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FS.c
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FS.c
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/*
FUSE: Filesystem in Userspace
Copyright (C) 2001-2007 Miklos Szeredi <[email protected]>
This program can be distributed under the terms of the GNU GPL.
See the file COPYING.
gcc -Wall FS.c `pkg-config fuse --cflags --libs` -o FS
Version 2.0
Modified By: Ponpoorani Ravichandran
Date: 11/27/2014
Updates: Implemented a file system that manages processes in system.
*/
#define FUSE_USE_VERSION 26
#define BUFF_SIZE 100000
#include <fuse.h>
#include <stdio.h>
#include <string.h>
#include <errno.h>
#include <unistd.h>
#include <sys/types.h>
#include <dirent.h>
#include <fcntl.h>
static const char *proc_path = "/proc/";
static const char *hello_str = "Hello World!\n";
static const char *myproc_path = "/myproc";
void ls_Dir(const char *name, int level, void *buf, fuse_fill_dir_t filler);
int is_Proc(const char *p);
char* read_ProcInfo(const char *filename);
static int FS_getattr(const char *path, struct stat *stbuf) {
int res = 0;
printf("\n**************** In getAttr *********************");
memset(stbuf, 0, sizeof(struct stat));
if (strcmp(path, "/") == 0) {
stbuf->st_mode = S_IFDIR | 0755;
stbuf->st_nlink = 2;
} else if (strcmp(path, myproc_path) == 0) {
stbuf->st_mode = S_IFREG | 0444;
stbuf->st_nlink = 1;
stbuf->st_size = strlen(hello_str);
} else if (is_Proc(path)) {
stbuf->st_mode = S_IFREG | 0444;
stbuf->st_nlink = 1;
stbuf->st_size = strlen(read_ProcInfo(path));
}
else
res = -ENOENT; // No such file or directory
return res;
}
static int FS_readdir(const char *path, void *buf, fuse_fill_dir_t filler,
off_t offset, struct fuse_file_info *fi) {
printf("\n**************** In readdir *********************");
(void) offset;
(void) fi;
if (strcmp(path, "/") != 0)
return -ENOENT; // No such file or directory
filler(buf, ".", NULL, 0);
filler(buf, "..", NULL, 0);
// list all the processes' names
ls_Dir(proc_path, 0, buf, filler);
return 0;
}
static int FS_open(const char *path, struct fuse_file_info *fi) {
printf("\n**************** In Open *********************");
if (!is_Proc(path + 1))
return -ENOENT; // No such file or directory
if ((fi->flags & 3) != O_RDONLY)
return -EACCES; // Restricted access
return 0;
}
static int FS_read(const char *path, char *buf, size_t size, off_t offset,
struct fuse_file_info *fi) {
printf("\n**************** In read *********************");
size_t len;
(void) fi;
if(is_Proc(path + 1)) {
const char *p = read_ProcInfo(path);
len = strlen(p);
if (offset < len) {
if (offset + size > len)
size = len - offset;
memcpy(buf, p + offset, size);
}
else {
size = 0;
}
return size;
}
else {
return 0;
}
}
static struct fuse_operations FS_oper = {
.getattr = FS_getattr,
.readdir = FS_readdir,
.open = FS_open,
.read = FS_read,
};
// list the content of given direcotry
void ls_Dir(const char *name, int level, void *buf, fuse_fill_dir_t filler) {
printf("\n**************** In listdir *********************");
DIR *dir;
struct dirent *entry;
if (!(dir = opendir(name)) || !(entry = readdir(dir)))
return;
do {
// To check if file type is directory and a process directory (contains numbers in name)
if ( (entry->d_type == DT_DIR) && (is_Proc(entry->d_name)) ) {
char path[1024];
int len = snprintf(path, sizeof(path)-1, "%s/%s", name, entry->d_name);
path[len] = 0;
filler(buf, entry->d_name, NULL, 0);
}
} while ( (entry = readdir(dir)) );
closedir(dir);
}
// Check whether it is a process folder by checking whether string contains numbers.
int is_Proc(const char *p) {
while(*p) {
if (*p != '/' && (*p < '0' || *p > '9')) return 0;
else p++;
}
return 1;
}
// read process info
char* read_ProcInfo(const char *filename) {
printf("\n**************** In ReadProcInfo *********************");
// generate full path
char full_path[100] = "";
strcat(full_path, "/proc");strcat(full_path, filename);strcat(full_path, "/status");
char source[BUFF_SIZE + 1];
FILE *fp = fopen(full_path, "r");
if (fp != NULL) {
size_t newLen = fread(source, sizeof(char), BUFF_SIZE, fp);
if (newLen == 0) {
fputs("Error reading file", stderr);
} else {
source[++newLen] = '\0';
}
fclose(fp);
}
return source;
}
// Main entry point of application / program.
int main(int argc, char *argv[])
{
return fuse_main(argc, argv, &FS_oper, NULL);
}