/*
 * Copyright (C) 2008 The Android Open Source Project
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *  * Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *  * Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */
#include <unistd.h>
#include <sys/sysconf.h>
#include <limits.h>
#include <bionic_tls.h>
#include <asm/page.h>
#include <stdio.h>  /* for FOPEN_MAX */
#include <errno.h>
#include <fcntl.h>
#include <string.h>
#include <ctype.h>

/* seems to be the default on Linux, per the GLibc sources and my own digging */

#define  SYSTEM_CLK_TCK         100
#define  SYSTEM_IOV_MAX         1024
#define  SYSTEM_DELAYTIMER_MAX  2147483647
#define  SYSTEM_MQ_OPEN_MAX     8
#define  SYSTEM_MQ_PRIO_MAX     32768
#define  SYSTEM_SEM_NSEMS_MAX   256
#define  SYSTEM_SEM_VALUE_MAX   (2147483647)
#define  SYSTEM_SIGQUEUE_MAX    32
#define  SYSTEM_TIMER_MAX       32
#define  SYSTEM_LOGIN_NAME_MAX  256
#define  SYSTEM_TTY_NAME_MAX    32

/* the following depends on our implementation */
#define  SYSTEM_ATEXIT_MAX          65536    /* our implementation is unlimited */
#define  SYSTEM_THREAD_KEYS_MAX     BIONIC_TLS_SLOTS
#define  SYSTEM_THREAD_STACK_MIN    32768    /* lower values may be possible, but be conservative */
#define  SYSTEM_THREAD_THREADS_MAX  2048     /* really unlimited */

#define  SYSTEM_2_C_BIND     _POSIX_VERSION  /* Posix C binding version */
#define  SYSTEM_2_C_VER      _POSIX2_C_VERSION
#define  SYSTEM_2_C_DEV      -1       /* Posix C development tools unsupported on the device */
#define  SYSTEM_2_FORT_DEV   -1       /* Fortran development unsupported */
#define  SYSTEM_2_FORT_RUN   -1       /* Fortran runtime unsupported */
#define  SYSTEM_2_SW_DEV     -1       /* posix software dev utilities unsupported */
#define  SYSTEM_2_LOCALEDEF  -1       /* localdef() unimplemented */
#define  SYSTEM_2_UPE        -1       /* No UPE for you ! (User Portability Utilities) */
#define  SYSTEM_2_VERSION    -1       /* No posix command-line tools */

static int  __get_nproc_conf(void);
static int  __get_nproc_onln(void);
static int  __get_phys_pages(void);
static int  __get_avphys_pages(void);

