I’m reading float data in from a file and Valgrind gives the error “Invalid read of size 4”. I’m a new user of Valgrind and don’t understand why I get this error.
My code is:
int main()
{
N = 220928;
std::vector<std::complex<float>> rxTmp(N);
FILE *fid;
char fn[] = "data.bin";
fid = fopen(fn, "rb");
std::size_t ct = fread(&rxTmp[0],4,N,fid);
fclose(fid);
return 0;
}
The code compiles and executes without error but Valgrind gives the invalid read.
==41376== 1 errors in context 1 of 1:
==41376== Invalid read of size 4
==41376== at 0x77E0180: fread (in /usr/lib64/libc-2.17.so)
==41376== by 0x423F67: main (main.cc:77)
==41376== Address 0x0 is not stack'd, malloc'd or (recently) free'd
where line 77 is the fread statement.
The file size is correct; there are 220928*4 floats in the file.
Reading in any value less than N results in the same Valgrind error.
I tried changing the number of elements read to less than the number of elements in the file and still get the Valgrind error
6
I was not able reproduce the issue after adding basic error checking of the fopen() call. I also changed the fread() size argument from 4 to sizeof rxTmp[0] which is 8 on my system.
#include <complex>
#include <cstdio>
#include <iostream>
#include <vector>
int main() {
std::size_t N = 220928;
std::vector<std::complex<float> > rxTmp(N);
FILE *fid = fopen("data.bin", "rb");
if(!fid) {
std::cerr << "Could not open filen";
return 1; // fclose(NULL) is undefined
}
std::size_t ct = fread(&rxTmp[0],sizeof rxTmp[0],N,fid);
fclose(fid);
return 0;
}
2