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) 2000-2019, 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#include "utils/guc.h"
33
34extern char **environ;
35bool update_process_title = true;
36
37
38/*
39 * Alternative ways of updating ps display:
40 *
41 * PS_USE_SETPROCTITLE_FAST
42 * use the function setproctitle_fast(const char *, ...)
43 * (newer FreeBSD systems)
44 * PS_USE_SETPROCTITLE
45 * use the function setproctitle(const char *, ...)
46 * (newer BSD systems)
47 * PS_USE_PSTAT
48 * use the pstat(PSTAT_SETCMD, )
49 * (HPUX)
50 * PS_USE_PS_STRINGS
51 * assign PS_STRINGS->ps_argvstr = "string"
52 * (some BSD systems)
53 * PS_USE_CHANGE_ARGV
54 * assign argv[0] = "string"
55 * (some other BSD systems)
56 * PS_USE_CLOBBER_ARGV
57 * write over the argv and environment area
58 * (Linux and most SysV-like systems)
59 * PS_USE_WIN32
60 * push the string out as the name of a Windows event
61 * PS_USE_NONE
62 * don't update ps display
63 * (This is the default, as it is safest.)
64 */
65#if defined(HAVE_SETPROCTITLE_FAST)
66#define PS_USE_SETPROCTITLE_FAST
67#elif defined(HAVE_SETPROCTITLE)
68#define PS_USE_SETPROCTITLE
69#elif defined(HAVE_PSTAT) && defined(PSTAT_SETCMD)
70#define PS_USE_PSTAT
71#elif defined(HAVE_PS_STRINGS)
72#define PS_USE_PS_STRINGS
73#elif (defined(BSD) || defined(__hurd__)) && !defined(__darwin__)
74#define PS_USE_CHANGE_ARGV
75#elif defined(__linux__) || defined(_AIX) || defined(__sgi) || (defined(sun) && !defined(BSD)) || defined(__svr5__) || defined(__darwin__)
76#define PS_USE_CLOBBER_ARGV
77#elif defined(WIN32)
78#define PS_USE_WIN32
79#else
80#define PS_USE_NONE
81#endif
82
83
84/* Different systems want the buffer padded differently */
85#if defined(_AIX) || defined(__linux__) || defined(__darwin__)
86#define PS_PADDING '\0'
87#else
88#define PS_PADDING ' '
89#endif
90
91
92#ifndef PS_USE_CLOBBER_ARGV
93/* all but one option need a buffer to write their ps line in */
94#define PS_BUFFER_SIZE 256
95static char ps_buffer[PS_BUFFER_SIZE];
96static const size_t ps_buffer_size = PS_BUFFER_SIZE;
97#else /* PS_USE_CLOBBER_ARGV */
98static char *ps_buffer; /* will point to argv area */
99static size_t ps_buffer_size; /* space determined at run time */
100static size_t last_status_len; /* use to minimize length of clobber */
101#endif /* PS_USE_CLOBBER_ARGV */
102
103static size_t ps_buffer_cur_len; /* nominal strlen(ps_buffer) */
104
105static size_t ps_buffer_fixed_size; /* size of the constant prefix */
106
107/* save the original argv[] location here */
108static int save_argc;
109static char **save_argv;
110
111
112/*
113 * Call this early in startup to save the original argc/argv values.
114 * If needed, we make a copy of the original argv[] array to preserve it
115 * from being clobbered by subsequent ps_display actions.
116 *
117 * (The original argv[] will not be overwritten by this routine, but may be
118 * overwritten during init_ps_display. Also, the physical location of the
119 * environment strings may be moved, so this should be called before any code
120 * that might try to hang onto a getenv() result.)
121 *
122 * Note that in case of failure this cannot call elog() as that is not
123 * initialized yet. We rely on write_stderr() instead.
124 */
125char **
126save_ps_display_args(int argc, char **argv)
127{
128 save_argc = argc;
129 save_argv = argv;
130
131#if defined(PS_USE_CLOBBER_ARGV)
132
133 /*
134 * If we're going to overwrite the argv area, count the available space.
135 * Also move the environment to make additional room.
