fe-trace.c

Go to the documentation of this file.

/*-------------------------------------------------------------------------
 *
 *  fe-trace.c
 *    functions for libpq protocol tracing
 *
 * Portions Copyright (c) 1996-2026, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 * IDENTIFICATION
 *    src/interfaces/libpq/fe-trace.c
 *
 *-------------------------------------------------------------------------
 */
 
#include "postgres_fe.h"
 
#include <ctype.h>
#include <limits.h>
#include <sys/time.h>
#include <time.h>
 
#ifdef WIN32
#include "win32.h"
#else
#include <unistd.h>
#endif
 
#include "libpq-fe.h"
#include "libpq-int.h"
#include "port/pg_bswap.h"
 
 
/* Enable tracing */
void
PQtrace(PGconn *conn, FILE *debug_port)
{
    if (conn == NULL)
        return;
    PQuntrace(conn);
    if (debug_port == NULL)
        return;
 
    conn->Pfdebug = debug_port;
    conn->traceFlags = 0;
}
 
/* Disable tracing */
void
PQuntrace(PGconn *conn)
{
    if (conn == NULL)
        return;
    if (conn->Pfdebug)
    {
        fflush(conn->Pfdebug);
        conn->Pfdebug = NULL;
    }
 
    conn->traceFlags = 0;
}
 
/* Set flags for current tracing session */
void
PQsetTraceFlags(PGconn *conn, int flags)
{
    if (conn == NULL)
        return;
    /* If PQtrace() failed, do nothing. */
    if (conn->Pfdebug == NULL)
        return;
    conn->traceFlags = flags;
}
 
/*
 * Print the current time, with microseconds, into a caller-supplied
 * buffer.
 * Cribbed from get_formatted_log_time, but much simpler.
 */
static void
pqTraceFormatTimestamp(char *timestr, size_t ts_len)
{
    struct timeval tval;
    time_t      now;
    struct tm   tmbuf;
 
    gettimeofday(&tval, NULL);
 
    /*
     * MSVC's implementation of timeval uses a long for tv_sec, however,
     * localtime() expects a time_t pointer.  Here we'll assign tv_sec to a
     * local time_t variable so that we pass localtime() the correct pointer
     * type.
     */
    now = tval.tv_sec;
    strftime(timestr, ts_len,
             "%Y-%m-%d %H:%M:%S",
             localtime_r(&now, &tmbuf));
    /* append microseconds */
    snprintf(timestr + strlen(timestr), ts_len - strlen(timestr),
             ".%06u", (unsigned int) (tval.tv_usec));
}
 
/*
 *   pqTraceOutputByte1: output a 1-char message to the log
 */
static void
pqTraceOutputByte1(FILE *pfdebug, const char *data, int *cursor)
{
    const char *v = data + *cursor;
 
    /*
     * Show non-printable data in hex format, including the terminating \0
     * that completes ErrorResponse and NoticeResponse messages.
     */
    if (!isprint((unsigned char) *v))
        fprintf(pfdebug, " \\x%02x", (unsigned char) *v);
    else
        fprintf(pfdebug, " %c", *v);
    *cursor += 1;
}
 
/*
 *   pqTraceOutputInt16: output a 2-byte integer message to the log
 */
static int
pqTraceOutputInt16(FILE *pfdebug, const char *data, int *cursor)
{
    uint16      tmp;
    int         result;
 
    memcpy(&tmp, data + *cursor, 2);
    *cursor += 2;
    result = (int) pg_ntoh16(tmp);
    fprintf(pfdebug, " %d", result);
 
    return result;
}
 
/*
 *   pqTraceOutputInt32: output a 4-byte integer message to the log
 *
 * If 'suppress' is true, print a literal NNNN instead of the actual number.
 */
static int
pqTraceOutputInt32(FILE *pfdebug, const char *data, int *cursor, bool suppress)
{
    int         result;
 
