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Diffstat (limited to 'libpq/fe-misc.c')
| -rw-r--r-- | libpq/fe-misc.c | 1267 |
1 files changed, 1267 insertions, 0 deletions
diff --git a/libpq/fe-misc.c b/libpq/fe-misc.c new file mode 100644 index 0000000..32da8ca --- /dev/null +++ b/libpq/fe-misc.c @@ -0,0 +1,1267 @@ +/*------------------------------------------------------------------------- + * + * FILE + * fe-misc.c + * + * DESCRIPTION + * miscellaneous useful functions + * + * The communication routines here are analogous to the ones in + * backend/libpq/pqcomm.c and backend/libpq/pqcomprim.c, but operate + * in the considerably different environment of the frontend libpq. + * In particular, we work with a bare nonblock-mode socket, rather than + * a stdio stream, so that we can avoid unwanted blocking of the application. + * + * XXX: MOVE DEBUG PRINTOUT TO HIGHER LEVEL. As is, block and restart + * will cause repeat printouts. + * + * We must speak the same transmitted data representations as the backend + * routines. + * + * + * Portions Copyright (c) 1996-2016, PostgreSQL Global Development Group + * Portions Copyright (c) 1994, Regents of the University of California + * + * IDENTIFICATION + * src/interfaces/libpq/fe-misc.c + * + *------------------------------------------------------------------------- + */ + +#include "postgres_fe.h" + +#include <signal.h> +#include <time.h> + +#include <netinet/in.h> +#include <arpa/inet.h> + +#ifdef WIN32 +#include "win32.h" +#else +#include <unistd.h> +#include <sys/time.h> +#endif + +#ifdef HAVE_POLL_H +#include <poll.h> +#endif +#ifdef HAVE_SYS_POLL_H +#include <sys/poll.h> +#endif +#ifdef HAVE_SYS_SELECT_H +#include <sys/select.h> +#endif + +#include "libpq-fe.h" +#include "libpq-int.h" +#include "mb/pg_wchar.h" +#include "pg_config_paths.h" + + +static int pqPutMsgBytes(const void *buf, size_t len, PGconn *conn); +static int pqSendSome(PGconn *conn, int len); +static int pqSocketCheck(PGconn *conn, int forRead, int forWrite, + time_t end_time); +static int pqSocketPoll(int sock, int forRead, int forWrite, time_t end_time); + +/* + * PQlibVersion: return the libpq version number + */ +int +PQlibVersion(void) +{ + return PG_VERSION_NUM; +} + +/* + * fputnbytes: print exactly N bytes to a file + * + * We avoid using %.*s here because it can misbehave if the data + * is not valid in what libc thinks is the prevailing encoding. + */ +static void +fputnbytes(FILE *f, const char *str, size_t n) +{ + while (n-- > 0) + fputc(*str++, f); +} + + +/* + * pqGetc: get 1 character from the connection + * + * All these routines return 0 on success, EOF on error. + * Note that for the Get routines, EOF only means there is not enough + * data in the buffer, not that there is necessarily a hard error. + */ +int +pqGetc(char *result, PGconn *conn) +{ + if (conn->inCursor >= conn->inEnd) + return EOF; + + *result = conn->inBuffer[conn->inCursor++]; + + if (conn->Pfdebug) + fprintf(conn->Pfdebug, "From backend> %c\n", *result); + + return 0; +} + + +/* + * pqPutc: write 1 char to the current message + */ +int +pqPutc(char c, PGconn *conn) +{ + if (pqPutMsgBytes(&c, 1, conn)) + return EOF; + + if (conn->Pfdebug) + fprintf(conn->Pfdebug, "To backend> %c\n", c); + + return 0; +} + + +/* + * pqGets[_append]: + * get a null-terminated string from the connection, + * and store it in an expansible PQExpBuffer. + * If we run out of memory, all of the string is still read, + * but the excess characters are silently discarded. + */ +static int +pqGets_internal(PQExpBuffer buf, PGconn *conn, bool resetbuffer) +{ + /* Copy conn data to locals for faster search loop */ + char *inBuffer = conn->inBuffer; + int inCursor = conn->inCursor; + int inEnd = conn->inEnd; + int slen; + + while (inCursor < inEnd && inBuffer[inCursor]) + inCursor++; + + if (inCursor >= inEnd) + return EOF; + + slen = inCursor - conn->inCursor; + + if (resetbuffer) + resetPQExpBuffer(buf); + + appendBinaryPQExpBuffer(buf, inBuffer + conn->inCursor, slen); + + conn->inCursor = ++inCursor; + + if (conn->Pfdebug) + fprintf(conn->Pfdebug, "From backend> \"%s\"\n", + buf->data); + + return 0; +} + +int +pqGets(PQExpBuffer buf, PGconn *conn) +{ + return pqGets_internal(buf, conn, true); +} + +int +pqGets_append(PQExpBuffer buf, PGconn *conn) +{ + return pqGets_internal(buf, conn, false); +} + + +/* + * pqPuts: write a null-terminated string to the current message + */ +int +pqPuts(const char *s, PGconn *conn) +{ + if (pqPutMsgBytes(s, strlen(s) + 1, conn)) + return EOF; + + if (conn->Pfdebug) + fprintf(conn->Pfdebug, "To backend> \"%s\"\n", s); + + return 0; +} + +/* + * pqGetnchar: + * get a string of exactly len bytes in buffer s, no null termination + */ +int +pqGetnchar(char *s, size_t len, PGconn *conn) +{ + if (len > (size_t) (conn->inEnd - conn->inCursor)) + return EOF; + + memcpy(s, conn->inBuffer + conn->inCursor, len); + /* no terminating null */ + + conn->inCursor += len; + + if (conn->Pfdebug) + { + fprintf(conn->Pfdebug, "From backend (%lu)> ", (unsigned long) len); + fputnbytes(conn->Pfdebug, s, len); + fprintf(conn->Pfdebug, "\n"); + } + + return 0; +} + +/* + * pqSkipnchar: + * skip over len bytes in input buffer. + * + * Note: this is primarily useful for its debug output, which should + * be exactly the same as for pqGetnchar. We assume the data in question + * will actually be used, but just isn't getting copied anywhere as yet. + */ +int +pqSkipnchar(size_t len, PGconn *conn) +{ + if (len > (size_t) (conn->inEnd - conn->inCursor)) + return EOF; + + if (conn->Pfdebug) + { + fprintf(conn->Pfdebug, "From backend (%lu)> ", (unsigned long) len); + fputnbytes(conn->Pfdebug, conn->inBuffer + conn->inCursor, len); + fprintf(conn->Pfdebug, "\n"); + } + + conn->inCursor += len; + + return 0; +} + +/* + * pqPutnchar: + * write exactly len bytes to the current message + */ +int +pqPutnchar(const char *s, size_t len, PGconn *conn) +{ + if (pqPutMsgBytes(s, len, conn)) + return EOF; + + if (conn->Pfdebug) + { + fprintf(conn->Pfdebug, "To backend> "); + fputnbytes(conn->Pfdebug, s, len); + fprintf(conn->Pfdebug, "\n"); + } + + return 0; +} + +/* + * pqGetInt + * read a 2 or 4 byte integer and convert from network byte order + * to local byte order + */ +int +pqGetInt(int *result, size_t bytes, PGconn *conn) +{ + uint16 tmp2; + uint32 tmp4; + + switch (bytes) + { + case 2: + if (conn->inCursor + 2 > conn->inEnd) + return EOF; + memcpy(&tmp2, conn->inBuffer + conn->inCursor, 2); + conn->inCursor += 2; + *result = (int) ntohs(tmp2); + break; + case 4: + if (conn->inCursor + 4 > conn->inEnd) + return EOF; + memcpy(&tmp4, conn->inBuffer + conn->inCursor, 4); + conn->inCursor += 4; + *result = (int) ntohl(tmp4); + break; + default: + pqInternalNotice(&conn->noticeHooks, + "integer of size %lu not supported by pqGetInt", + (unsigned long) bytes); + return EOF; + } + + if (conn->Pfdebug) + fprintf(conn->Pfdebug, "From backend (#%lu)> %d\n", (unsigned long) bytes, *result); + + return 0; +} + +/* + * pqPutInt + * write an integer of 2 or 4 bytes, converting from host byte order + * to network byte order. + */ +int +pqPutInt(int value, size_t bytes, PGconn *conn) +{ + uint16 tmp2; + uint32 tmp4; + + switch (bytes) + { + case 2: + tmp2 = htons((uint16) value); + if (pqPutMsgBytes((const char *) &tmp2, 2, conn)) + return EOF; + break; + case 4: + tmp4 = htonl((uint32) value); + if (pqPutMsgBytes((const char *) &tmp4, 4, conn)) + return EOF; + break; + default: + pqInternalNotice(&conn->noticeHooks, + "integer of size %lu not supported by pqPutInt", + (unsigned long) bytes); + return EOF; + } + + if (conn->Pfdebug) + fprintf(conn->Pfdebug, "To backend (%lu#)> %d\n", (unsigned long) bytes, value); + + return 0; +} + +/* + * Make sure conn's output buffer can hold bytes_needed bytes (caller must + * include already-stored data into the