Make libcrypt thread-safe. Add crypt_r(3).

glibc has a pretty nice function called crypt_r(3), which is nothing
more than crypt(3), but thread-safe. It accomplishes this by introducing
a 'struct crypt_data' structure that contains a buffer that is large
enough to hold the resulting string.

Let's go ahead and also add this function. It would be a shame if a
useful function like this wouldn't be usable in multithreaded apps.
Refactor crypt.c and all of the backends to no longer declare static
arrays, but write their output in a provided buffer.

There is no need to do any buffer length computation here, as we'll just
need to ensure that 'struct crypt_data' is large enough, which it is.
_PASSWORD_LEN is defined to 128 bytes, but in this case I'm picking 256,
as this is going to be part of the actual ABI.

Differential Revision:	https://reviews.freebsd.org/D7306

1 files changed, 7 insertions, 0 deletions

diff --git a/include/unistd.h b/include/unistd.h
index 0d20027f8d56a..0fb36e50e050e 100644
--- a/include/unistd.h
+++ b/include/unistd.h
@@ -484,11 +484,18 @@ pid_t	 vfork(void) __returns_twice;
 
 #if __BSD_VISIBLE
 struct timeval;				/* select(2) */
+
+struct crypt_data {
+	int	initialized;	/* For compatibility with glibc. */
+	char	__buf[256];	/* Buffer returned by crypt_r(). */
+};
+
 int	 acct(const char *);
 int	 async_daemon(void);
 int	 check_utility_compat(const char *);
 const char *
 	 crypt_get_format(void);
+char	*crypt_r(const char *, const char *, struct crypt_data *);
 int	 crypt_set_format(const char *);
 int	 des_cipher(const char *, char *, long, int);
 int	 des_setkey(const char *key);