freebsd-skq/contrib/elftoolchain/libdwarf/dwarf_expand_frame_instructions.3
Ed Maste b00fe64f4a Update to ELF Tool Chain r3197
Highlights:
 - Fix man page markup, whitespace, and typos
 - Fix sh_info of SHT_GROUP section to point to the correct string
 - Improve validation in readelf and elfcopy/strip
 - Handle DWARF 4's DW_AT_high_pc in addr2line

Sponsored by:	The FreeBSD Foundation
2015-05-14 19:48:15 +00:00

183 lines
5.1 KiB
Groff

.\" Copyright (c) 2011 Kai Wang
.\" All rights reserved.
.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" $Id: dwarf_expand_frame_instructions.3 3181 2015-04-10 13:22:51Z emaste $
.\"
.Dd November 9, 2011
.Os
.Dt DWARF_EXPAND_FRAME_INSTRUCTIONS 3
.Sh NAME
.Nm dwarf_expand_frame_instructions
.Nd expand frame instructions
.Sh LIBRARY
.Lb libdwarf
.Sh SYNOPSIS
.In libdwarf.h
.Ft int
.Fo dwarf_expand_frame_instructions
.Fa "Dwarf_Cie cie"
.Fa "Dwarf_Ptr instructions"
.Fa "Dwarf_Unsigned len"
.Fa "Dwarf_Frame_Op **ret_ops"
.Fa "Dwarf_Signed *ret_opcnt"
.Fa "Dwarf_Error *error"
.Fc
.Sh DESCRIPTION
Function
.Fn dwarf_expand_frame_instructions
translates DWARF frame instruction bytes into an array of
.Vt Dwarf_Frame_Op
descriptors.
.Pp
Argument
.Ar cie
should reference the CIE descriptor associated with the instructions
to be translated.
.Pp
Arugment
.Ar instructions
should point to an array of frame instruction bytes, as
returned by the functions
.Xr dwarf_get_cie_info 3
or
.Xr dwarf_get_fde_instr_bytes 3 .
.Pp
Argument
.Ar len
should specify the number of the frame instruction bytes to be
translated.
.Pp
Argument
.Ar ret_ops
should point to a location that will be set to a pointer to
an array of translated
.Vt Dwarf_Frame_Op
descriptors.
.Pp
Argument
.Ar ret_opcnt
should point to a location that will hold the total number of the
returned descriptors.
.Pp
If argument
.Ar err
is not NULL, it will be used to store error information in case of an
error.
.Ss Memory Management
The memory area used for the descriptor array returned in argument
.Ar ret_ops
is allocated by
.Lb libdwarf .
Application code should use function
.Xr dwarf_dealloc 3
with type
.Dv DW_DLA_FRAME_BLOCK
to free the memory area when the descriptor array is no longer needed.
.Sh RETURN VALUES
Function
.Fn dwarf_expand_frame_instructions
returns
.Dv DW_DLV_OK
when it succeeds.
In case of an error, it returns
.Dv DW_DLV_ERROR
and sets the argument
.Ar err .
.Sh ERRORS
Function
.Fn dwarf_expand_frame_instructions
can fail with:
.Bl -tag -width ".Bq Er DW_DLE_ARGUMENT"
.It Bq Er DW_DLE_ARGUMENT
One of the arguments
.Ar cie ,
.Ar instructions ,
.Ar ret_ops
or
.Ar ret_opcnt
was NULL.
.It Bq Er DW_DLE_ARGUMENT
Argument
.Ar len
was 0.
.It Bq Er DW_DLE_MEMORY
An out of memory condition was encountered during the execution of
this function.
.It Bq Er DW_DLE_FRAME_INSTR_EXEC_ERROR
An unknown instruction was found in the instruction bytes provided
in argument
.Ar instructions .
.El
.Sh EXAMPLE
To retrieve and expand the frame instructions for a given FDE
descriptor, use:
.Bd -literal -offset indent
Dwarf_Dbg dbg;
Dwarf_Cie cie;
Dwarf_Fde fde;
Dwarf_Ptr fde_inst;
Dwarf_Unsigned fde_instlen;
Dwarf_Frame_Op *ops;
Dwarf_Signed opcnt;
Dwarf_Error de;
/* ... assuming `dbg` references a valid DWARF debugging context,
`fde` references a valid FDE descriptor and `cie` holds the CIE
descriptor associated with the FDE descriptor ... */
if (dwarf_get_fde_instr_bytes(fde, &fde_inst, &fde_instlen,
&de) != DW_DLV_OK)
errx(EXIT_FAILURE, "dwarf_get_fde_instr_bytes failed: %s",
dwarf_errmsg(de));
if (dwarf_expand_frame_instructions(cie, fde_inst, fde_instlen,
&ops, &opcnt, &de) != DW_DLV_OK)
errx(EXIT_FAILURE,
"dwarf_expand_frame_instructions failed: %s",
dwarf_errmsg(de));
for (i = 0; i < opcnt; i++) {
/* ... use ops[i] ... */
}
/* Free the memory area when no longer needed. */
dwarf_dealloc(dbg, ops, DW_DLA_FRAME_BLOCK);
.Ed
.Sh SEE ALSO
.Xr dwarf 3 ,
.Xr dwarf_frame_instructions_dealloc 3 ,
.Xr dwarf_get_cie_info 3 ,
.Xr dwarf_get_cie_index 3 ,
.Xr dwarf_get_cie_of_fde ,
.Xr dwarf_get_fde_at_pc 3 ,
.Xr dwarf_get_fde_info_for_all_regs 3 ,
.Xr dwarf_get_fde_info_for_all_regs3 3 ,
.Xr dwarf_get_fde_info_for_cfa_reg3 3 ,
.Xr dwarf_get_fde_info_for_reg 3 ,
.Xr dwarf_get_fde_info_for_reg3 3 ,
.Xr dwarf_get_fde_instr_bytes 3 ,
.Xr dwarf_get_fde_list 3 ,
.Xr dwarf_get_fde_list_eh 3 ,
.Xr dwarf_get_fde_n 3