end(3) — Subroutines
NAME
end, etext, edata, eprol, _ftext, _fdata, _fbss, _procedure_table, _procedure_table_size, _procedure_string_table − locations in program, runtime procedure table
SYNOPSIS
extern unsigned long _end;
extern unsigned long _etext;
extern unsigned long _edata;
extern unsigned long eprol;
extern unsigned long _ftext;
extern unsigned long _fdata;
extern unsigned long _fbss;
extern unsigned long _procedure_table;
extern unsigned long _procedure_table_size;
extern unsigned long _procedure_string_table;
extern unsigned long __istart;
extern unsigned long __fstart;
DESCRIPTION
These names refer neither to routines nor to locations with interesting contents except for _procedure_table, _procedure_string_table, and for DEC OSF/1, __istart and __fstart. Except for eprol, these are all names of loader defined symbols. The address of _etext is the first address above the program text, _edata is above the initialized data region, _end is above the uninitialized data region, and eprol is the first instruction of the user’s program that follows the runtime startup routine.
When execution begins, the program break coincides with _end, but it is reset by the routines brk(2), malloc(3), standard input/output (see stdio(3S)), the profile (−p) option of cc(1), etc. The current value of the program break is reliably returned by "sbrk(0)", (see brk(2)).
The loader defined symbols _procedure_table, _procedure_table_size, and _procedure_string_table refer to the data structures of the runtime procedure table. Since these are loader defined symbols the data structures are built by ld(1) only if they are referenced. See the include file sym.h for the definition of the runtime procedure table and see the include file exception.h for its uses.
The symbol _procedure_table_size is absolute symbol. The value of the symbol is its address (that is, "&_procedure_table_size"). Any reference to the symbol itself will attempt to access the symbol’s value as if it were a valid address. This will most likely result in an access violation.