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