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/*-------------------------------------------------------------------------
*
* stringinfo.c
*
* StringInfo 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 palloc().
*
* Copyright (c) 1994, Regents of the University of California
*
* $Id: stringinfo.c,v 1.23 1999/11/01 05:10:32 tgl Exp $
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include "lib/stringinfo.h"
/*
* makeStringInfo
*
* Create an empty 'StringInfoData' & return a pointer to it.
*/
StringInfo
makeStringInfo(void)
{
StringInfo res;
res = (StringInfo) palloc(sizeof(StringInfoData));
if (res == NULL)
elog(ERROR, "makeStringInfo: Out of memory");
initStringInfo(res);
return res;
}
/*
* initStringInfo
*
* Initialize a StringInfoData struct (with previously undefined contents)
* to describe an empty string.
*/
void
initStringInfo(StringInfo str)
{
int size = 256; /* initial default buffer size */
str->data = (char *) palloc(size);
if (str->data == NULL)
elog(ERROR,
"initStringInfo: Out of memory (%d bytes requested)", size);
str->maxlen = size;
str->len = 0;
str->data[0] = '\0';
}
/*
* enlargeStringInfo
*
* Internal routine: make sure there is enough space for 'needed' more bytes
* ('needed' does not include the terminating null).
*/
static void
enlargeStringInfo(StringInfo str, int needed)
{
int newlen;
needed += str->len + 1; /* total space required now */
if (needed <= str->maxlen)
return; /* 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 = 2 * str->maxlen;
while (needed > newlen)
newlen = 2 * newlen;
str->data = (char *) repalloc(str->data, newlen);
if (str->data == NULL)
elog(ERROR,
"enlargeStringInfo: Out of memory (%d bytes requested)", newlen);
str->maxlen = newlen;
}
/*
* appendStringInfo
*
* 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
appendStringInfo(StringInfo str, const char *fmt,...)
{
va_list args;
int avail,
nprinted;
Assert(str != NULL);
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. */
enlargeStringInfo(str, str->maxlen);
}
}
/*------------------------
* appendStringInfoChar
* Append a single byte to str.
* Like appendStringInfo(str, "%c", ch) but much faster.
*/
void
appendStringInfoChar(StringInfo str, char ch)
{
/* Make more room if needed */
if (str->len + 1 >= str->maxlen)
enlargeStringInfo(str, 1);
/* OK, append the character */
str->data[str->len] = ch;
str->len++;
str->data[str->len] = '\0';
}
/*
* appendBinaryStringInfo
*
* Append arbitrary binary data to a StringInfo, allocating more space
* if necessary.
*/
void
appendBinaryStringInfo(StringInfo str, const char *data, int datalen)
{
Assert(str != NULL);
/* Make more room if needed */
enlargeStringInfo(str, datalen);
/* 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';
}
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