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) 2000-2021, 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;
36 bool update_process_title = true;
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 **
save_ps_display_args(int argc,char ** argv)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
init_ps_display(const char * fixed_part)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
set_ps_display(const char * activity)349 set_ps_display(const char *activity)
350 {
351 #ifndef PS_USE_NONE
352 /* update_process_title=off disables updates */
353 if (!update_process_title)
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 *
get_ps_display(int * displen)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 }
449