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/**
* dircnt.c - a fast file-counting program.
*
* Written 2015-02-06 by Christopher Schultz as a programming demonstration
* for a StackOverflow answer:
* https://stackoverflow.com/questions/1427032/fast-linux-file-count-for-a-large-number-of-files/28368788#28368788
*
* This code is licensed under the Apache License 2.0. Please read the file
* LICENSE for more information.
*
* Please see the README.md file for compilation and usage instructions.
*
* Thanks to FlyingCodeMonkey, Gary R. Van Sickle, and Jonathan Leffler for
* various suggestions and improvements to the original code. Any additional
* contributors can be found by looking at the GitHub revision history from
* this point forward..
*/
#include <stdio.h>
#include <dirent.h>
#include <string.h>
#include <stdlib.h>
#include <limits.h>
#include <sys/stat.h>
#if defined(WIN32) || defined(_WIN32)
#define PATH_SEPARATOR '\\'
#else
#define PATH_SEPARATOR '/'
#endif
#define EXIT_REACHED_LIMIT 0x01
/* A custom structure to hold separate file and directory counts */
struct filecount {
unsigned long dirs;
unsigned long files;
};
/*
* counts the number of files and directories in the specified directory.
*
* path - relative pathname of a directory whose files should be counted
* counts - pointer to struct containing file/dir counts
*/
void count(char *path, struct filecount *counts) {
DIR *dir; /* dir structure we are reading */
struct dirent *ent; /* directory entry currently being processed */
char subpath[PATH_MAX]; /* buffer for building complete subdir and file names */
struct stat statbuf; /* buffer for stat() info. A call to lstat() might be
required even if _DIRENT_HAVE_D_TYPE is true
because ent->d_type might be DT_UNKNOWN */
int isdir; /* flag for a directory entry being a directory */
#ifdef DEBUG
fprintf(stderr, "Opening dir %s\n", path);
#endif
dir = opendir(path);
/* opendir failed... file likely doesn't exist or isn't a directory */
if(NULL == dir) {
perror(path);
return;
}
while((ent = readdir(dir))) {
if (strlen(path) + 1 + strlen(ent->d_name) > PATH_MAX) {
fprintf(stdout, "path too long (%ld) %s%c%s", (strlen(path) + 1 + strlen(ent->d_name)), path, PATH_SEPARATOR, ent->d_name);
return;
}
isdir = 0; /* reset isdir flag */
#ifdef DEBUG
fprintf(stderr, "Considering %s%c%s\n", path, PATH_SEPARATOR, ent->d_name);
#endif /* DEBUG */
/* Use dirent.d_type if present, otherwise use stat() */
#if ( defined ( _DIRENT_HAVE_D_TYPE ) && !PREFER_STAT)
if(DT_UNKNOWN == ent->d_type) {
/* Must perform lstat() anyway */
#ifdef DEBUG
fprintf(stderr, "Dirent type is DT_UNKNOWN, must perform lstat()\n");
#endif /* DEBUG */
sprintf(subpath, "%s%c%s", path, PATH_SEPARATOR, ent->d_name);
if(lstat(subpath, &statbuf)) {
perror(subpath);
return;
}
if(S_ISDIR(statbuf.st_mode)) {
#ifdef DEBUG
fprintf(stderr, "Determined %s is a directory via lstat(1)\n", subpath);
#endif /* DEBUG */
isdir = 1;
}
} else if(DT_DIR == ent->d_type) {
#ifdef DEBUG
fprintf(stderr, "Determined %s%c%s is a directory via dirent\n", path, PATH_SEPARATOR, ent->d_name);
#endif /* DEBUG */
isdir = 1;
}
#else
sprintf(subpath, "%s%c%s", path, PATH_SEPARATOR, ent->d_name);
if(lstat(subpath, &statbuf)) {
perror(subpath);
return;
}
if(S_ISDIR(statbuf.st_mode)) {
#ifdef DEBUG
fprintf(stderr, "S_ISDIR=%d, mode bits=%x\n", S_ISDIR(statbuf.st_mode), statbuf.st_mode);
fprintf(stderr, "Determined %s is a directory via lstat(2)\n", subpath);
#endif /* DEBUG */
isdir = 1;
}
#endif /* if defined _DIRENT_HAVE_D_TYPE, etc. */
#ifdef DEBUG
fprintf(stderr, "name=%s, isdir=%d\n", ent->d_name, isdir);
#endif
if(isdir) {
/* Skip "." and ".." directory entries... they are not "real" directories */
if(0 == strcmp("..", ent->d_name) || 0 == strcmp(".", ent->d_name)) {
/* fprintf(stderr, "This is %s, skipping\n", ent->d_name); */
} else {
if(ULONG_MAX == counts->dirs) {
fprintf(stderr, "Reached maximum number of directories to count (%lu) after %lu files\n", counts->dirs, counts->files);
exit(EXIT_REACHED_LIMIT);
}
sprintf(subpath, "%s%c%s", path, PATH_SEPARATOR, ent->d_name);
counts->dirs++;
count(subpath, counts);
}
} else {
if(ULONG_MAX == counts->files) {
fprintf(stderr, "Reached maximum number of files to count (%lu) after %lu directories\n", counts->files, counts->dirs);
exit(EXIT_REACHED_LIMIT);
}
counts->files++;
}
}
#ifdef DEBUG
fprintf(stderr, "Closing dir %s\n", path);
#endif
closedir(dir);
}
int main(int argc, char *argv[]) {
struct filecount counts;
char *dir;
counts.files = 0;
counts.dirs = 0;
if(argc > 1)
dir = argv[1];
else
dir = ".";
#ifdef DEBUG
#if PREFER_STAT
fprintf(stderr, "Compiled with PREFER_STAT. Using lstat()\n");
#elif defined ( _DIRENT_HAVE_D_TYPE )
fprintf(stderr, "Using dirent.d_type\n");
#else
fprintf(stderr, "Don't have dirent.d_type, falling back to using lstat()\n");
#endif
#endif
count(dir, &counts);
/* If we found nothing, this is probably an error which has already been printed */
if(0 < counts.files || 0 < counts.dirs) {
printf("%s contains %lu files and %lu directories\n", dir, counts.files, counts.dirs);
}
return 0;
}
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