1.\" $NetBSD: dwarf_expand_frame_instructions.3,v 1.4 2020/11/26 22:51:35 jkoshy 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 3644 2018-10-15 19:55:01Z jkoshy 28.\" 29.Dd November 9, 2011 30.Dt DWARF_EXPAND_FRAME_INSTRUCTIONS 3 31.Os 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 EXAMPLES 110To retrieve and expand the frame instructions for a given FDE 111descriptor, use: 112.Bd -literal -offset indent 113Dwarf_Dbg dbg; 114Dwarf_Cie cie; 115Dwarf_Fde fde; 116Dwarf_Ptr fde_inst; 117Dwarf_Unsigned fde_instlen; 118Dwarf_Frame_Op *ops; 119Dwarf_Signed opcnt; 120Dwarf_Error de; 121 122/* ... assuming `dbg` references a valid DWARF debugging context, 123 `fde` references a valid FDE descriptor and `cie` holds the CIE 124 descriptor associated with the FDE descriptor ... */ 125 126if (dwarf_get_fde_instr_bytes(fde, &fde_inst, &fde_instlen, 127 &de) != DW_DLV_OK) 128 errx(EXIT_FAILURE, "dwarf_get_fde_instr_bytes failed: %s", 129 dwarf_errmsg(de)); 130 131if (dwarf_expand_frame_instructions(cie, fde_inst, fde_instlen, 132 &ops, &opcnt, &de) != DW_DLV_OK) 133 errx(EXIT_FAILURE, 134 "dwarf_expand_frame_instructions failed: %s", 135 dwarf_errmsg(de)); 136 137for (i = 0; i < opcnt; i++) { 138 /* ... use ops[i] ... */ 139} 140 141/* Free the memory area when no longer needed. */ 142dwarf_dealloc(dbg, ops, DW_DLA_FRAME_BLOCK); 143.Ed 144.Sh ERRORS 145Function 146.Fn dwarf_expand_frame_instructions 147can fail with: 148.Bl -tag -width ".Bq Er DW_DLE_ARGUMENT" 149.It Bq Er DW_DLE_ARGUMENT 150One of the arguments 151.Ar cie , 152.Ar instructions , 153.Ar ret_ops 154or 155.Ar ret_opcnt 156was NULL. 157.It Bq Er DW_DLE_ARGUMENT 158Argument 159.Ar len 160was 0. 161.It Bq Er DW_DLE_MEMORY 162An out of memory condition was encountered during the execution of 163this function. 164.It Bq Er DW_DLE_FRAME_INSTR_EXEC_ERROR 165An unknown instruction was found in the instruction bytes provided 166in argument 167.Ar instructions . 168.El 169.Sh SEE ALSO 170.Xr dwarf 3 , 171.Xr dwarf_frame_instructions_dealloc 3 , 172.Xr dwarf_get_cie_index 3 , 173.Xr dwarf_get_cie_info 3 , 174.Xr dwarf_get_cie_of_fde 3 , 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