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
Riku Voipio
parent
38a762fec6
commit
e36800c91a
@ -60,6 +60,7 @@ int __clone2(int (*fn)(void *), void *child_stack_base,
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#include <sys/statfs.h>
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#include <utime.h>
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#include <sys/sysinfo.h>
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#include <sys/signalfd.h>
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//#include <sys/user.h>
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#include <netinet/ip.h>
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#include <netinet/tcp.h>
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@ -294,6 +295,54 @@ static bitmask_transtbl fcntl_flags_tbl[] = {
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{ 0, 0, 0, 0 }
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};
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typedef abi_long (*TargetFdFunc)(void *, size_t);
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typedef struct TargetFdTrans {
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TargetFdFunc host_to_target;
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TargetFdFunc target_to_host;
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} TargetFdTrans;
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static TargetFdTrans **target_fd_trans;
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static unsigned int target_fd_max;
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static TargetFdFunc fd_trans_host_to_target(int fd)
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{
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if (fd < target_fd_max && target_fd_trans[fd]) {
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return target_fd_trans[fd]->host_to_target;
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}
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return NULL;
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}
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static void fd_trans_register(int fd, TargetFdTrans *trans)
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{
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unsigned int oldmax;
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if (fd >= target_fd_max) {
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oldmax = target_fd_max;
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target_fd_max = ((fd >> 6) + 1) << 6; /* by slice of 64 entries */
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target_fd_trans = g_realloc(target_fd_trans,
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target_fd_max * sizeof(TargetFdTrans));
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memset((void *)(target_fd_trans + oldmax), 0,
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(target_fd_max - oldmax) * sizeof(TargetFdTrans *));
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}
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target_fd_trans[fd] = trans;
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}
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static void fd_trans_unregister(int fd)
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{
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if (fd >= 0 && fd < target_fd_max) {
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target_fd_trans[fd] = NULL;
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}
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}
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static void fd_trans_dup(int oldfd, int newfd)
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{
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fd_trans_unregister(newfd);
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if (oldfd < target_fd_max && target_fd_trans[oldfd]) {
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fd_trans_register(newfd, target_fd_trans[oldfd]);
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}
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}
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static int sys_getcwd1(char *buf, size_t size)
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{
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if (getcwd(buf, size) == NULL) {
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@ -5340,6 +5389,92 @@ static abi_long do_open_by_handle_at(abi_long mount_fd, abi_long handle,
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}
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#endif
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#if defined(TARGET_NR_signalfd) || defined(TARGET_NR_signalfd4)
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/* signalfd siginfo conversion */
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static void
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host_to_target_signalfd_siginfo(struct signalfd_siginfo *tinfo,
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const struct signalfd_siginfo *info)
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{
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int sig = host_to_target_signal(info->ssi_signo);
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/* linux/signalfd.h defines a ssi_addr_lsb
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* not defined in sys/signalfd.h but used by some kernels
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*/
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#ifdef BUS_MCEERR_AO
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if (tinfo->ssi_signo == SIGBUS &&
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(tinfo->ssi_code == BUS_MCEERR_AR ||
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tinfo->ssi_code == BUS_MCEERR_AO)) {
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uint16_t *ssi_addr_lsb = (uint16_t *)(&info->ssi_addr + 1);
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uint16_t *tssi_addr_lsb = (uint16_t *)(&tinfo->ssi_addr + 1);
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*tssi_addr_lsb = tswap16(*ssi_addr_lsb);
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}
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#endif
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tinfo->ssi_signo = tswap32(sig);
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tinfo->ssi_errno = tswap32(tinfo->ssi_errno);
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tinfo->ssi_code = tswap32(info->ssi_code);
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tinfo->ssi_pid = tswap32(info->ssi_pid);
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tinfo->ssi_uid = tswap32(info->ssi_uid);
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tinfo->ssi_fd = tswap32(info->ssi_fd);
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tinfo->ssi_tid = tswap32(info->ssi_tid);
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tinfo->ssi_band = tswap32(info->ssi_band);
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tinfo->ssi_overrun = tswap32(info->ssi_overrun);
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tinfo->ssi_trapno = tswap32(info->ssi_trapno);
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tinfo->ssi_status = tswap32(info->ssi_status);
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tinfo->ssi_int = tswap32(info->ssi_int);
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tinfo->ssi_ptr = tswap64(info->ssi_ptr);
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tinfo->ssi_utime = tswap64(info->ssi_utime);
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tinfo->ssi_stime = tswap64(info->ssi_stime);
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tinfo->ssi_addr = tswap64(info->ssi_addr);
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}
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static abi_long host_to_target_signalfd(void *buf, size_t len)
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{
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int i;
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for (i = 0; i < len; i += sizeof(struct signalfd_siginfo)) {
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host_to_target_signalfd_siginfo(buf + i, buf + i);
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}
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return len;
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}
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static TargetFdTrans target_signalfd_trans = {
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.host_to_target = host_to_target_signalfd,
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};
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static abi_long do_signalfd4(int fd, abi_long mask, int flags)
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{
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int host_flags;
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target_sigset_t *target_mask;
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sigset_t host_mask;
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abi_long ret;
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if (flags & ~(TARGET_O_NONBLOCK | TARGET_O_CLOEXEC)) {
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return -TARGET_EINVAL;
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}
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if (!lock_user_struct(VERIFY_READ, target_mask, mask, 1)) {
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return -TARGET_EFAULT;
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}
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target_to_host_sigset(&host_mask, target_mask);
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host_flags = target_to_host_bitmask(flags, fcntl_flags_tbl);
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ret = get_errno(signalfd(fd, &host_mask, host_flags));
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if (ret >= 0) {
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fd_trans_register(ret, &target_signalfd_trans);
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}
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unlock_user_struct(target_mask, mask, 0);
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return ret;
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}
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#endif
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/* Map host to target signal numbers for the wait family of syscalls.
