/*
 * wrappers around low-level operations to provide a simpler interface
 * to the operations that Lisp (and some contributed modules) needs.
 *
 * The functions in this file are typically called directly from Lisp.
 * Thus, when their signature changes, they don't need updates in a .h
 * file somewhere, but they do need updates in the Lisp code. FIXME:
 * It would be nice to enforce this at compile time. It mighn't even
 * be all that hard: make the cross-compiler versions of DEFINE-ALIEN-FOO
 * macros accumulate strings in a list which then gets written out at
 * the end of sbcl2.h at the end of cross-compilation, then rerun
 * 'make' in src/runtime/ using the new sbcl2.h as sbcl.h (and make
 * sure that all the files in src/runtime/ include sbcl.h). */

/*
 * This software is part of the SBCL system. See the README file for
 * more information.
 *
 * This software is derived from the CMU CL system, which was
 * written at Carnegie Mellon University and released into the
 * public domain. The software is in the public domain and is
 * provided with absolutely no warranty. See the COPYING and CREDITS
 * files for more information.
 */

#include "sbcl.h"

#include <sys/types.h>
#include <dirent.h>
#include <sys/stat.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <unistd.h>
#include <errno.h>
#include <limits.h>
#include <fcntl.h>
#include <math.h>

#ifndef LISP_FEATURE_WIN32
#include <pwd.h>
#include <time.h>
#include <sys/time.h>
#include <sys/wait.h>
#include <sys/resource.h>
#include <netdb.h>
#endif
#include <stdio.h>

#if defined(LISP_FEATURE_WIN32)
#define WIN32_LEAN_AND_MEAN
#include <errno.h>
#include <math.h>
#endif

#include "runtime.h"
#include "wrap.h"

/* Although it might seem as though this should be in some standard
   Unix header, according to Perry E. Metzger, in a message on
   sbcl-devel dated 2004-03-29, this is the POSIXly-correct way of
   using environ: by an explicit declaration.  -- CSR, 2004-03-30 */
extern char **environ;

/*
 * stuff needed by CL:DIRECTORY and other Lisp directory operations
 */


/*
 * readlink(2) stuff
 */

#ifndef LISP_FEATURE_WIN32
/* a wrapped version of readlink(2):
 *   -- If path isn't a symlink, or is a broken symlink, return 0.
 *   -- If path is a symlink, return a newly allocated string holding
 *      the thing it's linked to. */
char *
wrapped_readlink(char *path)
{
    int bufsiz = strlen(path) + 16;
    while (1) {
        char *result = malloc(bufsiz);
        int n_read = readlink(path, result, bufsiz);
        if (n_read < 0) {
            free(result);
            return 0;
        } else if (n_read < bufsiz) {
            result[n_read] = 0;
            return result;
        } else {
            free(result);
            bufsiz *= 2;
        }
    }
}
#endif

/*
 * realpath(3), including a wrapper for Windows.
 */
char * sb_realpath (char *path)
{
#ifndef LISP_FEATURE_WIN32
    char *ret;
    int errnum;

    if ((ret = calloc(PATH_MAX, sizeof(char))) == NULL)
        return NULL;
    if (realpath(path, ret) == NULL) {
        errnum = errno;
        free(ret);
        errno = errnum;
        return NULL;
    }
    return(ret);
#else
    char *ret;
    char *cp;
    int errnum;

    if ((ret = calloc(MAX_PATH, sizeof(char))) == NULL)
        return NULL;
    if (GetFullPathName(path, MAX_PATH, ret, &cp) == 0) {
        errnum = errno;
        free(ret);
        errno = errnum;
        return NULL;
    }
    return(ret);
#endif
}

