/* Scheme48/scsh Unix system interface.
** Routines that require custom C support.
** Copyright (c) 1993,1994 by Olin Shivers.
*/

#include "sysdep.h"
#include <stdio.h>
#include <stdlib.h>
#include <sys/signal.h>
#include <sys/types.h>
#include <sys/times.h>
#include <sys/time.h>
#include <fcntl.h>		/* for O_RDWR */
#include <sys/stat.h>
#include <sys/param.h> /* For gethostname() */

#include <netdb.h>
/* This lossage brought to you by Solaris and BIND */
/* We thank Solaris for forcing users to get a new BIND */
/* We thank BIND for blowing away the Solaris includea for MAXHOSTNAMELEN */
#ifndef MAXHOSTNAMELEN		
#include <arpa/nameser.h>
#ifndef MAXHOSTNAMELEN		
#define MAXHOSTNAMELEN      MAXDNAME
#endif
#endif

#include <pwd.h>
#include <errno.h>
#include <sys/wait.h>
#include <unistd.h>
#include <string.h>
#include <utime.h>

#include "cstuff.h"
#include "machine/stdio_dep.h"

/* Make sure our exports match up w/the implementation: */
#include "syscalls1.h"

extern int errno;
extern char **environ;

/* Sux because it's dependent on 32-bitness. */
#define hi8(i)  (((i)>>24) & 0xff)
#define lo24(i) ((i) & 0xffffff)
#define comp8_24(hi, lo) (((hi)<<24) + (lo))


/* Process stuff
*******************************************************************************
** wait, exec
*/

/* Args: pid, flags; returns [retval, status] */

s48_value wait_pid(int pid, int flags, int *result_pid, int *status)
{
    *result_pid = waitpid(pid, status, flags);
    return (*result_pid == -1) ? s48_enter_fixnum(errno) : S48_FALSE;
    }


/* env:  Scheme vector of Scheme strings, e.g., #("TERM=vt100" ...) or #T.
** argv: Scheme vector of Scheme strings.
** prog: String.
** 
** We don't typecheck the args. You must do the typechecking
** on the Scheme side.
*/

int scheme_exec(const char *prog, s48_value argv, s48_value env)
{
  int i, j, e;
  int argc = S48_VECTOR_LENGTH(argv);

  char **unix_argv = Malloc(char*, argc+1);
  char **unix_env;

  if( unix_argv == NULL ) return errno;

  /* Scheme->Unix convert the argv parameter. */
  for(i=0; i<argc; i++)
    unix_argv[i] = cig_string_body(S48_VECTOR_REF(argv,i));
  unix_argv[argc] = NULL;

  /* Scheme->Unix convert the env parameter. */
  if( env == S48_TRUE ) unix_env = environ;
  else {
    int envlen = S48_VECTOR_LENGTH(env);
    unix_env = Malloc(char*, envlen+1);

    if( !unix_env ) goto lose;

    for(j=0; j<envlen; j++)
      unix_env[j] = cig_string_body(S48_VECTOR_REF(env,j));
    unix_env[envlen] = NULL;
  }

  execve(prog, unix_argv, unix_env); /* Do it. */

  if( env != S48_TRUE ) {
    e = errno;
    Free(unix_env);
    errno = e;
  }
 lose:
  e = errno;
  Free(unix_argv);
  return e;
}


/* Random file and I/O stuff
*******************************************************************************
*/

/* Returns [errno, r, w] */
int scheme_pipe(int *r, int *w)
{
  int fds[2];
  if( pipe(fds) ) {
    *r = 0; *w = 0;
    return errno;
  }

  *r = fds[0]; *w = fds[1];
  return 0;
}


/* Read the symlink into static memory. Return NULL on error. */

static char linkpath[MAXPATHLEN+1]; /*  Maybe unaligned. Not reentrant. */

char const *scm_readlink(const char *path)
{
  int retval = readlink(path, linkpath, MAXPATHLEN);

  return (char const *)
      ((retval == -1) ? NULL : ( linkpath[retval] = '\0', linkpath ));
}



/* Scheme interfaces to utime(). 
** Complicated by need to pass real 32-bit quantities.
*/

int scm_utime(char const *path, time_t ac, time_t mod)
{
    struct utimbuf t;
    t.actime = ac;
    t.modtime = mod;
    return utime(path, &t);
}

int scm_utime_now(char const *path) {return utime(path, 0);}


int set_cloexec(int fd, int val)
{
  int flags = fcntl(fd, F_GETFD);
  if( flags == -1 ) return errno;
  val = -val;	/* 0 -> 0 and 1 -> -1 */

  /* If it's already what we want, just return. */
  if( (flags & FD_CLOEXEC) == (FD_CLOEXEC & val) ) return 0;

  flags = (flags & ~FD_CLOEXEC) | (val & FD_CLOEXEC);
  return fcntl(fd, F_SETFD, flags) ? errno : 0;
  }


/* Two versions of CWD
*******************************************************************************
*/

