linux/arch/um/kernel/umid.c

/* 
 * Copyright (C) 2001, 2002 Jeff Dike (jdike@karaya.com)
 * Licensed under the GPL
 */

#include <stdio.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <stdlib.h>
#include <dirent.h>
#include <signal.h>
#include <sys/stat.h>
#include <sys/param.h>
#include "user.h"
#include "umid.h"
#include "init.h"
#include "os.h"
#include "user_util.h"
#include "choose-mode.h"

#define UMID_LEN 64
#define UML_DIR "~/.uml/"

/* Changed by set_umid and make_umid, which are run early in boot */
static char umid[UMID_LEN] = { 0 };

/* Changed by set_uml_dir and make_uml_dir, which are run early in boot */
static char *uml_dir = UML_DIR;

/* Changed by set_umid */
static int umid_is_random = 1;
static int umid_inited = 0;

static int make_umid(int (*printer)(const char *fmt, ...));

static int __init set_umid(char *name, int is_random,
			   int (*printer)(const char *fmt, ...))
{
	if(umid_inited){
		(*printer)("Unique machine name can't be set twice\n");
		return(-1);
	}

	if(strlen(name) > UMID_LEN - 1)
		(*printer)("Unique machine name is being truncated to %d "
			   "characters\n", UMID_LEN);
	strlcpy(umid, name, sizeof(umid));

	umid_is_random = is_random;
	umid_inited = 1;
	return 0;
}

static int __init set_umid_arg(char *name, int *add)
{
	*add = 0;
	return(set_umid(name, 0, printf));
}

__uml_setup("umid=", set_umid_arg,
"umid=<name>\n"
"    This is used to assign a unique identity to this UML machine and\n"
"    is used for naming the pid file and management console socket.\n\n"
);

int __init umid_file_name(char *name, char *buf, int len)
{
	int n;

	if(!umid_inited && make_umid(printk)) return(-1);

	n = strlen(uml_dir) + strlen(umid) + strlen(name) + 1;
	if(n > len){
		printk("umid_file_name : buffer too short\n");
		return(-1);
	}

	sprintf(buf, "%s%s/%s", uml_dir, umid, name);
	return(0);
}

extern int tracing_pid;

static int __init create_pid_file(void)
{
	char file[strlen(uml_dir) + UMID_LEN + sizeof("/pid\0")];
	char pid[sizeof("nnnnn\0")];
	int fd, n;

	if(umid_file_name("pid", file, sizeof(file))) return 0;

	fd = os_open_file(file, of_create(of_excl(of_rdwr(OPENFLAGS()))), 
			  0644);
	if(fd < 0){
		printf("Open of machine pid file \"%s\" failed: %s\n",
		       file, strerror(-fd));
		return 0;
	}

	sprintf(pid, "%d\n", os_getpid());
	n = os_write_file(fd, pid, strlen(pid));
	if(n != strlen(pid))
		printf("Write of pid file failed - err = %d\n", -n);
	os_close_file(fd);
	return 0;
}

static int actually_do_remove(char *dir)
{
	DIR *directory;
	struct dirent *ent;
	int len;
	char file[256];

	directory = opendir(dir);
	if(directory == NULL){
		printk("actually_do_remove : couldn't open directory '%s', "
		       "errno = %d\n", dir, errno);
		return(1);
	}
	while((ent = readdir(directory)) != NULL){
		if(!strcmp(ent->d_name, ".") || !strcmp(ent->d_name, ".."))
			continue;
		len = strlen(dir) + sizeof("/") + strlen(ent->d_name) + 1;
		if(len > sizeof(file)){
			printk("Not deleting '%s' from '%s' - name too long\n",
			       ent->d_name, dir);
			continue;
		}
		sprintf(file, "%s/%s", dir, ent->d_name);
		if(unlink(file) < 0){
			printk("actually_do_remove : couldn't remove '%s' "
			       "from '%s', errno = %d\n", ent->d_name, dir, 
			       errno);
			return(1);
		}
	}
	if(rmdir(dir) < 0){
		printk("actually_do_remove : couldn't rmdir '%s', "
		       "errno = %d\n", dir, errno);
		return(1);
	}
	return(0);
}

void remove_umid_dir(void)
{
	char dir[strlen(uml_dir) + UMID_LEN + 1];
	if(!umid_inited) return;

	sprintf(dir, "%s%s", uml_dir, umid);
	actually_do_remove(dir);
}

char *get_umid(int only_if_set)
{
	if(only_if_set && umid_is_random) return(NULL);
	return(umid);
}

int not_dead_yet(char *dir)
{
	char file[strlen(uml_dir) + UMID_LEN + sizeof("/pid\0")];
	char pid[sizeof("nnnnn\0")], *end;
	int dead, fd, p, n;

