diff options
Diffstat (limited to 'stdio/memstream.c')
| -rw-r--r-- | stdio/memstream.c | 177 |
1 files changed, 177 insertions, 0 deletions
diff --git a/stdio/memstream.c b/stdio/memstream.c new file mode 100644 index 0000000000..704eca53b3 --- /dev/null +++ b/stdio/memstream.c @@ -0,0 +1,177 @@ +/* Copyright (C) 1991, 1992, 1994 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 <stdio.h> +#include <stdlib.h> +#include <string.h> + +struct memstream_info + { + char **buffer; + size_t *bufsize; + }; + +/* Enlarge STREAM's buffer. */ +static void +DEFUN(enlarge_buffer, (stream, c), + register FILE *stream AND int c) +{ + struct memstream_info *info = (struct memstream_info *) stream->__cookie; + size_t need; + + if (stream->__put_limit != stream->__buffer) + /* Record how much has actually been written into the buffer. */ + *info->bufsize = stream->__bufp - stream->__buffer; + + if (stream->__target != -1 + && stream->__target > *info->bufsize) + /* Our target (where the buffer maps to) is always zero except when + the user just did a SEEK_END fseek. If he sought within the + buffer, we need do nothing and will zero the target below. If he + sought past the end of the object, grow and zero-fill the buffer + up to the target address. */ + need = stream->__target; + else + need = *info->bufsize; + + /* We always need an extra character in the buffer. Either we are + writing C, or we are flushing and need to write a NUL terminator. */ + ++need; + + if (stream->__bufsize < need) + { + /* Enlarge the buffer. */ + char *newbuf; + size_t newsize; + if (stream->__bufsize * 2 < need) + newsize = need; + else + newsize = stream->__bufsize * 2; + newbuf = (char *) realloc ((PTR) stream->__buffer, newsize); + if (newbuf == NULL) + { + stream->__error = 1; + return; + } + *info->buffer = stream->__buffer = newbuf; + stream->__bufsize = newsize; + } + + stream->__target = stream->__offset = 0; + stream->__get_limit = stream->__bufp = stream->__buffer + *info->bufsize; + stream->__put_limit = stream->__buffer + stream->__bufsize; + + need -= stream->__bufp - stream->__buffer + 1; + if (need > 0) + { + /* We are extending the buffer after an fseek; zero-fill new space. */ + bzero (stream->__bufp, need); + stream->__bufp += need; + } + + if (c != EOF) + *stream->__bufp++ = (unsigned char) c; + else + *stream->__bufp = '\0'; +} + +/* Seek function for memstreams. + There is no external state to munge. */ + +static int +DEFUN(seek, (cookie, pos, whence), + PTR cookie AND fpos_t *pos AND int whence) +{ + switch (whence) + { + case SEEK_SET: + case SEEK_CUR: + return 0; + + case SEEK_END: + /* Return the position relative to the end of the object. + fseek has just flushed us, so the info is consistent. */ + *pos += *((struct memstream_info *) cookie)->bufsize; + return 0; + + default: + __libc_fatal ("memstream::seek called with bogus WHENCE\n"); + return -1; + } +} + +static int +DEFUN(free_info, (cookie), PTR cookie) +{ +#if 0 + struct memstream_info *info = (struct memstream_info *) cookie; + char *buf; + + buf = (char *) realloc ((PTR) *info->buffer, *info->bufsize); + if (buf != NULL) + *info->buffer = buf; +#endif + + free (cookie); + + return 0; +} + +/* Open a stream that writes into a malloc'd buffer that is expanded as + necessary. *BUFLOC and *SIZELOC are updated with the buffer's location + and the number of characters written on fflush or fclose. */ +FILE * +DEFUN(open_memstream, (bufloc, sizeloc), + char **bufloc AND size_t *sizeloc) +{ + FILE *stream; + struct memstream_info *info; + + if (bufloc == NULL || sizeloc == NULL) + { + errno = EINVAL; + return NULL; + } + + stream = fmemopen ((char *) NULL, BUFSIZ, "w+"); + if (stream == NULL) + return NULL; + + info = (struct memstream_info *) malloc (sizeof (struct memstream_info)); + if (info == NULL) + { + int save = errno; + (void) fclose (stream); + errno = save; + return NULL; + } + + stream->__room_funcs.__output = enlarge_buffer; + stream->__io_funcs.__seek = seek; + stream->__io_funcs.__close = free_info; + stream->__cookie = (PTR) info; + stream->__userbuf = 1; + + info->buffer = bufloc; + info->bufsize = sizeloc; + + *bufloc = stream->__buffer; + + return stream; +} |