From a686beb9a7976d790e2ee6caf14747138899529c Mon Sep 17 00:00:00 2001
From: oakfire <oakfire@163.com>
Date: Tue, 30 Aug 2022 14:22:58 +0800
Subject: [PATCH] fix: #1696  mg_json_get() bugs.

---
 mongoose.c       | 19 ++++++++++++++++---
 test/unit_test.c | 13 +++++++++++++
 2 files changed, 29 insertions(+), 3 deletions(-)

diff --git a/mongoose.c b/mongoose.c
index d94ce7ef..d811e7f3 100644
--- a/mongoose.c
+++ b/mongoose.c
@@ -2517,10 +2517,15 @@ int mg_json_get(struct mg_str json, const char *path, int *toklen) {
     MG_DBGP('-');
     switch (expecting) {
       case S_VALUE:
+        if ( depth == ed && ei == ci && c != '[' && path[pos] == '[' ) return MG_JSON_NOT_FOUND;
         if (depth == ed) j = i;
         if (c == '{') {
           if (depth >= (int) sizeof(nesting)) return MG_JSON_TOO_DEEP;
-          if (depth == ed && path[pos] == '.') ed++, pos++;
+          if (depth == ed && (ci == ei || ci < 0) && path[pos] == '.') {
+            ed++, pos++;
+            ci = -1;
+            ei = -1;
+          }
           nesting[depth++] = c;
           expecting = S_KEY;
           break;
@@ -2537,6 +2542,7 @@ int mg_json_get(struct mg_str json, const char *path, int *toklen) {
           nesting[depth++] = c;
           break;
         } else if (c == ']' && depth > 0) {  // Empty array
+          if (depth == ed) ci = -1;
           MG_EOO(']');
         } else if (c == 't' && i + 3 < len && memcmp(&s[i], "true", 4) == 0) {
           i += 3;
@@ -2556,7 +2562,11 @@ int mg_json_get(struct mg_str json, const char *path, int *toklen) {
           return MG_JSON_INVALID;
         }
         MG_CHECKRET('V');
-        if (depth == ed && ei >= 0) ci++;
+        if (depth == ed && ei >= 0) {
+          ci++;
+          if (ci > ei) return MG_JSON_NOT_FOUND;
+        }
+
         expecting = S_COMMA_OR_EOO;
         break;
 
@@ -2602,7 +2612,10 @@ int mg_json_get(struct mg_str json, const char *path, int *toklen) {
           // MG_CHECKRET('C');
         } else if (c == ']' || c == '}') {
           MG_EOO('O');
-          if (depth == ed && ei >= 0) ci++;
+          if (depth == ed && ei >= 0) {
+            ci++;
+            if (ci > ei) return MG_JSON_NOT_FOUND;
+          }
         } else {
           return MG_JSON_INVALID;
         }
diff --git a/test/unit_test.c b/test/unit_test.c
index a34842e6..58948996 100644
--- a/test/unit_test.c
+++ b/test/unit_test.c
@@ -2495,6 +2495,19 @@ static void test_json(void) {
     ASSERT(mg_json_get_long(json, "$.a[0]", -42) == 1);
     ASSERT(mg_json_get_long(json, "$.ab", -42) == 2);
     ASSERT(mg_json_get_long(json, "$.ac", -42) == -42);
+
+    json = mg_str("{\"a\":[],\"b\":[1,2]}");
+    ASSERT(mg_json_get_long(json, "$.a[0]", -42) == -42);
+    ASSERT(mg_json_get_long(json, "$.b[0]", -42) == 1);
+    ASSERT(mg_json_get_long(json, "$.b[1]", -42) == 2);
+    ASSERT(mg_json_get_long(json, "$.b[2]", -42) == -42);
+    json = mg_str("[{\"a\":1,\"b\":2},{\"a\":3, \"b\":4}]");
+    ASSERT(mg_json_get_long(json, "$[0].a", -42) == 1);
+    ASSERT(mg_json_get_long(json, "$[0].b", -42) == 2);
+    ASSERT(mg_json_get_long(json, "$[1].a", -42) == 3);
+    ASSERT(mg_json_get_long(json, "$[1].b", -42) == 4);
+    ASSERT(mg_json_get_long(json, "$[2].a", -42) == -42);
+
   }
 }