407 lines
16 KiB
Plaintext
407 lines
16 KiB
Plaintext
=pod
|
|
|
|
=head1 NAME
|
|
|
|
llvm-ar - LLVM archiver
|
|
|
|
=head1 SYNOPSIS
|
|
|
|
B<llvm-ar> [-]{dmpqrtx}[Rabfikouz] [relpos] [count] <archive> [files...]
|
|
|
|
|
|
=head1 DESCRIPTION
|
|
|
|
The B<llvm-ar> command is similar to the common Unix utility, C<ar>. It
|
|
archives several files together into a single file. The intent for this is
|
|
to produce archive libraries by LLVM bytecode that can be linked into an
|
|
LLVM program. However, the archive can contain any kind of file. By default,
|
|
B<llvm-ar> generates a symbol table that makes linking faster because
|
|
only the symbol table needs to be consulted, not each individual file member
|
|
of the archive.
|
|
|
|
The B<llvm-ar> command can be used to I<read> both SVR4 and BSD style archive
|
|
files. However, it cannot be used to write them. While the B<llvm-ar> command
|
|
produces files that are I<almost> identical to the format used by other C<ar>
|
|
implementations, it has two significant departures in order to make the
|
|
archive appropriate for LLVM. The first departure is that B<llvm-ar> only
|
|
uses BSD4.4 style long path names (stored immediately after the header) and
|
|
never contains a string table for long names. The second departure is that the
|
|
symbol table is formated for efficient construction of an in-memory data
|
|
structure that permits rapid (red-black tree) lookups. Consequently, archives
|
|
produced with B<llvm-ar> usually won't be readable or editable with any
|
|
C<ar> implementation or useful for linking. Using the C<f> modifier to flatten
|
|
file names will make the archive readable by other C<ar> implementations
|
|
but not for linking because the symbol table format for LLVM is unique. If an
|
|
SVR4 or BSD style archive is used with the C<r> (replace) or C<q> (quick
|
|
update) operations, the archive will be reconstructed in LLVM format. This
|
|
means that the string table will be dropped (in deference to BSD 4.4 long names)
|
|
and an LLVM symbol table will be added (by default). The system symbol table
|
|
will be retained.
|
|
|
|
Here's where B<llvm-ar> departs from previous C<ar> implementations:
|
|
|
|
=over
|
|
|
|
=item I<Symbol Table>
|
|
|
|
Since B<llvm-ar> is intended to archive bytecode files, the symbol table
|
|
won't make much sense to anything but LLVM. Consequently, the symbol table's
|
|
format has been simplified. It consists simply of a sequence of pairs
|
|
of a file member index number as an LSB 4byte integer and a null-terminated
|
|
string.
|
|
|
|
=item I<Long Paths>
|
|
|
|
Some C<ar> implementations (SVR4) use a separate file member to record long
|
|
path names (> 15 characters). B<llvm-ar> takes the BSD 4.4 and Mac OS X
|
|
approach which is to simply store the full path name immediately preceding
|
|
the data for the file. The path name is null terminated and may contain the
|
|
slash (/) character.
|
|
|
|
=item I<Compression>
|
|
|
|
B<llvm-ar> can compress the members of an archive to save space. The
|
|
compression used depends on what's available on the platform and what choices
|
|
the LLVM Compressor utility makes. It generally favors bzip2 but will select
|
|
between "no compression" or bzip2 depending on what makes sense for the
|
|
file's content.
|
|
|
|
=item I<Directory Recursion>
|
|
|
|
Most C<ar> implementations do not recurse through directories but simply
|
|
ignore directories if they are presented to the program in the F<files>
|
|
option. B<llvm-ar>, however, can recurse through directory structures and
|
|
add all the files under a directory, if requested.
|
|
|
|
=item I<TOC Verbose Output>
|
|
|
|
When B<llvm-ar> prints out the verbose table of contents (C<tv> option), it
|
|
precedes the usual output with a character indicating the basic kind of
|
|
content in the file. A blank means the file is a regular file. A 'Z' means
|
|
the file is compressed. A 'B' means the file is an LLVM bytecode file. An
|
|
'S' means the file is the symbol table.
|
|
|
|
=back
|
|
|
|
=head1 OPTIONS
|
|
|
|
The options to B<llvm-ar> are compatible with other C<ar> implementations.
|
|
However, there are a few modifiers (F<zR>) that are not found in other
|
|
C<ar>s. The options to B<llvm-ar> specify a single basic operation to
|
|
perform on the archive, a variety of modifiers for that operation, the
|
|
name of the archive file, and an optional list of file names. These options
|
|
are used to determine how B<llvm-ar> should process the archive file.
