PostgreSQL Source Code: src/backend/utils/misc/ps_status.c Source File

PostgreSQL Source Code git master
ps_status.c
Go to the documentation of this file.
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) 2000-2025, PostgreSQL Global Development Group
11 * various details abducted from various places
12 *--------------------------------------------------------------------
13 */
14
15#include "postgres.h"
16
17#include <unistd.h>
18#if defined(__darwin__)
19#include <crt_externs.h>
20#endif
21
22#include "miscadmin.h"
23#include "utils/guc.h"
24#include "utils/ps_status.h"
25
26#if !defined(WIN32) || defined(_MSC_VER)
27extern char **environ;
28#endif
29
30/* GUC variable */
31 bool update_process_title = DEFAULT_UPDATE_PROCESS_TITLE;
32
33/*
34 * Alternative ways of updating ps display:
35 *
36 * PS_USE_SETPROCTITLE_FAST
37 * use the function setproctitle_fast(const char *, ...)
38 * (FreeBSD)
39 * PS_USE_SETPROCTITLE
40 * use the function setproctitle(const char *, ...)
41 * (other BSDs)
42 * PS_USE_CLOBBER_ARGV
43 * write over the argv and environment area
44 * (Linux and most SysV-like systems)
45 * PS_USE_WIN32
46 * push the string out as the name of a Windows event
47 * PS_USE_NONE
48 * don't update ps display
49 * (This is the default, as it is safest.)
50 */
51#if defined(HAVE_SETPROCTITLE_FAST)
52#define PS_USE_SETPROCTITLE_FAST
53#elif defined(HAVE_SETPROCTITLE)
54#define PS_USE_SETPROCTITLE
55#elif defined(__linux__) || defined(__sun) || defined(__darwin__)
56#define PS_USE_CLOBBER_ARGV
57#elif defined(WIN32)
58#define PS_USE_WIN32
59#else
60 #define PS_USE_NONE
61#endif
62
63
64/* Different systems want the buffer padded differently */
65#if defined(__linux__) || defined(__darwin__)
66#define PS_PADDING '0円'
67#else
68 #define PS_PADDING ' '
69#endif
70
71
72#ifndef PS_USE_NONE
73
74#ifndef PS_USE_CLOBBER_ARGV
75/* all but one option need a buffer to write their ps line in */
76#define PS_BUFFER_SIZE 256
77static char ps_buffer[PS_BUFFER_SIZE];
78static const size_t ps_buffer_size = PS_BUFFER_SIZE;
79#else /* PS_USE_CLOBBER_ARGV */
80static char *ps_buffer; /* will point to argv area */
81static size_t ps_buffer_size; /* space determined at run time */
82static size_t last_status_len; /* use to minimize length of clobber */
83#endif /* PS_USE_CLOBBER_ARGV */
84
85static size_t ps_buffer_cur_len; /* nominal strlen(ps_buffer) */
86
87static size_t ps_buffer_fixed_size; /* size of the constant prefix */
88
89/*
90 * Length of ps_buffer before the suffix was appended to the end, or 0 if we
91 * didn't set a suffix.
92 */
93static size_t ps_buffer_nosuffix_len;
94
95static void flush_ps_display(void);
96
97#endif /* not PS_USE_NONE */
98
99/* save the original argv[] location here */
100 static int save_argc;
101 static char **save_argv;
102
103/*
104 * Valgrind seems not to consider the global "environ" variable as a valid
105 * root pointer; so when we allocate a new environment array, it claims that
106 * data is leaked. To fix that, keep our own statically-allocated copy of the
107 * pointer. (Oddly, this doesn't seem to be a problem for "argv".)
108 */
109#if defined(PS_USE_CLOBBER_ARGV) && defined(USE_VALGRIND)
110extern char **ps_status_new_environ;
111char **ps_status_new_environ;
112#endif
113
114
115/*
116 * Call this early in startup to save the original argc/argv values.
117 * If needed, we make a copy of the original argv[] array to preserve it
118 * from being clobbered by subsequent ps_display actions.
