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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) 1996-2024, 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/select.h>
41 #include <sys/time.h>
42 #endif
43 
44 #ifdef HAVE_POLL_H
45 #include <poll.h>
46 #endif
47 
48 #include "libpq-fe.h"
49 #include "libpq-int.h"
50 #include "mb/pg_wchar.h"
51 #include "pg_config_paths.h"
52 #include "port/pg_bswap.h"
53 
54 static int pqPutMsgBytes(const void *buf, size_t len, PGconn *conn);
55 static int pqSendSome(PGconn *conn, int len);
56 static int pqSocketCheck(PGconn *conn, int forRead, int forWrite,
58 
59 /*
60  * PQlibVersion: return the libpq version number
61  */
62 int
64 {
65  return PG_VERSION_NUM;
66 }
67 
68 
69 /*
70  * pqGetc: get 1 character from the connection
71  *
72  * All these routines return 0 on success, EOF on error.
73  * Note that for the Get routines, EOF only means there is not enough
74  * data in the buffer, not that there is necessarily a hard error.
75  */
76 int
77 pqGetc(char *result, PGconn *conn)
78 {
79  if (conn->inCursor >= conn->inEnd)
80  return EOF;
81 
82  *result = conn->inBuffer[conn->inCursor++];
83 
84  return 0;
85 }
86 
87 
88 /*
89  * pqPutc: write 1 char to the current message
90  */
91 int
93 {
94  if (pqPutMsgBytes(&c, 1, conn))
95  return EOF;
96 
97  return 0;
98 }
99 
100 
101 /*
102  * pqGets[_append]:
103  * get a null-terminated string from the connection,
104  * and store it in an expansible PQExpBuffer.
105  * If we run out of memory, all of the string is still read,
106  * but the excess characters are silently discarded.
107  */
108 static int
110 {
111  /* Copy conn data to locals for faster search loop */
112  char *inBuffer = conn->inBuffer;
113  int inCursor = conn->inCursor;
114  int inEnd = conn->inEnd;
115  int slen;
116 
117  while (inCursor < inEnd && inBuffer[inCursor])
118  inCursor++;
119 
120  if (inCursor >= inEnd)
121  return EOF;
122 
123  slen = inCursor - conn->inCursor;
124 
125  if (resetbuffer)
127 
128  appendBinaryPQExpBuffer(buf, inBuffer + conn->inCursor, slen);
129 
130  conn->inCursor = ++inCursor;
131 
132  return 0;
133 }
134 
135 int
137 {
138  return pqGets_internal(buf, conn, true);
139 }
140 
141 int
143 {
144  return pqGets_internal(buf, conn, false);
145 }
146 
147 
148 /*
149  * pqPuts: write a null-terminated string to the current message
150  */
151 int
152 pqPuts(const char *s, PGconn *conn)
153 {
154  if (pqPutMsgBytes(s, strlen(s) + 1, conn))
155  return EOF;
156 
157  return 0;
158 }
159 
160 /*
161  * pqGetnchar:
162  * get a string of exactly len bytes in buffer s, no null termination
163  */
164 int
165 pqGetnchar(char *s, size_t len, PGconn *conn)
166 {
167  if (len > (size_t) (conn->inEnd - conn->inCursor))
168  return EOF;
169 
170  memcpy(s, conn->inBuffer + conn->inCursor, len);
171  /* no terminating null */
172 
173  conn->inCursor += len;
174 
175  return 0;
176 }
177 
178 /*
179  * pqSkipnchar:
180  * skip over len bytes in input buffer.
181  *
182  * Note: this is primarily useful for its debug output, which should
183  * be exactly the same as for pqGetnchar. We assume the data in question
184  * will actually be used, but just isn't getting copied anywhere as yet.
185  */
186 int
188 {
189  if (len > (size_t) (conn->inEnd - conn->inCursor))
190  return EOF;
191 
192  conn->inCursor += len;
193 
194  return 0;
195 }
196 
197 /*
198  * pqPutnchar:
199  * write exactly len bytes to the current message
200  */
201 int
202 pqPutnchar(const char *s, size_t len, PGconn *conn)
203 {
204  if (pqPutMsgBytes(s, len, conn))
205  return EOF;
206 
207  return 0;
208 }
209 
210 /*
211  * pqGetInt
212  * read a 2 or 4 byte integer and convert from network byte order
213  * to local byte order
214  */
215 int
216 pqGetInt(int *result, size_t bytes, PGconn *conn)
217 {
218  uint16 tmp2;
219  uint32 tmp4;
220 
221  switch (bytes)
222  {
223  case 2:
224  if (conn->inCursor + 2 > conn->inEnd)
225  return EOF;
226  memcpy(&tmp2, conn->inBuffer + conn->inCursor, 2);
227  conn->inCursor += 2;
228  *result = (int) pg_ntoh16(tmp2);
229  break;
230  case 4:
231  if (conn->inCursor + 4 > conn->inEnd)
232  return EOF;
233  memcpy(&tmp4, conn->inBuffer + conn->inCursor, 4);
234  conn->inCursor += 4;
235  *result = (int) pg_ntoh32(tmp4);
236  break;
237  default:
239  "integer of size %lu not supported by pqGetInt",
240  (unsigned long) bytes);
241  return EOF;
242  }
243 
244  return 0;
245 }
246 
247 /*
248  * pqPutInt
249  * write an integer of 2 or 4 bytes, converting from host byte order
250  * to network byte order.
251  */
252 int
253 pqPutInt(int value, size_t bytes, PGconn *conn)
254 {
255  uint16 tmp2;
256  uint32 tmp4;
257 
258  switch (bytes)
259  {
260  case 2:
261  tmp2 = pg_hton16((uint16) value);
262  if (pqPutMsgBytes((const char *) &tmp2, 2, conn))
263  return EOF;
264  break;
265  case 4:
266  tmp4 = pg_hton32((uint32) value);
267  if (pqPutMsgBytes((const char *) &tmp4, 4, conn))
268  return EOF;
269  break;
270  default:
272  "integer of size %lu not supported by pqPutInt",
273  (unsigned long) bytes);
274  return EOF;
275  }
276 
277  return 0;
278 }
279 
280 /*
281  * Make sure conn's output buffer can hold bytes_needed bytes (caller must
282  * include already-stored data into the value!)
