/** \file builtin_ulimit.c Functions defining the ulimit builtin

Functions used for implementing the ulimit builtin.

*/
#include <wchar.h>
#include <sys/resource.h>
#include <errno.h>

#include "fallback.h"  // IWYU pragma: keep
#include "util.h"
#include "builtin.h"
#include "common.h"
#include "wgetopt.h"
#include "io.h"
#include "wutil.h"  // IWYU pragma: keep

class parser_t;

/**
   Struct describing a resource limit
*/
struct resource_t
{
    /**
       Resource id
     */
    int resource;
    /**
       Description of resource
    */
    const wchar_t *desc;
    /**
       Switch used on commandline to specify resource
    */
    wchar_t switch_char;
    /**
       The implicit multiplier used when setting getting values
    */
    int multiplier;
}
;

/**
   Array of resource_t structs, describing all known resource types.
*/
static const struct resource_t resource_arr[] =
{
    {
        RLIMIT_CORE, L"Maximum size of core files created", L'c', 1024
    }
    ,
    {
        RLIMIT_DATA, L"Maximum size of a process’s data segment", L'd', 1024
    }
    ,
    {
        RLIMIT_FSIZE, L"Maximum size of files created by the shell", L'f', 1024
    }
    ,
#ifdef RLIMIT_MEMLOCK
    {
        RLIMIT_MEMLOCK, L"Maximum size that may be locked into memory", L'l', 1024
    }
    ,
#endif
#ifdef RLIMIT_RSS
    {
        RLIMIT_RSS, L"Maximum resident set size", L'm', 1024
    }
    ,
#endif
    {
        RLIMIT_NOFILE, L"Maximum number of open file descriptors", L'n', 1
    }
    ,
    {
        RLIMIT_STACK, L"Maximum stack size", L's', 1024
    }
    ,
    {
        RLIMIT_CPU, L"Maximum amount of cpu time in seconds", L't', 1
    }
    ,
#ifdef RLIMIT_NPROC
    {
        RLIMIT_NPROC, L"Maximum number of processes available to a single user", L'u', 1
    }
    ,
#endif
#ifdef RLIMIT_AS
    {
        RLIMIT_AS, L"Maximum amount of virtual memory available to the shell", L'v', 1024
    }
    ,
#endif
    {
        0, 0, 0, 0
    }
}
;

/**
   Get the implicit multiplication factor for the specified resource limit
*/
static int get_multiplier(int what)
{
    int i;

    for (i=0; resource_arr[i].desc; i++)
    {
        if (resource_arr[i].resource == what)
        {
            return resource_arr[i].multiplier;
        }
    }
    return -1;
}

/**
   Return the value for the specified resource limit. This function
   does _not_ multiply the limit value by the multiplier constant used
   by the commandline ulimit.
*/
static rlim_t get(int resource, int hard)
{
    struct rlimit ls;

    getrlimit(resource, &ls);

    return hard ? ls.rlim_max:ls.rlim_cur;
}

/**
   Print the value of the specified resource limit
*/
static void print(int resource, int hard, io_streams_t &streams)
{
    rlim_t l = get(resource, hard);

    if (l == RLIM_INFINITY)
        streams.out.append(L"unlimited\n");
    else
        streams.out.append_format( L"%d\n", l / get_multiplier(resource));

}

/**
   Print values of all resource limits
*/
static void print_all(int hard, io_streams_t &streams)
{
    int i;
    int w=0;

    for (i=0; resource_arr[i].desc; i++)
    {
        w=maxi(w, fish_wcswidth(resource_arr[i].desc));
    }

    for (i=0; resource_arr[i].desc; i++)
    {
        struct rlimit ls;
        rlim_t l;
        getrlimit(resource_arr[i].resource, &ls);
        l = hard ? ls.rlim_max:ls.rlim_cur;

        const wchar_t *unit = ((resource_arr[i].resource==RLIMIT_CPU)?L"(seconds, ":(get_multiplier(resource_arr[i].resource)==1?L"(":L"(kB, "));

        streams.out.append_format(
                      L"%-*ls %10ls-%lc) ",
                      w,
                      resource_arr[i].desc,
                      unit,
                      resource_arr[i].switch_char);

        if (l == RLIM_INFINITY)
        {
            streams.out.append(L"unlimited\n");
        }
        else
        {
            streams.out.append_format( L"%d\n", l/get_multiplier(resource_arr[i].resource));
        }
    }

}

/**
   Returns the description for the specified resource limit
*/
static const wchar_t *get_desc(int what)
{
    int i;

    for (i=0; resource_arr[i].desc; i++)
    {
        if (resource_arr[i].resource == what)
        {
            return resource_arr[i].desc;
        }
    }
    return L"Not a resource";
}

/**
   Set the new value of the specified resource limit. This function
   does _not_ multiply the limit value by the multiplier constant used
   by the commandline ulimit.
*/
static int set(int resource, int hard, int soft, rlim_t value, io_streams_t &streams)
{
    struct rlimit ls;
    getrlimit(resource, &ls);

    if (hard)
    {
        ls.rlim_max = value;
    }

    if (soft)
    {
        ls.rlim_cur = value;

        /*
          Do not attempt to set the soft limit higher than the hard limit
        */
        if ((value == RLIM_INFINITY && ls.rlim_max != RLIM_INFINITY) ||
                (value != RLIM_INFINITY && ls.rlim_max != RLIM_INFINITY && value > ls.rlim_max))
        {
            ls.rlim_cur = ls.rlim_max;
        }
    }

    if (setrlimit(resource, &ls))
    {
        if (errno == EPERM)
            streams.err.append_format(L"ulimit: Permission denied when changing resource of type '%ls'\n", get_desc(resource));
        else
            builtin_wperror(L"ulimit", streams);
        return 1;
    }
    return 0;
}

