extern struct dyld_info_command [src]

The dyld_info_command contains the file offsets and sizes of the new compressed form of the information dyld needs to load the image. This information is used by dyld on Mac OS X 10.6 and later. All information pointed to by this command is encoded using byte streams, so no endian swapping is needed to interpret it.

Fields

cmd: LC = .DYLD_INFO_ONLYLC_DYLD_INFO or LC_DYLD_INFO_ONLY

cmdsize: u32 = @sizeOf(dyld_info_command)sizeof(struct dyld_info_command)

rebase_off: u32 = 0file offset to rebase info

rebase_size: u32 = 0size of rebase info

bind_off: u32 = 0file offset to binding info

bind_size: u32 = 0size of binding info

weak_bind_off: u32 = 0file offset to weak binding info

weak_bind_size: u32 = 0size of weak binding info

lazy_bind_off: u32 = 0file offset to lazy binding info

lazy_bind_size: u32 = 0size of lazy binding info

export_off: u32 = 0file offset to lazy binding info

export_size: u32 = 0size of lazy binding info

Source

  pub const dyld_info_command = extern struct {
    /// LC_DYLD_INFO or LC_DYLD_INFO_ONLY
    cmd: LC = .DYLD_INFO_ONLY,

    /// sizeof(struct dyld_info_command)
    cmdsize: u32 = @sizeOf(dyld_info_command),

    // Dyld rebases an image whenever dyld loads it at an address different
    // from its preferred address.  The rebase information is a stream
    // of byte sized opcodes whose symbolic names start with REBASE_OPCODE_.
    // Conceptually the rebase information is a table of tuples:
    //    
    // The opcodes are a compressed way to encode the table by only
    // encoding when a column changes.  In addition simple patterns
    // like "every n'th offset for m times" can be encoded in a few
    // bytes.

    /// file offset to rebase info
    rebase_off: u32 = 0,

    /// size of rebase info
    rebase_size: u32 = 0,

    // Dyld binds an image during the loading process, if the image
    // requires any pointers to be initialized to symbols in other images.
    // The bind information is a stream of byte sized
    // opcodes whose symbolic names start with BIND_OPCODE_.
    // Conceptually the bind information is a table of tuples:
    //    
    // The opcodes are a compressed way to encode the table by only
    // encoding when a column changes.  In addition simple patterns
    // like for runs of pointers initialized to the same value can be
    // encoded in a few bytes.

    /// file offset to binding info
    bind_off: u32 = 0,

    /// size of binding info
    bind_size: u32 = 0,

    // Some C++ programs require dyld to unique symbols so that all
    // images in the process use the same copy of some code/data.
    // This step is done after binding. The content of the weak_bind
    // info is an opcode stream like the bind_info.  But it is sorted
    // alphabetically by symbol name.  This enable dyld to walk
    // all images with weak binding information in order and look
    // for collisions.  If there are no collisions, dyld does
    // no updating.  That means that some fixups are also encoded
    // in the bind_info.  For instance, all calls to "operator new"
    // are first bound to libstdc++.dylib using the information
    // in bind_info.  Then if some image overrides operator new
    // that is detected when the weak_bind information is processed
    // and the call to operator new is then rebound.

    /// file offset to weak binding info
    weak_bind_off: u32 = 0,

    /// size of weak binding info
    weak_bind_size: u32 = 0,

    // Some uses of external symbols do not need to be bound immediately.
    // Instead they can be lazily bound on first use.  The lazy_bind
    // are contains a stream of BIND opcodes to bind all lazy symbols.
    // Normal use is that dyld ignores the lazy_bind section when
    // loading an image.  Instead the static linker arranged for the
    // lazy pointer to initially point to a helper function which
    // pushes the offset into the lazy_bind area for the symbol
    // needing to be bound, then jumps to dyld which simply adds
    // the offset to lazy_bind_off to get the information on what
    // to bind.

    /// file offset to lazy binding info
    lazy_bind_off: u32 = 0,

    /// size of lazy binding info
    lazy_bind_size: u32 = 0,

    // The symbols exported by a dylib are encoded in a trie.  This
    // is a compact representation that factors out common prefixes.
    // It also reduces LINKEDIT pages in RAM because it encodes all
    // information (name, address, flags) in one small, contiguous range.
    // The export area is a stream of nodes.  The first node sequentially
    // is the start node for the trie.
    //
    // Nodes for a symbol start with a uleb128 that is the length of
    // the exported symbol information for the string so far.
    // If there is no exported symbol, the node starts with a zero byte.
    // If there is exported info, it follows the length.
    //
    // First is a uleb128 containing flags. Normally, it is followed by
    // a uleb128 encoded offset which is location of the content named
    // by the symbol from the mach_header for the image.  If the flags
    // is EXPORT_SYMBOL_FLAGS_REEXPORT, then following the flags is
    // a uleb128 encoded library ordinal, then a zero terminated
    // UTF8 string.  If the string is zero length, then the symbol
    // is re-export from the specified dylib with the same name.
    // If the flags is EXPORT_SYMBOL_FLAGS_STUB_AND_RESOLVER, then following
    // the flags is two uleb128s: the stub offset and the resolver offset.
    // The stub is used by non-lazy pointers.  The resolver is used
    // by lazy pointers and must be called to get the actual address to use.
    //
    // After the optional exported symbol information is a byte of
    // how many edges (0-255) that this node has leaving it,
    // followed by each edge.
    // Each edge is a zero terminated UTF8 of the addition chars
    // in the symbol, followed by a uleb128 offset for the node that
    // edge points to.

    /// file offset to lazy binding info
    export_off: u32 = 0,

    /// size of lazy binding info
    export_size: u32 = 0,
}  