/*
 *  Top users/processes display for Unix
 *  Version 3
 *
 *  This program may be freely redistributed,
 *  but this entire comment MUST remain intact.
 *
 *  Copyright (c) 1984, 1989, William LeFebvre, Rice University
 *  Copyright (c) 1989, 1990, 1992, William LeFebvre, Northwestern University
 */

/*
 *  This file contains the routines that implement some of the interactive
 *  mode commands.  Note that some of the commands are implemented in-line
 *  in "main".  This is necessary because they change the global state of
 *  "top" (i.e.:  changing the number of processes to display).
 */

#include <sys/resource.h>
#include <sys/signal.h>

#include <ctype.h>
#include <errno.h>
#include <signal.h>
#include <stdbool.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>

#include "commands.h"
#include "top.h"
#include "machine.h"

static int err_compar(const void *p1, const void *p2);

struct errs             /* structure for a system-call error */
{
    int  errnum;        /* value of errno (that is, the actual error) */
    char *arg;          /* argument that caused the error */
};

static char *err_string(void);
static int str_adderr(char *str, int len, int err);
static int str_addarg(char *str, int len, char *arg, bool first);

/*
 *  show_help() - display the help screen; invoked in response to
 *              either 'h' or '?'.
 */

const struct command all_commands[] =
{
        {' ', "update the display", false, CMD_update},
        {'/', "filter on command name (+ selects all commands)", false, CMD_grep},
        {'a', "toggle the display of process titles", false, CMD_showargs},
        {'C', "toggle the display of raw or weighted CPU percentage", false, CMD_wcputog},
        {'d', "change number of displays to show", false, CMD_displays},
        {'e', "list errors generated by last \"kill\" or \"renice\" command", false, CMD_errors},
        {'H', "toggle the display of threads", false, CMD_thrtog},
        {'h', "show this help text", true, CMD_help},
        {'?', NULL, true, CMD_help},
        {'i', "toggle the display of idle processes", false, CMD_idletog},
        {'I', NULL, false, CMD_idletog},
        {'J', "display processes for only one jail (+ selects all jails)", false, CMD_jail},
        {'j', "toggle the display of jail ID", false, CMD_jidtog},
        {'k', "kill processes; send a signal to a list of processes", false, CMD_kill},
        {'m', "toggle the display between 'cpu' and 'io' modes", false, CMD_viewtog},
        {'n', "change number of processes to display", false, CMD_number},
        {'#', NULL, false, CMD_number},
        {'o', "specify the sort order", false, CMD_order},
        {'P', "toggle the display of per-CPU statistics", false, CMD_pcputog},
        {'p', "display one process (+ selects all processes)", false, CMD_pid},
        {'q', "quit" , true, CMD_quit},
        {'r', "renice a process", false, CMD_renice},
        {'S', "toggle the display of system processes", false, CMD_viewsys},
        {'s', "change number of seconds to delay between updates", false, CMD_delay},
        {'T', "toggle the display of thread IDs", false, CMD_toggletid},
        {'t', "toggle the display of this process", false, CMD_selftog},
        {'u', "display processes for only one user (+ selects all users)", false, CMD_user},
        {'w', "toggle the display of swap use for each process", false, CMD_swaptog},
        {'z', "toggle the display of the system idle process", false, CMD_kidletog},
        {0, NULL, true, CMD_NONE}
};

void
show_help(void)
{
        const struct command *curcmd, *nextcmd;
        char keys[8] = "";
        _Static_assert(sizeof(keys) >= sizeof("a or b"), "keys right size");

    printf("Top version FreeBSD, %s\n", copyright);
        curcmd = all_commands;
        while (curcmd->c != 0) {
                if (overstrike && !curcmd->available_to_dumb) {
                        ++curcmd;
                        continue;
                }
                if (curcmd->desc == NULL) {
                        /* we already printed this */
                        ++curcmd;
                        continue;
                }
                nextcmd = curcmd + 1;
                if (nextcmd->desc == NULL && nextcmd->c != '\0') {
                        sprintf(keys, "%c or %c", curcmd->c, nextcmd->c);
                } else if (curcmd->c == ' '){
                        /* special case space rather than introducing a "display string" to
                         * the struct */
                        sprintf(keys, "space");
                } else {
                        sprintf(keys, "%c", curcmd->c);
                }
                printf("%s\t- %s\n", keys, curcmd->desc);
                ++curcmd;
        }
    if (overstrike)
    {
                fputs("\
                                Other commands are also available, but this terminal is not\n\
                                sophisticated enough to handle those commands gracefully.\n", stdout);
    }
}

