last: optional alternative sysv-like implementation

(by Patricia Muscalu <patricia.muscalu AT axis.com>)

function                                             old     new   delta
last_main                                            448     917    +469
show_entry                                             -     319    +319
packed_usage                                       24216   24268     +52
------------------------------------------------------------------------------
(add/remove: 1/0 grow/shrink: 2/0 up/down: 840/0)             Total: 840 bytes

4 files changed, 307 insertions, 2 deletions

diff --git a/include/usage.h b/include/usage.h
index cffe78220..1f4213a2e 100644
--- a/include/usage.h
+++ b/include/usage.h
@@ -3504,9 +3504,15 @@
        "lash is deprecated, please use hush"
 
 #define last_trivial_usage \
-       ""
+       ""USE_FEATURE_LAST_FANCY("[-HW] [-f file]")
 #define last_full_usage "\n\n" \
-       "Show listing of the last users that logged into the system"
+       "Show listing of the last users that logged into the system" \
+        USE_FEATURE_LAST_FANCY( "\n" \
+     "\nOptions:" \
+     "\n        -H              Show header line" \
+     "\n        -W              Display with no host column truncation" \
+     "\n        -f file         Read from file instead of /var/log/wtmp" \
+        )
 
 #define sha1sum_trivial_usage \
        "[OPTION] [FILEs...]" \
diff --git a/miscutils/Config.in b/miscutils/Config.in
index c4eb10838..427906ff8 100644
--- a/miscutils/Config.in
+++ b/miscutils/Config.in
@@ -229,6 +229,14 @@ config LAST
         help
           'last' displays a list of the last users that logged into the system.
 
+config FEATURE_LAST_FANCY
+        bool "Fancy output"
+        default n
+        depends on LAST
+        help
+          'last' displays detailed information about the last users that
+          logged into the system (mimics sysvinit last). +900 bytes.
+
 config LESS
         bool "less"
         default n
diff --git a/miscutils/last.c b/miscutils/last.c
index 749862c35..ef41444c5 100644
--- a/miscutils/last.c
+++ b/miscutils/last.c
@@ -26,6 +26,12 @@
 #error struct utmp member char[] size(s) have changed!
 #endif
 
+#if ENABLE_FEATURE_LAST_FANCY
+
+#include "last_fancy.c"
+
+#else
+
 int last_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 int last_main(int argc, char **argv ATTRIBUTE_UNUSED)
 {
@@ -92,3 +98,5 @@ int last_main(int argc, char **argv ATTRIBUTE_UNUSED)
 
