Version Definition Section

This section is defined by the type SHT_SUNW_verdef. If this section exists, a SHT_SUNW_versym section must also exist. Using these two structures, an association of symbols-to-version definitions is maintained within the file. See “Creating a Version Definition”. Elements of this section have the following structure:

typedef struct {
        Elf32_Half      vd_version;
        Elf32_Half      vd_flags;
        Elf32_Half      vd_ndx;
        Elf32_Half      vd_cnt;
        Elf32_Word      vd_hash;
        Elf32_Word      vd_aux;
        Elf32_Word      vd_next;
} Elf32_Verdef;
 
typedef struct {
        Elf32_Word      vda_name;
        Elf32_Word      vda_next;
} Elf32_Verdaux;

typedef struct {
        Elf64_Half      vd_version;
        Elf64_Half      vd_flags;
        Elf64_Half      vd_ndx;
        Elf64_Half      vd_cnt;
        Elf64_Word      vd_hash;
        Elf64_Word      vd_aux;
        Elf64_Word      vd_next;
} Elf64_Verdef;
 
typedef struct {
        Elf64_Word      vda_name;
        Elf64_Word      vda_next;
} Elf64_Verdaux;

The elements of this structure are:

vd_version

This member identifies the version of the structure itself, as listed in the following table.

Table 7-30 ELF Version Definition Structure Versions

Name	Value	Meaning
VER_DEF_NONE	0	Invalid version.
VER_DEF_CURRENT	>=1	Current version.

The value 1 signifies the original section format. Extensions will create new versions with higher numbers. The value of VER_DEF_CURRENT changes as necessary to reflect the current version number.

vd_flags

This member holds version definition-specific information, as listed in the following table.

Table 7-31 ELF Version Definition Section Flags

Name	Value	Meaning
VER_FLG_BASE	0x1	Version definition of the file itself.
VER_FLG_WEAK	0x2	Weak version identifier.

The base version definition is always present when version definitions, or symbol auto-reduction, have been applied to the file. The base version provides a default version for the files reserved symbols. A weak version definition has no symbols associated with it. See “Creating a Weak Version Definition”.

vd_ndx

The version index. Each version definition has a unique index that is used to associate SHT_SUNW_versym entries to the appropriate version definition.

vd_cnt

The number of elements in the Elf32_Verdaux array.

vd_hash

The hash value of the version definition name. This value is generated using the same hashing function described in “Hash Table”.

vd_aux

The byte offset from the start of this Elf32_Verdef entry to the Elf32_Verdaux array of version definition names. The first element of the array must exist. It points to the version definition string this structure defines. Additional elements can be present. The number of elements is indicated by the vd_cnt value. These elements represent the dependencies of this version definition. Each of these dependencies will have its own version definition structure.

vd_next

The byte offset from the start of this Elf32_Verdef structure to the next Elf32_Verdef entry.

vda_name

The string table offset to a null-terminated string, giving the name of the version definition.

vda_next

The byte offset from the start of this Elf32_Verdaux entry to the next Elf32_Verdaux entry.