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/* libguestfs Erlang bindings.
* Copyright (C) 2011-2020 Red Hat Inc.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#include <config.h>
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <string.h>
#include <errno.h>
#include <arpa/inet.h>
#include <ei.h>
#include "error.h"
#include "full-read.h"
#include "full-write.h"
#include "guestfs.h"
#include "guestfs-utils.h"
#include "actions.h"
guestfs_h *g;
/* This stops things getting out of hand, but also lets us detect
* protocol problems quickly.
*/
#define MAX_MESSAGE_SIZE (32*1024*1024)
static char *read_message (void);
static void write_reply (ei_x_buff *);
int
main (void)
{
char *buff;
int index;
int version;
ei_x_buff reply;
/* This process has a single libguestfs handle. If the Erlang
* system creates more than one handle, then more than one of these
* processes will be running.
*/
g = guestfs_create ();
if (g == NULL)
error (EXIT_FAILURE, 0, "could not create guestfs handle");
guestfs_set_error_handler (g, NULL, NULL);
while ((buff = read_message ()) != NULL) {
if (ei_x_new_with_version (&reply) != 0)
error (EXIT_FAILURE, 0, "could not allocate reply buffer");
index = 0;
if (ei_decode_version (buff, &index, &version) != 0)
error (EXIT_FAILURE, 0, "could not interpret the input message");
if (dispatch (&reply, buff, &index) != 0)
error (EXIT_FAILURE, 0, "could not decode input data or encode reply message");
free (buff);
write_reply (&reply);
ei_x_free (&reply);
}
guestfs_close (g);
exit (EXIT_SUCCESS);
}
/* The Erlang port always sends the length of the buffer as 4
* bytes in network byte order, followed by the message buffer.
*/
static char *
read_message (void)
{
uint32_t buf;
size_t size;
char *r;
errno = 0;
if (full_read (0, &buf, 4) != 4) {
if (errno == 0) /* ok - closed connection normally */
return NULL;
else
error (EXIT_FAILURE, errno, "read message size");
}
size = ntohl (buf);
if (size > MAX_MESSAGE_SIZE)
error (EXIT_FAILURE, 0, "message larger than MAX_MESSAGE_SIZE");
r = malloc (size);
if (r == NULL)
error (EXIT_FAILURE, errno, "malloc");
if (full_read (0, r, size) != size)
error (EXIT_FAILURE, errno, "read message content");
return r;
}
static void
write_reply (ei_x_buff *buff)
{
size_t size = buff->index;
unsigned char sbuf[4];
sbuf[0] = (size >> 24) & 0xff;
sbuf[1] = (size >> 16) & 0xff;
sbuf[2] = (size >> 8) & 0xff;
sbuf[3] = size & 0xff;
if (full_write (1, sbuf, 4) != 4)
error (EXIT_FAILURE, errno, "write message size");
if (full_write (1, buff->buff, size) != size)
error (EXIT_FAILURE, errno, "write message content");
}
/* Note that all published Erlang code/examples etc uses strncmp in
* a buggy way. This is the right way to do it.
*/
int
atom_equals (const char *atom, const char *name)
{
const size_t namelen = strlen (name);
const size_t atomlen = strlen (atom);
if (namelen != atomlen) return 0;
return strncmp (atom, name, atomlen) == 0;
}
int
make_error (ei_x_buff *buff, const char *funname)
{
if (ei_x_encode_tuple_header (buff, 3) != 0) return -1;
if (ei_x_encode_atom (buff, "error") != 0) return -1;
if (ei_x_encode_string (buff, guestfs_last_error (g)) != 0) return -1;
if (ei_x_encode_long (buff, guestfs_last_errno (g)) != 0) return -1;
return 0;
}
int
unknown_function (ei_x_buff *buff, const char *fun)
{
if (ei_x_encode_tuple_header (buff, 2) != 0) return -1;
if (ei_x_encode_atom (buff, "unknown") != 0) return -1;
if (ei_x_encode_atom (buff, fun) != 0) return -1;
return 0;
}
int
unknown_optarg (ei_x_buff *buff, const char *funname, const char *optargname)
{
if (ei_x_encode_tuple_header (buff, 2) != 0) return -1;
if (ei_x_encode_atom (buff, "unknownarg") != 0) return -1;
if (ei_x_encode_atom (buff, optargname) != 0) return -1;
return 0;
}
int
make_string_list (ei_x_buff *buff, char **r)
{
size_t i, size;
for (size = 0; r[size] != NULL; ++size);
if (ei_x_encode_list_header (buff, size) != 0) return -1;
for (i = 0; r[i] != NULL; ++i)
if (ei_x_encode_string (buff, r[i]) != 0) return -1;
if (size > 0)
if (ei_x_encode_empty_list (buff) != 0) return -1;
return 0;
}
/* Make a hash table. The number of elements returned by the C
* function is always even.