119 *
120 * (The original argv[] will not be overwritten by this routine, but may be
121 * overwritten during init_ps_display. Also, the physical location of the
122 * environment strings may be moved, so this should be called before any code
123 * that might try to hang onto a getenv() result. But see hack for musl
124 * within.)
125 *
126 * Note that in case of failure this cannot call elog() as that is not
127 * initialized yet. We rely on write_stderr() instead.
128 */
129char **
130 save_ps_display_args(int argc, char **argv)
131{
132 save_argc = argc;
133 save_argv = argv;
134
135#if defined(PS_USE_CLOBBER_ARGV)
136
137 /*
138 * If we're going to overwrite the argv area, count the available space.
139 * Also move the environment strings to make additional room.
140 */
141 {
142 char *end_of_area = NULL;
143 char **new_environ;
144 int i;
145
146 /*
147 * check for contiguous argv strings
148 */
149 for (i = 0; i < argc; i++)
150 {
151 if (i == 0 || end_of_area + 1 == argv[i])
152 end_of_area = argv[i] + strlen(argv[i]);
153 }
154
155 if (end_of_area == NULL) /* probably can't happen? */
156 {
157 ps_buffer = NULL;
158 ps_buffer_size = 0;
159 return argv;
160 }
161
162 /*
163 * check for contiguous environ strings following argv
164 */
165 for (i = 0; environ[i] != NULL; i++)
166 {
167 if (end_of_area + 1 == environ[i])
168 {
169 /*
170 * The musl dynamic linker keeps a static pointer to the
171 * initial value of LD_LIBRARY_PATH, if that is defined in the
172 * process's environment. Therefore, we must not overwrite the
173 * value of that setting and thus cannot advance end_of_area
174 * beyond it. Musl does not define any identifying compiler
175 * symbol, so we have to do this unless we see a symbol
176 * identifying a Linux libc we know is safe.
177 */
178#if defined(__linux__) && (!defined(__GLIBC__) && !defined(__UCLIBC__))
179 if (strncmp(environ[i], "LD_LIBRARY_PATH=", 16) == 0)
180 {
181 /*
182 * We can overwrite the name, but stop at the equals sign.
183 * Future loop iterations will not find any more
184 * contiguous space, but we don't break early because we
185 * need to count the total number of environ[] entries.
186 */
187 end_of_area = environ[i] + 15;
188 }
189 else
190#endif
191 {
192 end_of_area = environ[i] + strlen(environ[i]);
193 }
194 }
195 }
196
197 ps_buffer = argv[0];
198 last_status_len = ps_buffer_size = end_of_area - argv[0];
199
200 /*
201 * move the environment out of the way
202 */
203 new_environ = (char **) malloc((i + 1) * sizeof(char *));
204 if (!new_environ)
205 {
206 write_stderr("out of memory\n");
207 exit(1);
208 }
209 for (i = 0; environ[i] != NULL; i++)
210 {
211 new_environ[i] = strdup(environ[i]);
212 if (!new_environ[i])
213 {
214 write_stderr("out of memory\n");
215 exit(1);
216 }
217 }
218 new_environ[i] = NULL;
219 environ = new_environ;
220
221 /* See notes about Valgrind above. */
222#ifdef USE_VALGRIND
223 ps_status_new_environ = new_environ;
224#endif
225 }
226
227 /*
228 * If we're going to change the original argv[] then make a copy for
229 * argument parsing purposes.
230 *
231 * NB: do NOT think to remove the copying of argv[], even though
232 * postmaster.c finishes looking at argv[] long before we ever consider
233 * changing the ps display. On some platforms, getopt() keeps pointers
234 * into the argv array, and will get horribly confused when it is
235 * re-called to analyze a subprocess' argument string if the argv storage
236 * has been clobbered meanwhile. Other platforms have other dependencies
237 * on argv[].
