Fix multibyte issue in ltree_strncasecmp().

Previously, the API for ltree_strncasecmp() took two inputs but only
one length (that of the smaller input). It truncated the larger input
to that length, but that could break a multibyte sequence.

Change the API to be a check for prefix equality (possibly
case-insensitive) instead, which is all that's needed by the
callers. Also, provide the lengths of both inputs.

Reviewed-by: Chao Li <[email protected]>
Reviewed-by: Peter Eisentraut <[email protected]>
Discussion: https://postgr.es/m/5f65b85740197ba6249ea507cddf609f84a6188b.camel%40j-davis.com
Backpatch-through: 14

diff --git a/contrib/ltree/lquery_op.c b/contrib/ltree/lquery_op.c
index ef86046fc4bc0f1d0d98753817598b9b7ba73ce3..d89af20f6cfb00ddb98dddc9e01a5dde929f50de 100644 (file)
--- a/contrib/ltree/lquery_op.c
+++ b/contrib/ltree/lquery_op.c
@@ -41,7 +41,8 @@ getlexeme(char *start, char *end, int *len)
 }
 
 bool
-compare_subnode(ltree_level *t, char *qn, int len, int (*cmpptr) (const char *, const char *, size_t), bool anyend)
+compare_subnode(ltree_level *t, char *qn, int len,
+               ltree_prefix_eq_func prefix_eq, bool anyend)
 {
    char       *endt = t->name + t->len;
    char       *endq = qn + len;
@@ -57,7 +58,7 @@ compare_subnode(ltree_level *t, char *qn, int len, int (*cmpptr) (const char *,
        while ((tn = getlexeme(tn, endt, &lent)) != NULL)
        {
            if ((lent == lenq || (lent > lenq && anyend)) &&
-               (*cmpptr) (qn, tn, lenq) == 0)
+               (*prefix_eq) (qn, lenq, tn, lent))
            {
 
                isok = true;
@@ -74,14 +75,29 @@ compare_subnode(ltree_level *t, char *qn, int len, int (*cmpptr) (const char *,
    return true;
 }
 
-int
-ltree_strncasecmp(const char *a, const char *b, size_t s)
+/*
+ * Check if 'a' is a prefix of 'b'.
+ */
+bool
+ltree_prefix_eq(const char *a, size_t a_sz, const char *b, size_t b_sz)
+{
+   if (a_sz > b_sz)
+       return false;
+   else
+       return (strncmp(a, b, a_sz) == 0);
+}
+
+/*
+ * Case-insensitive check if 'a' is a prefix of 'b'.
+ */
+bool
+ltree_prefix_eq_ci(const char *a, size_t a_sz, const char *b, size_t b_sz)
 {
-   char       *al = str_tolower(a, s, DEFAULT_COLLATION_OID);
-   char       *bl = str_tolower(b, s, DEFAULT_COLLATION_OID);
-   int         res;
+   char       *al = str_tolower(a, a_sz, DEFAULT_COLLATION_OID);
+   char       *bl = str_tolower(b, b_sz, DEFAULT_COLLATION_OID);
+   bool        res;
 
-   res = strncmp(al, bl, s);
+   res = (strncmp(al, bl, a_sz) == 0);
 
    pfree(al);
    pfree(bl);
@@ -109,19 +125,19 @@ checkLevel(lquery_level *curq, ltree_level *curt)
 
    for (int i = 0; i < curq->numvar; i++)
    {
-       int         (*cmpptr) (const char *, const char *, size_t);
+       ltree_prefix_eq_func prefix_eq;
 
