)
47  * (newer BSD systems)
48  * PS_USE_PSTAT
49  * use the pstat(PSTAT_SETCMD, )
50  * (HPUX)
51  * PS_USE_PS_STRINGS
52  * assign PS_STRINGS->ps_argvstr = "string"
53  * (some BSD systems)
54  * PS_USE_CHANGE_ARGV
55  * assign argv[0] = "string"
56  * (some other BSD systems)
57  * PS_USE_CLOBBER_ARGV
58  * write over the argv and environment area
59  * (Linux and most SysV-like systems)
60  * PS_USE_WIN32
61  * push the string out as the name of a Windows event
62  * PS_USE_NONE
63  * don't update ps display
64  * (This is the default, as it is safest.)
65  */
66 #if defined(HAVE_SETPROCTITLE_FAST)
67 #define PS_USE_SETPROCTITLE_FAST
68 #elif defined(HAVE_SETPROCTITLE)
69 #define PS_USE_SETPROCTITLE
70 #elif defined(HAVE_PSTAT) && defined(PSTAT_SETCMD)
71 #define PS_USE_PSTAT
72 #elif defined(HAVE_PS_STRINGS)
73 #define PS_USE_PS_STRINGS
74 #elif (defined(BSD) || defined(__hurd__)) && !defined(__darwin__)
75 #define PS_USE_CHANGE_ARGV
76 #elif defined(__linux__) || defined(_AIX) || defined(__sgi) || (defined(sun) && !defined(BSD)) || defined(__svr5__) || defined(__darwin__)
77 #define PS_USE_CLOBBER_ARGV
78 #elif defined(WIN32)
79 #define PS_USE_WIN32
80 #else
81 #define PS_USE_NONE
82 #endif
83 
84 
85 /* Different systems want the buffer padded differently */
86 #if defined(_AIX) || defined(__linux__) || defined(__darwin__)
87 #define PS_PADDING '\0'
88 #else
89 #define PS_PADDING ' '
90 #endif
91 
92 
93 #ifndef PS_USE_NONE
94 
95 #ifndef PS_USE_CLOBBER_ARGV
96 /* all but one option need a buffer to write their ps line in */
97 #define PS_BUFFER_SIZE 256
98 static char ps_buffer[PS_BUFFER_SIZE];
99 static const size_t ps_buffer_size = PS_BUFFER_SIZE;
100 #else /* PS_USE_CLOBBER_ARGV */
101 static char *ps_buffer; /* will point to argv area */
102 static size_t ps_buffer_size; /* space determined at run time */
103 static size_t last_status_len; /* use to minimize length of clobber */
104 #endif /* PS_USE_CLOBBER_ARGV */
105 
106 static size_t ps_buffer_cur_len; /* nominal strlen(ps_buffer) */
107 
108 static size_t ps_buffer_fixed_size; /* size of the constant prefix */
109 
110 #endif /* not PS_USE_NONE */
111 
112 /* save the original argv[] location here */
113 static int save_argc;
114 static char **save_argv;
115 
116 
117 /*
118  * Call this early in startup to save the original argc/argv values.
119  * If needed, we make a copy of the original argv[] array to preserve it
120  * from being clobbered by subsequent ps_display actions.
121  *
122  * (The original argv[] will not be overwritten by this routine, but may be
123  * overwritten during init_ps_display. Also, the physical location of the
124  * environment strings may be moved, so this should be called before any code
125  * that might try to hang onto a getenv() result.)
126  *
127  * Note that in case of failure this cannot call elog() as that is not
128  * initialized yet. We rely on write_stderr() instead.
129  */
130 char **
131 save_ps_display_args(int argc, char **argv)
132 {
133  save_argc = argc;
134  save_argv = argv;
135 
136 #if defined(PS_USE_CLOBBER_ARGV)
137 
138  /*
139  * If we're going to overwrite the argv area, count the available space.
140  * Also move the environment to make additional room.
141  */
142  {
143  char *end_of_area = NULL;
144  char **new_environ;
145  int i;
146 
147  /*
148  * check for contiguous argv strings
149  */
150  for (i = 0; i < argc; i++)
151  {
152  if (i == 0 || end_of_area + 1 == argv[i])
153  end_of_area = argv[i] + strlen(argv[i]);
154  }
155 
156  if (end_of_area == NULL) /* probably can't happen? */
157  {
158  ps_buffer = NULL;
159  ps_buffer_size = 0;
160  return argv;
161  }
162 
163  /*
164  * check for contiguous environ strings following argv
165  */
166  for (i = 0; environ[i] != NULL; i++)
167  {
168  if (end_of_area + 1 == environ[i])
169  end_of_area = environ[i] + strlen(environ[i]);
170  }
171 
172  ps_buffer = argv[0];
173  last_status_len = ps_buffer_size = end_of_area - argv[0];
174 
175  /*
176  * move the environment out of the way
177  */
178  new_environ = (char **) malloc((i + 1) * sizeof(char *));
179  if (!new_environ)
180  {
181  write_stderr("out of memory\n");
182  exit(1);
183  }
184  for (i = 0; environ[i] != NULL; i++)
185  {
186  new_environ[i] = strdup(environ[i]);
187  if (!new_environ[i])
188  {
189  write_stderr("out of memory\n");
190  exit(1);
191  }
192  }
193  new_environ[i] = NULL;
194  environ = new_environ;
195  }
196 #endif /* PS_USE_CLOBBER_ARGV */
197 
198 #if defined(PS_USE_CHANGE_ARGV) || defined(PS_USE_CLOBBER_ARGV)
199 
200  /*
201  * If we're going to change the original argv[] then make a copy for
202  * argument parsing purposes.
