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Fix a potential infinite loop in appendStringInfo: would lock

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up if first string to be appended to an empty StringInfo was longer
than the initial space allocation.
Also speed it up slightly.
This commit is contained in:
Tom Lane 1998-11-08 19:22:24 +00:00
parent 4f920a66f4
commit 8f5ff4cf1c
1 changed files with 20 additions and 19 deletions
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39
src/backend/lib/stringinfo.c
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@ -9,7 +9,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/lib/stringinfo.c,v 1.11 1998/09/01 03:22:39 momjian Exp $
* $Header: /cvsroot/pgsql/src/backend/lib/stringinfo.c,v 1.12 1998/11/08 19:22:24 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -31,27 +31,22 @@ StringInfo
makeStringInfo()
{
StringInfo res;
long size;
int size;
res = (StringInfo) palloc(sizeof(StringInfoData));
if (res == NULL)
elog(ERROR, "makeStringInfo: Out of memory!");
size = 100;
size = 256; /* initial default size */
res->data = palloc(size);
if (res->data == NULL)
{
elog(ERROR,
"makeStringInfo: Out of memory! (%ld bytes requested)", size);
"makeStringInfo: Out of memory! (%d bytes requested)", size);
}
res->maxlen = size;
res->len = 0;
/*
* NOTE: we must initialize `res->data' to the empty string because we
* use 'strcat' in 'appendStringInfo', which of course it always
* expects a null terminated string.
*/
/* Make sure the string is empty initially. */
res->data[0] = '\0';
return res;
@ -71,7 +66,8 @@ void
appendStringInfo(StringInfo str, char *buffer)
{
int buflen,
newlen;
newlen,
needed;
char *s;
Assert(str != NULL);
@ -84,15 +80,16 @@ appendStringInfo(StringInfo str, char *buffer)
* some more.
*/
buflen = strlen(buffer);
if (buflen + str->len >= str->maxlen - 1)
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->len;
while (buflen + str->len >= newlen - 1)
newlen = 2 * str->maxlen;
while (needed > newlen)
newlen = 2 * newlen;
/*
@ -105,7 +102,11 @@ appendStringInfo(StringInfo str, char *buffer)
"appendStringInfo: Out of memory (%d bytes requested)",
newlen);
}
memmove(s, str->data, str->len + 1);
/*
* 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;
@ -113,10 +114,10 @@ appendStringInfo(StringInfo str, char *buffer)
/*
* OK, we have enough space now, append 'buffer' at the end of the
* string & update the string length. NOTE: this is a text string
* (i.e. printable characters) so 'strcat' will do the job (no need to
* use 'bcopy' et all...)
* string & update the string length. NOTE: strcat() would work,
* but is certainly slower than just memcpy'ing the data to the right
* place.
*/
strcat(str->data, buffer);
memcpy(str->data + str->len, buffer, buflen + 1);
str->len += buflen;
}