    memcpy(&result, data + *cursor, 4);
    *cursor += 4;
    result = (int) pg_ntoh32(result);
    if (suppress)
        fprintf(pfdebug, " NNNN");
    else
        fprintf(pfdebug, " %d", result);
 
    return result;
}
 
/*
 *   pqTraceOutputString: output a string message to the log
 *
 * If 'suppress' is true, print a literal "SSSS" instead of the actual string.
 */
static void
pqTraceOutputString(FILE *pfdebug, const char *data, int *cursor, bool suppress)
{
    int         len;
 
    if (suppress)
    {
        fprintf(pfdebug, " \"SSSS\"");
        *cursor += strlen(data + *cursor) + 1;
    }
    else
    {
        len = fprintf(pfdebug, " \"%s\"", data + *cursor);
 
        /*
         * This is a null-terminated string. So add 1 after subtracting 3
         * which is the double quotes and space length from len.
         */
        *cursor += (len - 3 + 1);
    }
}
 
/*
 * pqTraceOutputNchar: output a string of exactly len bytes message to the log
 *
 * If 'suppress' is true, print a literal 'BBBB' instead of the actual bytes.
 */
static void
pqTraceOutputNchar(FILE *pfdebug, int len, const char *data, int *cursor, bool suppress)
{
    int         i,
                next;           /* first char not yet printed */
    const char *v = data + *cursor;
 
    if (suppress)
    {
        fprintf(pfdebug, " 'BBBB'");
        *cursor += len;
        return;
    }
 
    fprintf(pfdebug, " \'");
 
    for (next = i = 0; i < len; ++i)
    {
        if (isprint((unsigned char) v[i]))
            continue;
        else
        {
            fwrite(v + next, 1, i - next, pfdebug);
            fprintf(pfdebug, "\\x%02x", (unsigned char) v[i]);
            next = i + 1;
        }
    }
    if (next < len)
        fwrite(v + next, 1, len - next, pfdebug);
 
    fprintf(pfdebug, "\'");
    *cursor += len;
}
 
/*
 * Output functions by protocol message type
 */
 
static void
pqTraceOutput_NotificationResponse(FILE *f, const char *message, int *cursor, bool regress)
{
    fprintf(f, "NotificationResponse\t");
    pqTraceOutputInt32(f, message, cursor, regress);
    pqTraceOutputString(f, message, cursor, false);
    pqTraceOutputString(f, message, cursor, false);
}
 
static void
pqTraceOutput_Bind(FILE *f, const char *message, int *cursor)
{
    int         nparams;
 
    fprintf(f, "Bind\t");
    pqTraceOutputString(f, message, cursor, false);
    pqTraceOutputString(f, message, cursor, false);
    nparams = pqTraceOutputInt16(f, message, cursor);
 
    for (int i = 0; i < nparams; i++)
        pqTraceOutputInt16(f, message, cursor);
 
    nparams = pqTraceOutputInt16(f, message, cursor);
 
    for (int i = 0; i < nparams; i++)
    {
        int         nbytes;
 
        nbytes = pqTraceOutputInt32(f, message, cursor, false);
        if (nbytes == -1)
            continue;
        pqTraceOutputNchar(f, nbytes, message, cursor, false);
    }
 
    nparams = pqTraceOutputInt16(f, message, cursor);
    for (int i = 0; i < nparams; i++)
        pqTraceOutputInt16(f, message, cursor);
}
 
static void
pqTraceOutput_Close(FILE *f, const char *message, int *cursor)
{
    fprintf(f, "Close\t");
    pqTraceOutputByte1(f, message, cursor);
    pqTraceOutputString(f, message, cursor, false);
}
 
static void
pqTraceOutput_CommandComplete(FILE *f, const char *message, int *cursor)
{
    fprintf(f, "CommandComplete\t");
    pqTraceOutputString(f, message, cursor, false);
}
 
