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Further fixes for quoted-list GUC values in pg_dump and ruleutils.c. 

Commits 742869946 et al turn out to be a couple bricks shy of a load.
We were dumping the stored values of GUC_LIST_QUOTE variables as they
appear in proconfig or setconfig catalog columns.  However, although that
quoting rule looks a lot like SQL-identifier double quotes, there are two
critical differences: empty strings ("") are legal, and depending on which
variable you're considering, values longer than NAMEDATALEN might be valid
too.  So the current technique fails altogether on empty-string list
entries (as reported by Steven Winfield in bug #15248) and it also risks
truncating file pathnames during dump/reload of GUC values that are lists
of pathnames.

To fix, split the stored value without any downcasing or truncation,
and then emit each element as a SQL string literal.

This is a tad annoying, because we now have three copies of the
comma-separated-string splitting logic in varlena.c as well as a fourth
one in dumputils.c.  (Not to mention the randomly-different-from-those
splitting logic in libpq...)  I looked at unifying these, but it would
be rather a mess unless we're willing to tweak the API definitions of
SplitIdentifierString, SplitDirectoriesString, or both.  That might be
worth doing in future; but it seems pretty unsafe for a back-patched
bug fix, so for now accept the duplication.

Back-patch to all supported branches, as the previous fix was.

Discussion: https://postgr.es/m/7585.1529435872@sss.pgh.pa.us
This commit is contained in:
Tom Lane 2018-07-31 13:00:08 -04:00
parent 5a71d3e583
commit a56c11d44d
8 changed files with 326 additions and 30 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

37
src/backend/utils/adt/ruleutils.c
View File

@ -2640,14 +2640,39 @@ pg_get_functiondef(PG_FUNCTION_ARGS)
/*
* Variables that are marked GUC_LIST_QUOTE were already fully
* quoted by flatten_set_variable_args() before they were put
* into the proconfig array; we mustn't re-quote them or we'll
* make a mess. Variables that are not so marked should just
* be emitted as simple string literals. If the variable is
* not known to guc.c, we'll do the latter; this makes it
* unsafe to use GUC_LIST_QUOTE for extension variables.
* into the proconfig array. However, because the quoting
* rules used there aren't exactly like SQL's, we have to
* break the list value apart and then quote the elements as
* string literals. (The elements may be double-quoted as-is,
* but we can't just feed them to the SQL parser; it would do
* the wrong thing with elements that are zero-length or
* longer than NAMEDATALEN.)
*
* Variables that are not so marked should just be emitted as
* simple string literals. If the variable is not known to
* guc.c, we'll do that; this makes it unsafe to use
* GUC_LIST_QUOTE for extension variables.
*/
if (GetConfigOptionFlags(configitem, true) & GUC_LIST_QUOTE)
appendStringInfoString(&buf, pos);
{
List *namelist;
ListCell *lc;
/* Parse string into list of identifiers */
if (!SplitGUCList(pos, ',', &namelist))
{
/* this shouldn't fail really */
elog(ERROR, "invalid list syntax in proconfig item");
}
foreach(lc, namelist)
{
char *curname = (char *) lfirst(lc);
simple_quote_literal(&buf, curname);
if (lnext(lc))
appendStringInfoString(&buf, ", ");
}
}
else
simple_quote_literal(&buf, pos);
appendStringInfoChar(&buf, '\n');

