Intermittent Error when Playing Dynamically Created Sounds

[cdigit]

I don't know if this is a bug or if it's caused by me doing something wrong with C. I don't want to pollute the discussion with basic C issues, so If it is on my side, please let me know and I'll figure it out. This is on macOS. malloc() is used without free() because I'm manually restarting the program after every run.

The Issue:
Happens in ma_malloc when the sound is initialized from file.
malloc: Heap corruption detected, free list is damaged at 0x600000004230 *** Incorrect guard value: 0

The program:
Creates a sound when 'c' is pressed. Starts the sound when 'p' is pressed.
A. Press 'c' to dynamically create a sound then
B. Press 'p' to play the sound. You can press 'p' multiple times to restart the sound.

How to reproduce the issue:

1. Start the program
2. Do actions A then B
3. Stop the program
4. Repeat steps 1-3 about 5-10 times, quickly. (No need to wait for the sound to finish.)

Working Source

#define MA_DEBUG_OUTPUT
#define MINIAUDIO_IMPLEMENTATION
#include "../../../miniaudio/miniaudio.h"
#include <stdio.h>


static ma_engine g_engine;

struct SoundStruct{
    ma_sound * sound;
};

static struct SoundStruct mystruct;

void create(void);
void play(void);

// create sound pointer and assign it to struct
void create(){
   
    printf("\ncreating sound pointer\n");
    ma_sound * pMaSound;
    pMaSound = (ma_sound*) malloc(sizeof(*pMaSound));
    
    if(pMaSound != NULL){
        printf("OK\n");
    }
    mystruct.sound = pMaSound;
  
}

// init ma_sound with sound pointer in struct and play sound
void play(){
    
    char* filePath = "/Users/user1/Downloads/asound.wav";
    ma_data_source* ds = ma_sound_get_data_source(mystruct.sound);
    if(ds == NULL){
        ma_result result = ma_sound_init_from_file(&g_engine, filePath, 0, NULL, NULL, mystruct.sound);
        if (result != MA_SUCCESS) {
            printf("Failed to initialize sound \"%s\".", filePath);
        }
    }

    ma_sound_seek_to_pcm_frame(mystruct.sound, 0);
    ma_sound_start(mystruct.sound);

}

int main(int argc, char** argv)
{
    ma_result result;


    /* The engine needs to be initialized first. */
    result = ma_engine_init(NULL, &g_engine);
    if (result != MA_SUCCESS) {
        printf("Failed to initialize audio engine.");
        return -1;
    }

 
    printf("1. Press c to create then \n");
    printf("2. Press p to play\n");

    char c;
    while( (c = getchar()) !='q' ){
        printf("typed: %c",c);
        if(c=='c'){
            create();
        }
        
        if(c=='p'){
            play();
        }
    }
    
    return 0;
}

[mackron]

Change malloc(sizeof(pMaSound)) to malloc(sizeof(*pMaSound)).

[cdigit]

Thanks, got it. I made those two changes, but there's still an error. It's different and failing faster (after 1 or 2 tries). Here's a tiny video of it in action with the stack trace. The place where it's failing is below.

MA_API ma_uint64 ma_node_get_time(const ma_node* pNode)
{
    if(pNode == NULL {

        return 0;
    }

    return c89atomic_load_64(&((ma_node_base*)pNode)->localTime); //EXC_BAD_ACCESS (code=EXC_I386_GPFLT)
}

[mackron]

Can you post the exact code you're running now.

[cdigit]

Absolutely, here is the exact code I'm running:

#define MA_DEBUG_OUTPUT
#define MINIAUDIO_IMPLEMENTATION
#include "../../../miniaudio/miniaudio.h"
#include <stdio.h>


static ma_engine g_engine;

struct SoundStruct{
    ma_sound * sound;
};
static ma_sound * pp;
static struct SoundStruct mystruct;

void create(void);
void play(void);

// create sound pointer and assign it to struct
void create(){
   
    printf("\ncreating sound pointer\n");
    ma_sound * pMaSound;
    pMaSound = (ma_sound*) malloc(sizeof(*pMaSound));
    
    if(pMaSound != NULL){
        printf("OK\n");
    }
    mystruct.sound = pMaSound;
   // pp = (ma_sound*) malloc(sizeof(*pp));;
  
}

// init ma_sound with sound pointer in struct and play sound
void play(){
    
    char* filePath = "/Users/admin/Downloads/asound.wav";
    ma_data_source* ds = ma_sound_get_data_source(mystruct.sound);
    if(ds == NULL){
        ma_result result = ma_sound_init_from_file(&g_engine, filePath, 0, NULL, NULL, mystruct.sound);
        if (result != MA_SUCCESS) {
            printf("Failed to initialize sound \"%s\".", filePath);
        }
    }

    ma_sound_seek_to_pcm_frame(mystruct.sound, 0);
    ma_sound_start(mystruct.sound);

}

int main(int argc, char** argv)
{
    ma_result result;


    /* The engine needs to be initialized first. */
    result = ma_engine_init(NULL, &g_engine);
    if (result != MA_SUCCESS) {
        printf("Failed to initialize audio engine.");
        return -1;
    }

 
    printf("1. Press c to create then \n");
    printf("2. Press p to play\n");

    char c;
    while( (c = getchar()) !='q' ){
        printf("typed: %c",c);
        if(c=='c'){
            create();
        }
        
        if(c=='p'){
            play();
        }
    }
    
    return 0;
}

[mackron]

You're accessing uninitialized memory. Your malloc() is allocating a block of memory, but contents of that memory is undefined (just random data). You're calling ma_sound_get_data_source() against that undefined buffer which is resulting in a non-null result, which is skipping the ma_sound_init_from_file() step, and then going straight into ma_sound_*() and crashing.

You need a one-to-one relationship between your buffer allocation and ma_sound_init_*(). Don't use ma_sound_get_data_source() to do what you're doing. It looks like you're trying to make it so you only allocate the buffer once? Just move your ma_sound_init_from_file() into create(), and then put a NULL pointer check on in create() instead of play():

void create()
{
    if (mystruct.sound == NULL) {
        // allocate memory...
        // ... then call ma_sound_init_from_file()
    }
}

void play()
{
    if (mystruct.sound == NULL) {
        printf("Cannot play sound because it has not yet been created.\n");
        return;
    }
    ma_sound_seek_to_pcm_frame(mystruct.sound, 0);
    ma_sound_start(mystruct.sound);
}

[cdigit]

This works as expected and wonderfully! Thank you for the insight. I will incorporate the learnings.