Massively extend libulog:

- Just like struct utmp, store strings inside struct utmpx itself. This
  is needed to make things like pututxline() work.
- Add ut_id and ut_pid fields, even though they have little use in our
  implementation.
- It turns out our "reboot" wtmp entries indicate a system boot, so
  remove REBOOT_TIME
- Implement getutxline() and pututxline
- Add getutxuser() and setutxfile(), which allows us to crawl wtmp and
  lastlog files as well.
- Add _ULOG_POSIX_NAMES, so we can already use the POSIX names if we
  really want to.

1 files changed, 238 insertions, 35 deletions

diff --git a/lib/libulog/ulog_getutxent.c b/lib/libulog/ulog_getutxent.c
index 1dd464d..7ffc739 100644
--- a/lib/libulog/ulog_getutxent.c
+++ b/lib/libulog/ulog_getutxent.c
@@ -27,6 +27,9 @@
 #include <sys/cdefs.h>
 __FBSDID("$FreeBSD$");
 
+#include <sys/param.h>
+
+#include <pwd.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -35,6 +38,7 @@ __FBSDID("$FreeBSD$");
 #include "ulog_internal.h"
 
 static FILE *ufile;
+static int ufiletype = -1;
 
 void
 ulog_endutxent(void)
@@ -44,56 +48,255 @@ ulog_endutxent(void)
 	ufile = NULL;
 }
 
-struct ulog_utmpx *
-ulog_getutxent(void)
-{
-	struct futmp ut;
-	static struct ulog_utmpx utx;
+/*
+ * Conversion from on-disk formats to generic ulog_utmpx structure.
+ */
 
-	/* Open the utmp file if not already done so. */
-	if (ufile == NULL)
-		ulog_setutxent();
-	if (ufile == NULL)
-		return (NULL);
+static void
+ulog_futmp_to_utmpx(const struct futmp *ut, struct ulog_utmpx *utx)
+{
 
-	if (fread(&ut, sizeof ut, 1, ufile) != 1)
-		return (NULL);
-#define	COPY_STRING(field) do {					\
-	free(utx.ut_ ## field); 				\
-	utx.ut_ ## field = strndup(ut.ut_ ## field,		\
-	    sizeof ut.ut_ ## field);				\
-	if (utx.ut_ ## field == NULL)				\
-		utx.ut_ ## field = __DECONST(char *, "");	\
+	memset(utx, 0, sizeof *utx);
+#define	COPY_STRING(field) do {						\
+	strncpy(utx->ut_ ## field, ut->ut_ ## field,			\
+	    MIN(sizeof utx->ut_ ## field - 1, sizeof ut->ut_ ## field));\
 } while (0)
 	COPY_STRING(user);
 	COPY_STRING(line);
 	COPY_STRING(host);
-	utx.ut_tv.tv_sec = _time32_to_time(ut.ut_time);
-	utx.ut_tv.tv_usec = 0;
-#define	MATCH(field, value)	(strcmp(utx.ut_ ## field, (value)) == 0)
-	if (MATCH(user, "date") && MATCH(line, "|"))
-		utx.ut_type = OLD_TIME;
+#undef COPY_STRING
+#define	MATCH(field, value)	(strcmp(utx->ut_ ## field, (value)) == 0)
+	if (MATCH(user, "reboot") && MATCH(line, "~"))
+		utx->ut_type = BOOT_TIME;
+	else if (MATCH(user, "date") && MATCH(line, "|"))
+		utx->ut_type = OLD_TIME;
 	else if (MATCH(user, "date") && MATCH(line, "{"))
-		utx.ut_type = NEW_TIME;
+		utx->ut_type = NEW_TIME;
 	else if (MATCH(user, "shutdown") && MATCH(line, "~"))
-		utx.ut_type = SHUTDOWN_TIME;
-	else if (MATCH(user, "reboot") && MATCH(line, "~"))
-		utx.ut_type = REBOOT_TIME;
+		utx->ut_type = SHUTDOWN_TIME;
 	else if (MATCH(user, "") && MATCH(host, ""))
-		utx.ut_type = DEAD_PROCESS;
-	else if (!MATCH(user, ""))
-		utx.ut_type = USER_PROCESS;
+		utx->ut_type = DEAD_PROCESS;
+	else if (!MATCH(user, "") && !MATCH(line, "") && ut->ut_time != 0)
+		utx->ut_type = USER_PROCESS;
 	else
-		utx.ut_type = EMPTY;
-	
+		utx->ut_type = EMPTY;
+	utx->ut_tv.tv_sec = _time32_to_time(ut->ut_time);
+	utx->ut_tv.tv_usec = 0;
+}
+
+static void
+ulog_flastlog_to_utmpx(const struct flastlog *ll, struct ulog_utmpx *utx)
+{
+
+	memset(utx, 0, sizeof *utx);
+#define	COPY_STRING(field) do {						\
+	strncpy(utx->ut_ ## field, ll->ll_ ## field,			\
+	    MIN(sizeof utx->ut_ ## field - 1, sizeof ll->ll_ ## field));\
+} while (0)
+	COPY_STRING(line);
+	COPY_STRING(host);
+#undef COPY_STRING
+	if (!MATCH(line, "") && ll->ll_time != 0)
+		utx->ut_type = USER_PROCESS;
+	else
+		utx->ut_type = EMPTY;
+	utx->ut_tv.tv_sec = _time32_to_time(ll->ll_time);
+	utx->ut_tv.tv_usec = 0;
+}
+
+/*
+ * File I/O.
+ */
+
+static inline off_t
+ulog_tell(void)
+{
+
+	if (ufiletype == UTXF_LASTLOG)
+		return (ftello(ufile) / sizeof(struct flastlog));
+	else
+		return (ftello(ufile) / sizeof(struct futmp));
+}
+
+static struct ulog_utmpx *
+ulog_read(off_t off, int whence, int resolve_user)
+{
+	static struct ulog_utmpx utx;
+
+	if (ufile == NULL)
+		ulog_setutxent();
+	if (ufile == NULL)
+		return (NULL);
+
+	/* Only allow seeking to move forward. */
+	if (whence == SEEK_SET && ulog_tell() > off)
+		return (NULL);
+
+	if (ufiletype == UTXF_LASTLOG) {
+		struct flastlog ll;
+		struct passwd *pw = NULL;
+		uid_t uid;
+
+		if (fseeko(ufile, off * sizeof ll, whence) != 0)
+			return (NULL);
+		uid = ulog_tell();
+		if (fread(&ll, sizeof ll, 1, ufile) != 1)
+			return (NULL);
+		ulog_flastlog_to_utmpx(&ll, &utx);
+		if (utx.ut_type == USER_PROCESS && resolve_user)
+			pw = getpwuid(uid);
+		if (pw != NULL)
+			strlcpy(utx.ut_user, pw->pw_name, sizeof utx.ut_user);
+		else
+			sprintf(utx.ut_user, "%u", (unsigned int)uid);
+	} else {
+		struct futmp ut;
+
+		if (fseeko(ufile, off * sizeof(struct futmp), whence) != 0)
+			return (NULL);
+		if (fread(&ut, sizeof ut, 1, ufile) != 1)
+			return (NULL);
+		ulog_futmp_to_utmpx(&ut, &utx);
+	}
 	return (&utx);
 }
 