203  *
204  * (NB: do NOT think to remove the copying of argv[], even though
205  * postmaster.c finishes looking at argv[] long before we ever consider
206  * changing the ps display. On some platforms, getopt() keeps pointers
207  * into the argv array, and will get horribly confused when it is
208  * re-called to analyze a subprocess' argument string if the argv storage
209  * has been clobbered meanwhile. Other platforms have other dependencies
210  * on argv[].
211  */
212  {
213  char **new_argv;
214  int i;
215 
216  new_argv = (char **) malloc((argc + 1) * sizeof(char *));
217  if (!new_argv)
218  {
219  write_stderr("out of memory\n");
220  exit(1);
221  }
222  for (i = 0; i < argc; i++)
223  {
224  new_argv[i] = strdup(argv[i]);
225  if (!new_argv[i])
226  {
227  write_stderr("out of memory\n");
228  exit(1);
229  }
230  }
231  new_argv[argc] = NULL;
232 
233 #if defined(__darwin__)
234 
235  /*
236  * macOS (and perhaps other NeXT-derived platforms?) has a static copy
237  * of the argv pointer, which we may fix like so:
238  */
239  *_NSGetArgv() = new_argv;
240 #endif
241 
242  argv = new_argv;
243  }
244 #endif /* PS_USE_CHANGE_ARGV or PS_USE_CLOBBER_ARGV */
245 
246  return argv;
247 }
248 
249 /*
250  * Call this once during subprocess startup to set the identification
251  * values.
252  *
253  * If fixed_part is NULL, a default will be obtained from MyBackendType.
254  *
255  * At this point, the original argv[] array may be overwritten.
256  */
257 void
258 init_ps_display(const char *fixed_part)
259 {
260 #ifndef PS_USE_NONE
261  bool save_update_process_title;
262 #endif
263 
264  Assert(fixed_part || MyBackendType);
265  if (!fixed_part)
266  fixed_part = GetBackendTypeDesc(MyBackendType);
267 
268 #ifndef PS_USE_NONE
269  /* no ps display for stand-alone backend */
270  if (!IsUnderPostmaster)
271  return;
272 
273  /* no ps display if you didn't call save_ps_display_args() */
274  if (!save_argv)
275  return;
276 
277 #ifdef PS_USE_CLOBBER_ARGV
278  /* If ps_buffer is a pointer, it might still be null */
279  if (!ps_buffer)
280  return;
281 #endif
282 
283  /*
284  * Overwrite argv[] to point at appropriate space, if needed
285  */
286 
287 #ifdef PS_USE_CHANGE_ARGV
288  save_argv[0] = ps_buffer;
289  save_argv[1] = NULL;
290 #endif /* PS_USE_CHANGE_ARGV */
291 
292 #ifdef PS_USE_CLOBBER_ARGV
293  {
294  int i;
295 
296  /* make extra argv slots point at end_of_area (a NUL) */
297  for (i = 1; i < save_argc; i++)
298  save_argv[i] = ps_buffer + ps_buffer_size;
299  }
300 #endif /* PS_USE_CLOBBER_ARGV */
301 
302  /*
303  * Make fixed prefix of ps display.
304  */
305 
306 #if defined(PS_USE_SETPROCTITLE) || defined(PS_USE_SETPROCTITLE_FAST)
307 
308  /*
309  * apparently setproctitle() already adds a `progname:' prefix to the ps
310  * line
311  */
312 #define PROGRAM_NAME_PREFIX ""
313 #else
314 #define PROGRAM_NAME_PREFIX "postgres: "
315 #endif
316 
317  if (*cluster_name == '\0')
318  {
319  snprintf(ps_buffer, ps_buffer_size,
320  PROGRAM_NAME_PREFIX "%s ",
321  fixed_part);
322  }
323  else
324  {
325  snprintf(ps_buffer, ps_buffer_size,
326  PROGRAM_NAME_PREFIX "%s: %s ",
327  cluster_name, fixed_part);
328  }
329 
330  ps_buffer_cur_len = ps_buffer_fixed_size = strlen(ps_buffer);
331 
332  /*
333  * On the first run, force the update.
334  */
335  save_update_process_title = update_process_title;
336  update_process_title = true;
337  set_ps_display("");
338  update_process_title = save_update_process_title;
339 #endif /* not PS_USE_NONE */
340 }
341 
342 
343 
344 /*
345  * Call this to update the ps status display to a fixed prefix plus an
346  * indication of what you're currently doing passed in the argument.
