arch/um/os-Linux/helper.c

   1 /*
   2  * Copyright (C) 2002 Jeff Dike (jdike@karaya.com)
   3  * Licensed under the GPL
   4  */
   5
   6 #include <stdio.h>
   7 #include <stdlib.h>
   8 #include <unistd.h>
   9 #include <errno.h>
  10 #include <sched.h>
  11 #include <sys/signal.h>
  12 #include <sys/wait.h>
  13 #include "user.h"
  14 #include "kern_util.h"
  15 #include "user_util.h"
  16 #include "os.h"
  17
  18 struct helper_data {
  19         void (*pre_exec)(void*);
  20         void *pre_data;
  21         char **argv;
  22         int fd;
  23 };
  24
  25 /* Debugging aid, changed only from gdb */
  26 int helper_pause = 0;
  27
  28 static void helper_hup(int sig)
  29 {
  30 }
  31
  32 static int helper_child(void *arg)
  33 {
  34         struct helper_data *data = arg;
  35         char **argv = data->argv;
  36         int errval;
  37
  38         if(helper_pause){
  39                 signal(SIGHUP, helper_hup);
  40                 pause();
  41         }
  42         if(data->pre_exec != NULL)
  43                 (*data->pre_exec)(data->pre_data);
  44         execvp(argv[0], argv);
  45         errval = errno;
  46         printk("execvp of '%s' failed - errno = %d\n", argv[0], errno);
  47         os_write_file(data->fd, &errval, sizeof(errval));
  48         kill(os_getpid(), SIGKILL);
  49         return(0);
  50 }
  51
  52 /* Returns either the pid of the child process we run or -E* on failure.
  53  * XXX The alloc_stack here breaks if this is called in the tracing thread */
  54 int run_helper(void (*pre_exec)(void *), void *pre_data, char **argv,
  55                unsigned long *stack_out)
  56 {
  57         struct helper_data data;
  58         unsigned long stack, sp;
  59         int pid, fds[2], ret, n;
  60
  61         if((stack_out != NULL) && (*stack_out != 0))
  62                 stack = *stack_out;
  63         else stack = alloc_stack(0, um_in_interrupt());
  64         if(stack == 0)
  65                 return(-ENOMEM);
  66
  67         ret = os_pipe(fds, 1, 0);
  68         if(ret < 0){
  69                 printk("run_helper : pipe failed, ret = %d\n", -ret);
  70                 goto out_free;
  71         }
  72
  73         ret = os_set_exec_close(fds[1], 1);
  74         if(ret < 0){
  75                 printk("run_helper : setting FD_CLOEXEC failed, ret = %d\n",
  76                        -ret);
  77                 goto out_close;
  78         }
  79
  80         sp = stack + page_size() - sizeof(void *);
  81         data.pre_exec = pre_exec;
  82         data.pre_data = pre_data;
  83         data.argv = argv;
  84         data.fd = fds[1];
  85         pid = clone(helper_child, (void *) sp, CLONE_VM | SIGCHLD, &data);
  86         if(pid < 0){
  87                 ret = -errno;
  88                 printk("run_helper : clone failed, errno = %d\n", errno);
  89                 goto out_close;
  90         }
  91
  92         close(fds[1]);
  93         fds[1] = -1;
  94
  95         /*Read the errno value from the child.*/
  96         n = os_read_file(fds[0], &ret, sizeof(ret));
  97         if(n < 0){
  98                 printk("run_helper : read on pipe failed, ret = %d\n", -n);
  99                 ret = n;
 100                 kill(pid, SIGKILL);
 101                 CATCH_EINTR(waitpid(pid, NULL, 0));
 102         }
 103         else if(n != 0){
 104                 CATCH_EINTR(n = waitpid(pid, NULL, 0));
 105                 ret = -errno;
 106         } else {
 107                 ret = pid;
 108         }
 109
 110 out_close:
 111         if (fds[1] != -1)
 112                 close(fds[1]);
 113         close(fds[0]);
 114 out_free:
 115         if(stack_out == NULL)
 116                 free_stack(stack, 0);
 117         else *stack_out = stack;
 118         return(ret);
 119 }
 120
 121 int run_helper_thread(int (*proc)(void *), void *arg, unsigned int flags,
 122                       unsigned long *stack_out, int stack_order)
 123 {
 124         unsigned long stack, sp;
 125         int pid, status, err;
 126
 127         stack = alloc_stack(stack_order, um_in_interrupt());
 128         if(stack == 0) return(-ENOMEM);
 129
 130         sp = stack + (page_size() << stack_order) - sizeof(void *);
 131         pid = clone(proc, (void *) sp, flags | SIGCHLD, arg);
 132         if(pid < 0){
 133                 err = -errno;
 134                 printk("run_helper_thread : clone failed, errno = %d\n",
 135                        errno);
 136                 return err;
 137         }
 138         if(stack_out == NULL){
 139                 CATCH_EINTR(pid = waitpid(pid, &status, 0));
 140                 if(pid < 0){
 141                         err = -errno;
 142                         printk("run_helper_thread - wait failed, errno = %d\n",
 143                                errno);
 144                         pid = err;
 145                 }
 146                 if(!WIFEXITED(status) || (WEXITSTATUS(status) != 0))
 147                         printk("run_helper_thread - thread returned status "
 148                                "0x%x\n", status);
 149                 free_stack(stack, stack_order);
 150         }
 151         else *stack_out = stack;
 152         return(pid);
 153 }
 154
 155 int helper_wait(int pid)
 156 {
 157         int ret;
 158
 159         CATCH_EINTR(ret = waitpid(pid, NULL, WNOHANG));
 160         if(ret < 0){
 161                 ret = -errno;
 162                 printk("helper_wait : waitpid failed, errno = %d\n", errno);
 163         }
 164         return(ret);
 165 }