283  *
284  * Returns 0 on success, EOF if failed to enlarge buffer
285  */
286 int
287 pqCheckOutBufferSpace(size_t bytes_needed, PGconn *conn)
288 {
289  int newsize = conn->outBufSize;
290  char *newbuf;
291 
292  /* Quick exit if we have enough space */
293  if (bytes_needed <= (size_t) newsize)
294  return 0;
295 
296  /*
297  * If we need to enlarge the buffer, we first try to double it in size; if
298  * that doesn't work, enlarge in multiples of 8K. This avoids thrashing
299  * the malloc pool by repeated small enlargements.
300  *
301  * Note: tests for newsize > 0 are to catch integer overflow.
302  */
303  do
304  {
305  newsize *= 2;
306  } while (newsize > 0 && bytes_needed > (size_t) newsize);
307 
308  if (newsize > 0 && bytes_needed <= (size_t) newsize)
309  {
310  newbuf = realloc(conn->outBuffer, newsize);
311  if (newbuf)
312  {
313  /* realloc succeeded */
314  conn->outBuffer = newbuf;
315  conn->outBufSize = newsize;
316  return 0;
317  }
318  }
319 
320  newsize = conn->outBufSize;
321  do
322  {
323  newsize += 8192;
324  } while (newsize > 0 && bytes_needed > (size_t) newsize);
325 
326  if (newsize > 0 && bytes_needed <= (size_t) newsize)
327  {
328  newbuf = realloc(conn->outBuffer, newsize);
329  if (newbuf)
330  {
331  /* realloc succeeded */
332  conn->outBuffer = newbuf;
333  conn->outBufSize = newsize;
334  return 0;
335  }
336  }
337 
338  /* realloc failed. Probably out of memory */
340  "cannot allocate memory for output buffer\n");
341  return EOF;
342 }
343 
344 /*
345  * Make sure conn's input buffer can hold bytes_needed bytes (caller must
346  * include already-stored data into the value!)
347  *
348  * Returns 0 on success, EOF if failed to enlarge buffer
349  */
350 int
351 pqCheckInBufferSpace(size_t bytes_needed, PGconn *conn)
352 {
353  int newsize = conn->inBufSize;
354  char *newbuf;
355 
356  /* Quick exit if we have enough space */
357  if (bytes_needed <= (size_t) newsize)
358  return 0;
359 
360  /*
361  * Before concluding that we need to enlarge the buffer, left-justify
362  * whatever is in it and recheck. The caller's value of bytes_needed
363  * includes any data to the left of inStart, but we can delete that in
364  * preference to enlarging the buffer. It's slightly ugly to have this
365  * function do this, but it's better than making callers worry about it.
366  */
367  bytes_needed -= conn->inStart;
368 
369  if (conn->inStart < conn->inEnd)
370  {
371  if (conn->inStart > 0)
372  {
373  memmove(conn->inBuffer, conn->inBuffer + conn->inStart,
374  conn->inEnd - conn->inStart);
375  conn->inEnd -= conn->inStart;
376  conn->inCursor -= conn->inStart;
377  conn->inStart = 0;
378  }
379  }
380  else
381  {
382  /* buffer is logically empty, reset it */
383  conn->inStart = conn->inCursor = conn->inEnd = 0;
384  }
385 
386  /* Recheck whether we have enough space */
387  if (bytes_needed <= (size_t) newsize)
388  return 0;
389 
390  /*
391  * If we need to enlarge the buffer, we first try to double it in size; if
392  * that doesn't work, enlarge in multiples of 8K. This avoids thrashing
393  * the malloc pool by repeated small enlargements.
394  *
395  * Note: tests for newsize > 0 are to catch integer overflow.
396  */
397  do
398  {
399  newsize *= 2;
400  } while (newsize > 0 && bytes_needed > (size_t) newsize);
401 
402  if (newsize > 0 && bytes_needed <= (size_t) newsize)
403  {
404  newbuf = realloc(conn->inBuffer, newsize);
405  if (newbuf)
406  {
407  /* realloc succeeded */
408  conn->inBuffer = newbuf;
409  conn->inBufSize = newsize;
410  return 0;
411  }
412  }
413 
414  newsize = conn->inBufSize;
415  do
416  {
417  newsize += 8192;
418  } while (newsize > 0 && bytes_needed > (size_t) newsize);
419 
420  if (newsize > 0 && bytes_needed <= (size_t) newsize)
421  {
422  newbuf = realloc(conn->inBuffer, newsize);
423  if (newbuf)
424  {
425  /* realloc succeeded */
426  conn->inBuffer = newbuf;
427  conn->inBufSize = newsize;
428  return 0;
429  }
430  }
431 
432  /* realloc failed. Probably out of memory */
434  "cannot allocate memory for input buffer\n");
435  return EOF;
436 }
437 
438 /*
439  * pqPutMsgStart: begin construction of a message to the server
440  *
441  * msg_type is the message type byte, or 0 for a message without type byte
442  * (only startup messages have no type byte)
443  *
444  * Returns 0 on success, EOF on error
445  *
446  * The idea here is that we construct the message in conn->outBuffer,
447  * beginning just past any data already in outBuffer (ie, at
448  * outBuffer+outCount). We enlarge the buffer as needed to hold the message.
449  * When the message is complete, we fill in the length word (if needed) and
450  * then advance outCount past the message, making it eligible to send.
451  *
452  * The state variable conn->outMsgStart points to the incomplete message's
453  * length word: it is either outCount or outCount+1 depending on whether
454  * there is a type byte. The state variable conn->outMsgEnd is the end of
455  * the data collected so far.
