Commit 04361dd461
Changed files (1)
lib
std
lib/std/macho.zig
@@ -81,6 +81,182 @@ pub const symtab_command = extern struct {
strsize: u32,
};
+/// This is the second set of the symbolic information which is used to support
+/// the data structures for the dynamically link editor.
+///
+/// The original set of symbolic information in the symtab_command which contains
+/// the symbol and string tables must also be present when this load command is
+/// present. When this load command is present the symbol table is organized
+/// into three groups of symbols:
+/// local symbols (static and debugging symbols) - grouped by module
+/// defined external symbols - grouped by module (sorted by name if not lib)
+/// undefined external symbols (sorted by name if MH_BINDATLOAD is not set,
+/// and in order the were seen by the static
+/// linker if MH_BINDATLOAD is set)
+/// In this load command there are offsets and counts to each of the three groups
+/// of symbols.
+///
+/// This load command contains a the offsets and sizes of the following new
+/// symbolic information tables:
+/// table of contents
+/// module table
+/// reference symbol table
+/// indirect symbol table
+/// The first three tables above (the table of contents, module table and
+/// reference symbol table) are only present if the file is a dynamically linked
+/// shared library. For executable and object modules, which are files
+/// containing only one module, the information that would be in these three
+/// tables is determined as follows:
+/// table of contents - the defined external symbols are sorted by name
+/// module table - the file contains only one module so everything in the
+/// file is part of the module.
+/// reference symbol table - is the defined and undefined external symbols
+///
+/// For dynamically linked shared library files this load command also contains
+/// offsets and sizes to the pool of relocation entries for all sections
+/// separated into two groups:
+/// external relocation entries
+/// local relocation entries
+/// For executable and object modules the relocation entries continue to hang
+/// off the section structures.
+pub const dysymtab_command = extern struct {
+ /// LC_DYSYMTAB
+ cmd: u32,
+
+ /// sizeof(struct dysymtab_command)
+ cmdsize: u32,
+
+ // The symbols indicated by symoff and nsyms of the LC_SYMTAB load command
+ // are grouped into the following three groups:
+ // local symbols (further grouped by the module they are from)
+ // defined external symbols (further grouped by the module they are from)
+ // undefined symbols
+ //
+ // The local symbols are used only for debugging. The dynamic binding
+ // process may have to use them to indicate to the debugger the local
+ // symbols for a module that is being bound.
+ //
+ // The last two groups are used by the dynamic binding process to do the
+ // binding (indirectly through the module table and the reference symbol
+ // table when this is a dynamically linked shared library file).
+
+ /// index of local symbols
+ ilocalsym: u32,
+
+ /// number of local symbols
+ nlocalsym: u32,
+
+ /// index to externally defined symbols
+ iextdefsym: u32,
+
+ /// number of externally defined symbols
+ nextdefsym: u32,
+
+ /// index to undefined symbols
+ iundefsym: u32,
+
+ /// number of undefined symbols
+ nundefsym: u32,
+
+ // For the for the dynamic binding process to find which module a symbol
+ // is defined in the table of contents is used (analogous to the ranlib
+ // structure in an archive) which maps defined external symbols to modules
+ // they are defined in. This exists only in a dynamically linked shared
+ // library file. For executable and object modules the defined external
+ // symbols are sorted by name and is use as the table of contents.
+
+ /// file offset to table of contents
+ tocoff: u32,
+
+ /// number of entries in table of contents
+ ntoc: u32,
+
+ // To support dynamic binding of "modules" (whole object files) the symbol
+ // table must reflect the modules that the file was created from. This is
+ // done by having a module table that has indexes and counts into the merged
+ // tables for each module. The module structure that these two entries
+ // refer to is described below. This exists only in a dynamically linked
+ // shared library file. For executable and object modules the file only
+ // contains one module so everything in the file belongs to the module.
+
+ /// file offset to module table
+ modtaboff: u32,
+
+ /// number of module table entries
+ nmodtab: u32,
+
+ // To support dynamic module binding the module structure for each module
+ // indicates the external references (defined and undefined) each module
+ // makes. For each module there is an offset and a count into the
+ // reference symbol table for the symbols that the module references.
+ // This exists only in a dynamically linked shared library file. For
+ // executable and object modules the defined external symbols and the
+ // undefined external symbols indicates the external references.
+
+ /// offset to referenced symbol table
+ extrefsymoff: u32,
+
+ /// number of referenced symbol table entries
+ nextrefsyms: u32,
+
+ // The sections that contain "symbol pointers" and "routine stubs" have
+ // indexes and (implied counts based on the size of the section and fixed
+ // size of the entry) into the "indirect symbol" table for each pointer
+ // and stub. For every section of these two types the index into the
+ // indirect symbol table is stored in the section header in the field
+ // reserved1. An indirect symbol table entry is simply a 32bit index into
+ // the symbol table to the symbol that the pointer or stub is referring to.
+ // The indirect symbol table is ordered to match the entries in the section.
