libguile/rw.c

   1 /*      Copyright (C) 2001, 2006, 2009, 2011 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 License
   5  * as published by the Free Software Foundation; either version 3 of
   6  * the License, or (at your option) any later version.
   7  *
   8  * This library is distributed in the hope that it will be useful, but
   9  * 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., 51 Franklin Street, Fifth Floor, Boston, MA
  16  * 02110-1301 USA
  17  */
  18
  19 \f
  20
  21 /* This is the C part of the (ice-9 rw) module.  */
  22
  23 #ifdef HAVE_CONFIG_H
  24 #  include <config.h>
  25 #endif
  26
  27 #include <errno.h>
  28 #include <string.h>
  29
  30 #include "libguile/_scm.h"
  31 #include "libguile/fports.h"
  32 #include "libguile/ports.h"
  33 #include "libguile/root.h"
  34 #include "libguile/rw.h"
  35 #include "libguile/strings.h"
  36 #include "libguile/validate.h"
  37 #include "libguile/modules.h"
  38 #include "libguile/strports.h"
  39
  40 #ifdef HAVE_UNISTD_H
  41 #include <unistd.h>
  42 #endif
  43 #ifdef HAVE_IO_H
  44 #include <io.h>
  45 #endif
  46
  47 \f
  48
  49 #if defined (EAGAIN)
  50 #define SCM_MAYBE_EAGAIN || errno == EAGAIN
  51 #else
  52 #define SCM_MAYBE_EAGAIN
  53 #endif
  54
  55 #if defined (EWOULDBLOCK)
  56 #define SCM_MAYBE_EWOULDBLOCK || errno == EWOULDBLOCK
  57 #else
  58 #define SCM_MAYBE_EWOULDBLOCK
  59 #endif
  60
  61 /* MAYBE there is EAGAIN way of defining this macro but now I EWOULDBLOCK.  */
  62 #define SCM_EBLOCK(errno) \
  63    (0 SCM_MAYBE_EAGAIN SCM_MAYBE_EWOULDBLOCK)
  64
  65 SCM_DEFINE (scm_read_string_x_partial, "read-string!/partial", 1, 3, 0,
  66             (SCM str, SCM port_or_fdes, SCM start, SCM end),
  67             "Read characters from a port or file descriptor into a\n"
  68             "string @var{str}.  A port must have an underlying file\n"
  69             "descriptor --- a so-called fport.  This procedure is\n"
  70             "scsh-compatible and can efficiently read large strings.\n"
  71             "It will:\n\n"
  72             "@itemize\n"
  73             "@item\n"
  74             "attempt to fill the entire string, unless the @var{start}\n"
  75             "and/or @var{end} arguments are supplied.  i.e., @var{start}\n"
  76             "defaults to 0 and @var{end} defaults to\n"
  77             "@code{(string-length str)}\n"
  78             "@item\n"
  79             "use the current input port if @var{port_or_fdes} is not\n"
  80             "supplied.\n"
  81             "@item\n"
  82             "return fewer than the requested number of characters in some\n"
  83             "cases, e.g., on end of file, if interrupted by a signal, or if\n"
  84             "not all the characters are immediately available.\n"
  85             "@item\n"
  86             "wait indefinitely for some input if no characters are\n"
  87             "currently available,\n"
  88             "unless the port is in non-blocking mode.\n"
  89             "@item\n"
  90             "read characters from the port's input buffers if available,\n"
  91             "instead from the underlying file descriptor.\n"
  92             "@item\n"
  93             "return @code{#f} if end-of-file is encountered before reading\n"
  94             "any characters, otherwise return the number of characters\n"
  95             "read.\n"
  96             "@item\n"
  97             "return 0 if the port is in non-blocking mode and no characters\n"
  98             "are immediately available.\n"
  99             "@item\n"
 100             "return 0 if the request is for 0 bytes, with no\n"
 101             "end-of-file check.\n"
 102             "@end itemize")
 103 #define FUNC_NAME s_scm_read_string_x_partial
 104 {
 105   char *dest;
 106   size_t offset;
 107   long read_len;
 108   long chars_read = 0;
 109   int fdes;
 110
 111   {
 112     size_t last;
 113
 114     SCM_VALIDATE_STRING (1, str);
 115     scm_i_get_substring_spec (scm_i_string_length (str),
 116                               start, &offset, end, &last);
 117     read_len = last - offset;
 118   }
 119
 120   if (scm_is_integer (port_or_fdes))
 121     fdes = scm_to_int (port_or_fdes);
