Calculating size of Directory in C - c

Question

I want to calculate the size of the directory (path) recursively. In my current code I have a function that identifies if it's a directory or file, if it's a directory it calls the function with the subdirectory (file) and if it's a file it adds to the totalSize variable. However, my current code doesn't return anything meaning that there is an error somewhere.
here is my code -
#include <sys/types.h>
#include <dirent.h>
#include <stdio.h>
#include <errno.h>
#include <unistd.h>
#include <sys/stat.h>
void getsize(const char *path,int* totalSize);
int main()
{
int total = 0;
char path [] = "C:\\Users\\abbas\\Desktop\\Leetcode airplane";
getsize(path,&total);
printf("%d",total);
return total;
}
void getsize(const char *path,int* totalSize)
{
struct dirent *pDirent;
struct stat buf;
struct stat info;
DIR *pDir;
int exists;
char str[100];
pDir = opendir (path);
while ((pDirent = readdir(pDir)) != NULL)
{
stat(pDirent->d_name,&info);
if(S_ISDIR(info.st_mode))
{
strcpy(str,path);
strcat(str,"/");
strcat(str,pDirent->d_name);
getsize(str,totalSize);
}
else
{
strcpy(str,path);
strcat(str,"/");
strcat(str,pDirent->d_name);
exists = stat(str,&buf);
if (exists < 0)
{
continue;
}
else
{
(*totalSize) += buf.st_size;
}
}
}
closedir(pDir);
}

Answer 1

Include string.h.
The arbitrary fixed sizestr[100] is problematic. If you are on Linux include linux/limits.h and use str[PATH_MAX] or even better pathconf(path, _PC_NAME_MAX). In either case you should either ensure the buffer is big enough (using snprintf() for instance), or dynamically allocate the buffer.
You need to exclude . and .. otherwise you end up with an infinite loop (path/../path/..).
stat(pDirent->d_name,&info) fails as you need to stat() path/pDirect->d_name not just pDirect->d_name.
(not fixed) Maybe snprintf(path2, sizeof path2, "%s%s%s", path, PATH_SEP, pDirenv->d_name) instead of strcpy() and strcat()?
Check return values of functions otherwise you are wasting time.
No point of doing two stat() calls on the same path so just use (*totalSize) += buf.st_size;.
(not fixed) On Windows, consider using _stat64() with the address of a struct __stat64 (#AndrewHenle).
I assume you only want the size of files.
(not fixed) It would be more natural if getsize() returned the size instead of using int *totalSize out parameter.
(not fixed) Consider using nftw() (or the older ftw()) to walk the tree.
Note that program now accept path via command line for testing purposes.
#include <dirent.h>
#include <errno.h>
#include <linux/limits.h>
#include <stdio.h>
#include <string.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>
const char PATH_SEP =
#ifdef _WIN32
"\\";
#else
"/";
#endif
void getsize(const char *path,int *totalSize) {
struct dirent *pDirent;
DIR *pDir = opendir (path);
while ((pDirent = readdir(pDir)) != NULL) {
if(
!strcmp(pDirent->d_name, ".") ||
!strcmp(pDirent->d_name, "..")
)
continue;
char path2[PATH_MAX];
strcpy(path2, path);
strcat(path2, PATH_SEP);
strcat(path2, pDirent->d_name);
struct stat info;
if(stat(path2, &info) == -1) {
perror("stat");
return;
}
if(S_ISDIR(info.st_mode))
getsize(path2, totalSize);
else if(S_ISREG(info.st_mode))
(*totalSize) += info.st_size;
}
closedir(pDir);
}
int main(argc, char *argv[]) {
if(argc != 2) {
printf("usage: your_program path\n");
return 1;
}
int total = 0;
getsize(argv[1], &total);
printf("%d\n",total);
}
and example test:
$ mkdir -p 1/2
$ dd if=/dev/zero of=1/file count=123
123+0 records in
123+0 records out
62976 bytes (63 kB, 62 KiB) copied, 0.000336838 s, 187 MB/s
$ dd if=/dev/zero of=1/2/file count=234
234+0 records in
234+0 records out
119808 bytes (120 kB, 117 KiB) copied, 0.0015842 s, 75.6 MB/s
$ echo $((62976 + 119808))
182784
$ ./your_program 1
182784

Answer 2

I think the major error of your code lies in the recursive logic.
To quote pp.183 of The C Programming Language:
Each directory always contains entries for itself, called ".",
and its parent, ".."; these must be skipped, or the program will
loop forever.
Therefore, maybe you can try adding the following if test
at the beginning of the while loop:
while ((pDirent = readdir(pDir)) != NULL)
{
if (strcmp(pDirent->d_name, ".") == 0
|| strcmp(pDirent->d_name, "..") == 0)
continue; /* skip self and parent */
/* ... */
}
Still, there might be other errors, but I think this one is the most significant.

Answer 3

Practice safe coding.
Below risks buffer overflow.
// Risky
strcpy(str,path);
strcat(str,"/");
strcat(str,pDirent->d_name);
Had code done,
int len = snprintf(str, sizeof str, "%s/%s", path, pDirent->d_name);
if (len < 0 || (unsigned) len >= sizeof str) {
fprintf(stderr, "Path too long %s/%s\n", path, pDirent->d_name);
exit (-1);
}
Then the code would have readily errored out do to recursion on "." and ".." and led to OP's self-discovery of a key problem.
This make for faster code production and more resilient code. Saves OP time.