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/*
* stringinfo.c
* These are routines that can be used to write informations to a string,
* without having to worry about string lengths, space allocation etc.
* Ideally the interface should look like the file i/o interface,
*
* Copyright (c) 1994, Regents of the University of California
*
* $Id: stringinfo.c,v 1.14 1999/02/13 23:15:36 momjian Exp $
*/
#include <stdio.h>
#include <string.h>
#include <stdarg.h>
#include <postgres.h>
#include <nodes/pg_list.h>
#include <lib/stringinfo.h>
/*
* makeStringInfo
*
* Create a StringInfoData & return a pointer to it.
*
*/
StringInfo
makeStringInfo()
{
StringInfo res;
int size;
res = (StringInfo) palloc(sizeof(StringInfoData));
if (res == NULL)
elog(ERROR, "makeStringInfo: Out of memory!");
size = 256; /* initial default size */
res->data = palloc(size);
if (res->data == NULL)
{
elog(ERROR,
"makeStringInfo: Out of memory! (%d bytes requested)", size);
}
res->maxlen = size;
res->len = 0;
/* Make sure the string is empty initially. */
res->data[0] = '\0';
return res;
}
/*
* appendStringInfo
*
* append to the current 'StringInfo' a new string.
* If there is not enough space in the current 'data', then reallocate
* some more...
*
* NOTE: if we reallocate space, we pfree the old one!
*
*/
void
appendStringInfo(StringInfo str, const char *fmt,...)
{
int buflen,
newlen,
needed;
char *s,
buffer[512];
va_list args;
va_start(args, fmt);
buflen = vsnprintf(buffer, 512, fmt, args);
va_end(args);
Assert(str != NULL);
if (buflen == 0)
strcpy(buffer, "<>");
/*
* do we have enough space to append the new string? (don't forget to
* count the null string terminating char!) If no, then reallocate
* some more.
*/
needed = str->len + buflen + 1;
if (needed > str->maxlen)
{
/*
* how much more space to allocate ? Let's say double the current
* space... However we must check if this is enough!
*/
newlen = 2 * str->maxlen;
while (needed > newlen)
newlen = 2 * newlen;
/*
* allocate enough space.
*/
s = palloc(newlen);
if (s == NULL)
{
elog(ERROR,
"appendStringInfo: Out of memory (%d bytes requested)", newlen);
}
/*
* transfer the data. strcpy() would work, but is probably a tad
* slower than memcpy(), and since we know the string length...
*/
memcpy(s, str->data, str->len + 1);
pfree(str->data);
str->maxlen = newlen;
str->data = s;
}
/*
* OK, we have enough space now, append 'buffer' at the end of the
* string & update the string length. NOTE: strcat() would work,
* but is certainly slower than just memcpy'ing the data to the right
* place.
*/
memcpy(str->data + str->len, buffer, buflen + 1);
str->len += buflen;
}
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