/**
   The ulimit builtin, used for setting resource limits. Defined in
   builtin_ulimit.c.
*/
static int builtin_ulimit(parser_t &parser, io_streams_t &streams, wchar_t **argv)
{
    wgetopter_t w;
    int hard=0;
    int soft=0;

    int what = RLIMIT_FSIZE;
    int report_all = 0;

    int argc = builtin_count_args(argv);

    w.woptind=0;

    while (1)
    {
        static const struct woption
                long_options[] =
        {
            {
                L"all", no_argument, 0, 'a'
            }
            ,
            {
                L"hard", no_argument, 0, 'H'
            }
            ,
            {
                L"soft", no_argument, 0, 'S'
            }
            ,
            {
                L"core-size", no_argument, 0, 'c'
            }
            ,
            {
                L"data-size", no_argument, 0, 'd'
            }
            ,
            {
                L"file-size", no_argument, 0, 'f'
            }
            ,
            {
                L"lock-size", no_argument, 0, 'l'
            }
            ,
            {
                L"resident-set-size", no_argument, 0, 'm'
            }
            ,
            {
                L"file-descriptor-count", no_argument, 0, 'n'
            }
            ,
            {
                L"stack-size", no_argument, 0, 's'
            }
            ,
            {
                L"cpu-time", no_argument, 0, 't'
            }
            ,
            {
                L"process-count", no_argument, 0, 'u'
            }
            ,
            {
                L"virtual-memory-size", no_argument, 0, 'v'
            }
            ,
            {
                L"help", no_argument, 0, 'h'
            }
            ,
            {
                0, 0, 0, 0
            }
        }
        ;


        int opt_index = 0;

        int opt = w.wgetopt_long(argc,
                                 argv,
                                 L"aHScdflmnstuvh",
                                 long_options,
                                 &opt_index);
        if (opt == -1)
            break;

        switch (opt)
        {
            case 0:
                if (long_options[opt_index].flag != 0)
                    break;
                streams.err.append_format(BUILTIN_ERR_UNKNOWN,
                              argv[0],
                              long_options[opt_index].name);
                builtin_print_help(parser, streams, argv[0], streams.err);

                return 1;

            case L'a':
                report_all=1;
                break;

            case L'H':
                hard=1;
                break;

            case L'S':
                soft=1;
                break;

            case L'c':
                what=RLIMIT_CORE;
                break;

            case L'd':
                what=RLIMIT_DATA;
                break;

            case L'f':
                what=RLIMIT_FSIZE;
                break;
#ifdef RLIMIT_MEMLOCK
            case L'l':
                what=RLIMIT_MEMLOCK;
                break;
#endif

#ifdef RLIMIT_RSS
            case L'm':
                what=RLIMIT_RSS;
                break;
#endif

            case L'n':
                what=RLIMIT_NOFILE;
                break;

            case L's':
                what=RLIMIT_STACK;
                break;

            case L't':
                what=RLIMIT_CPU;
                break;

#ifdef RLIMIT_NPROC
            case L'u':
                what=RLIMIT_NPROC;
                break;
#endif

#ifdef RLIMIT_AS
            case L'v':
                what=RLIMIT_AS;
                break;
#endif

            case L'h':
                builtin_print_help(parser, streams, argv[0], streams.out);
                return 0;

            case L'?':
                builtin_unknown_option(parser, streams, argv[0], argv[w.woptind-1]);
                return 1;
        }
    }

    if (report_all)
    {
        if (argc - w.woptind == 0)
        {
            print_all(hard, streams);
        }
        else
        {
            streams.err.append(argv[0]);
            streams.err.append(L": Too many arguments\n");
            builtin_print_help(parser, streams, argv[0], streams.err);
            return 1;
        }

        return 0;
    }

    switch (argc - w.woptind)
    {
        case 0:
        {
            /*
              Show current limit value
            */
            print(what, hard, streams);
            break;
        }

        case 1:
        {
            /*
              Change current limit value
            */
            rlim_t new_limit;
            wchar_t *end;

            /*
              Set both hard and soft limits if nothing else was specified
            */
            if (!(hard+soft))
            {
                hard=soft=1;
            }

            if (wcscasecmp(argv[w.woptind], L"unlimited")==0)
            {
                new_limit = RLIM_INFINITY;
            }
            else if (wcscasecmp(argv[w.woptind], L"hard")==0)
            {
                new_limit = get(what, 1);
            }
            else if (wcscasecmp(argv[w.woptind], L"soft")==0)
            {
                new_limit = get(what, soft);
            }
            else
            {
                errno=0;
                new_limit = wcstol(argv[w.woptind], &end, 10);
                if (errno || *end)
                {
                    streams.err.append_format(L"%ls: Invalid limit '%ls'\n",
                                  argv[0],
                                  argv[w.woptind]);
                    builtin_print_help(parser, streams, argv[0], streams.err);
                    return 1;
                }
                new_limit *= get_multiplier(what);
            }

            return set(what, hard, soft, new_limit, streams);
        }

        default:
        {
            streams.err.append(argv[0]);
            streams.err.append(L": Too many arguments\n");
            builtin_print_help(parser, streams, argv[0], streams.err);
            return 1;
        }

    }
    return 0;
}