shared: add random-util.[ch]

Signed-off-by: Anthony G. Basile <blueness@gentoo.org>

6 files changed, 181 insertions, 106 deletions

diff --git a/src/shared/Makefile.am b/src/shared/Makefile.am
index 9f2df41e70..b0b4f59a6c 100644
--- a/src/shared/Makefile.am
+++ b/src/shared/Makefile.am
@@ -20,6 +20,7 @@ libudev_shared_la_SOURCES=\
 	MurmurHash2.c \
 	path-util.c \
 	process-util.c \
+	random-util.c \
 	selinux-util.c \
 	siphash24.c \
 	smack-util.c \
@@ -53,6 +54,7 @@ noinst_HEADERS = \
 	MurmurHash2.h \
 	path-util.h \
 	process-util.h \
+	random-util.h \
 	selinux-util.h \
 	set.h \
 	siphash24.h \
diff --git a/src/shared/hashmap.c b/src/shared/hashmap.c
index 084743e4fb..49bccacb5c 100644
--- a/src/shared/hashmap.c
+++ b/src/shared/hashmap.c
@@ -33,6 +33,7 @@
 #include "strv.h"
 #include "list.h"
 #include "mempool.h"
+#include "random-util.h"
 
 /*
  * Implementation of hashmaps.
diff --git a/src/shared/random-util.c b/src/shared/random-util.c
new file mode 100644
index 0000000000..88f5182508
--- /dev/null
+++ b/src/shared/random-util.c
@@ -0,0 +1,127 @@
+/***
+  This file is part of systemd.
+
+  Copyright 2010 Lennart Poettering
+
+  systemd is free software; you can redistribute it and/or modify it
+  under the terms of the GNU Lesser General Public License as published by
+  the Free Software Foundation; either version 2.1 of the License, or
+  (at your option) any later version.
+
+  systemd is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public License
+  along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+#include <stdint.h>
+#include <errno.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <time.h>
+#include <sys/auxv.h>
+#include <linux/random.h>
+
+#include "random-util.h"
+#include "time-util.h"
+#include "missing.h"
+#include "util.h"
+
+int dev_urandom(void *p, size_t n) {
+        static int have_syscall = -1;
+
+        _cleanup_close_ int fd = -1;
+        int r;
+
+        /* Gathers some randomness from the kernel. This call will
+         * never block, and will always return some data from the
+         * kernel, regardless if the random pool is fully initialized
+         * or not. It thus makes no guarantee for the quality of the
+         * returned entropy, but is good enough for or usual usecases
+         * of seeding the hash functions for hashtable */
+
+        /* Use the getrandom() syscall unless we know we don't have
+         * it, or when the requested size is too large for it. */
+        if (have_syscall != 0 || (size_t) (int) n != n) {
+                r = getrandom(p, n, GRND_NONBLOCK);
+                if (r == (int) n) {
+                        have_syscall = true;
+                        return 0;
+                }
+
+                if (r < 0) {
+                        if (errno == ENOSYS)
+                                /* we lack the syscall, continue with
+                                 * reading from /dev/urandom */
+                                have_syscall = false;
+                        else if (errno == EAGAIN)
+                                /* not enough entropy for now. Let's
+                                 * remember to use the syscall the
+                                 * next time, again, but also read
+                                 * from /dev/urandom for now, which
+                                 * doesn't care about the current
+                                 * amount of entropy.  */
+                                have_syscall = true;
+                        else
+                                return -errno;
+                } else
+                        /* too short read? */
+                        return -ENODATA;
+        }
+
+        fd = open("/dev/urandom", O_RDONLY|O_CLOEXEC|O_NOCTTY);
+        if (fd < 0)
+                return errno == ENOENT ? -ENOSYS : -errno;
+
+        return loop_read_exact(fd, p, n, true);
+}
+
+void initialize_srand(void) {
+        static bool srand_called = false;
+        unsigned x;
+#ifdef HAVE_SYS_AUXV_H
+        void *auxv;
+#endif
+
+        if (srand_called)
+                return;
+
+        x = 0;
+
+#ifdef HAVE_SYS_AUXV_H
+        /* The kernel provides us with a bit of entropy in auxv, so
+         * let's try to make use of that to seed the pseudo-random
+         * generator. It's better than nothing... */
+
+        auxv = (void*) getauxval(AT_RANDOM);
+        if (auxv)
+                x ^= *(unsigned*) auxv;
+#endif
+
+        x ^= (unsigned) now(CLOCK_REALTIME);
+        x ^= (unsigned) gettid();
+
+        srand(x);
+        srand_called = true;
+}
+
+void random_bytes(void *p, size_t n) {
+        uint8_t *q;
+        int r;
+
+        r = dev_urandom(p, n);
+        if (r >= 0)
+                return;
+
+        /* If some idiot made /dev/urandom unavailable to us, he'll
+         * get a PRNG instead. */
+
+        initialize_srand();
+
+        for (q = p; q < (uint8_t*) p + n; q ++)
+                *q = rand();
+}
diff --git a/src/shared/random-util.h b/src/shared/random-util.h
new file mode 100644
index 0000000000..f7862c8c8b
--- /dev/null
+++ b/src/shared/random-util.h
@@ -0,0 +1,38 @@
+#pragma once
+
+/***
+  This file is part of systemd.
+
+  Copyright 2010 Lennart Poettering
+
+  systemd is free software; you can redistribute it and/or modify it
+  under the terms of the GNU Lesser General Public License as published by
+  the Free Software Foundation; either version 2.1 of the License, or
+  (at your option) any later version.
+
+  systemd is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public License
+  along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+#include <stdint.h>
+
+int dev_urandom(void *p, size_t n);
+void random_bytes(void *p, size_t n);
+void initialize_srand(void);
+
+static inline uint64_t random_u64(void) {
+        uint64_t u;
+        random_bytes(&u, sizeof(u));
+        return u;
+}
+
+static inline uint32_t random_u32(void) {
+        uint32_t u;
+        random_bytes(&u, sizeof(u));
+        return u;
+}
diff --git a/src/shared/util.c b/src/shared/util.c
index d22ab8631f..0b04411f82 100644
--- a/src/shared/util.c
+++ b/src/shared/util.c
@@ -70,6 +70,7 @@
 #include "fileio.h"
 #include "virt.h"
 #include "process-util.h"
+#include "random-util.h"
 