value!) + * + * Returns 0 on success, EOF if failed to enlarge buffer + */ +int +pqCheckOutBufferSpace(size_t bytes_needed, PGconn *conn) +{ + int newsize = conn->outBufSize; + char *newbuf; + + /* Quick exit if we have enough space */ + if (bytes_needed <= (size_t) newsize) + return 0; + + /* + * If we need to enlarge the buffer, we first try to double it in size; if + * that doesn't work, enlarge in multiples of 8K. This avoids thrashing + * the malloc pool by repeated small enlargements. + * + * Note: tests for newsize > 0 are to catch integer overflow. + */ + do + { + newsize *= 2; + } while (newsize > 0 && bytes_needed > (size_t) newsize); + + if (newsize > 0 && bytes_needed <= (size_t) newsize) + { + newbuf = realloc(conn->outBuffer, newsize); + if (newbuf) + { + /* realloc succeeded */ + conn->outBuffer = newbuf; + conn->outBufSize = newsize; + return 0; + } + } + + newsize = conn->outBufSize; + do + { + newsize += 8192; + } while (newsize > 0 && bytes_needed > (size_t) newsize); + + if (newsize > 0 && bytes_needed <= (size_t) newsize) + { + newbuf = realloc(conn->outBuffer, newsize); + if (newbuf) + { + /* realloc succeeded */ + conn->outBuffer = newbuf; + conn->outBufSize = newsize; + return 0; + } + } + + /* realloc failed. Probably out of memory */ + printfPQExpBuffer(&conn->errorMessage, + "cannot allocate memory for output buffer\n"); + return EOF; +} + +/* + * Make sure conn's input buffer can hold bytes_needed bytes (caller must + * include already-stored data into the value!) + * + * Returns 0 on success, EOF if failed to enlarge buffer + */ +int +pqCheckInBufferSpace(size_t bytes_needed, PGconn *conn) +{ + int newsize = conn->inBufSize; + char *newbuf; + + /* Quick exit if we have enough space */ + if (bytes_needed <= (size_t) newsize) + return 0; + + /* + * Before concluding that we need to enlarge the buffer, left-justify + * whatever is in it and recheck. The caller's value of bytes_needed + * includes any data to the left of inStart, but we can delete that in + * preference to enlarging the buffer. It's slightly ugly to have this + * function do this, but it's better than making callers worry about it. + */ + bytes_needed -= conn->inStart; + + if (conn->inStart < conn->inEnd) + { + if (conn->inStart > 0) + { + memmove(conn->inBuffer, conn->inBuffer + conn->inStart, + conn->inEnd - conn->inStart); + conn->inEnd -= conn->inStart; + conn->inCursor -= conn->inStart; + conn->inStart = 0; + } + } + else + { + /* buffer is logically empty, reset it */ + conn->inStart = conn->inCursor = conn->inEnd = 0; + } + + /* Recheck whether we have enough space */ + if (bytes_needed <= (size_t) newsize) + return 0; + + /* + * If we need to enlarge the buffer, we first try to double it in size; if + * that doesn't work, enlarge in multiples of 8K. This avoids thrashing + * the malloc pool by repeated small enlargements. + * + * Note: tests for newsize > 0 are to catch integer overflow. + */ + do + { + newsize *= 2; + } while (newsize > 0 && bytes_needed > (size_t) newsize); + + if (newsize > 0 && bytes_needed <= (size_t) newsize) + { + newbuf = realloc(conn->inBuffer, newsize); + if (newbuf) + { + /* realloc succeeded */ + conn->inBuffer = newbuf; + conn->inBufSize = newsize; + return 0; + } + } + + newsize = conn->inBufSize; + do + { + newsize += 8192; + } while (newsize > 0 && bytes_needed > (size_t) newsize); + + if (newsize > 0 && bytes_needed <= (size_t) newsize) + { + newbuf = realloc(conn->inBuffer, newsize); + if (newbuf) + { + /* realloc succeeded */ + conn->inBuffer = newbuf; + conn->inBufSize = newsize; + return 0; + } + } + + /* realloc failed. Probably out of memory */ + printfPQExpBuffer(&conn->errorMessage, + "cannot allocate memory for input buffer\n"); + return EOF; +} + +/* + * pqPutMsgStart: begin construction of a message to the server + * + * msg_type is the message type byte, or 0 for a message without type byte + * (only startup messages have