PostgreSQL Source Code  git master
input.c
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1 /*
2  * psql - the PostgreSQL interactive terminal
3  *
4  * Copyright (c) 2000-2022, PostgreSQL Global Development Group
5  *
6  * src/bin/psql/input.c
7  */
8 #include "postgres_fe.h"
9 
10 #ifndef WIN32
11 #include <unistd.h>
12 #endif
13 #include <fcntl.h>
14 #include <limits.h>
15 
16 #include "common.h"
17 #include "common/logging.h"
18 #include "input.h"
19 #include "settings.h"
20 #include "tab-complete.h"
21 
22 #ifndef WIN32
23 #define PSQLHISTORY ".psql_history"
24 #else
25 #define PSQLHISTORY "psql_history"
26 #endif
27 
28 /* Runtime options for turning off readline and history */
29 /* (of course there is no runtime command for doing that :) */
30 #ifdef USE_READLINE
31 static bool useReadline;
32 static bool useHistory;
33 
34 static char *psql_history;
35 
36 static int history_lines_added;
37 
38 
39 /*
40  * Preserve newlines in saved queries by mapping '\n' to NL_IN_HISTORY
41  *
42  * It is assumed NL_IN_HISTORY will never be entered by the user
43  * nor appear inside a multi-byte string. 0x00 is not properly
44  * handled by the readline routines so it can not be used
45  * for this purpose.
46  */
47 #define NL_IN_HISTORY 0x01
48 #endif
49 
50 static void finishInput(void);
51 
52 
53 /*
54  * gets_interactive()
55  *
56  * Gets a line of interactive input, using readline if desired.
57  *
58  * prompt: the prompt string to be used
59  * query_buf: buffer containing lines already read in the current command
60  * (query_buf is not modified here, but may be consulted for tab completion)
61  *
62  * The result is a malloc'd string.
63  *
64  * Caller *must* have set up sigint_interrupt_jmp before calling.
65  */
66 char *
67 gets_interactive(const char *prompt, PQExpBuffer query_buf)
68 {
69 #ifdef USE_READLINE
70  if (useReadline)
71  {
72  char *result;
73 
74  /*
75  * Some versions of readline don't notice SIGWINCH signals that arrive
76  * when not actively reading input. The simplest fix is to always
77  * re-read the terminal size. This leaves a window for SIGWINCH to be
78  * missed between here and where readline() enables libreadline's
79  * signal handler, but that's probably short enough to be ignored.
80  */
81 #ifdef HAVE_RL_RESET_SCREEN_SIZE
82  rl_reset_screen_size();
83 #endif
84 
85  /* Make current query_buf available to tab completion callback */
86  tab_completion_query_buf = query_buf;
87 
88  /* Enable SIGINT to longjmp to sigint_interrupt_jmp */
90 
91  /* On some platforms, readline is declared as readline(char *) */
92  result = readline((char *) prompt);
93 
94  /* Disable SIGINT again */
96 
97  /* Pure neatnik-ism */
99 
100  return result;
101  }
102 #endif
103 
104  fputs(prompt, stdout);
105  fflush(stdout);
106  return gets_fromFile(stdin);
107 }
108 
109 
110 /*
111  * Append the line to the history buffer, making sure there is a trailing '\n'
112  */
113 void
114 pg_append_history(const char *s, PQExpBuffer history_buf)
115 {
116 #ifdef USE_READLINE
117  if (useHistory && s)
118  {
119  appendPQExpBufferStr(history_buf, s);
120  if (!s[0] || s[strlen(s) - 1] != '\n')
121  appendPQExpBufferChar(history_buf, '\n');
122  }
123 #endif
124 }
125 
126 
127 /*
128  * Emit accumulated history entry to readline's history mechanism,
129  * then reset the buffer to empty.
130  *
131  * Note: we write nothing if history_buf is empty, so extra calls to this
132  * function don't hurt. There must have been at least one line added by
133  * pg_append_history before we'll do anything.
