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fe-misc.c
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1 /*-------------------------------------------------------------------------
2  *
3  * FILE
4  * fe-misc.c
5  *
6  * DESCRIPTION
7  * miscellaneous useful functions
8  *
9  * The communication routines here are analogous to the ones in
10  * backend/libpq/pqcomm.c and backend/libpq/pqformat.c, but operate
11  * in the considerably different environment of the frontend libpq.
12  * In particular, we work with a bare nonblock-mode socket, rather than
13  * a stdio stream, so that we can avoid unwanted blocking of the application.
14  *
15  * XXX: MOVE DEBUG PRINTOUT TO HIGHER LEVEL. As is, block and restart
16  * will cause repeat printouts.
17  *
18  * We must speak the same transmitted data representations as the backend
19  * routines.
20  *
21  *
22  * Portions Copyright (c) 1996-2019, PostgreSQL Global Development Group
23  * Portions Copyright (c) 1994, Regents of the University of California
24  *
25  * IDENTIFICATION
26  * src/interfaces/libpq/fe-misc.c
27  *
28  *-------------------------------------------------------------------------
29  */
30 
31 #include "postgres_fe.h"
32 
33 #include <signal.h>
34 #include <time.h>
35 
36 #ifdef WIN32
37 #include "win32.h"
38 #else
39 #include <unistd.h>
40 #include <sys/time.h>
41 #endif
42 
43 #ifdef HAVE_POLL_H
44 #include <poll.h>
45 #endif
46 #ifdef HAVE_SYS_SELECT_H
47 #include <sys/select.h>
48 #endif
49 
50 #include "libpq-fe.h"
51 #include "libpq-int.h"
52 #include "mb/pg_wchar.h"
53 #include "port/pg_bswap.h"
54 #include "pg_config_paths.h"
55 
56 
57 static int pqPutMsgBytes(const void *buf, size_t len, PGconn *conn);
58 static int pqSendSome(PGconn *conn, int len);
59 static int pqSocketCheck(PGconn *conn, int forRead, int forWrite,
60  time_t end_time);
61 static int pqSocketPoll(int sock, int forRead, int forWrite, time_t end_time);
62 
63 /*
64  * PQlibVersion: return the libpq version number
65  */
66 int
68 {
69  return PG_VERSION_NUM;
70 }
71 
72 /*
73  * fputnbytes: print exactly N bytes to a file
74  *
75  * We avoid using %.*s here because it can misbehave if the data
76  * is not valid in what libc thinks is the prevailing encoding.
77  */
78 static void
79 fputnbytes(FILE *f, const char *str, size_t n)
80 {
81  while (n-- > 0)
82  fputc(*str++, f);
83 }
84 
85 
86 /*
87  * pqGetc: get 1 character from the connection
88  *
89  * All these routines return 0 on success, EOF on error.
90  * Note that for the Get routines, EOF only means there is not enough
91  * data in the buffer, not that there is necessarily a hard error.
92  */
93 int
94 pqGetc(char *result, PGconn *conn)
95 {
96  if (conn->inCursor >= conn->inEnd)
97  return EOF;
98 
99  *result = conn->inBuffer[conn->inCursor++];
100 
101  if (conn->Pfdebug)
102  fprintf(conn->Pfdebug, "From backend> %c\n", *result);
103 
104  return 0;
105 }
106 
107 
108 /*
109  * pqPutc: write 1 char to the current message
110  */
111 int
113 {
114  if (pqPutMsgBytes(&c, 1, conn))
115  return EOF;
116 
117  if (conn->Pfdebug)
118  fprintf(conn->Pfdebug, "To backend> %c\n", c);
119 
120  return 0;
121 }
122 
123 
124 /*
125  * pqGets[_append]:
126  * get a null-terminated string from the connection,
127  * and store it in an expansible PQExpBuffer.
128  * If we run out of memory, all of the string is still read,
129  * but the excess characters are silently discarded.
130  */
131 static int
133 {
134  /* Copy conn data to locals for faster search loop */
135  char *inBuffer = conn->inBuffer;
136  int inCursor = conn->inCursor;
137  int inEnd = conn->inEnd;
138  int slen;
139 
140  while (inCursor < inEnd && inBuffer[inCursor])
141  inCursor++;
142 
143  if (inCursor >= inEnd)
144  return EOF;
145 
146  slen = inCursor - conn->inCursor;
147 
148  if (resetbuffer)
149  resetPQExpBuffer(buf);
150 
151  appendBinaryPQExpBuffer(buf, inBuffer + conn->inCursor, slen);
152 
153  conn->inCursor = ++inCursor;
154 
155  if (conn->Pfdebug)
156  fprintf(conn->Pfdebug, "From backend> \"%s\"\n",
157  buf->data);
158 
159  return 0;
160 }
161 
162 int
164 {
165  return pqGets_internal(buf, conn, true);
166 }
167 
168 int
170 {
171  return pqGets_internal(buf, conn, false);
172 }
173 
174 
175 /*
176  * pqPuts: write a null-terminated string to the current message
177  */
178 int
179 pqPuts(const char *s, PGconn *conn)
180 {
181  if (pqPutMsgBytes(s, strlen(s) + 1, conn))
182  return EOF;
183 
184  if (conn->Pfdebug)
185  fprintf(conn->Pfdebug, "To backend> \"%s\"\n", s);
186 
187  return 0;
188 }
189 
190 /*
191  * pqGetnchar:
192  * get a string of exactly len bytes in buffer s, no null termination
193  */
194 int
195 pqGetnchar(char *s, size_t len, PGconn *conn)
196 {
197  if (len > (size_t) (conn->inEnd - conn->inCursor))
198  return EOF;
199 
200  memcpy(s, conn->inBuffer + conn->inCursor, len);
201  /* no terminating null */
202 
203  conn->inCursor += len;
204 
205  if (conn->Pfdebug)
206  {
207  fprintf(conn->Pfdebug, "From backend (%lu)> ", (unsigned long) len);
208  fputnbytes(conn->Pfdebug, s, len);
209  fprintf(conn->Pfdebug, "\n");
210  }
211 
212  return 0;
213 }
214 
215 /*
216  * pqSkipnchar:
217  * skip over len bytes in input buffer.