136 */
137 {
138 char *end_of_area = NULL;
139 char **new_environ;
140 int i;
141
142 /*
143 * check for contiguous argv strings
144 */
145 for (i = 0; i < argc; i++)
146 {
147 if (i == 0 || end_of_area + 1 == argv[i])
148 end_of_area = argv[i] + strlen(argv[i]);
149 }
150
151 if (end_of_area == NULL) /* probably can't happen? */
152 {
153 ps_buffer = NULL;
154 ps_buffer_size = 0;
155 return argv;
156 }
157
158 /*
159 * check for contiguous environ strings following argv
160 */
161 for (i = 0; environ[i] != NULL; i++)
162 {
163 if (end_of_area + 1 == environ[i])
164 end_of_area = environ[i] + strlen(environ[i]);
165 }
166
167 ps_buffer = argv[0];
168 last_status_len = ps_buffer_size = end_of_area - argv[0];
169
170 /*
171 * move the environment out of the way
172 */
173 new_environ = (char **) malloc((i + 1) * sizeof(char *));
174 if (!new_environ)
175 {
176 write_stderr("out of memory\n");
177 exit(1);
178 }
179 for (i = 0; environ[i] != NULL; i++)
180 {
181 new_environ[i] = strdup(environ[i]);
182 if (!new_environ[i])
183 {
184 write_stderr("out of memory\n");
185 exit(1);
186 }
187 }
188 new_environ[i] = NULL;
189 environ = new_environ;
190 }
191#endif /* PS_USE_CLOBBER_ARGV */
192
193#if defined(PS_USE_CHANGE_ARGV) || defined(PS_USE_CLOBBER_ARGV)
194
195 /*
196 * If we're going to change the original argv[] then make a copy for
197 * argument parsing purposes.
198 *
199 * (NB: do NOT think to remove the copying of argv[], even though
200 * postmaster.c finishes looking at argv[] long before we ever consider
201 * changing the ps display. On some platforms, getopt() keeps pointers
202 * into the argv array, and will get horribly confused when it is
203 * re-called to analyze a subprocess' argument string if the argv storage
204 * has been clobbered meanwhile. Other platforms have other dependencies
205 * on argv[].
206 */
207 {
208 char **new_argv;
209 int i;
210
211 new_argv = (char **) malloc((argc + 1) * sizeof(char *));
212 if (!new_argv)
213 {
214 write_stderr("out of memory\n");
215 exit(1);
216 }
217 for (i = 0; i < argc; i++)
218 {
219 new_argv[i] = strdup(argv[i]);
220 if (!new_argv[i])
221 {
222 write_stderr("out of memory\n");
223 exit(1);
224 }
225 }
226 new_argv[argc] = NULL;
227
228#if defined(__darwin__)
229
230 /*
231 * macOS (and perhaps other NeXT-derived platforms?) has a static copy
232 * of the argv pointer, which we may fix like so:
233 */
234 *_NSGetArgv() = new_argv;
235#endif
236
237 argv = new_argv;
238 }
239#endif /* PS_USE_CHANGE_ARGV or PS_USE_CLOBBER_ARGV */
240
241 return argv;
242}
243
244/*
245 * Call this once during subprocess startup to set the identification
246 * values. At this point, the original argv[] array may be overwritten.
247 */
248void
249init_ps_display(const char *username, const char *dbname,
250 const char *host_info, const char *initial_str)
251{
252 Assert(username);
253 Assert(dbname);
254 Assert(host_info);
255
256#ifndef PS_USE_NONE
257 /* no ps display for stand-alone backend */
258 if (!IsUnderPostmaster)
259 return;
260
261 /* no ps display if you didn't call save_ps_display_args() */
262 if (!save_argv)
263 return;
264
265#ifdef PS_USE_CLOBBER_ARGV
266 /* If ps_buffer is a pointer, it might still be null */
267 if (!ps_buffer)
268 return;
269#endif
270
271 /*
272 * Overwrite argv[] to point at appropriate space, if needed
273 */
274
275#ifdef PS_USE_CHANGE_ARGV
276 save_argv[0] = ps_buffer;
277 save_argv[1] = NULL;
278#endif /* PS_USE_CHANGE_ARGV */
279
280#ifdef PS_USE_CLOBBER_ARGV
281 {
282 int i;
283
284 /* make extra argv slots point at end_of_area (a NUL) */
285 for (i = 1; i < save_argc; i++)
286 save_argv[i] = ps_buffer + ps_buffer_size;
287 }
288#endif /* PS_USE_CLOBBER_ARGV */
289
290 /*
291 * Make fixed prefix of ps display.