134  */
135 void
137 {
138 #ifdef USE_READLINE
139  static char *prev_hist = NULL;
140 
141  char *s = history_buf->data;
142  int i;
143 
144  /* Trim any trailing \n's (OK to scribble on history_buf) */
145  for (i = strlen(s) - 1; i >= 0 && s[i] == '\n'; i--)
146  ;
147  s[i + 1] = '\0';
148 
149  if (useHistory && s[0])
150  {
151  if (((pset.histcontrol & hctl_ignorespace) &&
152  s[0] == ' ') ||
154  prev_hist && strcmp(s, prev_hist) == 0))
155  {
156  /* Ignore this line as far as history is concerned */
157  }
158  else
159  {
160  /* Save each previous line for ignoredups processing */
161  if (prev_hist)
162  free(prev_hist);
163  prev_hist = pg_strdup(s);
164  /* And send it to readline */
165  add_history(s);
166  /* Count lines added to history for use later */
167  history_lines_added++;
168  }
169  }
170 
171  resetPQExpBuffer(history_buf);
172 #endif
173 }
174 
175 
176 /*
177  * gets_fromFile
178  *
179  * Gets a line of noninteractive input from a file (which could be stdin).
180  * The result is a malloc'd string, or NULL on EOF or input error.
181  *
182  * Caller *must* have set up sigint_interrupt_jmp before calling.
183  *
184  * Note: we re-use a static PQExpBuffer for each call. This is to avoid
185  * leaking memory if interrupted by SIGINT.
186  */
187 char *
189 {
190  static PQExpBuffer buffer = NULL;
191 
192  char line[1024];
193 
194  if (buffer == NULL) /* first time through? */
195  buffer = createPQExpBuffer();
196  else
197  resetPQExpBuffer(buffer);
198 
199  for (;;)
200  {
201  char *result;
202 
203  /* Enable SIGINT to longjmp to sigint_interrupt_jmp */
205 
206  /* Get some data */
207  result = fgets(line, sizeof(line), source);
208 
209  /* Disable SIGINT again */
210  sigint_interrupt_enabled = false;
211 
212  /* EOF or error? */
213  if (result == NULL)
214  {
215  if (ferror(source))
216  {
217  pg_log_error("could not read from input file: %m");
218  return NULL;
219  }
220  break;
221  }
222 
223  appendPQExpBufferStr(buffer, line);
224 
225  if (PQExpBufferBroken(buffer))
226  {
227  pg_log_error("out of memory");
228  return NULL;
229  }
230 
231  /* EOL? */
232  if (buffer->len > 0 && buffer->data[buffer->len - 1] == '\n')
233  {
234  buffer->data[buffer->len - 1] = '\0';
235  return pg_strdup(buffer->data);
236  }
237  }
238 
239  if (buffer->len > 0) /* EOF after reading some bufferload(s) */
240  return pg_strdup(buffer->data);
241 
242  /* EOF, so return null */
243  return NULL;
244 }
245 
246 
247 #ifdef USE_READLINE
248 
249 /*
250  * Macros to iterate over each element of the history list in order
251  *
252  * You would think this would be simple enough, but in its inimitable fashion
253  * libedit has managed to break it: in libreadline we must use next_history()
254  * to go from oldest to newest, but in libedit we must use previous_history().
255  * To detect what to do, we make a trial call of previous_history(): if it
256  * fails, then either next_history() is what to use, or there's zero or one
257  * history entry so that it doesn't matter which direction we go.
258  *
259  * In case that wasn't disgusting enough: the code below is not as obvious as
260  * it might appear. In some libedit releases history_set_pos(0) fails until
261  * at least one add_history() call has been done. This is not an issue for
262  * printHistory() or encode_history(), which cannot be invoked before that has
263  * happened. In decode_history(), that's not so, and what actually happens is
264  * that we are sitting on the newest entry to start with, previous_history()
265  * fails, and we iterate over all the entries using next_history(). So the
266  * decode_history() loop iterates over the entries in the wrong order when
267  * using such a libedit release, and if there were another attempt to use
268  * BEGIN_ITERATE_HISTORY() before some add_history() call had happened, it
269  * wouldn't work. Fortunately we don't care about either of those things.
