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      1 @findex struct bfd_iovec
      2 @subsubsection @code{struct bfd_iovec}
      3 The @code{struct bfd_iovec} contains the internal file I/O class.
      4 Each @code{BFD} has an instance of this class and all file I/O is
      5 routed through it (it is assumed that the instance implements
      6 all methods listed below).
      7 @example
      8 struct bfd_iovec
      9 @{
     10   /* To avoid problems with macros, a "b" rather than "f"
     11      prefix is prepended to each method name.  */
     12   /* Attempt to read/write NBYTES on ABFD's IOSTREAM storing/fetching
     13      bytes starting at PTR.  Return the number of bytes actually
     14      transfered (a read past end-of-file returns less than NBYTES),
     15      or -1 (setting @code{bfd_error}) if an error occurs.  */
     16   file_ptr (*bread) (struct bfd *abfd, void *ptr, file_ptr nbytes);
     17   file_ptr (*bwrite) (struct bfd *abfd, const void *ptr,
     18                       file_ptr nbytes);
     19   /* Return the current IOSTREAM file offset, or -1 (setting @code{bfd_error}
     20      if an error occurs.  */
     21   file_ptr (*btell) (struct bfd *abfd);
     22   /* For the following, on successful completion a value of 0 is returned.
     23      Otherwise, a value of -1 is returned (and @code{bfd_error} is set).  */
     24   int (*bseek) (struct bfd *abfd, file_ptr offset, int whence);
     25   int (*bclose) (struct bfd *abfd);
     26   int (*bflush) (struct bfd *abfd);
     27   int (*bstat) (struct bfd *abfd, struct stat *sb);
     28   /* Mmap a part of the files. ADDR, LEN, PROT, FLAGS and OFFSET are the usual
     29      mmap parameter, except that LEN and OFFSET do not need to be page
     30      aligned.  Returns MAP_FAILED on failure, mmapped address on success.
     31      Also write in MAP_ADDR the address of the page aligned buffer and in
     32      MAP_LEN the size mapped (a page multiple).  Use unmap with MAP_ADDR and
     33      MAP_LEN to unmap.  */
     34   void *(*bmmap) (struct bfd *abfd, void *addr, size_t len,
     35                   int prot, int flags, file_ptr offset,
     36                   void **map_addr, size_t *map_len);
     37 @};
     38 extern const struct bfd_iovec _bfd_memory_iovec;
     39 
     40 @end example
     41 
     42 @findex bfd_read
     43 @subsubsection @code{bfd_read}
     44 @deftypefn {Function} bfd_size_type bfd_read (void *, bfd_size_type, bfd *) ATTRIBUTE_WARN_UNUSED_RESULT; 
     45 Attempt to read SIZE bytes from ABFD's iostream to PTR.
     46 Return the amount read.
     47 
     48 @end deftypefn
     49 @findex bfd_write
     50 @subsubsection @code{bfd_write}
     51 @deftypefn {Function} bfd_size_type bfd_write (const void *, bfd_size_type, bfd *) ATTRIBUTE_WARN_UNUSED_RESULT; 
     52 Attempt to write SIZE bytes to ABFD's iostream from PTR.
     53 Return the amount written.
     54 
     55 @end deftypefn
     56 @findex bfd_tell
     57 @subsubsection @code{bfd_tell}
     58 @deftypefn {Function} file_ptr bfd_tell (bfd *) ATTRIBUTE_WARN_UNUSED_RESULT; 
     59 Return ABFD's iostream file position.
     60 
     61 @end deftypefn
     62 @findex bfd_flush
     63 @subsubsection @code{bfd_flush}
     64 @deftypefn {Function} int bfd_flush (bfd *); 
     65 Flush ABFD's iostream pending IO.
     66 
     67 @end deftypefn
     68 @findex bfd_stat
     69 @subsubsection @code{bfd_stat}
     70 @deftypefn {Function} int bfd_stat (bfd *, struct stat *) ATTRIBUTE_WARN_UNUSED_RESULT; 
     71 Call fstat on ABFD's iostream.  Return 0 on success, and a
     72 negative value on failure.