456  */
457 int
458 pqPutMsgStart(char msg_type, PGconn *conn)
459 {
460  int lenPos;
461  int endPos;
462 
463  /* allow room for message type byte */
464  if (msg_type)
465  endPos = conn->outCount + 1;
466  else
467  endPos = conn->outCount;
468 
469  /* do we want a length word? */
470  lenPos = endPos;
471  /* allow room for message length */
472  endPos += 4;
473 
474  /* make sure there is room for message header */
475  if (pqCheckOutBufferSpace(endPos, conn))
476  return EOF;
477  /* okay, save the message type byte if any */
478  if (msg_type)
479  conn->outBuffer[conn->outCount] = msg_type;
480  /* set up the message pointers */
481  conn->outMsgStart = lenPos;
482  conn->outMsgEnd = endPos;
483  /* length word, if needed, will be filled in by pqPutMsgEnd */
484 
485  return 0;
486 }
487 
488 /*
489  * pqPutMsgBytes: add bytes to a partially-constructed message
490  *
491  * Returns 0 on success, EOF on error
492  */
493 static int
494 pqPutMsgBytes(const void *buf, size_t len, PGconn *conn)
495 {
496  /* make sure there is room for it */
498  return EOF;
499  /* okay, save the data */
500  memcpy(conn->outBuffer + conn->outMsgEnd, buf, len);
501  conn->outMsgEnd += len;
502  /* no Pfdebug call here, caller should do it */
503  return 0;
504 }
505 
506 /*
507  * pqPutMsgEnd: finish constructing a message and possibly send it
508  *
509  * Returns 0 on success, EOF on error
510  *
511  * We don't actually send anything here unless we've accumulated at least
512  * 8K worth of data (the typical size of a pipe buffer on Unix systems).
513  * This avoids sending small partial packets. The caller must use pqFlush
514  * when it's important to flush all the data out to the server.
515  */
516 int
518 {
519  /* Fill in length word if needed */
520  if (conn->outMsgStart >= 0)
521  {
522  uint32 msgLen = conn->outMsgEnd - conn->outMsgStart;
523 
524  msgLen = pg_hton32(msgLen);
525  memcpy(conn->outBuffer + conn->outMsgStart, &msgLen, 4);
526  }
527 
528  /* trace client-to-server message */
529  if (conn->Pfdebug)
530  {
531  if (conn->outCount < conn->outMsgStart)
533  else
536  }
537 
538  /* Make message eligible to send */
540 
541  if (conn->outCount >= 8192)
542  {
543  int toSend = conn->outCount - (conn->outCount % 8192);
544 
545  if (pqSendSome(conn, toSend) < 0)
546  return EOF;
547  /* in nonblock mode, don't complain if unable to send it all */
548  }
549 
550  return 0;
551 }
552 
553 /* ----------
554  * pqReadData: read more data, if any is available
555  * Possible return values:
556  * 1: successfully loaded at least one more byte
557  * 0: no data is presently available, but no error detected
558  * -1: error detected (including EOF = connection closure);
559  * conn->errorMessage set
560  * NOTE: callers must not assume that pointers or indexes into conn->inBuffer
561  * remain valid across this call!
562  * ----------
563  */
564 int
566 {
567  int someread = 0;
568  int nread;
569 
570  if (conn->sock == PGINVALID_SOCKET)
571  {
572  libpq_append_conn_error(conn, "connection not open");
573  return -1;
574  }
575 
576  /* Left-justify any data in the buffer to make room */
577  if (conn->inStart < conn->inEnd)
578  {
579  if (conn->inStart > 0)
580  {
581  memmove(conn->inBuffer, conn->inBuffer + conn->inStart,
582  conn->inEnd - conn->inStart);
583  conn->inEnd -= conn->inStart;
584  conn->inCursor -= conn->inStart;
585  conn->inStart = 0;
586  }
587  }
588  else
589  {
590  /* buffer is logically empty, reset it */
591  conn->inStart = conn->inCursor = conn->inEnd = 0;
592  }
593 
594  /*
595  * If the buffer is fairly full, enlarge it. We need to be able to enlarge
596  * the buffer in case a single message exceeds the initial buffer size. We
597  * enlarge before filling the buffer entirely so as to avoid asking the
598  * kernel for a partial packet. The magic constant here should be large
599  * enough for a TCP packet or Unix pipe bufferload. 8K is the usual pipe
600  * buffer size, so...
601  */
602  if (conn->inBufSize - conn->inEnd < 8192)
603  {
604  if (pqCheckInBufferSpace(conn->inEnd + (size_t) 8192, conn))
605  {
606  /*
607  * We don't insist that the enlarge worked, but we need some room
608  */
609  if (conn->inBufSize - conn->inEnd < 100)
610  return -1; /* errorMessage already set */
611  }
612  }
613 
614  /* OK, try to read some data */
615 retry3:
616  nread = pqsecure_read(conn, conn->inBuffer + conn->inEnd,
617  conn->inBufSize - conn->inEnd);
618  if (nread < 0)
619  {
620  switch (SOCK_ERRNO)
621  {
622  case EINTR:
623  goto retry3;
624 
625  /* Some systems return EAGAIN/EWOULDBLOCK for no data */
626 #ifdef EAGAIN
627  case EAGAIN:
628  return someread;
629 #endif
630 #if defined(EWOULDBLOCK) && (!defined(EAGAIN) || (EWOULDBLOCK != EAGAIN))
631  case EWOULDBLOCK:
632  return someread;
633 #endif
634 
635  /* We might get ECONNRESET etc here if connection failed */
637  goto definitelyFailed;
638 
639  default:
640  /* pqsecure_read set the error message for us */
641  return -1;
642  }
643  }
644  if (nread > 0)
645  {
646  conn->inEnd += nread;
647 
648  /*
649  * Hack to deal with the fact that some kernels will only give us back
650  * 1 packet per recv() call, even if we asked for more and there is
651  * more available. If it looks like we are reading a long message,
652  * loop back to recv() again immediately, until we run out of data or
653  * buffer space. Without this, the block-and-restart behavior of
654  * libpq's higher levels leads to O(N^2) performance on long messages.
655  *
656  * Since we left-justified the data above, conn->inEnd gives the
657  * amount of data already read in the current message. We consider
658  * the message "long" once we have acquired 32k ...