static void
pqTraceOutput_CopyData(FILE *f, const char *message, int *cursor, int length,
                       bool suppress)
{
    fprintf(f, "CopyData\t");
    pqTraceOutputNchar(f, length - *cursor + 1, message, cursor, suppress);
}
 
static void
pqTraceOutput_DataRow(FILE *f, const char *message, int *cursor)
{
    int         nfields;
    int         len;
    int         i;
 
    fprintf(f, "DataRow\t");
    nfields = pqTraceOutputInt16(f, message, cursor);
    for (i = 0; i < nfields; i++)
    {
        len = pqTraceOutputInt32(f, message, cursor, false);
        if (len == -1)
            continue;
        pqTraceOutputNchar(f, len, message, cursor, false);
    }
}
 
static void
pqTraceOutput_Describe(FILE *f, const char *message, int *cursor)
{
    fprintf(f, "Describe\t");
    pqTraceOutputByte1(f, message, cursor);
    pqTraceOutputString(f, message, cursor, false);
}
 
/* shared code NoticeResponse / ErrorResponse */
static void
pqTraceOutputNR(FILE *f, const char *type, const char *message, int *cursor,
                bool regress)
{
    fprintf(f, "%s\t", type);
    for (;;)
    {
        char        field;
        bool        suppress;
 
        pqTraceOutputByte1(f, message, cursor);
        field = message[*cursor - 1];
        if (field == '\0')
            break;
 
        suppress = regress && (field == 'L' || field == 'F' || field == 'R');
        pqTraceOutputString(f, message, cursor, suppress);
    }
}
 
static void
pqTraceOutput_ErrorResponse(FILE *f, const char *message, int *cursor, bool regress)
{
    pqTraceOutputNR(f, "ErrorResponse", message, cursor, regress);
}
 
static void
pqTraceOutput_NoticeResponse(FILE *f, const char *message, int *cursor, bool regress)
{
    pqTraceOutputNR(f, "NoticeResponse", message, cursor, regress);
}
 
static void
pqTraceOutput_Execute(FILE *f, const char *message, int *cursor, bool regress)
{
    fprintf(f, "Execute\t");
    pqTraceOutputString(f, message, cursor, false);
    pqTraceOutputInt32(f, message, cursor, false);
}
 
static void
pqTraceOutput_CopyFail(FILE *f, const char *message, int *cursor)
{
    fprintf(f, "CopyFail\t");
    pqTraceOutputString(f, message, cursor, false);
}
 
static void
pqTraceOutput_GSSResponse(FILE *f, const char *message, int *cursor,
                          int length, bool regress)
{
    fprintf(f, "GSSResponse\t");
    pqTraceOutputNchar(f, length - *cursor + 1, message, cursor, regress);
}
 
static void
pqTraceOutput_PasswordMessage(FILE *f, const char *message, int *cursor)
{
    fprintf(f, "PasswordMessage\t");
    pqTraceOutputString(f, message, cursor, false);
}
 
static void
pqTraceOutput_SASLInitialResponse(FILE *f, const char *message, int *cursor,
                                  bool regress)
{
    int         initialResponse;
 
    fprintf(f, "SASLInitialResponse\t");
    pqTraceOutputString(f, message, cursor, false);
    initialResponse = pqTraceOutputInt32(f, message, cursor, false);
    if (initialResponse != -1)
        pqTraceOutputNchar(f, initialResponse, message, cursor, regress);
}
 
static void
pqTraceOutput_SASLResponse(FILE *f, const char *message, int *cursor,
                           int length, bool regress)
{
    fprintf(f, "SASLResponse\t");
    pqTraceOutputNchar(f, length - *cursor + 1, message, cursor, regress);
}
 
static void
pqTraceOutput_FunctionCall(FILE *f, const char *message, int *cursor, bool regress)
{
    int         nfields;
    int         nbytes;
 