int
sysconf( int  name )
{
    switch (name) {
#ifdef _POSIX_ARG_MAX
    case _SC_ARG_MAX:           return _POSIX_ARG_MAX;
#endif
#ifdef _POSIX2_BC_BASE_MAX
    case _SC_BC_BASE_MAX:       return _POSIX2_BC_BASE_MAX;
#endif
#ifdef _POSIX2_BC_DIM_MAX
    case _SC_BC_DIM_MAX:        return _POSIX2_BC_DIM_MAX;
#endif
#ifdef _POSIX2_BC_SCALE_MAX
    case _SC_BC_SCALE_MAX:      return _POSIX2_BC_SCALE_MAX;
#endif
#ifdef _POSIX2_BC_STRING_MAX
    case _SC_BC_STRING_MAX:     return _POSIX2_BC_STRING_MAX;
#endif
    case _SC_CHILD_MAX:         return CHILD_MAX;
    case _SC_CLK_TCK:           return SYSTEM_CLK_TCK;
#ifdef _POSIX2_COLL_WEIGHTS_MASK
    case _SC_COLL_WEIGHTS_MAX:  return _POSIX2_COLL_WEIGHTS_MASK;
#endif
#ifdef _POSIX2_EXPR_NEST_MAX
    case _SC_EXPR_NEXT_MASK:    return _POSIX2_EXPR_NEST_MAX;
#endif
#ifdef _POSIX2_LINE_MAX
    case _SC_LINE_MAX:          return _POSIX2_LINE_MAX;
#endif
    case _SC_NGROUPS_MAX:       return NGROUPS_MAX;
    case _SC_OPEN_MAX:          return OPEN_MAX;
    //case _SC_PASS_MAX:          return PASS_MAX;
    case _SC_2_C_BIND:          return SYSTEM_2_C_BIND;
    case _SC_2_C_DEV:           return SYSTEM_2_C_DEV;
    case _SC_2_C_VERSION:       return SYSTEM_2_C_VER;
    //case _SC_2_CHAR_TERM:         return ;
    case _SC_2_FORT_DEV:        return SYSTEM_2_FORT_DEV;
    case _SC_2_FORT_RUN:        return SYSTEM_2_FORT_RUN;
    case _SC_2_LOCALEDEF:       return SYSTEM_2_LOCALEDEF;
    case _SC_2_SW_DEV:          return SYSTEM_2_SW_DEV;
    case _SC_2_UPE:             return SYSTEM_2_UPE;
    case _SC_2_VERSION:         return SYSTEM_2_VERSION;
#ifdef _POSIX_JOB_CONTROL
    case _SC_JOB_CONTROL:       return _POSIX_JOB_CONTROL;
#endif
#ifdef _POSIX_SAVED_IDS
    case _SC_SAVED_IDS:         return _POSIX_SAVED_IDS;
#endif
#ifdef _POSIX_VERSION
    case _SC_VERSION:           return _POSIX_VERSION;
#endif
    //case _SC_RE_DUP_<AX:        return ;
    case _SC_STREAM_MAX:        return FOPEN_MAX;
    //case _SC_TZNAME_MAX:        return ;
#if _XOPEN_CRYPT
    case _SC_XOPEN_CRYPT:       return _XOPEN_CRYPT;
#endif
#ifdef _XOPEN_ENH_I18N
    case _SC_XOPEN_ENH_I18N:    return _XOPEN_ENH_I18N;
#endif
#ifdef _XOPEN_SHM
    case _SC_XOPEN_SHM:         return _XOPEN_SHM;
#endif
#ifdef _XOPEN_VERSION
    case _SC_XOPEN_VERSION:     return _XOPEN_VERSION;
#endif
#ifdef _XOPEN_XCU_VERSION
    case _SC_XOPEN_XCU_VERSION: return _XOPEN_XCU_VERSION;
#endif
#ifdef _XOPEN_REALTIME
    case _SC_XOPEN_REALTIME:    return _XOPEN_REALTIME;
#endif
#ifdef _XOPEN_REALTIME_THREADS
    case _SC_XOPEN_REALTIME_THREADS: return _XOPEN_REALTIME_THREADS;
#endif
#ifdef _XOPEN_LEGACY
    case _SC_XOPEN_LEGACY:      return _XOPEN_LEGACY;
#endif
    case _SC_ATEXIT_MAX:        return SYSTEM_ATEXIT_MAX;
    case _SC_IOV_MAX:           return SYSTEM_IOV_MAX;
    case _SC_PAGESIZE:          return PAGE_SIZE;
    case _SC_PAGE_SIZE:         return PAGE_SIZE;
#ifdef _XOPEN_UNIX
    case _SC_XOPEN_UNIX:        return _XOPEN_UNIX;
#endif

