1.\" $NetBSD: dwarf_expand_frame_instructions.3,v 1.2 2014/03/09 16:58:03 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_expand_frame_instructions.3 2122 2011-11-09 15:35:14Z jkoshy 28.\" 29.Dd November 9, 2011 30.Os 31.Dt DWARF_EXPAND_FRAME_INSTRUCTIONS 3 32.Sh NAME 33.Nm dwarf_expand_frame_instructions 34.Nd expand frame instructions 35.Sh LIBRARY 36.Lb libdwarf 37.Sh SYNOPSIS 38.In libdwarf.h 39.Ft int 40.Fo dwarf_expand_frame_instructions 41.Fa "Dwarf_Cie cie" 42.Fa "Dwarf_Ptr instructions" 43.Fa "Dwarf_Unsigned len" 44.Fa "Dwarf_Frame_Op **ret_ops" 45.Fa "Dwarf_Signed *ret_opcnt" 46.Fa "Dwarf_Error *error" 47.Fc 48.Sh DESCRIPTION 49Function 50.Fn dwarf_expand_frame_instructions 51translates DWARF frame instruction bytes into an array of 52.Vt Dwarf_Frame_Op 53descriptors. 54.Pp 55Argument 56.Ar cie 57should reference the CIE descriptor associated with the instructions 58to be translated. 59.Pp 60Arugment 61.Ar instructions 62should point to an array of frame instruction bytes, as 63returned by the functions 64.Xr dwarf_get_cie_info 3 65or 66.Xr dwarf_get_fde_instr_bytes 3 . 67.Pp 68Argument 69.Ar len 70should specify the number of the frame instruction bytes to be 71translated. 72.Pp 73Argument 74.Ar ret_ops 75should point to a location that will be set to a pointer to 76an array of translated 77.Vt Dwarf_Frame_Op 78descriptors. 79.Pp 80Argument 81.Ar ret_opcnt 82should point to a location that will hold the total number of the 83returned descriptors. 84.Pp 85If argument 86.Ar err 87is not NULL, it will be used to store error information in case of an 88error. 89.Ss Memory Management 90The memory area used for the descriptor array returned in argument 91.Ar ret_ops 92is allocated by 93.Lb libdwarf . 94Application code should use function 95.Xr dwarf_dealloc 3 96with type 97.Dv DW_DLA_FRAME_BLOCK 98to free the memory area when the descriptor array is no longer needed. 99.Sh RETURN VALUES 100Function 101.Fn dwarf_expand_frame_instructions 102returns 103.Dv DW_DLV_OK 104when it succeeds. 105In case of an error, it returns 106.Dv DW_DLV_ERROR 107and sets the argument 108.Ar err . 109.Sh ERRORS 110Function 111.Fn dwarf_expand_frame_instructions 112can fail with: 113.Bl -tag -width ".Bq Er DW_DLE_ARGUMENT" 114.It Bq Er DW_DLE_ARGUMENT 115One of the arguments 116.Ar cie , 117.Ar instructions , 118.Ar ret_ops 119or 120.Ar ret_opcnt 121was NULL. 122.It Bq Er DW_DLE_ARGUMENT 123Argument 124.Ar len 125was 0. 126.It Bq Er DW_DLE_MEMORY 127An out of memory condition was encountered during the execution of 128this function. 129.It Bq Er DW_DLE_FRAME_INSTR_EXEC_ERROR 130An unknown instruction was found in the instruction bytes provided 131in argument 132.Ar instructions . 133.El 134.Sh EXAMPLE 135To retrieve and expand the frame instructions for a given FDE 136descriptor, use: 137.Bd -literal -offset indent 138Dwarf_Dbg dbg; 139Dwarf_Cie cie; 140Dwarf_Fde fde; 141Dwarf_Ptr fde_inst; 142Dwarf_Unsigned fde_instlen; 143Dwarf_Frame_Op *ops; 144Dwarf_Signed opcnt; 145Dwarf_Error de; 146 147/* ... assuming `dbg` references a valid DWARF debugging context, 148 `fde` references a valid FDE descriptor and `cie` holds the CIE 149 descriptor associated with the FDE descriptor ... */ 150 151if (dwarf_get_fde_instr_bytes(fde, &fde_inst, &fde_instlen, 152 &de) != DW_DLV_OK) 153 errx(EXIT_FAILURE, "dwarf_get_fde_instr_bytes failed: %s", 154 dwarf_errmsg(de)); 155 156if (dwarf_expand_frame_instructions(cie, fde_inst, fde_instlen, 157 &ops, &opcnt, &de) != DW_DLV_OK) 158 errx(EXIT_FAILURE, 159 "dwarf_expand_frame_instructions failed: %s", 160 dwarf_errmsg(de)); 161 162for (i = 0; i < opcnt; i++) { 163 /* ... use ops[i] ... */ 164} 165 166/* Free the memory area when no longer needed. */ 167dwarf_dealloc(dbg, ops, DW_DLA_FRAME_BLOCK); 168.Ed 169.Sh SEE ALSO 170.Xr dwarf 3 , 171.Xr dwarf_frame_instructions_dealloc 3 , 172.Xr dwarf_get_cie_info 3 , 173.Xr dwarf_get_cie_index 3 , 174.Xr dwarf_get_cie_of_fde , 175.Xr dwarf_get_fde_at_pc 3 , 176.Xr dwarf_get_fde_info_for_all_regs 3 , 177.Xr dwarf_get_fde_info_for_all_regs3 3 , 178.Xr dwarf_get_fde_info_for_cfa_reg3 3 , 179.Xr dwarf_get_fde_info_for_reg 3 , 180.Xr dwarf_get_fde_info_for_reg3 3 , 181.Xr dwarf_get_fde_instr_bytes 3 , 182.Xr dwarf_get_fde_list 3 , 183.Xr dwarf_get_fde_list_eh 3 , 184.Xr dwarf_get_fde_n 3 185