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) 2000-2018, 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
34 extern char **environ;
35 bool update_process_title = true;
36
37
38 /*
39 * Alternative ways of updating ps display:
40 *
41 * PS_USE_SETPROCTITLE
42 * use the function setproctitle(const char *, ...)
43 * (newer BSD systems)
44 * PS_USE_PSTAT
45 * use the pstat(PSTAT_SETCMD, )
46 * (HPUX)
47 * PS_USE_PS_STRINGS
48 * assign PS_STRINGS->ps_argvstr = "string"
49 * (some BSD systems)
50 * PS_USE_CHANGE_ARGV
51 * assign argv[0] = "string"
52 * (some other BSD systems)
53 * PS_USE_CLOBBER_ARGV
54 * write over the argv and environment area
55 * (Linux and most SysV-like systems)
56 * PS_USE_WIN32
57 * push the string out as the name of a Windows event
58 * PS_USE_NONE
59 * don't update ps display
60 * (This is the default, as it is safest.)
61 */
62 #if defined(HAVE_SETPROCTITLE)
63 #define PS_USE_SETPROCTITLE
64 #elif defined(HAVE_PSTAT) && defined(PSTAT_SETCMD)
65 #define PS_USE_PSTAT
66 #elif defined(HAVE_PS_STRINGS)
67 #define PS_USE_PS_STRINGS
68 #elif (defined(BSD) || defined(__hurd__)) && !defined(__darwin__)
69 #define PS_USE_CHANGE_ARGV
70 #elif defined(__linux__) || defined(_AIX) || defined(__sgi) || (defined(sun) && !defined(BSD)) || defined(__svr5__) || defined(__darwin__)
71 #define PS_USE_CLOBBER_ARGV
72 #elif defined(WIN32)
73 #define PS_USE_WIN32
74 #else
75 #define PS_USE_NONE
76 #endif
77
78
79 /* Different systems want the buffer padded differently */
80 #if defined(_AIX) || defined(__linux__) || defined(__darwin__)
81 #define PS_PADDING '\0'
82 #else
83 #define PS_PADDING ' '
84 #endif
85
86
87 #ifndef PS_USE_CLOBBER_ARGV
88 /* all but one option need a buffer to write their ps line in */
89 #define PS_BUFFER_SIZE 256
90 static char ps_buffer[PS_BUFFER_SIZE];
91 static const size_t ps_buffer_size = PS_BUFFER_SIZE;
92 #else /* PS_USE_CLOBBER_ARGV */
93 static char *ps_buffer; /* will point to argv area */
94 static size_t ps_buffer_size; /* space determined at run time */
95 static size_t last_status_len; /* use to minimize length of clobber */
96 #endif /* PS_USE_CLOBBER_ARGV */
97
98 static size_t ps_buffer_cur_len; /* nominal strlen(ps_buffer) */
99
100 static size_t ps_buffer_fixed_size; /* size of the constant prefix */
101
102 /* save the original argv[] location here */
103 static int save_argc;
104 static char **save_argv;
105
106
107 /*
108 * Call this early in startup to save the original argc/argv values.
109 * If needed, we make a copy of the original argv[] array to preserve it
110 * from being clobbered by subsequent ps_display actions.
111 *
112 * (The original argv[] will not be overwritten by this routine, but may be
113 * overwritten during init_ps_display. Also, the physical location of the
114 * environment strings may be moved, so this should be called before any code
115 * that might try to hang onto a getenv() result.)
116 *
117 * Note that in case of failure this cannot call elog() as that is not
118 * initialized yet. We rely on write_stderr() instead.
119 */
120 char **
save_ps_display_args(int argc,char ** argv)121 save_ps_display_args(int argc, char **argv)
122 {
123 save_argc = argc;
124 save_argv = argv;
125
126 #if defined(PS_USE_CLOBBER_ARGV)
127
128 /*
129 * If we're going to overwrite the argv area, count the available space.
130 * Also move the environment to make additional room.
