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sortix--sortix/libc/fdio.c

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/*******************************************************************************
Copyright(C) Jonas 'Sortie' Termansen 2011, 2012, 2013.
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/>.
fdio.c
Handles the file descriptor backend for the FILE* API.
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*******************************************************************************/
#include <sys/stat.h>
#include <errno.h>
#include <fcntl.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include "fdio.h"
const int FDIO_WRITING = (1<<0);
const int FDIO_READING = (1<<1);
const int FDIO_APPEND = (1<<2);
const int FDIO_ERROR = (1<<3);
const int FDIO_EOF = (1<<4);
typedef struct fdio_struct
{
int flags;
int fd;
} fdio_t;
static int fdio_reopen(void* user, const char* mode)
{
(void) user;
(void) mode;
// TODO: Unfortunately, we don't support this yet. Note that we don't really
// have to support this according to POSIX - but it'd be nicer to push this
// restriction into the kernel and argue it's a security problem "What? No
// you can't make this read-only descriptor readable!".
return errno = ENOTSUP, -1;
}
static size_t fdio_read(void* ptr, size_t size, size_t nmemb, void* user)
{
uint8_t* buf = (uint8_t*) ptr;
fdio_t* fdio = (fdio_t*) user;
if ( !(fdio->flags & FDIO_READING) ) { errno = EBADF; return 0; }
size_t sofar = 0;
size_t total = size * nmemb;
while ( sofar < total )
{
ssize_t numbytes = read(fdio->fd, buf + sofar, total - sofar);
if ( numbytes < 0 ) { fdio->flags |= FDIO_ERROR; break; }
if ( numbytes == 0 ) { fdio->flags |= FDIO_EOF; break; }
// TODO: Is this a bug? Looks like one, but perhaps this is needed when
// reading from line-buffered terminals.
return numbytes / size;
sofar += numbytes;
}
return sofar / size;
}
static size_t fdio_write(const void* ptr, size_t size, size_t nmemb, void* user)
{
const uint8_t* buf = (const uint8_t*) ptr;
fdio_t* fdio = (fdio_t*) user;
if ( !(fdio->flags & FDIO_WRITING) ) { errno = EBADF; return 0; }
size_t sofar = 0;
size_t total = size * nmemb;
while ( sofar < total )
{
ssize_t numbytes = write(fdio->fd, buf + sofar, total - sofar);
if ( numbytes < 0 ) { fdio->flags |= FDIO_ERROR; break; }
if ( numbytes == 0 ) { fdio->flags |= FDIO_EOF; break; }
sofar += numbytes;
}
return sofar / size;
}
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static int fdio_seek(void* user, off_t offset, int whence)
{
fdio_t* fdio = (fdio_t*) user;
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return 0 <= lseek(fdio->fd, offset, whence) ? 0 : -1;
}
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static off_t fdio_tell(void* user)
{
fdio_t* fdio = (fdio_t*) user;
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return lseek(fdio->fd, 0, SEEK_CUR);;
}
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static void fdio_seterr(void* user)
{
fdio_t* fdio = (fdio_t*) user;
fdio->flags |= FDIO_ERROR;
}
static void fdio_clearerr(void* user)
{
fdio_t* fdio = (fdio_t*) user;
fdio->flags &= ~FDIO_ERROR;
}
static int fdio_eof(void* user)
{
fdio_t* fdio = (fdio_t*) user;
return fdio->flags & FDIO_EOF;
}
static int fdio_error(void* user)
{
fdio_t* fdio = (fdio_t*) user;
return fdio->flags & FDIO_ERROR;
}
static int fdio_fileno(void* user)
{
fdio_t* fdio = (fdio_t*) user;
return fdio->fd;
}
static int fdio_close(void* user)
{
fdio_t* fdio = (fdio_t*) user;
int result = close(fdio->fd);
free(fdio);
return result;
}
int fdio_open_descriptor(const char* path, const char* mode)
{
int omode = 0;
int oflags = 0;
char c;
// TODO: This is too hacky and a little buggy.
const char* origmode = mode;
while ( (c = *mode++) )
switch ( c )
{
case 'r': omode = O_RDONLY; break;
case 'a': oflags |= O_APPEND; /* fall-through */
case 'w': omode = O_WRONLY; oflags |= O_CREAT | O_TRUNC; break;
case '+':
omode = O_RDWR;
break;
case 'b': break;
case 't': break;
default:
fprintf(stderr, "Unsupported fopen mode: '%s'\n", origmode);
errno = EINVAL;
return -1;
}
return open(path, omode | oflags, 0666);
}
int fdio_install_fd(FILE* fp, int fd, const char* mode)
{
fdio_t* fdio = (fdio_t*) calloc(1, sizeof(fdio_t));
if ( !fdio )
return 0;
fdio->fd = fd;
char c;
// TODO: This is too hacky and a little buggy.
while ( ( c = *mode++ ) )
{
switch ( c )
{
case 'r': fdio->flags |= FDIO_READING; break;
case 'w': fdio->flags |= FDIO_WRITING; break;
case '+': fdio->flags |= FDIO_READING | FDIO_WRITING; break;
case 'a': fdio->flags |= FDIO_WRITING | FDIO_APPEND; break;
case 't': break;
case 'b': break;
default: errno = EINVAL; free(fdio); return 0;
}
}
struct stat st;
if ( !fstat(fd, &st) && fdio->flags & FDIO_WRITING && S_ISDIR(st.st_mode) )
return free(fdio), errno = EISDIR, 0;
fp->user = fdio;
fp->reopen_func = fdio_reopen;
fp->read_func = fdio_read;
fp->write_func = fdio_write;
fp->seek_func = fdio_seek;
fp->tell_func = fdio_tell;
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fp->seterr_func = fdio_seterr;
fp->clearerr_func = fdio_clearerr;
fp->eof_func = fdio_eof;
fp->error_func = fdio_error;
fp->fileno_func = fdio_fileno;
fp->close_func = fdio_close;
if ( lseek(fd, 0, SEEK_CUR) < 0 && errno == ESPIPE )
fp->flags |= _FILE_STREAM;
return 1;
}
int fdio_install_path(FILE* fp, const char* path, const char* mode)
{
int fd = fdio_open_descriptor(path, mode);
if ( fd < 0 )
return 0;
if ( !fdio_install_fd(fp, fd, mode) )
return close(fd), 0;
return 1;
}
FILE* fdio_new_fd(int fd, const char* mode)
{
FILE* fp = fnewfile();
if ( !fp )
return NULL;
if ( !fdio_install_fd(fp, fd, mode) )
return fclose(fp), (FILE*) NULL;
return fp;
}
FILE* fdio_new_path(const char* path, const char* mode)
{
FILE* fp = fnewfile();
if ( !fp )
return NULL;
if ( !fdio_install_path(fp, path, mode) )
return fclose(fp), (FILE*) NULL;
return fp;
}
FILE* fdopen(int fd, const char* mode)
{
return fdio_new_fd(fd, mode);
}
FILE* fopen(const char* path, const char* mode)
{
return fdio_new_path(path, mode);
}