218  *
219  * Note: this is primarily useful for its debug output, which should
220  * be exactly the same as for pqGetnchar. We assume the data in question
221  * will actually be used, but just isn't getting copied anywhere as yet.
222  */
223 int
224 pqSkipnchar(size_t len, PGconn *conn)
225 {
226  if (len > (size_t) (conn->inEnd - conn->inCursor))
227  return EOF;
228 
229  if (conn->Pfdebug)
230  {
231  fprintf(conn->Pfdebug, "From backend (%lu)> ", (unsigned long) len);
232  fputnbytes(conn->Pfdebug, conn->inBuffer + conn->inCursor, len);
233  fprintf(conn->Pfdebug, "\n");
234  }
235 
236  conn->inCursor += len;
237 
238  return 0;
239 }
240 
241 /*
242  * pqPutnchar:
243  * write exactly len bytes to the current message
244  */
245 int
246 pqPutnchar(const char *s, size_t len, PGconn *conn)
247 {
248  if (pqPutMsgBytes(s, len, conn))
249  return EOF;
250 
251  if (conn->Pfdebug)
252  {
253  fprintf(conn->Pfdebug, "To backend> ");
254  fputnbytes(conn->Pfdebug, s, len);
255  fprintf(conn->Pfdebug, "\n");
256  }
257 
258  return 0;
259 }
260 
261 /*
262  * pqGetInt
263  * read a 2 or 4 byte integer and convert from network byte order
264  * to local byte order
265  */
266 int
267 pqGetInt(int *result, size_t bytes, PGconn *conn)
268 {
269  uint16 tmp2;
270  uint32 tmp4;
271 
272  switch (bytes)
273  {
274  case 2:
275  if (conn->inCursor + 2 > conn->inEnd)
276  return EOF;
277  memcpy(&tmp2, conn->inBuffer + conn->inCursor, 2);
278  conn->inCursor += 2;
279  *result = (int) pg_ntoh16(tmp2);
280  break;
281  case 4:
282  if (conn->inCursor + 4 > conn->inEnd)
283  return EOF;
284  memcpy(&tmp4, conn->inBuffer + conn->inCursor, 4);
285  conn->inCursor += 4;
286  *result = (int) pg_ntoh32(tmp4);
287  break;
288  default:
290  "integer of size %lu not supported by pqGetInt",
291  (unsigned long) bytes);
292  return EOF;
293  }
294 
295  if (conn->Pfdebug)
296  fprintf(conn->Pfdebug, "From backend (#%lu)> %d\n", (unsigned long) bytes, *result);
297 
298  return 0;
299 }
300 
301 /*
302  * pqPutInt
303  * write an integer of 2 or 4 bytes, converting from host byte order
304  * to network byte order.
305  */
306 int
308 {
309  uint16 tmp2;
310  uint32 tmp4;
311 
312  switch (bytes)
313  {
314  case 2:
315  tmp2 = pg_hton16((uint16) value);
316  if (pqPutMsgBytes((const char *) &tmp2, 2, conn))
317  return EOF;
318  break;
319  case 4:
320  tmp4 = pg_hton32((uint32) value);
321  if (pqPutMsgBytes((const char *) &tmp4, 4, conn))
322  return EOF;
323  break;
324  default:
326  "integer of size %lu not supported by pqPutInt",
327  (unsigned long) bytes);
328  return EOF;
329  }
330 
331  if (conn->Pfdebug)
332  fprintf(conn->Pfdebug, "To backend (%lu#)> %d\n", (unsigned long) bytes, value);
333 
334  return 0;
335 }
336 
337 /*
338  * Make sure conn's output buffer can hold bytes_needed bytes (caller must
339  * include already-stored data into the value!)