    fprintf(f, "FunctionCall\t");
    pqTraceOutputInt32(f, message, cursor, regress);
    nfields = pqTraceOutputInt16(f, message, cursor);
 
    for (int i = 0; i < nfields; i++)
        pqTraceOutputInt16(f, message, cursor);
 
    nfields = pqTraceOutputInt16(f, message, cursor);
 
    for (int i = 0; i < nfields; i++)
    {
        nbytes = pqTraceOutputInt32(f, message, cursor, false);
        if (nbytes == -1)
            continue;
        pqTraceOutputNchar(f, nbytes, message, cursor, false);
    }
 
    pqTraceOutputInt16(f, message, cursor);
}
 
static void
pqTraceOutput_CopyInResponse(FILE *f, const char *message, int *cursor)
{
    int         nfields;
 
    fprintf(f, "CopyInResponse\t");
    pqTraceOutputByte1(f, message, cursor);
    nfields = pqTraceOutputInt16(f, message, cursor);
 
    for (int i = 0; i < nfields; i++)
        pqTraceOutputInt16(f, message, cursor);
}
 
static void
pqTraceOutput_CopyOutResponse(FILE *f, const char *message, int *cursor)
{
    int         nfields;
 
    fprintf(f, "CopyOutResponse\t");
    pqTraceOutputByte1(f, message, cursor);
    nfields = pqTraceOutputInt16(f, message, cursor);
 
    for (int i = 0; i < nfields; i++)
        pqTraceOutputInt16(f, message, cursor);
}
 
static void
pqTraceOutput_BackendKeyData(FILE *f, const char *message, int *cursor, int length,
                             bool regress)
{
    fprintf(f, "BackendKeyData\t");
    pqTraceOutputInt32(f, message, cursor, regress);
    pqTraceOutputNchar(f, length - *cursor + 1, message, cursor, regress);
}
 
static void
pqTraceOutput_Parse(FILE *f, const char *message, int *cursor, bool regress)
{
    int         nparams;
 
    fprintf(f, "Parse\t");
    pqTraceOutputString(f, message, cursor, false);
    pqTraceOutputString(f, message, cursor, false);
    nparams = pqTraceOutputInt16(f, message, cursor);
 
    for (int i = 0; i < nparams; i++)
        pqTraceOutputInt32(f, message, cursor, regress);
}
 
static void
pqTraceOutput_Query(FILE *f, const char *message, int *cursor)
{
    fprintf(f, "Query\t");
    pqTraceOutputString(f, message, cursor, false);
}
 
static void
pqTraceOutput_Authentication(FILE *f, const char *message, int *cursor,
                             int length, bool suppress)
{
    int         authType = 0;
 
    memcpy(&authType, message + *cursor, 4);
    authType = (int) pg_ntoh32(authType);
    *cursor += 4;
    switch (authType)
    {
        case AUTH_REQ_OK:
            fprintf(f, "AuthenticationOk");
            break;
            /* AUTH_REQ_KRB4 not supported */
            /* AUTH_REQ_KRB5 not supported */
        case AUTH_REQ_PASSWORD:
            fprintf(f, "AuthenticationCleartextPassword");
            break;
            /* AUTH_REQ_CRYPT not supported */
        case AUTH_REQ_MD5:
            fprintf(f, "AuthenticationMD5Password");
            break;
        case AUTH_REQ_GSS:
            fprintf(f, "AuthenticationGSS");
            break;
        case AUTH_REQ_GSS_CONT:
            fprintf(f, "AuthenticationGSSContinue\t");
            pqTraceOutputNchar(f, length - *cursor + 1, message, cursor,
                               suppress);
            break;
        case AUTH_REQ_SSPI:
            fprintf(f, "AuthenticationSSPI");
            break;
        case AUTH_REQ_SASL:
            fprintf(f, "AuthenticationSASL\t");
            while (message[*cursor] != '\0')
                pqTraceOutputString(f, message, cursor, false);
            pqTraceOutputString(f, message, cursor, false);
            break;
        case AUTH_REQ_SASL_CONT:
            fprintf(f, "AuthenticationSASLContinue\t");
            pqTraceOutputNchar(f, length - *cursor + 1, message, cursor,
                               suppress);
            break;
        case AUTH_REQ_SASL_FIN:
            fprintf(f, "AuthenticationSASLFinal\t");
            pqTraceOutputNchar(f, length - *cursor + 1, message, cursor,
                               suppress);
            break;
        default:
            fprintf(f, "Unknown authentication message %d", authType);
    }
}
 
