libguile/rw.c

   1 /*      Copyright (C) 2001 Free Software Foundation, Inc.
   2  *
   3  * This library is free software; you can redistribute it and/or
   4  * modify it under the terms of the GNU Lesser General Public
   5  * License as published by the Free Software Foundation; either
   6  * version 2.1 of the License, or (at your option) any later version.
   7  *
   8  * This library is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11  * Lesser General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU Lesser General Public
  14  * License along with this library; if not, write to the Free Software
  15  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
  16  */
  17
  18 \f
  19
  20 /* This is the C part of the (ice-9 rw) module.  */
  21
  22 #if HAVE_CONFIG_H
  23 #  include <config.h>
  24 #endif
  25
  26 #include <errno.h>
  27 #include <string.h>
  28
  29 #include "libguile/_scm.h"
  30 #include "libguile/fports.h"
  31 #include "libguile/ports.h"
  32 #include "libguile/root.h"
  33 #include "libguile/rw.h"
  34 #include "libguile/strings.h"
  35 #include "libguile/validate.h"
  36 #include "libguile/modules.h"
  37 #include "libguile/strports.h"
  38
  39 #ifdef HAVE_UNISTD_H
  40 #include <unistd.h>
  41 #endif
  42 #ifdef HAVE_IO_H
  43 #include <io.h>
  44 #endif
  45
  46 \f
  47
  48 #if defined (EAGAIN)
  49 #define SCM_MAYBE_EAGAIN || errno == EAGAIN
  50 #else
  51 #define SCM_MAYBE_EAGAIN
  52 #endif
  53
  54 #if defined (EWOULDBLOCK)
  55 #define SCM_MAYBE_EWOULDBLOCK || errno == EWOULDBLOCK
  56 #else
  57 #define SCM_MAYBE_EWOULDBLOCK
  58 #endif
  59
  60 /* MAYBE there is EAGAIN way of defining this macro but now I EWOULDBLOCK.  */
  61 #define SCM_EBLOCK(errno) \
  62    (0 SCM_MAYBE_EAGAIN SCM_MAYBE_EWOULDBLOCK)
  63
  64 SCM_DEFINE (scm_read_string_x_partial, "read-string!/partial", 1, 3, 0,
  65             (SCM str, SCM port_or_fdes, SCM start, SCM end),
  66             "Read characters from a port or file descriptor into a\n"
  67             "string @var{str}.  A port must have an underlying file\n"
  68             "descriptor --- a so-called fport.  This procedure is\n"
  69             "scsh-compatible and can efficiently read large strings.\n"
  70             "It will:\n\n"
  71             "@itemize\n"
  72             "@item\n"
  73             "attempt to fill the entire string, unless the @var{start}\n"
  74             "and/or @var{end} arguments are supplied.  i.e., @var{start}\n"
  75             "defaults to 0 and @var{end} defaults to\n"
  76             "@code{(string-length str)}\n"
  77             "@item\n"
  78             "use the current input port if @var{port_or_fdes} is not\n"
  79             "supplied.\n"
  80             "@item\n"
  81             "return fewer than the requested number of characters in some\n"
  82             "cases, e.g., on end of file, if interrupted by a signal, or if\n"
  83             "not all the characters are immediately available.\n"
  84             "@item\n"
  85             "wait indefinitely for some input if no characters are\n"
  86             "currently available,\n"
  87             "unless the port is in non-blocking mode.\n"
  88             "@item\n"
  89             "read characters from the port's input buffers if available,\n"
  90             "instead from the underlying file descriptor.\n"
  91             "@item\n"
  92             "return @code{#f} if end-of-file is encountered before reading\n"
  93             "any characters, otherwise return the number of characters\n"
  94             "read.\n"
  95             "@item\n"
  96             "return 0 if the port is in non-blocking mode and no characters\n"
  97             "are immediately available.\n"
  98             "@item\n"
  99             "return 0 if the request is for 0 bytes, with no\n"
 100             "end-of-file check.\n"
 101             "@end itemize")
 102 #define FUNC_NAME s_scm_read_string_x_partial
 103 {
 104   char *dest;
 105   long read_len;
 106   long chars_read = 0;
 107   int fdes;
 108
 109   {
 110     size_t offset;
 111     size_t last;
 112
 113     SCM_VALIDATE_STRING (1, str);
 114     dest = SCM_I_STRING_CHARS (str);
 115     scm_i_get_substring_spec (SCM_I_STRING_LENGTH (str),
 116                               start, &offset, end, &last);
 117     dest += offset;
 118     read_len = last - offset;
 119   }
 120
 121   if (scm_is_integer (port_or_fdes))
 122     fdes = scm_to_int (port_or_fdes);
 123   else
 124     {
 125       SCM port = SCM_UNBNDP (port_or_fdes) ? scm_cur_inp : port_or_fdes;
 126
 127       SCM_VALIDATE_OPFPORT (2, port);
 128       SCM_VALIDATE_INPUT_PORT (2, port);
 129
 130       /* if there's anything in the port buffers, use it, but then
 131          don't touch the file descriptor.  otherwise the
 132          "return immediately if something is available" rule may
 133          be violated.  */
 134       chars_read = scm_take_from_input_buffers (port, dest, read_len);
 135       fdes = SCM_FPORT_FDES (port);
 136     }
 137
 138   if (chars_read == 0 && read_len > 0) /* don't confuse read_len == 0 with