|
|
|
|
The Operations and Modifiers are explained in the sections below. The minimal
|
|
set of options is at least one operator and the name of the archive. Typically
|
|
archive files end with a C<.a> suffix, but this is not required. Following
|
|
the F<archive-name> comes a list of F<files> that indicate the specific members
|
|
of the archive to operate on. If the F<files> option is not specified, it
|
|
generally means either "none" or "all" members, depending on the operation.
|
|
|
|
=head2 Operations
|
|
|
|
=over
|
|
|
|
=item d
|
|
|
|
Delete files from the archive. No modifiers are applicable to this operation.
|
|
The F<files> options specify which members should be removed from the
|
|
archive. It is not an error if a specified file does not appear in the archive.
|
|
If no F<files> are specified, the archive is not modified.
|
|
|
|
=item m[abi]
|
|
|
|
Move files from one location in the archive to another. The F<a>, F<b>, and
|
|
F<i> modifiers apply to this operation. The F<files> will all be moved
|
|
to the location given by the modifiers. If no modifiers are used, the files
|
|
will be moved to the end of the archive. If no F<files> are specified, the
|
|
archive is not modified.
|
|
|
|
=item p[k]
|
|
|
|
Print files to the standard output. The F<k> modifier applies to this
|
|
operation. This operation simply prints the F<files> indicated to the
|
|
standard output. If no F<files> are specified, the entire archive is printed.
|
|
Printing bytecode files is ill-advised as they might confuse your terminal
|
|
settings. The F<p> operation never modifies the archive.
|
|
|
|
=item q[Rfz]
|
|
|
|
Quickly append files to the end of the archive. The F<R>, F<f>, and F<z>
|
|
modifiers apply to this operation. This operation quickly adds the
|
|
F<files> to the archive without checking for duplicates that should be
|
|
removed first. If no F<files> are specified, the archive is not modified.
|
|
Because of the way that B<llvm-ar> constructs the archive file, its dubious
|
|
whether the F<q> operation is any faster than the F<r> operation.
|
|
|
|
=item r[Rabfuz]
|
|
|
|
Replace or insert file members. The F<R>, F<a>, F<b>, F<f>, F<u>, and F<z>
|
|
modifiers apply to this operation. This operation will replace existing
|
|
F<files> or insert them at the end of the archive if they do not exist. If no
|
|
F<files> are specified, the archive is not modified.
|
|
|
|
=item t[v]
|
|
|
|
Print the table of contents. Without any modifiers, this operation just prints
|
|
the names of the members to the standard output. With the F<v> modifier,
|
|
B<llvm-ar> also prints out the file type (B=bytecode, Z=compressed, S=symbol
|
|
table, blank=regular file), the permission mode, the owner and group, the
|
|
size, and the date. If any F<files> are specified, the listing is only for
|
|
those files. If no F<files> are specified, the table of contents for the
|
|
whole archive is printed.
|
|
|
|
=item x[oP]
|
|
|
|
Extract archive members back to files. The F<o> modifier applies to this
|
|
operation. This operation retrieves the indicated F<files> from the archive
|
|
and writes them back to the operating system's file system. If no
|
|
F<files> are specified, the entire archive is extract.
|
|
|
|
=back
|
|
|
|
=head2 Modifiers (operation specific)
|
|
|
|
The modifiers below are specific to certain operations. See the Operations
|
|
section (above) to determine which modifiers are applicable to which operations.
|
|
|
|
=over
|
|
|
|
=item [a]
|
|
|
|
When inserting or moving member files, this option specifies the destination of
|
|
the new files as being C<a>fter the F<relpos> member. If F<relpos> is not found,
|
|
the files are placed at the end of the archive.
|
|
|
|
=item [b]
|
|
|
|
When inserting or moving member files, this option specifies the destination of
|
|
the new files as being C<b>efore the F<relpos> member. If F<relpos> is not
|
|
found, the files are placed at the end of the archive. This modifier is
|
|
identical to the the F<i> modifier.
|
|
|
|
=item [f]
|
|
|
|
Normally, B<llvm-ar> stores the full path name to a file as presented to it on
|
|
the command line. With this option, truncated (15 characters max) names are
|
|
used. This ensures name compatibility with older versions of C<ar> but may also
|
|
thwart correct extraction of the files (duplicates may overwrite). If used with
|
|
the F<R> option, the directory recursion will be performed but the file names
|
|
will all be C<f>lattened to simple file names.