no type byte) + * + * force_len forces the message to have a length word; otherwise, we add + * a length word if protocol 3. + * + * Returns 0 on success, EOF on error + * + * The idea here is that we construct the message in conn->outBuffer, + * beginning just past any data already in outBuffer (ie, at + * outBuffer+outCount). We enlarge the buffer as needed to hold the message. + * When the message is complete, we fill in the length word (if needed) and + * then advance outCount past the message, making it eligible to send. + * + * The state variable conn->outMsgStart points to the incomplete message's + * length word: it is either outCount or outCount+1 depending on whether + * there is a type byte. If we are sending a message without length word + * (pre protocol 3.0 only), then outMsgStart is -1. The state variable + * conn->outMsgEnd is the end of the data collected so far. + */ +int +pqPutMsgStart(char msg_type, bool force_len, PGconn *conn) +{ + int lenPos; + int endPos; + + /* allow room for message type byte */ + if (msg_type) + endPos = conn->outCount + 1; + else + endPos = conn->outCount; + + /* do we want a length word? */ + if (force_len || PG_PROTOCOL_MAJOR(conn->pversion) >= 3) + { + lenPos = endPos; + /* allow room for message length */ + endPos += 4; + } + else + lenPos = -1; + + /* make sure there is room for message header */ + if (pqCheckOutBufferSpace(endPos, conn)) + return EOF; + /* okay, save the message type byte if any */ + if (msg_type) + conn->outBuffer[conn->outCount] = msg_type; + /* set up the message pointers */ + conn->outMsgStart = lenPos; + conn->outMsgEnd = endPos; + /* length word, if needed, will be filled in by pqPutMsgEnd */ + + if (conn->Pfdebug) + fprintf(conn->Pfdebug, "To backend> Msg %c\n", + msg_type ? msg_type : ' '); + + return 0; +} + +/* + * pqPutMsgBytes: add bytes to a partially-constructed message + * + * Returns 0 on success, EOF on error + */ +static int +pqPutMsgBytes(const void *buf, size_t len, PGconn *conn) +{ + /* make sure there is room for it */ + if (pqCheckOutBufferSpace(conn->outMsgEnd + len, conn)) + return EOF; + /* okay, save the data */ + memcpy(conn->outBuffer + conn->outMsgEnd, buf, len); + conn->outMsgEnd += len; + /* no Pfdebug call here, caller should do it */ + return 0; +} + +/* + * pqPutMsgEnd: finish constructing a message and possibly send it + * + * Returns 0 on success, EOF on error + * + * We don't actually send anything here unless we've accumulated at least + * 8K worth of data (the typical size of a pipe buffer on Unix systems). + * This avoids sending small partial packets. The caller must use pqFlush + * when it's important to flush all the data out to the server. + */ +int +pqPutMsgEnd(PGconn *conn) +{ + if (conn->Pfdebug) + fprintf(conn->Pfdebug, "To backend> Msg complete, length %u\n", + conn->outMsgEnd - conn->outCount); + + /* Fill in length word if needed */ + if (conn->outMsgStart >= 0) + { + uint32 msgLen = conn->outMsgEnd - conn->outMsgStart; + + msgLen = htonl(msgLen); + memcpy(conn->outBuffer + conn->outMsgStart, &msgLen, 4); + } + + /* Make message eligible to send */ + conn->outCount = conn->outMsgEnd; + + if (conn->outCount >= 8192) + { + int toSend = conn->outCount - (conn->outCount % 8192); + + if (pqSendSome(conn, toSend) < 0) + return EOF; + /* in nonblock mode, don't complain if unable to send it all */ + } + + return 0; +} + +/* ---------- + * pqReadData: read more data, if any is available + * Possible return values: + * 1: successfully loaded at least one more byte + * 0: no data is presently available, but no error detected + * -1: error detected (including EOF = connection closure); + * conn->errorMessage set + * NOTE: callers must not assume that pointers or indexes into conn->inBuffer + * remain valid across this call! + * ---------- + */ +int +pqReadData(PGconn *conn) +{ + int someread = 0; + int nread; + + if (conn->sock == PGINVALID_SOCKET) + { + printfPQExpBuffer(&conn->errorMessage, + libpq_gettext("connection not open\n")); + return -1; + } + + /* Left-justify any data in the buffer to make room */ + if (conn->inStart < conn->inEnd) + { + if (conn->inStart > 0) + { + memmove(conn->inBuffer, conn->inBuffer + conn->inStart, + conn->inEnd - conn->inStart); + conn->inEnd -= conn->inStart; + conn->inCursor -= conn->inStart; + conn->inStart = 0; + } + } + else + { + /* buffer is logically empty, reset it */ + conn->inStart = conn->inCursor = conn->inEnd = 0; + } + + /* + * If the buffer is fairly full, enlarge it. We need to be able to enlarge + * the buffer in case a single message exceeds the initial buffer size. We + * enlarge before filling the buffer entirely so as to avoid asking the + * kernel for a partial packet. The magic constant here should be large + * enough for a TCP packet or Unix pipe bufferload. 8K is the usual pipe + * buffer size, so... + */ + if (conn->inBufSize - conn->inEnd < 8192) + { + if (pqCheckInBufferSpace(conn->inEnd + (size_t) 8192, conn)) + { + /* + * We don't insist that the enlarge worked, but we need some room + */ + if (conn->inBufSize - conn->inEnd < 100) + return -1; /* errorMessage already set */ + } + } + + /* OK, try to read some data */ +retry3: + nread = pqsecure_read(conn, conn->inBuffer + conn->inEnd, + conn->inBufSize - conn->inEnd); + if (nread < 0) + { + if (SOCK_ERRNO == EINTR) + goto retry3; + /* Some systems return EAGAIN/EWOULDBLOCK for no data */ +#ifdef EAGAIN + if (SOCK_ERRNO == EAGAIN) + return someread; +#endif +#if defined(EWOULDBLOCK) && (!defined(EAGAIN) || (EWOULDBLOCK != EAGAIN)) + if (SOCK_ERRNO == EWOULDBLOCK) + return someread; +#endif + /* We might get ECONNRESET here if using TCP and backend died */ +#ifdef ECONNRESET + if (SOCK_ERRNO == ECONNRESET) + goto definitelyFailed; +#endif + /* pqsecure_read set the error message for us */ + return -1; + } + if (nread > 0) + { + conn->inEnd += nread; + + /* + * Hack to deal with the fact that some kernels will only give us back + * 1 packet per recv() call, even if we asked for more and there is + * more available. If it looks like we are reading a long message, + * loop back to recv() again immediately, until we run out of data or + * buffer space. Without this, the block-and-restart behavior of + * libpq's higher levels leads to O(N^2) performance on long messages. + * + * Since we left-justified the data above, conn->inEnd gives the + * amount of data already read in the current message. We consider + * the message "long" once we have acquired 32k ... + */ + if (conn->inEnd > 32768 && + (conn->inBufSize - conn->inEnd) >= 8192) + { + someread = 1; + goto retry3; + } + return 1; + } + + if (someread) + return 1; /* got a zero read after successful tries */ + + /* + * A return value of 0 could mean just that no data is now available, or + * it could mean EOF --- that is, the server has closed the connection. + * Since we have the socket in nonblock mode, the only way to tell the + * difference is to see if select() is saying that the file is ready. + * Grumble. Fortunately, we don't expect this path to be taken much, + * since in normal practice we should not be trying to read data unless + * the file selected for reading already. + * + * In SSL mode it's even worse: SSL_read() could say WANT_READ and then + * data could arrive before we make the pqReadReady() test, but the second + * SSL_read() could still say WANT_READ because the data received was not + * a complete SSL record. So we must play dumb and assume there is more + * data, relying on the SSL layer to detect true EOF. + */ + +#ifdef USE_SSL + if (conn->ssl_in_use) + return 0; +#endif + + switch (pqReadReady(conn)) + { + case 0: + /* definitely no data available */ + return 0; + case 1: + /* ready for read */ + break; + default: + /* we override pqReadReady's message with something more useful */ + goto definitelyEOF; + } + + /* + * Still