diff options
Diffstat (limited to 'sysdeps/mach/hurd/getrandom.c')
| -rw-r--r-- | sysdeps/mach/hurd/getrandom.c | 117 |
1 files changed, 102 insertions, 15 deletions
diff --git a/sysdeps/mach/hurd/getrandom.c b/sysdeps/mach/hurd/getrandom.c index ad2d3ba387..9ee3ef74fb 100644 --- a/sysdeps/mach/hurd/getrandom.c +++ b/sysdeps/mach/hurd/getrandom.c @@ -16,10 +16,13 @@ License along with the GNU C Library; if not, see <https://www.gnu.org/licenses/>. */ +#include <hurd.h> #include <sys/random.h> #include <fcntl.h> -#include <unistd.h> -#include <not-cancel.h> + +__libc_rwlock_define_initialized (static, lock); +static file_t random_server, random_server_nonblock, + urandom_server, urandom_server_nonblock; extern char *__trivfs_server_name __attribute__((weak)); @@ -29,9 +32,36 @@ ssize_t __getrandom (void *buffer, size_t length, unsigned int flags) { const char *random_source = "/dev/urandom"; - int open_flags = O_RDONLY | O_CLOEXEC; - size_t amount_read; - int fd; + int open_flags = O_RDONLY; + file_t server, *cached_server; + error_t err; + char *data = buffer; + mach_msg_type_number_t nread = length; + + switch (flags) + { + case 0: + cached_server = &urandom_server; + break; + case GRND_RANDOM: + cached_server = &random_server; + break; + case GRND_NONBLOCK: + cached_server = &urandom_server_nonblock; + break; + case GRND_RANDOM | GRND_NONBLOCK: + cached_server = &random_server_nonblock; + break; + default: + return __hurd_fail (EINVAL); + } + + if (flags & GRND_RANDOM) + random_source = "/dev/random"; + if (flags & GRND_NONBLOCK) + open_flags |= O_NONBLOCK; + /* No point in passing either O_NOCTTY, O_IGNORE_CTTY, or O_CLOEXEC + to file_name_lookup, since we're not making an fd. */ if (&__trivfs_server_name && __trivfs_server_name && __trivfs_server_name[0] == 'r' @@ -44,19 +74,76 @@ __getrandom (void *buffer, size_t length, unsigned int flags) /* We are random, don't try to read ourselves! */ return length; - if (flags & GRND_RANDOM) - random_source = "/dev/random"; +again: + __libc_rwlock_rdlock (lock); + server = *cached_server; + if (MACH_PORT_VALID (server)) + /* Attempt to read some random data using this port. */ + err = __io_read (server, &data, &nread, -1, length); + else + err = MACH_SEND_INVALID_DEST; + __libc_rwlock_unlock (lock); - if (flags & GRND_NONBLOCK) - open_flags |= O_NONBLOCK; + if (err == MACH_SEND_INVALID_DEST || err == MIG_SERVER_DIED) + { + file_t oldserver = server; + mach_port_urefs_t urefs; + + /* Slow path: the cached port didn't work, or there was no + cached port in the first place. */ + + __libc_rwlock_wrlock (lock); + server = *cached_server; + if (server != oldserver) + { + /* Someone else must have refetched the port while we were + waiting for the lock. */ + __libc_rwlock_unlock (lock); + goto again; + } + + if (MACH_PORT_VALID (server)) + { + /* It could be that someone else has refetched the port and + it got the very same name. So check whether it is a send + right (and not a dead name). */ + err = __mach_port_get_refs (__mach_task_self (), server, + MACH_PORT_RIGHT_SEND, &urefs); + if (!err && urefs > 0) + { + __libc_rwlock_unlock (lock); + goto again; + } + + /* Now we're sure that it's dead. */ + __mach_port_deallocate (__mach_task_self (), server); + } + + server = *cached_server = __file_name_lookup (random_source, + open_flags, 0); + __libc_rwlock_unlock (lock); + if (!MACH_PORT_VALID (server)) + /* No luck. */ + return -1; + + goto again; + } + + if (err) + return __hurd_fail (err); - fd = __open_nocancel(random_source, open_flags); - if (fd == -1) - return -1; + if (data != buffer) + { + if (nread > length) + { + __vm_deallocate (__mach_task_self (), (vm_address_t) data, nread); + return __hurd_fail (EGRATUITOUS); + } + memcpy (buffer, data, nread); + __vm_deallocate (__mach_task_self (), (vm_address_t) data, nread); + } - amount_read = __read_nocancel(fd, buffer, length); - __close_nocancel_nostatus(fd); - return amount_read; + return nread; } libc_hidden_def (__getrandom) |