X-Git-Url: https://git.octo.it/?p=collectd.git;a=blobdiff_plain;f=src%2Futils_tail.c;h=9d05fe11b5f9228e9862c863ff3f0bc8170acf52;hp=b73c1f99058bf5bd3544176d8bfecfd187b2f780;hb=633c3966f770e4d46651a2fe219a18d8a9907a9f;hpb=8004a97d0179978056a164dfac4355d0836227d0 diff --git a/src/utils_tail.c b/src/utils_tail.c index b73c1f99..9d05fe11 100644 --- a/src/utils_tail.c +++ b/src/utils_tail.c @@ -1,6 +1,7 @@ /** * collectd - src/utils_tail.c * 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 @@ -17,6 +18,7 @@ * * Author: * Luke Heberling + * Florian Forster * * Description: * Encapsulates useful code for plugins which must watch for appends to @@ -30,10 +32,84 @@ 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; @@ -50,15 +126,15 @@ cu_tail_t *cu_tail_create (const char *file) 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); @@ -67,74 +143,74 @@ int cu_tail_destroy (cu_tail_t *obj) int cu_tail_readline (cu_tail_t *obj, char *buf, int buflen) { - struct stat stat_now; - int status; - - if (buflen < 1) - return (-1); - - if (stat (obj->file, &stat_now) != 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 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) - { - 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; - - } - 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); - } - - status = 0; - if (fgets (buf, buflen, obj->fd) == NULL) - { - if (feof (obj->fd) == 0) - buf[0] = '\0'; - else /* an error occurred */ - status = -1; - } - - if (status == 0) - memcpy (&obj->stat, &stat_now, sizeof (struct stat)); - - return (status); + 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_t *callback, @@ -142,15 +218,37 @@ int cu_tail_read (cu_tail_t *obj, char *buf, int buflen, tailfunc_t *callback, { int status; - while ((status = cu_tail_readline (obj, buf, buflen)) == 0) + 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') + 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 status;