/*
* Copyright � 2007 Alistair Crooks.  All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
*    notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
*    notice, this list of conditions and the following disclaimer in the
*    documentation and/or other materials provided with the distribution.
* 3. The name of the author may not be used to endorse or promote
*    products derived from this software without specific prior written
*    permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS
* OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
* GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include <sys/types.h>

#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <fuse.h>
#include <regex.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include "virtdir.h"
#include "defs.h"

static int               verbose; /* how chatty are we? */

static virtdir_t         pci;

/* a device node describes the device that is printed in the dmesg */
typedef struct devicenode_t {
       char    *dev;           /* device name */
       int      devlen;        /* length of name */
       char    *parent;        /* its parent device name */
       int      parentlen;     /* length of parent name */
       char    *descr;         /* description of the device itself */
       int      descrlen;      /* length of description */
       int      p;             /* device node subscript of parent */
       int      dir;           /* nonzero if this is a directory */
} devicenode_t;

DEFINE_ARRAY(devices_t, devicenode_t);

static devices_t        devices;


/* perform the stat operation */
/* if this is the root, then just synthesise the data */
static int
dmesgfs_getattr(const char *path, struct stat *st)
{
       virt_dirent_t   *ep;

       if (strcmp(path, "/") == 0) {
               (void) memset(st, 0x0, sizeof(*st));
               st->st_mode = (S_IFDIR | 0755);
               st->st_nlink = 2;
               return 0;
       }
       if ((ep = virtdir_find(&pci, path, strlen(path))) == NULL) {
               return -ENOENT;
       }
       switch(ep->type) {
       case 'f':
               (void) memcpy(st, &pci.file, sizeof(*st));
               st->st_size = ep->tgtlen;
               st->st_mode = S_IFREG | 0644;
               break;
       case 'd':
               (void) memcpy(st, &pci.dir, sizeof(*st));
               break;
       case 'l':
               (void) memcpy(st, &pci.lnk, sizeof(*st));
               st->st_size = ep->tgtlen;
               st->st_mode = S_IFLNK | 0755;
               break;
       }
       st->st_ino = virtdir_offset(&pci, ep) + 10;
       return 0;
}

/* readdir operation */
static int
dmesgfs_readdir(const char *path, void *buf, fuse_fill_dir_t filler,
             off_t offset, struct fuse_file_info * fi)
{
       static VIRTDIR  *dirp;
       virt_dirent_t   *dp;

       if (offset == 0) {
               if ((dirp = openvirtdir(&pci, path)) == NULL) {
                       return 0;
               }
               filler(buf, ".", NULL, 0);
               filler(buf, "..", NULL, 0);
       }
       while ((dp = readvirtdir(dirp)) != NULL) {
               if (filler(buf, dp->d_name, NULL, 0) != 0) {
                       return 0;
               }
       }
       closevirtdir(dirp);
       dirp = NULL;
       return 0;
}

/* open the file in the file system */
static int
dmesgfs_open(const char *path, struct fuse_file_info * fi)
{
       return 0;
}

/* read the file's contents in the file system */
static int
dmesgfs_read(const char *path, char *buf, size_t size, off_t offset,
          struct fuse_file_info * fi)
{
       virt_dirent_t   *ep;

       if ((ep = virtdir_find(&pci, path, strlen(path))) == NULL) {
               return -ENOENT;
       }
       if (ep->tgt == NULL) {
               return -ENOENT;
       }
       (void) memcpy(buf, &ep->tgt[offset], size);
       return ep->tgtlen;
}

/* fill in the statvfs struct */
static int
dmesgfs_statfs(const char *path, struct statvfs *st)
{
       (void) memset(st, 0x0, sizeof(*st));
       return 0;
}

/* read the symbolic link */
static int
dmesgfs_readlink(const char *path, char *buf, size_t size)
{
       virt_dirent_t   *ep;

       if ((ep = virtdir_find(&pci, path, strlen(path))) == NULL) {
               return -ENOENT;
       }
       if (ep->tgt == NULL) {
               return -ENOENT;
       }
       (void) strlcpy(buf, ep->tgt, size);
       return 0;
}

/* operations struct */
static struct fuse_operations dmesgfs_oper = {
       .getattr = dmesgfs_getattr,
       .readlink = dmesgfs_readlink,
       .readdir = dmesgfs_readdir,
       .open = dmesgfs_open,
       .read = dmesgfs_read,
       .statfs = dmesgfs_statfs
};

/* save `n' chars of `s' in malloc'd memory */
static char *
strnsave(const char *s, int n)
{
       char    *cp;

       if (n < 0) {
               n = strlen(s);
       }
       NEWARRAY(char, cp, n + 1, "strnsave", exit(EXIT_FAILURE));
       (void) memcpy(cp, s, n);
       cp[n] = 0x0;
       return cp;
}

