/**
* collectd - src/utils_tail.c
- * Copyright (C) 2008 C-Ware, Inc.
+ * Copyright (C) 2007-2008 C-Ware, Inc.
+ * Copyright (C) 2008 Florian Forster
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the
*
* Author:
* Luke Heberling <lukeh at c-ware.com>
+ * Florian Forster <octo at verplant.org>
*
* Description:
* Encapsulates useful code for plugins which must watch for appends to
* the end of a file.
**/
-
+#include "collectd.h"
+#include "common.h"
#include "utils_tail.h"
-#include <stdio.h>
-#include <sys/stat.h>
-#include <string.h>
-#include <malloc.h>
struct cu_tail_s
{
char *file;
- FILE *fd;
+ FILE *fh;
struct stat stat;
};
+static int cu_tail_reopen (cu_tail_t *obj)
+{
+ int seek_end = 0;
+ FILE *fh;
+ struct stat stat_buf;
+ int status;
+
+ memset (&stat_buf, 0, sizeof (stat_buf));
+ status = stat (obj->file, &stat_buf);
+ if (status != 0)
+ {
+ char errbuf[1024];
+ ERROR ("utils_tail: stat (%s) failed: %s", obj->file,
+ sstrerror (errno, errbuf, sizeof (errbuf)));
+ return (-1);
+ }
+
+ /* The file is already open.. */
+ if ((obj->fh != NULL) && (stat_buf.st_ino == obj->stat.st_ino))
+ {
+ /* Seek to the beginning if file was truncated */
+ if (stat_buf.st_size < obj->stat.st_size)
+ {
+ INFO ("utils_tail: File `%s' was truncated.", obj->file);
+ status = fseek (obj->fh, 0, SEEK_SET);
+ if (status != 0)
+ {
+ char errbuf[1024];
+ ERROR ("utils_tail: fseek (%s) failed: %s", obj->file,
+ sstrerror (errno, errbuf, sizeof (errbuf)));
+ fclose (obj->fh);
+ obj->fh = NULL;
+ return (-1);
+ }
+ }
+ memcpy (&obj->stat, &stat_buf, sizeof (struct stat));
+ return (1);
+ }
+
+ /* Seek to the end if we re-open the same file again or the file opened
+ * is the first at all or the first after an error */
+ if ((obj->stat.st_ino == 0) || (obj->stat.st_ino == stat_buf.st_ino))
+ seek_end = 1;
+
+ fh = fopen (obj->file, "r");
+ if (fh == NULL)
+ {
+ char errbuf[1024];
+ ERROR ("utils_tail: fopen (%s) failed: %s", obj->file,
+ sstrerror (errno, errbuf, sizeof (errbuf)));
+ return (-1);
+ }
+
+ if (seek_end != 0)
+ {
+ status = fseek (fh, 0, SEEK_END);
+ if (status != 0)
+ {
+ char errbuf[1024];
+ ERROR ("utils_tail: fseek (%s) failed: %s", obj->file,
+ sstrerror (errno, errbuf, sizeof (errbuf)));
+ fclose (fh);
+ return (-1);
+ }
+ }
+
+ if (obj->fh != NULL)
+ fclose (obj->fh);
+ obj->fh = fh;
+ memcpy (&obj->stat, &stat_buf, sizeof (struct stat));
+
+ return (0);
+} /* int cu_tail_reopen */
+
cu_tail_t *cu_tail_create (const char *file)
{
cu_tail_t *obj;
return (NULL);
}
- obj->fd = NULL;
+ obj->fh = NULL;
return (obj);
} /* cu_tail_t *cu_tail_create */
int cu_tail_destroy (cu_tail_t *obj)
{
- if (obj->fd != NULL)
- fclose (obj->fd);
+ if (obj->fh != NULL)
+ fclose (obj->fh);
free (obj->file);
free (obj);
int cu_tail_readline (cu_tail_t *obj, char *buf, int buflen)
{
- struct stat stat_now;
- FILE *new_fd;
- int len;
-
- if( buflen < 1 )
- return -1;
-
- *buf = '\0';
-
- if (stat (obj->file, &stat_now) != 0)
- return 0;
-
- if (stat_now.st_dev != obj->stat.st_dev ||
- stat_now.st_ino != obj->stat.st_ino)
