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107 lines
4.1 KiB
Plaintext
107 lines
4.1 KiB
Plaintext
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@section Archives
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@strong{Description}@*
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An archive (or library) is just another BFD. It has a symbol
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table, although there's not much a user program will do with it.
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The big difference between an archive BFD and an ordinary BFD
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is that the archive doesn't have sections. Instead it has a
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chain of BFDs that are considered its contents. These BFDs can
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be manipulated like any other. The BFDs contained in an
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archive opened for reading will all be opened for reading. You
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may put either input or output BFDs into an archive opened for
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output; they will be handled correctly when the archive is closed.
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Use @code{bfd_openr_next_archived_file} to step through
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the contents of an archive opened for input. You don't
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have to read the entire archive if you don't want
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to! Read it until you find what you want.
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A BFD returned by @code{bfd_openr_next_archived_file} can be
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closed manually with @code{bfd_close}. If you do not close it,
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then a second iteration through the members of an archive may
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return the same BFD. If you close the archive BFD, then all
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the member BFDs will automatically be closed as well.
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Archive contents of output BFDs are chained through the
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@code{archive_next} pointer in a BFD. The first one is findable
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through the @code{archive_head} slot of the archive. Set it with
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@code{bfd_set_archive_head} (q.v.). A given BFD may be in only
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one open output archive at a time.
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As expected, the BFD archive code is more general than the
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archive code of any given environment. BFD archives may
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contain files of different formats (e.g., a.out and coff) and
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even different architectures. You may even place archives
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recursively into archives!
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This can cause unexpected confusion, since some archive
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formats are more expressive than others. For instance, Intel
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COFF archives can preserve long filenames; SunOS a.out archives
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cannot. If you move a file from the first to the second
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format and back again, the filename may be truncated.
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Likewise, different a.out environments have different
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conventions as to how they truncate filenames, whether they
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preserve directory names in filenames, etc. When
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interoperating with native tools, be sure your files are
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homogeneous.
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Beware: most of these formats do not react well to the
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presence of spaces in filenames. We do the best we can, but
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can't always handle this case due to restrictions in the format of
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archives. Many Unix utilities are braindead in regards to
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spaces and such in filenames anyway, so this shouldn't be much
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of a restriction.
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Archives are supported in BFD in @code{archive.c}.
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@subsection Archive functions
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@findex bfd_get_next_mapent
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@subsubsection @code{bfd_get_next_mapent}
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@strong{Synopsis}
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@example
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symindex bfd_get_next_mapent
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(bfd *abfd, symindex previous, carsym **sym);
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@end example
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@strong{Description}@*
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Step through archive @var{abfd}'s symbol table (if it
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has one). Successively update @var{sym} with the next symbol's
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information, returning that symbol's (internal) index into the
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symbol table.
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Supply @code{BFD_NO_MORE_SYMBOLS} as the @var{previous} entry to get
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the first one; returns @code{BFD_NO_MORE_SYMBOLS} when you've already
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got the last one.
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A @code{carsym} is a canonical archive symbol. The only
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user-visible element is its name, a null-terminated string.
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@findex bfd_set_archive_head
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@subsubsection @code{bfd_set_archive_head}
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@strong{Synopsis}
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@example
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bfd_boolean bfd_set_archive_head (bfd *output, bfd *new_head);
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@end example
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@strong{Description}@*
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Set the head of the chain of
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BFDs contained in the archive @var{output} to @var{new_head}.
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@findex bfd_openr_next_archived_file
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@subsubsection @code{bfd_openr_next_archived_file}
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@strong{Synopsis}
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@example
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bfd *bfd_openr_next_archived_file (bfd *archive, bfd *previous);
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@end example
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@strong{Description}@*
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Provided a BFD, @var{archive}, containing an archive and NULL, open
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an input BFD on the first contained element and returns that.
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Subsequent calls should pass the archive and the previous return
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value to return a created BFD to the next contained element. NULL
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is returned when there are no more.
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Note - if you want to process the bfd returned by this call be
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sure to call bfd_check_format() on it first.
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