diff options
Diffstat (limited to 'stdio/fread.c')
| -rw-r--r-- | stdio/fread.c | 128 |
1 files changed, 128 insertions, 0 deletions
diff --git a/stdio/fread.c b/stdio/fread.c new file mode 100644 index 0000000000..347e8446e1 --- /dev/null +++ b/stdio/fread.c @@ -0,0 +1,128 @@ +/* Copyright (C) 1991, 1992 Free Software Foundation, Inc. +This file is part of the GNU C Library. + +The GNU C Library is free software; you can redistribute it and/or +modify it under the terms of the GNU Library General Public License as +published by the Free Software Foundation; either version 2 of the +License, or (at your option) any later version. + +The GNU C Library is distributed in the hope that it will be useful, +but WITHOUT ANY WARRANTY; without even the implied warranty of +MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU +Library General Public License for more details. + +You should have received a copy of the GNU Library General Public +License along with the GNU C Library; see the file COPYING.LIB. If +not, write to the Free Software Foundation, Inc., 675 Mass Ave, +Cambridge, MA 02139, USA. */ + +#include <ansidecl.h> +#include <errno.h> +#include <stdio.h> +#include <string.h> + + +#define default_func __default_room_functions.__input + +/* Read NMEMB chunks of SIZE bytes each from STREAM into P. */ +size_t +DEFUN(fread, (p, size, nmemb, stream), + PTR p AND size_t size AND size_t nmemb AND register FILE *stream) +{ + register char *ptr = (char *) p; + register size_t to_read = size * nmemb; + size_t bytes = to_read; + + if (!__validfp(stream) || !stream->__mode.__read) + { + errno = EINVAL; + return 0; + } + if (feof(stream) || ferror(stream)) + return 0; + if (p == NULL || to_read == 0) + return 0; + + if (!stream->__seen || stream->__buffer == NULL || stream->__pushed_back) + { + /* This stream has never been seen before, or it has a character + pushed back. Call __fillbf to deal with those cases. Life will + be simpler after this call. */ + int c = __fillbf(stream); + if (c == EOF) + return 0; + *ptr++ = c; + if (--to_read == 0) + return 1; + } + + read_from_buffer:; + if (stream->__bufp < stream->__get_limit) + { + /* First off, empty out the buffer. */ + register size_t copy = stream->__get_limit - stream->__bufp; + if (copy > to_read) + copy = to_read; + to_read -= copy; + if (copy > 20) + memcpy((PTR) ptr, (PTR) stream->__bufp, copy); + else + { + register size_t i; + for (i = 0; i < copy; ++i) + ptr[i] = stream->__bufp[i]; + } + stream->__bufp += copy; + if (to_read == 0) + return nmemb; + ptr += copy; + } + + /* Reading directly into the user's buffer doesn't help when + using a user-specified input buffer filling/expanding function, + so we don't do it in that case. */ + if (to_read >= stream->__bufsize && + stream->__room_funcs.__input == default_func && + stream->__offset == stream->__target) + { + /* Read directly into the user's buffer. */ + if (stream->__io_funcs.__read != NULL) + while (to_read > 0) + { + register int count; + count = (*stream->__io_funcs.__read)(stream->__cookie, + ptr, to_read); + if (count > 0) + { + to_read -= count; + stream->__offset += count; + stream->__target += count; + ptr += count; + } + else if (count == 0) + { + stream->__eof = 1; + break; + } + else + { + stream->__error = 1; + break; + } + } + else + stream->__eof = 1; + } + else + { + int c = __fillbf(stream); + if (c == EOF) + return (bytes - to_read) / size; + *ptr++ = (char) c; + --to_read; + if (to_read > 0) + goto read_from_buffer; + } + + return (bytes - to_read) / size; +} |