libguile/rw.c

   1 /*      Copyright (C) 2001, 2006 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  16  */
  17
  18 \f
  19
  20 /* This is the C part of the (ice-9 rw) module.  */
  21
  22 #ifdef 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   size_t offset;
 106   long read_len;
 107   long chars_read = 0;
 108   int fdes;
 109
 110   {
 111     size_t last;
 112
 113     SCM_VALIDATE_STRING (1, str);
 114     scm_i_get_substring_spec (scm_i_string_length (str),
 115                               start, &offset, end, &last);
 116     read_len = last - offset;
 117   }
 118
 119   if (scm_is_integer (port_or_fdes))
 120     fdes = scm_to_int (port_or_fdes);
 121   else
 122     {
 123       SCM port = (SCM_UNBNDP (port_or_fdes)?
 124                   scm_current_input_port () : port_or_fdes);
 125
 126       SCM_VALIDATE_OPFPORT (2, port);
 127       SCM_VALIDATE_INPUT_PORT (2, port);
 128
 129       /* if there's anything in the port buffers, use it, but then
 130          don't touch the file descriptor.  otherwise the
 131          "return immediately if something is available" rule may
 132          be violated.  */
 133       dest = scm_i_string_writable_chars (str) + offset;
 134       chars_read = scm_take_from_input_buffers (port, dest, read_len);
 135       scm_i_string_stop_writing ();
 136       fdes = SCM_FPORT_FDES (port);
 137     }
 138
 139   if (chars_read == 0 && read_len > 0) /* don't confuse read_len == 0 with
 140                                           EOF.  */
 141     {
 142       dest = scm_i_string_writable_chars (str) + offset;
 143       SCM_SYSCALL (chars_read = read (fdes, dest, read_len));
 144       scm_i_string_stop_writing ();
 145       if (chars_read == -1)
 146         {
 147           if (SCM_EBLOCK (errno))
 148             chars_read = 0;
 149           else
 150             SCM_SYSERROR;
 151         }
 152       else if (chars_read == 0)
 153         {
 154           scm_remember_upto_here_1 (str);
 155           return SCM_BOOL_F;
 156         }
 157     }
 158
 159   scm_remember_upto_here_1 (str);
 160   return scm_from_long (chars_read);
 161 }
 162 #undef FUNC_NAME
 163
 164 SCM_DEFINE (scm_write_string_partial, "write-string/partial", 1, 3, 0,
 165             (SCM str, SCM port_or_fdes, SCM start, SCM end),
 166             "Write characters from a string @var{str} to a port or file\n"
 167             "descriptor.  A port must have an underlying file descriptor\n"
 168             "--- a so-called fport.  This procedure is\n"
 169             "scsh-compatible and can efficiently write large strings.\n"
 170             "It will:\n\n"
 171             "@itemize\n"
 172             "@item\n"
 173             "attempt to write the entire string, unless the @var{start}\n"
 174             "and/or @var{end} arguments are supplied.  i.e., @var{start}\n"
 175             "defaults to 0 and @var{end} defaults to\n"
 176             "@code{(string-length str)}\n"
 177             "@item\n"
 178             "use the current output port if @var{port_of_fdes} is not\n"
 179             "supplied.\n"
 180             "@item\n"
 181             "in the case of a buffered port, store the characters in the\n"
 182             "port's output buffer, if all will fit.  If they will not fit\n"
 183             "then any existing buffered characters will be flushed\n"
 184             "before attempting\n"
 185             "to write the new characters directly to the underlying file\n"
 186             "descriptor.  If the port is in non-blocking mode and\n"
 187             "buffered characters can not be flushed immediately, then an\n"
 188             "@code{EAGAIN} system-error exception will be raised (Note:\n"
 189             "scsh does not support the use of non-blocking buffered ports.)\n"
 190             "@item\n"
 191             "write fewer than the requested number of\n"
 192             "characters in some cases, e.g., if interrupted by a signal or\n"
 193             "if not all of the output can be accepted immediately.\n"
 194             "@item\n"
 195             "wait indefinitely for at least one character\n"
 196             "from @var{str} to be accepted by the port, unless the port is\n"
 197             "in non-blocking mode.\n"
 198             "@item\n"
 199             "return the number of characters accepted by the port.\n"
 200             "@item\n"
 201             "return 0 if the port is in non-blocking mode and can not accept\n"
 202             "at least one character from @var{str} immediately\n"
 203             "@item\n"
 204             "return 0 immediately if the request size is 0 bytes.\n"
 205             "@end itemize")
 206 #define FUNC_NAME s_scm_write_string_partial
 207 {
 208   const char *src;
 209   long write_len;
 210   int fdes;
 211
 212   {
 213     size_t offset;
 214     size_t last;
 215
 216     SCM_VALIDATE_STRING (1, str);
 217     src = scm_i_string_chars (str);
 218     scm_i_get_substring_spec (scm_i_string_length (str),
 219                               start, &offset, end, &last);
 220     src += offset;
 221     write_len = last - offset;
 222   }
 223
 224   if (write_len == 0)
 225     return SCM_INUM0;
 226
 227   if (scm_is_integer (port_or_fdes))
 228     fdes = scm_to_int (port_or_fdes);
 229   else
 230     {
 231       SCM port = (SCM_UNBNDP (port_or_fdes)?
 232                   scm_current_output_port () : port_or_fdes);
 233       scm_t_port *pt;
 234       off_t space;
 235
 236       SCM_VALIDATE_OPFPORT (2, port);
 237       SCM_VALIDATE_OUTPUT_PORT (2, port);
 238       pt = SCM_PTAB_ENTRY (port);
 239       /* filling the last character in the buffer would require a flush.  */
 240       space = pt->write_end - pt->write_pos - 1;
 241       if (space >= write_len)
 242         {
 243           memcpy (pt->write_pos, src, write_len);
 244           pt->write_pos += write_len;
 245           return scm_from_long (write_len);
 246         }
 247       if (pt->write_pos > pt->write_buf)
 248         scm_flush (port);
 249       fdes = SCM_FPORT_FDES (port);
 250     }
 251   {
 252     long rv;
 253
 254     SCM_SYSCALL (rv = write (fdes, src, write_len));
 255     if (rv == -1)
 256       {
 257         if (SCM_EBLOCK (errno))
 258           rv = 0;
 259         else
 260           SCM_SYSERROR;
 261       }
 262
 263     scm_remember_upto_here_1 (str);
 264     return scm_from_long (rv);
 265   }
 266 }
 267 #undef FUNC_NAME
 268
 269 SCM
 270 scm_init_rw_builtins ()
 271 {
 272 #include "libguile/rw.x"
 273
 274   return SCM_UNSPECIFIED;
 275 }
 276
 277 void
 278 scm_init_rw ()
 279 {
 280   scm_c_define_gsubr ("%init-rw-builtins", 0, 0, 0, scm_init_rw_builtins);
 281 }
 282
 283 /*
 284   Local Variables:
 285   c-file-style: "gnu"
 286   End:
 287 */