ELF Object File Format

4. String Table

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 would contain zero. Non-zero 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.

Figure 4.1 Example String Table

Table 4.1 String Table Indexes

Index	String
0	none
1	“name.”
7	“Variable”
11	“able”
16	“able”
22	“xx”
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.