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linux-user: add signalfd/signalfd4 syscalls 

This patch introduces a system very similar to the one used in the kernel
to attach specific functions to a given file descriptor.

In this case, we attach a specific "host_to_target()" translator to the fd
returned by signalfd() to be able to byte-swap the signalfd_siginfo
structure provided by read().

This patch allows to execute the example program given by
man signalfd(2):

 #include <sys/signalfd.h>
 #include <signal.h>
 #include <unistd.h>
 #include <stdlib.h>
 #include <stdio.h>

 #define handle_error(msg) \
     do { perror(msg); exit(EXIT_FAILURE); } while (0)

 int
 main(int argc, char *argv[])
 {
     sigset_t mask;
     int sfd;
     struct signalfd_siginfo fdsi;
     ssize_t s;

     sigemptyset(&mask);
     sigaddset(&mask, SIGINT);
     sigaddset(&mask, SIGQUIT);

     /* Block signals so that they aren't handled
        according to their default dispositions */

     if (sigprocmask(SIG_BLOCK, &mask, NULL) == -1)
         handle_error("sigprocmask");

     sfd = signalfd(-1, &mask, 0);
     if (sfd == -1)
         handle_error("signalfd");

     for (;;) {
         s = read(sfd, &fdsi, sizeof(struct signalfd_siginfo));
         if (s != sizeof(struct signalfd_siginfo))
             handle_error("read");

         if (fdsi.ssi_signo == SIGINT) {
             printf("Got SIGINT\n");
         } else if (fdsi.ssi_signo == SIGQUIT) {
             printf("Got SIGQUIT\n");
             exit(EXIT_SUCCESS);
         } else {
             printf("Read unexpected signal\n");
         }
     }
 }

 $ ./signalfd_demo
 ^CGot SIGINT
 ^CGot SIGINT
 ^\Got SIGQUIT

Signed-off-by: Laurent Vivier <laurent@vivier.eu>
Signed-off-by: Riku Voipio <riku.voipio@linaro.org>
This commit is contained in:
Laurent Vivier 2015-10-02 14:48:09 +02:00 committed by Riku Voipio
parent 38a762fec6
commit e36800c91a
1 changed files with 167 additions and 0 deletions
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167
linux-user/syscall.c
View File

