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minix/servers/vfs/main.c
David van Moolenbroek b423d7b477 Merge of David's ptrace branch. Summary: 
o Support for ptrace T_ATTACH/T_DETACH and T_SYSCALL
o PM signal handling logic should now work properly, even with debuggers
  being present
o Asynchronous PM/VFS protocol, full IPC support for senda(), and
  AMF_NOREPLY senda() flag

DETAILS

Process stop and delay call handling of PM:
o Added sys_runctl() kernel call with sys_stop() and sys_resume()
  aliases, for PM to stop and resume a process
o Added exception for sending/syscall-traced processes to sys_runctl(),
  and matching SIGKREADY pseudo-signal to PM
o Fixed PM signal logic to deal with requests from a process after
  stopping it (so-called "delay calls"), using the SIGKREADY facility
o Fixed various PM panics due to race conditions with delay calls versus
  VFS calls
o Removed special PRIO_STOP priority value
o Added SYS_LOCK RTS kernel flag, to stop an individual process from
  running while modifying its process structure

Signal and debugger handling in PM:
o Fixed debugger signals being dropped if a second signal arrives when
  the debugger has not retrieved the first one
o Fixed debugger signals being sent to the debugger more than once
o Fixed debugger signals unpausing process in VFS; removed PM_UNPAUSE_TR
  protocol message
o Detached debugger signals from general signal logic and from being
  blocked on VFS calls, meaning that even VFS can now be traced
o Fixed debugger being unable to receive more than one pending signal in
  one process stop
o Fixed signal delivery being delayed needlessly when multiple signals
  are pending
o Fixed wait test for tracer, which was returning for children that were
  not waited for
o Removed second parallel pending call from PM to VFS for any process
o Fixed process becoming runnable between exec() and debugger trap
o Added support for notifying the debugger before the parent when a
  debugged child exits
o Fixed debugger death causing child to remain stopped forever
o Fixed consistently incorrect use of _NSIG

Extensions to ptrace():
o Added T_ATTACH and T_DETACH ptrace request, to attach and detach a
  debugger to and from a process
o Added T_SYSCALL ptrace request, to trace system calls
o Added T_SETOPT ptrace request, to set trace options
o Added TO_TRACEFORK trace option, to attach automatically to children
  of a traced process
o Added TO_ALTEXEC trace option, to send SIGSTOP instead of SIGTRAP upon
  a successful exec() of the tracee
o Extended T_GETUSER ptrace support to allow retrieving a process's priv
  structure
o Removed T_STOP ptrace request again, as it does not help implementing
  debuggers properly
o Added MINIX3-specific ptrace test (test42)
o Added proper manual page for ptrace(2)

Asynchronous PM/VFS interface:
o Fixed asynchronous messages not being checked when receive() is called
  with an endpoint other than ANY
o Added AMF_NOREPLY senda() flag, preventing such messages from
  satisfying the receive part of a sendrec()
o Added asynsend3() that takes optional flags; asynsend() is now a
  #define passing in 0 as third parameter
o Made PM/VFS protocol asynchronous; reintroduced tell_fs()
o Made PM_BASE request/reply number range unique
o Hacked in a horrible temporary workaround into RS to deal with newly
  revealed RS-PM-VFS race condition triangle until VFS is asynchronous

System signal handling:
o Fixed shutdown logic of device drivers; removed old SIGKSTOP signal
o Removed is-superuser check from PM's do_procstat() (aka getsigset())
o Added sigset macros to allow system processes to deal with the full
  signal set, rather than just the POSIX subset

Miscellaneous PM fixes:
o Split do_getset into do_get and do_set, merging common code and making
  structure clearer
o Fixed setpriority() being able to put to sleep processes using an
  invalid parameter, or revive zombie processes
o Made find_proc() global; removed obsolete proc_from_pid()
o Cleanup here and there

Also included:
o Fixed false-positive boot order kernel warning
o Removed last traces of old NOTIFY_FROM code

THINGS OF POSSIBLE INTEREST

o It should now be possible to run PM at any priority, even lower than
  user processes
o No assumptions are made about communication speed between PM and VFS,
  although communication must be FIFO
o A debugger will now receive incoming debuggee signals at kill time
  only; the process may not yet be fully stopped
o A first step has been made towards making the SYSTEM task preemptible
2009-09-30 09:57:22 +00:00

