I'm trying to use some Native Code to create Gifs. I draw the images using paint, creating a few strokes, click save and the image drawn gets saved to a JPG format. when I click create Gif it takes all the images and starts creating a gif. This is when I get a Fatal Signal 11 and the app restarts.
I use native code so I have a backtrace of the crash:
I/DEBUG(95): backtrace:
I/DEBUG(95): #00 pc 00002a04 /lib/libgifflen.so (NeuQuant::learn()+239)
I/DEBUG(95): #01 pc 00002b9d /lib/libgifflen.so (NeuQuant::quantise(DIB*, DIB*, int, int, int)+84)
I/DEBUG(95): #02 pc 00002d41 lib/libgifflen.so (Java_com_stay_gif_GifEncoder_addFrame+208)
I/DEBUG(95): #03 pc 0001deb0 /system/lib/libdvm.so (dvmPlatformInvoke+112)
I/DEBUG(95): #04 pc 0004d103 /system/lib/libdvm.so (dvmCallJNIMethod(unsigned int const*, JValue*, Method const*, Thread*)+394)
I/DEBUG(95): #05 pc 0004f21f /system/lib/libdvm.so (dvmResolveNativeMethod(unsigned int const*, JValue*, Method const*, Thread*)+174)
I/DEBUG(95): #06 pc 000272e0 /system/lib/libdvm.so
I/DEBUG(95): #07 pc 0002bbe8 /system/lib/libdvm.so (dvmInterpret(Thread*, Method const*, JValue*)+180)
I/DEBUG(95): #08 pc 0005fb37 /system/lib/libdvm.so (dvmInvokeMethod(Object*, Method const*, ArrayObject*, ArrayObject*, ClassObject*, bool)+374)
I/DEBUG(95): #09 pc 000670e5 /system/lib/libdvm.so
I/DEBUG(95): #10 pc 000272e0 /system/lib/libdvm.so
I/DEBUG(95): #11 pc 0002bbe8 /system/lib/libdvm.so (dvmInterpret(Thread*, Method const*, JValue*)+180)
I/DEBUG(95): #12 pc 0005f871 /system/lib/libdvm.so (dvmCallMethodV(Thread*, Method const*, Object*, bool, JValue*, std::__va_list)+272)
I/DEBUG(95): #13 pc 000496f3 /system/lib/libdvm.so
I/DEBUG(95): #14 pc 00048581 /system/lib/libandroid_runtime.so
I/DEBUG(95): #15 pc 00049637 /system/lib/libandroid_runtime.so (android::AndroidRuntime::start(char const*, char const*)+390)
I/DEBUG(95): #16 pc 00000dcf /system/bin/app_process
The code where it crashes:
void NeuQuant::learn()
{
int i,j,b,g,r;
int radius,rad,alpha,step,delta,samplepixels;
//unsigned char *p;
int *p;
unsigned char *lim;
alphadec = 30 + ((samplefac-1)/3);
p = (int*)thepicture;
lim = thepicture + lengthcount;
samplepixels = lengthcount/samplefac;
delta = samplepixels/ncycles;
alpha = initalpha;
radius = initradius;
rad = radius >> radiusbiasshift;
if (rad <= 1) rad = 0;
for (i=0; i<rad; i++)
radpower[i] = alpha*(((rad*rad - i*i)*radbias)/(rad*rad));
//fprintf(stderr,"beginning 1D learning: initial radius=%d\n", rad);
sprintf(s, "samplepixels = %d, rad = %d, a=%d, ad=%d, d=%d", samplepixels, rad, alpha, alphadec, delta);
__android_log_write(ANDROID_LOG_VERBOSE, "gifflen",s);
if ((lengthcount%prime1) != 0) step = prime1;
else {
if ((lengthcount%prime2) !=0) step = prime2;
else {
if ((lengthcount%prime3) !=0) step = prime3;
else step = prime4;
}
}
i = 0;
while (i < samplepixels)
{
/* b = p[0] << netbiasshift;
g = p[1] << netbiasshift;
r = p[2] << netbiasshift;*/
b = (((*p)) & 0xff) << netbiasshift;
g = (((*p) >> 8) & 0xff) << netbiasshift;
r = (((*p) >> 16) & 0xff) << netbiasshift;
j = contest(b, g, r);
altersingle(alpha,j,b,g,r); //these crashes
if (rad) alterneigh(rad,j,b,g,r); // alter neighbours
p += step;
if (p >= (int *)lim) p -= lengthcount;
i++;
if (i%delta == 0)
{
alpha -= alpha / alphadec;
radius -= radius / radiusdec;
rad = radius >> radiusbiasshift;
if (rad <= 1) rad = 0;
for (j=0; j<rad; j++)
radpower[j] = alpha*(((rad*rad - j*j)*radbias)/(rad*rad));
}
}
//sprintf(s, "final alpha = %f", ((float)alpha)/initalpha);
// __android_log_write(ANDROID_LOG_VERBOSE, "gifflen",s);
}
Thx to the Log I found out that the error happens in NeuQuant::learn(), did some debugs and it crashes on this exact line b = (((*p)) & 0xff) << netbiasshift;.
The Crash doesnt happen always, sometimes I get a gif and everything works, but sometimes it crashes at b = (((*p)) & 0xff) << netbiasshift;.
I did some more debuging and I found out that when it crashes on b = (((*p)) & 0xff) << netbiasshift; it doesnt crash when it enters the first time, it crashes like after the 30 check of b = (((*p)) & 0xff) << netbiasshift;.
Anyone know what might be the problem?
p
becomes an invalid reference, leading to segmentation fault because of your pointer arithmetic. – Peahen