syscalls.c

/* Support files for GNU libc.  Files in the system namespace go here.
   Files in the C namespace (ie those that do not start with an
   underscore) go in .c.  */

#include <_ansi.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/fcntl.h>
#include <stdio.h>
#include <time.h>
#include <sys/time.h>
#include <sys/times.h>
#include <errno.h>
#include <reent.h>
#include <signal.h>
#include <unistd.h>
#include <sys/wait.h>
#include "swi.h"

/* Forward prototypes.  */
int	_system		(const char *);
int	_rename		(const char *, const char *);
int	_isatty		(int);
clock_t _times		(struct tms *);
int	_gettimeofday	(struct timeval *, void *);
void	_raise		(void);
int	_unlink		(const char *);
int	_link		(const char *, const char *);
int	_stat		(const char *, struct stat *);
int	_fstat		(int, struct stat *);
void *	_sbrk		(ptrdiff_t);
pid_t	_getpid		(void);
int	_kill		(int, int);
void	_exit		(int);
int	_close		(int);
int	_swiclose	(int);
int	_open		(const char *, int, ...);
int	_swiopen	(const char *, int);
int	_write		(int, const void *, size_t);
int	_swiwrite	(int, const void *, size_t);
_off_t	_lseek		(int, _off_t, int);
_off_t	_swilseek	(int, _off_t, int);
int	_read		(int, void *, size_t);
int	_swiread	(int, void *, size_t);
void	initialise_monitor_handles (void);

static int	wrap		(int);
static int	error		(int);
static int	get_errno	(void);
static int	remap_handle	(int);
static int	findslot	(int);
static int	_kill_shared	(int, int, int) __attribute__((__noreturn__));

/* Register name faking - works in collusion with the linker.  */
register char * stack_ptr asm ("sp");


/* following is copied from libc/stdio/local.h to check std streams */
extern void   __sinit (struct _reent *);
#define CHECK_INIT(ptr) \
  do						\
    {						\
      if (!_REENT_IS_NULL(ptr) &&		\
	  !_REENT_CLEANUP(ptr))			\
	__sinit (ptr);				\
    }						\
  while (0)

/* Adjust our internal handles to stay away from std* handles.  */
#define FILE_HANDLE_OFFSET (0x20)

static int monitor_stdin;
static int monitor_stdout;
static int monitor_stderr;

/* Struct used to keep track of the file position, just so we
   can implement fseek(fh,x,SEEK_CUR).  */
typedef struct
{
  int handle;
  off_t pos;
}
poslog;

#define MAX_OPEN_FILES 20
static poslog openfiles [MAX_OPEN_FILES];

static int
findslot (int fh)
{
  int i;
  for (i = 0; i < MAX_OPEN_FILES; i ++)
    if (openfiles[i].handle == fh)
      break;
  return i;
}

/* Function to convert std(in|out|err) handles to internal versions.  */
static int
remap_handle (int fh)
{
  CHECK_INIT(_REENT);

  if (fh == STDIN_FILENO)
    return monitor_stdin;
  if (fh == STDOUT_FILENO)
    return monitor_stdout;
  if (fh == STDERR_FILENO)
    return monitor_stderr;

  return fh - FILE_HANDLE_OFFSET;
}

void
initialise_monitor_handles (void)
{
  int i;
  
  /* Open the standard file descriptors by opening the special
   * teletype device, ":tt", read-only to obtain a descriptor for
   * standard input and write-only to obtain a descriptor for standard
   * output. Finally, open ":tt" in append mode to obtain a descriptor
   * for standard error. Since this is a write mode, most kernels will
   * probably return the same value as for standard output, but the
   * kernel can differentiate the two using the mode flag and return a
   * different descriptor for standard error.
   */

#ifdef ARM_RDI_MONITOR
  int volatile block[3];

  block[0] = (int) ":tt";
  block[2] = 3;     /* length of filename */
  block[1] = 0;     /* mode "r" */
  monitor_stdin = do_AngelSWI (AngelSWI_Reason_Open, (void *) block);

  block[0] = (int) ":tt";
  block[2] = 3;     /* length of filename */
  block[1] = 4;     /* mode "w" */
  monitor_stdout = monitor_stderr
    = do_AngelSWI (AngelSWI_Reason_Open, (void *) block);
#else
  int fh;
  const char * name;

  name = ":tt";
  asm ("mov r0,%2; mov r1, #0; swi %a1; mov %0, r0"
       : "=r"(fh)
       : "i" (SWI_Open),"r"(name)
       : "r0","r1");
  monitor_stdin = fh;

  name = ":tt";
  asm ("mov r0,%2; mov r1, #4; swi %a1; mov %0, r0"
       : "=r"(fh)
       : "i" (SWI_Open),"r"(name)
       : "r0","r1");
  monitor_stdout = monitor_stderr = fh;
#endif

  for (i = 0; i < MAX_OPEN_FILES; i ++)
    openfiles[i].handle = -1;

  openfiles[0].handle = monitor_stdin;
  openfiles[0].pos = 0;
  openfiles[1].handle = monitor_stdout;
  openfiles[1].pos = 0;
}

static int
get_errno (void)
{
#ifdef ARM_RDI_MONITOR
  return do_AngelSWI (AngelSWI_Reason_Errno, NULL);
#else
  register int r0 asm("r0");
  asm ("swi %a1" : "=r"(r0) : "i" (SWI_GetErrno));
  return r0;
#endif
}

