diff options
Diffstat (limited to 'newlib/libc/stdio/ungetc.c')
| -rw-r--r-- | newlib/libc/stdio/ungetc.c | 145 |
1 files changed, 145 insertions, 0 deletions
diff --git a/newlib/libc/stdio/ungetc.c b/newlib/libc/stdio/ungetc.c new file mode 100644 index 00000000000..418717e689e --- /dev/null +++ b/newlib/libc/stdio/ungetc.c @@ -0,0 +1,145 @@ +/* + * Copyright (c) 1990 The Regents of the University of California. + * All rights reserved. + * + * Redistribution and use in source and binary forms are permitted + * provided that the above copyright notice and this paragraph are + * duplicated in all such forms and that any documentation, + * advertising materials, and other materials related to such + * distribution and use acknowledge that the software was developed + * by the University of California, Berkeley. The name of the + * University may not be used to endorse or promote products derived + * from this software without specific prior written permission. + * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR + * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED + * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. + */ + +#if defined(LIBC_SCCS) && !defined(lint) +static char sccsid[] = "%W% (Berkeley) %G%"; +#endif /* LIBC_SCCS and not lint */ + +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include "local.h" + +/* + * Expand the ungetc buffer `in place'. That is, adjust fp->_p when + * the buffer moves, so that it points the same distance from the end, + * and move the bytes in the buffer around as necessary so that they + * are all at the end (stack-style). + */ + +/*static*/ +int +__submore (fp) + register FILE *fp; +{ + register int i; + register unsigned char *p; + + if (fp->_ub._base == fp->_ubuf) + { + /* + * Get a new buffer (rather than expanding the old one). + */ + if ((p = (unsigned char *) _malloc_r (fp->_data, (size_t) BUFSIZ)) == NULL) + return EOF; + fp->_ub._base = p; + fp->_ub._size = BUFSIZ; + p += BUFSIZ - sizeof (fp->_ubuf); + for (i = sizeof (fp->_ubuf); --i >= 0;) + p[i] = fp->_ubuf[i]; + fp->_p = p; + return 0; + } + i = fp->_ub._size; + p = (unsigned char *) _realloc_r (fp->_data, (_PTR) (fp->_ub._base), i << 1); + if (p == NULL) + return EOF; + (void) memcpy ((void *) (p + i), (void *) p, (size_t) i); + fp->_p = p + i; + fp->_ub._base = p; + fp->_ub._size = i << 1; + return 0; +} + +int +ungetc (c, fp) + int c; + register FILE *fp; +{ + if (c == EOF) + return (EOF); + + /* Ensure stdio has been initialized. + ??? Might be able to remove this as some other stdio routine should + have already been called to get the char we are un-getting. */ + + CHECK_INIT (fp); + + /* After ungetc, we won't be at eof anymore */ + fp->_flags &= ~__SEOF; + + if ((fp->_flags & __SRD) == 0) + { + /* + * Not already reading: no good unless reading-and-writing. + * Otherwise, flush any current write stuff. + */ + if ((fp->_flags & __SRW) == 0) + return EOF; + if (fp->_flags & __SWR) + { + if (fflush (fp)) + return EOF; + fp->_flags &= ~__SWR; + fp->_w = 0; + fp->_lbfsize = 0; + } + fp->_flags |= __SRD; + } + c = (unsigned char) c; + + /* + * If we are in the middle of ungetc'ing, just continue. + * This may require expanding the current ungetc buffer. + */ + + if (HASUB (fp)) + { + if (fp->_r >= fp->_ub._size && __submore (fp)) + return EOF; + *--fp->_p = c; + fp->_r++; + return c; + } + + /* + * If we can handle this by simply backing up, do so, + * but never replace the original character. + * (This makes sscanf() work when scanning `const' data.) + */ + + if (fp->_bf._base != NULL && fp->_p > fp->_bf._base && fp->_p[-1] == c) + { + fp->_p--; + fp->_r++; + return c; + } + + /* + * Create an ungetc buffer. + * Initially, we will use the `reserve' buffer. + */ + + fp->_ur = fp->_r; + fp->_up = fp->_p; + fp->_ub._base = fp->_ubuf; + fp->_ub._size = sizeof (fp->_ubuf); + fp->_ubuf[sizeof (fp->_ubuf) - 1] = c; + fp->_p = &fp->_ubuf[sizeof (fp->_ubuf) - 1]; + fp->_r = 1; + return c; +} |