132 lines
3.5 KiB
C
132 lines
3.5 KiB
C
/* This file handles nested counter-request calls to VFS sent by file system
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* (FS) servers in response to VFS requests.
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*
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* The entry points into this file are
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* nested_fs_call perform a nested call from a file system server
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* nested_dev_call perform a nested call from a device driver server
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*
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*/
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#include "fs.h"
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#include "fproc.h"
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#include <string.h>
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#include <assert.h>
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#include <minix/callnr.h>
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#include <minix/endpoint.h>
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#include <minix/vfsif.h>
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/* maximum nested call stack depth */
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#define MAX_DEPTH 1
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/* global variables stack */
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PRIVATE struct {
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struct fproc *g_fp; /* pointer to caller process */
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message g_m_in; /* request message */
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message g_m_out; /* reply message */
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int g_who_e; /* endpoint of caller process */
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int g_who_p; /* slot number of caller process */
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int g_call_nr; /* call number */
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int g_super_user; /* is the caller root? */
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char g_user_fullpath[PATH_MAX]; /* path to look up */
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} globals[MAX_DEPTH];
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PRIVATE int depth = 0; /* current globals stack level */
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FORWARD _PROTOTYPE( int push_globals, (void) );
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FORWARD _PROTOTYPE( void pop_globals, (void) );
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FORWARD _PROTOTYPE( void set_globals, (message *m) );
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/*===========================================================================*
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* push_globals *
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*===========================================================================*/
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PRIVATE int push_globals()
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{
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/* Save the global variables of the current call onto the globals stack.
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*/
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if (depth == MAX_DEPTH)
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return(EPERM);
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globals[depth].g_fp = fp;
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globals[depth].g_m_in = m_in;
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globals[depth].g_m_out = m_out;
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globals[depth].g_super_user = super_user;
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/* err_code is not used across blocking calls */
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depth++;
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return(OK);
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}
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/*===========================================================================*
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* pop_globals *
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*===========================================================================*/
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PRIVATE void pop_globals()
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{
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/* Restore the global variables of a call from the globals stack.
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*/
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if (depth == 0)
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panic("Popping from empty globals stack!");
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depth--;
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fp = globals[depth].g_fp;
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m_in = globals[depth].g_m_in;
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m_out = globals[depth].g_m_out;
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}
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/*===========================================================================*
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* set_globals *
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*===========================================================================*/
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PRIVATE void set_globals(m)
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message *m; /* request message */
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{
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/* Initialize global variables based on a request message.
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*/
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int proc_p;
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m_in = *m;
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proc_p = _ENDPOINT_P(m_in.m_source);
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fp = &fproc[proc_p];
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/* the rest need not be initialized */
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}
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/*===========================================================================*
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* nested_fs_call *
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*===========================================================================*/
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PUBLIC void nested_fs_call(m)
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message *m; /* request/reply message pointer */
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{
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/* Handle a nested call from a file system server.
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*/
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int r;
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/* Save global variables of the current call */
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if ((r = push_globals()) != OK) {
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printf("VFS: error saving global variables in call %d from FS %d\n",
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m->m_type, m->m_source);
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} else {
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/* Initialize global variables for the nested call */
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set_globals(m);
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/* Perform the nested call - only getsysinfo() is allowed right now */
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if (call_nr == COMMON_GETSYSINFO) {
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r = do_getsysinfo();
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} else {
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printf("VFS: invalid nested call %d from FS %d\n", call_nr,
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who_e);
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r = ENOSYS;
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}
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/* Store the result, and restore original global variables */
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*m = m_out;
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pop_globals();
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}
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m->m_type = r;
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}
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