1.\" $NetBSD: dwarf_add_expr_gen.3,v 1.6 2024/03/03 17:37:30 christos Exp $ 2.\" 3.\" Copyright (c) 2011 Kai Wang 4.\" All rights reserved. 5.\" 6.\" Redistribution and use in source and binary forms, with or without 7.\" modification, are permitted provided that the following conditions 8.\" are met: 9.\" 1. Redistributions of source code must retain the above copyright 10.\" notice, this list of conditions and the following disclaimer. 11.\" 2. Redistributions in binary form must reproduce the above copyright 12.\" notice, this list of conditions and the following disclaimer in the 13.\" documentation and/or other materials provided with the distribution. 14.\" 15.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 16.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 17.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 18.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 19.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 20.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 21.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 22.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 23.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 24.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 25.\" SUCH DAMAGE. 26.\" 27.\" Id: dwarf_add_expr_gen.3 3961 2022-03-12 15:13:22Z jkoshy 28.\" 29.Dd September 9, 2011 30.Dt DWARF_ADD_EXPR_GEN 3 31.Os 32.Sh NAME 33.Nm dwarf_add_expr_gen 34.Nd add an operator to a location expression descriptor 35.Sh LIBRARY 36.Lb libdwarf 37.Sh SYNOPSIS 38.In libdwarf.h 39.Ft "Dwarf_Unsigned" 40.Fo dwarf_add_expr_gen 41.Fa "Dwarf_P_Expr expr" 42.Fa "Dwarf_Small opcode" 43.Fa "Dwarf_Unsigned val1" 44.Fa "Dwarf_Unsigned val2" 45.Fa "Dwarf_Error *err" 46.Fc 47.Sh DESCRIPTION 48Function 49.Fn dwarf_add_expr_gen 50adds a location expression operator to the location expression 51descriptor referenced by argument 52.Fa expr . 53.Pp 54Argument 55.Fa expr 56should reference a location expression descriptor allocated using 57the function 58.Xr dwarf_new_expr 3 . 59.Pp 60Argument 61.Fa opcode 62specifies the operation code of the location expression operator. 63Valid values for this argument are those denoted by the 64.Dv DW_OP_ Ns * 65constants defined in 66.In libdwarf.h . 67.Pp 68To generate a 69.Dv DW_OP_addr 70operation, application code should instead use 71.Xr dwarf_add_expr_addr_b 3 . 72.Pp 73Argument 74.Fa val1 75specifies the first operand of the location expression operator. 76.Pp 77Argument 78.Fa val2 79specifies the second operand of the location expression operator. 80.Pp 81If argument 82.Fa err 83is not 84.Dv NULL , 85it will be used to store error information in case of an error. 86.Sh RETURN VALUES 87On success, function 88.Fn dwarf_add_expr_gen 89returns the size in bytes of the location expression byte stream 90generated. 91In case of an error, function 92.Fn dwarf_add_expr_gen 93returns 94.Dv DW_DLV_NOCOUNT 95and sets the argument 96.Fa err . 97.Sh ERRORS 98Function 99.Fn dwarf_add_expr_gen 100can fail with: 101.Bl -tag -width ".Bq Er DW_DLE_LOC_EXPR_BAD" 102.It Bq Er DW_DLE_ARGUMENT 103Argument 104.Fa expr 105was 106.Dv NULL . 107.It Bq Er DW_DLE_LOC_EXPR_BAD 108The operation code specified in argument 109.Fa opcode 110was invalid. 111.It Bq Er DW_DLE_MEMORY 112An out of memory condition was encountered during the execution of 113the function. 114.El 115.Sh SEE ALSO 116.Xr dwarf 3 , 117.Xr dwarf_add_AT_location_expr 3 , 118.Xr dwarf_add_expr_addr 3 , 119.Xr dwarf_add_expr_addr_b 3 , 120.Xr dwarf_expr_current_offset 3 , 121.Xr dwarf_expr_into_block 3 , 122.Xr dwarf_new_expr 3 123