238 */
239 {
240 char **new_argv;
241 int i;
242
243 new_argv = (char **) malloc((argc + 1) * sizeof(char *));
244 if (!new_argv)
245 {
246 write_stderr("out of memory\n");
247 exit(1);
248 }
249 for (i = 0; i < argc; i++)
250 {
251 new_argv[i] = strdup(argv[i]);
252 if (!new_argv[i])
253 {
254 write_stderr("out of memory\n");
255 exit(1);
256 }
257 }
258 new_argv[argc] = NULL;
259
260#if defined(__darwin__)
261
262 /*
263 * macOS has a static copy of the argv pointer, which we may fix like
264 * so:
265 */
266 *_NSGetArgv() = new_argv;
267#endif
268
269 argv = new_argv;
270 }
271#endif /* PS_USE_CLOBBER_ARGV */
272
273 return argv;
274}
275
276/*
277 * Call this once during subprocess startup to set the identification
278 * values.
279 *
280 * If fixed_part is NULL, a default will be obtained from MyBackendType.
281 *
282 * At this point, the original argv[] array may be overwritten.
283 */
284void
285 init_ps_display(const char *fixed_part)
286{
287#ifndef PS_USE_NONE
288 bool save_update_process_title;
289#endif
290
291 Assert(fixed_part || MyBackendType);
292 if (!fixed_part)
293 fixed_part = GetBackendTypeDesc(MyBackendType);
294
295#ifndef PS_USE_NONE
296 /* no ps display for stand-alone backend */
297 if (!IsUnderPostmaster)
298 return;
299
300 /* no ps display if you didn't call save_ps_display_args() */
301 if (!save_argv)
302 return;
303
304#ifdef PS_USE_CLOBBER_ARGV
305 /* If ps_buffer is a pointer, it might still be null */
306 if (!ps_buffer)
307 return;
308
309 /* make extra argv slots point at end_of_area (a NUL) */
310 for (int i = 1; i < save_argc; i++)
311 save_argv[i] = ps_buffer + ps_buffer_size;
312#endif /* PS_USE_CLOBBER_ARGV */
313
314 /*
315 * Make fixed prefix of ps display.
316 */
317
318#if defined(PS_USE_SETPROCTITLE) || defined(PS_USE_SETPROCTITLE_FAST)
319
320 /*
321 * apparently setproctitle() already adds a `progname:' prefix to the ps
322 * line
323 */
324#define PROGRAM_NAME_PREFIX ""
325#else
326#define PROGRAM_NAME_PREFIX "postgres: "
327#endif
328
329 if (*cluster_name == '0円')
330 {
331 snprintf(ps_buffer, ps_buffer_size,
332 PROGRAM_NAME_PREFIX "%s ",
333 fixed_part);
334 }
335 else
336 {
337 snprintf(ps_buffer, ps_buffer_size,
338 PROGRAM_NAME_PREFIX "%s: %s ",
339 cluster_name, fixed_part);
340 }
341
342 ps_buffer_cur_len = ps_buffer_fixed_size = strlen(ps_buffer);
343
344 /*
345 * On the first run, force the update.
346 */
347 save_update_process_title = update_process_title;
348 update_process_title = true;
349 set_ps_display("");
350 update_process_title = save_update_process_title;
351#endif /* not PS_USE_NONE */
352}
353
354#ifndef PS_USE_NONE
355/*
356 * update_ps_display_precheck
357 * Helper function to determine if updating the process title is
358 * something that we need to do.
359 */
360static bool
361update_ps_display_precheck(void)
362{
363 /* update_process_title=off disables updates */
364 if (!update_process_title)
365 return false;
366
367 /* no ps display for stand-alone backend */
368 if (!IsUnderPostmaster)
369 return false;
370
371#ifdef PS_USE_CLOBBER_ARGV
372 /* If ps_buffer is a pointer, it might still be null */
373 if (!ps_buffer)
374 return false;
375#endif
376
377 return true;
378}
379#endif /* not PS_USE_NONE */
380
381/*
382 * set_ps_display_suffix
383 * Adjust the process title to append 'suffix' onto the end with a space
384 * between it and the current process title.