/*
 *  Utility routines that help with some of the commands.
 */

static char *
next_field(char *str)
{
    if ((str = strchr(str, ' ')) == NULL)
    {
        return(NULL);
    }
    *str = '\0';
    while (*++str == ' ') /* loop */;

    /* if there is nothing left of the string, return NULL */
    /* This fix is dedicated to Greg Earle */
    return(*str == '\0' ? NULL : str);
}

static int
scanint(char *str, int *intp)
{
    int val = 0;
    char ch;

    /* if there is nothing left of the string, flag it as an error */
    /* This fix is dedicated to Greg Earle */
    if (*str == '\0')
    {
        return(-1);
    }

    while ((ch = *str++) != '\0')
    {
        if (isdigit(ch))
        {
            val = val * 10 + (ch - '0');
        }
        else if (isspace(ch))
        {
            break;
        }
        else
        {
            return(-1);
        }
    }
    *intp = val;
    return(0);
}

/*
 *  Some of the commands make system calls that could generate errors.
 *  These errors are collected up in an array of structures for later
 *  contemplation and display.  Such routines return a string containing an
 *  error message, or NULL if no errors occurred.  The next few routines are
 *  for manipulating and displaying these errors.  We need an upper limit on
 *  the number of errors, so we arbitrarily choose 20.
 */

#define ERRMAX 20

static struct errs errs[ERRMAX];
static int errcnt;
static char err_toomany[] = " too many errors occurred";
static char err_listem[] =
        " Many errors occurred.  Press `e' to display the list of errors.";

/* These macros get used to reset and log the errors */
#define ERR_RESET   errcnt = 0
#define ERROR(p, e) if (errcnt >= ERRMAX) \
                    { \
                        return(err_toomany); \
                    } \
                    else \
                    { \
                        errs[errcnt].arg = (p); \
                        errs[errcnt++].errnum = (e); \
                    }

/*
 *  err_string() - return an appropriate error string.  This is what the
 *      command will return for displaying.  If no errors were logged, then
 *      return NULL.  The maximum length of the error string is defined by
 *      "STRMAX".
 */

#define STRMAX 80

char *
err_string(void)
{
    struct errs *errp;
    int cnt = 0;
    bool first = true;
    int currerr = -1;
    int stringlen;              /* characters still available in "string" */
    static char string[STRMAX];

    /* if there are no errors, return NULL */
    if (errcnt == 0)
    {
        return(NULL);
    }

    /* sort the errors */
    qsort((char *)errs, errcnt, sizeof(struct errs), err_compar);

    /* need a space at the front of the error string */
    string[0] = ' ';
    string[1] = '\0';
    stringlen = STRMAX - 2;

    /* loop thru the sorted list, building an error string */
    while (cnt < errcnt)
    {
        errp = &(errs[cnt++]);
        if (errp->errnum != currerr)
        {
            if (currerr >= 0)
            {
                if ((stringlen = str_adderr(string, stringlen, currerr)) < 2)
                {
                    return(err_listem);
                }
                strcat(string, "; ");     /* we know there's more */
            }
            currerr = errp->errnum;
            first = true;
        }
        if ((stringlen = str_addarg(string, stringlen, errp->arg, first)) ==0)
        {
            return(err_listem);
        }
        first = false;
    }

    /* add final message */
    stringlen = str_adderr(string, stringlen, currerr);

    /* return the error string */
    return(stringlen == 0 ? err_listem : string);
}

/*
 *  str_adderr(str, len, err) - add an explanation of error "err" to
 *      the string "str".
 */

static int
str_adderr(char *str, int len, int err)
{
    const char *msg;
    int msglen;

    msg = err == 0 ? "Not a number" : strerror(err);
    msglen = strlen(msg) + 2;
    if (len <= msglen)
    {
        return(0);
    }
    strcat(str, ": ");
    strcat(str, msg);
    return(len - msglen);
}

/*
 *  str_addarg(str, len, arg, first) - add the string argument "arg" to
 *      the string "str".  This is the first in the group when "first"
 *      is set (indicating that a comma should NOT be added to the front).
 */

static int
str_addarg(char str[], int len, char arg[], bool first)
{
    int arglen;

    arglen = strlen(arg);
    if (!first)
    {
        arglen += 2;
    }
    if (len <= arglen)
    {
        return(0);
    }
    if (!first)
    {
        strcat(str, ", ");
    }
    strcat(str, arg);
    return(len - arglen);
}

