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sortix--sortix/libc/stdio/fread_unlocked.cpp
2014-11-26 23:34:14 +01:00

84 lines
2.5 KiB
C++

/*******************************************************************************
Copyright(C) Jonas 'Sortie' Termansen 2011, 2012, 2013, 2014.
This file is part of the Sortix C Library.
The Sortix C Library is free software: you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation, either version 3 of the License, or (at your
option) any later version.
The Sortix 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 Lesser General Public
License for more details.
You should have received a copy of the GNU Lesser General Public License
along with the Sortix C Library. If not, see <http://www.gnu.org/licenses/>.
stdio/fread_unlocked.cpp
Reads data from a FILE.
*******************************************************************************/
#include <sys/types.h>
#include <errno.h>
#include <limits.h>
#include <stdint.h>
#include <stdio.h>
extern "C"
size_t fread_unlocked(void* ptr,
size_t element_size,
size_t num_elements,
FILE* fp)
{
if ( !(fp->flags & _FILE_READABLE) )
return errno = EBADF, fp->flags |= _FILE_STATUS_ERROR, EOF;
unsigned char* buf = (unsigned char*) ptr;
size_t count = element_size * num_elements;
if ( fp->buffer_mode == _IONBF )
{
if ( !(fp->flags & _FILE_BUFFER_MODE_SET) )
if ( fsetdefaultbuf_unlocked(fp) != 0 )
return EOF;
if ( !fp->read_func )
return errno = EBADF, fp->flags |= _FILE_STATUS_ERROR, 0;
if ( fp->flags & _FILE_LAST_WRITE )
fflush_stop_writing_unlocked(fp);
fp->flags |= _FILE_LAST_READ;
fp->flags &= ~_FILE_STATUS_EOF;
size_t sofar = 0;
while ( sofar < count )
{
size_t request = count - sofar;
if ( (size_t) SSIZE_MAX < request )
request = SSIZE_MAX;
ssize_t amount = fp->read_func(fp->user, buf + sofar, request);
if ( amount < 0 )
return fp->flags |= _FILE_STATUS_ERROR, sofar / num_elements;
if ( amount == 0 )
return fp->flags |= _FILE_STATUS_EOF, sofar / num_elements;
sofar += amount;
}
return sofar / element_size;
}
for ( size_t n = 0; n < num_elements; n++ )
{
size_t offset = n * element_size;
for ( size_t i = 0; i < element_size; i++ )
{
int c = fgetc_unlocked(fp);
if ( c == EOF )
return n;
buf[offset + i] = (unsigned char) c;
}
}
return num_elements;
}