|
|
|
|
=item [i]
|
|
|
|
A synonym for the F<b> option.
|
|
|
|
=item [k]
|
|
|
|
Normally, B<llvm-ar> will not print the contents of bytecode files when the
|
|
F<p> operation is used. This modifier defeats the default and allows the
|
|
bytecode members to be printed.
|
|
|
|
=item [N]
|
|
|
|
This option is ignored by B<llvm-ar> but provided for compatibility.
|
|
|
|
=item [o]
|
|
|
|
When extracting files, this option will cause B<llvm-ar> to preserve the
|
|
original modification times of the files it writes.
|
|
|
|
=item [P]
|
|
|
|
use full path names when matching
|
|
|
|
=item [R]
|
|
|
|
This modifier instructions the F<r> option to recursively process directories.
|
|
Without F<R>, directories are ignored and only those F<files> that refer to
|
|
files will be added to the archive. When F<R> is used, any directories specified
|
|
with F<files> will be scanned (recursively) to find files to be added to the
|
|
archive. Any file whose name begins with a dot will not be added.
|
|
|
|
=item [u]
|
|
|
|
When replacing existing files in the archive, only replace those files that have
|
|
a time stamp than the time stamp of the member in the archive.
|
|
|
|
=item [z]
|
|
|
|
When inserting or replacing any file in the archive, compress the file first.
|
|
This
|
|
modifier is safe to use when (previously) compressed bytecode files are added to
|
|
the archive; the compressed bytecode files will not be doubly compressed.
|
|
|
|
=back
|
|
|
|
=head2 Modifiers (generic)
|
|
|
|
The modifiers below may be applied to any operation.
|
|
|
|
=over
|
|
|
|
=item [c]
|
|
|
|
For all operations, B<llvm-ar> will always create the archive if it doesn't
|
|
exist. Normally, B<llvm-ar> will print a warning message indicating that the
|
|
archive is being created. Using this modifier turns off that warning.
|
|
|
|
=item [s]
|
|
|
|
This modifier requests that an archive index (or symbol table) be added to the
|
|
archive. This is the default mode of operation. The symbol table will contain
|
|
all the externally visible functions and global variables defined by all the
|
|
bytecode files in the archive. Using this modifier is more efficient that using
|
|
L<llvm-ranlib|llvm-ranlib> which also creates the symbol table.
|
|
|
|
=item [S]
|
|
|
|
This modifier is the opposite of the F<s> modifier. It instructs B<llvm-ar> to
|
|
not build the symbol table. If both F<s> and F<S> are used, the last modifier to
|
|
occur in the options will prevail.
|
|
|
|
=item [v]
|
|
|
|
This modifier instructs B<llvm-ar> to be verbose about what it is doing. Each
|
|
editing operation taken against the archive will produce a line of output saying
|
|
what is being done.
|
|
|
|
=back
|
|
|
|
=head1 STANDARDS
|
|
|
|
The B<llvm-ar> utility is intended to provide a superset of the IEEE Std 1003.2
|
|
(POSIX.2) functionality for C<ar>. B<llvm-ar> can read both SVR4 and BSD4.4 (or
|
|
Mac OS X) archives. If the C<f> modifier is given to the C<x> or C<r> operations
|
|
then B<llvm-ar> will write SVR4 compatible archives. Without this modifier,
|
|
B<llvm-ar> will write BSD4.4 compatible archives that have long names
|
|
immediately after the header and indicated using the "#1/ddd" notation for the
|
|
name in the header.
|
|
|
|
=head1 FILE FORMAT
|
|
|
|
The file format for LLVM Archive files is similar to that of BSD 4.4 or Mac OSX
|
|
archive files. In fact, except for the symbol table, the C<ar> commands on those
|
|
operating systems should be able to read LLVM archive files. The details of the
|
|
file format follow.
|
|
|
|
Each archive begins with the archive magic number which is the eight printable
|
|
characters "!<arch>\n" where \n represents the newline character (0x0A).
|
|
Following the magic number, the file is composed of even length members that
|
|
begin with an archive header and end with a \n padding character if necessary
|
|
(to make the length even). Each file member is composed of a header (defined
|
|
below), an optional newline-terminated "long file name" and the contents of
|
|
the file.
|
|
|
|
The fields of the header are described in the items below. All fields of the
|
|
header contain only ASCII characters, are left justified and are right padded
|
|
with space characters.
