mc/vfs/sfs.c

/*
 * Single File fileSystem
 *
 * Copyright 1998 Pavel Machek, distribute under GPL
 *
 * This defines whole class of filesystems which contain single file
 * inside. It is somehow similar to extfs, except that extfs makes
 * whole virtual trees and we do only single virtual files. 
 *
 * If you want to gunzip something, you should open it with #ugz
 * suffix, DON'T try to gunzip it yourself.
 *
 * Namespace: exports vfs_sfs_ops, shell (FIXME) */

#include <config.h>
#include <errno.h>
#include <sys/types.h>
#include <unistd.h>
#include <stdio.h>
#include <string.h>
#include <fcntl.h>

#include "utilvfs.h"

#include "vfs.h"
#include "local.h"

/* This is needed, or libvfs.so will lack symbol shell. Should look up who requires it */
char *shell = "/bin/sh";

struct cachedfile {
    char *name, *cache;
    uid_t uid;
    struct cachedfile *next;
};

static struct cachedfile *head;

#define MAXFS 32
static int sfs_no = 0;
static char *sfs_prefix[ MAXFS ];
static char *sfs_command[ MAXFS ];
static int sfs_flags[ MAXFS ];
#define F_1 1
#define F_2 2
#define F_NOLOCALCOPY 4
#define F_FULLMATCH 8

static int uptodate (char *name, char *cache)
{
    return 1;
}

static int vfmake (vfs *me, char *name, char *cache)
{
    char *inpath, *op;
    int w;
    char pad [10240];
    char *s, *t = pad;
    int was_percent = 0;

    vfs_split (name, &inpath, &op);
    if ((w = (*me->which) (me, op)) == -1)
        vfs_die ("This cannot happen... Hopefully.\n");

    if ((sfs_flags[w] & F_1) || (!strcmp (name, "/"))) ; else return -1;
    /*    if ((sfs_flags[w] & F_2) || (!inpath) || (!*inpath)); else return -1; */
    if (!(sfs_flags[w] & F_NOLOCALCOPY)) {
        s = mc_getlocalcopy (name);
	if (!s)
	    return -1;
        name = name_quote (s, 0);
	g_free (s);
    } else 
        name = name_quote (name, 0);
#define COPY_CHAR if (t-pad>sizeof(pad)) { g_free (name); return -1; } else *t++ = *s;
#define COPY_STRING(a) if ((t-pad)+strlen(a)>sizeof(pad)) { g_free (name); return -1; } else { strcpy (t, a); t+= strlen(a); }
    for (s = sfs_command[w]; *s; s++) {
        if (was_percent) {

	    char *ptr = NULL;
	    was_percent = 0;

	    switch (*s) {
	    case '1': ptr = name; break;
	    case '2': ptr = op + strlen (sfs_prefix[w]); break;
	    case '3': ptr = cache; break;
	    case '%': COPY_CHAR; continue; 
	    }
	    COPY_STRING (ptr);
	} else {
	    if (*s == '%')
		was_percent = 1;
	    else
		COPY_CHAR;
	}
    }
    g_free (name);

    if (my_system (EXECUTE_AS_SHELL | EXECUTE_SETUID | EXECUTE_WAIT, "/bin/sh", pad)) {
	return -1;
    }

    return 0; /* OK */
}

static char *
redirect (vfs *me, char *name)
{
    struct cachedfile *cur = head;
    uid_t uid = vfs_uid;
    char *cache;
    int handle;

    while (cur){
        if ((!strcmp (name, cur->name)) &&
	    (uid == cur->uid) &&
	    (uptodate (cur->name, cur->cache)))
		/* FIXME: when not uptodate, we might want to kill cache
		 * file immediately, not to wait until timeout. */ {
		vfs_stamp (&vfs_sfs_ops, cur);
		return cur->cache;
	}
	cur = cur->next;
    }

