wallet: Warn on unexpected EOF while salvaging wallet

Check for EOF before every getline, and warn when reading gets to EOF
before the end of the data.

Stricter error checking could shed more light on issues such as #7463
and #7379.

src/wallet/db.cpp

@@ -165,6 +165,11 @@ CDBEnv::VerifyResult CDBEnv::Verify(const std::string& strFile, bool (*recoverFu
     return (fRecovered ? RECOVER_OK : RECOVER_FAIL);
 }
 
+/* End of headers, beginning of key/value data */
+static const char *HEADER_END = "HEADER=END";
+/* End of key/value data */
+static const char *DATA_END = "DATA=END";
+
 bool CDBEnv::Salvage(const std::string& strFile, bool fAggressive, std::vector<CDBEnv::KeyValPair>& vResult)
 {
     LOCK(cs_db);
@@ -199,18 +204,29 @@ bool CDBEnv::Salvage(const std::string& strFile, bool fAggressive, std::vector<C
     // DATA=END
 
     string strLine;
-    while (!strDump.eof() && strLine != "HEADER=END")
+    while (!strDump.eof() && strLine != HEADER_END)
         getline(strDump, strLine); // Skip past header
 
     std::string keyHex, valueHex;
-    while (!strDump.eof() && keyHex != "DATA=END") {
+    while (!strDump.eof() && keyHex != DATA_END) {
         getline(strDump, keyHex);
-        if (keyHex != "DATA=END") {
+        if (keyHex != DATA_END) {
+            if (strDump.eof())
+                break;
             getline(strDump, valueHex);
+            if (valueHex == DATA_END) {
+                LogPrintf("CDBEnv::Salvage: WARNING: Number of keys in data does not match number of values.\n");
+                break;
+            }
             vResult.push_back(make_pair(ParseHex(keyHex), ParseHex(valueHex)));
         }
     }
 
+    if (keyHex != DATA_END) {
+        LogPrintf("CDBEnv::Salvage: WARNING: Unexpected end of file while reading salvage output.\n");
+        return false;
+    }
+
     return (result == 0);
 }