340  *
341  * Returns 0 on success, EOF if failed to enlarge buffer
342  */
343 int
344 pqCheckOutBufferSpace(size_t bytes_needed, PGconn *conn)
345 {
346  int newsize = conn->outBufSize;
347  char *newbuf;
348 
349  /* Quick exit if we have enough space */
350  if (bytes_needed <= (size_t) newsize)
351  return 0;
352 
353  /*
354  * If we need to enlarge the buffer, we first try to double it in size; if
355  * that doesn't work, enlarge in multiples of 8K. This avoids thrashing
356  * the malloc pool by repeated small enlargements.
357  *
358  * Note: tests for newsize > 0 are to catch integer overflow.
359  */
360  do
361  {
362  newsize *= 2;
363  } while (newsize > 0 && bytes_needed > (size_t) newsize);
364 
365  if (newsize > 0 && bytes_needed <= (size_t) newsize)
366  {
367  newbuf = realloc(conn->outBuffer, newsize);
368  if (newbuf)
369  {
370  /* realloc succeeded */
371  conn->outBuffer = newbuf;
372  conn->outBufSize = newsize;
373  return 0;
374  }
375  }
376 
377  newsize = conn->outBufSize;
378  do
379  {
380  newsize += 8192;
381  } while (newsize > 0 && bytes_needed > (size_t) newsize);
382 
383  if (newsize > 0 && bytes_needed <= (size_t) newsize)
384  {
385  newbuf = realloc(conn->outBuffer, newsize);
386  if (newbuf)
387  {
388  /* realloc succeeded */
389  conn->outBuffer = newbuf;
390  conn->outBufSize = newsize;
391  return 0;
392  }
393  }
394 
395  /* realloc failed. Probably out of memory */
397  "cannot allocate memory for output buffer\n");
398  return EOF;
399 }
400 
401 /*
402  * Make sure conn's input buffer can hold bytes_needed bytes (caller must
403  * include already-stored data into the value!)
404  *
405  * Returns 0 on success, EOF if failed to enlarge buffer
406  */
407 int
408 pqCheckInBufferSpace(size_t bytes_needed, PGconn *conn)
409 {
410  int newsize = conn->inBufSize;
411  char *newbuf;
412 
413  /* Quick exit if we have enough space */
414  if (bytes_needed <= (size_t) newsize)
415  return 0;
416 
417  /*
418  * Before concluding that we need to enlarge the buffer, left-justify
419  * whatever is in it and recheck. The caller's value of bytes_needed
420  * includes any data to the left of inStart, but we can delete that in
421  * preference to enlarging the buffer. It's slightly ugly to have this
422  * function do this, but it's better than making callers worry about it.
423  */
424  bytes_needed -= conn->inStart;
425 
426  if (conn->inStart < conn->inEnd)
427  {
428  if (conn->inStart > 0)
429  {
430  memmove(conn->inBuffer, conn->inBuffer + conn->inStart,
431  conn->inEnd - conn->inStart);
432  conn->inEnd -= conn->inStart;
433  conn->inCursor -= conn->inStart;
434  conn->inStart = 0;
435  }
436  }
437  else
438  {
439  /* buffer is logically empty, reset it */
440  conn->inStart = conn->inCursor = conn->inEnd = 0;
441  }
442 
443  /* Recheck whether we have enough space */
444  if (bytes_needed <= (size_t) newsize)
445  return 0;
446 
447  /*
448  * If we need to enlarge the buffer, we first try to double it in size; if
449  * that doesn't work, enlarge in multiples of 8K. This avoids thrashing
450  * the malloc pool by repeated small enlargements.
451  *
452  * Note: tests for newsize > 0 are to catch integer overflow.
453  */
454  do
455  {
456  newsize *= 2;
457  } while (newsize > 0 && bytes_needed > (size_t) newsize);
458 
459  if (newsize > 0 && bytes_needed <= (size_t) newsize)
460  {
461  newbuf = realloc(conn->inBuffer, newsize);
462  if (newbuf)
463  {
464  /* realloc succeeded */
465  conn->inBuffer = newbuf;
466  conn->inBufSize = newsize;
467  return 0;
468  }
469  }
470 
471  newsize = conn->inBufSize;
472  do
473  {
474  newsize += 8192;
475  } while (newsize > 0 && bytes_needed > (size_t) newsize);
476 
477  if (newsize > 0 && bytes_needed <= (size_t) newsize)
478  {
479  newbuf = realloc(conn->inBuffer, newsize);
480  if (newbuf)
481  {
482  /* realloc succeeded */
483  conn->inBuffer = newbuf;
484  conn->inBufSize = newsize;
485  return 0;
486  }
487  }
488 
489  /* realloc failed. Probably out of memory */
491  "cannot allocate memory for input buffer\n");
492  return EOF;
493 }
494 
495 /*
496  * pqPutMsgStart: begin construction of a message to the server
497  *
498  * msg_type is the message type byte, or 0 for a message without type byte
499  * (only startup messages have no type byte)
500  *
501  * force_len forces the message to have a length word; otherwise, we add
502  * a length word if protocol 3.
503  *
504  * Returns 0 on success, EOF on error
505  *
506  * The idea here is that we construct the message in conn->outBuffer,
507  * beginning just past any data already in outBuffer (ie, at
508  * outBuffer+outCount). We enlarge the buffer as needed to hold the message.