131 */
132 {
133 char *end_of_area = NULL;
134 char **new_environ;
135 int i;
136
137 /*
138 * check for contiguous argv strings
139 */
140 for (i = 0; i < argc; i++)
141 {
142 if (i == 0 || end_of_area + 1 == argv[i])
143 end_of_area = argv[i] + strlen(argv[i]);
144 }
145
146 if (end_of_area == NULL) /* probably can't happen? */
147 {
148 ps_buffer = NULL;
149 ps_buffer_size = 0;
150 return argv;
151 }
152
153 /*
154 * check for contiguous environ strings following argv
155 */
156 for (i = 0; environ[i] != NULL; i++)
157 {
158 if (end_of_area + 1 == environ[i])
159 end_of_area = environ[i] + strlen(environ[i]);
160 }
161
162 ps_buffer = argv[0];
163 last_status_len = ps_buffer_size = end_of_area - argv[0];
164
165 /*
166 * move the environment out of the way
167 */
168 new_environ = (char **) malloc((i + 1) * sizeof(char *));
169 if (!new_environ)
170 {
171 write_stderr("out of memory\n");
172 exit(1);
173 }
174 for (i = 0; environ[i] != NULL; i++)
175 {
176 new_environ[i] = strdup(environ[i]);
177 if (!new_environ[i])
178 {
179 write_stderr("out of memory\n");
180 exit(1);
181 }
182 }
183 new_environ[i] = NULL;
184 environ = new_environ;
185 }
186 #endif /* PS_USE_CLOBBER_ARGV */
187
188 #if defined(PS_USE_CHANGE_ARGV) || defined(PS_USE_CLOBBER_ARGV)
189
190 /*
191 * If we're going to change the original argv[] then make a copy for
192 * argument parsing purposes.
193 *
194 * (NB: do NOT think to remove the copying of argv[], even though
195 * postmaster.c finishes looking at argv[] long before we ever consider
196 * changing the ps display. On some platforms, getopt() keeps pointers
197 * into the argv array, and will get horribly confused when it is
198 * re-called to analyze a subprocess' argument string if the argv storage
199 * has been clobbered meanwhile. Other platforms have other dependencies
200 * on argv[].
201 */
202 {
203 char **new_argv;
204 int i;
205
206 new_argv = (char **) malloc((argc + 1) * sizeof(char *));
207 if (!new_argv)
208 {
209 write_stderr("out of memory\n");
210 exit(1);
211 }
212 for (i = 0; i < argc; i++)
213 {
214 new_argv[i] = strdup(argv[i]);
215 if (!new_argv[i])
216 {
217 write_stderr("out of memory\n");
218 exit(1);
219 }
220 }
221 new_argv[argc] = NULL;
222
223 #if defined(__darwin__)
224
225 /*
226 * macOS (and perhaps other NeXT-derived platforms?) has a static copy
227 * of the argv pointer, which we may fix like so:
228 */
229 *_NSGetArgv() = new_argv;
230 #endif
231
232 argv = new_argv;
233 }
234 #endif /* PS_USE_CHANGE_ARGV or PS_USE_CLOBBER_ARGV */
235
236 return argv;
237 }
238
239 /*
240 * Call this once during subprocess startup to set the identification
241 * values. At this point, the original argv[] array may be overwritten.
242 */
243 void
init_ps_display(const char * username,const char * dbname,const char * host_info,const char * initial_str)244 init_ps_display(const char *username, const char *dbname,
245 const char *host_info, const char *initial_str)
246 {
247 Assert(username);
248 Assert(dbname);
249 Assert(host_info);
250
251 #ifndef PS_USE_NONE
252 /* no ps display for stand-alone backend */
253 if (!IsUnderPostmaster)
254 return;
255
256 /* no ps display if you didn't call save_ps_display_args() */
257 if (!save_argv)
258 return;
259
260 #ifdef PS_USE_CLOBBER_ARGV
261 /* If ps_buffer is a pointer, it might still be null */
262 if (!ps_buffer)
263 return;
264 #endif
265
266 /*
267 * Overwrite argv[] to point at appropriate space, if needed
268 */
269
270 #ifdef PS_USE_CHANGE_ARGV
271 save_argv[0] = ps_buffer;
272 save_argv[1] = NULL;
273 #endif /* PS_USE_CHANGE_ARGV */
274
275 #ifdef PS_USE_CLOBBER_ARGV
276 {
277 int i;
278
279 /* make extra argv slots point at end_of_area (a NUL) */
280 for (i = 1; i < save_argc; i++)
281 save_argv[i] = ps_buffer + ps_buffer_size;
282 }
283 #endif /* PS_USE_CLOBBER_ARGV */
284
285 /*
286 * Make fixed prefix of ps display.