/* Posix rules: If PATH_MAX is defined, it's the length of longest path.
** Otherwise, _POSIX_PATH_MAX = 255, and is a lower bound on said length.
** I'm writing out 255 as a literal because HP-UX isn't finding 
** _POSIX_PATH_MAX.
*/
#ifdef PATH_MAX
#define scsh_path_max (PATH_MAX)
#else
#define scsh_path_max (255)
#endif

/* Simple-minded POSIX version. */
int scheme_cwd(const char **dirp)
{
  char *buf;
  int size = scsh_path_max + 1; /* +1 for terminating nul byte... */

  buf = Malloc(char,size);
  if(!buf) goto lose;

  while( !getcwd(buf, size) )
    if( errno != ERANGE ) goto lose;
    else {
      /* Double the buf and retry. */
      char *nbuf = Realloc(char, buf, size += size);
      if( !nbuf ) goto lose;
      buf = nbuf;
    }

  *dirp = (const char*) buf;		/* win */
  return 0;

 lose:
  {int e = errno;
   Free(buf);
   *dirp = 0;
   return e;}
}


#if 0
/* Faster SUNOS version. */
/* We have to use malloc, because the stub is going to free the string. */

int scheme_cwd(const char **dirp)
{
  char *buf = Malloc(char,MAXPATHLEN); 
  int e;

  if( buf && getwd(buf) ) {
    *dirp = (const char*) buf;
    return 0;
  }

  /* lose */
  e = errno;
  Free(buf);
  *dirp = 0;
  return e;
}
#endif


/* Process times
*******************************************************************************
*/

/* Sleazing on the types here -- the ret values should be clock_t, not int,
** but cig can't handle it.
*/

int process_times(clock_t *utime, clock_t *stime, 
		  clock_t *cutime, clock_t *cstime)
{
    struct tms tms;
    clock_t t = times(&tms);
    if (t == -1) return -1;
    *utime = tms.tms_utime;
    *stime = tms.tms_stime;
    *cutime = tms.tms_cutime;
    *cstime = tms.tms_cstime;
    return t;
    }

int cpu_clock_ticks_per_sec() 
{
#ifdef _SC_CLK_TCK
  static long clock_tick = 0;
    
  if (clock_tick == 0)
    clock_tick = sysconf(_SC_CLK_TCK); /* POSIX.1, POSIX.2 */
  return clock_tick;
#else
#ifdef CLK_TCK
  return CLK_TCK;
#else
  return 60;
#endif
#endif    
}

/* Reading and writing
*******************************************************************************
*/

/* Return a char, #f (EOF), or errno. */
s48_value read_fdes_char(int fd)
{
  int i; char c;
  if( (i=read(fd, &c, 1)) < 0 ) return s48_enter_fixnum(errno);
  if(i==0) return S48_FALSE;
  return s48_enter_char(c);
}

int write_fdes_char(char c, int fd)  {return write(fd, &c, 1);}


ssize_t read_fdes_substring(s48_value buf, size_t start, size_t end, int fd)
{
  return read(fd, StrByte(buf,start), end-start);
}

ssize_t write_fdes_substring(s48_value buf, size_t start, size_t end, int fd)
{
  return write(fd, StrByte(buf,start), end-start);
}


/*
** Stat hackery
*******************************************************************************
** DANGER, WILL ROBINSON: It's not necessarily true that all these 
** stat fields will fit into a fixnum.
** In fact, S48's 30 bit fixnums are almost certainly good enough
** for everything but times. 30 signed bits ran out in 1987.
** So the time fields are split, low 24, high everything else.
** I haven't bothered w/anything else, since the only other real limit
** is size -- files can't be bigger than .5Gb. 
*/

/* S_ISSOCK(mode) and S_ISLNK(mode) are not POSIX. You lose on a NeXT. Ugh. */
#ifndef S_ISSOCK
#define S_ISSOCK(mode) (((mode) & S_IFMT) == S_IFSOCK)
#endif
#ifndef S_ISLNK
#define S_ISLNK(mode) (((mode) & S_IFMT) == S_IFLNK)
#endif

#define low24(x) ((x) & 0xffffff)
#define hi_but24(x) (((x) >> 24) & 0xff)

/* Note that hi_but24 assumes value is a *32 bit* signed value. We have to
** do this, because C's right-shift operator exposes word width. A suckful
** language.
*/

/* Internal aux function -- loads stat values into Scheme vector: */
static int really_stat(int retval, struct stat *s, s48_value vec)
{
  int modes, typecode = -1;

  if( 11 != S48_VECTOR_LENGTH(vec) ) return -1;
  if( retval < 0 ) return errno;

  modes = s->st_mode;
  if( S_ISBLK(modes) )       typecode = 0;
  else if( S_ISCHR(modes) )  typecode = 1;
  else if( S_ISDIR(modes) )  typecode = 2;
  else if( S_ISFIFO(modes) ) typecode = 3;
  else if( S_ISREG(modes) )  typecode = 4;
  else if( S_ISSOCK(modes) ) typecode = 5;
  else if( S_ISLNK(modes) )  typecode = 6;
    