270  *
271  * Usage pattern is:
272  *
273  * BEGIN_ITERATE_HISTORY(varname);
274  * {
275  * loop body referencing varname->line;
276  * }
277  * END_ITERATE_HISTORY();
278  */
279 #define BEGIN_ITERATE_HISTORY(VARNAME) \
280  do { \
281  HIST_ENTRY *VARNAME; \
282  bool use_prev_; \
283  \
284  history_set_pos(0); \
285  use_prev_ = (previous_history() != NULL); \
286  history_set_pos(0); \
287  for (VARNAME = current_history(); VARNAME != NULL; \
288  VARNAME = use_prev_ ? previous_history() : next_history()) \
289  { \
290  (void) 0
291 
292 #define END_ITERATE_HISTORY() \
293  } \
294  } while(0)
295 
296 
297 /*
298  * Convert newlines to NL_IN_HISTORY for safe saving in readline history file
299  */
300 static void
301 encode_history(void)
302 {
303  BEGIN_ITERATE_HISTORY(cur_hist);
304  {
305  char *cur_ptr;
306 
307  /* some platforms declare HIST_ENTRY.line as const char * */
308  for (cur_ptr = (char *) cur_hist->line; *cur_ptr; cur_ptr++)
309  {
310  if (*cur_ptr == '\n')
311  *cur_ptr = NL_IN_HISTORY;
312  }
313  }
314  END_ITERATE_HISTORY();
315 }
316 
317 /*
318  * Reverse the above encoding
319  */
320 static void
321 decode_history(void)
322 {
323  BEGIN_ITERATE_HISTORY(cur_hist);
324  {
325  char *cur_ptr;
326 
327  /* some platforms declare HIST_ENTRY.line as const char * */
328  for (cur_ptr = (char *) cur_hist->line; *cur_ptr; cur_ptr++)
329  {
330  if (*cur_ptr == NL_IN_HISTORY)
331  *cur_ptr = '\n';
332  }
333  }
334  END_ITERATE_HISTORY();
335 }
336 #endif /* USE_READLINE */
337 
338 
339 /*
340  * Put any startup stuff related to input in here. It's good to maintain
341  * abstraction this way.
342  *
343  * The only "flag" right now is 1 for use readline & history.
344  */
345 void
346 initializeInput(int flags)
347 {
348 #ifdef USE_READLINE
349  if (flags & 1)
350  {
351  const char *histfile;
352  char home[MAXPGPATH];
353 
354  useReadline = true;
355 
356  /* set appropriate values for Readline's global variables */
358 
359 #ifdef HAVE_RL_VARIABLE_BIND
360  /* set comment-begin to a useful value for SQL */
361  (void) rl_variable_bind("comment-begin", "-- ");
362 #endif
363 
364  /* this reads ~/.inputrc, so do it after rl_variable_bind */
365  rl_initialize();
366 
367  useHistory = true;
368  using_history();
369  history_lines_added = 0;
370 
371  histfile = GetVariable(pset.vars, "HISTFILE");
372 
373  if (histfile == NULL)
374  {
375  char *envhist;
376 
377  envhist = getenv("PSQL_HISTORY");
378  if (envhist != NULL && strlen(envhist) > 0)
379  histfile = envhist;
380  }
381 
382  if (histfile == NULL)
383  {
384  if (get_home_path(home))
385  psql_history = psprintf("%s/%s", home, PSQLHISTORY);
386  }
387  else
388  {
389  psql_history = pg_strdup(histfile);
390  expand_tilde(&psql_history);
391  }
392 
393  if (psql_history)
394  {
395  read_history(psql_history);
396  decode_history();
397  }
398  }
399 #endif
400 
401  atexit(finishInput);
402 }
403 
404 
405 /*
406  * This function saves the readline history when psql exits.
407  *
408  * fname: pathname of history file. (Should really be "const char *",
409  * but some ancient versions of readline omit the const-decoration.)
410  *
411  * max_lines: if >= 0, limit history file to that many entries.
412  */
413 #ifdef USE_READLINE
414 static bool
415 saveHistory(char *fname, int max_lines)
416 {
417  int errnum;
418 
419  /*
420  * Suppressing the write attempt when HISTFILE is set to /dev/null may
421  * look like a negligible optimization, but it's necessary on e.g. macOS,
422  * where write_history will fail because it tries to chmod the target
423  * file.
