Fix compiler warnings

library.properties

@@ -1,5 +1,5 @@
 name=Adafruit GPS Library
-version=1.7.4
+version=1.7.5
 author=Adafruit
 maintainer=Adafruit <info@adafruit.com>
 sentence=An interrupt-based GPS library for no-parsing-required use

src/Adafruit_GPS.cpp

@@ -351,7 +351,8 @@ char Adafruit_GPS::read(void) {
   }
   // Serial.print(c);
 
-  currentline[lineidx++] = c;
+  currentline[lineidx] = c;
+  lineidx = lineidx + 1;
   if (lineidx >= MAXLINELENGTH)
     lineidx = MAXLINELENGTH -
               1; // ensure there is someplace to put the next received character

src/NMEA_build.cpp

@@ -565,7 +565,14 @@ char *Adafruit_GPS::build(char *nmea, const char *thisSource,
 
   addChecksum(nmea); // Successful completion
   if (!noCRLF) { // Add Carriage Return and Line Feed to comply with NMEA-183
-    sprintf(nmea, "%s\r\n", nmea);
+    size_t len = strlen(nmea);
+    char *nmeaWithCRLF =
+        (char *)malloc(len + 3); // +2 for \r\n, +1 for null terminator
+    if (nmeaWithCRLF) {
+      strcpy(nmeaWithCRLF, nmea);   // Copy original string
+      strcat(nmeaWithCRLF, "\r\n"); // Append \r\n
+      return nmeaWithCRLF;          // return pointer to finished product
+    }
   }
   return nmea; // return pointer to finished product
 }
@@ -590,5 +597,22 @@ void Adafruit_GPS::addChecksum(char *buff) {
     cs ^= buff[i];
     i++;
   }
-  sprintf(buff, "%s*%02X", buff, cs);
+
+  // Calculate the needed buffer size: original length + 3 (*XX) + 1 (null
+  // terminator)
+  int neededSize = strlen(buff) + 4;
+  char *tempBuffer = (char *)malloc(neededSize);
+
+  if (tempBuffer != NULL) {
+    // Use snprintf to safely format the string with the checksum
+    snprintf(tempBuffer, neededSize, "%s*%02X", buff, cs);
+
+    // Copy the formatted string back to the original buffer
+    // Note: Make sure the original buffer is large enough to hold the new
+    // string.
+    strcpy(buff, tempBuffer);
+
+    // Free the allocated memory to avoid memory leaks
+    free(tempBuffer);
+  }
 }