Perform several small cleanups to the utmpx code.

- Massively reduce BSS usage. Let futx_to_utx() dynamically allocate the
  structure. There is only a very small amount of applications out there
  that needs to use the utmpx database. Wasting 1 KB on unused
  structures makes little sense.

- Just let getutxid() search for matching ut_id's for any *PROCESS-type.
  This makes the code a bit more future-proof.

- Fix a POSIX-mistake: when reading POSIX and the OpenSolaris
  implementation, getutxline() must return USER_PROCESS and
  LOGIN_PROCESS records whose ut_lines match. When reading POSIX, it
  seems LOGIN_PROCESS should not use ut_line at the first place. I have
  reported this issue.

5 files changed, 62 insertions, 60 deletions

diff --git a/lib/libc/gen/getutxent.3 b/lib/libc/gen/getutxent.3
index c37240e..58b1280 100644
--- a/lib/libc/gen/getutxent.3
+++ b/lib/libc/gen/getutxent.3
@@ -174,7 +174,9 @@ prefix, corresponding with the device used to facilitate the user login
 session.
 If no TTY character device is used, this field is left blank.
 This field is only applicable to entries of type
-.Dv USER_PROCESS .
+.Dv USER_PROCESS 
+and
+.Dv LOGIN_PROCESS .
 .It Fa ut_host
 The network hostname of the remote system, connecting to perform a user
 login.
diff --git a/lib/libc/gen/getutxent.c b/lib/libc/gen/getutxent.c
index 08b120bae..654a634 100644
--- a/lib/libc/gen/getutxent.c
+++ b/lib/libc/gen/getutxent.c
@@ -40,7 +40,6 @@ __FBSDID("$FreeBSD$");
 
 static FILE *uf = NULL;
 static int udb;
-static struct utmpx utx;
 
 int
 setutxdb(int db, const char *file)
@@ -101,70 +100,59 @@ endutxent(void)
 	}
 }
 
-static struct futx *
-getfutxent(void)
+static int
+getfutxent(struct futx *fu)
 {
-	static struct futx fu;
 
 	if (uf == NULL)
 		setutxent();
 	if (uf == NULL)
-		return (NULL);
+		return (-1);
 
 	if (udb == UTXDB_LOG) {
 		uint16_t len;
 
 		if (fread(&len, sizeof len, 1, uf) != 1)
-			return (NULL);
+			return (-1);
 		len = be16toh(len);
-		if (len > sizeof fu) {
+		if (len > sizeof *fu) {
 			/* Forward compatibility. */
-			if (fread(&fu, sizeof fu, 1, uf) != 1)
-				return (NULL);
-			fseek(uf, len - sizeof fu, SEEK_CUR);
+			if (fread(fu, sizeof *fu, 1, uf) != 1)
+				return (-1);
+			fseek(uf, len - sizeof *fu, SEEK_CUR);
 		} else {
 			/* Partial record. */
-			memset(&fu, 0, sizeof fu);
-			if (fread(&fu, len, 1, uf) != 1)
-				return (NULL);
+			memset(fu, 0, sizeof *fu);
+			if (fread(fu, len, 1, uf) != 1)
+				return (-1);
 		}
 	} else {
-		if (fread(&fu, sizeof fu, 1, uf) != 1)
-			return (NULL);
+		if (fread(fu, sizeof *fu, 1, uf) != 1)
+			return (-1);
 	}
-	return (&fu);
+	return (0);
 }
 
 struct utmpx *
 getutxent(void)
 {
-	struct futx *fu;
+	struct futx fu;
 
-	fu = getfutxent();
-	if (fu == NULL)
+	if (getfutxent(&fu) != 0)
 		return (NULL);
-	futx_to_utx(fu, &utx);
-	return (&utx);
+	return (futx_to_utx(&fu));
 }
 
 struct utmpx *
 getutxid(const struct utmpx *id)
 {
-	struct futx *fu;
+	struct futx fu;
 
 	for (;;) {
-		fu = getfutxent();
-		if (fu == NULL)
+		if (getfutxent(&fu) != 0)
 			return (NULL);
 
-		switch (fu->fu_type) {
-		case BOOT_TIME:
-		case OLD_TIME:
-		case NEW_TIME:
-		case SHUTDOWN_TIME:
-			if (fu->fu_type == id->ut_type)
-				goto found;
-			break;
+		switch (fu.fu_type) {
 		case USER_PROCESS:
 		case INIT_PROCESS:
 		case LOGIN_PROCESS:
@@ -174,61 +162,62 @@ getutxid(const struct utmpx *id)
 			case INIT_PROCESS:
 			case LOGIN_PROCESS:
 			case DEAD_PROCESS:
-				if (memcmp(fu->fu_id, id->ut_id,
-				    MIN(sizeof fu->fu_id, sizeof id->ut_id)) == 0)
+				if (memcmp(fu.fu_id, id->ut_id,
+				    MIN(sizeof fu.fu_id, sizeof id->ut_id)) == 0)
 					goto found;
 			}
 			break;
+		default:
+			if (fu.fu_type == id->ut_type)
+				goto found;
+			break;
 		}
 	}
 
 found:
-	futx_to_utx(fu, &utx);
-	return (&utx);
+	return (futx_to_utx(&fu));
 }
 
 struct utmpx *
 getutxline(const struct utmpx *line)
 {
-	struct futx *fu;
+	struct futx fu;
 
 	for (;;) {
-		fu = getfutxent();
-		if (fu == NULL)
+		if (getfutxent(&fu) != 0)
 			return (NULL);
 