    // XXX: TODO: XBS5 nonsense

#ifdef AIO_LISTIO_MAX
    case _SC_AIO_LISTIO_MAX:       return AIO_LISTIO_MAX;
#endif
#ifdef AIO_MAX
    case _SC_AIO_MAX:              return AIO_MAX;
#endif
#ifdef AIO_PRIO_DELTA_MAX
    case _SC_AIO_PRIO_DELTA_MAX:   return AIO_PRIO_DELTA_MAX;
#endif
    case _SC_DELAYTIMER_MAX:    return SYSTEM_DELAYTIMER_MAX;
    case _SC_MQ_OPEN_MAX:       return SYSTEM_MQ_OPEN_MAX;
    case _SC_MQ_PRIO_MAX:       return SYSTEM_MQ_PRIO_MAX;
    case _SC_RTSIG_MAX:         return RTSIG_MAX;
    case _SC_SEM_NSEMS_MAX:     return SYSTEM_SEM_NSEMS_MAX;
    case _SC_SEM_VALUE_MAX:     return SYSTEM_SEM_VALUE_MAX;
    case _SC_SIGQUEUE_MAX:      return SYSTEM_SIGQUEUE_MAX;
    case _SC_TIMER_MAX:         return SYSTEM_TIMER_MAX;
#ifdef _POSIX_ASYNCHRONOUS_IO
    case _SC_ASYNCHRONOUS_IO:   return _POSIX_ASYNCHRONOUS_IO;
#endif
#ifdef _POSIX_FSYNC
    case _SC_FSYNC:             return _POSIX_FSYNC;
#endif
#ifdef _POSIX_MAPPED_FILES
    case _SC_MAPPED_FILES:      return _POSIX_MAPPED_FILES;
#endif
#ifdef _POSIX_MEMLOCK
    case _SC_MEMLOCK:           return _POSIX_MEMLOCK;
#endif
#ifdef _POSIX_MEMLOCK_RANGE
    case _SC_MEMLOCK_RANGE:     return _POSIX_MEMLOCK_RANGE
#endif
#ifdef _POSIX_MEMORY_PROTECTION
    case _SC_MEMORY_PROTECTION: return _POSIX_MEMORY_PROTECTION;
#endif
#ifdef _POSIX_MESSAGE_PASSING
    case _SC_MESSAGE_PASSING:   return _POSIX_MESSAGE_PASSING;
#endif
#ifdef _POSIX_PRIORITIZED_IO
    case _SC_PRIORITIZED_IO:    return _POSIX_PRIORITIZED_IO;
#endif
#ifdef _POSIX_PRIORITY_SCHEDULING
    case _SC_PRIORITY_SCHEDULING:  return _POSIX_PRIORITY_SCHEDULING;
#endif
#ifdef _POSIX_REALTIME_SIGNALS
    case _SC_REALTIME_SIGNALS:  return _POSIX_REALTIME_SIGNALS;
#endif
#ifdef _POSIX_SEMAPHORES
    case _SC_SEMAPHORES:        return _POSIX_SEMAPHORES;
#endif
#ifdef _POSIX_SHARED_MEMORY_OBJECTS
    case _SC_SHARED_MEMORY_OBJECTS:  return _POSIX_SHARED_MEMORY_OBJECTS;
#endif
#ifdef _POSIX_SYNCHRONIZED_IO
    case _SC_SYNCHRONIZED_IO:   return _POSIX_SYNCHRONIZED_IO;
#endif
#ifdef _POSIX_TIMERS
    case _SC_TIMERS:            return _POSIX_TIMERS;
#endif

    // GETGR_R_SIZE_MAX ?
    // GETPW_R_SIZE_MAX ?

    case _SC_LOGIN_NAME_MAX:    return SYSTEM_LOGIN_NAME_MAX;
#ifdef _POSIX_THREAD_DESTRUCTOR_ITERATIONS
    case _SC_THREAD_DESTRUCTOR_ITERATIONS:  return _POSIX_THREAD_DESTRUCTOR_ITERATIONS;
#endif
    case _SC_THREAD_KEYS_MAX:     return SYSTEM_THREAD_KEYS_MAX;
    case _SC_THREAD_STACK_MIN:    return SYSTEM_THREAD_STACK_MIN;
    case _SC_THREAD_THREADS_MAX:  return SYSTEM_THREAD_THREADS_MAX;
    case _SC_TTY_NAME_MAX:        return SYSTEM_TTY_NAME_MAX;
#ifdef _POSIX_THREADS
    case _SC_THREADS:             return _POSIX_THREADS;
#endif
#ifdef _POSIX_THREAD_ATTR_STACKADDR
    case _SC_THREAD_ATTR_STACKADDR:   return _POSIX_THREAD_ATTR_STACKADDR;
#endif
#ifdef _POSIX_THREAD_ATTR_STACKSIZE
    case _SC_THREAD_ATTR_STACKSIZE:   return _POSIX_THREAD_ATTR_STACKSIZE;
#endif
#ifdef _POSIX_THREAD_PRIORITY_SCHEDULING
    case _SC_THREAD_PRIORITY_SCHEDULING:  return _POSIX_THREAD_PRIORITY_SCHEDULING;
#endif
#ifdef _POSIX_THREAD_PRIO_INHERIT
    case _SC_THREAD_PRIO_INHERIT:         return _POSIX_THREAD_PRIO_INHERIT;
#endif
#ifdef _POSIX_THREAD_PRIO_PROTECT
    case _SC_THREAD_PRIO_PROTECT: return _POSIX_THREAD_PRIO_PROTECT;
#endif
#ifdef _POSIX_THREAD_SAFE_FUNCTIONS
    case _SC_THREAD_SAFE_FUNCTIONS:  return _POSIX_THREAD_SAFE_FUNCTIONS
#endif