/* find a device in the device node tree */
static int
finddev(const char *s, int len, int updir)
{
       int     i;

       for (i = 0 ; i < devices.c ; i++) {
               if (strncmp(devices.v[i].dev, s, len) == 0 &&
                   devices.v[i].devlen == len) {
                       if (updir) {
                               devices.v[i].dir = 1;
                       }
                       return i;
               }
       }
       return -1;
}

/* add a device to the device node tree */
static void
add_dev(const char *dev, int len, const char *parent, int parentlen, const char *descr, int descrlen)
{
       int     d;

       if ((d = finddev(dev, len, 0)) < 0) {
               ALLOC(devicenode_t, devices.v, devices.size, devices.c, 10, 10, "add_dev", exit(EXIT_FAILURE));
               devices.v[devices.c].dev = strnsave(dev, len);
               devices.v[devices.c].devlen = len;
               devices.v[devices.c].parent = strnsave(parent, parentlen);
               devices.v[devices.c].parentlen = parentlen;
               devices.v[devices.c].descr = strnsave(descr, descrlen);
               devices.v[devices.c].descrlen = descrlen;
               devices.c += 1;
       }
}

/* print the parent device pathname */
static int
pparent(int d, char *buf, size_t size)
{
       int     cc;

       if (d != 0) {
               cc = pparent(devices.v[d].p, buf, size);
               size -= cc;
       }
       (void) strlcat(buf, "/", size);
       (void) strlcat(buf, devices.v[d].dev, size - 1);
       return devices.v[d].devlen + 1;
}

#define NEXUS_DESCRIPTION       "Nexus - the root of everything"

/* build up a fuse_tree from the information in the database */
static int
build_tree(virtdir_t *tp, const char *nexus, char type)
{
       struct stat      dir;
       struct stat      f;
       regmatch_t       matchv[10];
       regex_t          r;
       FILE            *pp;
       char             buf[BUFSIZ];
       int              i;
       int              p;

       (void) stat(".", &dir);
       (void) memcpy(&f, &dir, sizeof(f));
       f.st_mode = S_IFREG | 0644;
       if (regcomp(&r, "^([a-z0-9]+) at ([a-z0-9]+)(.*)", REG_EXTENDED) != 0) {
               warn("can't compile regular expression\n");
               return 0;
       }
       if ((pp = popen("dmesg", "r")) == NULL) {
               return 0;
       }
       add_dev(nexus, strlen(nexus), nexus, strlen(nexus), NEXUS_DESCRIPTION,
               strlen(NEXUS_DESCRIPTION));
       while (fgets(buf, sizeof(buf), pp) != NULL) {
               if (type == 'l') {
                       buf[strlen(buf) - 1] = 0x0;
               }
               if (regexec(&r, buf, 10, matchv, 0) == 0) {
                       add_dev(&buf[matchv[1].rm_so],
                               matchv[1].rm_eo - matchv[1].rm_so,
                               &buf[matchv[2].rm_so],
                               matchv[2].rm_eo - matchv[2].rm_so,
                               buf,
                               matchv[0].rm_eo - matchv[0].rm_so);
               }
       }
       printf("%d devices\n", devices.c);
       (void) pclose(pp);
       for (i = 0 ; i < devices.c ; i++) {
               if ((p = finddev(devices.v[i].parent, devices.v[i].parentlen, 1)) < 0) {
                       warn("No parent device for %s\n", devices.v[i].dev);
               }
               devices.v[i].p = p;
       }
       for (i = 0 ; i < devices.c ; i++) {
               pparent(i, buf, sizeof(buf));
               virtdir_add(tp, buf, strlen(buf),
                       (devices.v[i].dir) ? 'd' : type,
                       devices.v[i].descr, devices.v[i].descrlen);
               if (devices.v[i].dir) {
                       (void) strlcat(buf, "/", sizeof(buf));
                       (void) strlcat(buf, "Description", sizeof(buf));
                       virtdir_add(tp, buf, strlen(buf), type,
                               devices.v[i].descr, devices.v[i].descrlen);
               }
               if (verbose) {
                       printf("dmesgfs: adding %s `%s' -> `%s'\n",
                               (type == 'l') ? "symbolic link" : "file",
                               buf, devices.v[i].descr);
               }
               buf[0] = 0x0;
       }
       return 1;
}

int
main(int argc, char **argv)
{
       char    *nexus;
       char     type;
       int      i;

       nexus = NULL;
       type = 'l';
       while ((i = getopt(argc, argv, "fln:v")) != -1) {
               switch(i) {
               case 'f':
                       type = 'f';
                       break;
               case 'l':
                       type = 'l';
                       break;
               case 'n':
                       nexus = optarg;
                       break;
               case 'v':
                       verbose += 1;
                       break;
               }
       }
       if (!build_tree(&pci, (nexus) ? nexus : "mainbus0", type)) {
               exit(EXIT_FAILURE);
       }
       return fuse_main(argc, argv, &dmesgfs_oper, NULL);
}

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