 139                                           EOF.  */
 140     {
 141       SCM_SYSCALL (chars_read = read (fdes, dest, read_len));
 142       if (chars_read == -1)
 143         {
 144           if (SCM_EBLOCK (errno))
 145             chars_read = 0;
 146           else
 147             SCM_SYSERROR;
 148         }
 149       else if (chars_read == 0)
 150         {
 151           scm_remember_upto_here_1 (str);
 152           return SCM_BOOL_F;
 153         }
 154     }
 155
 156   scm_remember_upto_here_1 (str);
 157   return scm_from_long (chars_read);
 158 }
 159 #undef FUNC_NAME
 160
 161 SCM_DEFINE (scm_write_string_partial, "write-string/partial", 1, 3, 0,
 162             (SCM str, SCM port_or_fdes, SCM start, SCM end),
 163             "Write characters from a string @var{str} to a port or file\n"
 164             "descriptor.  A port must have an underlying file descriptor\n"
 165             "--- a so-called fport.  This procedure is\n"
 166             "scsh-compatible and can efficiently write large strings.\n"
 167             "It will:\n\n"
 168             "@itemize\n"
 169             "@item\n"
 170             "attempt to write the entire string, unless the @var{start}\n"
 171             "and/or @var{end} arguments are supplied.  i.e., @var{start}\n"
 172             "defaults to 0 and @var{end} defaults to\n"
 173             "@code{(string-length str)}\n"
 174             "@item\n"
 175             "use the current output port if @var{port_of_fdes} is not\n"
 176             "supplied.\n"
 177             "@item\n"
 178             "in the case of a buffered port, store the characters in the\n"
 179             "port's output buffer, if all will fit.  If they will not fit\n"
 180             "then any existing buffered characters will be flushed\n"
 181             "before attempting\n"
 182             "to write the new characters directly to the underlying file\n"
 183             "descriptor.  If the port is in non-blocking mode and\n"
 184             "buffered characters can not be flushed immediately, then an\n"
 185             "@code{EAGAIN} system-error exception will be raised (Note:\n"
 186             "scsh does not support the use of non-blocking buffered ports.)\n"
 187             "@item\n"
 188             "write fewer than the requested number of\n"
 189             "characters in some cases, e.g., if interrupted by a signal or\n"
 190             "if not all of the output can be accepted immediately.\n"
 191             "@item\n"
 192             "wait indefinitely for at least one character\n"
 193             "from @var{str} to be accepted by the port, unless the port is\n"
 194             "in non-blocking mode.\n"
 195             "@item\n"
 196             "return the number of characters accepted by the port.\n"
 197             "@item\n"
 198             "return 0 if the port is in non-blocking mode and can not accept\n"
 199             "at least one character from @var{str} immediately\n"
 200             "@item\n"
 201             "return 0 immediately if the request size is 0 bytes.\n"
 202             "@end itemize")
 203 #define FUNC_NAME s_scm_write_string_partial
 204 {
 205   char *src;
 206   long write_len;
 207   int fdes;
 208
 209   {
 210     size_t offset;
 211     size_t last;
 212
 213     SCM_VALIDATE_STRING (1, str);
 214     src = SCM_I_STRING_CHARS (str);
 215     scm_i_get_substring_spec (SCM_I_STRING_LENGTH (str),
 216                               start, &offset, end, &last);
 217     src += offset;
 218     write_len = last - offset;
 219   }
 220
 221   if (write_len == 0)
 222     return SCM_INUM0;
 223
 224   if (scm_is_integer (port_or_fdes))
 225     fdes = scm_to_int (port_or_fdes);
 226   else
 227     {
 228       SCM port = SCM_UNBNDP (port_or_fdes) ? scm_cur_outp : port_or_fdes;
 229       scm_t_port *pt;
 230       off_t space;
 231
 232       SCM_VALIDATE_OPFPORT (2, port);
 233       SCM_VALIDATE_OUTPUT_PORT (2, port);
 234       pt = SCM_PTAB_ENTRY (port);
 235       /* filling the last character in the buffer would require a flush.  */
 236       space = pt->write_end - pt->write_pos - 1;
 237       if (space >= write_len)
 238         {
 239           memcpy (pt->write_pos, src, write_len);
 240           pt->write_pos += write_len;
 241           return scm_from_long (write_len);
 242         }
 243       if (pt->write_pos > pt->write_buf)
 244         scm_flush (port);
 245       fdes = SCM_FPORT_FDES (port);
 246     }
 247   {
 248     long rv;
 249
 250     SCM_SYSCALL (rv = write (fdes, src, write_len));
 251     if (rv == -1)
 252       {
 253         if (SCM_EBLOCK (errno))
 254           rv = 0;
 255         else
 256           SCM_SYSERROR;
 257       }
 258
 259     scm_remember_upto_here_1 (str);
 260     return scm_from_long (rv);
 261   }
 262 }
 263 #undef FUNC_NAME
 264
 265 SCM
 266 scm_init_rw_builtins ()
 267 {
 268 #include "libguile/rw.x"
 269
 270   return SCM_UNSPECIFIED;
 271 }
 272
 273 void
 274 scm_init_rw ()
 275 {
 276   scm_c_define_gsubr ("%init-rw-builtins", 0, 0, 0, scm_init_rw_builtins);
 277 }
 278
 279 /*
 280   Local Variables:
 281   c-file-style: "gnu"
 282   End:
 283 */