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t_handle and sysmem_newhandle crash help needed

May 21, 2006 | 1:12 am

Hi, I’m trying to read in a text file with sysfile_readtextfile, but I’m running into crashes using sysmem commands. Specifically, the following code (called thru defer_low) crashes:

——————————
void myrecorder_do_open(t_myrecorder* x, t_symbol *s, short ac, t_atom *av) {
t_handle text_handle;
long size;

text_handle = sysmem_newhandle(20000);
size = sysmem_handlesize(text_handle);
}
——————————

When I remove the sysmem_handlesize line it doesn’t crash. I also printed out the text_handle pointer to make sure it wasn’t NULL.

Calls to sysmem_freehandle(&text_handle) crash Max as well.

My plan was to sscanf thru the text_handle after filling it with the contents from a text file. Any suggestions or example code would be greatly appreciated. I’m developing using XCode, running Max 4.5.

-Scott

I’ve already been scouring the archives and only found this example of using t_handles: (which also crashes)

short readtohandle(char *name, short volume, char ***h, long *sizep)
{
t_filehandle fh;
long size;
t_handle space;

if (path_opensysfile(name, volume,&fh, PATH_READ_PERM)) {
error("%s: can’t open", name);
return (1);
}
sysfile_geteof(fh,&size);
if (!(space = sysmem_newhandle(size)))
{
ouchstring("Not enough memory to open %s",name);
return (1);
}
if (sysfile_readtextfile(fh,space,0,TEXT_LB_NATIVE))
{
readerror(name);
sysmem_freehandle(space);
sysfile_close(fh);
return (1);
}
*h = space;
*sizep = sysmem_handlesize(space); // could change in sysfile_readtextfile
sysfile_close(fh);
return (0);
}


May 22, 2006 | 7:21 pm

Hi Scott,

This sounds like it may be a problem with the Mach-O interface
exposed in previous versions of MaxAPI.framework. I would suggest
waiting a little while for a new version of MaxAPI.framework
(sometime in the next month or two) before calling these functions
which are crashing (sysmem_handlesize and sysmem_freehandle). In the
meantime, you could either use Apple APIs for reading files, or use
CodeWarrior. Sorry for the inconvenience.

-Joshua


May 22, 2006 | 8:03 pm

Thanks for the reply, I have since implemented my c-based text reader using the sysmem_newptr allocation function. I’m still not clear on the differences between t_handles and the memory allocated by sysmem_newptr. In any case, my function reads in a text file containing a list of notes, where each line contains things like vel, pitch, length. I’m posting my code since reading text files into max objects using c code (and Xcode) may be useful for others until new frameworks come out. WARNING: this is not "good" code, there is no error checking–a mis-formated input file would reap havoc. The code opens a dialog for the user to pick a file for reading, loads the entire contents into a newly allocated buffer, then parses that buffer line by line using sscanf and the ‘n’ char as a way to find the start and end of lines.

void myrecorder_open(t_myrecorder* x, long arg) {
t_atom myList[1];
SETLONG(myList,arg); defer_low(x,(method)myrecorder_do_open,0,1,myList);
}

void myrecorder_do_open(t_myrecorder* x, t_symbol *s, short ac, t_atom *av) {
unsigned char p = av->a_w.w_long;
// text file contains notes that will be stored into a phrase, pointed to by pp
struct phrase_type * pp = &(x->phrases[p]);
char filename[128];
short pathID;
OSType dstType;
t_filehandle *fh;
char * text_handle;
long size;
int bytes_scanned;
char teststring[128];
long cur_note;
int i, start_of_line;

// note attributes
long onset, time_from_prev, time_till_next, hand;
float vel, pitch;

if (!open_dialog(filename, &pathID, &dstType,0L,0)) {
path_opensysfile(filename, pathID, &fh, READ_PERM);
sysfile_geteof(fh,&size);
post("Storing file into phrase %d", p);
text_handle = sysmem_newptr(size);
if(text_handle) { // successful allocation
if (!sysfile_read(fh, &size, text_handle)) {
// phrase variables to adjust:
pp->count = 0;
pp->current_pos = 0;
pp->total_length = 0;
pp->tempo = 1.0;
pp->current_time = 0.0;
// first read in the top header line and ignore it
i=0;
while(text_handle[i]!=’n')
i++;
i++;
start_of_line = i;

for(i;i
// search for a n character so we know there’s a line
if (text_handle[i]==’n') { // found the end of a line
sscanf(&text_handle[start_of_line],"%d %f %f %d %d %d",&onset,&pitch,
&vel,&time_from_prev,&time_till_next,&hand);
cur_note = pp->count;
pp->notes[cur_note].onset_time = onset;
pp->notes[cur_note].pitch = pitch;
pp->notes[cur_note].vel = vel;
pp->notes[cur_note].time_from_prev = time_from_prev;
pp->notes[cur_note].time_till_next = time_till_next;
pp->notes[cur_note].hand = hand;
pp->count++;
start_of_line = i+1;
}
}

}
else
post ("error reading file");
}
sysmem_freeptr(text_handle);
else {
post("memory allocation failed");
}
sysfile_close(fh);

}
}


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