509  * When the message is complete, we fill in the length word (if needed) and
510  * then advance outCount past the message, making it eligible to send.
511  *
512  * The state variable conn->outMsgStart points to the incomplete message's
513  * length word: it is either outCount or outCount+1 depending on whether
514  * there is a type byte. If we are sending a message without length word
515  * (pre protocol 3.0 only), then outMsgStart is -1. The state variable
516  * conn->outMsgEnd is the end of the data collected so far.
517  */
518 int
519 pqPutMsgStart(char msg_type, bool force_len, PGconn *conn)
520 {
521  int lenPos;
522  int endPos;
523 
524  /* allow room for message type byte */
525  if (msg_type)
526  endPos = conn->outCount + 1;
527  else
528  endPos = conn->outCount;
529 
530  /* do we want a length word? */
531  if (force_len || PG_PROTOCOL_MAJOR(conn->pversion) >= 3)
532  {
533  lenPos = endPos;
534  /* allow room for message length */
535  endPos += 4;
536  }
537  else
538  lenPos = -1;
539 
540  /* make sure there is room for message header */
541  if (pqCheckOutBufferSpace(endPos, conn))
542  return EOF;
543  /* okay, save the message type byte if any */
544  if (msg_type)
545  conn->outBuffer[conn->outCount] = msg_type;
546  /* set up the message pointers */
547  conn->outMsgStart = lenPos;
548  conn->outMsgEnd = endPos;
549  /* length word, if needed, will be filled in by pqPutMsgEnd */
550 
551  if (conn->Pfdebug)
552  fprintf(conn->Pfdebug, "To backend> Msg %c\n",
553  msg_type ? msg_type : ' ');
554 
555  return 0;
556 }
557 
558 /*
559  * pqPutMsgBytes: add bytes to a partially-constructed message
560  *
561  * Returns 0 on success, EOF on error
562  */
563 static int
564 pqPutMsgBytes(const void *buf, size_t len, PGconn *conn)
565 {
566  /* make sure there is room for it */
567  if (pqCheckOutBufferSpace(conn->outMsgEnd + len, conn))
568  return EOF;
569  /* okay, save the data */
570  memcpy(conn->outBuffer + conn->outMsgEnd, buf, len);
571  conn->outMsgEnd += len;
572  /* no Pfdebug call here, caller should do it */
573  return 0;
574 }
575 
576 /*
577  * pqPutMsgEnd: finish constructing a message and possibly send it
578  *
579  * Returns 0 on success, EOF on error
580  *
581  * We don't actually send anything here unless we've accumulated at least
582  * 8K worth of data (the typical size of a pipe buffer on Unix systems).
583  * This avoids sending small partial packets. The caller must use pqFlush
584  * when it's important to flush all the data out to the server.
585  */
586 int
588 {
589  if (conn->Pfdebug)
590  fprintf(conn->Pfdebug, "To backend> Msg complete, length %u\n",
591  conn->outMsgEnd - conn->outCount);
592 
593  /* Fill in length word if needed */
594  if (conn->outMsgStart >= 0)
595  {
596  uint32 msgLen = conn->outMsgEnd - conn->outMsgStart;
597 
598  msgLen = pg_hton32(msgLen);
599  memcpy(conn->outBuffer + conn->outMsgStart, &msgLen, 4);
600  }
601 
602  /* Make message eligible to send */
603  conn->outCount = conn->outMsgEnd;
604 
605  if (conn->outCount >= 8192)
606  {
607  int toSend = conn->outCount - (conn->outCount % 8192);
608 
609  if (pqSendSome(conn, toSend) < 0)
610  return EOF;
611  /* in nonblock mode, don't complain if unable to send it all */
612  }
613 
614  return 0;
615 }
616 
617 /* ----------
618  * pqReadData: read more data, if any is available
619  * Possible return values:
620  * 1: successfully loaded at least one more byte
621  * 0: no data is presently available, but no error detected
622  * -1: error detected (including EOF = connection closure);
623  * conn->errorMessage set
624  * NOTE: callers must not assume that pointers or indexes into conn->inBuffer
625  * remain valid across this call!
626  * ----------
627  */
628 int
630 {
631  int someread = 0;
632  int nread;
633 
634  if (conn->sock == PGINVALID_SOCKET)
635  {
637  libpq_gettext("connection not open\n"));
638  return -1;
639  }
640 
641  /* Left-justify any data in the buffer to make room */
642  if (conn->inStart < conn->inEnd)
643  {
644  if (conn->inStart > 0)
645  {
646  memmove(conn->inBuffer, conn->inBuffer + conn->inStart,
647  conn->inEnd - conn->inStart);
648  conn->inEnd -= conn->inStart;
649  conn->inCursor -= conn->inStart;
650  conn->inStart = 0;
651  }
652  }
653  else
654  {
655  /* buffer is logically empty, reset it */
656  conn->inStart = conn->inCursor = conn->inEnd = 0;
657  }
658 
659  /*
660  * If the buffer is fairly full, enlarge it. We need to be able to enlarge
661  * the buffer in case a single message exceeds the initial buffer size. We
662  * enlarge before filling the buffer entirely so as to avoid asking the
663  * kernel for a partial packet. The magic constant here should be large
664  * enough for a TCP packet or Unix pipe bufferload. 8K is the usual pipe
665  * buffer size, so...