	sprintf(file, "%s/pid", dir);
	dead = 0;
	fd = os_open_file(file, of_read(OPENFLAGS()), 0);
	if(fd < 0){
		if(fd != -ENOENT){
			printk("not_dead_yet : couldn't open pid file '%s', "
			       "err = %d\n", file, -fd);
			return(1);
		}
		dead = 1;
	}
	if(fd > 0){
		n = os_read_file(fd, pid, sizeof(pid));
		if(n < 0){
			printk("not_dead_yet : couldn't read pid file '%s', "
			       "err = %d\n", file, -n);
			return(1);
		}
		p = strtoul(pid, &end, 0);
		if(end == pid){
			printk("not_dead_yet : couldn't parse pid file '%s', "
			       "errno = %d\n", file, errno);
			dead = 1;
		}
		if(((kill(p, 0) < 0) && (errno == ESRCH)) ||
		   (p == CHOOSE_MODE(tracing_pid, os_getpid())))
			dead = 1;
	}
	if(!dead) return(1);
	return(actually_do_remove(dir));
}

static int __init set_uml_dir(char *name, int *add)
{
	if((strlen(name) > 0) && (name[strlen(name) - 1] != '/')){
		uml_dir = malloc(strlen(name) + 2);
		if(uml_dir == NULL){
			printf("Failed to malloc uml_dir - error = %d\n",
			       errno);
			uml_dir = name;
			/* Return 0 here because do_initcalls doesn't look at
			 * the return value.
			 */
			return(0);
		}
		sprintf(uml_dir, "%s/", name);
	}
	else uml_dir = name;
	return(0);
}

static int __init make_uml_dir(void)
{
	char dir[MAXPATHLEN + 1] = { '\0' };
	int len;

	if(*uml_dir == '~'){
		char *home = getenv("HOME");

		if(home == NULL){
			printf("make_uml_dir : no value in environment for "
			       "$HOME\n");
			exit(1);
		}
		strlcpy(dir, home, sizeof(dir));
		uml_dir++;
	}
	len = strlen(dir);
	strncat(dir, uml_dir, sizeof(dir) - len);
	len = strlen(dir);
	if((len > 0) && (len < sizeof(dir) - 1) && (dir[len - 1] != '/')){
		dir[len] = '/';
		dir[len + 1] = '\0';
	}

	uml_dir = malloc(strlen(dir) + 1);
	if(uml_dir == NULL){
		printf("make_uml_dir : malloc failed, errno = %d\n", errno);
		exit(1);
	}
	strcpy(uml_dir, dir);
	
	if((mkdir(uml_dir, 0777) < 0) && (errno != EEXIST)){
	        printf("Failed to mkdir %s: %s\n", uml_dir, strerror(errno));
		return(-1);
	}
	return 0;
}

static int __init make_umid(int (*printer)(const char *fmt, ...))
{
	int fd, err;
	char tmp[strlen(uml_dir) + UMID_LEN + 1];

	strlcpy(tmp, uml_dir, sizeof(tmp));

	if(!umid_inited){
		strcat(tmp, "XXXXXX");
		fd = mkstemp(tmp);
		if(fd < 0){
			(*printer)("make_umid - mkstemp(%s) failed: %s\n",
				   tmp,strerror(errno));
			return(1);
		}

		os_close_file(fd);
		/* There's a nice tiny little race between this unlink and
		 * the mkdir below.  It'd be nice if there were a mkstemp
		 * for directories.
		 */
		unlink(tmp);
		set_umid(&tmp[strlen(uml_dir)], 1, printer);
	}
	
	sprintf(tmp, "%s%s", uml_dir, umid);

	err = mkdir(tmp, 0777);
	if(err < 0){
		if(errno == EEXIST){
			if(not_dead_yet(tmp)){
				(*printer)("umid '%s' is in use\n", umid);
				return(-1);
			}
			err = mkdir(tmp, 0777);
		}
	}
	if(err < 0){
		(*printer)("Failed to create %s - errno = %d\n", umid, errno);
		return(-1);
	}

	return(0);
}

__uml_setup("uml_dir=", set_uml_dir,
"uml_dir=<directory>\n"
"    The location to place the pid and umid files.\n\n"
);

static int __init make_umid_setup(void)
{
	/* one function with the ordering we need ... */
	make_uml_dir();
	make_umid(printf);
	return create_pid_file();
}
__uml_postsetup(make_umid_setup);

/*
 * Overrides for Emacs so that we follow Linus's tabbing style.
 * Emacs will notice this stuff at the end of the file and automatically
 * adjust the settings for this buffer only.  This must remain at the end
 * of the file.
 * ---------------------------------------------------------------------------
 * Local variables:
 * c-file-style: "linux"
 * End:
 */