static void
pqTraceOutput_ParameterStatus(FILE *f, const char *message, int *cursor)
{
    fprintf(f, "ParameterStatus\t");
    pqTraceOutputString(f, message, cursor, false);
    pqTraceOutputString(f, message, cursor, false);
}
 
static void
pqTraceOutput_ParameterDescription(FILE *f, const char *message, int *cursor, bool regress)
{
    int         nfields;
 
    fprintf(f, "ParameterDescription\t");
    nfields = pqTraceOutputInt16(f, message, cursor);
 
    for (int i = 0; i < nfields; i++)
        pqTraceOutputInt32(f, message, cursor, regress);
}
 
static void
pqTraceOutput_RowDescription(FILE *f, const char *message, int *cursor, bool regress)
{
    int         nfields;
 
    fprintf(f, "RowDescription\t");
    nfields = pqTraceOutputInt16(f, message, cursor);
 
    for (int i = 0; i < nfields; i++)
    {
        pqTraceOutputString(f, message, cursor, false);
        pqTraceOutputInt32(f, message, cursor, regress);
        pqTraceOutputInt16(f, message, cursor);
        pqTraceOutputInt32(f, message, cursor, regress);
        pqTraceOutputInt16(f, message, cursor);
        pqTraceOutputInt32(f, message, cursor, false);
        pqTraceOutputInt16(f, message, cursor);
    }
}
 
static void
pqTraceOutput_NegotiateProtocolVersion(FILE *f, const char *message, int *cursor)
{
    int         nparams;
 
    fprintf(f, "NegotiateProtocolVersion\t");
    pqTraceOutputInt32(f, message, cursor, false);
    nparams = pqTraceOutputInt32(f, message, cursor, false);
    for (int i = 0; i < nparams; i++)
    {
        pqTraceOutputString(f, message, cursor, false);
    }
}
 
static void
pqTraceOutput_FunctionCallResponse(FILE *f, const char *message, int *cursor)
{
    int         len;
 
    fprintf(f, "FunctionCallResponse\t");
    len = pqTraceOutputInt32(f, message, cursor, false);
    if (len != -1)
        pqTraceOutputNchar(f, len, message, cursor, false);
}
 
static void
pqTraceOutput_CopyBothResponse(FILE *f, const char *message, int *cursor, int length)
{
    fprintf(f, "CopyBothResponse\t");
    pqTraceOutputByte1(f, message, cursor);
 
    while (length > *cursor)
        pqTraceOutputInt16(f, message, cursor);
}
 
static void
pqTraceOutput_ReadyForQuery(FILE *f, const char *message, int *cursor)
{
    fprintf(f, "ReadyForQuery\t");
    pqTraceOutputByte1(f, message, cursor);
}
 
/*
 * Print the given message to the trace output stream.
 */
void
pqTraceOutputMessage(PGconn *conn, const char *message, bool toServer)
{
    char        id;
    int         length;
    char       *prefix = toServer ? "F" : "B";
    int         logCursor = 0;
    bool        regress;
 
    if ((conn->traceFlags & PQTRACE_SUPPRESS_TIMESTAMPS) == 0)
    {
        char        timestr[128];
 
        pqTraceFormatTimestamp(timestr, sizeof(timestr));
        fprintf(conn->Pfdebug, "%s\t", timestr);
    }
    regress = (conn->traceFlags & PQTRACE_REGRESS_MODE) != 0;
 
    id = message[logCursor++];
 
    memcpy(&length, message + logCursor, 4);
    length = (int) pg_ntoh32(length);
    logCursor += 4;
 