/* readdir, closedir, and dirent name accessor. The first three are not strictly
 * necessary, but should save us some #+netbsd in the build, and this also allows
 * building Windows versions using the non-ANSI variants of FindFirstFile &co
 * under the same API. (Use a structure that appends the handle to the WIN32_FIND_DATA
 * as the return value from sb_opendir, on sb_readdir grab the name from the previous
 * call and save the new one.) Nikodemus thought he would have to do that to support
 * DIRECTORY on UNC paths, but turns out opendir &co do TRT on Windows already -- so
 * leaving that bit of tedium for a later date, once we figure out the whole *A vs. *W
 * issue out properly. ...FIXME, obviously, as per above.
 *
 * Once that is done, the lisp side functions are best named OS-OPENDIR, etc.
 */
extern DIR *
sb_opendir(char * name)
{
    return opendir(name);
}

extern struct dirent *
sb_readdir(DIR * dirp)
{
    /* NULL returned from readdir() means it reached the end, NULL and
       non-zero errno means an error occured.
       When no error has occured, errno is not changed.
       Set it to 0 beforehand. */
    errno = 0;
    return readdir(dirp);
}

extern int
sb_closedir(DIR * dirp)
{
    return closedir(dirp);
}

extern char *
sb_dirent_name(struct dirent * ent)
{
    return ent->d_name;
}

/*
 * stat(2) stuff
 */

static void
copy_to_stat_wrapper(struct stat_wrapper *to, struct stat *from)
{
#define FROB(stem) to->wrapped_st_##stem = from->st_##stem
#ifndef LISP_FEATURE_WIN32
#define FROB2(stem) to->wrapped_st_##stem = from->st_##stem
#else
#define FROB2(stem) to->wrapped_st_##stem = 0;
#endif
    FROB(dev);
    FROB2(ino);
    FROB(mode);
    FROB(nlink);
    FROB2(uid);
    FROB2(gid);
    FROB(rdev);
    FROB(size);
    FROB2(blksize);
    FROB2(blocks);
    FROB(atime);
    FROB(mtime);
    FROB(ctime);
#undef FROB
}

int
stat_wrapper(const char *file_name, struct stat_wrapper *buf)
{
    struct stat real_buf;
    int ret;

#ifdef LISP_FEATURE_WIN32
    /*
     * Windows won't match the last component of a pathname if there
     * is a trailing #\/ or #\\, except if it's <drive>:\ or <drive>:/
     * in which case it behaves the other way around. So we remove the
     * trailing directory separator unless we are being passed just a
     * drive name (e.g. "c:\\").  Some, but not all, of this
     * strangeness is documented at Microsoft's support site (as of
     * 2006-01-08, at
     * <http://support.microsoft.com/default.aspx?scid=kb;en-us;168439>)
     */
    char file_buf[MAX_PATH];
    strcpy(file_buf, file_name);
    int len = strlen(file_name);
    if (len != 0 && (file_name[len-1] == '/' || file_name[len-1] == '\\') &&
        !(len == 3 && file_name[1] == ':' && isalpha(file_name[0])))
        file_buf[len-1] = '\0';
    file_name = file_buf;
#endif

    if ((ret = stat(file_name,&real_buf)) >= 0)
        copy_to_stat_wrapper(buf, &real_buf);
    return ret;
}

#ifndef LISP_FEATURE_WIN32
int
lstat_wrapper(const char *file_name, struct stat_wrapper *buf)
{
    struct stat real_buf;
    int ret;
    if ((ret = lstat(file_name,&real_buf)) >= 0)
        copy_to_stat_wrapper(buf, &real_buf);
    return ret;
}
#else
/* cleaner to do it here than in Lisp */
int lstat_wrapper(const char *file_name, struct stat_wrapper *buf)
{
    return stat_wrapper(file_name, buf);
}
#endif

int
fstat_wrapper(int filedes, struct stat_wrapper *buf)
{
    struct stat real_buf;
    int ret;
    if ((ret = fstat(filedes,&real_buf)) >= 0)
        copy_to_stat_wrapper(buf, &real_buf);
    return ret;
}