287 */
288
289 #ifdef PS_USE_SETPROCTITLE
290
291 /*
292 * apparently setproctitle() already adds a `progname:' prefix to the ps
293 * line
294 */
295 #define PROGRAM_NAME_PREFIX ""
296 #else
297 #define PROGRAM_NAME_PREFIX "postgres: "
298 #endif
299
300 if (*cluster_name == '\0')
301 {
302 snprintf(ps_buffer, ps_buffer_size,
303 PROGRAM_NAME_PREFIX "%s %s %s ",
304 username, dbname, host_info);
305 }
306 else
307 {
308 snprintf(ps_buffer, ps_buffer_size,
309 PROGRAM_NAME_PREFIX "%s: %s %s %s ",
310 cluster_name, username, dbname, host_info);
311 }
312
313 ps_buffer_cur_len = ps_buffer_fixed_size = strlen(ps_buffer);
314
315 set_ps_display(initial_str, true);
316 #endif /* not PS_USE_NONE */
317 }
318
319
320
321 /*
322 * Call this to update the ps status display to a fixed prefix plus an
323 * indication of what you're currently doing passed in the argument.
324 */
325 void
set_ps_display(const char * activity,bool force)326 set_ps_display(const char *activity, bool force)
327 {
328 #ifndef PS_USE_NONE
329 /* update_process_title=off disables updates, unless force = true */
330 if (!force && !update_process_title)
331 return;
332
333 /* no ps display for stand-alone backend */
334 if (!IsUnderPostmaster)
335 return;
336
337 #ifdef PS_USE_CLOBBER_ARGV
338 /* If ps_buffer is a pointer, it might still be null */
339 if (!ps_buffer)
340 return;
341 #endif
342
343 /* Update ps_buffer to contain both fixed part and activity */
344 strlcpy(ps_buffer + ps_buffer_fixed_size, activity,
345 ps_buffer_size - ps_buffer_fixed_size);
346 ps_buffer_cur_len = strlen(ps_buffer);
347
348 /* Transmit new setting to kernel, if necessary */
349
350 #ifdef PS_USE_SETPROCTITLE
351 setproctitle("%s", ps_buffer);
352 #endif
353
354 #ifdef PS_USE_PSTAT
355 {
356 union pstun pst;
357
358 pst.pst_command = ps_buffer;
359 pstat(PSTAT_SETCMD, pst, ps_buffer_cur_len, 0, 0);
360 }
361 #endif /* PS_USE_PSTAT */
362
363 #ifdef PS_USE_PS_STRINGS
364 PS_STRINGS->ps_nargvstr = 1;
365 PS_STRINGS->ps_argvstr = ps_buffer;
366 #endif /* PS_USE_PS_STRINGS */
367
368 #ifdef PS_USE_CLOBBER_ARGV
369 /* pad unused memory; need only clobber remainder of old status string */
370 if (last_status_len > ps_buffer_cur_len)
371 MemSet(ps_buffer + ps_buffer_cur_len, PS_PADDING,
372 last_status_len - ps_buffer_cur_len);
373 last_status_len = ps_buffer_cur_len;
374 #endif /* PS_USE_CLOBBER_ARGV */
375
376 #ifdef PS_USE_WIN32
377 {
378 /*
379 * Win32 does not support showing any changed arguments. To make it at
380 * all possible to track which backend is doing what, we create a
381 * named object that can be viewed with for example Process Explorer.
382 */
383 static HANDLE ident_handle = INVALID_HANDLE_VALUE;
384 char name[PS_BUFFER_SIZE + 32];
385
386 if (ident_handle != INVALID_HANDLE_VALUE)
387 CloseHandle(ident_handle);
388
389 sprintf(name, "pgident(%d): %s", MyProcPid, ps_buffer);
390
391 ident_handle = CreateEvent(NULL, TRUE, FALSE, name);
392 }
393 #endif /* PS_USE_WIN32 */
394 #endif /* not PS_USE_NONE */
395 }
396
397
398 /*
399 * Returns what's currently in the ps display, in case someone needs
400 * it. Note that only the activity part is returned. On some platforms
401 * the string will not be null-terminated, so return the effective
402 * length into *displen.
403 */
404 const char *
get_ps_display(int * displen)405 get_ps_display(int *displen)
406 {
407 #ifdef PS_USE_CLOBBER_ARGV
408 /* If ps_buffer is a pointer, it might still be null */
409 if (!ps_buffer)
410 {
411 *displen = 0;
412 return "";
413 }
414 #endif
415
416 *displen = (int) (ps_buffer_cur_len - ps_buffer_fixed_size);
417
418 return ps_buffer + ps_buffer_fixed_size;
419 }
420