linux/arch/um/os-Linux/file.c
Jeff Dike b4fd310e16 [PATCH] uml: preserve errno in error paths
The poster child for this patch is the third tuntap_user hunk.  When an ioctl
fails, it properly closes the opened file descriptor and returns.  However,
the close resets errno to 0, and the 'return errno' that follows returns 0
rather than the value that ioctl set.  This caused the caller to believe that
the device open succeeded and had opened file descriptor 0, which caused no
end of interesting behavior.

The rest of this patch is a pass through the UML sources looking for places
where errno could be reset before being passed back out.  A common culprit is
printk, which could call write, being called before errno is returned.

In some cases, where the code ends up being much smaller, I just deleted the
printk.

There was another case where a caller of run_helper looked at errno after a
failure, rather than the return value of run_helper, which was the errno value
that it wanted.

Signed-off-by: Jeff Dike <jdike@addtoit.com>
Cc: Paolo Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-17 11:50:00 -07:00

661 lines
12 KiB
C

/*
* Copyright (C) 2002 Jeff Dike (jdike@karaya.com)
* Licensed under the GPL
*/
#include <stdio.h>
#include <unistd.h>
#include <errno.h>
#include <fcntl.h>
#include <signal.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <sys/ioctl.h>
#include <sys/mount.h>
#include <sys/uio.h>
#include "os.h"
#include "user.h"
#include "kern_util.h"
static void copy_stat(struct uml_stat *dst, struct stat64 *src)
{
*dst = ((struct uml_stat) {
.ust_dev = src->st_dev, /* device */
.ust_ino = src->st_ino, /* inode */
.ust_mode = src->st_mode, /* protection */
.ust_nlink = src->st_nlink, /* number of hard links */
.ust_uid = src->st_uid, /* user ID of owner */
.ust_gid = src->st_gid, /* group ID of owner */
.ust_size = src->st_size, /* total size, in bytes */
.ust_blksize = src->st_blksize, /* blocksize for filesys I/O */
.ust_blocks = src->st_blocks, /* number of blocks allocated */
.ust_atime = src->st_atime, /* time of last access */
.ust_mtime = src->st_mtime, /* time of last modification */
.ust_ctime = src->st_ctime, /* time of last change */
});
}
int os_stat_fd(const int fd, struct uml_stat *ubuf)
{
struct stat64 sbuf;
int err;
do {
err = fstat64(fd, &sbuf);
} while((err < 0) && (errno == EINTR)) ;
if(err < 0)
return(-errno);
if(ubuf != NULL)
copy_stat(ubuf, &sbuf);
return(err);
}
int os_stat_file(const char *file_name, struct uml_stat *ubuf)
{
struct stat64 sbuf;
int err;
do {
err = stat64(file_name, &sbuf);
} while((err < 0) && (errno == EINTR)) ;
if(err < 0)
return(-errno);
if(ubuf != NULL)
copy_stat(ubuf, &sbuf);
return(err);
}
int os_access(const char* file, int mode)
{
int amode, err;
amode=(mode&OS_ACC_R_OK ? R_OK : 0) | (mode&OS_ACC_W_OK ? W_OK : 0) |
(mode&OS_ACC_X_OK ? X_OK : 0) | (mode&OS_ACC_F_OK ? F_OK : 0) ;
err = access(file, amode);
if(err < 0)
return(-errno);
return(0);
}
void os_print_error(int error, const char* str)
{
errno = error < 0 ? -error : error;
perror(str);
}
/* FIXME? required only by hostaudio (because it passes ioctls verbatim) */
int os_ioctl_generic(int fd, unsigned int cmd, unsigned long arg)