    cache = tempnam (NULL, "sfs");
    handle = open (cache, O_RDWR | O_CREAT | O_EXCL, 0600);
    if (handle == -1) {
	g_free (cache);
	return "/SOMEONE_PLAYING_DIRTY_TMP_TRICKS_ON_US";
    }

    close (handle);

    if (!vfmake (me, name, cache)){
	cur = g_new (struct cachedfile, 1);
	cur->name = g_strdup (name);
	cur->cache = cache;
	cur->uid = uid;
	cur->next = head;
	head = cur;

	vfs_add_noncurrent_stamps (&vfs_sfs_ops, (vfsid) head, NULL);
	vfs_rm_parents (NULL);

	return cache;
    }
    g_free (cache);
    return "/I_MUST_NOT_EXIST";
}

static void *
sfs_open (vfs *me, char *path, int flags, int mode)
{
    int *sfs_info;
    int fd;

    path = redirect (me, path);
    fd = open (path, flags, mode);
    if (fd == -1)
	return 0;

    sfs_info = g_new (int, 1);
    *sfs_info = fd;
    
    return sfs_info;
}

static int sfs_stat (vfs *me, char *path, struct stat *buf)
{
    path = redirect (me, path);
    return stat (path, buf);
}

static int sfs_lstat (vfs *me, char *path, struct stat *buf)
{
    path = redirect (me, path);
#ifndef HAVE_STATLSTAT
    return lstat (path,buf);
#else
    return statlstat (path, buf);
#endif
}

static int sfs_chmod (vfs *me, char *path, int mode)
{
    path = redirect (me, path);
    return chmod (path, mode);
}

static int sfs_chown (vfs *me, char *path, int owner, int group)
{
    path = redirect (me, path);
    return chown (path, owner, group);
}

static int sfs_utime (vfs *me, char *path, struct utimbuf *times)
{
    path = redirect (me, path);
    return utime (path, times);
}

static int sfs_readlink (vfs *me, char *path, char *buf, int size)
{
    path = redirect (me, path);
    return readlink (path, buf, size);
}

static vfsid sfs_getid (vfs *me, char *path, struct vfs_stamping **parent)
{	/* FIXME: what should I do? */
    vfs *v;
    vfsid id;
    struct vfs_stamping *par;
    struct cachedfile *cur = head;

    while (cur) {
        if ((!strcmp( path, cur->name )) &&
	    (vfs_uid == cur->uid))
	    break;
	cur = cur->next;
    }
    if (!cur)
        vfs_die( "sfs_getid of noncached thingie?" );

    *parent = NULL;

    {
        char *path2 = g_strdup (path);
	v = vfs_split (path2, NULL, NULL);	/* Strip suffix which led to this being sfs */
	v = vfs_split (path2, NULL, NULL);	/* ... and learn whoever was the parent system */
	id = (*v->getid) (v, path2, &par);
	g_free (path2);
    }

    if (id != (vfsid)-1) {
        *parent = g_new (struct vfs_stamping, 1);
        (*parent)->v = v;
        (*parent)->id = id;
        (*parent)->parent = par;
        (*parent)->next = NULL;
    }
    return (vfsid) cur;
}

static void sfs_free (vfsid id)
{
    struct cachedfile *which = (struct cachedfile *) id;
    struct cachedfile *cur, *prev;

    for (cur = head, prev = 0; cur && cur != which; prev = cur, cur = cur->next)
	;
    if (!cur)
    	vfs_die( "Free of thing which is unknown to me\n" );
    unlink (cur->cache);

    if (prev)
	prev->next = cur->next;
    else
	head = cur->next;
}

static void sfs_fill_names (vfs *me, void (*func)(char *))
{
    struct cachedfile *cur = head;

    while (cur){
	(*func)(cur->name);
	cur = cur->next;
    }
}

static int sfs_nothingisopen (vfsid id)
{
    /* FIXME: Investigate whether have to guard this like in
       the other VFSs (see fd_usage in extfs) -- Norbert */
    return 1;
}