600 lines
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/*
* a loop that gets messages requesting work, carries out the work, and sends
* replies.
*
* The entry points into this file are:
* main: main program of the Virtual File System
* reply: send a reply to a process after the requested work is done
*
* Changes for VFS:
* Jul 2006 (Balazs Gerofi)
*/
#include "fs.h"
#include <fcntl.h>
#include <string.h>
#include <stdio.h>
#include <signal.h>
#include <assert.h>
#include <stdlib.h>
#include <sys/ioc_memory.h>
#include <sys/svrctl.h>
#include <sys/select.h>
#include <minix/callnr.h>
#include <minix/com.h>
#include <minix/keymap.h>
#include <minix/const.h>
#include <minix/endpoint.h>
#include <minix/safecopies.h>
#include <minix/debug.h>
#include "file.h"
#include "fproc.h"
#include "param.h"
#include <minix/vfsif.h>
#include "vmnt.h"
#include "vnode.h"
#if ENABLE_SYSCALL_STATS
EXTERN unsigned long calls_stats[NCALLS];
#endif
FORWARD _PROTOTYPE( void fs_init, (void) );
FORWARD _PROTOTYPE( void get_work, (void) );
FORWARD _PROTOTYPE( void init_root, (void) );
FORWARD _PROTOTYPE( void service_pm, (void) );
/*===========================================================================*
* main *
*===========================================================================*/
PUBLIC int main(void)
{
/* This is the main program of the file system. The main loop consists of
* three major activities: getting new work, processing the work, and sending
* the reply. This loop never terminates as long as the file system runs.
*/
int error;
fs_init();
SANITYCHECK;
#if DO_SANITYCHECKS
FIXME("VFS: DO_SANITYCHECKS is on");
#endif
/* This is the main loop that gets work, processes it, and sends replies. */
while (TRUE) {
SANITYCHECK;
get_work(); /* sets who and call_nr */
if (call_nr == DEV_REVIVE)
{
endpoint_t endpt;
endpt = m_in.REP_ENDPT;
if(endpt == FS_PROC_NR) {
endpt = suspended_ep(m_in.m_source, m_in.REP_IO_GRANT);
if(endpt == NONE) {
printf("FS: proc with "
"grant %d from %d not found (revive)\n",
m_in.REP_IO_GRANT, m_in.m_source);
continue;
}
}
revive(endpt, m_in.REP_STATUS);
continue;
}
if (call_nr == DEV_REOPEN_REPL)
{
reopen_reply();
continue;
}
if (call_nr == DEV_CLOSE_REPL)
{
close_reply();
continue;
}
if (call_nr == DEV_SEL_REPL1)
{
select_reply1();
continue;
}
if (call_nr == DEV_SEL_REPL2)
{
select_reply2();
continue;
}
/* Check for special control messages first. */
if (is_notify(call_nr)) {
if (who_p == PM_PROC_NR)
{
/* Signaled by PM, ignore. */
}
else if (who_p == CLOCK)
{
/* Alarm timer expired. Used only for select().
* Check it.
*/
fs_expire_timers(m_in.NOTIFY_TIMESTAMP);
}
else
{
/* Device notifies us of an event. */
dev_status(&m_in);
}
SANITYCHECK;
continue;
}
/* We only expect notify()s from tasks. */
if(who_p < 0) {
printf("FS: ignoring message from %d (%d)\n",
who_e, m_in.m_type);
continue;
}
/* Now it's safe to set and check fp. */
fp = &fproc[who_p]; /* pointer to proc table struct */
super_user = (fp->fp_effuid == SU_UID ? TRUE : FALSE); /* su? */
#if DO_SANITYCHECKS
if(fp_is_blocked(fp)) {
printf("VFS: requester %d call %d: suspended\n",
who_e, call_nr);
panic(__FILE__, "requester suspended", NO_NUM);
}
#endif
/* Calls from PM. */
if (who_e == PM_PROC_NR) {
service_pm();
continue;
}
/* Calls from VM. */
if(who_e == VM_PROC_NR) {
int caught = 1;
switch(call_nr)
{
case VM_VFS_OPEN:
error = do_vm_open();
break;
case VM_VFS_CLOSE:
error = do_vm_close();
break;
case VM_VFS_MMAP:
