1.\" Copyright (c) 2011 Kai Wang 2.\" All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 13.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 14.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 15.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 16.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 17.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 18.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 19.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 20.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 21.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 22.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 23.\" SUCH DAMAGE. 24.\" 25.\" $Id: dwarf_get_fde_info_for_reg3.3 3644 2018-10-15 19:55:01Z jkoshy $ 26.\" 27.Dd November 9, 2011 28.Dt DWARF_GET_FDE_INFO_FOR_REG3 3 29.Os 30.Sh NAME 31.Nm dwarf_get_fde_info_for_reg3 32.Nd retrieve register rule 33.Sh LIBRARY 34.Lb libdwarf 35.Sh SYNOPSIS 36.In libdwarf.h 37.Ft int 38.Fo dwarf_get_fde_info_for_reg3 39.Fa "Dwarf_Fde fde" 40.Fa "Dwarf_Half table_column" 41.Fa "Dwarf_Addr pc" 42.Fa "Dwarf_Small *type" 43.Fa "Dwarf_Signed *offset_relevant" 44.Fa "Dwarf_Signed *register_num" 45.Fa "Dwarf_Signed *offset_or_block_len" 46.Fa "Dwarf_Ptr *block_ptr" 47.Fa "Dwarf_Addr *row_pc" 48.Fa "Dwarf_Error *error" 49.Fc 50.Sh DESCRIPTION 51Function 52.Fn dwarf_get_fde_info_for_reg3 53retrieves a register rule from the register rule table associated with 54a given FDE descriptor, given a program counter address and rule 55column number. 56.Pp 57Argument 58.Ar fde 59should reference a valid DWARF FDE descriptor. 60.Pp 61Arugment 62.Ar table_column 63should hold the column number of the register rule desired. 64.Pp 65Argument 66.Ar pc 67should hold the program counter address to be used to locate the 68desired register rule row. 69.Pp 70On successful execution, 71.Fn dwarf_get_fde_info_for_reg3 72stores information about the register rule found into the locations 73pointed to by the arguments 74.Ar type , 75.Ar offset_relevant , 76.Ar register_num , 77.Ar offset_or_block_len , 78.Ar block_ptr 79and 80.Ar row_pc . 81.Pp 82Argument 83.Ar type 84should point to a location which will hold the type code of the 85register rule found. 86The returned value is one of the 87.Dv DW_EXPR_* 88contants defined in the header file 89.In libdwarf.h . 90.Pp 91If there is an offset value associated with the register rule, 92the location pointed to by argument 93.Ar offset_relevant 94will be set to 1. 95.Pp 96Argument 97.Ar register_num 98should point to a location which will hold the register number associated 99with the register rule. 100.Pp 101If the register rule is of type 102.Dv DW_EXPR_OFFSET 103or 104.Dv DW_EXPR_VAL_OFFSET , 105the location pointed to by argument 106.Ar offset_or_block_len 107will be set to the offset value associated with the register rule, 108or to 0 if the register rule does not have an offset value. 109If the type code is 110.Dv DW_EXPR_EXPRESSION 111or 112.Dv DW_EXPR_VAL_EXPRESSION , 113the location pointed to by argument 114.Ar offset_or_block_len 115will be set to the length in bytes of the DWARF expression block 116associated with the register rule. 117.Pp 118Argument 119.Ar block_ptr 120should point to a location which will be set to a pointer to the 121content of the DWARF expression block associated with the register 122rule. 123.Pp 124Argument 125.Ar row_pc 126should point to a location which will be set to the lowest program 127counter address associated with the register rule found. 128.Pp 129If argument 130.Ar err 131is not NULL, it will be used to return an error descriptor in case 132of an error. 133.Sh RETURN VALUES 134Function 135.Fn dwarf_get_fde_info_for_reg3 136returns 137.Dv DW_DLV_OK 138when it succeeds. 139In case of an error, it returns 140.Dv DW_DLV_ERROR 141and sets the argument 142.Ar err . 143.Sh EXAMPLES 144To retrieve the register rules at column 3 from a rule table 145associated with a FDE descriptor: 146.Bd -literal -offset indent 147Dwarf_Fde fde; 148Dwarf_Off fde_offset, cie_offset; 149Dwarf_Unsigned func_len, fde_length; 150Dwarf_Signed cie_index, offset_relevant, register_num; 151Dwarf_Signed offset_or_block_len; 152Dwarf_Addr low_pc, row_pc; 153Dwarf_Ptr fde_addr, block_ptr; 154Dwarf_Small type; 155Dwarf_Error de; 156 157/* ... assuming `fde` references a valid FDE descriptor... */ 158if (dwarf_get_fde_range(fde, &low_pc, &func_len, &fde_addr, 159 &fde_length, &cie_offset, &cie_index, &fde_offset, 160 &de) != DW_DLV_OK) 161 errx(EXIT_FAILURE, "dwarf_get_fde_range failed: %s", 162 dwarf_errmsg(de)); 163 164/* Iterate all the table rows. */ 165for (pc = low_pc; pc < low_pc + func_len; pc++) { 166 if (dwarf_get_fde_info_for_reg3(fde, 3, pc, &type, 167 &offset_relevant, ®ister_num, &offset_or_block_len, 168 &block_ptr, &row_pc, &de) != DW_DLV_OK) { 169 warnx("dwarf_get_fde_info_for_reg3 failed: %s", 170 dwarf_errmsg(de)); 171 continue; 172 } 173 /* ... use the retrieved register rule ... */ 174} 175.Ed 176.Sh ERRORS 177Function 178.Fn dwarf_get_fde_info_for_reg3 179can fail with: 180.Bl -tag -width ".Bq Er DW_DLE_FRAME_TABLE_COL_BAD" 181.It Bq Er DW_DLE_ARGUMENT 182One of the arguments 183.Ar block_ptr , 184.Ar fde , 185.Ar offset_or_block_len , 186.Ar offset_relevant , 187.Ar register_num , 188.Ar row_pc , 189or 190.Ar type 191was NULL. 192.It Bq Er DW_DLE_FRAME_TABLE_COL_BAD 193The column number provided in argument 194.Ar table_column 195was too large. 196.It Bq Er DW_DLE_PC_NOT_IN_FDE_RANGE 197The program counter value provided in argument 198.Ar pc 199did not fall in the range covered by argument 200.Ar fde . 201.El 202.Sh SEE ALSO 203.Xr dwarf 3 , 204.Xr dwarf_get_fde_at_pc 3 , 205.Xr dwarf_get_fde_info_for_all_regs 3 , 206.Xr dwarf_get_fde_info_for_all_regs3 3 , 207.Xr dwarf_get_fde_info_for_cfa_reg3 3 , 208.Xr dwarf_get_fde_info_for_reg 3 , 209.Xr dwarf_get_fde_n 3 , 210.Xr dwarf_set_frame_cfa_value 3 , 211.Xr dwarf_set_frame_rule_initial_value 3 , 212.Xr dwarf_set_frame_rule_table_size 3 , 213.Xr dwarf_set_frame_same_value 3 , 214.Xr dwarf_set_frame_undefined_value 3 215