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
36 #include "utils_tail.h"
44 static int cu_tail_reopen(cu_tail_t *obj) {
47 struct stat stat_buf = {0};
50 status = stat(obj->file, &stat_buf);
52 ERROR("utils_tail: stat (%s) failed: %s", obj->file, STRERRNO);
56 /* The file is already open.. */
57 if ((obj->fh != NULL) && (stat_buf.st_ino == obj->stat.st_ino)) {
58 /* Seek to the beginning if file was truncated */
59 if (stat_buf.st_size < obj->stat.st_size) {
60 INFO("utils_tail: File `%s' was truncated.", obj->file);
61 status = fseek(obj->fh, 0, SEEK_SET);
63 ERROR("utils_tail: fseek (%s) failed: %s", obj->file, STRERRNO);
69 memcpy(&obj->stat, &stat_buf, sizeof(struct stat));
73 /* Seek to the end if we re-open the same file again or the file opened
74 * is the first at all or the first after an error */
75 if ((obj->stat.st_ino == 0) || (obj->stat.st_ino == stat_buf.st_ino))
78 fh = fopen(obj->file, "r");
80 ERROR("utils_tail: fopen (%s) failed: %s", obj->file, STRERRNO);
85 status = fseek(fh, 0, SEEK_END);
87 ERROR("utils_tail: fseek (%s) failed: %s", obj->file, STRERRNO);
96 memcpy(&obj->stat, &stat_buf, sizeof(struct stat));
99 } /* int cu_tail_reopen */
101 cu_tail_t *cu_tail_create(const char *file) {
104 obj = calloc(1, sizeof(*obj));
108 obj->file = strdup(file);
109 if (obj->file == NULL) {
117 } /* cu_tail_t *cu_tail_create */
119 int cu_tail_destroy(cu_tail_t *obj) {
126 } /* int cu_tail_destroy */
128 int cu_tail_readline(cu_tail_t *obj, char *buf, int buflen) {
132 ERROR("utils_tail: cu_tail_readline: buflen too small: %i bytes.", buflen);
136 if (obj->fh == NULL) {
137 status = cu_tail_reopen(obj);
141 assert(obj->fh != NULL);
143 /* Try to read from the filehandle. If that succeeds, everything appears to
144 * be fine and we can return. */
146 if (fgets(buf, buflen, obj->fh) != NULL) {
151 /* Check if we encountered an error */
152 if (ferror(obj->fh) != 0) {
153 /* Jupp, error. Force `cu_tail_reopen' to reopen the file.. */
157 /* else: eof -> check if the file was moved away and reopen the new file if
160 status = cu_tail_reopen(obj);
161 /* error -> return with error */
164 /* file end reached and file not reopened -> nothing more to read */
165 else if (status > 0) {
170 /* If we get here: file was re-opened and there may be more to read.. Let's
172 if (fgets(buf, buflen, obj->fh) != NULL) {
177 if (ferror(obj->fh) != 0) {
178 WARNING("utils_tail: fgets (%s) returned an error: %s", obj->file,
185 /* EOf, well, apparently the new file is empty.. */
188 } /* int cu_tail_readline */
190 int cu_tail_read(cu_tail_t *obj, char *buf, int buflen, tailfunc_t *callback,
197 status = cu_tail_readline(obj, buf, buflen);
199 ERROR("utils_tail: cu_tail_read: cu_tail_readline "
210 if (buf[len - 1] != '\n')
216 status = callback(data, buf, buflen);
218 ERROR("utils_tail: cu_tail_read: callback returned "
226 } /* int cu_tail_read */