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_add_expr_gen.3 3640 2018-10-14 14:09:13Z jkoshy $ 26.\" 27.Dd September 9, 2011 28.Dt DWARF_ADD_EXPR_GEN 3 29.Os 30.Sh NAME 31.Nm dwarf_add_expr_gen 32.Nd add an operator to a location expression descriptor 33.Sh LIBRARY 34.Lb libdwarf 35.Sh SYNOPSIS 36.In libdwarf.h 37.Ft "Dwarf_Unsigned" 38.Fo dwarf_add_expr_gen 39.Fa "Dwarf_P_Expr expr" 40.Fa "Dwarf_Small opcode" 41.Fa "Dwarf_Unsigned val1" 42.Fa "Dwarf_Unsigned val2" 43.Fa "Dwarf_Error *err" 44.Fc 45.Sh DESCRIPTION 46Function 47.Fn dwarf_add_expr_gen 48adds a location expression operator to the location expression 49descriptor referenced by argument 50.Ar expr . 51.Pp 52Argument 53.Ar expr 54should reference a location expression descriptor allocated using 55the function 56.Xr dwarf_new_expr 3 . 57.Pp 58Argument 59.Ar opcode 60specifies the operation code of the location expression operator. 61Valid values for this argument are those denoted by the 62.Dv DW_OP_ Ns * 63constants defined in 64.In libdwarf.h . 65.Pp 66To generate a 67.Dv DW_OP_addr 68operation, application code should instead use 69.Xr dwarf_add_expr_addr_b 3 . 70.Pp 71Argument 72.Ar val1 73specifies the first operand of the location expression operator. 74.Pp 75Argument 76.Ar val2 77specifies the second operand of the location expression operator. 78.Pp 79If argument 80.Ar err 81is not NULL, it will be used to store error information in case 82of an error. 83.Sh RETURN VALUES 84On success, function 85.Fn dwarf_add_expr_gen 86returns the size in bytes of the location expression byte stream 87generated. 88In case of an error, function 89.Fn dwarf_add_expr_gen 90returns 91.Dv DW_DLV_NOCOUNT 92and sets the argument 93.Ar err . 94.Sh ERRORS 95Function 96.Fn dwarf_add_expr_gen 97can fail with: 98.Bl -tag -width ".Bq Er DW_DLE_LOC_EXPR_BAD" 99.It Bq Er DW_DLE_ARGUMENT 100Argument 101.Ar expr 102was NULL. 103.It Bq Er DW_DLE_LOC_EXPR_BAD 104The operation code specified in argument 105.Ar opcode 106was invalid. 107.It Bq Er DW_DLE_MEMORY 108An out of memory condition was encountered during the execution of 109the function. 110.El 111.Sh SEE ALSO 112.Xr dwarf 3 , 113.Xr dwarf_add_AT_location_expr 3 , 114.Xr dwarf_add_expr_addr 3 , 115.Xr dwarf_add_expr_addr_b 3 , 116.Xr dwarf_expr_current_offset 3 , 117.Xr dwarf_expr_into_block 3 , 118.Xr dwarf_new_expr 3 119