error = do_vm_mmap();
break;
default:
caught = 0;
break;
}
if(caught) {
reply(who_e, error);
continue;
}
}
SANITYCHECK;
/* Other calls. */
switch(call_nr)
{
case DEVCTL:
error= do_devctl();
if (error != SUSPEND) reply(who_e, error);
break;
case MAPDRIVER:
error= do_mapdriver();
if (error != SUSPEND) reply(who_e, error);
break;
default:
/* Call the internal function that does the work. */
if (call_nr < 0 || call_nr >= NCALLS) {
error = SUSPEND;
/* Not supposed to happen. */
printf("VFS: illegal %d system call by %d\n",
call_nr, who_e);
} else if (fp->fp_pid == PID_FREE) {
error = ENOSYS;
printf(
"FS, bad process, who = %d, call_nr = %d, endpt1 = %d\n",
who_e, call_nr, m_in.endpt1);
} else {
#if ENABLE_SYSCALL_STATS
calls_stats[call_nr]++;
#endif
SANITYCHECK;
error = (*call_vec[call_nr])();
SANITYCHECK;
}
/* Copy the results back to the user and send reply. */
if (error != SUSPEND) { reply(who_e, error); }
}
SANITYCHECK;
}
return(OK); /* shouldn't come here */
}
/*===========================================================================*
* get_work *
*===========================================================================*/
PRIVATE void get_work()
{
/* Normally wait for new input. However, if 'reviving' is
* nonzero, a suspended process must be awakened.
*/
int r, found_one, fd_nr;
struct filp *f;
register struct fproc *rp;
while (reviving != 0) {
found_one= FALSE;
/* Revive a suspended process. */
for (rp = &fproc[0]; rp < &fproc[NR_PROCS]; rp++)
if (rp->fp_pid != PID_FREE && rp->fp_revived == REVIVING) {
int blocked_on = rp->fp_blocked_on;
found_one= TRUE;
who_p = (int)(rp - fproc);
who_e = rp->fp_endpoint;
call_nr = rp->fp_fd & BYTE;
m_in.fd = (rp->fp_fd >>8) & BYTE;
m_in.buffer = rp->fp_buffer;
m_in.nbytes = rp->fp_nbytes;
/*no longer hanging*/
rp->fp_blocked_on = FP_BLOCKED_ON_NONE;
rp->fp_revived = NOT_REVIVING;
reviving--;
/* This should be a pipe I/O, not a device I/O.
* If it is, it'll 'leak' grants.
*/
assert(!GRANT_VALID(rp->fp_grant));
if (blocked_on == FP_BLOCKED_ON_PIPE)
{
fp= rp;
fd_nr= (rp->fp_fd >> 8);
f= get_filp(fd_nr);
assert(f != NULL);
r= rw_pipe((call_nr == READ) ? READING :
WRITING, who_e, fd_nr, f,
rp->fp_buffer, rp->fp_nbytes);
if (r != SUSPEND)
reply(who_e, r);
continue;
}
return;
}
if (!found_one)
panic(__FILE__,"get_work couldn't revive anyone", NO_NUM);
}
for(;;) {
int r;
/* Normal case. No one to revive. */
if ((r=receive(ANY, &m_in)) != OK)
panic(__FILE__,"fs receive error", r);
who_e = m_in.m_source;
who_p = _ENDPOINT_P(who_e);
/*
* negative who_p is never used to access the fproc array. Negative numbers
* (kernel tasks) are treated in a special way
*/
if(who_p >= (int)(sizeof(fproc) / sizeof(struct fproc)))
panic(__FILE__,"receive process out of range", who_p);
if(who_p >= 0 && fproc[who_p].fp_endpoint == NONE) {
printf("FS: ignoring request from %d, endpointless slot %d (%d)\n",
m_in.m_source, who_p, m_in.m_type);
continue;
}
if(who_p >= 0 && fproc[who_p].fp_endpoint != who_e) {
if(fproc[who_p].fp_endpoint == NONE) {
printf("slot unknown even\n");
}
printf("FS: receive endpoint inconsistent (source %d, who_p %d, stored ep %d, who_e %d).\n",
m_in.m_source, who_p, fproc[who_p].fp_endpoint, who_e);
#if 0
panic(__FILE__, "FS: inconsistent endpoint ", NO_NUM);
#endif
continue;
}
call_nr = m_in.m_type;
return;
}
}
/*===========================================================================*
* reply *
*===========================================================================*/