/* A wrapper for mkstemp(3), for two reasons: (1) mkstemp does not
   exist on Windows; (2) by passing down a mode_t, we don't need a
   binding to chmod in SB-UNIX, and need not concern ourselves with
   umask issues if we want to use mkstemp to make new files in
   OPEN as implied by the cagey remark (in 'unix.lisp') that
     "There are good reasons to implement some OPEN options with a[n]
      mkstemp(3)-like routine, but we don't do that yet." */

int sb_mkstemp (char *template, mode_t mode) {
  int fd;
#ifdef LISP_FEATURE_WIN32
#define PATHNAME_BUFFER_SIZE MAX_PATH
  char buf[PATHNAME_BUFFER_SIZE];

  while (1) {
    /* Fruit fallen from the tree: for people who like
       microoptimizations, we might not need to copy the whole
       template on every loop, but only the last several characters.
       But I didn't feel like testing the boundary cases in Windows's
       _mktemp. */
    strncpy(buf, template, PATHNAME_BUFFER_SIZE);
    buf[PATHNAME_BUFFER_SIZE-1]=0; /* force NULL-termination */
    if (_mktemp(buf)) {
      if ((fd=open(buf, O_CREAT|O_EXCL|O_RDWR, mode))!=-1) {
        strcpy(template, buf);
        return (fd);
      } else
        if (errno != EEXIST)
          return (-1);
    } else
      return (-1);
  }
#undef PATHNAME_BUFFER_SIZE
#else
  /* It makes no sense to reimplement mkstemp() with logic susceptible
     to the exploit that mkstemp() was designed to avoid.
     Unfortunately, there is a subtle bug in this more nearly correct technique.
     open() uses the given creation mode ANDed with the process umask,
     but fchmod() uses exactly the specified mode.  Attempting to perform the
     masking operation manually would result in another race: you can't obtain
     the current mask except by calling umask(), which both sets and gets it.
     But since RUN-PROGRAM is the only use of this, and the mode given is #o600
     which is the default for mkstemp(), RUN-PROGRAM should be indifferent.
     [The GNU C library documents but doesn't implement getumask() by the way.]
     So we're patching a security hole with a known innocuous design flaw
     by necessity to avoid the gcc linker warning that
       "the use of `mktemp' is dangerous, better use `mkstemp'" */
  fd = mkstemp(template);
  if (fd != -1 && fchmod(fd, mode) == -1) {
    close(fd); // got a file descriptor but couldn't fchmod() it
    return -1;
  }
  return fd;
#endif
}


/*
 * getpwuid() stuff
 */

#ifndef LISP_FEATURE_WIN32
/* Return a newly-allocated string holding the username for "uid", or
 * NULL if there's no such user.
 *
 * KLUDGE: We also return NULL if malloc() runs out of memory
 * (returning strdup() result) since it's not clear how to handle that
 * error better. -- WHN 2001-12-28 */
char *
uid_username(int uid)
{
    struct passwd *p = getpwuid(uid);
    if (p) {
        /* The object *p is a static struct which'll be overwritten by
         * the next call to getpwuid(), so it'd be unsafe to return
         * p->pw_name without copying. */
        return strdup(p->pw_name);
    } else {
        return 0;
    }
}

char *
passwd_homedir(struct passwd *p)
{
    if (p) {
        /* Let's be careful about this, shall we? */
        size_t len = strlen(p->pw_dir);
        if (p->pw_dir[len-1] == '/') {
            return strdup(p->pw_dir);
        } else {
            char *result = malloc(len + 2);
            if (result) {
                unsigned int nchars = sprintf(result,"%s/",p->pw_dir);
                if (nchars == len + 1) {
                    return result;
                } else {
                    return 0;
                }
            } else {
                return 0;
            }
        }
    } else {
        return 0;
    }
}

char *
user_homedir(char *name)
{
    return passwd_homedir(getpwnam(name));
}

char *
uid_homedir(uid_t uid)
{
    return passwd_homedir(getpwuid(uid));
}
#endif /* !LISP_FEATURE_WIN32 */

