From a56c11d44dfcce1cbed3a6ed243ae43e001dfb9f Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Tue, 31 Jul 2018 13:00:08 -0400 Subject: 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 --- src/backend/utils/adt/ruleutils.c | 37 +++++++++++++++++++++++++++++++------ 1 file changed, 31 insertions(+), 6 deletions(-) (limited to 'src/backend/utils/adt/ruleutils.c') diff --git a/src/backend/utils/adt/ruleutils.c b/src/backend/utils/adt/ruleutils.c index 5a61d2dac00..03e9a28a63b 100644 --- a/src/backend/utils/adt/ruleutils.c +++ b/src/backend/utils/adt/ruleutils.c @@ -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'); -- cgit v1.2.3