+
+ /// file offset to the indirect symbol table
+ indirectsymoff: u32,
+
+ /// number of indirect symbol table entries
+ nindirectsyms: u32,
+
+ // To support relocating an individual module in a library file quickly the
+ // external relocation entries for each module in the library need to be
+ // accessed efficiently. Since the relocation entries can't be accessed
+ // through the section headers for a library file they are separated into
+ // groups of local and external entries further grouped by module. In this
+ // case the presents of this load command who's extreloff, nextrel,
+ // locreloff and nlocrel fields are non-zero indicates that the relocation
+ // entries of non-merged sections are not referenced through the section
+ // structures (and the reloff and nreloc fields in the section headers are
+ // set to zero).
+ //
+ // Since the relocation entries are not accessed through the section headers
+ // this requires the r_address field to be something other than a section
+ // offset to identify the item to be relocated. In this case r_address is
+ // set to the offset from the vmaddr of the first LC_SEGMENT command.
+ // For MH_SPLIT_SEGS images r_address is set to the the offset from the
+ // vmaddr of the first read-write LC_SEGMENT command.
+ //
+ // The relocation entries are grouped by module and the module table
+ // entries have indexes and counts into them for the group of external
+ // relocation entries for that the module.
+ //
+ // For sections that are merged across modules there must not be any
+ // remaining external relocation entries for them (for merged sections
+ // remaining relocation entries must be local).
+
+ /// offset to external relocation entries
+ extreloff: u32,
+
+ /// number of external relocation entries
+ nextrel: u32,
+
+ // All the local relocation entries are grouped together (they are not
+ // grouped by their module since they are only used if the object is moved
+ // from it staticly link edited address).
+
+ /// offset to local relocation entries
+ locreloff: u32,
+
+ /// number of local relocation entries
+ nlocrel: u32,
+};
+
/// The linkedit_data_command contains the offsets and sizes of a blob
/// of data in the __LINKEDIT segment.
pub const linkedit_data_command = extern struct {
@@ -97,6 +273,127 @@ pub const linkedit_data_command = extern struct {
datasize: u32,
};
+/// 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.
+pub const dyld_info_command = extern struct {
+ /// LC_DYLD_INFO or LC_DYLD_INFO_ONLY
+ cmd: u32,
+
+ /// sizeof(struct dyld_info_command)
+ cmdsize: u32,
+
+ // 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:
+ // <seg-index, seg-offset, type>
+ // 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,
+
+ /// size of rebase info
+ rebase_size: u32,
+
+ // 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:
+ // <seg-index, seg-offset, type, symbol-library-ordinal, symbol-name, addend>
+ // 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 initialzed to the same value can be
+ // encoded in a few bytes.
+
+ /// file offset to binding info
+ bind_off: u32,
+
+ /// size of binding info
+ bind_size: u32,
+
+ // 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,
+
+ /// size of weak binding info
+ weak_bind_size: u32,
+
+ // 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,
+
+ /// size of lazy binding info
+ lazy_bind_size: u32,
+
+ // 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,
+
+ /// size of lazy binding info
+ export_size: u32,
+};
+
/// A program that uses a dynamic linker contains a dylinker_command to identify
/// the name of the dynamic linker (LC_LOAD_DYLINKER). And a dynamic linker
/// contains a dylinker_command to identify the dynamic linker (LC_ID_DYLINKER).
@@ -681,6 +978,24 @@ pub const N_TYPE = 0x0e;
/// external symbol bit, set for external symbols
pub const N_EXT = 0x01;
+/// symbol is undefined
+pub const N_UNDF = 0x0;
+
+/// symbol is absolute
+pub const N_ABS = 0x2;
+
+/// symbol is defined in the section number given in n_sect
+pub const N_SECT = 0xe;
+
+/// symbol is undefined and the image is using a prebound
+/// value for the symbol
+pub const N_PBUD = 0xc;
+
+/// symbol is defined to be the same as another symbol; the n_value
+/// field is an index into the string table specifying the name of the
+/// other symbol
+pub const N_INDR = 0xa;
+
/// global symbol: name,,NO_SECT,type,0
pub const N_GSYM = 0x20;
@@ -781,6 +1096,35 @@ pub const N_LENG = 0xfe;
/// a debug section
pub const S_ATTR_DEBUG = 0x02000000;
+/// section contains only true machine instructions
+pub const S_ATTR_PURE_INSTRUCTIONS = 0x80000000;
+
+/// section contains coalesced symbols that are not to be in a ranlib
+/// table of contents
+pub const S_ATTR_NO_TOC = 0x40000000;
+
+/// ok to strip static symbols in this section in files with the
+/// MH_DYLDLINK flag
+pub const S_ATTR_STRIP_STATIC_SYMS = 0x20000000;
+
+/// no dead stripping
+pub const S_ATTR_NO_DEAD_STRIP = 0x10000000;
+
+/// blocks are live if they reference live blocks
+pub const S_ATTR_LIVE_SUPPORT = 0x8000000;
+
+/// used with i386 code stubs written on by dyld
+pub const S_ATTR_SELF_MODIFYING_CODE = 0x4000000;
+
+/// section contains some machine instructions
+pub const S_ATTR_SOME_INSTRUCTIONS = 0x400;
+
+/// section has external relocation entries
+pub const S_ATTR_EXT_RELOC = 0x200;
+
+/// section has local relocation entries
+pub const S_ATTR_LOC_RELOC = 0x100;
+
pub const cpu_type_t = integer_t;
pub const cpu_subtype_t = integer_t;
pub const integer_t = c_int;