659  */
660  if (conn->inEnd > 32768 &&
661  (conn->inBufSize - conn->inEnd) >= 8192)
662  {
663  someread = 1;
664  goto retry3;
665  }
666  return 1;
667  }
668 
669  if (someread)
670  return 1; /* got a zero read after successful tries */
671 
672  /*
673  * A return value of 0 could mean just that no data is now available, or
674  * it could mean EOF --- that is, the server has closed the connection.
675  * Since we have the socket in nonblock mode, the only way to tell the
676  * difference is to see if select() is saying that the file is ready.
677  * Grumble. Fortunately, we don't expect this path to be taken much,
678  * since in normal practice we should not be trying to read data unless
679  * the file selected for reading already.
680  *
681  * In SSL mode it's even worse: SSL_read() could say WANT_READ and then
682  * data could arrive before we make the pqReadReady() test, but the second
683  * SSL_read() could still say WANT_READ because the data received was not
684  * a complete SSL record. So we must play dumb and assume there is more
685  * data, relying on the SSL layer to detect true EOF.
686  */
687 
688 #ifdef USE_SSL
689  if (conn->ssl_in_use)
690  return 0;
691 #endif
692 
693  switch (pqReadReady(conn))
694  {
695  case 0:
696  /* definitely no data available */
697  return 0;
698  case 1:
699  /* ready for read */
700  break;
701  default:
702  /* we override pqReadReady's message with something more useful */
703  goto definitelyEOF;
704  }
705 
706  /*
707  * Still not sure that it's EOF, because some data could have just
708  * arrived.
709  */
710 retry4:
711  nread = pqsecure_read(conn, conn->inBuffer + conn->inEnd,
712  conn->inBufSize - conn->inEnd);
713  if (nread < 0)
714  {
715  switch (SOCK_ERRNO)
716  {
717  case EINTR:
718  goto retry4;
719 
720  /* Some systems return EAGAIN/EWOULDBLOCK for no data */
721 #ifdef EAGAIN
722  case EAGAIN:
723  return 0;
724 #endif
725 #if defined(EWOULDBLOCK) && (!defined(EAGAIN) || (EWOULDBLOCK != EAGAIN))
726  case EWOULDBLOCK:
727  return 0;
728 #endif
729 
730  /* We might get ECONNRESET etc here if connection failed */
732  goto definitelyFailed;
733 
734  default:
735  /* pqsecure_read set the error message for us */
736  return -1;
737  }
738  }
739  if (nread > 0)
740  {
741  conn->inEnd += nread;
742  return 1;
743  }
744 
745  /*
746  * OK, we are getting a zero read even though select() says ready. This
747  * means the connection has been closed. Cope.
748  */
749 definitelyEOF:
750  libpq_append_conn_error(conn, "server closed the connection unexpectedly\n"
751  "\tThis probably means the server terminated abnormally\n"
752  "\tbefore or while processing the request.");
753 
754  /* Come here if lower-level code already set a suitable errorMessage */
755 definitelyFailed:
756  /* Do *not* drop any already-read data; caller still wants it */
757  pqDropConnection(conn, false);
758  conn->status = CONNECTION_BAD; /* No more connection to backend */
759  return -1;
760 }
761 
762 /*
763  * pqSendSome: send data waiting in the output buffer.
764  *
765  * len is how much to try to send (typically equal to outCount, but may
766  * be less).
767  *
768  * Return 0 on success, -1 on failure and 1 when not all data could be sent
769  * because the socket would block and the connection is non-blocking.
770  *
771  * Note that this is also responsible for consuming data from the socket
772  * (putting it in conn->inBuffer) in any situation where we can't send
773  * all the specified data immediately.
774  *
775  * If a socket-level write failure occurs, conn->write_failed is set and the
776  * error message is saved in conn->write_err_msg, but we clear the output
777  * buffer and return zero anyway; this is because callers should soldier on
778  * until we have read what we can from the server and checked for an error
779  * message. write_err_msg should be reported only when we are unable to
780  * obtain a server error first. Much of that behavior is implemented at
781  * lower levels, but this function deals with some edge cases.
782  */
783 static int
785 {
786  char *ptr = conn->outBuffer;
787  int remaining = conn->outCount;
788  int result = 0;
789 
790  /*
791  * If we already had a write failure, we will never again try to send data
792  * on that connection. Even if the kernel would let us, we've probably
793  * lost message boundary sync with the server. conn->write_failed
794  * therefore persists until the connection is reset, and we just discard
795  * all data presented to be written. However, as long as we still have a
796  * valid socket, we should continue to absorb data from the backend, so
797  * that we can collect any final error messages.
798  */
799  if (conn->write_failed)
800  {
801  /* conn->write_err_msg should be set up already */
802  conn->outCount = 0;
803  /* Absorb input data if any, and detect socket closure */
804  if (conn->sock != PGINVALID_SOCKET)
805  {
806  if (pqReadData(conn) < 0)
807  return -1;
808  }
809  return 0;
810  }
811 
812  if (conn->sock == PGINVALID_SOCKET)
813  {
814  conn->write_failed = true;
815  /* Store error message in conn->write_err_msg, if possible */
816  /* (strdup failure is OK, we'll cope later) */
817  conn->write_err_msg = strdup(libpq_gettext("connection not open\n"));
818  /* Discard queued data; no chance it'll ever be sent */
819  conn->outCount = 0;
820  return 0;
821  }
822 
823  /* while there's still data to send */
824  while (len > 0)
825  {
826  int sent;
827 
828 #ifndef WIN32
829  sent = pqsecure_write(conn, ptr, len);
830 #else
831 
832  /*
833  * Windows can fail on large sends, per KB article Q201213. The
834  * failure-point appears to be different in different versions of
835  * Windows, but 64k should always be safe.
