NAME
dwarf_get_fde_info_for_reg3 —
retrieve
register rule
LIBRARY
DWARF Access Library (libdwarf, -ldwarf)
SYNOPSIS
#include <libdwarf.h>
int
dwarf_get_fde_info_for_reg3(
Dwarf_Fde
fde,
Dwarf_Half table_column,
Dwarf_Addr pc,
Dwarf_Small *type,
Dwarf_Signed *offset_relevant,
Dwarf_Signed *register_num,
Dwarf_Signed
*offset_or_block_len,
Dwarf_Ptr *block_ptr,
Dwarf_Addr *row_pc,
Dwarf_Error
*error);
DESCRIPTION
Function
dwarf_get_fde_info_for_reg3() retrieves a register
rule from the register rule table associated with a given FDE descriptor,
given a program counter address and rule column number.
Argument
fde should reference a valid DWARF FDE
descriptor.
Arugment
table_column should hold the column number of the
register rule desired.
Argument
pc should hold the program counter address to be
used to locate the desired register rule row.
On successful execution,
dwarf_get_fde_info_for_reg3() stores
information about the register rule found into the locations pointed to by the
arguments
type,
offset_relevant,
register_num,
offset_or_block_len,
block_ptr and
row_pc.
Argument
type should point to a location which will hold
the type code of the register rule found. The returned value is one of the
DW_EXPR_*
contants defined in the header file
<libdwarf.h>.
If there is an offset value associated with the register rule, the location
pointed to by argument
offset_relevant will be set to 1.
Argument
register_num should point to a location which
will hold the register number associated with the register rule.
If the register rule is of type
DW_EXPR_OFFSET
or
DW_EXPR_VAL_OFFSET
, the location pointed to by
argument
offset_or_block_len will be set to the offset
value associated with the register rule, or to 0 if the register rule does not
have an offset value. If the type code is
DW_EXPR_EXPRESSION
or
DW_EXPR_VAL_EXPRESSION
, the location pointed to by
argument
offset_or_block_len will be set to the length
in bytes of the DWARF expression block associated with the register rule.
Argument
block_ptr should point to a location which will
be set to a pointer to the content of the DWARF expression block associated
with the register rule.
Argument
row_pc should point to a location which will be
set to the lowest program counter address associated with the register rule
found.
If argument
err is not NULL, it will be used to return an
error descriptor in case of an error.
RETURN VALUES
Function
dwarf_get_fde_info_for_reg3() returns
DW_DLV_OK
when it succeeds. In case of an error, it
returns
DW_DLV_ERROR
and sets the argument
err.
ERRORS
Function
dwarf_get_fde_info_for_reg3() can fail with:
-
-
- [
DW_DLE_ARGUMENT
]
- One of the arguments block_ptr,
fde, offset_or_block_len,
offset_relevant, register_num,
row_pc, or type was NULL.
-
-
- [
DW_DLE_FRAME_TABLE_COL_BAD
]
- The column number provided in argument
table_column was too large.
-
-
- [
DW_DLE_PC_NOT_IN_FDE_RANGE
]
- The program counter value provided in argument
pc did not fall in the range covered by argument
fde.
EXAMPLE
To retrieve the register rules at column 3 from a rule table associated with a
FDE descriptor:
Dwarf_Fde fde;
Dwarf_Off fde_offset, cie_offset;
Dwarf_Unsigned func_len, fde_length;
Dwarf_Signed cie_index, offset_relevant, register_num;
Dwarf_Signed offset_or_block_len;
Dwarf_Addr low_pc, row_pc;
Dwarf_Ptr fde_addr, block_ptr;
Dwarf_Small type;
Dwarf_Error de;
/* ... assuming `fde` references a valid FDE descriptor... */
if (dwarf_get_fde_range(fde, &low_pc, &func_len, &fde_addr,
&fde_length, &cie_offset, &cie_index, &fde_offset,
&de) != DW_DLV_OK)
errx(EXIT_FAILURE, "dwarf_get_fde_range failed: %s",
dwarf_errmsg(de));
/* Iterate all the table rows. */
for (pc = low_pc; pc < low_pc + func_len; pc++) {
if (dwarf_get_fde_info_for_reg3(fde, 3, pc, &type,
&offset_relevant, ®ister_num, &offset_or_block_len,
&block_ptr, &row_pc, &de) != DW_DLV_OK) {
warnx("dwarf_get_fde_info_for_reg3 failed: %s",
dwarf_errmsg(de));
continue;
}
/* ... use the retrieved register rule ... */
}
SEE ALSO
dwarf(3),
dwarf_get_fde_at_pc(3),
dwarf_get_fde_info_for_all_regs(3),
dwarf_get_fde_info_for_all_regs3(3),
dwarf_get_fde_info_for_cfa_reg3(3),
dwarf_get_fde_info_for_reg(3),
dwarf_get_fde_n(3),
dwarf_set_frame_cfa_value(3),
dwarf_set_frame_rule_table_size(3),
dwarf_set_frame_rule_initial_value(3),
dwarf_set_frame_same_value(3),
dwarf_set_frame_undefined_value(3)