-		switch (fu->fu_type) {
+		switch (fu.fu_type) {
 		case USER_PROCESS:
 		case LOGIN_PROCESS:
-			if (strncmp(fu->fu_line, line->ut_line,
-			    MIN(sizeof fu->fu_line, sizeof line->ut_line)) == 0)
+			if (strncmp(fu.fu_line, line->ut_line,
+			    MIN(sizeof fu.fu_line, sizeof line->ut_line)) == 0)
 				goto found;
+			break;
 		}
 	}
 
 found:
-	futx_to_utx(fu, &utx);
-	return (&utx);
+	return (futx_to_utx(&fu));
 }
 
 struct utmpx *
 getutxuser(const char *user)
 {
-	struct futx *fu;
+	struct futx fu;
 
 	for (;;) {
-		fu = getfutxent();
-		if (fu == NULL)
+		if (getfutxent(&fu) != 0)
 			return (NULL);
 
-		switch (fu->fu_type) {
+		switch (fu.fu_type) {
 		case USER_PROCESS:
-			if (strncmp(fu->fu_user, user, sizeof fu->fu_user) == 0)
+			if (strncmp(fu.fu_user, user, sizeof fu.fu_user) == 0)
 				goto found;
+			break;
 		}
 	}
 
 found:
-	futx_to_utx(fu, &utx);
-	return (&utx);
+	return (futx_to_utx(&fu));
 }
diff --git a/lib/libc/gen/pututxline.c b/lib/libc/gen/pututxline.c
index 94c63bd..1239531 100644
--- a/lib/libc/gen/pututxline.c
+++ b/lib/libc/gen/pututxline.c
@@ -240,7 +240,6 @@ struct utmpx *
 pututxline(const struct utmpx *utmpx)
 {
 	struct futx fu;
-	static struct utmpx ut;
 
 	utx_to_futx(utmpx, &fu);
 	
@@ -272,6 +271,5 @@ pututxline(const struct utmpx *utmpx)
 	}
 
 	utx_log_add(&fu);
-	futx_to_utx(&fu, &ut);
-	return (&ut);
+	return (futx_to_utx(&fu));
 }
diff --git a/lib/libc/gen/utxdb.c b/lib/libc/gen/utxdb.c
index d7e2b34..224d86b 100644
--- a/lib/libc/gen/utxdb.c
+++ b/lib/libc/gen/utxdb.c
@@ -30,6 +30,7 @@ __FBSDID("$FreeBSD$");
 #include "namespace.h"
 #include <sys/endian.h>
 #include <sys/param.h>
+#include <stdlib.h>
 #include <string.h>
 #include <utmpx.h>
 #include "utxdb.h"
@@ -82,6 +83,8 @@ utx_to_futx(const struct utmpx *ut, struct futx *fu)
 	case LOGIN_PROCESS:
 		UTOF_ID(ut, fu);
 		UTOF_STRING(ut, fu, user);
+		/* XXX: bug in the specification? Needed for getutxline(). */
+		UTOF_STRING(ut, fu, line);
 		UTOF_PID(ut, fu);
 		break;
 	case DEAD_PROCESS:
@@ -118,11 +121,18 @@ utx_to_futx(const struct utmpx *ut, struct futx *fu)
 	(ut)->ut_tv.tv_usec = t % 1000000;				\
 } while (0)
 
-void
-futx_to_utx(const struct futx *fu, struct utmpx *ut)
+struct utmpx *
+futx_to_utx(const struct futx *fu)
 {
+	static struct utmpx *ut;
 
-	memset(ut, 0, sizeof *ut);
+	if (ut == NULL) {
+		ut = calloc(1, sizeof *ut);
+		if (ut == NULL)
+			return (NULL);
+	} else {
+		memset(ut, 0, sizeof *ut);
+	}
 
 	switch (fu->fu_type) {
 	case BOOT_TIME:
@@ -146,6 +156,8 @@ futx_to_utx(const struct futx *fu, struct utmpx *ut)
 	case LOGIN_PROCESS:
 		FTOU_ID(fu, ut);
 		FTOU_STRING(fu, ut, user);
+		/* XXX: bug in the specification? Needed for getutxline(). */
+		FTOU_STRING(fu, ut, line);
 		FTOU_PID(fu, ut);
 		break;
 	case DEAD_PROCESS:
@@ -154,9 +166,10 @@ futx_to_utx(const struct futx *fu, struct utmpx *ut)
 		break;
 	default:
 		ut->ut_type = EMPTY;
-		return;
+		return (ut);
 	}
 
 	FTOU_TYPE(fu, ut);
 	FTOU_TV(fu, ut);
+	return (ut);
 }
diff --git a/lib/libc/gen/utxdb.h b/lib/libc/gen/utxdb.h
index ec02013..d9ebc93 100644
--- a/lib/libc/gen/utxdb.h
+++ b/lib/libc/gen/utxdb.h
@@ -56,6 +56,6 @@ struct futx {
 } __packed;
 
 void	utx_to_futx(const struct utmpx *, struct futx *);
-void	futx_to_utx(const struct futx *, struct utmpx *);
+struct utmpx *futx_to_utx(const struct futx *);
 
 #endif /* !_UTXDB_H_ */