From 1696178edf8121ab680baa121fa2b851d1a78cd8 Mon Sep 17 00:00:00 2001
From: Michal Vasko <mvasko@cesnet.cz>
Date: Wed, 1 Nov 2023 10:55:36 +0100
Subject: [PATCH] xpath UPDATE do not use memstream

Not supported on Windows.
---
 src/xpath.c | 64 +++++++++++++++++++++++++++++++++++++++++------------
 1 file changed, 50 insertions(+), 14 deletions(-)

diff --git a/src/xpath.c b/src/xpath.c
index da1107d43..309150beb 100644
--- a/src/xpath.c
+++ b/src/xpath.c
@@ -219,17 +219,53 @@ str2axis(const char *str, uint32_t str_len)
 }
 
 /**
- * @brief Print the whole expression \p exp to debug output.
+ * @brief Append a string to a dynamic string variable.
+ *
+ * @param[in,out] str String to use.
+ * @param[in,out] size String size.
+ * @param[in,out] used String used size excluding terminating zero.
+ * @param[in] format Message format.
+ * @param[in] ... Message format arguments.
+ */
+static void
+print_expr_str(char **str, size_t *size, size_t *used, const char *format, ...)
+{
+    int p;
+    va_list ap;
+
+    va_start(ap, format);
+
+    /* try to append the string */
+    p = vsnprintf(*str + *used, *size - *used, format, ap);
+
+    if ((unsigned)p >= *size - *used) {
+        /* realloc */
+        *str = ly_realloc(*str, *size + p + 1);
+        *size += p + 1;
+
+        /* restart ap */
+        va_end(ap);
+        va_start(ap, format);
+
+        /* print */
+        p = vsnprintf(*str + *used, *size - *used, format, ap);
+    }
+
+    *used += p;
+    va_end(ap);
+}
+
+/**
+ * @brief Print the whole expression @p exp to debug output.
  *
  * @param[in] exp Expression to use.
  */
 static void
 print_expr_struct_debug(const struct lyxp_expr *exp)
 {
-    char *tmp;
+    char *buf = NULL;
     uint32_t i, j;
-    FILE *fp;
-    size_t s;
+    size_t size = 0, used = 0;
 
     if (!exp || (ly_ll < LY_LLDBG)) {
         return;
@@ -237,21 +273,21 @@ print_expr_struct_debug(const struct lyxp_expr *exp)
 
     LOGDBG(LY_LDGXPATH, "expression \"%s\":", exp->expr);
     for (i = 0; i < exp->used; ++i) {
-        fp = open_memstream(&tmp, &s);
-        fprintf(fp, "\ttoken %s, in expression \"%.*s\"", lyxp_token2str(exp->tokens[i]), exp->tok_len[i],
-                &exp->expr[exp->tok_pos[i]]);
+        print_expr_str(&buf, &size, &used, "\ttoken %s, in expression \"%.*s\"",
+                lyxp_token2str(exp->tokens[i]), exp->tok_len[i], &exp->expr[exp->tok_pos[i]]);
+
         if (exp->repeat && exp->repeat[i]) {
-            fprintf(fp, " (repeat %d", exp->repeat[i][0]);
+            print_expr_str(&buf, &size, &used, " (repeat %d", exp->repeat[i][0]);
             for (j = 1; exp->repeat[i][j]; ++j) {
-                fprintf(fp, ", %d", exp->repeat[i][j]);
+                print_expr_str(&buf, &size, &used, ", %d", exp->repeat[i][j]);
             }
-            fprintf(fp, ")");
+            print_expr_str(&buf, &size, &used, ")");
         }
-        fflush(fp);
-        LOGDBG(LY_LDGXPATH, tmp);
-        fclose(fp);
-        free(tmp);
+        LOGDBG(LY_LDGXPATH, buf);
+        used = 0;
     }
+
+    free(buf);
 }
 
 #ifndef NDEBUG