not sure that it's EOF, because some data could have just + * arrived. + */ +retry4: + nread = pqsecure_read(conn, conn->inBuffer + conn->inEnd, + conn->inBufSize - conn->inEnd); + if (nread < 0) + { + if (SOCK_ERRNO == EINTR) + goto retry4; + /* Some systems return EAGAIN/EWOULDBLOCK for no data */ +#ifdef EAGAIN + if (SOCK_ERRNO == EAGAIN) + return 0; +#endif +#if defined(EWOULDBLOCK) && (!defined(EAGAIN) || (EWOULDBLOCK != EAGAIN)) + if (SOCK_ERRNO == EWOULDBLOCK) + return 0; +#endif + /* We might get ECONNRESET here if using TCP and backend died */ +#ifdef ECONNRESET + if (SOCK_ERRNO == ECONNRESET) + goto definitelyFailed; +#endif + /* pqsecure_read set the error message for us */ + return -1; + } + if (nread > 0) + { + conn->inEnd += nread; + return 1; + } + + /* + * OK, we are getting a zero read even though select() says ready. This + * means the connection has been closed. Cope. + */ +definitelyEOF: + printfPQExpBuffer(&conn->errorMessage, + libpq_gettext( + "server closed the connection unexpectedly\n" + "\tThis probably means the server terminated abnormally\n" + "\tbefore or while processing the request.\n")); + + /* Come here if lower-level code already set a suitable errorMessage */ +definitelyFailed: + /* Do *not* drop any already-read data; caller still wants it */ + pqDropConnection(conn, false); + conn->status = CONNECTION_BAD; /* No more connection to backend */ + return -1; +} + +/* + * pqSendSome: send data waiting in the output buffer. + * + * len is how much to try to send (typically equal to outCount, but may + * be less). + * + * Return 0 on success, -1 on failure and 1 when not all data could be sent + * because the socket would block and the connection is non-blocking. + */ +static int +pqSendSome(PGconn *conn, int len) +{ + char *ptr = conn->outBuffer; + int remaining = conn->outCount; + int result = 0; + + if (conn->sock == PGINVALID_SOCKET) + { + printfPQExpBuffer(&conn->errorMessage, + libpq_gettext("connection not open\n")); + /* Discard queued data; no chance it'll ever be sent */ + conn->outCount = 0; + return -1; + } + + /* while there's still data to send */ + while (len > 0) + { + int sent; + +#ifndef WIN32 + sent = pqsecure_write(conn, ptr, len); +#else + + /* + * Windows can fail on large sends, per KB article Q201213. The + * failure-point appears to be different in different versions of + * Windows, but 64k should always be safe. + */ + sent = pqsecure_write(conn, ptr, Min(len, 65536)); +#endif + + if (sent < 0) + { + /* Anything except EAGAIN/EWOULDBLOCK/EINTR is trouble */ + switch (SOCK_ERRNO) + { +#ifdef EAGAIN + case EAGAIN: + break; +#endif +#if defined(EWOULDBLOCK) && (!defined(EAGAIN) || (EWOULDBLOCK != EAGAIN)) + case EWOULDBLOCK: + break; +#endif + case EINTR: + continue; + + default: + /* pqsecure_write set the error message for us */ + + /* + * We used to close the socket here, but that's a bad idea + * since there might be unread data waiting (typically, a + * NOTICE message from the backend telling us it's + * committing hara-kiri...). Leave the socket open until + * pqReadData finds no more data can be read. But abandon + * attempt to send data. + */ + conn->outCount = 0; + return -1; + } + } + else + { + ptr += sent; + len -= sent; + remaining -= sent; + } + + if (len > 0) + { + /* + * We didn't send it all, wait till we can send more. + * + * There are scenarios in which we can't send data because the + * communications channel is full, but we cannot expect the server + * to clear the channel eventually because it's blocked trying to + * send data to us. (This can happen when we are sending a large + * amount of COPY data, and the server has generated lots of + * NOTICE responses.) To avoid a deadlock situation, we must be + * prepared to accept and buffer incoming data before we try + * again. Furthermore, it is possible that such incoming data + * might not arrive until after we've gone to sleep. Therefore, + * we