/*
 *  err_compar(p1, p2) - comparison routine used by "qsort"
 *      for sorting errors.
 */

static int
err_compar(const void *p1, const void *p2)
{
    int result;
    const struct errs * const g1 = (const struct errs * const)p1;
    const struct errs * const g2 = (const struct errs * const)p2;



    if ((result = g1->errnum - g2->errnum) == 0)
    {
        return(strcmp(g1->arg, g2->arg));
    }
    return(result);
}

/*
 *  error_count() - return the number of errors currently logged.
 */

int
error_count(void)
{
    return(errcnt);
}

/*
 *  show_errors() - display on stdout the current log of errors.
 */

void
show_errors(void)
{
    int cnt = 0;
    struct errs *errp = errs;

    printf("%d error%s:\n\n", errcnt, errcnt == 1 ? "" : "s");
    while (cnt++ < errcnt)
    {
        printf("%5s: %s\n", errp->arg,
            errp->errnum == 0 ? "Not a number" : strerror(errp->errnum));
        errp++;
    }
}

static const char no_proc_specified[] = " no processes specified";
static const char invalid_signal_number[] = " invalid_signal_number";
static const char bad_signal_name[] = " bad signal name";
static const char bad_pri_value[] = " bad priority value";

static int
signame_to_signum(const char * sig)
{
        int n;

        if (strncasecmp(sig, "SIG", 3) == 0)
                sig += 3;
        for (n = 1; n < sys_nsig; n++) {
            if (!strcasecmp(sys_signame[n], sig))
                return (n);
        }
        return (-1);
}

/*
 *  kill_procs(str) - send signals to processes, much like the "kill"
 *              command does; invoked in response to 'k'.
 */

const char *
kill_procs(char *str)
{
    char *nptr;
    int signum = SIGTERM;       /* default */
    int procnum;

    /* reset error array */
    ERR_RESET;

    /* skip over leading white space */
    while (isspace(*str)) str++;

    if (str[0] == '-')
    {
        /* explicit signal specified */
        if ((nptr = next_field(str)) == NULL)
        {
            return(no_proc_specified);
        }

        if (isdigit(str[1]))
        {
            scanint(str + 1, &signum);
            if (signum <= 0 || signum >= NSIG)
            {
                return(invalid_signal_number);
            }
        }
        else
        {
                signum = signame_to_signum(str + 1);

            /* was it ever found */
            if (signum == -1 )
            {
                        return(bad_signal_name);
            }
        }
        /* put the new pointer in place */
        str = nptr;
    }

    /* loop thru the string, killing processes */
    do
    {
        if (scanint(str, &procnum) == -1)
        {
            ERROR(str, 0);
        }
        else
        {
            /* go in for the kill */
            if (kill(procnum, signum) == -1)
            {
                /* chalk up an error */
                ERROR(str, errno);
            }
        }
    } while ((str = next_field(str)) != NULL);

    /* return appropriate error string */
    return(err_string());
}

/*
 *  renice_procs(str) - change the "nice" of processes, much like the
 *              "renice" command does; invoked in response to 'r'.
 */

const char *
renice_procs(char *str)
{
    char negate;
    int prio;
    int procnum;

    ERR_RESET;

    /* allow for negative priority values */
    if ((negate = (*str == '-')) != 0)
    {
        /* move past the minus sign */
        str++;
    }

    /* use procnum as a temporary holding place and get the number */
    procnum = scanint(str, &prio);

    /* negate if necessary */
    if (negate)
    {
        prio = -prio;
    }

    /* check for validity */
    if (procnum == -1 || prio < PRIO_MIN || prio > PRIO_MAX)
    {
        return(bad_pri_value);
    }

    /* move to the first process number */
    if ((str = next_field(str)) == NULL)
    {
        return(no_proc_specified);
    }

    /* loop thru the process numbers, renicing each one */
    do
    {
        if (scanint(str, &procnum) == -1)
        {
            ERROR(str, 0);
        }

        if (setpriority(PRIO_PROCESS, procnum, prio) == -1)
        {
            ERROR(str, errno);
        }
    } while ((str = next_field(str)) != NULL);

    /* return appropriate error string */
    return(err_string());
}