3
試圖用libjpeg從一些原始數據寫入一個jpeg文件。用libjpeg寫一個jpeg(seg故障)
它觸發分段錯誤在jpeg_start_compress()
這裏是代碼的相關部分:
void write_sub_image(char *filename, int start, int end)
{
struct jpeg_compress_struct cinfo;
unsigned char *stride;
JSAMPROW row_pointer[1];
unsigned long new_width = end-start;
int i;
FILE *fp;
stride = (unsigned char *)malloc(new_width * 3);
fp = fopen(filename, "w+");
jpeg_create_compress(&cinfo);
jpeg_stdio_dest(&cinfo, fp);
cinfo.image_width = new_width;
cinfo.image_height = height;
cinfo.input_components = 3;
cinfo.in_color_space = JCS_RGB;
jpeg_set_defaults(&cinfo);
jpeg_start_compress(&cinfo, FALSE);
for (i=0; i<height; i++) {
memcpy (stride, image + (start + i * width) * 3, new_width * 3);
row_pointer[0] = stride;
jpeg_write_scanlines(&cinfo, &stride, 1);
}
jpeg_finish_compress(&cinfo);
jpeg_destroy_compress(&cinfo);
fclose(fp);
}
的問題是不符合的memcpy,它甚至不會在for循環.. 。只是在_start_compress崩潰。
如果相關,系統是Ubuntu 10.10。
是否檢查`new_width`和`height`是有效的(即> 0)? – OrangeDog 2011-01-12 00:26:27
事實上,這不能是整個代碼,因爲'高度'沒有聲明。 – OrangeDog 2011-01-12 00:27:54