|
|
|
|
=over
|
|
|
|
=item name - char[16]
|
|
|
|
This field of the header provides the name of the archive member. If the name is
|
|
longer than 15 characters or contains a slash (/) character, then this field
|
|
contains C<#1/nnn> where C<nnn> provides the length of the name and the C<#1/>
|
|
is literal. In this case, the actual name of the file is provided in the C<nnn>
|
|
bytes immediately following the header. If the name is 15 characters or less, it
|
|
is contained directly in this field and terminated with a slash (/) character.
|
|
|
|
=item date - char[12]
|
|
|
|
This field provides the date of modification of the file in the form of a
|
|
decimal encoded number that provides the number of seconds since the epoch
|
|
(since 00:00:00 Jan 1, 1970) per Posix specifications.
|
|
|
|
=item uid - char[6]
|
|
|
|
This field provides the user id of the file encoded as a decimal ASCII string.
|
|
This field might not make much sense on non-Unix systems. On Unix, it is the
|
|
same value as the st_uid field of the stat structure returned by the stat(2)
|
|
operating system call.
|
|
|
|
=item gid - char[6]
|
|
|
|
This field provides the group id of the file encoded as a decimal ASCII string.
|
|
This field might not make much sense on non-Unix systems. On Unix, it is the
|
|
same value as the st_gid field of the stat structure returned by the stat(2)
|
|
operating system call.
|
|
|
|
=item mode - char[8]
|
|
|
|
This field provides the access mode of the file encoded as an octal ASCII
|
|
string. This field might not make much sense on non-Unix systems. On Unix, it
|
|
is the same value as the st_mode field of the stat structure returned by the
|
|
stat(2) operating system call.
|
|
|
|
=item size - char[10]
|
|
|
|
This field provides the size of the file, in bytes, encoded as a decimal ASCII
|
|
string. If the size field is negative (starts with a minus sign, 0x02D), then
|
|
the archive member is stored in compressed form. The first byte of the archive
|
|
member's data indicates the compression type used. A value of 0 (0x30) indicates
|
|
that no compression was used. A value of 2 (0x32) indicates that bzip2
|
|
compression was used.
|
|
|
|
=item fmag - char[2]
|
|
|
|
This field is the archive file member magic number. Its content is always the
|
|
two characters back tick (0x60) and newline (0x0A). This provides some measure
|
|
utility in identifying archive files that have been corrupted.
|
|
|
|
=back
|
|
|
|
The LLVM symbol table has the special name "#_LLVM_SYM_TAB_#". It is presumed
|
|
that no regular archive member file will want this name. The LLVM symbol table
|
|
is simply composed of a sequence of triplets: byte offset, length of symbol,
|
|
and the symbol itself. Symbols are not null or newline terminated. Here are
|
|
the details on each of these items:
|
|
|
|
=over
|
|
|
|
=item offset - vbr encoded 32-bit integer
|
|
|
|
The offset item provides the offset into the archive file where the bytecode
|
|
member is stored that is associated with the symbol. The offset value is 0
|
|
based at the start of the first "normal" file member. To derive the actual
|
|
file offset of the member, you must add the number of bytes occupied by the file
|
|
signature (8 bytes) and the symbol tables. The value of this item is encoded
|
|
using variable bit rate encoding to reduce the size of the symbol table.
|
|
Variable bit rate encoding uses the high bit (0x80) of each byte to indicate
|
|
if there are more bytes to follow. The remaining 7 bits in each byte carry bits
|
|
from the value. The final byte does not have the high bit set.
|
|
|
|
=item length - vbr encoded 32-bit integer
|
|
|
|
The length item provides the length of the symbol that follows. Like this
|
|
I<offset> item, the length is variable bit rate encoded.
|
|
|
|
=item symbol - character array
|
|
|
|
The symbol item provides the text of the symbol that is associated with the
|
|
I<offset>. The symbol is not terminated by any character. Its length is provided
|
|
by the I<length> field. Note that is allowed (but unwise) to use non-printing
|
|
characters (even 0x00) in the symbol. This allows for multiple encodings of
|
|
symbol names.
|
|
|
|
=back
|
|
|
|
=head1 EXIT STATUS
|
|
|
|
If B<llvm-ar> succeeds, it will exit with 0. A usage error, results
|
|
in an exit code of 1. A hard (file system typically) error results in an
|
|
exit code of 2. Miscellaneous or unknown errors result in an
|
|
exit code of 3.
|
|
|
|
=head1 SEE ALSO
|
|
|
|
L<llvm-ranlib|llvm-ranlib>, ar(1)
|
|
|
|
=head1 AUTHORS
|
|
|
|
Maintained by the LLVM Team (L<http://llvm.org>).
|
|
|
|
=cut
|