347  */
348 void
349 set_ps_display(const char *activity)
350 {
351 #ifndef PS_USE_NONE
352  /* update_process_title=off disables updates */
354  return;
355 
356  /* no ps display for stand-alone backend */
357  if (!IsUnderPostmaster)
358  return;
359 
360 #ifdef PS_USE_CLOBBER_ARGV
361  /* If ps_buffer is a pointer, it might still be null */
362  if (!ps_buffer)
363  return;
364 #endif
365 
366  /* Update ps_buffer to contain both fixed part and activity */
367  strlcpy(ps_buffer + ps_buffer_fixed_size, activity,
368  ps_buffer_size - ps_buffer_fixed_size);
369  ps_buffer_cur_len = strlen(ps_buffer);
370 
371  /* Transmit new setting to kernel, if necessary */
372 
373 #ifdef PS_USE_SETPROCTITLE
374  setproctitle("%s", ps_buffer);
375 #elif defined(PS_USE_SETPROCTITLE_FAST)
376  setproctitle_fast("%s", ps_buffer);
377 #endif
378 
379 #ifdef PS_USE_PSTAT
380  {
381  union pstun pst;
382 
383  pst.pst_command = ps_buffer;
384  pstat(PSTAT_SETCMD, pst, ps_buffer_cur_len, 0, 0);
385  }
386 #endif /* PS_USE_PSTAT */
387 
388 #ifdef PS_USE_PS_STRINGS
389  PS_STRINGS->ps_nargvstr = 1;
390  PS_STRINGS->ps_argvstr = ps_buffer;
391 #endif /* PS_USE_PS_STRINGS */
392 
393 #ifdef PS_USE_CLOBBER_ARGV
394  /* pad unused memory; need only clobber remainder of old status string */
395  if (last_status_len > ps_buffer_cur_len)
396  MemSet(ps_buffer + ps_buffer_cur_len, PS_PADDING,
397  last_status_len - ps_buffer_cur_len);
398  last_status_len = ps_buffer_cur_len;
399 #endif /* PS_USE_CLOBBER_ARGV */
400 
401 #ifdef PS_USE_WIN32
402  {
403  /*
404  * Win32 does not support showing any changed arguments. To make it at
405  * all possible to track which backend is doing what, we create a
406  * named object that can be viewed with for example Process Explorer.
407  */
408  static HANDLE ident_handle = INVALID_HANDLE_VALUE;
409  char name[PS_BUFFER_SIZE + 32];
410 
411  if (ident_handle != INVALID_HANDLE_VALUE)
412  CloseHandle(ident_handle);
413 
414  sprintf(name, "pgident(%d): %s", MyProcPid, ps_buffer);
415 
416  ident_handle = CreateEvent(NULL, TRUE, FALSE, name);
417  }
418 #endif /* PS_USE_WIN32 */
419 #endif /* not PS_USE_NONE */
420 }
421 
422 
423 /*
424  * Returns what's currently in the ps display, in case someone needs
425  * it. Note that only the activity part is returned. On some platforms
426  * the string will not be null-terminated, so return the effective
427  * length into *displen.
428  */
429 const char *
430 get_ps_display(int *displen)
431 {
432 #ifdef PS_USE_CLOBBER_ARGV
433  /* If ps_buffer is a pointer, it might still be null */
434  if (!ps_buffer)
435  {
436  *displen = 0;
437  return "";
438  }
439 #endif
440 
441 #ifndef PS_USE_NONE
442  *displen = (int) (ps_buffer_cur_len - ps_buffer_fixed_size);
443 
444  return ps_buffer + ps_buffer_fixed_size;
445 #else
446  return "";
447 #endif
448 }
int MyProcPid
Definition: globals.c:40
const char * GetBackendTypeDesc(BackendType backendType)
Definition: miscinit.c:202
static int save_argc
Definition: ps_status.c:113
bool update_process_title
Definition: ps_status.c:36
BackendType MyBackendType
Definition: miscinit.c:60
#define PS_PADDING
Definition: ps_status.c:89
#define write_stderr(str)
Definition: parallel.c:186
#define MemSet(start, val, len)
Definition: c.h:971
#define malloc(a)
Definition: header.h:50
void set_ps_display(const char *activity)
Definition: ps_status.c:349
#define sprintf
Definition: port.h:195
char ** save_ps_display_args(int argc, char **argv)
Definition: ps_status.c:131
const char * get_ps_display(int *displen)
Definition: ps_status.c:430
bool IsUnderPostmaster
Definition: globals.c:109
char * cluster_name
Definition: guc.c:551
size_t strlcpy(char *dst, const char *src, size_t siz)
Definition: strlcpy.c:45
#define Assert(condition)
Definition: c.h:738
const char * name
Definition: encode.c:561
int i
char ** environ
void init_ps_display(const char *fixed_part)
Definition: ps_status.c:258
#define snprintf
Definition: port.h:193
static char ** save_argv
Definition: ps_status.c:114