/* Set errno and return result. */
static int
error (int result)
{
  errno = get_errno ();
  return result;
}

static int
wrap (int result)
{
  if (result == -1)
    return error (-1);
  return result;
}

/* file, is a valid user file handle.
   ptr, is a null terminated string.
   len, is the length in bytes to read. 
   Returns the number of bytes *not* written. */
int
_swiread (int file, void * ptr, size_t len)
{
  int fh = remap_handle (file);
#ifdef ARM_RDI_MONITOR
  int block[3];

  block[0] = fh;
  block[1] = (int) ptr;
  block[2] = (int) len;

  return do_AngelSWI (AngelSWI_Reason_Read, block);
#else
  register int r0 asm("r0") = fh;
  register int r1 asm("r1") = (int) ptr;
  register int r2 asm("r2") = (int) len;
  asm ("swi %a4"
       : "=r" (r0)
       : "0"(r0), "r"(r1), "r"(r2), "i"(SWI_Read));
  return r0;
#endif
}

/* file, is a valid user file handle.
   Translates the return of _swiread into
   bytes read. */
int __attribute__((weak))
_read (int file, void * ptr, size_t len)
{
  int slot = findslot (remap_handle (file));
  int x = _swiread (file, ptr, len);

  if (x < 0)
    return error (-1);

  if (slot != MAX_OPEN_FILES)
    openfiles [slot].pos += len - x;

  /* x == len is not an error, at least if we want feof() to work.  */
  return len - x;
}

/* file, is a user file descriptor. */
off_t
_swilseek (int file, off_t ptr, int dir)
{
  _off_t res;
  int fh = remap_handle (file);
  int slot = findslot (fh);

  if (dir == SEEK_CUR)
    {
      off_t pos;
      if (slot == MAX_OPEN_FILES)
	return -1;
      pos = openfiles[slot].pos;

      /* Avoid SWI SEEK command when just querying file position. */
      if (ptr == 0)
	return pos;

      ptr += pos;
      dir = SEEK_SET;
    }

#ifdef ARM_RDI_MONITOR
  int block[2];
  if (dir == SEEK_END)
    {
      block[0] = fh;
      ptr += do_AngelSWI (AngelSWI_Reason_FLen, block);
    }

  /* This code only does absolute seeks.  */
  block[0] = remap_handle (file);
  block[1] = ptr;
  res = do_AngelSWI (AngelSWI_Reason_Seek, block);
#else
  register int r0 asm("r0");
  register int r1 asm("r1");
  if (dir == SEEK_END)
    {
      r0 = (int) fh;
      asm ("swi %a2"
	   : "=r" (r0)
	   : "0"(r0), "i" (SWI_Flen));
      res = r0;
      ptr += res;
    }

  /* This code only does absolute seeks.  */
  r0 = (int) fh;
  r1 = (int) ptr;
  asm ("swi %a3"
       : "=r" (r0)
       : "0"(r0), "r"(r1), "i" (SWI_Seek));
  res = r0;
#endif

  if (slot != MAX_OPEN_FILES && res == 0)
    openfiles[slot].pos = ptr;

  /* This is expected to return the position in the file.  */
  return res == 0 ? ptr : -1;
}

off_t
_lseek (int file, off_t ptr, int dir)
{
  return wrap (_swilseek (file, ptr, dir));
}

/* file, is a valid internal file handle.
   Returns the number of bytes *not* written. */
int
_swiwrite (int file, const void * ptr, size_t len)
{
  int fh = remap_handle (file);
#ifdef ARM_RDI_MONITOR
  int block[3];

  block[0] = fh;
  block[1] = (int) ptr;
  block[2] = (int) len;

  return do_AngelSWI (AngelSWI_Reason_Write, block);
#else
  register int r0 asm("r0") = fh;
  register int r1 asm("r1") = (int) ptr;
  register int r2 asm("r2") = (int) len;

  asm ("swi %a4"
       : "=r" (r0)
       : "0"(fh), "r"(r1), "r"(r2), "i"(SWI_Write));
  return r0;
#endif
}

