2 files changed, 25 insertions, 14 deletions

diff --git a/src/MTS_IO_CellularRadio.cpp b/src/MTS_IO_CellularRadio.cpp
index 19f1b7b..49a2b32 100644
--- a/src/MTS_IO_CellularRadio.cpp
+++ b/src/MTS_IO_CellularRadio.cpp
@@ -21,6 +21,7 @@
 #include "mts/MTS_IO_CellularRadio.h"
 
 #include <unistd.h>
+#include <sys/stat.h>
 
 #include <mts/MTS_IO_MccMncTable.h>
 #include <mts/MTS_Thread.h>
@@ -1138,10 +1139,21 @@ ICellularRadio::CODE CellularRadio::sendData(const char* pData, size_t nBytes) {
         return ERROR;
     }
 
+    // This limit comes from the Connection::write implementation. Otherwise we can get overflows.
+    const size_t maxInt32 = INT32_MAX;    // iSize parameter type in Connection::write
+    const size_t maxUInt32 = UINT32_MAX;  // return value type in Connection::write
+    const size_t nSizeLimit = std::min(maxInt32, maxUInt32);
+
+    if (nBytes > nSizeLimit) {
+        printError("RADIO| Chunks larger than %d bytes are not supported", nSizeLimit);
+        return INVALID_ARGS;
+    }
+
+    // Now we can ignore conversion and overflow warnings emitted by compiler.
     int32_t iResult;
     iResult = m_apIo->write(pData, nBytes);
 
-    if(iResult == -1) {
+    if(iResult != static_cast<int32_t>(nBytes)) {
         printError("RADIO| Failed to send data to radio");
         return ERROR;
     }
@@ -1272,21 +1284,20 @@ ICellularRadio::CODE CellularRadio::getFileSize(int fd, size_t& nBytes) {
     CODE rc = FAILURE;
 
     do {
-        ssize_t dScrollPos;
-        dScrollPos = lseek(fd, 0, SEEK_SET);
-        if (dScrollPos < 0) {
-            printError("Failed to seek to the start of the file: %d", errno);
+        struct stat fileStatus;
+
+        // On success, zero is returned. On error, -1 is returned, and errno is set appropriately.
+        if (fstat(fd, &fileStatus) < 0) {
+            printError("Failed to determine file size: %d", errno);
             break;
         }
 
-        dScrollPos = lseek(fd, 0, SEEK_END);
-        if (dScrollPos < 0) {
-            printError("Failed to determine the file size: %d", errno);
+        if (fileStatus.st_size < 0) {
+            printError("Failed to determine file size, file size is negative: %d", fileStatus.st_size);
             break;
         }
 
-        nBytes = static_cast<size_t>(dScrollPos);
-
+        nBytes = static_cast<size_t>(fileStatus.st_size);
         rc = SUCCESS;
 
     } while (false);
diff --git a/src/MTS_IO_TelitRadio.cpp b/src/MTS_IO_TelitRadio.cpp
index a82004c..8c7e174 100644
--- a/src/MTS_IO_TelitRadio.cpp
+++ b/src/MTS_IO_TelitRadio.cpp
@@ -943,7 +943,7 @@ ICellularRadio::CODE TelitRadio::fumoWriteGroupsABD(int fd, ICellularRadio::Upda
     printTrace("File size: %d bytes and %d chunks", dPayloadLength, nChunks);
     printTrace("Starting file upload...");
 
-    rc = startWrite();
+    rc = startFotaWriteABD();
     if (rc != SUCCESS) {
         return rc;
     }
@@ -980,12 +980,12 @@ ICellularRadio::CODE TelitRadio::fumoWriteGroupsABD(int fd, ICellularRadio::Upda
     }
 
     // send +++
-    abortWrite();
+    abortFotaWriteABD();
     return rc;
 }
 
 
-ICellularRadio::CODE TelitRadio::startWrite() {
+ICellularRadio::CODE TelitRadio::startFotaWriteABD() {
     const std::vector<std::string> vBailStrings{ ICellularRadio::RSP_CONNECT, ICellularRadio::RSP_ERROR };
     const int dTimeout = 1000; //ms
     std::string sCommand, sResult;
@@ -1001,7 +1001,7 @@ ICellularRadio::CODE TelitRadio::startWrite() {
     return SUCCESS;
 }
 
-ICellularRadio::CODE TelitRadio::abortWrite() {
+ICellularRadio::CODE TelitRadio::abortFotaWriteABD() {
     /*
      * To prevent the “+++” from being mistaken for data, the following sequence should be followed:
      * 1) Do not input any character within 1s or longer before inputting “+++”.