292 */
293
294#if defined(PS_USE_SETPROCTITLE) || defined(PS_USE_SETPROCTITLE_FAST)
295
296 /*
297 * apparently setproctitle() already adds a `progname:' prefix to the ps
298 * line
299 */
300#define PROGRAM_NAME_PREFIX ""
301#else
302#define PROGRAM_NAME_PREFIX "postgres: "
303#endif
304
305 if (*cluster_name == '\0')
306 {
307 snprintf(ps_buffer, ps_buffer_size,
308 PROGRAM_NAME_PREFIX "%s %s %s ",
309 username, dbname, host_info);
310 }
311 else
312 {
313 snprintf(ps_buffer, ps_buffer_size,
314 PROGRAM_NAME_PREFIX "%s: %s %s %s ",
315 cluster_name, username, dbname, host_info);
316 }
317
318 ps_buffer_cur_len = ps_buffer_fixed_size = strlen(ps_buffer);
319
320 set_ps_display(initial_str, true);
321#endif /* not PS_USE_NONE */
322}
323
324
325
326/*
327 * Call this to update the ps status display to a fixed prefix plus an
328 * indication of what you're currently doing passed in the argument.
329 */
330void
331set_ps_display(const char *activity, bool force)
332{
333#ifndef PS_USE_NONE
334 /* update_process_title=off disables updates, unless force = true */
335 if (!force && !update_process_title)
336 return;
337
338 /* no ps display for stand-alone backend */
339 if (!IsUnderPostmaster)
340 return;
341
342#ifdef PS_USE_CLOBBER_ARGV
343 /* If ps_buffer is a pointer, it might still be null */
344 if (!ps_buffer)
345 return;
346#endif
347
348 /* Update ps_buffer to contain both fixed part and activity */
349 strlcpy(ps_buffer + ps_buffer_fixed_size, activity,
350 ps_buffer_size - ps_buffer_fixed_size);
351 ps_buffer_cur_len = strlen(ps_buffer);
352
353 /* Transmit new setting to kernel, if necessary */
354
355#ifdef PS_USE_SETPROCTITLE
356 setproctitle("%s", ps_buffer);
357#elif defined(PS_USE_SETPROCTITLE_FAST)
358 setproctitle_fast("%s", ps_buffer);
359#endif
360
361#ifdef PS_USE_PSTAT
362 {
363 union pstun pst;
364
365 pst.pst_command = ps_buffer;
366 pstat(PSTAT_SETCMD, pst, ps_buffer_cur_len, 0, 0);
367 }
368#endif /* PS_USE_PSTAT */
369
370#ifdef PS_USE_PS_STRINGS
371 PS_STRINGS->ps_nargvstr = 1;
372 PS_STRINGS->ps_argvstr = ps_buffer;
373#endif /* PS_USE_PS_STRINGS */
374
375#ifdef PS_USE_CLOBBER_ARGV
376 /* pad unused memory; need only clobber remainder of old status string */
377 if (last_status_len > ps_buffer_cur_len)
378 MemSet(ps_buffer + ps_buffer_cur_len, PS_PADDING,
379 last_status_len - ps_buffer_cur_len);
380 last_status_len = ps_buffer_cur_len;
381#endif /* PS_USE_CLOBBER_ARGV */
382
383#ifdef PS_USE_WIN32
384 {
385 /*
386 * Win32 does not support showing any changed arguments. To make it at
387 * all possible to track which backend is doing what, we create a
388 * named object that can be viewed with for example Process Explorer.
389 */
390 static HANDLE ident_handle = INVALID_HANDLE_VALUE;
391 char name[PS_BUFFER_SIZE + 32];
392
393 if (ident_handle != INVALID_HANDLE_VALUE)
394 CloseHandle(ident_handle);
395
396 sprintf(name, "pgident(%d): %s", MyProcPid, ps_buffer);
397
398 ident_handle = CreateEvent(NULL, TRUE, FALSE, name);
399 }
400#endif /* PS_USE_WIN32 */
401#endif /* not PS_USE_NONE */
402}
403
404
405/*
406 * Returns what's currently in the ps display, in case someone needs
407 * it. Note that only the activity part is returned. On some platforms
408 * the string will not be null-terminated, so return the effective
409 * length into *displen.
410 */
411const char *
412get_ps_display(int *displen)
413{
414#ifdef PS_USE_CLOBBER_ARGV
415 /* If ps_buffer is a pointer, it might still be null */
416 if (!ps_buffer)
417 {
418 *displen = 0;
419 return "";
420 }
421#endif
422
423 *displen = (int) (ps_buffer_cur_len - ps_buffer_fixed_size);
424
425 return ps_buffer + ps_buffer_fixed_size;
426}
427