/*------------------------------------------------------------------------- * * pqexpbuffer.c * * PQExpBuffer provides an indefinitely-extensible string data type. * It can be used to buffer either ordinary C strings (null-terminated text) * or arbitrary binary data. All storage is allocated with malloc(). * * This module is essentially the same as the backend's StringInfo data type, * but it is intended for use in frontend libpq and client applications. * Thus, it does not rely on palloc() nor elog(). * * It does rely on vsnprintf(); if configure finds that libc doesn't provide * a usable vsnprintf(), then a copy of our own implementation of it will * be linked into libpq. * * Portions Copyright (c) 1996-2000, PostgreSQL, Inc * Portions Copyright (c) 1994, Regents of the University of California * * $Header: /cvsroot/pgsql/src/interfaces/libpq/pqexpbuffer.c,v 1.6 2000/04/12 17:17:15 momjian Exp $ * *------------------------------------------------------------------------- */ #include "postgres.h" #include "pqexpbuffer.h" #ifdef WIN32 #include #include #include "win32.h" #endif /* * createPQExpBuffer * * Create an empty 'PQExpBufferData' & return a pointer to it. */ PQExpBuffer createPQExpBuffer(void) { PQExpBuffer res; res = (PQExpBuffer) malloc(sizeof(PQExpBufferData)); if (res != NULL) initPQExpBuffer(res); return res; } /* * initPQExpBuffer * * Initialize a PQExpBufferData struct (with previously undefined contents) * to describe an empty string. */ void initPQExpBuffer(PQExpBuffer str) { str->data = (char *) malloc(INITIAL_EXPBUFFER_SIZE); if (str->data == NULL) { str->maxlen = 0; str->len = 0; } else { str->maxlen = INITIAL_EXPBUFFER_SIZE; str->len = 0; str->data[0] = '\0'; } } /*------------------------ * destroyPQExpBuffer(str); * free()s both the data buffer and the PQExpBufferData. * This is the inverse of createPQExpBuffer(). */ void destroyPQExpBuffer(PQExpBuffer str) { if (str) { termPQExpBuffer(str); free(str); } } /*------------------------ * termPQExpBuffer(str) * free()s the data buffer but not the PQExpBufferData itself. * This is the inverse of initPQExpBuffer(). */ void termPQExpBuffer(PQExpBuffer str) { if (str->data) { free(str->data); str->data = NULL; } } /*------------------------ * resetPQExpBuffer * Reset a PQExpBuffer to empty */ void resetPQExpBuffer(PQExpBuffer str) { if (str) { str->len = 0; if (str->data) str->data[0] = '\0'; } } /*------------------------ * enlargePQExpBuffer * Make sure there is enough space for 'needed' more bytes in the buffer * ('needed' does not include the terminating null). * * Returns 1 if OK, 0 if failed to enlarge buffer. */ int enlargePQExpBuffer(PQExpBuffer str, size_t needed) { size_t newlen; char *newdata; needed += str->len + 1; /* total space required now */ if (needed <= str->maxlen) return 1; /* got enough space already */ /* * We don't want to allocate just a little more space with each * append; for efficiency, double the buffer size each time it * overflows. Actually, we might need to more than double it if * 'needed' is big... */ newlen = str->maxlen ? (2 * str->maxlen) : 64; while (needed > newlen) newlen = 2 * newlen; newdata = (char *) realloc(str->data, newlen); if (newdata != NULL) { str->data = newdata; str->maxlen = newlen; return 1; } return 0; } /*------------------------ * printfPQExpBuffer * Format text data under the control of fmt (an sprintf-like format string) * and insert it into str. More space is allocated to str if necessary. * This is a convenience routine that does the same thing as * resetPQExpBuffer() followed by appendPQExpBuffer(). */ void printfPQExpBuffer(PQExpBuffer str, const char *fmt,...) { va_list args; size_t avail; int nprinted; resetPQExpBuffer(str); for (;;) { /*---------- * Try to format the given string into the available space; * but if there's hardly any space, don't bother trying, * just fall through to enlarge the buffer first. *---------- */ avail = str->maxlen - str->len - 1; if (avail > 16) { va_start(args, fmt); nprinted = vsnprintf(str->data + str->len, avail, fmt, args); va_end(args); /* * Note: some versions of vsnprintf return the number of chars * actually stored, but at least one returns -1 on failure. Be * conservative about believing whether the print worked. */ if (nprinted >= 0 && nprinted < avail - 1) { /* Success. Note nprinted does not include trailing null. */ str->len += nprinted; break; } } /* Double the buffer size and try again. */ if (!enlargePQExpBuffer(str, str->maxlen)) return; /* oops, out of memory */ } } /*------------------------ * appendPQExpBuffer * * Format text data under the control of fmt (an sprintf-like format string) * and append it to whatever is already in str. More space is allocated * to str if necessary. This is sort of like a combination of sprintf and * strcat. */ void appendPQExpBuffer(PQExpBuffer str, const char *fmt,...) { va_list args; size_t avail; int nprinted; for (;;) { /*---------- * Try to format the given string into the available space; * but if there's hardly any space, don't bother trying, * just fall through to enlarge the buffer first. *---------- */ avail = str->maxlen - str->len - 1; if (avail > 16) { va_start(args, fmt); nprinted = vsnprintf(str->data + str->len, avail, fmt, args); va_end(args); /* * Note: some versions of vsnprintf return the number of chars * actually stored, but at least one returns -1 on failure. Be * conservative about believing whether the print worked. */ if (nprinted >= 0 && nprinted < avail - 1) { /* Success. Note nprinted does not include trailing null. */ str->len += nprinted; break; } } /* Double the buffer size and try again. */ if (!enlargePQExpBuffer(str, str->maxlen)) return; /* oops, out of memory */ } } /*------------------------ * appendPQExpBufferStr * Append the given string to a PQExpBuffer, allocating more space * if necessary. */ void appendPQExpBufferStr(PQExpBuffer str, const char *data) { appendBinaryPQExpBuffer(str, data, strlen(data)); } /*------------------------ * appendPQExpBufferChar * Append a single byte to str. * Like appendPQExpBuffer(str, "%c", ch) but much faster. */ void appendPQExpBufferChar(PQExpBuffer str, char ch) { /* Make more room if needed */ if (!enlargePQExpBuffer(str, 1)) return; /* OK, append the character */ str->data[str->len] = ch; str->len++; str->data[str->len] = '\0'; } /* * appendBinaryPQExpBuffer * * Append arbitrary binary data to a PQExpBuffer, allocating more space * if necessary. */ void appendBinaryPQExpBuffer(PQExpBuffer str, const char *data, size_t datalen) { /* Make more room if needed */ if (!enlargePQExpBuffer(str, datalen)) return; /* OK, append the data */ memcpy(str->data + str->len, data, datalen); str->len += datalen; /* * Keep a trailing null in place, even though it's probably useless * for binary data... */ str->data[str->len] = '\0'; }