PUBLIC void reply(whom, result)
int whom; /* process to reply to */
int result; /* result of the call (usually OK or error #) */
{
/* Send a reply to a user process. If the send fails, just ignore it. */
int s;
#if 0
if (call_nr == SYMLINK)
printf("vfs:reply: replying %d for call %d\n", result, call_nr);
#endif
m_out.reply_type = result;
s = sendnb(whom, &m_out);
if (s != OK) printf("VFS: couldn't send reply %d to %d: %d\n",
result, whom, s);
}
/*===========================================================================*
* fs_init *
*===========================================================================*/
PRIVATE void fs_init()
{
/* Initialize global variables, tables, etc. */
int s;
register struct fproc *rfp;
struct vmnt *vmp;
struct vnode *root_vp;
message mess;
/* Clear endpoint field */
last_login_fs_e = NONE;
mount_m_in.m1_p3 = (char *) NONE;
/* Initialize the process table with help of the process manager messages.
* Expect one message for each system process with its slot number and pid.
* When no more processes follow, the magic process number NONE is sent.
* Then, stop and synchronize with the PM.
*/
do {
if (OK != (s=receive(PM_PROC_NR, &mess)))
panic(__FILE__,"FS couldn't receive from PM", s);
if (NONE == mess.PR_ENDPT) break;
rfp = &fproc[mess.PR_SLOT];
rfp->fp_pid = mess.PR_PID;
rfp->fp_endpoint = mess.PR_ENDPT;
rfp->fp_realuid = (uid_t) SYS_UID;
rfp->fp_effuid = (uid_t) SYS_UID;
rfp->fp_realgid = (gid_t) SYS_GID;
rfp->fp_effgid = (gid_t) SYS_GID;
rfp->fp_umask = ~0;
rfp->fp_grant = GRANT_INVALID;
rfp->fp_blocked_on = FP_BLOCKED_ON_NONE;
rfp->fp_revived = NOT_REVIVING;
} while (TRUE); /* continue until process NONE */
mess.m_type = OK; /* tell PM that we succeeded */
s = send(PM_PROC_NR, &mess); /* send synchronization message */
/* All process table entries have been set. Continue with FS initialization.
* Certain relations must hold for the file system to work at all. Some
* extra block_size requirements are checked at super-block-read-in time.
*/
if (OPEN_MAX > 127) panic(__FILE__,"OPEN_MAX > 127", NO_NUM);
/* The following initializations are needed to let dev_opcl succeed .*/
fp = (struct fproc *) NULL;
who_e = who_p = FS_PROC_NR;
build_dmap(); /* build device table and map boot driver */
init_root(); /* init root device and load super block */
init_select(); /* init select() structures */
vmp = &vmnt[0]; /* Should be the root filesystem */
if (vmp->m_dev == NO_DEV)
panic(__FILE__, "vfs:fs_init: no root filesystem", NO_NUM);
root_vp= vmp->m_root_node;
/* The root device can now be accessed; set process directories. */
for (rfp=&fproc[0]; rfp < &fproc[NR_PROCS]; rfp++) {
FD_ZERO(&(rfp->fp_filp_inuse));
if (rfp->fp_pid != PID_FREE) {
dup_vnode(root_vp);
rfp->fp_rd = root_vp;
dup_vnode(root_vp);
rfp->fp_wd = root_vp;
} else rfp->fp_endpoint = NONE;
}
system_hz = sys_hz();
}
/*===========================================================================*
* init_root *
*===========================================================================*/
PRIVATE void init_root()
{
int r = OK;
struct vmnt *vmp;
struct vnode *root_node;
struct dmap *dp;
char *label;
message m;
struct node_details resX;
/* Open the root device. */
root_dev = DEV_IMGRD;
ROOT_FS_E = MFS_PROC_NR;
/* Wait FS login message */
if (last_login_fs_e != ROOT_FS_E) {
/* Wait FS login message */
if (receive(ROOT_FS_E, &m) != OK) {
printf("VFS: Error receiving login request from FS_e %d\n",
ROOT_FS_E);