    /*
     * In regress mode, suppress the length of ErrorResponse and
     * NoticeResponse.  The F (file name), L (line number) and R (routine
     * name) fields can change as server code is modified, and if their
     * lengths differ from the originals, that would break tests.
     */
    if (regress && !toServer && (id == PqMsg_ErrorResponse || id == PqMsg_NoticeResponse))
        fprintf(conn->Pfdebug, "%s\tNN\t", prefix);
    else
        fprintf(conn->Pfdebug, "%s\t%d\t", prefix, length);
 
    switch (id)
    {
        case PqMsg_ParseComplete:
            fprintf(conn->Pfdebug, "ParseComplete");
            /* No message content */
            break;
        case PqMsg_BindComplete:
            fprintf(conn->Pfdebug, "BindComplete");
            /* No message content */
            break;
        case PqMsg_CloseComplete:
            fprintf(conn->Pfdebug, "CloseComplete");
            /* No message content */
            break;
        case PqMsg_NotificationResponse:
            pqTraceOutput_NotificationResponse(conn->Pfdebug, message, &logCursor, regress);
            break;
        case PqMsg_Bind:
            pqTraceOutput_Bind(conn->Pfdebug, message, &logCursor);
            break;
        case PqMsg_CopyDone:
            fprintf(conn->Pfdebug, "CopyDone");
            /* No message content */
            break;
        case PqMsg_CommandComplete:
            /* Close(F) and CommandComplete(B) use the same identifier. */
            Assert(PqMsg_Close == PqMsg_CommandComplete);
            if (toServer)
                pqTraceOutput_Close(conn->Pfdebug, message, &logCursor);
            else
                pqTraceOutput_CommandComplete(conn->Pfdebug, message, &logCursor);
            break;
        case PqMsg_CopyData:
            pqTraceOutput_CopyData(conn->Pfdebug, message, &logCursor,
                                   length, regress);
            break;
        case PqMsg_Describe:
            /* Describe(F) and DataRow(B) use the same identifier. */
            Assert(PqMsg_Describe == PqMsg_DataRow);
            if (toServer)
                pqTraceOutput_Describe(conn->Pfdebug, message, &logCursor);
            else
                pqTraceOutput_DataRow(conn->Pfdebug, message, &logCursor);
            break;
        case PqMsg_Execute:
            /* Execute(F) and ErrorResponse(B) use the same identifier. */
            Assert(PqMsg_Execute == PqMsg_ErrorResponse);
            if (toServer)
                pqTraceOutput_Execute(conn->Pfdebug, message, &logCursor, regress);
            else
                pqTraceOutput_ErrorResponse(conn->Pfdebug, message, &logCursor, regress);
            break;
        case PqMsg_CopyFail:
            pqTraceOutput_CopyFail(conn->Pfdebug, message, &logCursor);
            break;
        case PqMsg_GSSResponse:
            Assert(PqMsg_GSSResponse == PqMsg_PasswordMessage);
            Assert(PqMsg_GSSResponse == PqMsg_SASLInitialResponse);
            Assert(PqMsg_GSSResponse == PqMsg_SASLResponse);
 