{
int err;
err = ioctl(fd, cmd, arg);
if(err < 0)
return(-errno);
return(err);
}
int os_window_size(int fd, int *rows, int *cols)
{
struct winsize size;
if(ioctl(fd, TIOCGWINSZ, &size) < 0)
return(-errno);
*rows = size.ws_row;
*cols = size.ws_col;
return(0);
}
int os_new_tty_pgrp(int fd, int pid)
{
if(ioctl(fd, TIOCSCTTY, 0) < 0)
return -errno;
if(tcsetpgrp(fd, pid) < 0)
return -errno;
return(0);
}
/* FIXME: ensure namebuf in os_get_if_name is big enough */
int os_get_ifname(int fd, char* namebuf)
{
if(ioctl(fd, SIOCGIFNAME, namebuf) < 0)
return(-errno);
return(0);
}
int os_set_slip(int fd)
{
int disc, sencap;
disc = N_SLIP;
if(ioctl(fd, TIOCSETD, &disc) < 0)
return -errno;
sencap = 0;
if(ioctl(fd, SIOCSIFENCAP, &sencap) < 0)
return -errno;
return(0);
}
int os_set_owner(int fd, int pid)
{
if(fcntl(fd, F_SETOWN, pid) < 0){
int save_errno = errno;
if(fcntl(fd, F_GETOWN, 0) != pid)
return(-save_errno);
}
return(0);
}
/* FIXME? moved wholesale from sigio_user.c to get fcntls out of that file */
int os_sigio_async(int master, int slave)
{
int flags;
flags = fcntl(master, F_GETFL);
if(flags < 0)
return errno;
if((fcntl(master, F_SETFL, flags | O_NONBLOCK | O_ASYNC) < 0) ||
(fcntl(master, F_SETOWN, os_getpid()) < 0))
return -errno;
if((fcntl(slave, F_SETFL, flags | O_NONBLOCK) < 0))
return -errno;
return(0);
}
int os_mode_fd(int fd, int mode)
{
int err;
do {
err = fchmod(fd, mode);
} while((err < 0) && (errno==EINTR)) ;
if(err < 0)
return(-errno);
return(0);
}
int os_file_type(char *file)
{
struct uml_stat buf;
int err;
err = os_stat_file(file, &buf);
if(err < 0)
return(err);
if(S_ISDIR(buf.ust_mode)) return(OS_TYPE_DIR);
else if(S_ISLNK(buf.ust_mode)) return(OS_TYPE_SYMLINK);
else if(S_ISCHR(buf.ust_mode)) return(OS_TYPE_CHARDEV);
else if(S_ISBLK(buf.ust_mode)) return(OS_TYPE_BLOCKDEV);
else if(S_ISFIFO(buf.ust_mode)) return(OS_TYPE_FIFO);
else if(S_ISSOCK(buf.ust_mode)) return(OS_TYPE_SOCK);
else return(OS_TYPE_FILE);
}
int os_file_mode(char *file, struct openflags *mode_out)
{
int err;
*mode_out = OPENFLAGS();
err = os_access(file, OS_ACC_W_OK);
if((err < 0) && (err != -EACCES))
return(err);
*mode_out = of_write(*mode_out);
err = os_access(file, OS_ACC_R_OK);
if((err < 0) && (err != -EACCES))
return(err);
*mode_out = of_read(*mode_out);
return(0);
}
int os_open_file(char *file, struct openflags flags, int mode)
{
int fd, err, f = 0;
if(flags.r && flags.w) f = O_RDWR;
else if(flags.r) f = O_RDONLY;
else if(flags.w) f = O_WRONLY;
else f = 0;
if(flags.s) f |= O_SYNC;
if(flags.c) f |= O_CREAT;
if(flags.t) f |= O_TRUNC;
if(flags.e) f |= O_EXCL;
fd = open64(file, f, mode);
if(fd < 0)
return(-errno);
if(flags.cl && fcntl(fd, F_SETFD, 1)){
err = -errno;
os_close_file(fd);
return err;
}
return(fd);
}
int os_connect_socket(char *name)
{
struct sockaddr_un sock;
int fd, err;
sock.sun_family = AF_UNIX;
snprintf(sock.sun_path, sizeof(sock.sun_path), "%s", name);
fd = socket(AF_UNIX, SOCK_STREAM, 0);
if(fd < 0)
return(fd);
err = connect(fd, (struct sockaddr *) &sock, sizeof(sock));
if(err)
return(-errno);
return(fd);
}
void os_close_file(int fd)
{
close(fd);
}
int os_seek_file(int fd, __u64 offset)
{
