Permalink
Fetching contributors…
Cannot retrieve contributors at this time
244 lines (226 sloc) 6.25 KB
/*
* pseudo_ipc.c, IPC code for pseudo client/server
*
* Copyright (c) 2008-2010 Wind River Systems, Inc.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the Lesser GNU General Public License version 2.1 as
* published by the Free Software Foundation.
*
* 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 Lesser GNU General Public License for more details.
*
* You should have received a copy of the Lesser GNU General Public License
* version 2.1 along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
*/
#include <stddef.h>
#include <stdlib.h>
#include <stdio.h>
#include <signal.h>
#include <string.h>
#include <unistd.h>
#include <ctype.h>
#include <errno.h>
#include <sys/stat.h>
#include "pseudo.h"
#include "pseudo_ipc.h"
/* Short reads or writes can cause a sigpipe, killing the program, so we
* trap it and report that something happened.
*/
static sig_atomic_t pipe_error = 0;
static void (*old_handler)(int) = SIG_DFL;
static void
sigpipe_trap(int unused __attribute__((unused))) {
pipe_error = 1;
}
static void
ignore_sigpipe(void) {
pipe_error = 0;
old_handler = signal(SIGPIPE, sigpipe_trap);
}
static void
allow_sigpipe(void) {
signal(SIGPIPE, old_handler);
}
#if 0
/* useful only when debugging crazy stuff */
static void
display_msg_header(pseudo_msg_t *msg) {
pseudo_debug(4, "type: %d\n", msg->type);
pseudo_debug(4, "inode: %llu\n", (unsigned long long) msg->ino);
pseudo_debug(4, "uid: %d\n", msg->uid);
pseudo_debug(4, "pathlen: %d\n", (int) msg->pathlen);
if (msg->pathlen) {
pseudo_debug(4, "path: %s\n", msg->path);
}
}
#endif
/*
* send message on fd
* return:
* 0 on success
* >0 on error
* <0 on error suggesting other end is dead
*/
int
pseudo_msg_send(int fd, pseudo_msg_t *msg, size_t len, const char *path) {
int r;
if (!msg)
return 1;
if (fd < 0)
return -1;
if (path) {
pseudo_debug(4, "msg type %d (%s), external path %s, mode 0%o\n",
msg->type, pseudo_op_name(msg->op), path, (int) msg->mode);
if (len == (size_t) -1)
len = strlen(path) + 1;
msg->pathlen = len;
ignore_sigpipe();
r = write(fd, msg, PSEUDO_HEADER_SIZE);
if (r == PSEUDO_HEADER_SIZE) {
r += write(fd, path, len);
}
allow_sigpipe();
pseudo_debug(5, "wrote %d bytes\n", r);
if (pipe_error || (r == -1 && errno == EBADF))
return -1;
return ((size_t) r != PSEUDO_HEADER_SIZE + len);
} else {
pseudo_debug(4, "msg type %d (%s), result %d (%s), path %.*s, mode 0%o\n",
msg->type, pseudo_op_name(msg->op),
msg->result, pseudo_res_name(msg->result),
msg->pathlen, msg->path, (int) msg->mode);
// display_msg_header(msg);
ignore_sigpipe();
r = write(fd, msg, PSEUDO_HEADER_SIZE + msg->pathlen);
allow_sigpipe();
pseudo_debug(5, "wrote %d bytes\n", r);
if (pipe_error || (r == -1 && errno == EBADF))
return -1;
return ((size_t) r != PSEUDO_HEADER_SIZE + msg->pathlen);
}
}
/* attempts to receive a message from fd
* return is allocated message if one is provided
*/
pseudo_msg_t *
pseudo_msg_receive(int fd) {
static pseudo_msg_t *incoming;
static size_t incoming_pathlen;
pseudo_msg_t *newmsg, header;
int r;
if (fd < 0)
return 0;
errno = 0;
r = read(fd, &header, PSEUDO_HEADER_SIZE);
if (r == -1) {
pseudo_debug(2, "read failed: %s\n", strerror(errno));
return 0;
}
if (r < (int) PSEUDO_HEADER_SIZE) {
pseudo_debug(2, "got only %d bytes (%s)\n", r, strerror(errno));
return 0;
}
pseudo_debug(4, "got header, type %d, pathlen %d\n", header.type, (int) header.pathlen);
// display_msg_header(&header);
if (!incoming || header.pathlen >= incoming_pathlen) {
newmsg = pseudo_msg_new(header.pathlen + 128, 0);
if (!newmsg) {
pseudo_diag("Couldn't allocate header for path of %d bytes.\n",
(int) header.pathlen);
return 0;
}
free(incoming);
incoming = newmsg;
incoming_pathlen = header.pathlen + 128;
}
*incoming = header;
if (incoming->pathlen) {
r = read(fd, incoming->path, incoming->pathlen);
if (r < (int) incoming->pathlen) {
pseudo_debug(2, "short read on path, expecting %d, got %d\n",
(int) incoming->pathlen, r);
return 0;
}
/* ensure null termination */
incoming->path[r] = '\0';
}
// display_msg_header(incoming);
return incoming;
}
/* duplicate a message -- currently totally unused */
pseudo_msg_t *
pseudo_msg_dup(pseudo_msg_t *old) {
pseudo_msg_t *newmsg;
if (!old)
return NULL;
newmsg = malloc(sizeof(pseudo_msg_t) + old->pathlen);
if (!newmsg)
return NULL;
memcpy(newmsg, old, sizeof(pseudo_msg_t) + old->pathlen);
return newmsg;
}
/* allocate a message either with pathlen chars of storage or with enough
* storage for path
*/
pseudo_msg_t *
pseudo_msg_new(size_t pathlen, const char *path) {
pseudo_msg_t *newmsg;
if (pathlen) {
newmsg = malloc(sizeof(pseudo_msg_t) + pathlen);
if (newmsg) {
newmsg->pathlen = pathlen;
if (path)
memcpy(newmsg->path, path, pathlen);
newmsg->path[pathlen - 1] = '\0';
}
return newmsg;
} else {
if (!path) {
/* no pathlen, no path == purely informational */
newmsg = malloc(sizeof(pseudo_msg_t));
if (newmsg) {
newmsg->pathlen = 0;
}
return newmsg;
} else {
pathlen = strlen(path) + 1;
newmsg = malloc(sizeof(pseudo_msg_t) + pathlen);
if (newmsg) {
memcpy(newmsg->path, path, pathlen);
newmsg->pathlen = pathlen;
}
return newmsg;
}
}
}
/* The following functions populate messages from statbufs and vice versa.
* It is intentional that copying a message into a stat doesn't touch nlink;
* the nlink value was not stored in the database (it is in the message at
* all only so the server can do sanity checks).
*/
void
pseudo_msg_stat(pseudo_msg_t *msg, const PSEUDO_STATBUF *buf) {
if (!msg || !buf)
return;
msg->uid = buf->st_uid;
msg->gid = buf->st_gid;
msg->dev = buf->st_dev;
msg->ino = buf->st_ino;
msg->mode = buf->st_mode;
msg->rdev = buf->st_rdev;
msg->nlink = buf->st_nlink;
}
void
pseudo_stat_msg(PSEUDO_STATBUF *buf, const pseudo_msg_t *msg) {
if (!msg || !buf)
return;
buf->st_uid = msg->uid;
buf->st_gid = msg->gid;
buf->st_mode = msg->mode;
buf->st_rdev = msg->rdev;
}