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linux/arch/um/kernel/user_util.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

170 lines
3.9 KiB
C

/*
* Copyright (C) 2000, 2001, 2002 Jeff Dike (jdike@karaya.com)
* Licensed under the GPL
*/
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <limits.h>
#include <setjmp.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <sys/utsname.h>
#include <sys/param.h>
#include <sys/time.h>
#include "asm/types.h"
#include <ctype.h>
#include <signal.h>
#include <wait.h>
#include <errno.h>
#include <stdarg.h>
#include <sched.h>
#include <termios.h>
#include <string.h>
#include "user_util.h"
#include "kern_util.h"
#include "user.h"
#include "mem_user.h"
#include "init.h"
#include "helper.h"
#include "ptrace_user.h"
#include "uml-config.h"
void stop(void)
{
while(1) sleep(1000000);
}
void stack_protections(unsigned long address)
{
int prot = PROT_READ | PROT_WRITE | PROT_EXEC;
if(mprotect((void *) address, page_size(), prot) < 0)
panic("protecting stack failed, errno = %d", errno);
}
void task_protections(unsigned long address)
{
unsigned long guard = address + page_size();
unsigned long stack = guard + page_size();
int prot = 0, pages;
#ifdef notdef
if(mprotect((void *) stack, page_size(), prot) < 0)
panic("protecting guard page failed, errno = %d", errno);
#endif
pages = (1 << UML_CONFIG_KERNEL_STACK_ORDER) - 2;
prot = PROT_READ | PROT_WRITE | PROT_EXEC;
if(mprotect((void *) stack, pages * page_size(), prot) < 0)
panic("protecting stack failed, errno = %d", errno);
}
int wait_for_stop(int pid, int sig, int cont_type, void *relay)
{
sigset_t *relay_signals = relay;
int status, ret;
while(1){
CATCH_EINTR(ret = waitpid(pid, &status, WUNTRACED));
if((ret < 0) ||
!WIFSTOPPED(status) || (WSTOPSIG(status) != sig)){
if(ret < 0){
printk("wait failed, errno = %d\n",
errno);
}
else if(WIFEXITED(status))
printk("process %d exited with status %d\n",
pid, WEXITSTATUS(status));
else if(WIFSIGNALED(status))
printk("process %d exited with signal %d\n",
pid, WTERMSIG(status));
else if((WSTOPSIG(status) == SIGVTALRM) ||
(WSTOPSIG(status) == SIGALRM) ||
(WSTOPSIG(status) == SIGIO) ||
(WSTOPSIG(status) == SIGPROF) ||
(WSTOPSIG(status) == SIGCHLD) ||
(WSTOPSIG(status) == SIGWINCH) ||
(WSTOPSIG(status) == SIGINT)){
ptrace(cont_type, pid, 0, WSTOPSIG(status));
continue;
}
else if((relay_signals != NULL) &&
sigismember(relay_signals, WSTOPSIG(status))){
ptrace(cont_type, pid, 0, WSTOPSIG(status));
continue;
}
else printk("process %d stopped with signal %d\n",
pid, WSTOPSIG(status));
panic("wait_for_stop failed to wait for %d to stop "
"with %d\n", pid, sig);
}
return(status);
}
}
int raw(int fd)
{
struct termios tt;
int err;
CATCH_EINTR(err = tcgetattr(fd, &tt));
if(err < 0)
return -errno;
cfmakeraw(&tt);
CATCH_EINTR(err = tcsetattr(fd, TCSADRAIN, &tt));
if(err < 0)
return -errno;
/* XXX tcsetattr could have applied only some changes
* (and cfmakeraw() is a set of changes) */
return(0);
}
void setup_machinename(char *machine_out)
{
struct utsname host;
uname(&host);
strcpy(machine_out, host.machine);
}
char host_info[(_UTSNAME_LENGTH + 1) * 4 + _UTSNAME_NODENAME_LENGTH + 1];
void setup_hostinfo(void)
{
struct utsname host;
uname(&host);
sprintf(host_info, "%s %s %s %s %s", host.sysname, host.nodename,
host.release, host.version, host.machine);
}
int setjmp_wrapper(void (*proc)(void *, void *), ...)
{
va_list args;
sigjmp_buf buf;
int n;
n = sigsetjmp(buf, 1);
if(n == 0){
va_start(args, proc);
(*proc)(&buf, &args);
}
va_end(args);
return(n);
}
/*
* 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:
*/