/* file, is a user file descriptor. */
int __attribute__((weak))
_write (int file, const void * ptr, size_t len)
{
  int slot = findslot (remap_handle (file));
  int x = _swiwrite (file, ptr, len);

  if (x == -1 || x == len)
    return error (-1);

  if (slot != MAX_OPEN_FILES)
    openfiles[slot].pos += len - x;

  return len - x;
}

extern int strlen (const char *);

int
_swiopen (const char * path, int flags)
{
  int aflags = 0, fh;
#ifdef ARM_RDI_MONITOR
  int block[3];
#endif

  int i = findslot (-1);

  if (i == MAX_OPEN_FILES)
    return -1;

  /* The flags are Unix-style, so we need to convert them.  */
#ifdef O_BINARY
  if (flags & O_BINARY)
    aflags |= 1;
#endif

  if (flags & O_RDWR)
    aflags |= 2;

  if (flags & O_CREAT)
    aflags |= 4;

  if (flags & O_TRUNC)
    aflags |= 4;

  if (flags & O_APPEND)
    {
      aflags &= ~4; /* Can't ask for w AND a; means just 'a'.  */
      aflags |= 8;
    }

#ifdef ARM_RDI_MONITOR
  block[0] = (int) path;
  block[2] = strlen (path);
  block[1] = aflags;

  fh = do_AngelSWI (AngelSWI_Reason_Open, block);

#else
  register int r0 asm("r0") = (int) path;
  register int r1 asm("r1") = (int) aflags;;
  asm ("swi %a3"
       : "=r"(r0)
       : "0"(r0), "r"(r1), "i" (SWI_Open));
  fh = r0;
#endif

  if (fh >= 0)
    {
      openfiles[i].handle = fh;
      openfiles[i].pos = 0;
    }

  return fh >= 0 ? fh + FILE_HANDLE_OFFSET : error (fh);
}

int
_open (const char * path, int flags, ...)
{
  return wrap (_swiopen (path, flags));
}

int
_swiclose (int file)
{
  int myhan = remap_handle (file);
  int slot = findslot (myhan);

  if (slot != MAX_OPEN_FILES)
    openfiles[slot].handle = -1;

#ifdef ARM_RDI_MONITOR
  return do_AngelSWI (AngelSWI_Reason_Close, & myhan);
#else
  register int r0 asm("r0") = myhan;
  asm ("swi %a2" : "=r"(r0): "0"(r0), "i" (SWI_Close));
  return r0;
#endif
}

int
_close (int file)
{
  return wrap (_swiclose (file));
}

static int
_kill_shared (int pid, int sig, int reason)
{
  (void) pid; (void) sig;
#ifdef ARM_RDI_MONITOR
  /* Note: The pid argument is thrown away.  */
  int block[2];
  block[1] = sig;
  block[0] = reason;
  int insn;

#if SEMIHOST_V2
  if (_has_ext_exit_extended ())
    {
      insn = AngelSWI_Reason_ReportExceptionExtended;
    }
  else
#endif
    {
      insn = AngelSWI_Reason_ReportException;
    }

#if SEMIHOST_V2
if (_has_ext_exit_extended ())
  do_AngelSWI (insn, block);
else
#endif
  do_AngelSWI (insn, (void*)block[0]);

#else
  asm ("swi %a0" :: "i" (SWI_Exit));
#endif

  __builtin_unreachable();
}

int
_kill (int pid, int sig)
{
  if (sig == SIGABRT)
    _kill_shared (pid, sig, ADP_Stopped_RunTimeError);
  else
    _kill_shared (pid, sig, ADP_Stopped_ApplicationExit);
}

void
_exit (int status)
{
  /* The same SWI is used for both _exit and _kill.
     For _exit, call the SWI with "reason" set to ADP_Stopped_ApplicationExit
     to mark a standard exit.
     Note: The RDI implementation of _kill_shared throws away all its
     arguments and all implementations ignore the first argument.  */
  _kill_shared (-1, status, ADP_Stopped_ApplicationExit);
}

pid_t
_getpid (void)
{
  return (pid_t)1;
}

/* Heap limit returned from SYS_HEAPINFO Angel semihost call.  */
uint __heap_limit = 0xcafedead;

void * __attribute__((weak))
_sbrk (ptrdiff_t incr)
{
  extern char   end asm ("end"); /* Defined by the linker.  */
  static char * heap_end;
  char *        prev_heap_end;

  if (heap_end == NULL)
    heap_end = & end;

  prev_heap_end = heap_end;

  if ((heap_end + incr > stack_ptr)
      /* Honour heap limit if it's valid.  */
      || (__heap_limit != 0xcafedead && heap_end + incr > (char *)__heap_limit))
    {
      /* Some of the libstdc++-v3 tests rely upon detecting
	 out of memory errors, so do not abort here.  */
#if 0
      extern void abort (void);