- {
- new_fd = fopen (obj->file, "r");
- if (new_fd == NULL)
- return -1;
-
- if (obj->stat.st_ino == 0)
- fseek (new_fd, 0, SEEK_END);
- if (obj->fd != NULL)
- fclose (obj->fd);
- obj->fd = new_fd;
-
- }
- else if (stat_now.st_size < obj->stat.st_size)
- {
- rewind (obj->fd);
- }
-
- memcpy (&obj->stat, &stat_now, sizeof (struct stat));
-
- if (fgets (buf, buflen, obj->fd) == NULL && feof (obj->fd) == 0)
- return -1;
-
- len = strlen (buf);
- if (len > 0 && *(buf + len - 1) != '\n' && feof (obj->fd))
- {
- fseek (obj->fd, -len, SEEK_CUR);
- *buf = '\0';
- }
-
- return 0;
+ int status;
+
+ if (buflen < 1)
+ {
+ ERROR ("utils_tail: cu_tail_readline: buflen too small: %i bytes.",
+ buflen);
+ return (-1);
+ }
+
+ if (obj->fh == NULL)
+ {
+ status = cu_tail_reopen (obj);
+ if (status < 0)
+ return (status);
+ }
+ assert (obj->fh != NULL);
+
+ /* Try to read from the filehandle. If that succeeds, everything appears to
+ * be fine and we can return. */
+ clearerr (obj->fh);
+ if (fgets (buf, buflen, obj->fh) != NULL)
+ {
+ buf[buflen - 1] = 0;
+ return (0);
+ }
+
+ /* Check if we encountered an error */
+ if (ferror (obj->fh) != 0)
+ {
+ /* Jupp, error. Force `cu_tail_reopen' to reopen the file.. */
+ fclose (obj->fh);
+ obj->fh = NULL;
+ }
+ /* else: eof -> check if the file was moved away and reopen the new file if
+ * so.. */
+
+ status = cu_tail_reopen (obj);
+ /* error -> return with error */
+ if (status < 0)
+ return (status);
+ /* file end reached and file not reopened -> nothing more to read */
+ else if (status > 0)
+ {
+ buf[0] = 0;
+ return (0);
+ }
+
+ /* If we get here: file was re-opened and there may be more to read.. Let's
+ * try again. */
+ if (fgets (buf, buflen, obj->fh) != NULL)
+ {
+ buf[buflen - 1] = 0;
+ return (0);
+ }
+
+ if (ferror (obj->fh) != 0)
+ {
+ char errbuf[1024];
+ WARNING ("utils_tail: fgets (%s) returned an error: %s", obj->file,
+ sstrerror (errno, errbuf, sizeof (errbuf)));
+ fclose (obj->fh);
+ obj->fh = NULL;
+ return (-1);
+ }
+
+ /* EOf, well, apparently the new file is empty.. */
+ buf[0] = 0;
+ return (0);
} /* int cu_tail_readline */
-int cu_tail_read (cu_tail_t *obj, char *buf, int buflen, tailfunc *func, void *data)
+int cu_tail_read (cu_tail_t *obj, char *buf, int buflen, tailfunc_t *callback,
+ void *data)
{
- int ret;
+ int status;
- while ((ret = cu_tail_readline (obj, buf, buflen)) == 0)
- if (*buf == '\0' || (ret = func (data, buf, buflen)))
+ while (42)
+ {
+ size_t len;
+
+ status = cu_tail_readline (obj, buf, buflen);
+ if (status != 0)
+ {
+ ERROR ("utils_tail: cu_tail_read: cu_tail_readline "
+ "failed.");
+ break;
+ }
+
+ /* check for EOF */
+ if (buf[0] == 0)
+ break;
+
+ len = strlen (buf);
+ while (len > 0) {
+ if (buf[len - 1] != '\n')
break;
+ buf[len - 1] = '\0';
+ len--;
+ }
+
+ status = callback (data, buf, buflen);
+ if (status != 0)
+ {
+ ERROR ("utils_tail: cu_tail_read: callback returned "
+ "status %i.", status);
+ break;
+ }
+ }
- return ret;
+ return status;
} /* int cu_tail_read */
-
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