2 * collectd - src/utils_tail.c
3 * Copyright (C) 2007-2008 C-Ware, Inc.
4 * Copyright (C) 2008 Florian Forster
6 * Permission is hereby granted, free of charge, to any person obtaining a
7 * copy of this software and associated documentation files (the "Software"),
8 * to deal in the Software without restriction, including without limitation
9 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
10 * and/or sell copies of the Software, and to permit persons to whom the
11 * Software is furnished to do so, subject to the following conditions:
13 * The above copyright notice and this permission notice shall be included in
14 * all copies or substantial portions of the Software.
16 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
17 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
18 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
19 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
20 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
21 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
22 * DEALINGS IN THE SOFTWARE.
25 * Luke Heberling <lukeh at c-ware.com>
26 * Florian Forster <octo at collectd.org>
29 * Encapsulates useful code for plugins which must watch for appends to
35 #include "utils_tail.h"
44 static int cu_tail_reopen (cu_tail_t *obj)
48 struct stat stat_buf = { 0 };
51 status = stat (obj->file, &stat_buf);
55 ERROR ("utils_tail: stat (%s) failed: %s", obj->file,
56 sstrerror (errno, errbuf, sizeof (errbuf)));
60 /* The file is already open.. */
61 if ((obj->fh != NULL) && (stat_buf.st_ino == obj->stat.st_ino))
63 /* Seek to the beginning if file was truncated */
64 if (stat_buf.st_size < obj->stat.st_size)
66 INFO ("utils_tail: File `%s' was truncated.", obj->file);
67 status = fseek (obj->fh, 0, SEEK_SET);
71 ERROR ("utils_tail: fseek (%s) failed: %s", obj->file,
72 sstrerror (errno, errbuf, sizeof (errbuf)));
78 memcpy (&obj->stat, &stat_buf, sizeof (struct stat));
82 /* Seek to the end if we re-open the same file again or the file opened
83 * is the first at all or the first after an error */
84 if ((obj->stat.st_ino == 0) || (obj->stat.st_ino == stat_buf.st_ino))
87 fh = fopen (obj->file, "r");
91 ERROR ("utils_tail: fopen (%s) failed: %s", obj->file,
92 sstrerror (errno, errbuf, sizeof (errbuf)));
98 status = fseek (fh, 0, SEEK_END);
102 ERROR ("utils_tail: fseek (%s) failed: %s", obj->file,
103 sstrerror (errno, errbuf, sizeof (errbuf)));
112 memcpy (&obj->stat, &stat_buf, sizeof (struct stat));
115 } /* int cu_tail_reopen */
117 cu_tail_t *cu_tail_create (const char *file)
121 obj = calloc (1, sizeof (*obj));
125 obj->file = strdup (file);
126 if (obj->file == NULL)
135 } /* cu_tail_t *cu_tail_create */
137 int cu_tail_destroy (cu_tail_t *obj)
145 } /* int cu_tail_destroy */
147 int cu_tail_readline (cu_tail_t *obj, char *buf, int buflen)
153 ERROR ("utils_tail: cu_tail_readline: buflen too small: %i bytes.",
160 status = cu_tail_reopen (obj);
164 assert (obj->fh != NULL);
166 /* Try to read from the filehandle. If that succeeds, everything appears to
167 * be fine and we can return. */
169 if (fgets (buf, buflen, obj->fh) != NULL)
175 /* Check if we encountered an error */
176 if (ferror (obj->fh) != 0)
178 /* Jupp, error. Force `cu_tail_reopen' to reopen the file.. */
182 /* else: eof -> check if the file was moved away and reopen the new file if
185 status = cu_tail_reopen (obj);
186 /* error -> return with error */
189 /* file end reached and file not reopened -> nothing more to read */
196 /* If we get here: file was re-opened and there may be more to read.. Let's
198 if (fgets (buf, buflen, obj->fh) != NULL)
204 if (ferror (obj->fh) != 0)
207 WARNING ("utils_tail: fgets (%s) returned an error: %s", obj->file,
208 sstrerror (errno, errbuf, sizeof (errbuf)));
214 /* EOf, well, apparently the new file is empty.. */
217 } /* int cu_tail_readline */
219 int cu_tail_read (cu_tail_t *obj, char *buf, int buflen, tailfunc_t *callback,
228 status = cu_tail_readline (obj, buf, buflen);
231 ERROR ("utils_tail: cu_tail_read: cu_tail_readline "
242 if (buf[len - 1] != '\n')
248 status = callback (data, buf, buflen);
251 ERROR ("utils_tail: cu_tail_read: callback returned "
252 "status %i.", status);
258 } /* int cu_tail_read */