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Modify readfuncs so that recursive use of stringToNode will not crash

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and burn.  Just for added luck, change reading of CONST nodes so that
we do not need to consult pg_type rows while reading them; this means
that no database access occurs during stringToNode.  This requires
changing the order in which const-node fields are written, which means
an initdb is forced.
This commit is contained in:
Tom Lane
2001-01-07 01:08:48 +00:00
parent 1402201463
commit 4057b64f32
5 changed files with 438 additions and 459 deletions
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58
src/backend/nodes/read.c
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@ -9,7 +9,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/nodes/read.c,v 1.26 2000/12/03 20:45:33 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/nodes/read.c,v 1.27 2001/01/07 01:08:47 tgl Exp $
*
* HISTORY
* AUTHOR DATE MAJOR EVENT
@ -25,6 +25,11 @@
#include "nodes/pg_list.h"
#include "nodes/readfuncs.h"
/* Static state for pg_strtok */
static char *pg_strtok_ptr = NULL;
/*
* stringToNode -
* returns a Node with a given legal ASCII representation
@ -32,10 +37,22 @@
void *
stringToNode(char *str)
{
char *save_strtok;
void *retval;
lsptok(str, NULL); /* set the string used in lsptok */
retval = nodeRead(true); /* start reading */
/*
* We save and restore the pre-existing state of pg_strtok.
* This makes the world safe for re-entrant invocation of stringToNode,
* without incurring a lot of notational overhead by having to pass the
* next-character pointer around through all the readfuncs.c code.
*/
save_strtok = pg_strtok_ptr;
pg_strtok_ptr = str; /* point pg_strtok at the string to read */
retval = nodeRead(true); /* do the reading */
pg_strtok_ptr = save_strtok;
return retval;
}
@ -47,7 +64,7 @@ stringToNode(char *str)
*****************************************************************************/
/*
* lsptok --- retrieve next "token" from a string.
* pg_strtok --- retrieve next "token" from a string.
*
* Works kinda like strtok, except it never modifies the source string.
* (Instead of storing nulls into the string, the length of the token
@ -55,9 +72,7 @@ stringToNode(char *str)
* Also, the rules about what is a token are hard-wired rather than being
* configured by passing a set of terminating characters.
*
* The string is initially set by passing a non-NULL "string" value,
* and subsequent calls with string==NULL read the previously given value.
* (Pass length==NULL to set the string without reading its first token.)
* The string is assumed to have been initialized already by stringToNode.
*
* The rules for tokens are:
* * Whitespace (space, tab, newline) always separates tokens.
@ -89,20 +104,12 @@ stringToNode(char *str)
* as a single token.
*/
char *
lsptok(char *string, int *length)
pg_strtok(int *length)
{
static char *saved_str = NULL;
char *local_str; /* working pointer to string */
char *ret_str; /* start of token to return */
if (string != NULL)
{
saved_str = string;
if (length == NULL)
return NULL;
}
local_str = saved_str;
local_str = pg_strtok_ptr;
while (*local_str == ' ' || *local_str == '\n' || *local_str == '\t')
local_str++;
@ -110,7 +117,7 @@ lsptok(char *string, int *length)
if (*local_str == '\0')
{
*length = 0;
saved_str = local_str;
pg_strtok_ptr = local_str;
return NULL; /* no more tokens */
}
@ -147,7 +154,7 @@ lsptok(char *string, int *length)
if (*length == 2 && ret_str[0] == '<' && ret_str[1] == '>')
*length = 0;
saved_str = local_str;
pg_strtok_ptr = local_str;
return ret_str;
}
@ -223,7 +230,7 @@ nodeTokenType(char *token, int length)
}
/*
* these three cases do not need length checks, since lsptok() will
* these three cases do not need length checks, since pg_strtok() will
* always treat them as single-byte tokens
*/
else if (*token == '(')
@ -248,12 +255,13 @@ nodeTokenType(char *token, int length)
* Slightly higher-level reader.
*
* This routine applies some semantic knowledge on top of the purely
* lexical tokenizer lsptok(). It can read
* lexical tokenizer pg_strtok(). It can read
* * Value token nodes (integers, floats, or strings);
* * Plan nodes (via parsePlanString() from readfuncs.c);
* * Lists of the above.
*
* Secrets: He assumes that lsptok already has the string (see above).
* We assume pg_strtok is already initialized with a string to read (hence
* this should only be invoked from within a stringToNode operation).
* Any callers should set read_car_only to true.
*/
void *
@ -266,7 +274,7 @@ nodeRead(bool read_car_only)
*return_value;
bool make_dotted_pair_cell = false;
token = lsptok(NULL, &tok_len);
token = pg_strtok(&tok_len);
if (token == NULL)
return NULL;
@ -277,8 +285,8 @@ nodeRead(bool read_car_only)
{
case PLAN_SYM:
this_value = parsePlanString();
token = lsptok(NULL, &tok_len);
if (token[0] != '}')
token = pg_strtok(&tok_len);
if (token == NULL || token[0] != '}')
elog(ERROR, "nodeRead: did not find '}' at end of plan node");
if (!read_car_only)
make_dotted_pair_cell = true;