666  */
667  if (conn->inBufSize - conn->inEnd < 8192)
668  {
669  if (pqCheckInBufferSpace(conn->inEnd + (size_t) 8192, conn))
670  {
671  /*
672  * We don't insist that the enlarge worked, but we need some room
673  */
674  if (conn->inBufSize - conn->inEnd < 100)
675  return -1; /* errorMessage already set */
676  }
677  }
678 
679  /* OK, try to read some data */
680 retry3:
681  nread = pqsecure_read(conn, conn->inBuffer + conn->inEnd,
682  conn->inBufSize - conn->inEnd);
683  if (nread < 0)
684  {
685  if (SOCK_ERRNO == EINTR)
686  goto retry3;
687  /* Some systems return EAGAIN/EWOULDBLOCK for no data */
688 #ifdef EAGAIN
689  if (SOCK_ERRNO == EAGAIN)
690  return someread;
691 #endif
692 #if defined(EWOULDBLOCK) && (!defined(EAGAIN) || (EWOULDBLOCK != EAGAIN))
693  if (SOCK_ERRNO == EWOULDBLOCK)
694  return someread;
695 #endif
696  /* We might get ECONNRESET here if using TCP and backend died */
697 #ifdef ECONNRESET
698  if (SOCK_ERRNO == ECONNRESET)
699  goto definitelyFailed;
700 #endif
701  /* pqsecure_read set the error message for us */
702  return -1;
703  }
704  if (nread > 0)
705  {
706  conn->inEnd += nread;
707 
708  /*
709  * Hack to deal with the fact that some kernels will only give us back
710  * 1 packet per recv() call, even if we asked for more and there is
711  * more available. If it looks like we are reading a long message,
712  * loop back to recv() again immediately, until we run out of data or
713  * buffer space. Without this, the block-and-restart behavior of
714  * libpq's higher levels leads to O(N^2) performance on long messages.
715  *
716  * Since we left-justified the data above, conn->inEnd gives the
717  * amount of data already read in the current message. We consider
718  * the message "long" once we have acquired 32k ...
719  */
720  if (conn->inEnd > 32768 &&
721  (conn->inBufSize - conn->inEnd) >= 8192)
722  {
723  someread = 1;
724  goto retry3;
725  }
726  return 1;
727  }
728 
729  if (someread)
730  return 1; /* got a zero read after successful tries */
731 
732  /*
733  * A return value of 0 could mean just that no data is now available, or
734  * it could mean EOF --- that is, the server has closed the connection.
735  * Since we have the socket in nonblock mode, the only way to tell the
736  * difference is to see if select() is saying that the file is ready.
737  * Grumble. Fortunately, we don't expect this path to be taken much,
738  * since in normal practice we should not be trying to read data unless
739  * the file selected for reading already.
740  *
741  * In SSL mode it's even worse: SSL_read() could say WANT_READ and then
742  * data could arrive before we make the pqReadReady() test, but the second
743  * SSL_read() could still say WANT_READ because the data received was not
744  * a complete SSL record. So we must play dumb and assume there is more
745  * data, relying on the SSL layer to detect true EOF.
746  */
747 
748 #ifdef USE_SSL
749  if (conn->ssl_in_use)
750  return 0;
751 #endif
752 
753  switch (pqReadReady(conn))
754  {
755  case 0:
756  /* definitely no data available */
757  return 0;
758  case 1:
759  /* ready for read */
760  break;
761  default:
762  /* we override pqReadReady's message with something more useful */
763  goto definitelyEOF;
764  }
765 
766  /*
767  * Still not sure that it's EOF, because some data could have just
768  * arrived.
769  */
770 retry4:
771  nread = pqsecure_read(conn, conn->inBuffer + conn->inEnd,
772  conn->inBufSize - conn->inEnd);
773  if (nread < 0)
774  {
775  if (SOCK_ERRNO == EINTR)
776  goto retry4;
777  /* Some systems return EAGAIN/EWOULDBLOCK for no data */
778 #ifdef EAGAIN
779  if (SOCK_ERRNO == EAGAIN)
780  return 0;
781 #endif
782 #if defined(EWOULDBLOCK) && (!defined(EAGAIN) || (EWOULDBLOCK != EAGAIN))
783  if (SOCK_ERRNO == EWOULDBLOCK)
784  return 0;
785 #endif
786  /* We might get ECONNRESET here if using TCP and backend died */
787 #ifdef ECONNRESET
788  if (SOCK_ERRNO == ECONNRESET)
789  goto definitelyFailed;
790 #endif
791  /* pqsecure_read set the error message for us */
792  return -1;
793  }
794  if (nread > 0)
795  {
796  conn->inEnd += nread;
797  return 1;
798  }
799 
800  /*
801  * OK, we are getting a zero read even though select() says ready. This
802  * means the connection has been closed. Cope.
