DragonFly On-Line Manual Pages

sf_file(3)            DragonFly Library Functions Manual            sf_file(3)

NAME
     initfdpos, initFILEpos, adjfdpos, adjFILEpos - file positions indicator
     handling

SYNOPSIS
     #include <stdio.h>
     #include <strfunc.h>

     int
     initfdpos(const char *fname, int stream, const char *ext);

     int
     initFILEpos(const char *fname, FILE *stream, const char *ext);

     int
     adjfdpos(int stream, int posfd, int doSync);

     int
     adjFILEpos(FILE *stream, int posfd, int doSync);

DESCRIPTION
     Those functions are used to maintain a file positions indicator between
     the program sessions. This is often needed when a process is being parsed
     a log file and tries to save current position within this log to start
     from this point later.

     int initfdpos(const char *fname, int stream, const char *ext) creates a
     position indicator file "<fname>.<ext>", and returns its file descriptor.
     If the position file is already exists, then it advances stream's
     position according to the information derived from that file.  initfdpos
     also checks the file size and inode changes in order to be robust in
     situations when file shrinked or replaced.

     int initFILEpos() is almost the same except that it takes a FILE *
     argument instead of plain file descriptor.

     Both functions returns position file descriptor, or -1 in case of
     failure.

     int adjfdpos(int stream, int posfd, int doSync) and adFILEdpos() writes
     the current position within the file referenced by stream into the posfd.
     If doSync is not zero, it also does fsync(2).

     Return values: 0 (Success) or -1 in case of any errors.

EXAMPLE
     void main() {
             int posfd;
             FILE *logfile;
             char buf[1042];

             logfile = fopen("file.log", "r");
             if(!logfile)
                     exit(EX_NOINPUT);

             while(fgets(buf, sizeof(buf), logfile)) {
                     /* Do something ... */

                     adjFILEpos(logfile, posfd, 0);
             };

             /* Force data to be flushed on disk. */
             adjFILEpos(logfile, posfd, 1);
             fclose(logfile);
             close(posfd);
     };

SEE ALSO
     strfunc(3).

AUTHORS
     Lev Walkin <vlm@lionet.info>

DragonFly 6.5-DEVELOPMENT      December 4, 2000      DragonFly 6.5-DEVELOPMENT