32e1147e |
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 -------------------------------------------------*/ |