803  */
804 definitelyEOF:
807  "server closed the connection unexpectedly\n"
808  "\tThis probably means the server terminated abnormally\n"
809  "\tbefore or while processing the request.\n"));
810 
811  /* Come here if lower-level code already set a suitable errorMessage */
812 definitelyFailed:
813  /* Do *not* drop any already-read data; caller still wants it */
814  pqDropConnection(conn, false);
815  conn->status = CONNECTION_BAD; /* No more connection to backend */
816  return -1;
817 }
818 
819 /*
820  * pqSendSome: send data waiting in the output buffer.
821  *
822  * len is how much to try to send (typically equal to outCount, but may
823  * be less).
824  *
825  * Return 0 on success, -1 on failure and 1 when not all data could be sent
826  * because the socket would block and the connection is non-blocking.
827  *
828  * Upon write failure, conn->write_failed is set and the error message is
829  * saved in conn->write_err_msg, but we clear the output buffer and return
830  * zero anyway; this is because callers should soldier on until it's possible
831  * to read from the server and check for an error message. write_err_msg
832  * should be reported only when we are unable to obtain a server error first.
833  * (Thus, a -1 result is returned only for an internal *read* failure.)
834  */
835 static int
837 {
838  char *ptr = conn->outBuffer;
839  int remaining = conn->outCount;
840  int result = 0;
841 
842  /*
843  * If we already had a write failure, we will never again try to send data
844  * on that connection. Even if the kernel would let us, we've probably
845  * lost message boundary sync with the server. conn->write_failed
846  * therefore persists until the connection is reset, and we just discard
847  * all data presented to be written.
848  */
849  if (conn->write_failed)
850  {
851  /* conn->write_err_msg should be set up already */
852  conn->outCount = 0;
853  return 0;
854  }
855 
856  if (conn->sock == PGINVALID_SOCKET)
857  {
859  libpq_gettext("connection not open\n"));
860  conn->write_failed = true;
861  /* Transfer error message to conn->write_err_msg, if possible */
862  /* (strdup failure is OK, we'll cope later) */
863  conn->write_err_msg = strdup(conn->errorMessage.data);
865  /* Discard queued data; no chance it'll ever be sent */
866  conn->outCount = 0;
867  return 0;
868  }
869 
870  /* while there's still data to send */
871  while (len > 0)
872  {
873  int sent;
874 
875 #ifndef WIN32
876  sent = pqsecure_write(conn, ptr, len);
877 #else
878 
879  /*
880  * Windows can fail on large sends, per KB article Q201213. The
881  * failure-point appears to be different in different versions of
882  * Windows, but 64k should always be safe.
883  */
884  sent = pqsecure_write(conn, ptr, Min(len, 65536));
885 #endif
886 
887  if (sent < 0)
888  {
889  /* Anything except EAGAIN/EWOULDBLOCK/EINTR is trouble */
890  switch (SOCK_ERRNO)
891  {
892 #ifdef EAGAIN
893  case EAGAIN:
894  break;
895 #endif
896 #if defined(EWOULDBLOCK) && (!defined(EAGAIN) || (EWOULDBLOCK != EAGAIN))
897  case EWOULDBLOCK:
898  break;
899 #endif
900  case EINTR:
901  continue;
902 
903  default:
904  /* pqsecure_write set the error message for us */
905  conn->write_failed = true;
906 
907  /*
908  * Transfer error message to conn->write_err_msg, if
909  * possible (strdup failure is OK, we'll cope later).
910  *
911  * Note: this assumes that pqsecure_write and its children
912  * will overwrite not append to conn->errorMessage. If
913  * that's ever changed, we could remember the length of
914  * conn->errorMessage at entry to this routine, and then
915  * save and delete just what was appended.
916  */
917  conn->write_err_msg = strdup(conn->errorMessage.data);
919 
920  /* Discard queued data; no chance it'll ever be sent */
921  conn->outCount = 0;
922  return 0;
923  }
924  }
925  else
926  {
927  ptr += sent;
928  len -= sent;
929  remaining -= sent;
930  }
931 
932  if (len > 0)
933  {
934  /*
935  * We didn't send it all, wait till we can send more.
936  *
937  * There are scenarios in which we can't send data because the
938  * communications channel is full, but we cannot expect the server
939  * to clear the channel eventually because it's blocked trying to
940  * send data to us. (This can happen when we are sending a large
941  * amount of COPY data, and the server has generated lots of
942  * NOTICE responses.) To avoid a deadlock situation, we must be
943  * prepared to accept and buffer incoming data before we try
944  * again. Furthermore, it is possible that such incoming data
945  * might not arrive until after we've gone to sleep. Therefore,
946  * we wait for either read ready or write ready.
947  *
948  * In non-blocking mode, we don't wait here directly, but return 1
949  * to indicate that data is still pending. The caller should wait
950  * for both read and write ready conditions, and call
951  * PQconsumeInput() on read ready, but just in case it doesn't, we
952  * call pqReadData() ourselves before returning. That's not
953  * enough if the data has not arrived yet, but it's the best we
954  * can do, and works pretty well in practice. (The documentation
955  * used to say that you only need to wait for write-ready, so
956  * there are still plenty of applications like that out there.)