836  */
837  sent = pqsecure_write(conn, ptr, Min(len, 65536));
838 #endif
839 
840  if (sent < 0)
841  {
842  /* Anything except EAGAIN/EWOULDBLOCK/EINTR is trouble */
843  switch (SOCK_ERRNO)
844  {
845 #ifdef EAGAIN
846  case EAGAIN:
847  break;
848 #endif
849 #if defined(EWOULDBLOCK) && (!defined(EAGAIN) || (EWOULDBLOCK != EAGAIN))
850  case EWOULDBLOCK:
851  break;
852 #endif
853  case EINTR:
854  continue;
855 
856  default:
857  /* Discard queued data; no chance it'll ever be sent */
858  conn->outCount = 0;
859 
860  /* Absorb input data if any, and detect socket closure */
861  if (conn->sock != PGINVALID_SOCKET)
862  {
863  if (pqReadData(conn) < 0)
864  return -1;
865  }
866 
867  /*
868  * Lower-level code should already have filled
869  * conn->write_err_msg (and set conn->write_failed) or
870  * conn->errorMessage. In the former case, we pretend
871  * there's no problem; the write_failed condition will be
872  * dealt with later. Otherwise, report the error now.
873  */
874  if (conn->write_failed)
875  return 0;
876  else
877  return -1;
878  }
879  }
880  else
881  {
882  ptr += sent;
883  len -= sent;
884  remaining -= sent;
885  }
886 
887  if (len > 0)
888  {
889  /*
890  * We didn't send it all, wait till we can send more.
891  *
892  * There are scenarios in which we can't send data because the
893  * communications channel is full, but we cannot expect the server
894  * to clear the channel eventually because it's blocked trying to
895  * send data to us. (This can happen when we are sending a large
896  * amount of COPY data, and the server has generated lots of
897  * NOTICE responses.) To avoid a deadlock situation, we must be
898  * prepared to accept and buffer incoming data before we try
899  * again. Furthermore, it is possible that such incoming data
900  * might not arrive until after we've gone to sleep. Therefore,
901  * we wait for either read ready or write ready.
902  *
903  * In non-blocking mode, we don't wait here directly, but return 1
904  * to indicate that data is still pending. The caller should wait
905  * for both read and write ready conditions, and call
906  * PQconsumeInput() on read ready, but just in case it doesn't, we
907  * call pqReadData() ourselves before returning. That's not
908  * enough if the data has not arrived yet, but it's the best we
909  * can do, and works pretty well in practice. (The documentation
910  * used to say that you only need to wait for write-ready, so
911  * there are still plenty of applications like that out there.)
912  *
913  * Note that errors here don't result in write_failed becoming
914  * set.
915  */
916  if (pqReadData(conn) < 0)
917  {
918  result = -1; /* error message already set up */
919  break;
920  }
921 
922  if (pqIsnonblocking(conn))
923  {
924  result = 1;
925  break;
926  }
927 
928  if (pqWait(true, true, conn))
929  {
930  result = -1;
931  break;
932  }
933  }
934  }
935 
936  /* shift the remaining contents of the buffer */
937  if (remaining > 0)
938  memmove(conn->outBuffer, ptr, remaining);
940 
941  return result;
942 }
943 
944 
945 /*
946  * pqFlush: send any data waiting in the output buffer
947  *
948  * Return 0 on success, -1 on failure and 1 when not all data could be sent
949  * because the socket would block and the connection is non-blocking.
950  * (See pqSendSome comments about how failure should be handled.)
951  */
952 int
954 {
955  if (conn->outCount > 0)
956  {
957  if (conn->Pfdebug)
958  fflush(conn->Pfdebug);
959 
960  return pqSendSome(conn, conn->outCount);
961  }
962 
963  return 0;
964 }
965 
966 
967 /*
968  * pqWait: wait until we can read or write the connection socket
969  *
970  * JAB: If SSL enabled and used and forRead, buffered bytes short-circuit the
971  * call to select().
972  *
973  * We also stop waiting and return if the kernel flags an exception condition
974  * on the socket. The actual error condition will be detected and reported
975  * when the caller tries to read or write the socket.
976  */
977 int
978 pqWait(int forRead, int forWrite, PGconn *conn)
979 {
980  return pqWaitTimed(forRead, forWrite, conn, -1);
981 }
982 
983 /*
984  * pqWaitTimed: wait, but not past end_time.
985  *
986  * Returns -1 on failure, 0 if the socket is readable/writable, 1 if it timed out.
987  *
988  * The timeout is specified by end_time, which is the int64 number of
989  * microseconds since the Unix epoch (that is, time_t times 1 million).
990  * Timeout is infinite if end_time is -1. Timeout is immediate (no blocking)
991  * if end_time is 0 (or indeed, any time before now).
992  */
993 int
994 pqWaitTimed(int forRead, int forWrite, PGconn *conn, pg_usec_time_t end_time)
995 {
996  int result;
997 
998  result = pqSocketCheck(conn, forRead, forWrite, end_time);
999 
1000  if (result < 0)
1001  return -1; /* errorMessage is already set */
1002 
1003  if (result == 0)
1004  {
1005  libpq_append_conn_error(conn, "timeout expired");
1006  return 1;
1007  }
1008 
1009  return 0;
1010 }
1011 
1012 /*
1013  * pqReadReady: is select() saying the file is ready to read?
1014  * Returns -1 on failure, 0 if not ready, 1 if ready.
1015  */
1016 int
1018 {
1019  return pqSocketCheck(conn, 1, 0, 0);
1020 }
1021 
1022 /*
1023  * pqWriteReady: is select() saying the file is ready to write?
1024  * Returns -1 on failure, 0 if not ready, 1 if ready.
1025  */
1026 int
1028 {
1029  return pqSocketCheck(conn, 0, 1, 0);
1030 }
1031 
1032 /*
1033  * Checks a socket, using poll or select, for data to be read, written,
1034  * or both. Returns >0 if one or more conditions are met, 0 if it timed
1035  * out, -1 if an error occurred.
1036  *
1037  * If SSL is in use, the SSL buffer is checked prior to checking the socket
1038  * for read data directly.