/*
 * functions to get miscellaneous C-level variables
 *
 * (Doing this by calling functions lets us borrow the smarts of the C
 * linker, so that things don't blow up when libc versions and thus
 * variable locations change between compile time and run time.)
 */

char **
wrapped_environ()
{
    return environ;
}

#ifdef LISP_FEATURE_WIN32
#include <windows.h>
#include <time.h>
/*
 * faked-up implementation of select(). Right now just enough to get through
 * second genesis.
 */
int sb_select(int top_fd, DWORD *read_set, DWORD *write_set, DWORD *except_set, time_t *timeout)
{
    /*
     * FIXME: Going forward, we may want to use MsgWaitForMultipleObjects
     * in order to support a windows message loop inside serve-event.
     */
    HANDLE handles[MAXIMUM_WAIT_OBJECTS];
    int fds[MAXIMUM_WAIT_OBJECTS];
    int num_handles;
    int i;
    DWORD retval;
    int polling_write;
    DWORD win_timeout;

    num_handles = 0;
    polling_write = 0;
    for (i = 0; i < top_fd; i++) {
        if (except_set) except_set[i >> 5] = 0;
        if (write_set && (write_set[i >> 5] & (1 << (i & 31)))) polling_write = 1;
        if (read_set[i >> 5] & (1 << (i & 31))) {
            read_set[i >> 5] &= ~(1 << (i & 31));
            fds[num_handles] = i;
            handles[num_handles++] = (HANDLE) _get_osfhandle(i);
        }
    }

    win_timeout = INFINITE;
    if (timeout) win_timeout = (timeout[0] * 1000) + timeout[1];

    /* Last parameter here is timeout in milliseconds. */
    /* retval = WaitForMultipleObjects(num_handles, handles, 0, INFINITE); */
    retval = WaitForMultipleObjects(num_handles, handles, 0, win_timeout);

    if (retval < WAIT_ABANDONED) {
        /* retval, at this point, is the index of the single live HANDLE/fd. */
        read_set[fds[retval] >> 5] |= (1 << (fds[retval] & 31));
        return 1;
    }
    return polling_write;
}
#endif


/* We will need to define these things or their equivalents for Win32
   eventually, but for now let's get it working for everyone else. */
#ifndef LISP_FEATURE_WIN32
/* From SB-BSD-SOCKETS, to get h_errno */
int get_h_errno()
{
    return h_errno;
}

/* From SB-POSIX, wait-macros */
int wifcontinued(int status) {
#ifdef WIFCONTINUED
    return WIFCONTINUED(status);
#else
    return 0;
#endif
}
int wifexited(int status) {
    return WIFEXITED(status);
}
int wexitstatus(int status) {
    return WEXITSTATUS(status);
}
int wifsignaled(int status) {
    return WIFSIGNALED(status);
}
int wtermsig(int status) {
    return WTERMSIG(status);
}
int wifstopped(int status) {
    return WIFSTOPPED(status);
}
int wstopsig(int status) {
    return WSTOPSIG(status);
}
#endif  /* !LISP_FEATURE_WIN32 */

/* From SB-POSIX, stat-macros */
int s_isreg(mode_t mode)
{
    return S_ISREG(mode);
}
int s_isdir(mode_t mode)
{
    return S_ISDIR(mode);
}
int s_ischr(mode_t mode)
{
    return S_ISCHR(mode);
}
int s_isblk(mode_t mode)
{
    return S_ISBLK(mode);
}
int s_isfifo(mode_t mode)
{
    return S_ISFIFO(mode);
}
#ifndef LISP_FEATURE_WIN32
int s_islnk(mode_t mode)
{
#ifdef S_ISLNK
    return S_ISLNK(mode);
#else
    return ((mode & S_IFMT) == S_IFLNK);
#endif
}
int s_issock(mode_t mode)
{
#ifdef S_ISSOCK
    return S_ISSOCK(mode);
#else
    return ((mode & S_IFMT) == S_IFSOCK);
#endif
}
#endif /* !LISP_FEATURE_WIN32 */

