String table sections hold null-terminated character sequences, commonly called strings. The object file uses these strings to represent symbol and section names. One references a string as an index into the string table section.
The first byte, which is index zero, is defined to hold a null character. Likewise, a string table's last byte is defined to hold a null character, ensuring null termination for all strings. A string whose index is zero specifies either no name or a null name, depending on the context.
An empty string table section is permitted; its section header's sh_size member will contain zero. Nonzero indexes are invalid for an empty string table.
A section header's sh_name member holds an index into the section header string table section, as designated by the e_shstrndx member of the ELF header. The following figures show a string table with 25 bytes and the strings associated with various indexes.
The table below shows the strings of the string table above:
Table 7-15 String Table Indexes
Index |
String |
---|---|
0 |
none |
1 |
name. |
7 |
Variable |
11 |
able |
16 |
able |
24 |
null string |
As the example shows, a string table index may refer to any byte in the section. A string may appear more than once; references to substrings may exist; and a single string may be referenced multiple times. Unreferenced strings also are allowed.