  S48_VECTOR_SET(vec,0,s48_enter_fixnum(typecode));
  S48_VECTOR_SET(vec,1, s48_enter_fixnum(s->st_dev));
  S48_VECTOR_SET(vec,2, s48_enter_fixnum(s->st_ino));
  S48_VECTOR_SET(vec,3, s48_enter_fixnum(s->st_mode));
  S48_VECTOR_SET(vec,4, s48_enter_fixnum(s->st_nlink));
  S48_VECTOR_SET(vec,5, s48_enter_fixnum(s->st_uid));
  S48_VECTOR_SET(vec,6, s48_enter_fixnum(s->st_gid));
  S48_VECTOR_SET(vec,7, s48_enter_fixnum(s->st_size));

  S48_VECTOR_SET(vec,8, s48_enter_integer(s->st_atime));
  S48_VECTOR_SET(vec,9, s48_enter_integer(s->st_mtime));
  S48_VECTOR_SET(vec,10, s48_enter_integer(s->st_ctime));

  /* We also used to do st_rdev, st_blksize, and st_blocks.
     These aren't POSIX, and, e.g., are not around on SGI machines.
     Too bad -- blksize is useful. Unix sux. */

  return 0;
}

int scheme_stat(const char *path, s48_value vec, int chase_p)
{
  struct stat s;
  return really_stat(chase_p ? stat(path, &s) : lstat(path, &s), &s, vec);
}

int scheme_fstat(int fd, s48_value vec)
{
  struct stat s;
  return really_stat(fstat(fd,&s), &s, vec);
}


/* Supplementary groups access
*******************************************************************************
*/

int num_supp_groups(void)
{
  return getgroups(0,NULL);
}

/* Load the supplementary groups into GVEC. */

int get_groups(s48_value gvec)
{
  int veclen = S48_VECTOR_LENGTH(gvec), i, retval;
  gid_t gvec0[20], *gp = gvec0;

  if( veclen > 20 )
    if( NULL == (gp=Malloc(gid_t,veclen)) ) return -1;

  retval = getgroups(veclen, gp);
    
  if( retval != -1 )
    for( i=veclen; i--; )
      S48_VECTOR_SET(gvec,i, s48_enter_fixnum(gp[i]));

  if( veclen > 20 ) Free(gp);

  return retval;
}
    

/* Environment hackery
*******************************************************************************
*/

int put_env(const char *s)
{
  char *s1 = Malloc(char, strlen(s)+1);
  if( !s1 ) return s48_enter_fixnum(errno);
    
  strcpy(s1, s);

  return putenv(s1) ? s48_enter_fixnum(errno) : S48_FALSE;
}

char** scm_envvec(int *len)	/* Returns environ c-vector & its length. */
{
  char **ptr=environ;
  while( *ptr ) ptr++;
  *len = ptr-environ;

  return(environ);
}

/* Load the (Scheme) strings in the (Scheme) vector VEC into environ.
** Somewhat wasteful of memory: we do not free any of the memory
** in the old environ -- don't know if it is being shared elsewhere.
*/

int install_env(s48_value vec)
{
  int i, envsize;
  char **newenv;

  envsize = S48_VECTOR_LENGTH(vec);
  newenv = Malloc(char*, envsize+1);
  if( !newenv ) return errno;

  for( i=0; i<envsize; i++ ) {
    char *s = scheme2c_strcpy(S48_VECTOR_REF(vec,i));
    if (!s) {
      /* Return all the memory and bail out. */
      int e = errno;
      while(--i) Free(newenv[i]);
      Free(newenv);
      return e;
    }
    newenv[i] = s;
  }

  newenv[i] = NULL;
  environ = newenv;
  return 0;
}


/* Delete the env var. */
void delete_env(const char *var)
{
  int varlen = strlen(var);
  char **ptr = environ-1;

  do if( !*++ptr ) return;
  while( strncmp(*ptr, var, varlen) || (*ptr)[varlen] != '=' );

  do ptr[0] = ptr[1]; while( *++ptr ); 
}	


/*****************************************************************************/

/* N.B.: May be unaligned. 
** Not re-entrant, either -- will puke if multithreaded.
*/
static char hostname[MAXHOSTNAMELEN+1]; 

char *scm_gethostname(void)
{
    /* different OS's declare differently, so punt the prototype. */
    int gethostname(); 
    gethostname(hostname, MAXHOSTNAMELEN);
    return hostname;
}

#include <errno.h>

char *errno_msg(int i)
{
#ifdef HAVE_STRERROR
    return(strerror(i));
#else
    /* temp hack until we figure out what to do about losing sys_errlist's */
    extern
#ifdef HAVE_CONST_SYS_ERRLIST
	const
#endif
	    char *sys_errlist[]; 
    extern int sys_nerr;
    return ( i < 0 || i > sys_nerr ) ? NULL /* i.e., #f */
	: (char*) sys_errlist[i];
#endif /* !HAVE_STRERROR */
}

/* Some of fcntl()
******************
*/

int fcntl_read(int fd, int command)
{ return fcntl(fd, command); }


int fcntl_write(int fd, int command, int value)
{ return fcntl(fd, command, value); }