Passing char pointer to function ruins pointer - c++

Question

I am having some difficulties with a bluetooth/oled display displaying the right string. The goal is to read data from bluetooth, update a class variable(Music.setArtist()), and then read from that variable later(Music.getArtist()) to draw it using a draw text function.
If i only call drawText once, it works fine. More than one calls in a loop to drawText cause some undefined behavior though, which is usually the second pointer getting overwritten. This causes the pointer in drawText to be null, or some random characters, or something.
This is my music object.
#ifndef Music_h
#define Music_h
class Music {
private:
char *track,*artist,*length, *position;
int progressBar;
bool playing;
public:
Music(char* t, char* a, char* l, char* po, bool pl, int p): track(t), artist(a), length(l), position(po), playing(pl), progressBar(p){};
~Music(){};
char* getLength(){return length;}
char* getPosition(){return position;}
char* getArtist(){return artist;}
char* getTrack(){return track;}
bool getPlaying(){return playing;}
int getProgressBar(){return progressBar;}
void setLength(char * l){length = l;}
void setPosition(char *p){position = p;}
void setArtist(char *a){artist = a;}
void setTrack(char *t){track = t;}
void setPlaying(bool p){playing = p;}
void setProgressBar(int p){progressBar = p;}
};
#endif
This is my drawText function
void Display_obj::drawText(double xPos, double yPos,char str[], int stringSize, uint8_t asciiBuff)
{
bitmapLetter fnt_controller(0,0,0x00,0,0);
bitmapLetter sheldon_alph[0x5A];
fnt_controller.createDictionary(sheldon_alph,6,8);
int startX = xPos;
int startY = yPos;
for (int i=0; i < stringSize; i++){
char charAt = str[i];
uint8_t ascii = (uint8_t)charAt;
if (ascii > 0x60)
{
charAt = charAt & ~(0x20);
ascii = ascii & ~(0x20);
}
int width = sheldon_alph[ascii-asciiBuff].getWidth();
int height = sheldon_alph[ascii-asciiBuff].getHeight();
size_t siz = sheldon_alph[ascii-asciiBuff].getSize();
unsigned char* bitmap = sheldon_alph[ascii-asciiBuff].getLetter();
drawBitmap(startX,startY,width,height,bitmap,siz);
startX = startX - 8;
if (startX <= 0)
{
startX = xPos;
startY = startY+8;
}
}
}
and my main loop looks something like this
Music music("", "", "", "", false, 0);
RideTracking ride("", "", "", "", "", false);
Navigation nav("", "", "", "", "", false);
void loop(){
if (bt.getDataUpdated() == false)
{
bt.recvWithEndMarker(&bt,&music);
}
else
{
//Serial.println(music.getTrack());
musicUpdateTrack(music.getTrack());
//Serial.println(music.getArtist()); --> This returns gibberish. If the above update is commented out, it works.
musicUpdateArtist(music.getArtist());
bt.setDataUpdated(false);
}
}
Ive tried everything i can think of, which was a lot of messing around with pointers and addresses to see if it was allocated correctly. This is the closest ive gotten, but it seems like the drawText breaks the rest of the char pointers i call in the future. I dont believe the issue has to do with flash or SRAM, as both seem to be within normal values. Any help would be greatly appreciated.
EDIT: in my bluetooth object, there are two calls. one is receive the data, and the other updates the object. I originally didnt include this as it looks like data is set correctly. if i dont call drawtext, but just call print statements, the data is correct.
void blue::updateData(Music* music) {
if (getDataUpdated() == true) {
StaticJsonDocument<256> doc;
DeserializationError error = deserializeJson(doc, receivedChars);
else{
char s1[55];
char s2[55];
char s3[15];
char s4[15];
char s5[15];
if(doc["music"]) {
strlcpy(s1, doc["music"]["track"]);
music->setTrack(s1);
strlcpy(s2, doc["music"]["artist"]);
music->setArtist(s2);
strlcpy(s3, doc["music"]["track_length"]);
music->setLength(s3);
strlcpy(s4, doc["music"]["position"]);
music->setPosition(s4);
music->setProgressBar(doc["music"]["progressBar"]);
music->setPlaying(doc["music"]["playing"]);
}
}
void blue::recvWithEndMarker(blue* bt,Music* mu) {
char rc;
while (ble.available() > 0 && getDataUpdated() == false) {
rc = ble.read();;
if (rc != endMarker)
{
receivedChars[ndx] = rc;
ndx++;
if (ndx >= numChars)
{
ndx = numChars - 1;
}
}
else
{
brackets++;
if(brackets != 2)
{
receivedChars[ndx] = rc;
ndx++;
if (ndx >= numChars)
{
ndx = numChars - 1;
}
}
else
{
receivedChars[ndx] = rc;
receivedChars[ndx+1] = '\0'; // terminate the string
ndx = 0;
brackets = 0;
setDataUpdated(true);
}
}
}
bt->updateData(mu);
}

Answer 1

Found it! In the music class, i changed the variables such as *track, to a hardset track[50]. Then, in the set method, i changed it to
void setLength(char * l){
strlcpy(length,l,strlen(l)+1);
}
void setPosition(char *p){
strlcpy(position,p,strlen(p)+1);
}
void setArtist(char *a){
strlcpy(artist,a,strlen(a)+1);
}
void setTrack(char *t){
strlcpy(track,t,strlen(t)+1);
}
Along with a few changes in how its passed, it now works. Thanks! Ive been stuck on this for days.