89c9de7d09
This library provides new abstractions for the upper (VFS) side of
file system services, and should be used for all file system service
implementations from now on. It provides the following functionality:
- a function call table abstraction, hiding the details of the
VFS-FS protocol with simple parameters;
- a (currently limited) number of per-function steps required for
all file system implementations, such as copying in and out path
names and result buffers;
- a default implementation for multicomponent path lookups, such
that the file system merely has to implement resolution of single
components at a time;
- an abstraction for copying data from and to the file system, which
allows transparent intraprocess copying as required for the lookup
implementation;
- a set of functions to simplify getdents implementations.
The message loop provided by the library is currently for use by
single-threaded file system implementations only. Multithreaded file
system services may use the more low-level message processing
functionality.
Protocol-level optimizations such as including names in protocol
messages may be hidden entirely in this library. In addition, in the
future, the lookup implementation may be replaced by a single-
component lookup VFS/FS protocol request as part of a VFS name cache
implementation; this, too, can be hidden entirely in this library.
Change-Id: Ib34f0d0e021dfa3426ce8826efcf3eaa94d3ef3e
97 lines
2.1 KiB
C
97 lines
2.1 KiB
C
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#include "fsdriver.h"
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/* Library-local variables. */
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ino_t fsdriver_root;
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int fsdriver_mounted = FALSE;
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static int fsdriver_running;
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/*
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* Process an incoming VFS request, and send a reply. If the message is not
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* a file system request from VFS, pass it on to the generic message handler.
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* Multithreaded file systems should indicate that the reply is to be sent to
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* VFS asynchronously.
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*/
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void
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fsdriver_process(const struct fsdriver * __restrict fdp,
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const message * __restrict m_ptr, int ipc_status, int asyn_reply)
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{
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message m_out;
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unsigned int call_nr;
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int r, transid;
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/* Is this a file system request at all? */
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if (is_ipc_notify(ipc_status) || m_ptr->m_source != VFS_PROC_NR) {
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if (fdp->fdr_other != NULL)
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fdp->fdr_other(m_ptr, ipc_status);
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return; /* do not send a reply */
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}
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/* Call the appropriate function. */
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transid = TRNS_GET_ID(m_ptr->m_type);
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call_nr = TRNS_DEL_ID(m_ptr->m_type);
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memset(&m_out, 0, sizeof(m_out));
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if (fsdriver_mounted || call_nr == REQ_READSUPER) {
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call_nr -= FS_BASE; /* unsigned; wrapping is intended */
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if (call_nr < NREQS && fsdriver_callvec[call_nr] != NULL)
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r = (fsdriver_callvec[call_nr])(fdp, m_ptr, &m_out);
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else
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r = ENOSYS;
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} else
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r = EINVAL;
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/* Send a reply. */
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m_out.m_type = TRNS_ADD_ID(r, transid);
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if (asyn_reply)
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r = asynsend(m_ptr->m_source, &m_out);
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else
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r = ipc_send(m_ptr->m_source, &m_out);
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if (r != OK)
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printf("fsdriver: sending reply failed (%d)\n", r);
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if (fdp->fdr_postcall != NULL)
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fdp->fdr_postcall();
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}
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/*
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* Terminate the file server as soon as the file system has been unmounted.
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*/
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void
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fsdriver_terminate(void)
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{
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fsdriver_running = FALSE;
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sef_cancel();
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}
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/*
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* Main program of any file server task.
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*/
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void
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fsdriver_task(struct fsdriver * fdp)
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{
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message mess;
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int r, ipc_status;
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fsdriver_running = TRUE;
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while (fsdriver_running || fsdriver_mounted) {
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if ((r = sef_receive_status(ANY, &mess, &ipc_status)) != OK) {
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if (r == EINTR)
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continue; /* sef_cancel() was called */
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panic("fsdriver: sef_receive_status failed: %d", r);
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}
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fsdriver_process(fdp, &mess, ipc_status, FALSE /*asyn_reply*/);
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}
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}
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