            /*
             * These messages share a common type byte, so we discriminate by
             * having the code store the auth type separately.
             */
            switch (conn->current_auth_response)
            {
                case AUTH_RESPONSE_GSS:
                    pqTraceOutput_GSSResponse(conn->Pfdebug, message,
                                              &logCursor, length, regress);
                    break;
                case AUTH_RESPONSE_PASSWORD:
                    pqTraceOutput_PasswordMessage(conn->Pfdebug, message,
                                                  &logCursor);
                    break;
                case AUTH_RESPONSE_SASL_INITIAL:
                    pqTraceOutput_SASLInitialResponse(conn->Pfdebug, message,
                                                      &logCursor, regress);
                    break;
                case AUTH_RESPONSE_SASL:
                    pqTraceOutput_SASLResponse(conn->Pfdebug, message,
                                               &logCursor, length, regress);
                    break;
                default:
                    fprintf(conn->Pfdebug, "UnknownAuthenticationResponse");
                    break;
            }
            conn->current_auth_response = '\0';
            break;
        case PqMsg_FunctionCall:
            pqTraceOutput_FunctionCall(conn->Pfdebug, message, &logCursor, regress);
            break;
        case PqMsg_CopyInResponse:
            pqTraceOutput_CopyInResponse(conn->Pfdebug, message, &logCursor);
            break;
        case PqMsg_Flush:
            /* Flush(F) and CopyOutResponse(B) use the same identifier */
            Assert(PqMsg_CopyOutResponse == PqMsg_Flush);
            if (toServer)
                fprintf(conn->Pfdebug, "Flush");    /* no message content */
            else
                pqTraceOutput_CopyOutResponse(conn->Pfdebug, message, &logCursor);
            break;
        case PqMsg_EmptyQueryResponse:
            fprintf(conn->Pfdebug, "EmptyQueryResponse");
            /* No message content */
            break;
        case PqMsg_BackendKeyData:
            pqTraceOutput_BackendKeyData(conn->Pfdebug, message, &logCursor,
                                         length, regress);
            break;
        case PqMsg_NoData:
            fprintf(conn->Pfdebug, "NoData");
            /* No message content */
            break;
        case PqMsg_NoticeResponse:
            pqTraceOutput_NoticeResponse(conn->Pfdebug, message, &logCursor, regress);
            break;
        case PqMsg_Parse:
            pqTraceOutput_Parse(conn->Pfdebug, message, &logCursor, regress);
            break;
        case PqMsg_Query:
            pqTraceOutput_Query(conn->Pfdebug, message, &logCursor);
            break;
        case PqMsg_AuthenticationRequest:
            pqTraceOutput_Authentication(conn->Pfdebug, message, &logCursor,
                                         length, regress);
            break;
        case PqMsg_PortalSuspended:
            fprintf(conn->Pfdebug, "PortalSuspended");
            /* No message content */
            break;
        case PqMsg_Sync:
            /* ParameterStatus(B) and Sync(F) use the same identifier */
            Assert(PqMsg_ParameterStatus == PqMsg_Sync);
            if (toServer)
                fprintf(conn->Pfdebug, "Sync"); /* no message content */
            else
                pqTraceOutput_ParameterStatus(conn->Pfdebug, message, &logCursor);
            break;
        case PqMsg_ParameterDescription:
            pqTraceOutput_ParameterDescription(conn->Pfdebug, message, &logCursor, regress);
            break;
        case PqMsg_RowDescription:
            pqTraceOutput_RowDescription(conn->Pfdebug, message, &logCursor, regress);
            break;
        case PqMsg_NegotiateProtocolVersion:
            pqTraceOutput_NegotiateProtocolVersion(conn->Pfdebug, message, &logCursor);
            break;
        case PqMsg_FunctionCallResponse:
            pqTraceOutput_FunctionCallResponse(conn->Pfdebug, message, &logCursor);
            break;
        case PqMsg_CopyBothResponse:
            pqTraceOutput_CopyBothResponse(conn->Pfdebug, message, &logCursor, length);
            break;
        case PqMsg_Terminate:
            fprintf(conn->Pfdebug, "Terminate");
            /* No message content */
            break;
        case PqMsg_ReadyForQuery:
            pqTraceOutput_ReadyForQuery(conn->Pfdebug, message, &logCursor);
            break;
        default:
            fprintf(conn->Pfdebug, "Unknown message: %02x", id);
            break;
    }
 
    fputc('\n', conn->Pfdebug);
 