wait for either read ready or write ready. + * + * In non-blocking mode, we don't wait here directly, but return 1 + * to indicate that data is still pending. The caller should wait + * for both read and write ready conditions, and call + * PQconsumeInput() on read ready, but just in case it doesn't, we + * call pqReadData() ourselves before returning. That's not + * enough if the data has not arrived yet, but it's the best we + * can do, and works pretty well in practice. (The documentation + * used to say that you only need to wait for write-ready, so + * there are still plenty of applications like that out there.) + */ + if (pqReadData(conn) < 0) + { + result = -1; /* error message already set up */ + break; + } + + if (pqIsnonblocking(conn)) + { + result = 1; + break; + } + + if (pqWait(TRUE, TRUE, conn)) + { + result = -1; + break; + } + } + } + + /* shift the remaining contents of the buffer */ + if (remaining > 0) + memmove(conn->outBuffer, ptr, remaining); + conn->outCount = remaining; + + return result; +} + + +/* + * pqFlush: send any data waiting in the output buffer + * + * Return 0 on success, -1 on failure and 1 when not all data could be sent + * because the socket would block and the connection is non-blocking. + */ +int +pqFlush(PGconn *conn) +{ + if (conn->Pfdebug) + fflush(conn->Pfdebug); + + if (conn->outCount > 0) + return pqSendSome(conn, conn->outCount); + + return 0; +} + + +/* + * pqWait: wait until we can read or write the connection socket + * + * JAB: If SSL enabled and used and forRead, buffered bytes short-circuit the + * call to select(). + * + * We also stop waiting and return if the kernel flags an exception condition + * on the socket. The actual error condition will be detected and reported + * when the caller tries to read or write the socket. + */ +int +pqWait(int forRead, int forWrite, PGconn *conn) +{ + return pqWaitTimed(forRead, forWrite, conn, (time_t) -1); +} + +/* + * pqWaitTimed: wait, but not past finish_time. + * + * If finish_time is exceeded then we return failure (EOF). This is like + * the response for a kernel exception because we don't want the caller + * to try to read/write in that case. + * + * finish_time = ((time_t) -1) disables the wait limit. + */ +int +pqWaitTimed(int forRead, int forWrite, PGconn *conn, time_t finish_time) +{ + int result; + + result = pqSocketCheck(conn, forRead, forWrite, finish_time); + + if (result < 0) + return EOF; /* errorMessage is already set */ + + if (result == 0) + { + printfPQExpBuffer(&conn->errorMessage, + libpq_gettext("timeout expired\n")); + return EOF; + } + + return 0; +} + +/* + * pqReadReady: is select() saying the file is ready to read? + * Returns -1 on failure, 0 if not ready, 1 if ready. + */ +int +pqReadReady(PGconn *conn) +{ + return pqSocketCheck(conn, 1, 0, (time_t) 0); +} + +/* + * pqWriteReady: is select() saying the file is ready to write? + * Returns -1 on failure, 0 if not ready, 1 if ready. + */ +int +pqWriteReady(PGconn *conn) +{ + return pqSocketCheck(conn, 0, 1, (time_t) 0); +} + +/* + * Checks a socket, using poll or select, for data to be read, written, + * or both. Returns >0 if one or more conditions are met, 0 if it timed + * out, -1 if an error occurred. + * + * If SSL is in use, the SSL buffer is checked prior to checking the socket + * for read data directly. + */ +static int +pqSocketCheck(PGconn *conn, int forRead, int forWrite, time_t end_time) +{ + int result; + + if (!conn) + return -1; + if (conn->sock == PGINVALID_SOCKET) + { + printfPQExpBuffer(&conn->errorMessage, + libpq_gettext("invalid socket\n")); + return -1; + } + +#ifdef USE_SSL + /* Check for SSL library buffering read bytes */ + if (forRead && conn->ssl_in_use && pgtls_read_pending(conn) > 0) + { + /* short-circuit the select */ + return 1; + } +#endif + + /* We will retry as long as we get EINTR */ + do + result = pqSocketPoll(conn->sock, forRead, forWrite, end_time); + while (result < 0 && SOCK_ERRNO == EINTR); + + if (result < 0) + { + char sebuf[256]; + + printfPQExpBuffer(&conn->errorMessage, + libpq_gettext("select() failed: %s\n"), + SOCK_STRERROR(SOCK_ERRNO, sebuf, sizeof(sebuf))); + } + + return result; +} + + +/* + * Check a file descriptor for read and/or write data, possibly waiting. + * If neither forRead nor forWrite are set, immediately return a timeout + * condition (without waiting). Return >0 if condition is met, 0 + * if a timeout occurred, -1 if an error or interrupt occurred. + * + * Timeout is infinite if end_time is -1. Timeout is immediate (no blocking) + * if end_time is 0 (or indeed, any time before now). + */ +static int +pqSocketPoll(int sock, int forRead, int forWrite, time_t end_time) +{ + /* We use poll(2) if available, otherwise select(2) */ +#ifdef HAVE_POLL + struct pollfd input_fd; + int timeout_ms; + + if (!forRead && !forWrite) + return 0; + + input_fd.fd = sock; + input_fd.events = POLLERR; + input_fd.revents = 0; + + if (forRead) + input_fd.events |= POLLIN; + if (forWrite) + input_fd.events |= POLLOUT; + + /* Compute appropriate timeout interval */ + if (end_time == ((time_t) -1)) + timeout_ms = -1; + else + { + time_t now = time(NULL); + + if (end_time > now) + timeout_ms = (end_time - now) * 1000; + else + timeout_ms = 0; + } + + return poll(&input_fd, 1, timeout_ms); +#else /* !HAVE_POLL */ + + fd_set input_mask; + fd_set output_mask; + fd_set except_mask; + struct timeval timeout; + struct timeval *ptr_timeout; + + if (!forRead && !forWrite) + return 0; + + FD_ZERO(&input_mask); + FD_ZERO(&output_mask); + FD_ZERO(&except_mask); + if (forRead) + FD_SET(sock, &input_mask); + + if (forWrite) + FD_SET(sock, &output_mask); + FD_SET(sock, &except_mask); + + /* Compute appropriate timeout interval */ + if (end_time == ((time_t) -1)) + ptr_timeout = NULL; + else + { + time_t now = time(NULL); + + if (end_time > now) + timeout.tv_sec = end_time - now; + else + timeout.tv_sec = 0; + timeout.tv_usec = 0; + ptr_timeout = &timeout; + } + + return select(sock + 1, &input_mask, &output_mask, + &except_mask, ptr_timeout); +#endif /* HAVE_POLL */ +} + + +/* + * A couple of "miscellaneous" multibyte related functions. They used + * to be in fe-print.c but that file is doomed. + */ + +/* + * returns the byte length of the character beginning at s, using the + * specified encoding. + */ +int +PQmblen(const char *s, int encoding) +{ + return pg_encoding_mblen(encoding, s); +} + +/* + * returns the display length of the character beginning at s, using the + * specified encoding. + */ +int +PQdsplen(const char *s, int encoding) +{ + return pg_encoding_dsplen(encoding, s); +} + +/* + * Get encoding id from environment variable PGCLIENTENCODING. + */ +int +PQenv2encoding(void) +{ + char *str; + int encoding = PG_SQL_ASCII; + + str = getenv("PGCLIENTENCODING"); + if (str && *str != '\0') + { + encoding = pg_char_to_encoding(str); + if (encoding < 0) + encoding = PG_SQL_ASCII; + } + return encoding; +} + + +#ifdef ENABLE_NLS + +static void +libpq_binddomain() +{ + static bool already_bound = false; + + if (!already_bound) + { + /* bindtextdomain() does not preserve errno */ +#ifdef WIN32 + int save_errno = GetLastError(); +#else + int save_errno = errno; +#endif + const char *ldir; + + already_bound = true; + /* No relocatable lookup here because the binary could be anywhere */ + ldir = getenv("PGLOCALEDIR"); + if (!ldir) + ldir = LOCALEDIR; + bindtextdomain(PG_TEXTDOMAIN("libpq"), ldir); +#ifdef WIN32 + SetLastError(save_errno); +#else + errno = save_errno; +#endif + } +} + +char * +libpq_gettext(const char *msgid) +{ + libpq_binddomain(); + return dgettext(PG_TEXTDOMAIN("libpq"), msgid); +} + +char * +libpq_ngettext(const char *msgid, const char *msgid_plural, unsigned long n) +{ + libpq_binddomain(); + return dngettext(PG_TEXTDOMAIN("libpq"), msgid, msgid_plural, n); +} + +#endif /* ENABLE_NLS */ |