424  */
425  if (strcmp(fname, DEVNULL) != 0)
426  {
427  /*
428  * Encode \n, since otherwise readline will reload multiline history
429  * entries as separate lines. (libedit doesn't really need this, but
430  * we do it anyway since it's too hard to tell which implementation we
431  * are using.)
432  */
433  encode_history();
434 
435  /*
436  * On newer versions of libreadline, truncate the history file as
437  * needed and then append what we've added. This avoids overwriting
438  * history from other concurrent sessions (although there are still
439  * race conditions when two sessions exit at about the same time). If
440  * we don't have those functions, fall back to write_history().
441  */
442 #if defined(HAVE_HISTORY_TRUNCATE_FILE) && defined(HAVE_APPEND_HISTORY)
443  {
444  int nlines;
445  int fd;
446 
447  /* truncate previous entries if needed */
448  if (max_lines >= 0)
449  {
450  nlines = Max(max_lines - history_lines_added, 0);
451  (void) history_truncate_file(fname, nlines);
452  }
453  /* append_history fails if file doesn't already exist :-( */
454  fd = open(fname, O_CREAT | O_WRONLY | PG_BINARY, 0600);
455  if (fd >= 0)
456  close(fd);
457  /* append the appropriate number of lines */
458  if (max_lines >= 0)
459  nlines = Min(max_lines, history_lines_added);
460  else
461  nlines = history_lines_added;
462  errnum = append_history(nlines, fname);
463  if (errnum == 0)
464  return true;
465  }
466 #else /* don't have append support */
467  {
468  /* truncate what we have ... */
469  if (max_lines >= 0)
470  stifle_history(max_lines);
471  /* ... and overwrite file. Tough luck for concurrent sessions. */
472  errnum = write_history(fname);
473  if (errnum == 0)
474  return true;
475  }
476 #endif
477 
478  pg_log_error("could not save history to file \"%s\": %m", fname);
479  }
480  return false;
481 }
482 #endif
483 
484 
485 
486 /*
487  * Print history to the specified file, or to the console if fname is NULL
488  * (psql \s command)
489  *
490  * We used to use saveHistory() for this purpose, but that doesn't permit
491  * use of a pager; moreover libedit's implementation behaves incompatibly
492  * (preferring to encode its output) and may fail outright when the target
493  * file is specified as /dev/tty.
494  */
495 bool
496 printHistory(const char *fname, unsigned short int pager)
497 {
498 #ifdef USE_READLINE
499  FILE *output;
500  bool is_pager;
501 
502  if (!useHistory)
503  return false;
504 
505  if (fname == NULL)
506  {
507  /* use pager, if enabled, when printing to console */
508  output = PageOutput(INT_MAX, pager ? &(pset.popt.topt) : NULL);
509  is_pager = true;
510  }
511  else
512  {
513  output = fopen(fname, "w");
514  if (output == NULL)
515  {
516  pg_log_error("could not save history to file \"%s\": %m", fname);
517  return false;
518  }
519  is_pager = false;
520  }
521 
522  BEGIN_ITERATE_HISTORY(cur_hist);
523  {
524  fprintf(output, "%s\n", cur_hist->line);
525  }
526  END_ITERATE_HISTORY();
527 
528  if (is_pager)
530  else
531  fclose(output);
532 
533  return true;
534 #else
535  pg_log_error("history is not supported by this installation");
536  return false;
537 #endif
538 }
539 
540 
541 static void
543 {
544 #ifdef USE_READLINE
545  if (useHistory && psql_history)
546  {
547  (void) saveHistory(psql_history, pset.histsize);
548  free(psql_history);
549  psql_history = NULL;
550  }
551 #endif
552 }
void expand_tilde(char **filename)
Definition: common.c:2322
volatile bool sigint_interrupt_enabled
Definition: common.c:248
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#define Max(x, y)
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Definition: input.c:496
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Definition: input.c:67
static void finishInput(void)
Definition: input.c:542
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@ hctl_ignorespace
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