__u64 actual;
actual = lseek64(fd, offset, SEEK_SET);
if(actual != offset)
return(-errno);
return(0);
}
static int fault_buffer(void *start, int len,
int (*copy_proc)(void *addr, void *buf, int len))
{
int page = getpagesize(), i;
char c;
for(i = 0; i < len; i += page){
if((*copy_proc)(start + i, &c, sizeof(c)))
return(-EFAULT);
}
if((len % page) != 0){
if((*copy_proc)(start + len - 1, &c, sizeof(c)))
return(-EFAULT);
}
return(0);
}
static int file_io(int fd, void *buf, int len,
int (*io_proc)(int fd, void *buf, int len),
int (*copy_user_proc)(void *addr, void *buf, int len))
{
int n, err;
do {
n = (*io_proc)(fd, buf, len);
if((n < 0) && (errno == EFAULT)){
err = fault_buffer(buf, len, copy_user_proc);
if(err)
return(err);
n = (*io_proc)(fd, buf, len);
}
} while((n < 0) && (errno == EINTR));
if(n < 0)
return(-errno);
return(n);
}
int os_read_file(int fd, void *buf, int len)
{
return(file_io(fd, buf, len, (int (*)(int, void *, int)) read,
copy_from_user_proc));
}
int os_write_file(int fd, const void *buf, int len)
{
return(file_io(fd, (void *) buf, len,
(int (*)(int, void *, int)) write, copy_to_user_proc));
}
int os_file_size(char *file, unsigned long long *size_out)
{
struct uml_stat buf;
int err;
err = os_stat_file(file, &buf);
if(err < 0){
printk("Couldn't stat \"%s\" : err = %d\n", file, -err);
return(err);
}
if(S_ISBLK(buf.ust_mode)){
int fd, blocks;
fd = os_open_file(file, of_read(OPENFLAGS()), 0);
if(fd < 0){
printk("Couldn't open \"%s\", errno = %d\n", file, -fd);
return(fd);
}
if(ioctl(fd, BLKGETSIZE, &blocks) < 0){
err = -errno;
printk("Couldn't get the block size of \"%s\", "
"errno = %d\n", file, errno);
os_close_file(fd);
return(err);
}
*size_out = ((long long) blocks) * 512;
os_close_file(fd);
return(0);
}
*size_out = buf.ust_size;
return(0);
}
int os_file_modtime(char *file, unsigned long *modtime)
{
struct uml_stat buf;
int err;
err = os_stat_file(file, &buf);
if(err < 0){
printk("Couldn't stat \"%s\" : err = %d\n", file, -err);
return(err);
}
*modtime = buf.ust_mtime;
return(0);
}
int os_get_exec_close(int fd, int* close_on_exec)
{
int ret;
do {
ret = fcntl(fd, F_GETFD);
} while((ret < 0) && (errno == EINTR)) ;
if(ret < 0)
return(-errno);
*close_on_exec = (ret&FD_CLOEXEC) ? 1 : 0;
return(ret);
}
int os_set_exec_close(int fd, int close_on_exec)
{
int flag, err;
if(close_on_exec) flag = FD_CLOEXEC;
else flag = 0;
do {
err = fcntl(fd, F_SETFD, flag);
} while((err < 0) && (errno == EINTR)) ;
if(err < 0)
return(-errno);
return(err);
}
int os_pipe(int *fds, int stream, int close_on_exec)
{
int err, type = stream ? SOCK_STREAM : SOCK_DGRAM;
err = socketpair(AF_UNIX, type, 0, fds);
if(err < 0)
return(-errno);
if(!close_on_exec)
return(0);
err = os_set_exec_close(fds[0], 1);
if(err < 0)
goto error;
err = os_set_exec_close(fds[1], 1);
if(err < 0)
goto error;
return(0);
error:
printk("os_pipe : Setting FD_CLOEXEC failed, err = %d\n", -err);
os_close_file(fds[1]);
os_close_file(fds[0]);
return(err);
}
int os_set_fd_async(int fd, int owner)
{
int err;
/* XXX This should do F_GETFL first */
if(fcntl(fd, F_SETFL, O_ASYNC | O_NONBLOCK) < 0){
err = -errno;
printk("os_set_fd_async : failed to set O_ASYNC and "
"O_NONBLOCK on fd # %d, errno = %d\n", fd, errno);