panic(__FILE__, "Error receiving login request from root filesystem\n", ROOT_FS_E);
}
if (m.m_type != FS_READY) {
printf("VFS: Invalid login request from FS_e %d\n",
ROOT_FS_E);
panic(__FILE__, "Error receiving login request from root filesystem\n", ROOT_FS_E);
}
}
last_login_fs_e = NONE;
/* Initialize vmnt table */
for (vmp = &vmnt[0]; vmp < &vmnt[NR_MNTS]; ++vmp)
vmp->m_dev = NO_DEV;
vmp = &vmnt[0];
/* We'll need a vnode for the root inode, check whether there is one */
if ((root_node = get_free_vnode(__FILE__, __LINE__)) == NIL_VNODE) {
panic(__FILE__,"Cannot get free vnode", r);
}
/* Get driver process' endpoint */
dp = &dmap[(root_dev >> MAJOR) & BYTE];
if (dp->dmap_driver == NONE) {
panic(__FILE__,"No driver for root device", r);
}
label= dp->dmap_label;
if (strlen(label) == 0)
{
panic(__FILE__, "vfs:init_root: no label for major", root_dev >> MAJOR);
}
/* Issue request */
r = req_readsuper(ROOT_FS_E, label, root_dev, 0 /*!readonly*/,
1 /*isroot*/, &resX);
if (r != OK) {
panic(__FILE__,"Cannot read superblock from root", r);
}
/* Fill in root node's fields */
root_node->v_fs_e = resX.fs_e;
root_node->v_inode_nr = resX.inode_nr;
root_node->v_mode = resX.fmode;
root_node->v_size = resX.fsize;
root_node->v_sdev = NO_DEV;
root_node->v_fs_count = 1;
root_node->v_ref_count = 1;
/* Fill in max file size and blocksize for the vmnt */
vmp->m_fs_e = resX.fs_e;
vmp->m_dev = root_dev;
vmp->m_flags = 0;
/* Root node is indeed on the partition */
root_node->v_vmnt = vmp;
root_node->v_dev = vmp->m_dev;
/* Root directory is not mounted on a vnode. */
vmp->m_mounted_on = NULL;
vmp->m_root_node = root_node;
}
/*===========================================================================*
* service_pm *
*===========================================================================*/
PRIVATE void service_pm()
{
int r;
switch (call_nr) {
case PM_SETUID:
pm_setuid(m_in.PM_PROC, m_in.PM_EID, m_in.PM_RID);
m_out.m_type = PM_SETUID_REPLY;
m_out.PM_PROC = m_in.PM_PROC;
break;
case PM_SETGID:
pm_setgid(m_in.PM_PROC, m_in.PM_EID, m_in.PM_RID);
m_out.m_type = PM_SETGID_REPLY;
m_out.PM_PROC = m_in.PM_PROC;
break;
case PM_SETSID:
pm_setsid(m_in.PM_PROC);
m_out.m_type = PM_SETSID_REPLY;
m_out.PM_PROC = m_in.PM_PROC;
break;
case PM_EXEC:
r = pm_exec(m_in.PM_PROC, m_in.PM_PATH, m_in.PM_PATH_LEN,
m_in.PM_FRAME, m_in.PM_FRAME_LEN);
/* Reply status to PM */
m_out.m_type = PM_EXEC_REPLY;
m_out.PM_PROC = m_in.PM_PROC;
m_out.PM_STATUS = r;
break;
case PM_EXIT:
pm_exit(m_in.PM_PROC);
/* Reply dummy status to PM for synchronization */
m_out.m_type = PM_EXIT_REPLY;
m_out.PM_PROC = m_in.PM_PROC;
break;
case PM_DUMPCORE:
r = pm_dumpcore(m_in.PM_PROC,
NULL /* (struct mem_map *) m_in.PM_SEGPTR */);
/* Reply status to PM */
m_out.m_type = PM_CORE_REPLY;
m_out.PM_PROC = m_in.PM_PROC;
m_out.PM_STATUS = r;
break;
case PM_FORK:
case PM_FORK_NB:
pm_fork(m_in.PM_PPROC, m_in.PM_PROC, m_in.PM_CPID);
m_out.m_type = (call_nr == PM_FORK) ? PM_FORK_REPLY : PM_FORK_NB_REPLY;
m_out.PM_PROC = m_in.PM_PROC;
break;
case PM_UNPAUSE:
unpause(m_in.PM_PROC);
m_out.m_type = PM_UNPAUSE_REPLY;
m_out.PM_PROC = m_in.PM_PROC;
break;
case PM_REBOOT:
pm_reboot();
/* Reply dummy status to PM for synchronization */
m_out.m_type = PM_REBOOT_REPLY;
break;
default:
printf("VFS: don't know how to handle PM request %x\n", call_nr);
return;
}
r = send(PM_PROC_NR, &m_out);
if (r != OK)
panic(__FILE__, "service_pm: send failed", r);
}
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