external/ibm-public/postfix/dist/src/util/load_file.c

   1 /*      $NetBSD$        */
   2
   3 /*++
   4 /* NAME
   5 /*      load_file 3
   6 /* SUMMARY
   7 /*      load file with some prejudice
   8 /* SYNOPSIS
   9 /*      #include <load_file.h>
  10 /*
  11 /*      void    load_file(path, action, context)
  12 /*      const char *path;
  13 /*      void    (*action)(VSTREAM, void *);
  14 /*      void    *context;
  15 /* DESCRIPTION
  16 /*      This routine reads a file and reads it again when the
  17 /*      file changed recently.
  18 /*
  19 /*      Arguments:
  20 /* .IP path
  21 /*      The file to be opened, read-only.
  22 /* .IP action
  23 /*      The function that presumably reads the file.
  24 /* .IP context
  25 /*      Application-specific context for the action routine.
  26 /* DIAGNOSTICS
  27 /*      Fatal errors: out of memory, cannot open file.
  28 /* LICENSE
  29 /* .ad
  30 /* .fi
  31 /*      The Secure Mailer license must be distributed with this software.
  32 /* AUTHOR(S)
  33 /*      Wietse Venema
  34 /*      IBM T.J. Watson Research
  35 /*      P.O. Box 704
  36 /*      Yorktown Heights, NY 10598, USA
  37 /*--*/
  38
  39 /* System library. */
  40
  41 #include <sys_defs.h>
  42 #include <sys/stat.h>
  43 #include <time.h>
  44
  45 /* Utility library. */
  46
  47 #include <msg.h>
  48 #include <vstream.h>
  49 #include <iostuff.h>
  50 #include <load_file.h>
  51
  52 /* load_file - load file with some prejudice */
  53
  54 void    load_file(const char *path, LOAD_FILE_FN action, void *context)
  55 {
  56     VSTREAM *fp;
  57     struct stat st;
  58     time_t  before;
  59     time_t  after;
  60
  61     /*
  62      * Read the file again if it is hot. This may result in reading a partial
  63      * parameter name or missing end marker when a file changes in the middle
  64      * of a read.
  65      */
  66     for (before = time((time_t *) 0); /* see below */ ; before = after) {
  67         if ((fp = vstream_fopen(path, O_RDONLY, 0)) == 0)
  68             msg_fatal("open %s: %m", path);
  69         action(fp, context);
  70         if (fstat(vstream_fileno(fp), &st) < 0)
  71             msg_fatal("fstat %s: %m", path);
  72         if (vstream_ferror(fp) || vstream_fclose(fp))
  73             msg_fatal("read %s: %m", path);
  74         after = time((time_t *) 0);
  75         if (st.st_mtime < before - 1 || st.st_mtime > after)
  76             break;
  77         if (msg_verbose)
  78             msg_info("pausing to let %s cool down", path);
  79         doze(300000);
  80     }
  81 }