112
src/backend/utils/adt/varlena.c
View File

@ -3503,6 +3503,118 @@ SplitDirectoriesString(char *rawstring, char separator,
}
/*
* SplitGUCList --- parse a string containing identifiers or file names
*
* This is used to split the value of a GUC_LIST_QUOTE GUC variable, without
* presuming whether the elements will be taken as identifiers or file names.
* We assume the input has already been through flatten_set_variable_args(),
* so that we need never downcase (if appropriate, that was done already).
* Nor do we ever truncate, since we don't know the correct max length.
* We disallow embedded whitespace for simplicity (it shouldn't matter,
* because any embedded whitespace should have led to double-quoting).
* Otherwise the API is identical to SplitIdentifierString.
*
* XXX it's annoying to have so many copies of this string-splitting logic.
* However, it's not clear that having one function with a bunch of option
* flags would be much better.
*
* XXX there is a version of this function in src/bin/pg_dump/dumputils.c.
* Be sure to update that if you have to change this.
*
* Inputs:
* rawstring: the input string; must be overwritable! On return, it's
* been modified to contain the separated identifiers.
* separator: the separator punctuation expected between identifiers
* (typically '.' or ','). Whitespace may also appear around
* identifiers.
* Outputs:
* namelist: filled with a palloc'd list of pointers to identifiers within
* rawstring. Caller should list_free() this even on error return.
*
* Returns true if okay, false if there is a syntax error in the string.
*/
bool
SplitGUCList(char *rawstring, char separator,
List **namelist)
{
char *nextp = rawstring;
bool done = false;
*namelist = NIL;
while (scanner_isspace(*nextp))
nextp++; /* skip leading whitespace */
if (*nextp == '\0')
return true; /* allow empty string */
/* At the top of the loop, we are at start of a new identifier. */
do
{
char *curname;
char *endp;
if (*nextp == '"')
{
/* Quoted name --- collapse quote-quote pairs */
curname = nextp + 1;
for (;;)
{
endp = strchr(nextp + 1, '"');
if (endp == NULL)
return false; /* mismatched quotes */
if (endp[1] != '"')
break; /* found end of quoted name */
/* Collapse adjacent quotes into one quote, and look again */
memmove(endp, endp + 1, strlen(endp));
nextp = endp;
}
/* endp now points at the terminating quote */
nextp = endp + 1;
}
else
{
/* Unquoted name --- extends to separator or whitespace */
curname = nextp;
while (*nextp && *nextp != separator &&
!scanner_isspace(*nextp))
nextp++;
endp = nextp;
if (curname == nextp)
return false; /* empty unquoted name not allowed */
}
while (scanner_isspace(*nextp))
nextp++; /* skip trailing whitespace */
if (*nextp == separator)
{
nextp++;
while (scanner_isspace(*nextp))
nextp++; /* skip leading whitespace for next */
/* we expect another name, so done remains false */
}
else if (*nextp == '\0')
done = true;
else
return false; /* invalid syntax */
/* Now safe to overwrite separator with a null */
*endp = '\0';
/*
* Finished isolating current name --- add it to list
*/
*namelist = lappend(*namelist, curname);
/* Loop back if we didn't reach end of string */
} while (!done);
return true;
}
/*****************************************************************************
* Comparison Functions used for bytea
*