 /* Put this test here for a lack of better place */
 assert_cc(EAGAIN == EWOULDBLOCK);
@@ -719,6 +720,17 @@ ssize_t loop_read(int fd, void *buf, size_t nbytes, bool do_poll) {
         return n;
 }
 
+int loop_read_exact(int fd, void *buf, size_t nbytes, bool do_poll) {
+        ssize_t n;
+
+        n = loop_read(fd, buf, nbytes, do_poll);
+        if (n < 0)
+                return n;
+        if ((size_t) n != nbytes)
+                return -EIO;
+        return 0;
+}
+
 char* dirname_malloc(const char *path) {
         char *d, *dir, *dir2;
 
@@ -737,108 +749,6 @@ char* dirname_malloc(const char *path) {
         return dir;
 }
 
-int dev_urandom(void *p, size_t n) {
-        static int have_syscall = -1;
-        int r, fd;
-        ssize_t k;
-
-        /* Gathers some randomness from the kernel. This call will
-         * never block, and will always return some data from the
-         * kernel, regardless if the random pool is fully initialized
-         * or not. It thus makes no guarantee for the quality of the
-         * returned entropy, but is good enough for or usual usecases
-         * of seeding the hash functions for hashtable */
-
-        /* Use the getrandom() syscall unless we know we don't have
-         * it, or when the requested size is too large for it. */
-        if (have_syscall != 0 || (size_t) (int) n != n) {
-                r = getrandom(p, n, GRND_NONBLOCK);
-                if (r == (int) n) {
-                        have_syscall = true;
-                        return 0;
-                }
-
-                if (r < 0) {
-                        if (errno == ENOSYS)
-                                /* we lack the syscall, continue with
-                                 * reading from /dev/urandom */
-                                have_syscall = false;
-                        else if (errno == EAGAIN)
-                                /* not enough entropy for now. Let's
-                                 * remember to use the syscall the
-                                 * next time, again, but also read
-                                 * from /dev/urandom for now, which
-                                 * doesn't care about the current
-                                 * amount of entropy.  */
-                                have_syscall = true;
-                        else
-                                return -errno;
-                } else
-                        /* too short read? */
-                        return -EIO;
-        }
-
-        fd = open("/dev/urandom", O_RDONLY|O_CLOEXEC|O_NOCTTY);
-        if (fd < 0)
-                return errno == ENOENT ? -ENOSYS : -errno;
-
-        k = loop_read(fd, p, n, true);
-        safe_close(fd);
-
-        if (k < 0)
-                return (int) k;
-        if ((size_t) k != n)
-                return -EIO;
-
-        return 0;
-}
-
-void initialize_srand(void) {
-        static bool srand_called = false;
-        unsigned x;
-#ifdef HAVE_SYS_AUXV_H
-        void *auxv;
-#endif
-
-        if (srand_called)
-                return;
-
-        x = 0;
-
-#ifdef HAVE_SYS_AUXV_H
-        /* The kernel provides us with a bit of entropy in auxv, so
-         * let's try to make use of that to seed the pseudo-random
-         * generator. It's better than nothing... */
-
-        auxv = (void*) getauxval(AT_RANDOM);
-        if (auxv)
-                x ^= *(unsigned*) auxv;
-#endif
-
-        x ^= (unsigned) now(CLOCK_REALTIME);
-        x ^= (unsigned) gettid();
-
-        srand(x);
-        srand_called = true;
-}
-
-void random_bytes(void *p, size_t n) {
-        uint8_t *q;
-        int r;
-
-        r = dev_urandom(p, n);
-        if (r >= 0)
-                return;
-
-        /* If some idiot made /dev/urandom unavailable to us, he'll
-         * get a PRNG instead. */
-
-        initialize_srand();
-
-        for (q = p; q < (uint8_t*) p + n; q ++)
-                *q = rand();
-}
-
 _pure_ static int is_temporary_fs(struct statfs *s) {
         assert(s);
 
diff --git a/src/shared/util.h b/src/shared/util.h
index 0f97873d8b..c5e535069c 100644
--- a/src/shared/util.h
+++ b/src/shared/util.h
@@ -160,10 +160,6 @@ bool dirent_is_file_with_suffix(const struct dirent *de, const char *suffix) _pu
 
 bool hidden_file(const char *filename) _pure_;
 
-int dev_urandom(void *p, size_t n);
-void random_bytes(void *p, size_t n);
-void initialize_srand(void);
-
 /* For basic lookup tables with strictly enumerated entries */
 #define _DEFINE_STRING_TABLE_LOOKUP_TO_STRING(name,type,scope)          \
         scope const char *name##_to_string(type i) {                    \
@@ -234,6 +230,7 @@ int flush_fd(int fd);
 int fopen_temporary(const char *path, FILE **_f, char **_temp_path);
 
 ssize_t loop_read(int fd, void *buf, size_t nbytes, bool do_poll);
+int loop_read_exact(int fd, void *buf, size_t nbytes, bool do_poll);
 
 char* dirname_malloc(const char *path);