 122   else
 123     {
 124       SCM port = (SCM_UNBNDP (port_or_fdes)?
 125                   scm_current_input_port () : 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       str = scm_i_string_start_writing (str);
 135       dest = scm_i_string_writable_chars (str) + offset;
 136       chars_read = scm_take_from_input_buffers (port, dest, read_len);
 137       scm_i_string_stop_writing ();
 138       fdes = SCM_FPORT_FDES (port);
 139     }
 140
 141   if (chars_read == 0 && read_len > 0) /* don't confuse read_len == 0 with
 142                                           EOF.  */
 143     {
 144       str = scm_i_string_start_writing (str);
 145       dest = scm_i_string_writable_chars (str) + offset;
 146       SCM_SYSCALL (chars_read = read (fdes, dest, read_len));
 147       scm_i_string_stop_writing ();
 148       if (chars_read == -1)
 149         {
 150           if (SCM_EBLOCK (errno))
 151             chars_read = 0;
 152           else
 153             SCM_SYSERROR;
 154         }
 155       else if (chars_read == 0)
 156         {
 157           scm_remember_upto_here_1 (str);
 158           return SCM_BOOL_F;
 159         }
 160     }
 161
 162   scm_remember_upto_here_1 (str);
 163   return scm_from_long (chars_read);
 164 }
 165 #undef FUNC_NAME
 166
 167 SCM_DEFINE (scm_write_string_partial, "write-string/partial", 1, 3, 0,
 168             (SCM str, SCM port_or_fdes, SCM start, SCM end),
 169             "Write characters from a string @var{str} to a port or file\n"
 170             "descriptor.  A port must have an underlying file descriptor\n"
 171             "--- a so-called fport.  This procedure is\n"
 172             "scsh-compatible and can efficiently write large strings.\n"
 173             "It will:\n\n"
 174             "@itemize\n"
 175             "@item\n"
 176             "attempt to write the entire string, unless the @var{start}\n"
 177             "and/or @var{end} arguments are supplied.  i.e., @var{start}\n"
 178             "defaults to 0 and @var{end} defaults to\n"
 179             "@code{(string-length str)}\n"
 180             "@item\n"
 181             "use the current output port if @var{port_of_fdes} is not\n"
 182             "supplied.\n"
 183             "@item\n"
 184             "in the case of a buffered port, store the characters in the\n"
 185             "port's output buffer, if all will fit.  If they will not fit\n"
 186             "then any existing buffered characters will be flushed\n"
 187             "before attempting\n"
 188             "to write the new characters directly to the underlying file\n"
 189             "descriptor.  If the port is in non-blocking mode and\n"
 190             "buffered characters can not be flushed immediately, then an\n"
 191             "@code{EAGAIN} system-error exception will be raised (Note:\n"
 192             "scsh does not support the use of non-blocking buffered ports.)\n"
 193             "@item\n"
 194             "write fewer than the requested number of\n"
 195             "characters in some cases, e.g., if interrupted by a signal or\n"
 196             "if not all of the output can be accepted immediately.\n"
 197             "@item\n"
 198             "wait indefinitely for at least one character\n"
 199             "from @var{str} to be accepted by the port, unless the port is\n"
 200             "in non-blocking mode.\n"
 201             "@item\n"
 202             "return the number of characters accepted by the port.\n"
 203             "@item\n"
 204             "return 0 if the port is in non-blocking mode and can not accept\n"
 205             "at least one character from @var{str} immediately\n"
 206             "@item\n"
 207             "return 0 immediately if the request size is 0 bytes.\n"
 208             "@end itemize")
 209 #define FUNC_NAME s_scm_write_string_partial
 210 {
 211   const char *src;
 212   scm_t_off write_len;
 213   int fdes;
 214
 215   {
 216     size_t offset;
 217     size_t last;
 218
 219     SCM_VALIDATE_STRING (1, str);
 220     src = scm_i_string_chars (str);
 221     scm_i_get_substring_spec (scm_i_string_length (str),
 222                               start, &offset, end, &last);
 223     src += offset;
 224     write_len = last - offset;
 225   }
 226
 227   if (write_len == 0)
 228     return SCM_INUM0;
 229
 230   if (scm_is_integer (port_or_fdes))
 231     fdes = scm_to_int (port_or_fdes);
 232   else
 233     {
 234       SCM port = (SCM_UNBNDP (port_or_fdes)?
 235                   scm_current_output_port () : port_or_fdes);
 236       scm_t_port *pt;
 237       scm_t_off space;
 238
 239       SCM_VALIDATE_OPFPORT (2, port);
 240       SCM_VALIDATE_OUTPUT_PORT (2, port);
 241       pt = SCM_PTAB_ENTRY (port);
 242       /* filling the last character in the buffer would require a flush.  */
 243       space = pt->write_end - pt->write_pos - 1;
 244       if (space >= write_len)
 245         {
 246           memcpy (pt->write_pos, src, write_len);
 247           pt->write_pos += write_len;
 248           return scm_from_long (write_len);
 249         }
 250       if (pt->write_pos > pt->write_buf)
 251         scm_flush_unlocked (port);
 252       fdes = SCM_FPORT_FDES (port);
 253     }
 254   {
 255     long rv;
 256
 257     SCM_SYSCALL (rv = write (fdes, src, write_len));
 258     if (rv == -1)
 259       {
 260         if (SCM_EBLOCK (errno))
 261           rv = 0;
 262         else
 263           SCM_SYSERROR;
 264       }
 265
 266     scm_remember_upto_here_1 (str);
 267     return scm_from_long (rv);
 268   }
 269 }
 270 #undef FUNC_NAME
 271
 272 SCM
 273 scm_init_rw_builtins ()
 274 {
 275 #include "libguile/rw.x"
 276
 277   return SCM_UNSPECIFIED;
 278 }
 279
 280 void
 281 scm_init_rw ()
 282 {
 283   scm_c_define_gsubr ("%init-rw-builtins", 0, 0, 0, scm_init_rw_builtins);
 284 }
 285
 286 /*
 287   Local Variables:
 288   c-file-style: "gnu"
 289   End:
 290 */