385 */
386void
387 set_ps_display_suffix(const char *suffix)
388{
389#ifndef PS_USE_NONE
390 size_t len;
391
392 /* first, check if we need to update the process title */
393 if (!update_ps_display_precheck())
394 return;
395
396 /* if there's already a suffix, overwrite it */
397 if (ps_buffer_nosuffix_len > 0)
398 ps_buffer_cur_len = ps_buffer_nosuffix_len;
399 else
400 ps_buffer_nosuffix_len = ps_buffer_cur_len;
401
402 len = strlen(suffix);
403
404 /* check if we have enough space to append the suffix */
405 if (ps_buffer_cur_len + len + 1 >= ps_buffer_size)
406 {
407 /* not enough space. Check the buffer isn't full already */
408 if (ps_buffer_cur_len < ps_buffer_size - 1)
409 {
410 /* append a space before the suffix */
411 ps_buffer[ps_buffer_cur_len++] = ' ';
412
413 /* just add what we can and fill the ps_buffer */
414 memcpy(ps_buffer + ps_buffer_cur_len, suffix,
415 ps_buffer_size - ps_buffer_cur_len - 1);
416 ps_buffer[ps_buffer_size - 1] = '0円';
417 ps_buffer_cur_len = ps_buffer_size - 1;
418 }
419 }
420 else
421 {
422 ps_buffer[ps_buffer_cur_len++] = ' ';
423 memcpy(ps_buffer + ps_buffer_cur_len, suffix, len + 1);
424 ps_buffer_cur_len = ps_buffer_cur_len + len;
425 }
426
427 Assert(strlen(ps_buffer) == ps_buffer_cur_len);
428
429 /* and set the new title */
430 flush_ps_display();
431#endif /* not PS_USE_NONE */
432}
433
434/*
435 * set_ps_display_remove_suffix
436 * Remove the process display suffix added by set_ps_display_suffix
437 */
438void
439 set_ps_display_remove_suffix(void)
440{
441#ifndef PS_USE_NONE
442 /* first, check if we need to update the process title */
443 if (!update_ps_display_precheck())
444 return;
445
446 /* check we added a suffix */
447 if (ps_buffer_nosuffix_len == 0)
448 return; /* no suffix */
449
450 /* remove the suffix from ps_buffer */
451 ps_buffer[ps_buffer_nosuffix_len] = '0円';
452 ps_buffer_cur_len = ps_buffer_nosuffix_len;
453 ps_buffer_nosuffix_len = 0;
454
455 Assert(ps_buffer_cur_len == strlen(ps_buffer));
456
457 /* and set the new title */
458 flush_ps_display();
459#endif /* not PS_USE_NONE */
460}
461
462/*
463 * Call this to update the ps status display to a fixed prefix plus an
464 * indication of what you're currently doing passed in the argument.
465 *
466 * 'len' must be the same as strlen(activity)
467 */
468void
469 set_ps_display_with_len(const char *activity, size_t len)
470{
471 Assert(strlen(activity) == len);
472
473#ifndef PS_USE_NONE
474 /* first, check if we need to update the process title */
475 if (!update_ps_display_precheck())
476 return;
477
478 /* wipe out any suffix when the title is completely changed */
479 ps_buffer_nosuffix_len = 0;
480
481 /* Update ps_buffer to contain both fixed part and activity */
482 if (ps_buffer_fixed_size + len >= ps_buffer_size)
483 {
484 /* handle the case where ps_buffer doesn't have enough space */
485 memcpy(ps_buffer + ps_buffer_fixed_size, activity,
486 ps_buffer_size - ps_buffer_fixed_size - 1);
487 ps_buffer[ps_buffer_size - 1] = '0円';
488 ps_buffer_cur_len = ps_buffer_size - 1;
489 }
490 else
491 {
492 memcpy(ps_buffer + ps_buffer_fixed_size, activity, len + 1);
493 ps_buffer_cur_len = ps_buffer_fixed_size + len;
494 }
495 Assert(strlen(ps_buffer) == ps_buffer_cur_len);
496
497 /* Transmit new setting to kernel, if necessary */
498 flush_ps_display();
499#endif /* not PS_USE_NONE */
500}
501
502#ifndef PS_USE_NONE
503static void
504flush_ps_display(void)
505{
506#ifdef PS_USE_SETPROCTITLE
507 setproctitle("%s", ps_buffer);
508#elif defined(PS_USE_SETPROCTITLE_FAST)
509 setproctitle_fast("%s", ps_buffer);
510#endif
511
512#ifdef PS_USE_CLOBBER_ARGV
513 /* pad unused memory; need only clobber remainder of old status string */
514 if (last_status_len > ps_buffer_cur_len)
515 MemSet(ps_buffer + ps_buffer_cur_len, PS_PADDING,
516 last_status_len - ps_buffer_cur_len);
517 last_status_len = ps_buffer_cur_len;
518#endif /* PS_USE_CLOBBER_ARGV */
519
520#ifdef PS_USE_WIN32
521 {
522 /*
523 * Win32 does not support showing any changed arguments. To make it at
524 * all possible to track which backend is doing what, we create a
525 * named object that can be viewed with for example Process Explorer.