return err;
}
#ifdef notdef
if(fcntl(fd, F_SETFD, 1) < 0){
printk("os_set_fd_async : Setting FD_CLOEXEC failed, "
"errno = %d\n", errno);
}
#endif
if((fcntl(fd, F_SETSIG, SIGIO) < 0) ||
(fcntl(fd, F_SETOWN, owner) < 0)){
err = -errno;
printk("os_set_fd_async : Failed to fcntl F_SETOWN "
"(or F_SETSIG) fd %d to pid %d, errno = %d\n", fd,
owner, errno);
return err;
}
return(0);
}
int os_clear_fd_async(int fd)
{
int flags = fcntl(fd, F_GETFL);
flags &= ~(O_ASYNC | O_NONBLOCK);
if(fcntl(fd, F_SETFL, flags) < 0)
return(-errno);
return(0);
}
int os_set_fd_block(int fd, int blocking)
{
int flags;
flags = fcntl(fd, F_GETFL);
if(blocking) flags &= ~O_NONBLOCK;
else flags |= O_NONBLOCK;
if(fcntl(fd, F_SETFL, flags) < 0)
return -errno;
return(0);
}
int os_accept_connection(int fd)
{
int new;
new = accept(fd, NULL, 0);
if(new < 0)
return(-errno);
return(new);
}
#ifndef SHUT_RD
#define SHUT_RD 0
#endif
#ifndef SHUT_WR
#define SHUT_WR 1
#endif
#ifndef SHUT_RDWR
#define SHUT_RDWR 2
#endif
int os_shutdown_socket(int fd, int r, int w)
{
int what, err;
if(r && w) what = SHUT_RDWR;
else if(r) what = SHUT_RD;
else if(w) what = SHUT_WR;
else {
printk("os_shutdown_socket : neither r or w was set\n");
return(-EINVAL);
}
err = shutdown(fd, what);
if(err < 0)
return(-errno);
return(0);
}
int os_rcv_fd(int fd, int *helper_pid_out)
{
int new, n;
char buf[CMSG_SPACE(sizeof(new))];
struct msghdr msg;
struct cmsghdr *cmsg;
struct iovec iov;
msg.msg_name = NULL;
msg.msg_namelen = 0;
iov = ((struct iovec) { .iov_base = helper_pid_out,
.iov_len = sizeof(*helper_pid_out) });
msg.msg_iov = &iov;
msg.msg_iovlen = 1;
msg.msg_control = buf;
msg.msg_controllen = sizeof(buf);
msg.msg_flags = 0;
n = recvmsg(fd, &msg, 0);
if(n < 0)
return(-errno);
else if(n != sizeof(iov.iov_len))
*helper_pid_out = -1;
cmsg = CMSG_FIRSTHDR(&msg);
if(cmsg == NULL){
printk("rcv_fd didn't receive anything, error = %d\n", errno);
return(-1);
}
if((cmsg->cmsg_level != SOL_SOCKET) ||
(cmsg->cmsg_type != SCM_RIGHTS)){
printk("rcv_fd didn't receive a descriptor\n");
return(-1);
}
new = ((int *) CMSG_DATA(cmsg))[0];
return(new);
}
int os_create_unix_socket(char *file, int len, int close_on_exec)
{
struct sockaddr_un addr;
int sock, err;
sock = socket(PF_UNIX, SOCK_DGRAM, 0);
if(sock < 0)
return -errno;
if(close_on_exec) {
err = os_set_exec_close(sock, 1);
if(err < 0)
printk("create_unix_socket : close_on_exec failed, "
"err = %d", -err);
}
addr.sun_family = AF_UNIX;
/* XXX Be more careful about overflow */
snprintf(addr.sun_path, len, "%s", file);
err = bind(sock, (struct sockaddr *) &addr, sizeof(addr));
if(err < 0)
return -errno;
return(sock);
}
void os_flush_stdout(void)
{
fflush(stdout);
}
int os_lock_file(int fd, int excl)
{
int type = excl ? F_WRLCK : F_RDLCK;
struct flock lock = ((struct flock) { .l_type = type,
.l_whence = SEEK_SET,
.l_start = 0,
.l_len = 0 } );
int err, save;
err = fcntl(fd, F_SETLK, &lock);
if(!err)
goto out;
save = -errno;
err = fcntl(fd, F_GETLK, &lock);
if(err){
err = -errno;
goto out;
}
printk("F_SETLK failed, file already locked by pid %d\n", lock.l_pid);
err = save;
out:
return(err);
}
/*
* 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:
*/