-       cmpptr = (curvar->flag & LVAR_INCASE) ? ltree_strncasecmp : strncmp;
+       prefix_eq = (curvar->flag & LVAR_INCASE) ? ltree_prefix_eq_ci : ltree_prefix_eq;
 
        if (curvar->flag & LVAR_SUBLEXEME)
        {
-           if (compare_subnode(curt, curvar->name, curvar->len, cmpptr,
+           if (compare_subnode(curt, curvar->name, curvar->len, prefix_eq,
                                (curvar->flag & LVAR_ANYEND)))
                return success;
        }
        else if ((curvar->len == curt->len ||
                  (curt->len > curvar->len && (curvar->flag & LVAR_ANYEND))) &&
-                (*cmpptr) (curvar->name, curt->name, curvar->len) == 0)
+                (*prefix_eq) (curvar->name, curvar->len, curt->name, curt->len))
            return success;
 
        curvar = LVAR_NEXT(curvar);

diff --git a/contrib/ltree/ltree.h b/contrib/ltree/ltree.h
index 83fc705ef8600da8bc9332d77811785afc3c29db..4e18caeb2fc283fe9d9979a5b137772f8584cc67 100644 (file)
--- a/contrib/ltree/ltree.h
+++ b/contrib/ltree/ltree.h
@@ -143,6 +143,8 @@ typedef struct
    char        data[FLEXIBLE_ARRAY_MEMBER];
 } ltxtquery;
 
+typedef bool (*ltree_prefix_eq_func) (const char *, size_t, const char *, size_t);
+
 #define HDRSIZEQT      MAXALIGN(VARHDRSZ + sizeof(int32))
 #define COMPUTESIZE(size,lenofoperand) ( HDRSIZEQT + (size) * sizeof(ITEM) + (lenofoperand) )
 #define LTXTQUERY_TOO_BIG(size,lenofoperand) \
@@ -193,10 +195,11 @@ bool      ltree_execute(ITEM *curitem, void *checkval,
 
 int            ltree_compare(const ltree *a, const ltree *b);
 bool       inner_isparent(const ltree *c, const ltree *p);
-bool       compare_subnode(ltree_level *t, char *q, int len,
-                           int (*cmpptr) (const char *, const char *, size_t), bool anyend);
+bool       compare_subnode(ltree_level *t, char *qn, int len,
+                           ltree_prefix_eq_func prefix_eq, bool anyend);
 ltree     *lca_inner(ltree **a, int len);
-int            ltree_strncasecmp(const char *a, const char *b, size_t s);
+bool       ltree_prefix_eq(const char *a, size_t a_sz, const char *b, size_t b_sz);
+bool       ltree_prefix_eq_ci(const char *a, size_t a_sz, const char *b, size_t b_sz);
 
 /* fmgr macros for ltree objects */
 #define DatumGetLtreeP(X)          ((ltree *) PG_DETOAST_DATUM(X))

diff --git a/contrib/ltree/ltxtquery_op.c b/contrib/ltree/ltxtquery_op.c
index 002102c9c75b69466d79852448ad488a2905890a..3dcbab2c4846017bf3fa30ed8c28d73f40ef38ad 100644 (file)
--- a/contrib/ltree/ltxtquery_op.c
+++ b/contrib/ltree/ltxtquery_op.c
@@ -58,19 +58,19 @@ checkcondition_str(void *checkval, ITEM *val)
    ltree_level *level = LTREE_FIRST(((CHKVAL *) checkval)->node);
    int         tlen = ((CHKVAL *) checkval)->node->numlevel;
    char       *op = ((CHKVAL *) checkval)->operand + val->distance;
-   int         (*cmpptr) (const char *, const char *, size_t);
+   ltree_prefix_eq_func prefix_eq;
 
-   cmpptr = (val->flag & LVAR_INCASE) ? ltree_strncasecmp : strncmp;
+   prefix_eq = (val->flag & LVAR_INCASE) ? ltree_prefix_eq_ci : ltree_prefix_eq;
    while (tlen > 0)
    {
        if (val->flag & LVAR_SUBLEXEME)
        {
-           if (compare_subnode(level, op, val->length, cmpptr, (val->flag & LVAR_ANYEND)))
+           if (compare_subnode(level, op, val->length, prefix_eq, (val->flag & LVAR_ANYEND)))
                return true;
        }
        else if ((val->length == level->len ||
                  (level->len > val->length && (val->flag & LVAR_ANYEND))) &&
-                (*cmpptr) (op, level->name, val->length) == 0)
+                (*prefix_eq) (op, val->length, level->name, level->len))
            return true;
 
        tlen--;