144
src/bin/pg_dump/dumputils.c
View File

@ -14,6 +14,8 @@
*/
#include "postgres_fe.h"
#include <ctype.h>
#include "dumputils.h"
#include "fe_utils/string_utils.h"
@ -873,6 +875,115 @@ variable_is_guc_list_quote(const char *name)
return false;
}
/*
* SplitGUCList --- parse a string containing identifiers or file names
*
* This is used to split the value of a GUC_LIST_QUOTE GUC variable, without
* presuming whether the elements will be taken as identifiers or file names.
* See comparable code in src/backend/utils/adt/varlena.c.
*
* Inputs:
* rawstring: the input string; must be overwritable! On return, it's
* been modified to contain the separated identifiers.
* separator: the separator punctuation expected between identifiers
* (typically '.' or ','). Whitespace may also appear around
* identifiers.
* Outputs:
* namelist: receives a malloc'd, null-terminated array of pointers to
* identifiers within rawstring. Caller should free this
* even on error return.
*
* Returns true if okay, false if there is a syntax error in the string.
*/
bool
SplitGUCList(char *rawstring, char separator,
char ***namelist)
{
char *nextp = rawstring;
bool done = false;
char **nextptr;
/*
* Since we disallow empty identifiers, this is a conservative
* overestimate of the number of pointers we could need. Allow one for
* list terminator.
*/
*namelist = nextptr = (char **)
pg_malloc((strlen(rawstring) / 2 + 2) * sizeof(char *));
*nextptr = NULL;
while (isspace((unsigned char) *nextp))
nextp++; /* skip leading whitespace */
if (*nextp == '\0')
return true; /* allow empty string */
/* At the top of the loop, we are at start of a new identifier. */
do
{
char *curname;
char *endp;
if (*nextp == '"')
{
/* Quoted name --- collapse quote-quote pairs */
curname = nextp + 1;
for (;;)
{
endp = strchr(nextp + 1, '"');
if (endp == NULL)
return false; /* mismatched quotes */
if (endp[1] != '"')
break; /* found end of quoted name */
/* Collapse adjacent quotes into one quote, and look again */
memmove(endp, endp + 1, strlen(endp));
nextp = endp;
}
/* endp now points at the terminating quote */
nextp = endp + 1;
}
else
{
/* Unquoted name --- extends to separator or whitespace */
curname = nextp;
while (*nextp && *nextp != separator &&
!isspace((unsigned char) *nextp))
nextp++;
endp = nextp;
if (curname == nextp)
return false; /* empty unquoted name not allowed */
}
while (isspace((unsigned char) *nextp))
nextp++; /* skip trailing whitespace */
if (*nextp == separator)
{
nextp++;
while (isspace((unsigned char) *nextp))
nextp++; /* skip leading whitespace for next */
/* we expect another name, so done remains false */
}
else if (*nextp == '\0')
done = true;
else
return false; /* invalid syntax */
/* Now safe to overwrite separator with a null */
*endp = '\0';
/*
* Finished isolating current name --- add it to output array
*/
*nextptr++ = curname;
/* Loop back if we didn't reach end of string */
} while (!done);
*nextptr = NULL;
return true;
}
/*
* Helper function for dumping "ALTER DATABASE/ROLE SET ..." commands.
*
@ -912,14 +1023,35 @@ makeAlterConfigCommand(PGconn *conn, const char *configitem,
/*
* Variables that are marked GUC_LIST_QUOTE were already fully quoted by
* flatten_set_variable_args() before they were put into the setconfig
* array; we mustn't re-quote them or we'll make a mess. Variables that
* are not so marked should just be emitted as simple string literals. If
* the variable is not known to variable_is_guc_list_quote(), we'll do the
* latter; this makes it unsafe to use GUC_LIST_QUOTE for extension
* variables.
* array. However, because the quoting rules used there aren't exactly
* like SQL's, we have to break the list value apart and then quote the
* elements as string literals. (The elements may be double-quoted as-is,
* but we can't just feed them to the SQL parser; it would do the wrong
* thing with elements that are zero-length or longer than NAMEDATALEN.)
*
* Variables that are not so marked should just be emitted as simple
* string literals. If the variable is not known to
* variable_is_guc_list_quote(), we'll do that; this makes it unsafe to
* use GUC_LIST_QUOTE for extension variables.
*/
if (variable_is_guc_list_quote(mine))
appendPQExpBufferStr(buf, pos);
{
char **namelist;
char **nameptr;
/* Parse string into list of identifiers */
/* this shouldn't fail really */
if (SplitGUCList(pos, ',', &namelist))
{
for (nameptr = namelist; *nameptr; nameptr++)
{
if (nameptr != namelist)
appendPQExpBufferStr(buf, ", ");
appendStringLiteralConn(buf, *nameptr, conn);
}
}
pg_free(namelist);
}
else
appendStringLiteralConn(buf, pos, conn);

3
src/bin/pg_dump/dumputils.h
View File

@ -58,6 +58,9 @@ extern void buildACLQueries(PQExpBuffer acl_subquery, PQExpBuffer racl_subquery,
extern bool variable_is_guc_list_quote(const char *name);
extern bool SplitGUCList(char *rawstring, char separator,
char ***namelist);
extern void makeAlterConfigCommand(PGconn *conn, const char *configitem,
const char *type, const char *name,
const char *type2, const char *name2,