#ifdef LISP_FEATURE_UNIX
#ifdef LISP_FEATURE_DARWIN
/* nanosleep() is not re-entrant on some versions of Darwin and is
 * reimplemented using the underlying syscalls.
 */
int sb_nanosleep(time_t sec, int nsec);
#else
void sb_nanosleep(time_t sec, int nsec)
{
    struct timespec rqtp = {sec, nsec};
    struct timespec rmtp;

    while(nanosleep(&rqtp, &rmtp) && errno == EINTR) {
        rqtp = rmtp;
        /* The old lisp version stated
           ;; KLUDGE: On Darwin, if an interrupt cases nanosleep to
           ;; take longer than the requested time, the call will
           ;; return with EINT and (unsigned)-1 seconds in the
           ;; remainder timespec, which would cause us to enter
           ;; nanosleep again for ~136 years. So, we check that the
           ;; remainder time is actually decreasing.
           ;;
           ;; It would be neat to do this bit of defensive
           ;; programming on all platforms, but unfortunately on
           ;; Linux, REM can be a little higher than REQ if the
           ;; nanosleep() call is interrupted quickly enough,
           ;; probably due to the request being rounded up to the
           ;; nearest HZ. This would cause the sleep to return way
           ;; too early.
           #+darwin
           (let ((rem-sec (slot rem 'tv-sec))
           (rem-nsec (slot rem 'tv-nsec)))
           (when (or (> secs rem-sec)
           (and (= secs rem-sec) (>= nsecs rem-nsec)))
           ;; Update for next round.
           (setf secs  rem-sec
           nsecs rem-nsec)
           t)

           but the Darwin variant is implemented elsewhere
        */
    }
}
#endif

void sb_nanosleep_double(double seconds) {
    /* Some (which?) platforms, apparently, can't sleep more than 100
       million seconds */
    for (; seconds > 0; seconds -= 100000000.0) {
        long sec = truncl(seconds);
        long nsec = truncl((seconds - (double) sec) * 1e9);
        sb_nanosleep(sec, nsec);

    }
}
void sb_nanosleep_float(float seconds) {
    sb_nanosleep_double(seconds);
}
#endif

#ifdef LISP_FEATURE_NETBSD
/* These thin wrappers are needed due to "linker rewriting"
 * acording to git revision 9304704f68 */
int sb_getrusage(int who, struct rusage *rusage)
{
        return getrusage(who, rusage);
}

int sb_gettimeofday(struct timeval *tp, void *tz)
{
        return gettimeofday(tp, tz);
}

int sb_select(int nfds, fd_set *readfds, fd_set *writefds, fd_set *exceptfds,
    struct timeval *timeout)
{
        return select(nfds, readfds, writefds, exceptfds, timeout);
}

int sb_getitimer(int which, struct itimerval *value)
{
        return getitimer(which, value);
}

int sb_setitimer(int which, struct itimerval *value, struct itimerval *ovalue)
{
        return setitimer(which, value, ovalue);
}

int sb_utimes(char *path, struct timeval times[2])
{
    return utimes(path, times);
}

int sb_clock_gettime(clockid_t id, struct timespec* tp)
{
    return clock_gettime(id, tp);
}
#ifndef LISP_FEATURE_SB_THREAD
#include <signal.h>
int sb_sigprocmask(int how, const sigset_t *set, sigset_t *oldset)
{
    return sigprocmask(how, set, oldset);
}
#endif
#endif

#ifdef LISP_FEATURE_WIN32

// These are used in src/code/irrat.lisp. Search for DEF-MATH-RTN
#define SB_TRIG_WRAPPER(name) \
    double sb_##name (double x) {               \
        return name(x);                         \
    }
SB_TRIG_WRAPPER(acos)
SB_TRIG_WRAPPER(asin)
SB_TRIG_WRAPPER(cosh)
SB_TRIG_WRAPPER(sinh)
SB_TRIG_WRAPPER(tanh)
SB_TRIG_WRAPPER(asinh)
SB_TRIG_WRAPPER(acosh)
SB_TRIG_WRAPPER(atanh)

double sb_hypot (double x, double y) {
    return hypot(x, y);
}

#endif