         fflush_stdout_and_exit(EXIT_SUCCESS);
 }
+
+#endif
diff --git a/miscutils/last_fancy.c b/miscutils/last_fancy.c
new file mode 100644
index 000000000..0ad2b9245
--- /dev/null
+++ b/miscutils/last_fancy.c
@@ -0,0 +1,283 @@
+/* vi: set sw=4 ts=4: */
+/*
+ * (sysvinit like) last implementation
+ *
+ * Copyright (C) 2008 by Patricia Muscalu <patricia.muscalu@axis.com>
+ *
+ * Licensed under the GPLv2 or later, see the file LICENSE in this tarball.
+ */
+
+#define HEADER_FORMAT     "%-8.8s %-12.12s %-*.*s %-16.16s %-7.7s %-12.12s\n"
+#define HEADER_LINE       "USER", "TTY", \
+        INET_ADDRSTRLEN, INET_ADDRSTRLEN, "HOST", "LOGIN", "  TIME", ""
+#define HEADER_LINE_WIDE  "USER", "TTY", \
+        INET6_ADDRSTRLEN, INET6_ADDRSTRLEN, "HOST", "LOGIN", "  TIME", ""
+
+enum {
+        NORMAL,
+        LOGGED,
+        DOWN,
+        REBOOT,
+        CRASH,
+        GONE
+};
+
+enum {
+        LAST_OPT_W = (1 << 0),  /* -W wide            */
+        LAST_OPT_f = (1 << 1),  /* -f input file      */
+        LAST_OPT_H = (1 << 2),  /* -H header          */
+};
+
+#define show_wide (option_mask32 & LAST_OPT_W)
+
+static void show_entry(struct utmp *ut, int state, time_t dur_secs)
+{
+        unsigned days, hours, mins;
+        char duration[32];
+        char login_time[17];
+        char logout_time[8];
+        const char *logout_str;
+        const char *duration_str;
+
+        safe_strncpy(login_time, ctime(&(ut->ut_time)), 17);
+        snprintf(logout_time, 8, "- %s", ctime(&dur_secs) + 11);
+
+        dur_secs = MAX(dur_secs - (time_t)ut->ut_tv.tv_sec, (time_t)0);
+        /* unsigned int is easier to divide than time_t (which may be signed long) */
+        mins = dur_secs / 60;
+        days = mins / (24*60);
+        mins = mins % (24*60);
+        hours = mins / 60;
+        mins = mins % 60;
+
+        if (days) {
+                sprintf(duration, "(%u+%02u:%02u)", days, hours, mins);
+        } else {
+                sprintf(duration, " (%02u:%02u)", hours, mins);
+        }
+
+        logout_str = logout_time;
+        duration_str = duration;
+        switch (state) {
+        case NORMAL:
+                break;
+        case LOGGED:
+                logout_str = "  still";
+                duration_str = "logged in";
+                break;
+        case DOWN:
+                logout_str = "- down ";
+                break;
+        case REBOOT:
+                break;
+        case CRASH:
+                logout_str = "- crash";
+                break;
+        case GONE:
+                logout_str = "   gone";
+                duration_str = "- no logout";
+                break;
+        }
+
+        printf(HEADER_FORMAT,
+                   ut->ut_name,
+                   ut->ut_line,
+                   show_wide ? INET6_ADDRSTRLEN : INET_ADDRSTRLEN,
+                   show_wide ? INET6_ADDRSTRLEN : INET_ADDRSTRLEN,
+                   ut->ut_host,
+                   login_time,
+                   logout_str,
+                   duration_str);
+}
+
+static int get_ut_type(struct utmp *ut)
+{
+        if (ut->ut_line[0] == '~') {
+                if (strncmp(ut->ut_user, "shutdown", sizeof("shutdown")-1) == 0) {
+                        return SHUTDOWN_TIME;
+                }
+                if (strncmp(ut->ut_user, "reboot", sizeof("reboot")-1) == 0) {
+                        return BOOT_TIME;
+                }
+                if (strncmp(ut->ut_user, "runlevel", sizeof("runlevel")-1) == 0) {
+                        return RUN_LVL;
+                }
+                return ut->ut_type;
+        }
+
+        if (ut->ut_name[0] == 0) {
+                return DEAD_PROCESS;
+        }
+
+        if ((ut->ut_type != DEAD_PROCESS)
+         && (strcmp(ut->ut_name, "LOGIN") != 0)
+         && ut->ut_name[0]
+         && ut->ut_line[0]
+        ) {
+                ut->ut_type = USER_PROCESS;
+        }
+
+        if (strcmp(ut->ut_name, "date") == 0) {
+                if (ut->ut_line[0] == '|') {
+                        return OLD_TIME;
+                }
+                if (ut->ut_line[0] == '{') {
+                        return NEW_TIME;
+                }
+        }
+        return ut->ut_type;
+}
+
+static int is_runlevel_shutdown(struct utmp *ut)
+{
+        if (((ut->ut_pid & 255) == '0') || ((ut->ut_pid & 255) == '6')) {
+                return 1;
+        }
+
+        return 0;
+}
+
+int last_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
+int last_main(int argc ATTRIBUTE_UNUSED, char **argv)
+{
+        struct utmp ut;
+        const char *filename = _PATH_WTMP;
+        llist_t *zlist;
+        off_t pos;
+        time_t start_time;
+        time_t boot_time;
+        time_t down_time;
+        int file;
+        unsigned opt;
+        smallint going_down;
+        smallint boot_down;
+
+        opt = getopt32(argv, "Wf:" /* "H" */, &filename);
+#ifdef BUT_UTIL_LINUX_LAST_HAS_NO_SUCH_OPT
+        if (opt & LAST_OPT_H) {
+                /* Print header line */
