diff options
Diffstat (limited to 'sendmail/libsm/ungetc.c')
| -rw-r--r-- | sendmail/libsm/ungetc.c | 181 |
1 files changed, 181 insertions, 0 deletions
diff --git a/sendmail/libsm/ungetc.c b/sendmail/libsm/ungetc.c new file mode 100644 index 0000000..2f90e14 --- /dev/null +++ b/sendmail/libsm/ungetc.c @@ -0,0 +1,181 @@ +/* + * Copyright (c) 2000-2001, 2004 Sendmail, Inc. and its suppliers. + * All rights reserved. + * Copyright (c) 1990, 1993 + * The Regents of the University of California. All rights reserved. + * + * This code is derived from software contributed to Berkeley by + * Chris Torek. + * + * By using this file, you agree to the terms and conditions set + * forth in the LICENSE file which can be found at the top level of + * the sendmail distribution. + */ + +#include <sm/gen.h> +SM_IDSTR(id, "@(#)$Id: ungetc.c,v 1.30 2005/06/14 23:07:20 ca Exp $") + +#include <stdlib.h> +#include <string.h> +#include <signal.h> +#include <sm/time.h> +#include <errno.h> +#include <sm/io.h> +#include <sm/heap.h> +#include <sm/assert.h> +#include <sm/conf.h> +#include "local.h" + +static void sm_submore_x __P((SM_FILE_T *)); + +/* +** SM_SUBMORE_X -- expand ungetc buffer +** +** Expand the ungetc buffer `in place'. That is, adjust fp->f_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). +** +** Parameters: +** fp -- the file pointer +** +** Results: +** none. +** +** Exceptions: +** F:sm_heap -- out of memory +*/ + +static void +sm_submore_x(fp) + SM_FILE_T *fp; +{ + register int i; + register unsigned char *p; + + if (fp->f_ub.smb_base == fp->f_ubuf) + { + /* Get a buffer; f_ubuf is fixed size. */ + p = sm_malloc_x((size_t) SM_IO_BUFSIZ); + fp->f_ub.smb_base = p; + fp->f_ub.smb_size = SM_IO_BUFSIZ; + p += SM_IO_BUFSIZ - sizeof(fp->f_ubuf); + for (i = sizeof(fp->f_ubuf); --i >= 0;) + p[i] = fp->f_ubuf[i]; + fp->f_p = p; + return; + } + i = fp->f_ub.smb_size; + p = sm_realloc_x(fp->f_ub.smb_base, i << 1); + + /* no overlap (hence can use memcpy) because we doubled the size */ + (void) memcpy((void *) (p + i), (void *) p, (size_t) i); + fp->f_p = p + i; + fp->f_ub.smb_base = p; + fp->f_ub.smb_size = i << 1; +} + +/* +** SM_IO_UNGETC -- place a character back into the buffer just read +** +** Parameters: +** fp -- the file pointer affected +** timeout -- time to complete ungetc +** c -- the character to place back +** +** Results: +** On success, returns value of character placed back, 0-255. +** Returns SM_IO_EOF if c == SM_IO_EOF or if last operation +** was a write and flush failed. +** +** Exceptions: +** F:sm_heap -- out of memory +*/ + +int +sm_io_ungetc(fp, timeout, c) + register SM_FILE_T *fp; + int timeout; + int c; +{ + SM_REQUIRE_ISA(fp, SmFileMagic); + if (c == SM_IO_EOF) + return SM_IO_EOF; + if (timeout == SM_TIME_IMMEDIATE) + { + /* + ** Ungetting the buffer will take time and we are wanted to + ** return immediately. So... + */ + + errno = EAGAIN; + return SM_IO_EOF; + } + + if (!Sm_IO_DidInit) + sm_init(); + if ((fp->f_flags & SMRD) == 0) + { + /* + ** Not already reading: no good unless reading-and-writing. + ** Otherwise, flush any current write stuff. + */ + + if ((fp->f_flags & SMRW) == 0) + return SM_IO_EOF; + if (fp->f_flags & SMWR) + { + if (sm_flush(fp, &timeout)) + return SM_IO_EOF; + fp->f_flags &= ~SMWR; + fp->f_w = 0; + fp->f_lbfsize = 0; + } + fp->f_flags |= SMRD; + } + 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->f_r >= fp->f_ub.smb_size) + sm_submore_x(fp); + *--fp->f_p = c; + fp->f_r++; + return c; + } + fp->f_flags &= ~SMFEOF; + + /* + ** 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->f_bf.smb_base != NULL && fp->f_p > fp->f_bf.smb_base && + fp->f_p[-1] == c) + { + fp->f_p--; + fp->f_r++; + return c; + } + + /* + ** Create an ungetc buffer. + ** Initially, we will use the `reserve' buffer. + */ + + fp->f_ur = fp->f_r; + fp->f_up = fp->f_p; + fp->f_ub.smb_base = fp->f_ubuf; + fp->f_ub.smb_size = sizeof(fp->f_ubuf); + fp->f_ubuf[sizeof(fp->f_ubuf) - 1] = c; + fp->f_p = &fp->f_ubuf[sizeof(fp->f_ubuf) - 1]; + fp->f_r = 1; + + return c; +} |
