src/utils_tail.[ch]: Added a generic interface for `tail'ing files.

This will be used to parse logfiles in the near future.

diff --git a/src/Makefile.am b/src/Makefile.am
index 30ea1ee38d6f9e2611eaa78134e36e85a464a126..50ad0c9974a647ccbb8de853ff074a5adc056feb 100644 (file)
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -31,6 +31,7 @@ collectd_SOURCES = collectd.c collectd.h \
                   utils_ignorelist.c utils_ignorelist.h \
                   utils_llist.c utils_llist.h \
                   utils_mount.c utils_mount.h \
+                  utils_tail.c utils_tail.h \
                   utils_threshold.c utils_threshold.h \
                   types_list.c types_list.h
 collectd_CPPFLAGS = $(LTDLINCL)

diff --git a/src/utils_tail.c b/src/utils_tail.c
new file mode 100644 (file)
index 0000000..5e5aa03
--- /dev/null
+++ b/src/utils_tail.c
@@ -0,0 +1,129 @@
+/**
+ * collectd - src/utils_tail.c
+ * Copyright (C) 2008  C-Ware, Inc.
+ *
+ * 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
+ * Free Software Foundation; only version 2 of the License is applicable.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
+ *
+ * Author:
+ *   Luke Heberling <lukeh at c-ware.com>
+ *
+ * Description:
+ *   Encapsulates useful code for plugins which must watch for appends to
+ *   the end of a file.
+ **/
+
+
+#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;
+       struct stat stat;
+};
+
+cu_tail_t *cu_tail_create (const char *file)
+{
+       cu_tail_t *obj;
+
+       obj = (cu_tail_t *) malloc (sizeof (cu_tail_t));
+       if (obj == NULL)
+               return (NULL);
+       memset (obj, '\0', sizeof (cu_tail_t));
+
+       obj->file = strdup (file);
+       if (obj->file == NULL)
+       {
+               free (obj);
+               return (NULL);
+       }
+
+       obj->fd = NULL;
+
+       return (obj);
+} /* cu_tail_t *cu_tail_create */
+
+int cu_tail_destroy (cu_tail_t *obj)
+{
+       if (obj->fd != NULL)
+               fclose (obj->fd);
+       free (obj->file);
+       free (obj);
+
+       return (0);
+} /* int cu_tail_destroy */
+
+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 cu_tail_readline */
+
+int cu_tail_read (cu_tail_t *obj, char *buf, int buflen, tailfunc *func, void *data)
+{
+       int ret;
+
+       while ((ret = cu_tail_readline (obj, buf, buflen)) == 0)
+               if (*buf == '\0' || (ret = func (data, buf, buflen)))
+                               break;
+
+       return ret;
+} /* int cu_tail_read */
+

diff --git a/src/utils_tail.h b/src/utils_tail.h
new file mode 100644 (file)
index 0000000..a456870
--- /dev/null
+++ b/src/utils_tail.h
@@ -0,0 +1,77 @@
+/**
+ * collectd - src/utils_tail.h
+ * Copyright (C) 2007  C-Ware, Inc.
+ *
+ * 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
+ * Free Software Foundation; only version 2 of the License is applicable.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
+ *
+ * Author:
+ *   Luke Heberling <lukeh at c-ware.com>
+ *
+ * DESCRIPTION
+ *   Facilitates reading information that is appended to a file, taking into
+ *   account that the file may be rotated and a new file created under the
+ *   same name.
+ **/
+
+#ifndef UTILS_TAIL_H
+#define UTILS_TAIL_H 1
+
+struct cu_tail_s;
+typedef struct cu_tail_s cu_tail_t;
+
+typedef int tailfunc(void *data, char *buf, int buflen);
+
+/*
+ * NAME
+ *   cu_tail_create
+ *
+ * DESCRIPTION
+ *   Allocates a new tail object..
+ *
+ * PARAMETERS
+ *   `file'       The name of the file to be tailed.
+ */
+cu_tail_t *cu_tail_create (const char *file);
+
+/*
+ * cu_tail_destroy
+ *
+ * Takes a tail object returned by `cu_tail_create' and destroys it, freeing
+ * all internal memory.
+ *
+ * Returns 0 when successful and non-zero otherwise.
+ */
+int cu_tail_destroy (cu_tail_t *obj);
+
+/*
+ * cu_tail_readline
+ *
+ * Reads from the file until `buflen' characters are read, a newline
+ * character is read, or an eof condition is encountered. `buf' is
+ * always null-terminated on successful return.
+ *
+ * Returns 0 when successful and non-zero otherwise.
+ */
+int cu_tail_readline (cu_tail_t *obj, char *buf, int buflen);
+
+/*
+ * cu_tail_readline
+ *
+ * Reads from the file until eof condition or an error is encountered.
+ *
+ * Returns 0 when successful and non-zero otherwise.
+ */
+int cu_tail_read (cu_tail_t *obj, char *buf, int buflen, tailfunc *func, void *data);
+
+#endif /* UTILS_TAIL_H */