libc/stdio/_READ.c

   1 /* Copyright (C) 2004       Manuel Novoa III    <mjn3@codepoet.org>
   2  *
   3  * GNU Library General Public License (LGPL) version 2 or later.
   4  *
   5  * Dedicated to Toni.  See uClibc/DEDICATION.mjn3 for details.
   6  */
   7
   8 #include "_stdio.h"
   9
  10
  11 /* Given a reading stream without its end-of-file indicator set and
  12  * with no buffered input or ungots, read at most 'bufsize' bytes
  13  * into 'buf' (which may be the stream's __bufstart).
  14  * If a read error occurs, set the stream's error indicator.
  15  * If EOF is encountered, set the stream's end-of-file indicator.
  16  *
  17  * Returns the number of bytes read, even in EOF and error cases.
  18  *
  19  * Notes:
  20  *   Calling with bufsize == 0 is NOT permitted (unlike __stdio_WRITE).
  21  *   NOT THREADSAFE!  Assumes stream already locked if necessary.
  22  */
  23
  24 size_t attribute_hidden __stdio_READ(register FILE *stream,
  25                                         unsigned char *buf, size_t bufsize)
  26 {
  27         ssize_t rv = 0;
  28
  29         __STDIO_STREAM_VALIDATE(stream);
  30         assert(stream->__filedes >= -2);
  31         assert(__STDIO_STREAM_IS_READING(stream));
  32         assert(!__STDIO_STREAM_BUFFER_RAVAIL(stream)); /* Buffer must be empty. */
  33         assert(!(stream->__modeflags & __FLAG_UNGOT));
  34         assert(bufsize);
  35
  36         if (!__FEOF_UNLOCKED(stream)) {
  37                 if (bufsize > SSIZE_MAX) {
  38                         bufsize = SSIZE_MAX;
  39                 }
  40
  41 /*      RETRY: */
  42                 if ((rv = __READ(stream, (char *) buf, bufsize)) <= 0) {
  43                         if (rv == 0) {
  44                                 __STDIO_STREAM_SET_EOF(stream);
  45                         } else {
  46 /*                              if (errno == EINTR) goto RETRY; */
  47                                 __STDIO_STREAM_SET_ERROR(stream);
  48                                 rv = 0;
  49                         }
  50 #ifdef __UCLIBC_HAS_GLIBC_CUSTOM_STREAMS__
  51                 } else {
  52                         assert(rv <= bufsize);
  53                         if (rv > bufsize) {     /* Read more than bufsize! */
  54                                 abort();
  55                         }
  56 #endif
  57                 }
  58         }
  59
  60         return rv;
  61 }