526 */
527 static HANDLE ident_handle = INVALID_HANDLE_VALUE;
528 char name[PS_BUFFER_SIZE + 32];
529
530 if (ident_handle != INVALID_HANDLE_VALUE)
531 CloseHandle(ident_handle);
532
533 sprintf(name, "pgident(%d): %s", MyProcPid, ps_buffer);
534
535 ident_handle = CreateEvent(NULL, TRUE, FALSE, name);
536 }
537#endif /* PS_USE_WIN32 */
538}
539#endif /* not PS_USE_NONE */
540
541/*
542 * Returns what's currently in the ps display, in case someone needs
543 * it. Note that only the activity part is returned. On some platforms
544 * the string will not be null-terminated, so return the effective
545 * length into *displen.
546 */
547const char *
548 get_ps_display(int *displen)
549{
550#ifdef PS_USE_CLOBBER_ARGV
551 /* If ps_buffer is a pointer, it might still be null */
552 if (!ps_buffer)
553 {
554 *displen = 0;
555 return "";
556 }
557#endif
558
559#ifndef PS_USE_NONE
560 *displen = (int) (ps_buffer_cur_len - ps_buffer_fixed_size);
561
562 return ps_buffer + ps_buffer_fixed_size;
563#else
564 *displen = 0;
565 return "";
566#endif
567}
#define write_stderr(str)
Definition: parallel.c:186
#define MemSet(start, val, len)
Definition: c.h:1019
int MyProcPid
Definition: globals.c:47
bool IsUnderPostmaster
Definition: globals.c:120
char * cluster_name
Definition: guc_tables.c:555
Assert(PointerIsAligned(start, uint64))
#define malloc(a)
Definition: header.h:50
i
int i
Definition: isn.c:77
const char * GetBackendTypeDesc(BackendType backendType)
Definition: miscinit.c:263
BackendType MyBackendType
Definition: miscinit.c:64
const void size_t len
#define sprintf
Definition: port.h:241
#define snprintf
Definition: port.h:239
#define PS_PADDING
Definition: ps_status.c:68
const char * get_ps_display(int *displen)
Definition: ps_status.c:548
static int save_argc
Definition: ps_status.c:100
void set_ps_display_remove_suffix(void)
Definition: ps_status.c:439
void set_ps_display_with_len(const char *activity, size_t len)
Definition: ps_status.c:469
void init_ps_display(const char *fixed_part)
Definition: ps_status.c:285
void set_ps_display_suffix(const char *suffix)
Definition: ps_status.c:387
char ** environ
bool update_process_title
Definition: ps_status.c:31
char ** save_ps_display_args(int argc, char **argv)
Definition: ps_status.c:130
static char ** save_argv
Definition: ps_status.c:101
static void set_ps_display(const char *activity)
Definition: ps_status.h:40
#define DEFAULT_UPDATE_PROCESS_TITLE
Definition: ps_status.h:19
const char * name

AltStyle によって変換されたページ (->オリジナル) /