| 1 | /* -*-c-*- |
| 2 | * |
| 3 | * $Id: fwatch.c,v 1.1 2001/02/03 18:43:56 mdw Exp $ |
| 4 | * |
| 5 | * Watch a file for changes |
| 6 | * |
| 7 | * (c) 2001 Straylight/Edgeware |
| 8 | */ |
| 9 | |
| 10 | /*----- Licensing notice --------------------------------------------------* |
| 11 | * |
| 12 | * This file is part of the mLib utilities library. |
| 13 | * |
| 14 | * mLib is free software; you can redistribute it and/or modify |
| 15 | * it under the terms of the GNU Library General Public License as |
| 16 | * published by the Free Software Foundation; either version 2 of the |
| 17 | * License, or (at your option) any later version. |
| 18 | * |
| 19 | * mLib is distributed in the hope that it will be useful, |
| 20 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 21 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 22 | * GNU Library General Public License for more details. |
| 23 | * |
| 24 | * You should have received a copy of the GNU Library General Public |
| 25 | * License along with mLib; if not, write to the Free |
| 26 | * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, |
| 27 | * MA 02111-1307, USA. |
| 28 | */ |
| 29 | |
| 30 | /*----- Revision history --------------------------------------------------* |
| 31 | * |
| 32 | * $Log: fwatch.c,v $ |
| 33 | * Revision 1.1 2001/02/03 18:43:56 mdw |
| 34 | * New feature: watch a file for changes. |
| 35 | * |
| 36 | */ |
| 37 | |
| 38 | /*----- Header files ------------------------------------------------------*/ |
| 39 | |
| 40 | #include <errno.h> |
| 41 | |
| 42 | #include <sys/types.h> |
| 43 | #include <sys/stat.h> |
| 44 | |
| 45 | #include "fwatch.h" |
| 46 | |
| 47 | /*----- Main code ---------------------------------------------------------*/ |
| 48 | |
| 49 | /* --- @doupdate@ --- * |
| 50 | * |
| 51 | * Arguments: @fwatch *f@ = pointer to an @fwatch@ structure |
| 52 | * @struct stat *st@ = pointer to file state |
| 53 | * @int err@ = whether there was an error |
| 54 | * |
| 55 | * Returns: Nonzero if the file has changed. |
| 56 | * |
| 57 | * Use: Updates the information in an @fwatch@ block. |
| 58 | */ |
| 59 | |
| 60 | static void copy(fwatch *f, struct stat *st) |
| 61 | { |
| 62 | f->dev = st->st_dev; f->ino = st->st_ino; |
| 63 | f->mtime = st->st_mtime; f->size = st->st_size; |
| 64 | f->mode = st->st_mode; |
| 65 | f->uid = st->st_uid; f->gid = st->st_gid; |
| 66 | } |
| 67 | |
| 68 | static int doupdate(fwatch *f, struct stat *st, int err) |
| 69 | { |
| 70 | /* --- Fiddle with the error state --- * |
| 71 | * |
| 72 | * Only the presence or absence of error is interesting to someone wanting |
| 73 | * to read the file. |
| 74 | */ |
| 75 | |
| 76 | if (err) |
| 77 | err = errno; |
| 78 | if (err || f->err) { |
| 79 | if (!err != !f->err) { |
| 80 | f->err = err; |
| 81 | if (!err) |
| 82 | copy(f, st); |
| 83 | return (1); |
| 84 | } |
| 85 | return (0); |
| 86 | } |
| 87 | |
| 88 | /* --- Check everything else --- */ |
| 89 | |
| 90 | if (st->st_dev != f->dev || st->st_ino != f->ino || |
| 91 | st->st_mtime != f->mtime || st->st_size != f->size || |
| 92 | st->st_mode != f->mode || |
| 93 | st->st_uid != f->uid || st->st_gid != f->gid) { |
| 94 | copy(f, st); |
| 95 | return (1); |
| 96 | } |
| 97 | return (0); |
| 98 | } |
| 99 | |
| 100 | /* --- @fwatch_init@, @fwatch_update@, etc --- * |
| 101 | * |
| 102 | * Arguments: @fwatch *f@ = pointer to an @fwatch@ structure |
| 103 | * @const char *name@ = name of the file to watch |
| 104 | * @int fd@ = a file descriptor to watch |
| 105 | * |
| 106 | * Returns: The @update@ functions return nonzero if the file has |
| 107 | * changed. |
| 108 | * |
| 109 | * Use: Stores information about a file which can be used to watch |
| 110 | * for changes. The structures may be freed without telling |
| 111 | * anyone. |
| 112 | */ |
| 113 | |
| 114 | void fwatch_init(fwatch *f, const char *name) |
| 115 | { |
| 116 | struct stat st; |
| 117 | memset(f, 0, sizeof(*f)); |
| 118 | doupdate(f, &st, stat(name, &st)); |
| 119 | } |
| 120 | |
| 121 | void fwatch_initfd(fwatch *f, int fd) |
| 122 | { |
| 123 | struct stat st; |
| 124 | memset(f, 0, sizeof(*f)); |
| 125 | doupdate(f, &st, fstat(fd, &st)); |
| 126 | } |
| 127 | |
| 128 | int fwatch_update(fwatch *f, const char *name) |
| 129 | { |
| 130 | struct stat st; |
| 131 | return (doupdate(f, &st, stat(name, &st))); |
| 132 | } |
| 133 | |
| 134 | int fwatch_updatefd(fwatch *f, int fd) |
| 135 | { |
| 136 | struct stat st; |
| 137 | return (doupdate(f, &st, fstat(fd, &st))); |
| 138 | } |
| 139 | |
| 140 | /*----- That's all, folks -------------------------------------------------*/ |