#include <stdio.h>
#include <stdlib.h>
#include <stddef.h>
#include <stdarg.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/mman.h>
#include <sys/statfs.h>
#include "kern_util.h"
#include "user.h"
#include "mem_user.h"
#include "init.h"
#include "os.h"
#include "tempfile.h"
#include "kern_constants.h"
#include <sys/param.h>
/* Modified by which_tmpdir, which is called during early boot */
static char *default_tmpdir = "/tmp";
/*
* Modified when creating the physical memory file and when checking
* the tmp filesystem for usability, both happening during early boot.
*/
static char *tempdir = NULL;
static void __init find_tempdir(void)
{
const char *dirs[] = { "TMP", "TEMP", "TMPDIR", NULL };
int i;
char *dir = NULL;
if(tempdir != NULL) /* We've already been called */
return;
for(i = 0; dirs[i]; i++){
dir = getenv(dirs[i]);
if((dir != NULL) && (*dir != '\0'))
break;
}
if((dir == NULL) || (*dir == '\0'))
dir = default_tmpdir;
tempdir = malloc(strlen(dir) + 2);
if(tempdir == NULL){
fprintf(stderr, "Failed to malloc tempdir, "
"errno = %d\n", errno);
return;
}
strcpy(tempdir, dir);
strcat(tempdir, "/");
}
/* This will return 1, with the first character in buf being the
* character following the next instance of c in the file. This will
* read the file as needed. If there's an error, -errno is returned;
* if the end of the file is reached, 0 is returned.
*/
static int next(int fd, char *buf, size_t size, char c)
{
ssize_t n;
size_t len;
char *ptr;
while((ptr = strchr(buf, c)) == NULL){
n = read(fd, buf, size - 1);
if(n == 0)
return 0;
else if(n < 0)
return -errno;
buf[n] = '\0';
}
ptr++;
len = strlen(ptr);
memmove(buf, ptr, len + 1);
/* Refill the buffer so that if there's a partial string that we care
* about, it will be completed, and we can recognize it.
*/
n = read(fd, &buf[len], size - len - 1);
if(n < 0)
return -errno;
buf[len + n] = '\0';
return 1;
}
/* which_tmpdir is called only during early boot */
static int checked_tmpdir = 0;
/* Look for a tmpfs mounted at /dev/shm. I couldn't find a cleaner
* way to do this than to parse /proc/mounts. statfs will return the
* same filesystem magic number and fs id for both /dev and /dev/shm
* when they are both tmpfs, so you can't tell if they are different
* filesystems. Also, there seems to be no other way of finding the
* mount point of a filesystem from within it.
*
* If a /dev/shm tmpfs entry is found, then we switch to using it.
* Otherwise, we stay with the default /tmp.
*/
static void which_tmpdir(void)
{
int fd, found;
char buf[128] = { '\0' };
if(checked_tmpdir)
return;
checked_tmpdir = 1;
printf("Checking for tmpfs mount on /dev/shm...");
fd = open("/proc/mounts", O_RDONLY);
if(fd < 0){
printf("failed to open /proc/mounts, errno = %d\n", errno);
return;
}
while(1){
found = next(fd, buf, ARRAY_SIZE(buf), ' ');
if(found != 1)
break;
if(!strncmp(buf, "/dev/shm", strlen("/dev/shm")))
goto found;
found = next(fd, buf, ARRAY_SIZE(buf), '\n');
if(found != 1)
break;
}
err:
if(found == 0)
printf("nothing mounted on /dev/shm\n");
else if(found < 0)
printf("read returned errno %d\n", -found);
out:
close(fd);
return;
found:
found = next(fd, buf, ARRAY_SIZE(buf), ' ');
if(found != 1)
goto err;
if(strncmp(buf, "tmpfs", strlen("tmpfs"))){
printf("not tmpfs\n");
goto out;
}
printf("OK\n");
default_tmpdir = "/dev/shm";
goto out;
}
/*
* This proc still used in tt-mode
* (file: kernel/tt/ptproxy/proxy.c, proc: start_debugger).
* So it isn't 'static' yet.
*/
int __init make_tempfile(const char *template, char **out_tempname,
int do_unlink)
{
char *tempname;
int fd;
which_tmpdir();
tempname = malloc(MAXPATHLEN);
if (!tempname)
goto out;
find_tempdir();
if (template[0] != '/')
strcpy(tempname, tempdir);
else
tempname[0] = '\0';
strncat(tempname, template, MAXPATHLEN-1-strlen(tempname));
fd = mkstemp(tempname);
if(fd < 0){
fprintf(stderr, "open - cannot create %s: %s\n", tempname,
strerror(errno));
goto out;
}
if(do_unlink && (unlink(tempname) < 0)){
perror("unlink");
goto out;
}
if(out_tempname){
*out_tempname = tempname;
} else {
free(tempname);
}
return fd;
out:
free(tempname);
return -1;
}
#define TEMPNAME_TEMPLATE "vm_file-XXXXXX"
/*
* This proc is used in start_up.c
* So it isn't 'static'.
*/
int __init create_tmp_file(unsigned long long len)
{
int fd, err;
char zero;
fd = make_tempfile(TEMPNAME_TEMPLATE, NULL, 1);
if(fd < 0) {
exit(1);
}
err = fchmod(fd, 0777);
if(err < 0){
perror("fchmod");
exit(1);
}
/* Seek to len - 1 because writing a character there will
* increase the file size by one byte, to the desired length.
*/
if (lseek64(fd, len - 1, SEEK_SET) < 0) {
perror("lseek64");
exit(1);
}
zero = 0;
err = write(fd, &zero, 1);
if(err != 1){
perror("write");
exit(1);
}
return fd;
}
int __init create_mem_file(unsigned long long len)
{
int err, fd;
fd = create_tmp_file(len);
err = os_set_exec_close(fd);
if(err < 0){
errno = -err;
perror("exec_close");
}
return fd;
}
void __init check_tmpexec(void)
{
void *addr;
int err, fd = create_tmp_file(UM_KERN_PAGE_SIZE);
addr = mmap(NULL, UM_KERN_PAGE_SIZE,
PROT_READ | PROT_WRITE | PROT_EXEC, MAP_PRIVATE, fd, 0);
printf("Checking PROT_EXEC mmap in %s...",tempdir);
fflush(stdout);
if(addr == MAP_FAILED){
err = errno;
perror("failed");
close(fd);
if(err == EPERM)
printf("%s must be not mounted noexec\n",tempdir);
exit(1);
}
printf("OK\n");
munmap(addr, UM_KERN_PAGE_SIZE);
close(fd);
}
