95 lines
3.0 KiB
C++
95 lines
3.0 KiB
C++
/******************************************************************************
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COPYRIGHT(C) JONAS 'SORTIE' TERMANSEN 2011.
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This file is part of Sortix.
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Sortix is free software: you can redistribute it and/or modify it under the
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terms of the GNU General Public License as published by the Free Software
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Foundation, either version 3 of the License, or (at your option) any later
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version.
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Sortix is distributed in the hope that it will be useful, but WITHOUT ANY
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WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
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details.
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You should have received a copy of the GNU General Public License along
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with Sortix. If not, see <http://www.gnu.org/licenses/>.
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filesystem.cpp
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Allows access to stored sequences of bytes in an orderly fashion.
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******************************************************************************/
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#include "platform.h"
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#include <libmaxsi/error.h>
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#include <libmaxsi/memory.h>
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#include <libmaxsi/string.h>
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#include "syscall.h"
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#include "process.h"
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#include "device.h"
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#include "directory.h"
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using namespace Maxsi;
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namespace Sortix
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{
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namespace Directory
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{
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int SysReadDirEnts(int fd, sortix_dirent* dirent, size_t size)
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{
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Process* process = CurrentProcess();
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Device* dev = process->descriptors.Get(fd);
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if ( !dev ) { Error::Set(Error::EBADF); return -1; }
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if ( !dev->IsType(Device::DIRECTORY) ) { Error::Set(Error::EBADF); return -1; }
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DevDirectory* dir = (DevDirectory*) dev;
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sortix_dirent* prev = NULL;
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while ( true )
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{
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// Check if we got enough bytes left to tell how many bytes we
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// actually needed.
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if ( size < sizeof(sortix_dirent) )
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{
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if ( prev ) { return 0; } // We did some work.
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Error::Set(Error::EINVAL); // Nope, userspace was cheap.
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return -1;
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}
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// Attempt to read into the space left, and if we managed to
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// read at least one record, just say we succeded. The user
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// space buffer is empty on the next call, so that'll probably
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// succeed. The directory read function will store the number of
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// bytes needed in the d_namelen variable and set errno to
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// EINVAL such that userspace knows we need a larger buffer.
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if ( dir->Read(dirent, size) ) { return (prev) ? 0 : -1; }
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// Insert the current dirent into the single-linked list for
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// easy iteration by userspace.
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prev->d_next = dirent;
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dirent->d_next = NULL;
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// Check for end-of-directory conditions. Signal to userspace
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// that we are done by giving them the empty filename.
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if ( dirent->d_namelen == 0 ) { return 0; }
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// Alright, we managed to read a dirent. Now let's try reading
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// another one (provide as many as we can).
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prev = dirent;
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size_t bytesused = sizeof(sortix_dirent) + dirent->d_namelen + 1;
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size -= bytesused;
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dirent = (sortix_dirent*) ( ((byte*) dirent) + bytesused );
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}
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}
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void Init()
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{
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Syscall::Register(SYSCALL_READDIRENTS, (void*) SysReadDirEnts);
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}
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}
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}
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