src/utils_tail.[ch]: Streamlined error handling.

Also the coding style has been adapted to match the one of the rest of the
daemon better.

diff --git a/src/utils_tail.c b/src/utils_tail.c
index 5e5aa03d6acb85df75f8ca5e2c5fc84ac8e6a46d..2ac478f0e7c14c81897db0a0f9c18658ae26b5b1 100644 (file)
--- a/src/utils_tail.c
+++ b/src/utils_tail.c
@@ -1,6 +1,6 @@
 /**
  * collectd - src/utils_tail.c
- * Copyright (C) 2008  C-Ware, Inc.
+ * Copyright (C) 2007-2008  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
@@ -23,12 +23,9 @@
  *   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
 {
@@ -71,26 +68,45 @@ int cu_tail_destroy (cu_tail_t *obj)
 int cu_tail_readline (cu_tail_t *obj, char *buf, int buflen)
 {
        struct stat stat_now;
-       FILE *new_fd;
-       int len;
+       int status;
 
-       if( buflen < 1 )
-               return -1;
+       if (buflen < 1)
+               return (-1);
        
-       *buf = '\0';
-
        if (stat (obj->file, &stat_now) != 0)
-               return 0;
+       {
+               char errbuf[1024];
+               ERROR ("cu_tail_readline: stat (%s) failed: %s",
+                               obj->file,
+                               sstrerror (errno, errbuf, sizeof (errbuf)));
+               return (-1);
+       }
 
-       if (stat_now.st_dev != obj->stat.st_dev ||
-               stat_now.st_ino != obj->stat.st_ino)
+       if ((stat_now.st_dev != obj->stat.st_dev) ||
+               (stat_now.st_ino != obj->stat.st_ino))
        {
+               /*
+                * If the file was replaced open the new file and close the
+                * old filehandle
+                */
+               FILE *new_fd;
+
                new_fd = fopen (obj->file, "r");
                if (new_fd == NULL)
-                       return -1;
+               {
+                       char errbuf[1024];
+                       ERROR ("cu_tail_readline: open (%s) failed: %s",
+                                       obj->file,
+                                       sstrerror (errno, errbuf,
+                                               sizeof (errbuf)));
+                       return (-1);
+               }
                
+               /* If there was no previous file, seek to the end. We don't
+                * want to read in the entire file, usually. */
                if (obj->stat.st_ino == 0)
                        fseek (new_fd, 0, SEEK_END);
+
                if (obj->fd != NULL)
                        fclose (obj->fd);
                obj->fd = new_fd;
@@ -98,32 +114,44 @@ int cu_tail_readline (cu_tail_t *obj, char *buf, int buflen)
        }
        else if (stat_now.st_size < obj->stat.st_size)
        {
+               /*
+                * Else, if the file was not replaces, but the file was
+                * truncated, seek to the beginning of the file.
+                */
+               assert (obj->fd != NULL);
                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))
+       status = 0;
+       if (fgets (buf, buflen, obj->fd) == NULL)
        {
-               fseek (obj->fd, -len, SEEK_CUR);
-               *buf = '\0';
+               if (feof (obj->fd) == 0)
+                       buf[0] = '\0';
+               else /* an error occurred */
+                       status = -1;
        }
 
-       return 0;
+       if (status == 0)
+               memcpy (&obj->stat, &stat_now, sizeof (struct stat));   
+       
+       return (status);
 } /* 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 *callback,
+               void *data)
 {
-       int ret;
+       int status;
+
+       while ((status = cu_tail_readline (obj, buf, buflen)) == 0)
+       {
+               /* check for EOF */
+               if (buf[0] == '\0')
+                       break;
 
-       while ((ret = cu_tail_readline (obj, buf, buflen)) == 0)
-               if (*buf == '\0' || (ret = func (data, buf, buflen)))
-                               break;
+               status = callback (data, buf, buflen);
+               if (status != 0)
+                       break;
+       }
 
-       return ret;
+       return status;
 } /* int cu_tail_read */
-

diff --git a/src/utils_tail.h b/src/utils_tail.h
index a456870c1f962122ef5a74d52fd6618acb60dcf6..9535dae45dbbb082e5be5e05a7b147c457d4a7fb 100644 (file)
--- a/src/utils_tail.h
+++ b/src/utils_tail.h
@@ -1,6 +1,6 @@
 /**
  * collectd - src/utils_tail.h
- * Copyright (C) 2007  C-Ware, Inc.
+ * Copyright (C) 2007-2008  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
@@ -59,7 +59,12 @@ int cu_tail_destroy (cu_tail_t *obj);
  *
  * 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.
+ * always null-terminated on successful return and isn't touched when non-zero
+ * is returned.
+ *
+ * You can check if the EOF condition is reached by looking at the buffer: If
+ * the length of the string stored in the buffer is zero, EOF occurred.
+ * Otherwise at least the newline character will be in the buffer.
  *
  * Returns 0 when successful and non-zero otherwise.
  */
@@ -72,6 +77,7 @@ int cu_tail_readline (cu_tail_t *obj, char *buf, int buflen);
  *
  * Returns 0 when successful and non-zero otherwise.
  */
-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 *callback,
+               void *data);
 
 #endif /* UTILS_TAIL_H */