kernel-ark/arch/um/os-Linux/mem.c
Jeff Dike a61f334fd2 uml: convert libc layer to call read and write
This patch converts calls in the os layer to os_{read,write}_file to calls
directly to libc read() and write() where it is clear that the I/O buffer is
in the kernel.

We can do that here instead of calling os_{read,write}_file_k since we are in
libc code and can call libc directly.

With the change in the calls, error handling needs to be changed to refer to
errno directly rather than the return value of the call.

CATCH_EINTR wrappers were also added where needed.

Signed-off-by: Jeff Dike <jdike@linux.intel.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-05-07 12:13:03 -07:00

280 lines
5.5 KiB
C

#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)
{
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, int size, char c)
{
int n, 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);
find_tempdir();
if (template[0] != '/')
strcpy(tempname, tempdir);
else
tempname[0] = '\0';
strcat(tempname, template);
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("os_mode_fd");
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("os_seek_file");
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, 1);
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");
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);
}