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[/] [openrisc/] [trunk/] [gnu-src/] [newlib-1.18.0/] [newlib/] [libc/] [stdio/] [fopencookie.c] - Rev 551
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/* Copyright (C) 2007 Eric Blake * Permission to use, copy, modify, and distribute this software * is freely granted, provided that this notice is preserved. */ /* FUNCTION <<fopencookie>>---open a stream with custom callbacks INDEX fopencookie ANSI_SYNOPSIS #include <stdio.h> FILE *fopencookie(const void *<[cookie]>, const char *<[mode]>, cookie_io_functions_t <[functions]>); DESCRIPTION <<fopencookie>> creates a <<FILE>> stream where I/O is performed using custom callbacks. The callbacks are registered via the structure: typedef ssize_t (*cookie_read_function_t)(void *_cookie, char *_buf, size_t _n); typedef ssize_t (*cookie_write_function_t)(void *_cookie, const char *_buf, size_t _n); typedef int (*cookie_seek_function_t)(void *_cookie, off_t *_off, int _whence); typedef int (*cookie_close_function_t)(void *_cookie); . typedef struct . { . cookie_read_function_t *read; . cookie_write_function_t *write; . cookie_seek_function_t *seek; . cookie_close_function_t *close; . } cookie_io_functions_t; The stream is opened with <[mode]> treated as in <<fopen>>. The callbacks <[functions.read]> and <[functions.write]> may only be NULL when <[mode]> does not require them. <[functions.read]> should return -1 on failure, or else the number of bytes read (0 on EOF). It is similar to <<read>>, except that <[cookie]> will be passed as the first argument. <[functions.write]> should return -1 on failure, or else the number of bytes written. It is similar to <<write>>, except that <[cookie]> will be passed as the first argument. <[functions.seek]> should return -1 on failure, and 0 on success, with *<[_off]> set to the current file position. It is a cross between <<lseek>> and <<fseek>>, with the <[_whence]> argument interpreted in the same manner. A NULL <[functions.seek]> makes the stream behave similarly to a pipe in relation to stdio functions that require positioning. <[functions.close]> should return -1 on failure, or 0 on success. It is similar to <<close>>, except that <[cookie]> will be passed as the first argument. A NULL <[functions.close]> merely flushes all data then lets <<fclose>> succeed. A failed close will still invalidate the stream. Read and write I/O functions are allowed to change the underlying buffer on fully buffered or line buffered streams by calling <<setvbuf>>. They are also not required to completely fill or empty the buffer. They are not, however, allowed to change streams from unbuffered to buffered or to change the state of the line buffering flag. They must also be prepared to have read or write calls occur on buffers other than the one most recently specified. RETURNS The return value is an open FILE pointer on success. On error, <<NULL>> is returned, and <<errno>> will be set to EINVAL if a function pointer is missing or <[mode]> is invalid, ENOMEM if the stream cannot be created, or EMFILE if too many streams are already open. PORTABILITY This function is a newlib extension, copying the prototype from Linux. It is not portable. See also the <<funopen>> interface from BSD. Supporting OS subroutines required: <<sbrk>>. */ #include <stdio.h> #include <errno.h> #include <sys/lock.h> #include "local.h" typedef struct fccookie { void *cookie; FILE *fp; cookie_read_function_t *readfn; cookie_write_function_t *writefn; cookie_seek_function_t *seekfn; cookie_close_function_t *closefn; } fccookie; static _READ_WRITE_RETURN_TYPE _DEFUN(fcreader, (ptr, cookie, buf, n), struct _reent *ptr _AND void *cookie _AND char *buf _AND int n) { int result; fccookie *c = (fccookie *) cookie; errno = 0; if ((result = c->readfn (c->cookie, buf, n)) < 0 && errno) ptr->_errno = errno; return result; } static _READ_WRITE_RETURN_TYPE _DEFUN(fcwriter, (ptr, cookie, buf, n), struct _reent *ptr _AND void *cookie _AND const char *buf _AND int n) { int result; fccookie *c = (fccookie *) cookie; if (c->fp->_flags & __SAPP && c->fp->_seek) { #ifdef __LARGE64_FILES c->fp->_seek64 (ptr, cookie, 0, SEEK_END); #else c->fp->_seek (ptr, cookie, 0, SEEK_END); #endif } errno = 0; if ((result = c->writefn (c->cookie, buf, n)) < 0 && errno) ptr->_errno = errno; return result; } static _fpos_t _DEFUN(fcseeker, (ptr, cookie, pos, whence), struct _reent *ptr _AND void *cookie _AND _fpos_t pos _AND int whence) { fccookie *c = (fccookie *) cookie; #ifndef __LARGE64_FILES off_t offset = (off_t) pos; #else /* __LARGE64_FILES */ _off64_t offset = (_off64_t) pos; #endif /* __LARGE64_FILES */ errno = 0; if (c->seekfn (c->cookie, &offset, whence) < 0 && errno) ptr->_errno = errno; #ifdef __LARGE64_FILES else if ((_fpos_t)offset != offset) { ptr->_errno = EOVERFLOW; offset = -1; } #endif /* __LARGE64_FILES */ return (_fpos_t) offset; } #ifdef __LARGE64_FILES static _fpos64_t _DEFUN(fcseeker64, (ptr, cookie, pos, whence), struct _reent *ptr _AND void *cookie _AND _fpos64_t pos _AND int whence) { _off64_t offset; fccookie *c = (fccookie *) cookie; errno = 0; if (c->seekfn (c->cookie, &offset, whence) < 0 && errno) ptr->_errno = errno; return (_fpos64_t) offset; } #endif /* __LARGE64_FILES */ static int _DEFUN(fccloser, (ptr, cookie), struct _reent *ptr _AND void *cookie) { int result = 0; fccookie *c = (fccookie *) cookie; if (c->closefn) { errno = 0; if ((result = c->closefn (c->cookie)) < 0 && errno) ptr->_errno = errno; } _free_r (ptr, c); return result; } FILE * _DEFUN(_fopencookie_r, (ptr, cookie, mode, functions), struct _reent *ptr _AND void *cookie _AND const char *mode _AND cookie_io_functions_t functions) { FILE *fp; fccookie *c; int flags; int dummy; if ((flags = __sflags (ptr, mode, &dummy)) == 0) return NULL; if (((flags & (__SRD | __SRW)) && !functions.read) || ((flags & (__SWR | __SRW)) && !functions.write)) { ptr->_errno = EINVAL; return NULL; } if ((fp = __sfp (ptr)) == NULL) return NULL; if ((c = (fccookie *) _malloc_r (ptr, sizeof *c)) == NULL) { __sfp_lock_acquire (); fp->_flags = 0; /* release */ #ifndef __SINGLE_THREAD__ __lock_close_recursive (fp->_lock); #endif __sfp_lock_release (); return NULL; } _flockfile (fp); fp->_file = -1; fp->_flags = flags; c->cookie = cookie; c->fp = fp; fp->_cookie = c; c->readfn = functions.read; fp->_read = fcreader; c->writefn = functions.write; fp->_write = fcwriter; c->seekfn = functions.seek; fp->_seek = functions.seek ? fcseeker : NULL; #ifdef __LARGE64_FILES fp->_seek64 = functions.seek ? fcseeker64 : NULL; fp->_flags |= __SL64; #endif c->closefn = functions.close; fp->_close = fccloser; _funlockfile (fp); return fp; } #ifndef _REENT_ONLY FILE * _DEFUN(fopencookie, (cookie, mode, functions), void *cookie _AND const char *mode _AND cookie_io_functions_t functions) { return _fopencookie_r (_REENT, cookie, mode, functions); } #endif /* !_REENT_ONLY */
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