@ -60,6 +60,7 @@ int __clone2(int (*fn)(void *), void *child_stack_base,
#include <sys/statfs.h>
#include <utime.h>
#include <sys/sysinfo.h>
#include <sys/signalfd.h>
//#include <sys/user.h>
#include <netinet/ip.h>
#include <netinet/tcp.h>
@ -294,6 +295,54 @@ static bitmask_transtbl fcntl_flags_tbl[] = {
{ 0, 0, 0, 0 }
};
typedef abi_long (*TargetFdFunc)(void *, size_t);
typedef struct TargetFdTrans {
TargetFdFunc host_to_target;
TargetFdFunc target_to_host;
} TargetFdTrans;
static TargetFdTrans **target_fd_trans;
static unsigned int target_fd_max;
static TargetFdFunc fd_trans_host_to_target(int fd)
{
if (fd < target_fd_max && target_fd_trans[fd]) {
return target_fd_trans[fd]->host_to_target;
}
return NULL;
}
static void fd_trans_register(int fd, TargetFdTrans *trans)
{
unsigned int oldmax;
if (fd >= target_fd_max) {
oldmax = target_fd_max;
target_fd_max = ((fd >> 6) + 1) << 6; /* by slice of 64 entries */
target_fd_trans = g_realloc(target_fd_trans,
target_fd_max * sizeof(TargetFdTrans));
memset((void *)(target_fd_trans + oldmax), 0,
(target_fd_max - oldmax) * sizeof(TargetFdTrans *));
}
target_fd_trans[fd] = trans;
}
static void fd_trans_unregister(int fd)
{
if (fd >= 0 && fd < target_fd_max) {
target_fd_trans[fd] = NULL;
}
}
static void fd_trans_dup(int oldfd, int newfd)
{
fd_trans_unregister(newfd);
if (oldfd < target_fd_max && target_fd_trans[oldfd]) {
fd_trans_register(newfd, target_fd_trans[oldfd]);
}
}
static int sys_getcwd1(char *buf, size_t size)
{
if (getcwd(buf, size) == NULL) {
@ -5340,6 +5389,92 @@ static abi_long do_open_by_handle_at(abi_long mount_fd, abi_long handle,
}
#endif
#if defined(TARGET_NR_signalfd) || defined(TARGET_NR_signalfd4)
/* signalfd siginfo conversion */
static void
host_to_target_signalfd_siginfo(struct signalfd_siginfo *tinfo,
const struct signalfd_siginfo *info)
{
int sig = host_to_target_signal(info->ssi_signo);
/* linux/signalfd.h defines a ssi_addr_lsb
* not defined in sys/signalfd.h but used by some kernels
*/
#ifdef BUS_MCEERR_AO
if (tinfo->ssi_signo == SIGBUS &&
(tinfo->ssi_code == BUS_MCEERR_AR ||
tinfo->ssi_code == BUS_MCEERR_AO)) {
uint16_t *ssi_addr_lsb = (uint16_t *)(&info->ssi_addr + 1);
uint16_t *tssi_addr_lsb = (uint16_t *)(&tinfo->ssi_addr + 1);
*tssi_addr_lsb = tswap16(*ssi_addr_lsb);
}
#endif
tinfo->ssi_signo = tswap32(sig);
tinfo->ssi_errno = tswap32(tinfo->ssi_errno);
tinfo->ssi_code = tswap32(info->ssi_code);
tinfo->ssi_pid = tswap32(info->ssi_pid);
tinfo->ssi_uid = tswap32(info->ssi_uid);
tinfo->ssi_fd = tswap32(info->ssi_fd);
tinfo->ssi_tid = tswap32(info->ssi_tid);
tinfo->ssi_band = tswap32(info->ssi_band);
tinfo->ssi_overrun = tswap32(info->ssi_overrun);
tinfo->ssi_trapno = tswap32(info->ssi_trapno);
tinfo->ssi_status = tswap32(info->ssi_status);
tinfo->ssi_int = tswap32(info->ssi_int);
tinfo->ssi_ptr = tswap64(info->ssi_ptr);
tinfo->ssi_utime = tswap64(info->ssi_utime);
tinfo->ssi_stime = tswap64(info->ssi_stime);
tinfo->ssi_addr = tswap64(info->ssi_addr);
}
static abi_long host_to_target_signalfd(void *buf, size_t len)
{
int i;
for (i = 0; i < len; i += sizeof(struct signalfd_siginfo)) {
host_to_target_signalfd_siginfo(buf + i, buf + i);
}
return len;
}
static TargetFdTrans target_signalfd_trans = {
.host_to_target = host_to_target_signalfd,
};
static abi_long do_signalfd4(int fd, abi_long mask, int flags)
{
int host_flags;
target_sigset_t *target_mask;
sigset_t host_mask;
abi_long ret;
if (flags & ~(TARGET_O_NONBLOCK | TARGET_O_CLOEXEC)) {
return -TARGET_EINVAL;
}
if (!lock_user_struct(VERIFY_READ, target_mask, mask, 1)) {
return -TARGET_EFAULT;
}
target_to_host_sigset(&host_mask, target_mask);
host_flags = target_to_host_bitmask(flags, fcntl_flags_tbl);
ret = get_errno(signalfd(fd, &host_mask, host_flags));