    /*
     * Verify the printing routine did it right.  Note that the one-byte
     * message identifier is not included in the length, but our cursor does
     * include it.
     */
    if (logCursor - 1 != length)
        fprintf(conn->Pfdebug,
                "mismatched message length: consumed %d, expected %d\n",
                logCursor - 1, length);
}
 
/*
 * Print special messages (those containing no type byte) to the trace output
 * stream.
 */
void
pqTraceOutputNoTypeByteMessage(PGconn *conn, const char *message)
{
    int         length;
    int         version;
    bool        regress;
    int         logCursor = 0;
 
    regress = (conn->traceFlags & PQTRACE_REGRESS_MODE) != 0;
 
    if ((conn->traceFlags & PQTRACE_SUPPRESS_TIMESTAMPS) == 0)
    {
        char        timestr[128];
 
        pqTraceFormatTimestamp(timestr, sizeof(timestr));
        fprintf(conn->Pfdebug, "%s\t", timestr);
    }
 
    memcpy(&length, message + logCursor, 4);
    length = (int) pg_ntoh32(length);
    logCursor += 4;
 
    fprintf(conn->Pfdebug, "F\t%d\t", length);
 
    if (length < 8)
    {
        fprintf(conn->Pfdebug, "Unknown message\n");
        return;
    }
 
    memcpy(&version, message + logCursor, 4);
    version = (int) pg_ntoh32(version);
 
    if (version == CANCEL_REQUEST_CODE && length >= 16)
    {
        fprintf(conn->Pfdebug, "CancelRequest\t");
        pqTraceOutputInt16(conn->Pfdebug, message, &logCursor);
        pqTraceOutputInt16(conn->Pfdebug, message, &logCursor);
        pqTraceOutputInt32(conn->Pfdebug, message, &logCursor, regress);
        pqTraceOutputNchar(conn->Pfdebug, length - logCursor, message,
                           &logCursor, regress);
    }
    else if (version == NEGOTIATE_SSL_CODE)
    {
        fprintf(conn->Pfdebug, "SSLRequest\t");
        pqTraceOutputInt16(conn->Pfdebug, message, &logCursor);
        pqTraceOutputInt16(conn->Pfdebug, message, &logCursor);
    }
    else if (version == NEGOTIATE_GSS_CODE)
    {
        fprintf(conn->Pfdebug, "GSSENCRequest\t");
        pqTraceOutputInt16(conn->Pfdebug, message, &logCursor);
        pqTraceOutputInt16(conn->Pfdebug, message, &logCursor);
    }
    else
    {
        fprintf(conn->Pfdebug, "StartupMessage\t");
        pqTraceOutputInt16(conn->Pfdebug, message, &logCursor);
        pqTraceOutputInt16(conn->Pfdebug, message, &logCursor);
        while (message[logCursor] != '\0')
        {
            /* XXX should we suppress anything in regress mode? */
            pqTraceOutputString(conn->Pfdebug, message, &logCursor, false);
            pqTraceOutputString(conn->Pfdebug, message, &logCursor, false);
        }
    }
 
    fputc('\n', conn->Pfdebug);
}
 
/*
 * Trace a single-byte backend response received for a known request
 * type the frontend previously sent.  Only useful for the simplest of
 * FE/BE interaction workflows such as SSL/GSS encryption requests.
 */
void
pqTraceOutputCharResponse(PGconn *conn, const char *responseType,
                          char response)
{
    if ((conn->traceFlags & PQTRACE_SUPPRESS_TIMESTAMPS) == 0)
    {
        char        timestr[128];
 
        pqTraceFormatTimestamp(timestr, sizeof(timestr));
        fprintf(conn->Pfdebug, "%s\t", timestr);
    }
 
    fprintf(conn->Pfdebug, "B\t1\t%s\t %c\n", responseType, response);
}