30
src/bin/pg_dump/pg_dump.c
View File

@ -11955,14 +11955,36 @@ dumpFunc(Archive *fout, FuncInfo *finfo)
/*
* Variables that are marked GUC_LIST_QUOTE were already fully quoted
* by flatten_set_variable_args() before they were put into the
* proconfig array; we mustn't re-quote them or we'll make a mess.
* proconfig array. However, because the quoting rules used there
* aren't exactly like SQL's, we have to break the list value apart
* and then quote the elements as string literals. (The elements may
* be double-quoted as-is, but we can't just feed them to the SQL
* parser; it would do the wrong thing with elements that are
* zero-length or longer than NAMEDATALEN.)
*
* Variables that are not so marked should just be emitted as simple
* string literals. If the variable is not known to
* variable_is_guc_list_quote(), we'll do the latter; this makes it
* unsafe to use GUC_LIST_QUOTE for extension variables.
* variable_is_guc_list_quote(), we'll do that; this makes it unsafe
* to use GUC_LIST_QUOTE for extension variables.
*/
if (variable_is_guc_list_quote(configitem))
appendPQExpBufferStr(q, pos);
{
char **namelist;
char **nameptr;
/* Parse string into list of identifiers */
/* this shouldn't fail really */
if (SplitGUCList(pos, ',', &namelist))
{
for (nameptr = namelist; *nameptr; nameptr++)
{
if (nameptr != namelist)
appendPQExpBufferStr(q, ", ");
appendStringLiteralAH(q, *nameptr, fout);
}
}
pg_free(namelist);
}
else
appendStringLiteralAH(q, pos, fout);
}

2
src/include/utils/varlena.h
View File

@ -31,6 +31,8 @@ extern bool SplitIdentifierString(char *rawstring, char separator,
List **namelist);
extern bool SplitDirectoriesString(char *rawstring, char separator,
List **namelist);
extern bool SplitGUCList(char *rawstring, char separator,
List **namelist);
extern text *replace_text_regexp(text *src_text, void *regexp,
text *replace_text, bool glob);

26
src/test/regress/expected/rules.out
View File

@ -3160,21 +3160,21 @@ CREATE FUNCTION func_with_set_params() RETURNS integer
SET extra_float_digits TO 2
SET work_mem TO '4MB'
SET datestyle to iso, mdy
SET local_preload_libraries TO "Mixed/Case", 'c:/"a"/path'
SET local_preload_libraries TO "Mixed/Case", 'c:/''a"/path', '', '0123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789'
IMMUTABLE STRICT;
SELECT pg_get_functiondef('func_with_set_params()'::regprocedure);
pg_get_functiondef
---------------------------------------------------------------
CREATE OR REPLACE FUNCTION public.func_with_set_params() +
RETURNS integer +
LANGUAGE sql +
IMMUTABLE STRICT +
SET search_path TO pg_catalog +
SET extra_float_digits TO '2' +
SET work_mem TO '4MB' +
SET "DateStyle" TO 'iso, mdy' +
SET local_preload_libraries TO "Mixed/Case", "c:/""a""/path"+
AS $function$select 1;$function$ +
pg_get_functiondef
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------
CREATE OR REPLACE FUNCTION public.func_with_set_params() +
RETURNS integer +
LANGUAGE sql +
IMMUTABLE STRICT +
SET search_path TO 'pg_catalog' +
SET extra_float_digits TO '2' +
SET work_mem TO '4MB' +
SET "DateStyle" TO 'iso, mdy' +
SET local_preload_libraries TO 'Mixed/Case', 'c:/''a"/path', '', '0123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789'+
AS $function$select 1;$function$ +
(1 row)

2
src/test/regress/sql/rules.sql
View File

@ -1164,7 +1164,7 @@ CREATE FUNCTION func_with_set_params() RETURNS integer
SET extra_float_digits TO 2
SET work_mem TO '4MB'
SET datestyle to iso, mdy
SET local_preload_libraries TO "Mixed/Case", 'c:/"a"/path'
SET local_preload_libraries TO "Mixed/Case", 'c:/''a"/path', '', '0123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789'
IMMUTABLE STRICT;
SELECT pg_get_functiondef('func_with_set_params()'::regprocedure);