external/ibm-public/postfix/dist/src/global/file_id.c

   1 /*      $NetBSD$        */
   2
   3 /*++
   4 /* NAME
   5 /*      file_id 3
   6 /* SUMMARY
   7 /*      file ID printable representation
   8 /* SYNOPSIS
   9 /*      #include <file_id.h>
  10 /*
  11 /*      const char *get_file_id(fd)
  12 /*      int     fd;
  13 /*
  14 /*      int     check_file_id(fd, id)
  15 /*      int     fd;
  16 /*      const char *id;
  17 /* DESCRIPTION
  18 /*      get_file_id() queries the operating system for the unique identifier
  19 /*      for the specified file and returns a printable representation.
  20 /*      The result is volatile.  Make a copy if it is to be used for any
  21 /*      appreciable amount of time.
  22 /*
  23 /*      check_file_id() tests if an open file matches the given
  24 /*      printable FILE ID representation.
  25 /*
  26 /*      Arguments:
  27 /* .IP fd
  28 /*      A valid file descriptor that is associated with an open file.
  29 /* .IP id
  30 /*      Printable file ID.
  31 /* DIAGNOSTICS
  32 /*      All errors are fatal.
  33 /* LICENSE
  34 /* .ad
  35 /* .fi
  36 /*      The Secure Mailer license must be distributed with this software.
  37 /* AUTHOR(S)
  38 /*      Wietse Venema
  39 /*      IBM T.J. Watson Research
  40 /*      P.O. Box 704
  41 /*      Yorktown Heights, NY 10598, USA
  42 /*--*/
  43
  44 /* System library. */
  45
  46 #include <sys_defs.h>
  47 #include <sys/stat.h>
  48 #include <string.h>
  49
  50 /* Utility library */
  51
  52 #include <msg.h>
  53 #include <vstring.h>
  54
  55 /* Global library. */
  56
  57 #include "file_id.h"
  58
  59 /* get_file_id - lookup file ID, convert to printable form */
  60
  61 const char *get_file_id(int fd)
  62 {
  63     static VSTRING *result;
  64     struct stat st;
  65
  66     if (result == 0)
  67         result = vstring_alloc(1);
  68     if (fstat(fd, &st) < 0)
  69         msg_fatal("fstat: %m");
  70     vstring_sprintf(result, "%lX", (long) st.st_ino);
  71     return (vstring_str(result));
  72 }
  73
  74 /* check_file_id - make sure file name matches ID */
  75
  76 int     check_file_id(int fd, const char *name)
  77 {
  78     return (strcmp(get_file_id(fd), name));
  79 }