+                if (opt & LAST_OPT_W) {
+                        printf(HEADER_FORMAT, HEADER_LINE_WIDE);
+                } else {
+                        printf(HEADER_FORMAT, HEADER_LINE);
+                }
+        }
+#endif
+
+        file = xopen(filename, O_RDONLY);
+        if (full_read(file, &ut, sizeof(ut)) != sizeof(ut)) {
+                struct stat st;
+                fstat(file, &st);
+                start_time = st.st_ctime;
+                goto exit;
+        }
+        start_time = ut.ut_time;
+
+        time(&down_time);
+        going_down = 0;
+        boot_down = NORMAL; /* 0 */
+        zlist = NULL;
+        boot_time = 0;
+        pos = 0;
+        for (;;) {
+                pos -= (off_t)sizeof(ut);
+                /* Bug? What if file changes size?
+                 * What if size is not a multiple of sizeof(ut)? */
+                if (lseek(file, pos, SEEK_END) < 0) {
+                        /* Beyond the beginning of the file boundary =>
+                         * the whole file has been read. */
+                        break;
+                }
+                if (full_read(file, &ut, sizeof(ut)) != sizeof(ut))
+                        break;
+
+                switch (get_ut_type(&ut)) {
+                case SHUTDOWN_TIME:
+                        down_time = ut.ut_time;
+                        boot_down = DOWN;
+                        going_down = 1;
+                        break;
+                case RUN_LVL:
+                        if (is_runlevel_shutdown(&ut)) {
+                                down_time = ut.ut_time;
+                                going_down = 1;
+                                boot_down = DOWN;
+                        }
+                        break;
+                case BOOT_TIME:
+                        strcpy(ut.ut_line, "system boot");
+                        show_entry(&ut, REBOOT, down_time);
+                        boot_down = CRASH;
+                        going_down = 1;
+                        break;
+                case DEAD_PROCESS:
+                        if (!ut.ut_line[0]) {
+                                break;
+                        }
+                        /* add_entry */
+                        llist_add_to(&zlist, memcpy(xmalloc(sizeof(ut)), &ut, sizeof(ut)));
+                        break;
+                case USER_PROCESS: {
+                        int show;
+
+                        if (!ut.ut_line[0]) {
+                                break;
+                        }
+                        /* find_entry */
+                        show = 1;
+                        {
+                                llist_t *el, *next;
+                                for (el = zlist; el; el = next) {
+                                        struct utmp *up = (struct utmp *)el->data;
+                                        next = el->link;
+                                        if (strncmp(up->ut_line, ut.ut_line, UT_LINESIZE) == 0) {
+                                                if (show) {
+                                                        show_entry(&ut, NORMAL, up->ut_time);
+                                                        show = 0;
+                                                }
+                                                llist_unlink(&zlist, el);
+                                                free(el->data);
+                                                free(el);
+                                        }
+                                }
+                        }
+
+                        if (show) {
+                                int state = boot_down;
+
+                                if (boot_time == 0) {
+                                        state = LOGGED;
+                                        /* Check if the process is alive */
+                                        if ((ut.ut_pid > 0)
+                                         && (kill(ut.ut_pid, 0) != 0)
+                                         && (errno == ESRCH)) {
+                                                state = GONE;
+                                        }
+                                }
+                                show_entry(&ut, state, boot_time);
+                        }
+                        /* add_entry */
+                        llist_add_to(&zlist, memcpy(xmalloc(sizeof(ut)), &ut, sizeof(ut)));
+                        break;
+                }
+                }
+
+                if (going_down) {
+                        boot_time = ut.ut_time;
+                        llist_free(zlist, free);
+                        zlist = NULL;
+                        going_down = 0;
+                }
+        }
+
+        if (ENABLE_FEATURE_CLEAN_UP) {
+                llist_free(zlist, free);
+        }
+
+ exit:
+        printf("\nwtmp begins %s", ctime(&start_time));
+
+        if (ENABLE_FEATURE_CLEAN_UP)
+                close(file);
+        fflush_stdout_and_exit(EXIT_SUCCESS);
+}