     73 
     74 @end deftypefn
     75 @findex bfd_seek
     76 @subsubsection @code{bfd_seek}
     77 @deftypefn {Function} int bfd_seek (bfd *, file_ptr, int) ATTRIBUTE_WARN_UNUSED_RESULT; 
     78 Call fseek on ABFD's iostream.  Return 0 on success, and a
     79 negative value on failure.
     80 
     81 @end deftypefn
     82 @findex bfd_get_mtime
     83 @subsubsection @code{bfd_get_mtime}
     84 @deftypefn {Function} long bfd_get_mtime (bfd *abfd); 
     85 Return the file modification time (as read from the file system, or
     86 from the archive header for archive members).
     87 
     88 @end deftypefn
     89 @findex bfd_get_size
     90 @subsubsection @code{bfd_get_size}
     91 @deftypefn {Function} ufile_ptr bfd_get_size (bfd *abfd); 
     92 Return the file size (as read from file system) for the file
     93 associated with BFD @var{abfd}.
     94 
     95 The initial motivation for, and use of, this routine is not
     96 so we can get the exact size of the object the BFD applies to, since
     97 that might not be generally possible (archive members for example).
     98 It would be ideal if someone could eventually modify
     99 it so that such results were guaranteed.
    100 
    101 Instead, we want to ask questions like "is this NNN byte sized
    102 object I'm about to try read from file offset YYY reasonable?"
    103 As as example of where we might do this, some object formats
    104 use string tables for which the first @code{sizeof (long)} bytes of the
    105 table contain the size of the table itself, including the size bytes.
    106 If an application tries to read what it thinks is one of these
    107 string tables, without some way to validate the size, and for
    108 some reason the size is wrong (byte swapping error, wrong location
    109 for the string table, etc.), the only clue is likely to be a read
    110 error when it tries to read the table, or a "virtual memory
    111 exhausted" error when it tries to allocate 15 bazillon bytes
    112 of space for the 15 bazillon byte table it is about to read.
    113 This function at least allows us to answer the question, "is the
    114 size reasonable?".
    115 
    116 A return value of zero indicates the file size is unknown.
    117 
    118 @end deftypefn
    119 @findex bfd_get_file_size
    120 @subsubsection @code{bfd_get_file_size}
    121 @deftypefn {Function} ufile_ptr bfd_get_file_size (bfd *abfd); 
    122 Return the file size (as read from file system) for the file
    123 associated with BFD @var{abfd}.  It supports both normal files
    124 and archive elements.
    125 
    126 @end deftypefn
    127 @findex bfd_mmap
    128 @subsubsection @code{bfd_mmap}
    129 @deftypefn {Function} void *bfd_mmap (bfd *abfd, void *addr, size_t len, int prot, int flags, file_ptr offset, void **map_addr, size_t *map_len) ATTRIBUTE_WARN_UNUSED_RESULT; 
    130 Return mmap()ed region of the file, if possible and implemented.
    131 LEN and OFFSET do not need to be page aligned.  The page aligned
    132 address and length are written to MAP_ADDR and MAP_LEN.
    133 Returns MAP_FAILED on failure.
    134 
    135 @end deftypefn
    136 @findex bfd_get_current_time
    137 @subsubsection @code{bfd_get_current_time}
    138 @deftypefn {Function} time_t bfd_get_current_time (time_t now); 
    139 Returns the current time.
    140 
    141 If the environment variable SOURCE_DATE_EPOCH is defined
    142 then this is parsed and its value is returned.  Otherwise
    143 if the paramter NOW is non-zero, then that is returned.
    144 Otherwise the result of the system call "time(NULL)" is
    145 returned.
    146 
    147 @end deftypefn
    148