1039  */
1040 static int
1041 pqSocketCheck(PGconn *conn, int forRead, int forWrite, pg_usec_time_t end_time)
1042 {
1043  int result;
1044 
1045  if (!conn)
1046  return -1;
1047  if (conn->sock == PGINVALID_SOCKET)
1048  {
1049  libpq_append_conn_error(conn, "invalid socket");
1050  return -1;
1051  }
1052 
1053 #ifdef USE_SSL
1054  /* Check for SSL library buffering read bytes */
1055  if (forRead && conn->ssl_in_use && pgtls_read_pending(conn))
1056  {
1057  /* short-circuit the select */
1058  return 1;
1059  }
1060 #endif
1061 
1062  /* We will retry as long as we get EINTR */
1063  do
1064  result = PQsocketPoll(conn->sock, forRead, forWrite, end_time);
1065  while (result < 0 && SOCK_ERRNO == EINTR);
1066 
1067  if (result < 0)
1068  {
1069  char sebuf[PG_STRERROR_R_BUFLEN];
1070 
1071  libpq_append_conn_error(conn, "%s() failed: %s", "select",
1072  SOCK_STRERROR(SOCK_ERRNO, sebuf, sizeof(sebuf)));
1073  }
1074 
1075  return result;
1076 }
1077 
1078 
1079 /*
1080  * Check a file descriptor for read and/or write data, possibly waiting.
1081  * If neither forRead nor forWrite are set, immediately return a timeout
1082  * condition (without waiting). Return >0 if condition is met, 0
1083  * if a timeout occurred, -1 if an error or interrupt occurred.
1084  *
1085  * The timeout is specified by end_time, which is the int64 number of
1086  * microseconds since the Unix epoch (that is, time_t times 1 million).
1087  * Timeout is infinite if end_time is -1. Timeout is immediate (no blocking)
1088  * if end_time is 0 (or indeed, any time before now).
1089  */
1090 int
1091 PQsocketPoll(int sock, int forRead, int forWrite, pg_usec_time_t end_time)
1092 {
1093  /* We use poll(2) if available, otherwise select(2) */
1094 #ifdef HAVE_POLL
1095  struct pollfd input_fd;
1096  int timeout_ms;
1097 
1098  if (!forRead && !forWrite)
1099  return 0;
1100 
1101  input_fd.fd = sock;
1102  input_fd.events = POLLERR;
1103  input_fd.revents = 0;
1104 
1105  if (forRead)
1106  input_fd.events |= POLLIN;
1107  if (forWrite)
1108  input_fd.events |= POLLOUT;
1109 
1110  /* Compute appropriate timeout interval */
1111  if (end_time == -1)
1112  timeout_ms = -1;
1113  else if (end_time == 0)
1114  timeout_ms = 0;
1115  else
1116  {
1118 
1119  if (end_time > now)
1120  timeout_ms = (end_time - now) / 1000;
1121  else
1122  timeout_ms = 0;
1123  }
1124 
1125  return poll(&input_fd, 1, timeout_ms);
1126 #else /* !HAVE_POLL */
1127 
1128  fd_set input_mask;
1129  fd_set output_mask;
1130  fd_set except_mask;
1131  struct timeval timeout;
1132  struct timeval *ptr_timeout;
1133 
1134  if (!forRead && !forWrite)
1135  return 0;
1136 
1137  FD_ZERO(&input_mask);
1138  FD_ZERO(&output_mask);
1139  FD_ZERO(&except_mask);
1140  if (forRead)
1141  FD_SET(sock, &input_mask);
1142 
1143  if (forWrite)
1144  FD_SET(sock, &output_mask);
1145  FD_SET(sock, &except_mask);
1146 
1147  /* Compute appropriate timeout interval */
1148  if (end_time == -1)
1149  ptr_timeout = NULL;
1150  else if (end_time == 0)
1151  {
1152  timeout.tv_sec = 0;
1153  timeout.tv_usec = 0;
1154  ptr_timeout = &timeout;
1155  }
1156  else
1157  {
1159 
1160  if (end_time > now)
1161  {
1162  timeout.tv_sec = (end_time - now) / 1000000;
1163  timeout.tv_usec = (end_time - now) % 1000000;
1164  }
1165  else
1166  {
1167  timeout.tv_sec = 0;
1168  timeout.tv_usec = 0;
1169  }
1170  ptr_timeout = &timeout;
1171  }
1172 
1173  return select(sock + 1, &input_mask, &output_mask,
1174  &except_mask, ptr_timeout);
1175 #endif /* HAVE_POLL */
1176 }
1177 
1178 /*
1179  * PQgetCurrentTimeUSec: get current time with microsecond precision
1180  *
1181  * This provides a platform-independent way of producing a reference
1182  * value for PQsocketPoll's timeout parameter.
1183  */
1186 {
1187  struct timeval tval;
1188 
1189  gettimeofday(&tval, NULL);
1190  return (pg_usec_time_t) tval.tv_sec * 1000000 + tval.tv_usec;
1191 }
1192 
1193 
1194 /*
1195  * A couple of "miscellaneous" multibyte related functions. They used
1196  * to be in fe-print.c but that file is doomed.
1197  */
1198 
1199 /*
1200  * Returns the byte length of the character beginning at s, using the
1201  * specified encoding.
1202  *
1203  * Caution: when dealing with text that is not certainly valid in the
1204  * specified encoding, the result may exceed the actual remaining
1205  * string length. Callers that are not prepared to deal with that
1206  * should use PQmblenBounded() instead.
1207  */
1208 int
1209 PQmblen(const char *s, int encoding)
1210 {
1211  return pg_encoding_mblen(encoding, s);
1212 }
1213 
1214 /*
1215  * Returns the byte length of the character beginning at s, using the
1216  * specified encoding; but not more than the distance to end of string.
1217  */
1218 int
1219 PQmblenBounded(const char *s, int encoding)
1220 {
1221  return strnlen(s, pg_encoding_mblen(encoding, s));
1222 }
1223 
1224 /*
1225  * Returns the display length of the character beginning at s, using the
1226  * specified encoding.
1227  */
1228 int
1229 PQdsplen(const char *s, int encoding)
1230 {
1231  return pg_encoding_dsplen(encoding, s);
1232 }
1233 
1234 /*
1235  * Get encoding id from environment variable PGCLIENTENCODING.
