Pointer being freed was not allocated, Abort trap: 6 - c

Question

I'm not proficient in C programming so please excuse me if this isn't a strong question. In the following code, I can only allocate memory to samplesVecafter obtaining the value of nsamplepts, but I need to return the vector samplesVec to the main for further use (not yet coded). However, I'm getting the following error:
Error in Terminal Window:
ImportSweeps(3497,0x7fff7b129310) malloc: * error for object 0x7fdaa0c03af8: pointer being freed was not allocated
* set a breakpoint in malloc_error_break to debug
Abort trap: 6
I'm using Mac OS X Mavericks with the gcc compiler. Thanks for any help.
*EDITED!!! AFTER VALUABLE INPUTS FROM COMMENTATORS, THE FOLLOWING REPRESENTS A SOLUTION TO THE ORIGINAL PROBLEM (WHICH IS NO LONGER AVAILABLE) *
The following code modification seemed to solve my original questions. Thanks for the valuable inputs everyone!
/* Header Files */
#define LIBAIFF_NOCOMPAT 1 // do not use LibAiff 2 API compatibility
#include <libaiff/libaiff.h>
#include <unistd.h>
#include <stdio.h>
#include <dirent.h>
#include <string.h>
#include <sys/stat.h>
#include <stdlib.h>
#include <math.h>
/* Function Declarations */
void FileSearch(char*, char*, char*, char*, char*);
int32_t *ImportSweeps(char*);
/* Main */
int main()
{
char flag1[2] = "N";
char binname[20] = "bin1"; // dummy assignment
char buildfilename[40] = "SweepR";
char skeletonpath[100] = "/Users/.../Folder name/";
int k, len;
/* Find the sweep to be imported in the directory given by filepath */
FileSearch(skeletonpath, binname, buildfilename, skeletonpath, flag1);
if (strcmp(flag1,"Y")) {
printf("No file found. End of program.\n");
} else {
len = (int) strlen(skeletonpath);
char *filepath = malloc(len);
for (k = 0; k < len; k++) {
filepath[k] = skeletonpath[k];
}
printf("File found! Filepath: %s\n", filepath);
// Proceed to import sweep
int32_t *sweepRfile = ImportSweeps(filepath);
if (sweepRfile) {
printf("Success!\n");
// Do other things with sweepRfile
free(sweepRfile);
}
free(filepath);
}
return 0;
}
/* Sub-Routines */
void FileSearch(char *dir, char *binname, char *buildfilename, char* filepath, char* flag1)
{
DIR *dp;
struct dirent *entry;
struct stat statbuf;
if((dp = opendir(dir)) == NULL) {
fprintf(stderr,"Cannot open directory: %s\n", dir);
return;
}
chdir(dir);
while((entry = readdir(dp)) != NULL) {
lstat(entry->d_name, &statbuf);
if(S_ISDIR(statbuf.st_mode)) {
/* Found a directory, but ignore . and .. */
if(strcmp(".",entry->d_name) == 0 || strcmp("..",entry->d_name) == 0)
continue;
strcpy(binname,entry->d_name);
strcpy(buildfilename,"SweepR");
/* Recurse at a new indent level */
FileSearch(entry->d_name, binname, buildfilename, filepath, flag1);
}
else {
sprintf(buildfilename, "%s%s.aiff", buildfilename, binname);
if (strcmp(entry->d_name,buildfilename)) {
strcpy(buildfilename,"SweepR");
} else {
sprintf(filepath, "%s%s/%s", filepath, binname, buildfilename);
strcpy(flag1,"Y");
break;
}
}
}
chdir("..");
closedir(dp);
}
int32_t *ImportSweeps(char *filepath)
{
char *filepathread = filepath;
/* Initialize files for importing */
AIFF_Ref fileref;
/* Intialize files for getting information about AIFF file */
uint64_t nSamples;
int32_t *samples = NULL;
int32_t *samplesVec = NULL;
int channels, bitsPerSample, segmentSize, ghost, nsamplepts;
double samplingRate;
/* Import Routine */
fileref = AIFF_OpenFile(filepathread, F_RDONLY) ;
if(fileref)
{
// File opened successfully. Proceed.
ghost = AIFF_GetAudioFormat(fileref, &nSamples, &channels, &samplingRate, &bitsPerSample, &segmentSize);
if (ghost < 1)
{
printf("Error getting audio format.\n");
AIFF_CloseFile(fileref); return (int32_t) 0;
}
nsamplepts = ((int) nSamples)*channels;
samples = malloc(nsamplepts * sizeof(int32_t));
samplesVec = malloc(nsamplepts * sizeof(int32_t));
ghost = AIFF_ReadSamples32Bit(fileref, samples, nsamplepts);
if (ghost) {
for (int k = 0; k < nsamplepts; k++) {
samplesVec[k] = *(samples+k);
}
}
free(samples);
AIFF_CloseFile(fileref);
}
return samplesVec;
}

Answer 1

So... as far as I can see... :-)
samplesVec, the return value of ImportSweeps is not initialized, if fileref is false. Automatic (== local) variables have no guarantees on its value if samplesVec are not explicitly initialized - in other words samplesVec could carry any address. If samplesVec is not NULL on luck (which on the other hand might be often the case), you try free a not allocated junk of memory, or by very bad luck an somewhere else allocated one.
If I'm correct with my guess you can easy fix this with:
int32_t *samples;
int32_t *samplesVec = NULL;
It is a good idea anyway to initialize any variable as soon as possible with some meaningful error or dummy value, if you not use it in the very next line. As pointers are horrible beasts, I always NULL them if I don't initialize them with a useful value on declaration.
Edit: Several minor small changes for a readable approximation to English. :-)

Answer 2

If AIFF_OpenFile fails, ImportSweeps returns an undefined value because samplesVec wasn't initialized. If that value is non-NULL, main will try to free it. You can either initialize samplesVec = NULL, or you can reorganize the code as
fileref = AIFF_OpenFile(filepathread, F_RDONLY) ;
if(!fileref) {
{
// print error message here
return NULL;
}
// File opened successfully. Proceed.
...
There are people who will insist a functon that should only have one exit -- they are poorly informed and voicing a faulty dogma handed down from others who are likewise uninformed and dogmatic. The check for error and return above is known as a guard clause. The alternate style, of indenting every time a test succeeds, yields the arrow anti-pattern that is harder to read, harder to modify, and more error prone. See http://blog.codinghorror.com/flattening-arrow-code/ and http://c2.com/cgi/wiki?ArrowAntiPattern for some discussion.