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107 lines
4.3 KiB
Plaintext
107 lines
4.3 KiB
Plaintext
@findex struct bfd_iovec
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@subsubsection @code{struct bfd_iovec}
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@strong{Description}@*
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The @code{struct bfd_iovec} contains the internal file I/O class.
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Each @code{BFD} has an instance of this class and all file I/O is
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routed through it (it is assumed that the instance implements
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all methods listed below).
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@example
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struct bfd_iovec
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@{
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/* To avoid problems with macros, a "b" rather than "f"
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prefix is prepended to each method name. */
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/* Attempt to read/write NBYTES on ABFD's IOSTREAM storing/fetching
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bytes starting at PTR. Return the number of bytes actually
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transfered (a read past end-of-file returns less than NBYTES),
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or -1 (setting @code{bfd_error}) if an error occurs. */
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file_ptr (*bread) (struct bfd *abfd, void *ptr, file_ptr nbytes);
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file_ptr (*bwrite) (struct bfd *abfd, const void *ptr,
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file_ptr nbytes);
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/* Return the current IOSTREAM file offset, or -1 (setting @code{bfd_error}
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if an error occurs. */
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file_ptr (*btell) (struct bfd *abfd);
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/* For the following, on successful completion a value of 0 is returned.
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Otherwise, a value of -1 is returned (and @code{bfd_error} is set). */
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int (*bseek) (struct bfd *abfd, file_ptr offset, int whence);
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int (*bclose) (struct bfd *abfd);
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int (*bflush) (struct bfd *abfd);
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int (*bstat) (struct bfd *abfd, struct stat *sb);
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/* Mmap a part of the files. ADDR, LEN, PROT, FLAGS and OFFSET are the usual
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mmap parameter, except that LEN and OFFSET do not need to be page
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aligned. Returns (void *)-1 on failure, mmapped address on success.
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Also write in MAP_ADDR the address of the page aligned buffer and in
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MAP_LEN the size mapped (a page multiple). Use unmap with MAP_ADDR and
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MAP_LEN to unmap. */
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void *(*bmmap) (struct bfd *abfd, void *addr, bfd_size_type len,
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int prot, int flags, file_ptr offset,
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void **map_addr, bfd_size_type *map_len);
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@};
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extern const struct bfd_iovec _bfd_memory_iovec;
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@end example
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@findex bfd_get_mtime
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@subsubsection @code{bfd_get_mtime}
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@strong{Synopsis}
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@example
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long bfd_get_mtime (bfd *abfd);
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@end example
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@strong{Description}@*
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Return the file modification time (as read from the file system, or
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from the archive header for archive members).
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@findex bfd_get_size
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@subsubsection @code{bfd_get_size}
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@strong{Synopsis}
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@example
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ufile_ptr bfd_get_size (bfd *abfd);
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@end example
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@strong{Description}@*
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Return the file size (as read from file system) for the file
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associated with BFD @var{abfd}.
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The initial motivation for, and use of, this routine is not
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so we can get the exact size of the object the BFD applies to, since
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that might not be generally possible (archive members for example).
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It would be ideal if someone could eventually modify
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it so that such results were guaranteed.
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Instead, we want to ask questions like "is this NNN byte sized
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object I'm about to try read from file offset YYY reasonable?"
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As as example of where we might do this, some object formats
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use string tables for which the first @code{sizeof (long)} bytes of the
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table contain the size of the table itself, including the size bytes.
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If an application tries to read what it thinks is one of these
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string tables, without some way to validate the size, and for
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some reason the size is wrong (byte swapping error, wrong location
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for the string table, etc.), the only clue is likely to be a read
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error when it tries to read the table, or a "virtual memory
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exhausted" error when it tries to allocate 15 bazillon bytes
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of space for the 15 bazillon byte table it is about to read.
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This function at least allows us to answer the question, "is the
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size reasonable?".
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@findex bfd_get_file_size
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@subsubsection @code{bfd_get_file_size}
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@strong{Synopsis}
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@example
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ufile_ptr bfd_get_file_size (bfd *abfd);
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@end example
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@strong{Description}@*
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Return the file size (as read from file system) for the file
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associated with BFD @var{abfd}. It supports both normal files
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and archive elements.
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@findex bfd_mmap
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@subsubsection @code{bfd_mmap}
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@strong{Synopsis}
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@example
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void *bfd_mmap (bfd *abfd, void *addr, bfd_size_type len,
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int prot, int flags, file_ptr offset,
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void **map_addr, bfd_size_type *map_len);
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@end example
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@strong{Description}@*
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Return mmap()ed region of the file, if possible and implemented.
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LEN and OFFSET do not need to be page aligned. The page aligned
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address and length are written to MAP_ADDR and MAP_LEN.
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