957  *
958  * Note that errors here don't result in write_failed becoming
959  * set.
960  */
961  if (pqReadData(conn) < 0)
962  {
963  result = -1; /* error message already set up */
964  break;
965  }
966 
967  if (pqIsnonblocking(conn))
968  {
969  result = 1;
970  break;
971  }
972 
973  if (pqWait(true, true, conn))
974  {
975  result = -1;
976  break;
977  }
978  }
979  }
980 
981  /* shift the remaining contents of the buffer */
982  if (remaining > 0)
983  memmove(conn->outBuffer, ptr, remaining);
984  conn->outCount = remaining;
985 
986  return result;
987 }
988 
989 
990 /*
991  * pqFlush: send any data waiting in the output buffer
992  *
993  * Return 0 on success, -1 on failure and 1 when not all data could be sent
994  * because the socket would block and the connection is non-blocking.
995  * (See pqSendSome comments about how failure should be handled.)
996  */
997 int
999 {
1000  if (conn->Pfdebug)
1001  fflush(conn->Pfdebug);
1002 
1003  if (conn->outCount > 0)
1004  return pqSendSome(conn, conn->outCount);
1005 
1006  return 0;
1007 }
1008 
1009 
1010 /*
1011  * pqWait: wait until we can read or write the connection socket
1012  *
1013  * JAB: If SSL enabled and used and forRead, buffered bytes short-circuit the
1014  * call to select().
1015  *
1016  * We also stop waiting and return if the kernel flags an exception condition
1017  * on the socket. The actual error condition will be detected and reported
1018  * when the caller tries to read or write the socket.
1019  */
1020 int
1021 pqWait(int forRead, int forWrite, PGconn *conn)
1022 {
1023  return pqWaitTimed(forRead, forWrite, conn, (time_t) -1);
1024 }
1025 
1026 /*
1027  * pqWaitTimed: wait, but not past finish_time.
1028  *
1029  * finish_time = ((time_t) -1) disables the wait limit.
1030  *
1031  * Returns -1 on failure, 0 if the socket is readable/writable, 1 if it timed out.
1032  */
1033 int
1034 pqWaitTimed(int forRead, int forWrite, PGconn *conn, time_t finish_time)
1035 {
1036  int result;
1037 
1038  result = pqSocketCheck(conn, forRead, forWrite, finish_time);
1039 
1040  if (result < 0)
1041  return -1; /* errorMessage is already set */
1042 
1043  if (result == 0)
1044  {
1046  libpq_gettext("timeout expired\n"));
1047  return 1;
1048  }
1049 
1050  return 0;
1051 }
1052 
1053 /*
1054  * pqReadReady: is select() saying the file is ready to read?
1055  * Returns -1 on failure, 0 if not ready, 1 if ready.
1056  */
1057 int
1059 {
1060  return pqSocketCheck(conn, 1, 0, (time_t) 0);
1061 }
1062 
1063 /*
1064  * pqWriteReady: is select() saying the file is ready to write?
1065  * Returns -1 on failure, 0 if not ready, 1 if ready.
1066  */
1067 int
1069 {
1070  return pqSocketCheck(conn, 0, 1, (time_t) 0);
1071 }
1072 
1073 /*
1074  * Checks a socket, using poll or select, for data to be read, written,
1075  * or both. Returns >0 if one or more conditions are met, 0 if it timed
1076  * out, -1 if an error occurred.
1077  *
1078  * If SSL is in use, the SSL buffer is checked prior to checking the socket
1079  * for read data directly.
1080  */
1081 static int
1082 pqSocketCheck(PGconn *conn, int forRead, int forWrite, time_t end_time)
1083 {
1084  int result;
1085 
1086  if (!conn)
1087  return -1;
1088  if (conn->sock == PGINVALID_SOCKET)
1089  {
1091  libpq_gettext("invalid socket\n"));
1092  return -1;
1093  }
1094 
1095 #ifdef USE_SSL
1096  /* Check for SSL library buffering read bytes */
1097  if (forRead && conn->ssl_in_use && pgtls_read_pending(conn))
1098  {
1099  /* short-circuit the select */
1100  return 1;
1101  }
1102 #endif
1103 
1104  /* We will retry as long as we get EINTR */
1105  do
1106  result = pqSocketPoll(conn->sock, forRead, forWrite, end_time);
1107  while (result < 0 && SOCK_ERRNO == EINTR);
1108 
1109  if (result < 0)
1110  {
1111  char sebuf[PG_STRERROR_R_BUFLEN];
1112 
1114  libpq_gettext("select() failed: %s\n"),
1115  SOCK_STRERROR(SOCK_ERRNO, sebuf, sizeof(sebuf)));
1116  }
1117 
1118  return result;
1119 }
1120 
1121 
1122 /*
1123  * Check a file descriptor for read and/or write data, possibly waiting.
1124  * If neither forRead nor forWrite are set, immediately return a timeout
1125  * condition (without waiting). Return >0 if condition is met, 0
1126  * if a timeout occurred, -1 if an error or interrupt occurred.
1127  *
1128  * Timeout is infinite if end_time is -1. Timeout is immediate (no blocking)
1129  * if end_time is 0 (or indeed, any time before now).