1236  */
1237 int
1239 {
1240  char *str;
1241  int encoding = PG_SQL_ASCII;
1242 
1243  str = getenv("PGCLIENTENCODING");
1244  if (str && *str != '\0')
1245  {
1247  if (encoding < 0)
1249  }
1250  return encoding;
1251 }
1252 
1253 
1254 #ifdef ENABLE_NLS
1255 
1256 static void
1257 libpq_binddomain(void)
1258 {
1259  /*
1260  * At least on Windows, there are gettext implementations that fail if
1261  * multiple threads call bindtextdomain() concurrently. Use a mutex and
1262  * flag variable to ensure that we call it just once per process. It is
1263  * not known that similar bugs exist on non-Windows platforms, but we
1264  * might as well do it the same way everywhere.
1265  */
1266  static volatile bool already_bound = false;
1267  static pthread_mutex_t binddomain_mutex = PTHREAD_MUTEX_INITIALIZER;
1268 
1269  if (!already_bound)
1270  {
1271  /* bindtextdomain() does not preserve errno */
1272 #ifdef WIN32
1273  int save_errno = GetLastError();
1274 #else
1275  int save_errno = errno;
1276 #endif
1277 
1278  (void) pthread_mutex_lock(&binddomain_mutex);
1279 
1280  if (!already_bound)
1281  {
1282  const char *ldir;
1283 
1284  /*
1285  * No relocatable lookup here because the calling executable could
1286  * be anywhere
1287  */
1288  ldir = getenv("PGLOCALEDIR");
1289  if (!ldir)
1290  ldir = LOCALEDIR;
1291  bindtextdomain(PG_TEXTDOMAIN("libpq"), ldir);
1292  already_bound = true;
1293  }
1294 
1295  (void) pthread_mutex_unlock(&binddomain_mutex);
1296 
1297 #ifdef WIN32
1298  SetLastError(save_errno);
1299 #else
1300  errno = save_errno;
1301 #endif
1302  }
1303 }
1304 
1305 char *
1306 libpq_gettext(const char *msgid)
1307 {
1308  libpq_binddomain();
1309  return dgettext(PG_TEXTDOMAIN("libpq"), msgid);
1310 }
1311 
1312 char *
1313 libpq_ngettext(const char *msgid, const char *msgid_plural, unsigned long n)
1314 {
1315  libpq_binddomain();
1316  return dngettext(PG_TEXTDOMAIN("libpq"), msgid, msgid_plural, n);
1317 }
1318 
1319 #endif /* ENABLE_NLS */
1320 
1321 
1322 /*
1323  * Append a formatted string to the given buffer, after translating it. A
1324  * newline is automatically appended; the format should not end with a
1325  * newline.
1326  */
1327 void
1328 libpq_append_error(PQExpBuffer errorMessage, const char *fmt,...)
1329 {
1330  int save_errno = errno;
1331  bool done;
1332  va_list args;
1333 
1334  Assert(fmt[strlen(fmt) - 1] != '\n');
1335 
1336  if (PQExpBufferBroken(errorMessage))
1337  return; /* already failed */
1338 
1339  /* Loop in case we have to retry after enlarging the buffer. */
1340  do
1341  {
1342  errno = save_errno;
1343  va_start(args, fmt);
1344  done = appendPQExpBufferVA(errorMessage, libpq_gettext(fmt), args);
1345  va_end(args);
1346  } while (!done);
1347 
1348  appendPQExpBufferChar(errorMessage, '\n');
1349 }
1350 
1351 /*
1352  * Append a formatted string to the error message buffer of the given
1353  * connection, after translating it. A newline is automatically appended; the
1354  * format should not end with a newline.
1355  */
1356 void
1358 {
1359  int save_errno = errno;
1360  bool done;
1361  va_list args;
1362 
1363  Assert(fmt[strlen(fmt) - 1] != '\n');
1364 
1366  return; /* already failed */
1367 
1368  /* Loop in case we have to retry after enlarging the buffer. */
1369  do
1370  {
1371  errno = save_errno;
1372  va_start(args, fmt);
1374  va_end(args);
1375  } while (!done);
1376 
1378 }
Datum now(PG_FUNCTION_ARGS)
Definition: timestamp.c:1618
unsigned short uint16
Definition: c.h:505
unsigned int uint32
Definition: c.h:506
#define Min(x, y)
Definition: c.h:1004
#define Assert(condition)
Definition: c.h:858
#define PG_TEXTDOMAIN(domain)
Definition: c.h:1214
#define dngettext(d, s, p, n)
Definition: c.h:1182
#define dgettext(d, x)
Definition: c.h:1180
void pqDropConnection(PGconn *conn, bool flushInput)
Definition: fe-connect.c:471
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Definition: fe-misc.c:92
int pqReadData(PGconn *conn)
Definition: fe-misc.c:565
int pqPutInt(int value, size_t bytes, PGconn *conn)
Definition: fe-misc.c:253
int pqCheckOutBufferSpace(size_t bytes_needed, PGconn *conn)
Definition: fe-misc.c:287
int pqFlush(PGconn *conn)
Definition: fe-misc.c:953
int pqReadReady(PGconn *conn)
Definition: fe-misc.c:1017
static int pqSocketCheck(PGconn *conn, int forRead, int forWrite, pg_usec_time_t end_time)
Definition: fe-misc.c:1041
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Definition: fe-misc.c:1238
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Definition: fe-misc.c:458
int pqSkipnchar(size_t len, PGconn *conn)
Definition: fe-misc.c:187
int PQsocketPoll(int sock, int forRead, int forWrite, pg_usec_time_t end_time)
Definition: fe-misc.c:1091
int pqGetc(char *result, PGconn *conn)
Definition: fe-misc.c:77
int PQlibVersion(void)
Definition: fe-misc.c:63
int pqGetInt(int *result, size_t bytes, PGconn *conn)
Definition: fe-misc.c:216
int pqGetnchar(char *s, size_t len, PGconn *conn)
Definition: fe-misc.c:165
int PQmblen(const char *s, int encoding)
Definition: fe-misc.c:1209
int pqWait(int forRead, int forWrite, PGconn *conn)
Definition: fe-misc.c:978
int pqGets(PQExpBuffer buf, PGconn *conn)
Definition: fe-misc.c:136
int PQdsplen(const char *s, int encoding)
Definition: fe-misc.c:1229
int pqCheckInBufferSpace(size_t bytes_needed, PGconn *conn)
Definition: fe-misc.c:351
static int pqPutMsgBytes(const void *buf, size_t len, PGconn *conn)
Definition: fe-misc.c:494
int pqPutnchar(const char *s, size_t len, PGconn *conn)
Definition: fe-misc.c:202
static int pqSendSome(PGconn *conn, int len)
Definition: fe-misc.c:784
pg_usec_time_t PQgetCurrentTimeUSec(void)
Definition: fe-misc.c:1185
static int pqGets_internal(PQExpBuffer buf, PGconn *conn, bool resetbuffer)
Definition: fe-misc.c:109
int pqPuts(const char *s, PGconn *conn)
Definition: fe-misc.c:152
void libpq_append_error(PQExpBuffer errorMessage, const char *fmt,...)
