Move csrand() to a new file csrand.c

A set of APIs similar to arc4random(3) is complex enough to deserve its
own file.

Cc: "Jason A. Donenfeld" <Jason@zx2c4.com>
Cc: Cristian Rodríguez <crrodriguez@opensuse.org>
Cc: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Cc: Björn Esser <besser82@fedoraproject.org>
Cc: Yann Droneaud <ydroneaud@opteya.com>
Cc: Joseph Myers <joseph@codesourcery.com>
Signed-off-by: Alejandro Colomar <alx@kernel.org>

lib/prototypes.h

@@ -356,6 +356,9 @@ extern /*@dependent@*/ /*@null@*/struct commonio_entry *__pw_get_head (void);
 extern /*@null@*/ /*@only@*/struct passwd *__pw_dup (const struct passwd *pwent);
 extern void pw_free (/*@out@*/ /*@only@*/struct passwd *pwent);
 
+/* csrand.c */
+unsigned long csrand (void);
+
 /* remove_tree.c */
 extern int remove_tree (const char *root, bool remove_root);
 

libmisc/Makefile.am

@@ -52,6 +52,7 @@ libmisc_la_SOURCES = \
 	pwd2spwd.c \
 	pwdcheck.c \
 	pwd_init.c \
+	csrand.c \
 	remove_tree.c \
 	rlogin.c \
 	root_flag.c \

libmisc/csrand.c

@@ -0,0 +1,61 @@
+#include <config.h>
+
+#ident "$Id$"
+
+#include <limits.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#if HAVE_SYS_RANDOM_H
+#include <sys/random.h>
+#endif
+#include "bit.h"
+#include "prototypes.h"
+#include "shadowlog.h"
+
+
+/*
+ * Return a uniformly-distributed CS random u_long value.
+ */
+unsigned long
+csrand(void)
+{
+	FILE           *fp;
+	unsigned long  r;
+
+#ifdef HAVE_GETENTROPY
+	/* getentropy may exist but lack kernel support.  */
+	if (getentropy(&r, sizeof(r)) == 0)
+		return r;
+#endif
+
+#ifdef HAVE_GETRANDOM
+	/* Likewise getrandom.  */
+	if (getrandom(&r, sizeof(r), 0) == sizeof(r))
+		return r;
+#endif
+
+#ifdef HAVE_ARC4RANDOM_BUF
+	/* arc4random_buf can never fail.  */
+	arc4random_buf(&r, sizeof(r));
+	return r;
+#endif
+
+	/* Use /dev/urandom as a last resort.  */
+	fp = fopen("/dev/urandom", "r");
+	if (NULL == fp) {
+		goto fail;
+	}
+
+	if (fread(&r, sizeof(r), 1, fp) != 1) {
+		fclose(fp);
+		goto fail;
+	}
+
+	fclose(fp);
+	return r;
+
+fail:
+	fprintf(log_get_logfd(), _("Unable to obtain random bytes.\n"));
+	exit(1);
+}

libmisc/salt.c

@@ -20,9 +20,6 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
-#if HAVE_SYS_RANDOM_H
-#include <sys/random.h>
-#endif
 #include "prototypes.h"
 #include "defines.h"
 #include "getdef.h"
@@ -89,7 +86,6 @@
 #define GENSALT_SETTING_SIZE 100
 
 /* local function prototypes */
-static long csrand (void);
 #if !USE_XCRYPT_GENSALT
 static /*@observer@*/const char *gensalt (size_t salt_size);
 #endif /* !USE_XCRYPT_GENSALT */
@@ -109,53 +105,6 @@ static /*@observer@*/unsigned long YESCRYPT_get_salt_cost (/*@null@*/const int *
 static /*@observer@*/void YESCRYPT_salt_cost_to_buf (char *buf, unsigned long cost);
 #endif /* USE_YESCRYPT */
 
-/* Read sizeof (long) random bytes from /dev/urandom. */
-static long csrand (void)
-{
-	long randval = 0;
-
-#ifdef HAVE_GETENTROPY
-	/* getentropy may exist but lack kernel support.  */
-	if (getentropy (&randval, sizeof (randval)) == 0) {
-		goto end;
-	}
-#endif
-
-#ifdef HAVE_GETRANDOM
-	/* Likewise getrandom.  */
-	if ((size_t) getrandom (&randval, sizeof (randval), 0) == sizeof (randval)) {
-		goto end;
-	}
-#endif
-
-#ifdef HAVE_ARC4RANDOM_BUF
-	/* arc4random_buf, if it exists, can never fail.  */
-	arc4random_buf (&randval, sizeof (randval));
-	goto end;
-#endif
-
-	/* Use /dev/urandom as a last resort.  */
-	FILE *f = fopen ("/dev/urandom", "r");
-	if (NULL == f) {
-		goto fail;
-	}
-
-	if (fread (&randval, sizeof (randval), 1, f) != 1) {
-		fclose(f);
-		goto fail;
-	}
-
-	fclose(f);
-	goto end;
-
-fail:
-	fprintf (log_get_logfd(),
-		 _("Unable to obtain random bytes.\n"));
-	exit (1);
-
-end:
-	return randval;
-}
 
 #if defined(USE_SHA_CRYPT) || defined(USE_BCRYPT)
 /*