      _write (1, "_sbrk: Heap and stack collision\n", 32);

      abort ();
#else
      errno = ENOMEM;
      return (void *) -1;
#endif
    }

  heap_end += incr;

  return (void *) prev_heap_end;
}

extern void memset (struct stat *, int, unsigned int);

int __attribute__((weak))
_fstat (int file, struct stat * st)
{
  memset (st, 0, sizeof (* st));
  st->st_mode = S_IFCHR;
  st->st_blksize = 1024;
  return 0;
  file = file;
}

int __attribute__((weak))
_stat (const char *fname, struct stat *st)
{
  int file;

  /* The best we can do is try to open the file readonly.  If it exists,
     then we can guess a few things about it.  */
  if ((file = _open (fname, O_RDONLY)) < 0)
    return -1;

  memset (st, 0, sizeof (* st));
  st->st_mode = S_IFREG | S_IREAD;
  st->st_blksize = 1024;
  _swiclose (file); /* Not interested in the error.  */
  return 0;
}

int __attribute__((weak))
_link (const char *__path1 __attribute__ ((unused)), const char *__path2 __attribute__ ((unused)))
{
  errno = ENOSYS;
  return -1;
}

int
_unlink (const char *path)
{
#ifdef ARM_RDI_MONITOR
  int block[2];
  block[0] = (int)path;
  block[1] = strlen(path);
  return wrap (do_AngelSWI (AngelSWI_Reason_Remove, block)) ? -1 : 0;
#else
  errno = ENOSYS;
  return -1;
#endif
}

void
_raise (void)
{
  return;
}

int
_gettimeofday (struct timeval * tp, void * tzvp)
{
  struct timezone *tzp = tzvp;
  if (tp)
    {
    /* Ask the host for the seconds since the Unix epoch.  */
#ifdef ARM_RDI_MONITOR
      tp->tv_sec = do_AngelSWI (AngelSWI_Reason_Time,NULL);
#else
      {
	register int r0 asm("r0");
	asm ("swi %a1" : "=r" (r0): "i" (SWI_Time));
	tp->tv_sec = r0;
      }
#endif
      tp->tv_usec = 0;
    }

  /* Return fixed data for the timezone.  */
  if (tzp)
    {
      tzp->tz_minuteswest = 0;
      tzp->tz_dsttime = 0;
    }

  return 0;
}

/* Return a clock that ticks at 100Hz.  */
clock_t
_times (struct tms * tp)
{
  clock_t timeval;

#ifdef ARM_RDI_MONITOR
  timeval = do_AngelSWI (AngelSWI_Reason_Clock, NULL);
#else
  register int r0 asm("r0");
  asm ("swi %a1" : "=r" (r0): "i" (SWI_Clock));
  timeval = (clock_t) r0;
#endif

  if (tp)
    {
      tp->tms_utime  = timeval;	/* user time */
      tp->tms_stime  = 0;	/* system time */
      tp->tms_cutime = 0;	/* user time, children */
      tp->tms_cstime = 0;	/* system time, children */
    }

  return timeval;
};


int
_isatty (int fd)
{
#ifdef ARM_RDI_MONITOR
  int fh = remap_handle (fd);
  return wrap (do_AngelSWI (AngelSWI_Reason_IsTTY, &fh));
#else
  return (fd <= 2) ? 1 : 0;  /* one of stdin, stdout, stderr */
#endif
}

int
_system (const char *s)
{
#ifdef ARM_RDI_MONITOR
  int block[2];
  int e;

  /* Hmmm.  The ARM debug interface specification doesn't say whether
     SYS_SYSTEM does the right thing with a null argument, or assign any
     meaning to its return value.  Try to do something reasonable....  */
  if (!s)
    return 1;  /* maybe there is a shell available? we can hope. :-P */
  block[0] = (int)s;
  block[1] = strlen (s);
  e = wrap (do_AngelSWI (AngelSWI_Reason_System, block));
  if ((e >= 0) && (e < 256))
    {
      /* We have to convert e, an exit status to the encoded status of
         the command.  To avoid hard coding the exit status, we simply
	 loop until we find the right position.  */
      int exit_code;

      for (exit_code = e; e && WEXITSTATUS (e) != exit_code; e <<= 1)
	continue;
    }
  return e;
#else
  if (s == NULL)
    return 0;
  errno = ENOSYS;
  return -1;
#endif
}

int
_rename (const char * oldpath, const char * newpath)
{
#ifdef ARM_RDI_MONITOR
  int block[4];
  block[0] = (int) oldpath;
  block[1] = strlen(oldpath);
  block[2] = (int) newpath;
  block[3] = strlen(newpath);
  return wrap (do_AngelSWI (AngelSWI_Reason_Rename, block)) ? -1 : 0;
#else
  errno = ENOSYS;
  return -1;
#endif
}