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Assume all other status bits are the same. */
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int host_to_target_waitstatus(int status)
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@ -5724,6 +5859,10 @@ abi_long do_syscall(void *cpu_env, int num, abi_long arg1,
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if (!(p = lock_user(VERIFY_WRITE, arg2, arg3, 0)))
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goto efault;
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ret = get_errno(read(arg1, p, arg3));
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if (ret >= 0 &&
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fd_trans_host_to_target(arg1)) {
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ret = fd_trans_host_to_target(arg1)(p, ret);
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}
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unlock_user(p, arg2, ret);
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}
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break;
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@ -5740,6 +5879,7 @@ abi_long do_syscall(void *cpu_env, int num, abi_long arg1,
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ret = get_errno(do_openat(cpu_env, AT_FDCWD, p,
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target_to_host_bitmask(arg2, fcntl_flags_tbl),
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arg3));
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fd_trans_unregister(ret);
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unlock_user(p, arg1, 0);
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break;
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#endif
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@ -5749,6 +5889,7 @@ abi_long do_syscall(void *cpu_env, int num, abi_long arg1,
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ret = get_errno(do_openat(cpu_env, arg1, p,
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target_to_host_bitmask(arg3, fcntl_flags_tbl),
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arg4));
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fd_trans_unregister(ret);
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unlock_user(p, arg2, 0);
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break;
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#if defined(TARGET_NR_name_to_handle_at) && defined(CONFIG_OPEN_BY_HANDLE)
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@ -5759,9 +5900,11 @@ abi_long do_syscall(void *cpu_env, int num, abi_long arg1,
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#if defined(TARGET_NR_open_by_handle_at) && defined(CONFIG_OPEN_BY_HANDLE)
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case TARGET_NR_open_by_handle_at:
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ret = do_open_by_handle_at(arg1, arg2, arg3);
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fd_trans_unregister(ret);
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break;
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#endif
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case TARGET_NR_close:
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fd_trans_unregister(arg1);
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ret = get_errno(close(arg1));
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break;
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case TARGET_NR_brk:
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@ -5803,6 +5946,7 @@ abi_long do_syscall(void *cpu_env, int num, abi_long arg1,
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if (!(p = lock_user_string(arg1)))
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goto efault;
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ret = get_errno(creat(p, arg2));
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fd_trans_unregister(ret);
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unlock_user(p, arg1, 0);
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break;
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#endif
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@ -6250,6 +6394,9 @@ abi_long do_syscall(void *cpu_env, int num, abi_long arg1,
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#endif
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case TARGET_NR_dup:
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ret = get_errno(dup(arg1));
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if (ret >= 0) {
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fd_trans_dup(arg1, ret);
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}
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break;
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#ifdef TARGET_NR_pipe
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case TARGET_NR_pipe:
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@ -6347,11 +6494,17 @@ abi_long do_syscall(void *cpu_env, int num, abi_long arg1,
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#ifdef TARGET_NR_dup2
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case TARGET_NR_dup2:
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ret = get_errno(dup2(arg1, arg2));
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if (ret >= 0) {
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fd_trans_dup(arg1, arg2);
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}
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break;
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#endif
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#if defined(CONFIG_DUP3) && defined(TARGET_NR_dup3)
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case TARGET_NR_dup3:
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ret = get_errno(dup3(arg1, arg2, arg3));
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if (ret >= 0) {
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fd_trans_dup(arg1, arg2);
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}
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break;
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#endif
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#ifdef TARGET_NR_getppid /* not on alpha */
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@ -7347,6 +7500,7 @@ abi_long do_syscall(void *cpu_env, int num, abi_long arg1,
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#ifdef TARGET_NR_socket
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case TARGET_NR_socket:
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ret = do_socket(arg1, arg2, arg3);
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fd_trans_unregister(ret);
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break;
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#endif
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#ifdef TARGET_NR_socketpair
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@ -9600,6 +9754,7 @@ abi_long do_syscall(void *cpu_env, int num, abi_long arg1,
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#if defined(TARGET_NR_eventfd)
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case TARGET_NR_eventfd:
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ret = get_errno(eventfd(arg1, 0));
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fd_trans_unregister(ret);
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break;
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#endif
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#if defined(TARGET_NR_eventfd2)
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@ -9613,6 +9768,7 @@ abi_long do_syscall(void *cpu_env, int num, abi_long arg1,
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host_flags |= O_CLOEXEC;
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}
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ret = get_errno(eventfd(arg1, host_flags));
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fd_trans_unregister(ret);
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break;
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}
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#endif
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@ -9655,6 +9811,16 @@ abi_long do_syscall(void *cpu_env, int num, abi_long arg1,
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break;
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#endif
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#endif
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#if defined(TARGET_NR_signalfd4)
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case TARGET_NR_signalfd4:
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ret = do_signalfd4(arg1, arg2, arg4);
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break;
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#endif
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#if defined(TARGET_NR_signalfd)
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case TARGET_NR_signalfd:
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ret = do_signalfd4(arg1, arg2, 0);
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break;
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#endif
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#if defined(CONFIG_EPOLL)
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#if defined(TARGET_NR_epoll_create)
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case TARGET_NR_epoll_create:
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@ -9926,6 +10092,7 @@ abi_long do_syscall(void *cpu_env, int num, abi_long arg1,
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timer_t htimer = g_posix_timers[timerid];
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ret = get_errno(timer_getoverrun(htimer));
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}
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fd_trans_unregister(ret);
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break;
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}
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#endif
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