    case _SC_NPROCESSORS_CONF:  return __get_nproc_conf();
    case _SC_NPROCESSORS_ONLN:  return __get_nproc_onln();
    case _SC_PHYS_PAGES:        return __get_phys_pages();
    case _SC_AVPHYS_PAGES:      return __get_avphys_pages();

    default:
       /* Posix says EINVAL is the only error that shall be returned,
        * but GLibc uses ENOSYS */
        errno = ENOSYS;
        return -1;
    }
}


typedef struct {
    int   rpos;
    int   len;
    int   overflow;
    int   fd;
    int   in_len;
    int   in_pos;
    char  buff[128];
    char  input[128];
} LineParser;

static int
line_parser_init( LineParser*  p, const char*  path )
{
    p->rpos     = 0;
    p->len      = (int)sizeof(p->buff);
    p->overflow = 0;

    p->in_len   = 0;
    p->in_pos   = 0;
    p->fd       = open( path, O_RDONLY );

    return p->fd;
}


static int
line_parser_addc( LineParser*  p, int  c )
{
    if (p->overflow) {
        p->overflow = (c == '\n');
        return 0;
    }
    if (p->rpos >= p->len) {
        p->overflow = 1;
        return 0;
    }
    if (c == '\n') {
        p->buff[p->rpos] = 0;
        p->rpos = 0;
        return 1;
    }
    p->buff[p->rpos++] = (char) c;
    return 0;
}

static int
line_parser_getc( LineParser*  p )
{
    if (p->in_pos >= p->in_len) {
        int  ret;

        p->in_len = p->in_pos = 0;
        do {
            ret = read(p->fd, p->input, sizeof(p->input));
        } while (ret < 0 && errno == EINTR);

        if (ret <= 0)
            return -1;

        p->in_len = ret;
    }
    return p->input[ p->in_pos++ ];
}

static const char*
line_parser_gets( LineParser*  p )
{
    for (;;) {
        for (;;) {
            int  c = line_parser_getc(p);

            if (c < 0) {
                close(p->fd);
                p->fd = -1;
                return NULL;
             }
             if (line_parser_addc(p, c))
                return p->buff;
        }
    }
}

static void
line_parser_done( LineParser* p )
{
    if (p->fd >= 0) {
        close(p->fd);
        p->fd = -1;
    }
}

static int
__get_nproc_conf(void)
{
    LineParser   parser[1];
    const char*  p;
    int          count = 0;

    if (line_parser_init(parser, "/proc/cpuinfo") < 0)
        return 1;

    while ((p = line_parser_gets(parser))) {
        if ( !memcmp(p, "processor", 9) )
            count += 1;
    }
    return (count < 1) ? 1 : count;
}


static int
__get_nproc_onln(void)
{
    LineParser   parser[1];
    const char*  p;
    int          count = 0;

    if (line_parser_init(parser, "/proc/stat") < 0)
        return 1;

    while ((p = line_parser_gets(parser))) {
        if ( !memcmp(p, "cpu", 3) && isdigit(p[3]) )
            count += 1;
    }
    return (count < 1) ? 1 : count;
}

static int
__get_phys_pages(void)
{
    LineParser   parser[1];
    const char*  p;

    if (line_parser_init(parser, "/proc/meminfo") < 0)
        return -2;  /* what ? */

    while ((p = line_parser_gets(parser))) {
        long  total;
        if ( sscanf(p, "MemTotal: %ld kB", &total) == 1 ) {
            line_parser_done(parser);
            return (int) (total / (PAGE_SIZE/1024));
        }
    }
    return -3;
}

static int
__get_avphys_pages(void)
{
    LineParser   parser[1];
    const char*  p;

    if (line_parser_init(parser, "/proc/meminfo") < 0)
        return -1;  /* what ? */

    while ((p = line_parser_gets(parser))) {
        long  total;
        if ( sscanf(p, "MemFree: %ld kB", &total) == 1 ) {
            line_parser_done(parser);
            return (int) (total / (PAGE_SIZE/1024));
        }
    }
    return -1;
}