static char *sfs_getlocalcopy (vfs *me, char *path)
{
    path = redirect (me, path);
    return g_strdup (path);
}

static int sfs_ungetlocalcopy (vfs *me, char *path, char *local, int has_changed)
{
    g_free(local);
    return 0;
}

static int sfs_init (vfs *me)
{
    FILE *cfg = fopen (LIBDIR "extfs/sfs.ini", "r");

    if (!cfg){
        fprintf (stderr, "Warning: " LIBDIR "extfs/sfs.ini not found\n");
        return 0;
    }

    sfs_no = 0;
    while (sfs_no < MAXFS){
        char key[256];
	char *c, *semi = NULL, flags = 0;
	int i;

        if (!fgets (key, 250, cfg))
	    break;

	if (*key == '#')
	    continue;

	for (i = 0; i < strlen (key); i++)
	    if ((key[i]==':') || (key[i]=='/')){
		semi = key+i;
		if (key [i] == '/'){
		    key [i] = 0;
		    flags |= F_FULLMATCH;
		}
		break;
	    }

	if (!semi){
	    fprintf (stderr, "Warning: Invalid line %s in sfs.ini.\n", key);
	    continue;
	}

	c = semi + 1;
	while ((*c != ' ') && (*c != 9)) {
	    switch (*c) {
	    case '1': flags |= F_1; break;
	    case '2': flags |= F_2; break;
	    case 'R': flags |= F_NOLOCALCOPY; break;
	    default:
	      fprintf (stderr, "Warning: Invalid flag %c in sfs.ini line %s.\n", *c, key);
	    }	    
	    c++;
	}
	c++;
	*(semi+1) = 0;
	if ((semi = strchr (c, '\n')))
	    *semi = 0;

	sfs_prefix [sfs_no] = g_strdup (key);
	sfs_command [sfs_no] = g_strdup (c);
	sfs_flags [sfs_no] = flags;
	sfs_no++;
    }
    fclose (cfg);
    return 1;
}

static void
sfs_done (vfs *me)
{
    int i;

    for (i = 0; i < sfs_no; i++){
        g_free (sfs_prefix [i]);
	g_free (sfs_command [i]);
	sfs_prefix [i] = sfs_command [i] = NULL;
    }
    sfs_no = 0;
}

static int
sfs_which (vfs *me, char *path)
{
    int i;

    for (i = 0; i < sfs_no; i++)
        if (sfs_flags [i] & F_FULLMATCH) {
	    if (!strcmp (path, sfs_prefix [i]))
	        return i;
	} else
	    if (!strncmp (path, sfs_prefix [i], strlen (sfs_prefix [i])))
	        return i;

    
    return -1;
}

vfs vfs_sfs_ops = {
    NULL,	/* This is place of next pointer */
    "Signle file filesystems",
    F_EXEC,	/* flags */
    NULL,	/* prefix */
    NULL,	/* data */
    0,		/* errno */
    sfs_init,
    sfs_done,
    sfs_fill_names,
    sfs_which,

    sfs_open,
    local_close,
    local_read,
    NULL,
    
    NULL,
    NULL,
    NULL,
    NULL,
    NULL,

    sfs_stat,
    sfs_lstat,
    local_fstat,

    sfs_chmod,
    sfs_chown,
    sfs_utime,

    sfs_readlink,
    NULL,
    NULL,
    NULL,

    NULL,
    NULL,
    local_errno,
    local_lseek,
    NULL,
    
    sfs_getid,
    sfs_nothingisopen,
    sfs_free,
    
    sfs_getlocalcopy,
    sfs_ungetlocalcopy,
    
    NULL,
    NULL,
    NULL,
    NULL

#ifdef HAVE_MMAP
    ,local_mmap,
    local_munmap
#endif
};