minix/servers/pm/utility.c
Jorrit Herder 322ec9ef8b Moved stime, time, times POSIX calls from FS to PM. Removed child time
accounting from kernel (now in PM).  Large amount of files in this commit
is due to system time problems during development.
2005-05-31 09:50:51 +00:00

179 lines
5.8 KiB
C

/* This file contains some utility routines for PM.
*
* The entry points are:
* get_free_pid: get a free process or group id
* allowed: see if an access is permitted
* no_sys: called for invalid system call numbers
* panic: PM has run aground of a fatal error
* tell_fs: interface to FS
* get_mem_map: get memory map of given process
* get_stack_ptr: get stack pointer of given process
*/
#include "pm.h"
#include <sys/stat.h>
#include <minix/callnr.h>
#include <minix/com.h>
#include <fcntl.h>
#include <signal.h> /* needed only because mproc.h needs it */
#include "mproc.h"
#include "param.h"
#include <minix/config.h>
#include <timers.h>
#include <string.h>
#include "../../kernel/const.h"
#include "../../kernel/type.h"
#include "../../kernel/proc.h"
/*===========================================================================*
* get_free_pid *
*===========================================================================*/
PUBLIC pid_t get_free_pid()
{
static pid_t next_pid = INIT_PID + 1; /* next pid to be assigned */
register struct mproc *rmp; /* check process table */
int t; /* zero if pid still free */
/* Find a free pid for the child and put it in the table. */
do {
t = 0;
next_pid = (next_pid < 30000 ? next_pid + 1 : INIT_PID + 1);
for (rmp = &mproc[0]; rmp < &mproc[NR_PROCS]; rmp++)
if (rmp->mp_pid == next_pid || rmp->mp_procgrp == next_pid) {
t = 1;
break;
}
} while (t); /* 't' = 0 means pid free */
return(next_pid);
}
/*===========================================================================*
* allowed *
*===========================================================================*/
PUBLIC int allowed(name_buf, s_buf, mask)
char *name_buf; /* pointer to file name to be EXECed */
struct stat *s_buf; /* buffer for doing and returning stat struct*/
int mask; /* R_BIT, W_BIT, or X_BIT */
{
/* Check to see if file can be accessed. Return EACCES or ENOENT if the access
* is prohibited. If it is legal open the file and return a file descriptor.
*/
int fd;
int save_errno;
/* Use the fact that mask for access() is the same as the permissions mask.
* E.g., X_BIT in <minix/const.h> is the same as X_OK in <unistd.h> and
* S_IXOTH in <sys/stat.h>. tell_fs(DO_CHDIR, ...) has set PM's real ids
* to the user's effective ids, so access() works right for setuid programs.
*/
if (access(name_buf, mask) < 0) return(-errno);
/* The file is accessible but might not be readable. Make it readable. */
tell_fs(SETUID, PM_PROC_NR, (int) SUPER_USER, (int) SUPER_USER);
/* Open the file and fstat it. Restore the ids early to handle errors. */
fd = open(name_buf, O_RDONLY | O_NONBLOCK);
save_errno = errno; /* open might fail, e.g. from ENFILE */
tell_fs(SETUID, PM_PROC_NR, (int) mp->mp_effuid, (int) mp->mp_effuid);
if (fd < 0) return(-save_errno);
if (fstat(fd, s_buf) < 0) panic("allowed: fstat failed", NO_NUM);
/* Only regular files can be executed. */
if (mask == X_BIT && (s_buf->st_mode & I_TYPE) != I_REGULAR) {
close(fd);
return(EACCES);
}
return(fd);
}
/*===========================================================================*
* no_sys *
*===========================================================================*/
PUBLIC int no_sys()
{
/* A system call number not implemented by PM has been requested. */
return(EINVAL);
}
/*===========================================================================*
* panic *
*===========================================================================*/
PUBLIC void panic(format, num)
char *format; /* format string */
int num; /* number to go with format string */
{
/* An unrecoverable error has occurred. Panics are caused when an internal
* inconsistency is detected, e.g., a programming error or illegal value of a
* defined constant. The process manager decides to shut down. This results
* in a HARD_STOP notification to all system processes to allow local cleanup.
*/
printf("Process manager panic: %s", format);
if (num != NO_NUM) printf(": %d",num);
printf("\n");
sys_abort(RBT_PANIC);
}
/*===========================================================================*
* tell_fs *
*===========================================================================*/
PUBLIC void tell_fs(what, p1, p2, p3)
int what, p1, p2, p3;
{
/* This routine is only used by PM to inform FS of certain events:
* tell_fs(CHDIR, slot, dir, 0)
* tell_fs(EXEC, proc, 0, 0)
* tell_fs(EXIT, proc, 0, 0)
* tell_fs(FORK, parent, child, pid)
* tell_fs(SETGID, proc, realgid, effgid)
* tell_fs(SETSID, proc, 0, 0)
* tell_fs(SETUID, proc, realuid, effuid)
* tell_fs(UNPAUSE, proc, signr, 0)
* tell_fs(STIME, time, 0, 0)
*/
message m;
m.tell_fs_arg1 = p1;
m.tell_fs_arg2 = p2;
m.tell_fs_arg3 = p3;
_taskcall(FS_PROC_NR, what, &m);
}
/*===========================================================================*
* get_mem_map *
*===========================================================================*/
PUBLIC int get_mem_map(proc_nr, mem_map)
int proc_nr; /* process to get map of */
struct mem_map *mem_map; /* put memory map here */
{
struct proc p;
int s;
if ((s=sys_getproc(&p, proc_nr)) != OK)
return(s);
memcpy(mem_map, p.p_memmap, sizeof(p.p_memmap));
return(OK);
}
/*===========================================================================*
* get_stack_ptr *
*===========================================================================*/
PUBLIC int get_stack_ptr(proc_nr, sp)
int proc_nr; /* process to get sp of */
vir_bytes *sp; /* put stack pointer here */
{
struct proc p;
int s;
if ((s=sys_getproc(&p, proc_nr)) != OK)
return(s);
*sp = p.p_reg.sp;
return(OK);
}