Definition: fe-misc.c:1328
int PQmblenBounded(const char *s, int encoding)
Definition: fe-misc.c:1219
void libpq_append_conn_error(PGconn *conn, const char *fmt,...)
Definition: fe-misc.c:1357
int pqWaitTimed(int forRead, int forWrite, PGconn *conn, pg_usec_time_t end_time)
Definition: fe-misc.c:994
int pqGets_append(PQExpBuffer buf, PGconn *conn)
Definition: fe-misc.c:142
int pqWriteReady(PGconn *conn)
Definition: fe-misc.c:1027
int pqPutMsgEnd(PGconn *conn)
Definition: fe-misc.c:517
bool pgtls_read_pending(PGconn *conn)
ssize_t pqsecure_write(PGconn *conn, const void *ptr, size_t len)
Definition: fe-secure.c:282
ssize_t pqsecure_read(PGconn *conn, void *ptr, size_t len)
Definition: fe-secure.c:182
void pqTraceOutputMessage(PGconn *conn, const char *message, bool toServer)
Definition: fe-trace.c:514
void pqTraceOutputNoTypeByteMessage(PGconn *conn, const char *message)
Definition: fe-trace.c:696
const char * str
#define realloc(a, b)
Definition: header.h:60
static struct @155 value
int remaining
Definition: informix.c:673
@ CONNECTION_BAD
Definition: libpq-fe.h:61
pg_int64 pg_usec_time_t
Definition: libpq-fe.h:205
#define libpq_gettext(x)
Definition: libpq-int.h:911
#define SOCK_STRERROR
Definition: libpq-int.h:933
#define SOCK_ERRNO
Definition: libpq-int.h:932
#define libpq_ngettext(s, p, n)
Definition: libpq-int.h:912
#define pqIsnonblocking(conn)
Definition: libpq-int.h:900
static void const char * fmt
static void const char fflush(stdout)
va_end(args)
va_start(args, fmt)
#define pg_ntoh32(x)
Definition: pg_bswap.h:125
#define pg_hton32(x)
Definition: pg_bswap.h:121
#define pg_hton16(x)
Definition: pg_bswap.h:120
#define pg_ntoh16(x)
Definition: pg_bswap.h:124
const void size_t len
int32 encoding
Definition: pg_database.h:41
static char * buf
Definition: pg_test_fsync.c:73
@ PG_SQL_ASCII
Definition: pg_wchar.h:226
#define pg_char_to_encoding
Definition: pg_wchar.h:629
int64 end_time
Definition: pgbench.c:175
#define PG_STRERROR_R_BUFLEN
Definition: port.h:256
#define ALL_CONNECTION_FAILURE_ERRNOS
Definition: port.h:121
#define PGINVALID_SOCKET
Definition: port.h:31
size_t strnlen(const char *str, size_t maxlen)
Definition: strnlen.c:26
void resetPQExpBuffer(PQExpBuffer str)
Definition: pqexpbuffer.c:146
void appendBinaryPQExpBuffer(PQExpBuffer str, const char *data, size_t datalen)
Definition: pqexpbuffer.c:397
bool appendPQExpBufferVA(PQExpBuffer str, const char *fmt, va_list args)
Definition: pqexpbuffer.c:294
void appendPQExpBufferChar(PQExpBuffer str, char ch)
Definition: pqexpbuffer.c:378
void appendPQExpBufferStr(PQExpBuffer str, const char *data)
Definition: pqexpbuffer.c:367
#define PQExpBufferBroken(str)
Definition: pqexpbuffer.h:59
char * c
int pthread_mutex_unlock(pthread_mutex_t *mp)
Definition: pthread-win32.c:60
int pthread_mutex_lock(pthread_mutex_t *mp)
Definition: pthread-win32.c:42
#define PTHREAD_MUTEX_INITIALIZER
Definition: pthread-win32.h:16
PGconn * conn
Definition: streamutil.c:55
char * write_err_msg
Definition: libpq-int.h:485
pgsocket sock
Definition: libpq-int.h:473
char * inBuffer
Definition: libpq-int.h:522
bool write_failed
Definition: libpq-int.h:484
int inCursor
Definition: libpq-int.h:525
int inEnd
Definition: libpq-int.h:526
int inBufSize
Definition: libpq-int.h:523
int inStart
Definition: libpq-int.h:524
PQExpBufferData errorMessage
Definition: libpq-int.h:633
int outBufSize
Definition: libpq-int.h:530
PGNoticeHooks noticeHooks
Definition: libpq-int.h:428
FILE * Pfdebug
Definition: libpq-int.h:424
int outMsgStart
Definition: libpq-int.h:534
int outCount
Definition: libpq-int.h:531
int outMsgEnd
Definition: libpq-int.h:536
bool ssl_in_use
Definition: libpq-int.h:566
char * outBuffer
Definition: libpq-int.h:529
ConnStatusType status
Definition: libpq-int.h:436
int pg_encoding_dsplen(int encoding, const char *mbstr)
Definition: wchar.c:2090
int pg_encoding_mblen(int encoding, const char *mbstr)
Definition: wchar.c:2069
#define EINTR
Definition: win32_port.h:374
#define EWOULDBLOCK
Definition: win32_port.h:380
#define EAGAIN
Definition: win32_port.h:372
#define select(n, r, w, e, timeout)
Definition: win32_port.h:495
int gettimeofday(struct timeval *tp, void *tzp)