*/
int
make_table (ei_x_buff *buff, char **r)
{
size_t i, size;
for (size = 0; r[size] != NULL; ++size);
if (ei_x_encode_list_header (buff, size/2) != 0) return -1;
for (i = 0; r[i] != NULL; i += 2) {
if (ei_x_encode_tuple_header (buff, 2) != 0) return -1;
if (ei_x_encode_string (buff, r[i]) != 0) return -1;
if (ei_x_encode_string (buff, r[i+1]) != 0) return -1;
}
if (size/2 > 0)
if (ei_x_encode_empty_list (buff) != 0) return -1;
return 0;
}
int
make_bool (ei_x_buff *buff, int r)
{
if (r)
return ei_x_encode_atom (buff, "true");
else
return ei_x_encode_atom (buff, "false");
}
int
decode_string_list (const char *buff, int *index, char ***res)
{
int i, size;
char **r;
if (ei_decode_list_header (buff, index, &size) != 0)
error (EXIT_FAILURE, 0, "not a list");
r = malloc ((size+1) * sizeof (char *));
if (r == NULL)
error (EXIT_FAILURE, errno, "malloc");
for (i = 0; i < size; i++)
if (decode_string (buff, index, &r[i]) != 0) return -1;
// End of a list is encoded by an empty list, so skip it
if (size > 0 && buff[*index] == ERL_NIL_EXT)
(*index)++;
r[size] = NULL;
*res = r;
return 0;
}
int
decode_string (const char *buff, int *index, char **res)
{
size_t size;
if (decode_binary (buff, index, res, &size) != 0) return -1;
(*res)[size] = 0;
return 0;
}
int
decode_binary (const char *buff, int *index, char **res, size_t *size)
{
int index0;
int size0;
char *r;
index0 = *index;
if (ei_decode_iodata (buff, index, &size0, NULL) != 0) return -1;
r = malloc (size0+1); // In case if it's called from decode_string ()
if (r == NULL)
error (EXIT_FAILURE, errno, "malloc");
*index = index0;
if (ei_decode_iodata (buff, index, NULL, r) != 0) {
free (r);
return -1;
}
*res = r;
*size = (size_t) size0;
return 0;
}
int
decode_bool (const char *buff, int *index, int *res)
{
char atom[MAXATOMLEN];
if (ei_decode_atom (buff, index, atom) != 0) return -1;
if (atom_equals (atom, "true"))
*res = 1;
else
*res = 0;
return 0;
}
int
decode_int (const char *buff, int *index, int *res)
{
unsigned char c;
long l;
long long ll;
if (ei_decode_char (buff, index, (char *) &c) == 0) {
// Byte integers in Erlang are to be treated as unsigned
*res = (int) c;
return 0;
}
if (ei_decode_long (buff, index, &l) == 0) {
/* XXX check for overflow */
*res = (int) l;
return 0;
}
if (ei_decode_longlong (buff, index, &ll) == 0) {
/* XXX check for overflow */
*res = (int) ll;
return 0;
}
/* XXX fail in some way */
return -1;
}
int
decode_int64 (const char *buff, int *index, int64_t *res)
{
unsigned char c;
long l;
long long ll;
if (ei_decode_char (buff, index, (char *) &c) == 0) {
// Byte integers in Erlang are to be treated as unsigned
*res = (int64_t) c;
return 0;
}
if (ei_decode_long (buff, index, &l) == 0) {
*res = (int64_t) l;
return 0;
}
if (ei_decode_longlong (buff, index, &ll) == 0) {
/* XXX check for overflow */
*res = (int64_t) ll;
return 0;
}
/* XXX fail in some way */
return -1;
}
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