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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) 2000-2019, 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 
34 extern char **environ;
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
96 static const size_t ps_buffer_size = PS_BUFFER_SIZE;
97 #else /* PS_USE_CLOBBER_ARGV */
98 static char *ps_buffer; /* will point to argv area */
99 static size_t ps_buffer_size; /* space determined at run time */
100 static size_t last_status_len; /* use to minimize length of clobber */
101 #endif /* PS_USE_CLOBBER_ARGV */
102 
103 static size_t ps_buffer_cur_len; /* nominal strlen(ps_buffer) */
104 
105 static size_t ps_buffer_fixed_size; /* size of the constant prefix */
106 
107 /* save the original argv[] location here */
108 static int save_argc;
109 static 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  */
125 char **
126 save_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  */
248 void
249 init_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++)
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  {
308  PROGRAM_NAME_PREFIX "%s %s %s ",
309  username, dbname, host_info);
310  }
311  else
312  {
314  PROGRAM_NAME_PREFIX "%s: %s %s %s ",
315  cluster_name, username, dbname, host_info);
316  }
317 
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  */
330 void
331 set_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 */
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)
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  */
411 const char *
412 get_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 
426 }
#define TRUE
Definition: ecpglib.h:35
int MyProcPid
Definition: globals.c:40
#define PS_BUFFER_SIZE
Definition: ps_status.c:94
static int save_argc
Definition: ps_status.c:108
bool update_process_title
Definition: ps_status.c:35
#define FALSE
Definition: ecpglib.h:39
#define PS_PADDING
Definition: ps_status.c:88
#define write_stderr(str)
Definition: parallel.c:182
void set_ps_display(const char *activity, bool force)
Definition: ps_status.c:331
#define MemSet(start, val, len)
Definition: c.h:955
static const size_t ps_buffer_size
Definition: ps_status.c:96
#define malloc(a)
Definition: header.h:50
#define sprintf
Definition: port.h:194
char ** save_ps_display_args(int argc, char **argv)
Definition: ps_status.c:126
const char * get_ps_display(int *displen)
Definition: ps_status.c:412
bool IsUnderPostmaster
Definition: globals.c:109
char * cluster_name
Definition: guc.c:521
static char * username
Definition: initdb.c:133
size_t strlcpy(char *dst, const char *src, size_t siz)
Definition: strlcpy.c:45
#define Assert(condition)
Definition: c.h:732
char * dbname
Definition: streamutil.c:52
static size_t ps_buffer_cur_len
Definition: ps_status.c:103
const char * name
Definition: encode.c:521
static size_t ps_buffer_fixed_size
Definition: ps_status.c:105
int i
static char ps_buffer[PS_BUFFER_SIZE]
Definition: ps_status.c:95
char ** environ
#define snprintf
Definition: port.h:192
static char ** save_argv
Definition: ps_status.c:109
void init_ps_display(const char *username, const char *dbname, const char *host_info, const char *initial_str)
Definition: ps_status.c:249