mirror/postgresql
2
0
Fork 0
mirror of https://git.postgresql.org/git/postgresql.git synced 2025-01-24 18:55:04 +08:00
Code Issues Packages Projects Releases Wiki Activity

Fix a potential infinite loop in appendStringInfo: would lock

Browse Source 
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
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

39
src/backend/lib/stringinfo.c
View File

@ -9,7 +9,7 @@
* *
* *
* IDENTIFICATION * 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() makeStringInfo()
{ {
StringInfo res; StringInfo res;
long size; int size;
res = (StringInfo) palloc(sizeof(StringInfoData)); res = (StringInfo) palloc(sizeof(StringInfoData));
if (res == NULL) if (res == NULL)
elog(ERROR, "makeStringInfo: Out of memory!"); elog(ERROR, "makeStringInfo: Out of memory!");
size = 100; size = 256; /* initial default size */
res->data = palloc(size); res->data = palloc(size);
if (res->data == NULL) if (res->data == NULL)
{ {
elog(ERROR, elog(ERROR,
"makeStringInfo: Out of memory! (%ld bytes requested)", size); "makeStringInfo: Out of memory! (%d bytes requested)", size);
} }
res->maxlen = size; res->maxlen = size;
res->len = 0; res->len = 0;
/* Make sure the string is empty initially. */
/*
* 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.
*/
res->data[0] = '\0'; res->data[0] = '\0';
return res; return res;
@ -71,7 +66,8 @@ void
appendStringInfo(StringInfo str, char *buffer) appendStringInfo(StringInfo str, char *buffer)
{ {
int buflen, int buflen,
newlen; newlen,
needed;
char *s; char *s;
Assert(str != NULL); Assert(str != NULL);
@ -84,15 +80,16 @@ appendStringInfo(StringInfo str, char *buffer)
* some more. * some more.
*/ */
buflen = strlen(buffer); 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 * how much more space to allocate ? Let's say double the current
* space... However we must check if this is enough! * space... However we must check if this is enough!
*/ */
newlen = 2 * str->len; newlen = 2 * str->maxlen;
while (buflen + str->len >= newlen - 1) while (needed > newlen)
newlen = 2 * newlen; newlen = 2 * newlen;
/* /*
@ -105,7 +102,11 @@ appendStringInfo(StringInfo str, char *buffer)
"appendStringInfo: Out of memory (%d bytes requested)", "appendStringInfo: Out of memory (%d bytes requested)",
newlen); 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); pfree(str->data);
str->maxlen = newlen; str->maxlen = newlen;
str->data = s; 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 * OK, we have enough space now, append 'buffer' at the end of the
* string & update the string length. NOTE: this is a text string * string & update the string length. NOTE: strcat() would work,
* (i.e. printable characters) so 'strcat' will do the job (no need to * but is certainly slower than just memcpy'ing the data to the right
* use 'bcopy' et all...) * place.
*/ */
strcat(str->data, buffer); memcpy(str->data + str->len, buffer, buflen + 1);
str->len += buflen; str->len += buflen;
} }