-void
-ulog_setutxent(void)
+/*
+ * getutxent().
+ *
+ * Read the next entry from the file.
+ */
+
+struct ulog_utmpx *
+ulog_getutxent(void)
+{
+
+	return ulog_read(0, SEEK_CUR, 1);
+}
+
+/*
+ * ulog_getutxline().
+ *
+ * Read entries from the file, until reaching an entry which matches the
+ * provided TTY device name.  We can optimize the case for utmp files,
+ * because they are indexed by TTY device name.
+ */
+
+struct ulog_utmpx *
+ulog_getutxline(const struct ulog_utmpx *line)
 {
+	struct ulog_utmpx *utx;
+
+	if (ufile == NULL)
+		ulog_setutxent();
+	if (ufile == NULL)
+		return (NULL);
+
+	if (ufiletype == UTXF_UTMP) {
+		unsigned int slot;
+
+		slot = ulog_ttyslot(line->ut_line);
+		if (slot == 0)
+			return (NULL);
+		utx = ulog_read(slot, SEEK_SET, 1);
+		if (utx->ut_type == USER_PROCESS &&
+		    strcmp(utx->ut_line, line->ut_line) == 0)
+			return (utx);
+		return (NULL);
+	} else {
+		for (;;) {
+			utx = ulog_read(0, SEEK_CUR, 1);
+			if (utx == NULL)
+				return (NULL);
+			if (utx->ut_type == USER_PROCESS &&
+			    strcmp(utx->ut_line, line->ut_line) == 0)
+				return (utx);
+		}
+	}
+}
+
+/*
+ * ulog_getutxuser().
+ *
+ * Read entries from the file, until reaching an entry which matches the
+ * provided username.  We can optimize the case for lastlog files,
+ * because they are indexed by user ID.
+ */
+
+struct ulog_utmpx *
+ulog_getutxuser(const char *user)
+{
+	struct ulog_utmpx *utx;
+
+	if (ufiletype == UTXF_LASTLOG) {
+		struct passwd *pw;
+
+		pw = getpwnam(user);
+		if (pw == NULL)
+			return (NULL);
+		utx = ulog_read(pw->pw_uid, SEEK_SET, 0);
+		if (utx != NULL)
+			strlcpy(utx->ut_user, user, sizeof utx->ut_user);
+		return (utx);
+	} else {
+		for (;;) {
+			utx = ulog_read(0, SEEK_CUR, 1);
+			if (utx == NULL)
+				return (NULL);
+			if (utx->ut_type == USER_PROCESS &&
+			    strcmp(utx->ut_user, user) == 0)
+				return (utx);
+		}
+	}
+}
+
+/*
+ * ulog_setutxfile().
+ *
+ * Switch to a different record file.  When no filename is provided, the
+ * system default is opened.
+ */
+
+int
+ulog_setutxfile(int type, const char *file)
+{
+
+	/* Supply default files. */
+	switch (type) {
+	case UTXF_UTMP:
+		if (file == NULL)
+			file = _PATH_UTMP;
+		break;
+	case UTXF_WTMP:
+		if (file == NULL)
+			file = _PATH_WTMP;
+		break;
+	case UTXF_LASTLOG:
+		if (file == NULL)
+			file = _PATH_LASTLOG;
+		break;
+	default:
+		return (-1);
+	}
 
 	if (ufile != NULL)
 		fclose(ufile);
-	ufile = fopen(_PATH_UTMP, "r");
+	ufile = fopen(file, "r");
+	ufiletype = type;
+	if (ufile == NULL)
+		return (-1);
+	return (0);
+}
+
+/*
+ * ulog_endutxfile().
+ *
+ * Close any opened files.
+ */
+
+void
+ulog_setutxent(void)
+{
+
+	ulog_setutxfile(UTXF_UTMP, NULL);
 }