1130  */
1131 static int
1132 pqSocketPoll(int sock, int forRead, int forWrite, time_t end_time)
1133 {
1134  /* We use poll(2) if available, otherwise select(2) */
1135 #ifdef HAVE_POLL
1136  struct pollfd input_fd;
1137  int timeout_ms;
1138 
1139  if (!forRead && !forWrite)
1140  return 0;
1141 
1142  input_fd.fd = sock;
1143  input_fd.events = POLLERR;
1144  input_fd.revents = 0;
1145 
1146  if (forRead)
1147  input_fd.events |= POLLIN;
1148  if (forWrite)
1149  input_fd.events |= POLLOUT;
1150 
1151  /* Compute appropriate timeout interval */
1152  if (end_time == ((time_t) -1))
1153  timeout_ms = -1;
1154  else
1155  {
1156  time_t now = time(NULL);
1157 
1158  if (end_time > now)
1159  timeout_ms = (end_time - now) * 1000;
1160  else
1161  timeout_ms = 0;
1162  }
1163 
1164  return poll(&input_fd, 1, timeout_ms);
1165 #else /* !HAVE_POLL */
1166 
1167  fd_set input_mask;
1168  fd_set output_mask;
1169  fd_set except_mask;
1170  struct timeval timeout;
1171  struct timeval *ptr_timeout;
1172 
1173  if (!forRead && !forWrite)
1174  return 0;
1175 
1176  FD_ZERO(&input_mask);
1177  FD_ZERO(&output_mask);
1178  FD_ZERO(&except_mask);
1179  if (forRead)
1180  FD_SET(sock, &input_mask);
1181 
1182  if (forWrite)
1183  FD_SET(sock, &output_mask);
1184  FD_SET(sock, &except_mask);
1185 
1186  /* Compute appropriate timeout interval */
1187  if (end_time == ((time_t) -1))
1188  ptr_timeout = NULL;
1189  else
1190  {
1191  time_t now = time(NULL);
1192 
1193  if (end_time > now)
1194  timeout.tv_sec = end_time - now;
1195  else
1196  timeout.tv_sec = 0;
1197  timeout.tv_usec = 0;
1198  ptr_timeout = &timeout;
1199  }
1200 
1201  return select(sock + 1, &input_mask, &output_mask,
1202  &except_mask, ptr_timeout);
1203 #endif /* HAVE_POLL */
1204 }
1205 
1206 
1207 /*
1208  * A couple of "miscellaneous" multibyte related functions. They used
1209  * to be in fe-print.c but that file is doomed.
1210  */
1211 
1212 /*
1213  * returns the byte length of the character beginning at s, using the
1214  * specified encoding.
1215  */
1216 int
1217 PQmblen(const char *s, int encoding)
1218 {
1219  return pg_encoding_mblen(encoding, s);
1220 }
1221 
1222 /*
1223  * returns the display length of the character beginning at s, using the
1224  * specified encoding.
1225  */
1226 int
1227 PQdsplen(const char *s, int encoding)
1228 {
1229  return pg_encoding_dsplen(encoding, s);
1230 }
1231 
1232 /*
1233  * Get encoding id from environment variable PGCLIENTENCODING.
1234  */
1235 int
1237 {
1238  char *str;
1239  int encoding = PG_SQL_ASCII;
1240 
1241  str = getenv("PGCLIENTENCODING");
1242  if (str && *str != '\0')
1243  {
1244  encoding = pg_char_to_encoding(str);
1245  if (encoding < 0)
1246  encoding = PG_SQL_ASCII;
1247  }
1248  return encoding;
1249 }
1250 
1251 
1252 #ifdef ENABLE_NLS
1253 
1254 static void
1255 libpq_binddomain()
1256 {
1257  static bool already_bound = false;
1258 
1259  if (!already_bound)
1260  {
1261  /* bindtextdomain() does not preserve errno */
1262 #ifdef WIN32
1263  int save_errno = GetLastError();
1264 #else
1265  int save_errno = errno;
1266 #endif
1267  const char *ldir;
1268 
1269  already_bound = true;
1270  /* No relocatable lookup here because the binary could be anywhere */
1271  ldir = getenv("PGLOCALEDIR");
1272  if (!ldir)
1273  ldir = LOCALEDIR;
1274  bindtextdomain(PG_TEXTDOMAIN("libpq"), ldir);
1275 #ifdef WIN32
1276  SetLastError(save_errno);
1277 #else
1278  errno = save_errno;
1279 #endif
1280  }
1281 }
1282 
1283 char *
1284 libpq_gettext(const char *msgid)
1285 {
1286  libpq_binddomain();
1287  return dgettext(PG_TEXTDOMAIN("libpq"), msgid);
1288 }
1289 
1290 char *
1291 libpq_ngettext(const char *msgid, const char *msgid_plural, unsigned long n)
1292 {
1293  libpq_binddomain();
1294  return dngettext(PG_TEXTDOMAIN("libpq"), msgid, msgid_plural, n);
1295 }
1296 
1297 #endif /* ENABLE_NLS */
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