if (ret >= 0) {
fd_trans_register(ret, &target_signalfd_trans);
}
unlock_user_struct(target_mask, mask, 0);
return ret;
}
#endif
/* Map host to target signal numbers for the wait family of syscalls.
Assume all other status bits are the same. */
int host_to_target_waitstatus(int status)
@ -5724,6 +5859,10 @@ abi_long do_syscall(void *cpu_env, int num, abi_long arg1,
if (!(p = lock_user(VERIFY_WRITE, arg2, arg3, 0)))
goto efault;
ret = get_errno(read(arg1, p, arg3));
if (ret >= 0 &&
fd_trans_host_to_target(arg1)) {
ret = fd_trans_host_to_target(arg1)(p, ret);
}
unlock_user(p, arg2, ret);
}
break;
@ -5740,6 +5879,7 @@ abi_long do_syscall(void *cpu_env, int num, abi_long arg1,
ret = get_errno(do_openat(cpu_env, AT_FDCWD, p,
target_to_host_bitmask(arg2, fcntl_flags_tbl),
arg3));
fd_trans_unregister(ret);
unlock_user(p, arg1, 0);
break;
#endif
@ -5749,6 +5889,7 @@ abi_long do_syscall(void *cpu_env, int num, abi_long arg1,
ret = get_errno(do_openat(cpu_env, arg1, p,
target_to_host_bitmask(arg3, fcntl_flags_tbl),
arg4));
fd_trans_unregister(ret);
unlock_user(p, arg2, 0);
break;
#if defined(TARGET_NR_name_to_handle_at) && defined(CONFIG_OPEN_BY_HANDLE)
@ -5759,9 +5900,11 @@ abi_long do_syscall(void *cpu_env, int num, abi_long arg1,
#if defined(TARGET_NR_open_by_handle_at) && defined(CONFIG_OPEN_BY_HANDLE)
case TARGET_NR_open_by_handle_at:
ret = do_open_by_handle_at(arg1, arg2, arg3);
fd_trans_unregister(ret);
break;
#endif
case TARGET_NR_close:
fd_trans_unregister(arg1);
ret = get_errno(close(arg1));
break;
case TARGET_NR_brk:
@ -5803,6 +5946,7 @@ abi_long do_syscall(void *cpu_env, int num, abi_long arg1,
if (!(p = lock_user_string(arg1)))
goto efault;
ret = get_errno(creat(p, arg2));
fd_trans_unregister(ret);
unlock_user(p, arg1, 0);
break;
#endif
@ -6250,6 +6394,9 @@ abi_long do_syscall(void *cpu_env, int num, abi_long arg1,
#endif
case TARGET_NR_dup:
ret = get_errno(dup(arg1));
if (ret >= 0) {
fd_trans_dup(arg1, ret);
}
break;
#ifdef TARGET_NR_pipe
case TARGET_NR_pipe:
@ -6347,11 +6494,17 @@ abi_long do_syscall(void *cpu_env, int num, abi_long arg1,
#ifdef TARGET_NR_dup2
case TARGET_NR_dup2:
ret = get_errno(dup2(arg1, arg2));
if (ret >= 0) {
fd_trans_dup(arg1, arg2);
}
break;
#endif
#if defined(CONFIG_DUP3) && defined(TARGET_NR_dup3)
case TARGET_NR_dup3:
ret = get_errno(dup3(arg1, arg2, arg3));
if (ret >= 0) {
fd_trans_dup(arg1, arg2);
}
break;
#endif
#ifdef TARGET_NR_getppid /* not on alpha */
@ -7347,6 +7500,7 @@ abi_long do_syscall(void *cpu_env, int num, abi_long arg1,
#ifdef TARGET_NR_socket
case TARGET_NR_socket:
ret = do_socket(arg1, arg2, arg3);
fd_trans_unregister(ret);
break;
#endif
#ifdef TARGET_NR_socketpair
@ -9600,6 +9754,7 @@ abi_long do_syscall(void *cpu_env, int num, abi_long arg1,
#if defined(TARGET_NR_eventfd)
case TARGET_NR_eventfd:
ret = get_errno(eventfd(arg1, 0));
fd_trans_unregister(ret);
break;
#endif
#if defined(TARGET_NR_eventfd2)
@ -9613,6 +9768,7 @@ abi_long do_syscall(void *cpu_env, int num, abi_long arg1,
host_flags |= O_CLOEXEC;
}
ret = get_errno(eventfd(arg1, host_flags));
fd_trans_unregister(ret);
break;
}
#endif
@ -9655,6 +9811,16 @@ abi_long do_syscall(void *cpu_env, int num, abi_long arg1,
break;
#endif
#endif
#if defined(TARGET_NR_signalfd4)
case TARGET_NR_signalfd4:
ret = do_signalfd4(arg1, arg2, arg4);
break;
#endif
#if defined(TARGET_NR_signalfd)
case TARGET_NR_signalfd:
ret = do_signalfd4(arg1, arg2, 0);
break;
#endif
#if defined(CONFIG_EPOLL)
#if defined(TARGET_NR_epoll_create)
case TARGET_NR_epoll_create:
@ -9926,6 +10092,7 @@ abi_long do_syscall(void *cpu_env, int num, abi_long arg1,
timer_t htimer = g_posix_timers[timerid];
ret = get_errno(timer_getoverrun(htimer));
}
fd_trans_unregister(ret);
break;
}
#endif