xref: /freebsd/contrib/elftoolchain/libdwarf/dwarf_get_macro_details.3 (revision ae500c1ff8974130f7f2692772cf288b90349e0d)

.\" Copyright (c) 2011 Kai Wang
.\" All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.\" $Id: dwarf_get_macro_details.3 3644 2018-10-15 19:55:01Z jkoshy $
.\"
.Dd March 20, 2011
.Dt DWARF_GET_MACRO_DETAILS 3
.Os
.Sh NAME
.Nm dwarf_get_macro_details
.Nd retrieve macro information
.Sh LIBRARY
.Lb libdwarf
.Sh SYNOPSIS
.In libdwarf.h
.Ft int
.Fo dwarf_get_macro_details
.Fa "Dwarf_Debug dbg"
.Fa "Dwarf_Off offset"
.Fa "Dwarf_Unsigned max_count"
.Fa "Dwarf_Signed *entry_cnt"
.Fa "Dwarf_Macro_Details **details"
.Fa "Dwarf_Error *err"
.Fc
.Sh DESCRIPTION
Function
.Fn dwarf_get_macro_details
retrieves information about macros associated with a DWARF debug
context.
Information about macro entries are returned as an array of
descriptors of type
.Vt Dwarf_Macro_Details ,
with each
.Vt Dwarf_Macro_Details
descriptor describing one macro information entry.
.Pp
Argument
.Ar dbg
should reference a DWARF debug context allocated using
.Xr dwarf_init 3 .
Argument
.Ar offset
is an offset, relative to the
.Dq ".debug_macinfo"
section, to the start of the desired macro information.
Argument
.Ar max_count
specifies the maximum number of macro information entries
to be returned, or 0 if all entries are to be returned.
Argument
.Ar entry_cnt
should point to a location that will be set to the number
of entries actually returned.
Argument
.Ar details
should point to a location that will be set to a pointer to
an array of
.Vt Dwarf_Macro_Details
descriptors.
If argument
.Ar err
is not NULL, it will be used to store error information in case
of an error.
.Pp
.Vt Dwarf_Macro_Details
descriptors are defined in the header file
.In libdwarf.h ,
and consist of the following fields:
.Bl -tag -width ".Va dmd_fileindex" -compact
.It Va dmd_offset
The section-relative offset within the
.Dq ".debug_macinfo"
section of the macro information entry being described.
.It Va dmd_type
The type code of this macro information entry; one of the
.Dv DW_MACINFO_*
constants defined by the DWARF specification.
.It Va dmd_lineno
The line number associated with the macro information
entry, or 0 if there is no applicable line number.
.It Va dmd_fileindex
The source file index for the macro information entry.
This field is only meaningful when
.Va dmd_type
field is set to
.Dv DW_MACINFO_start_file .
.It Va dmd_macro
The contents of this field is a pointer to a NUL-terminated string
whose meaning depends on the value of the
.Va dmd_type
field:
.Bl -tag -width ".Dv DW_MACINFO_vendor_ext" -compact
.It Dv DW_MACINFO_define
The returned string contains the macro name and value.
.It Dv DW_MACINFO_undef
The string holds the macro name.
.It Dv DW_MACINFO_vendor_ext
The
.Va dmd_macro
field points to a vendor defined string.
.El
The field is NULL for other values of
.Va dmd_type .
.El
.Ss Memory Management
The memory area used for the array of
.Vt Dwarf_Macro_Details
descriptors returned in argument
.Ar details
is owned by the
.Lb libdwarf .
The application should not attempt to directly free this pointer.
Portable code should instead use
.Fn dwarf_dealloc
with the allocation type
.Dv DW_DLA_STRING
to indicate that the memory may be freed.
.Sh RETURN VALUES
Function
.Fn dwarf_get_macro_details
returns
.Dv DW_DLV_OK
when it succeeds.
It returns
.Dv DW_DLV_NO_ENTRY
if there is no more macro information at the specified offset
.Ar offset .
In case of an error, it returns
.Dv DW_DLV_ERROR
and sets the argument
.Ar err .
.Sh EXAMPLES
To loop through all the macro information entries associated with
a DWARF debug context:
.Bd -literal -offset indent
Dwarf_Debug dbg;
Dwarf_Unsigned offset;
Dwarf_Signed cnt;
Dwarf_Macro_Details *md;
Dwarf_Error de;

offset = 0;
while (dwarf_get_macro_details(dbg, offset, 0,
    &cnt, &md, &de) == DW_DLV_OK) {
	for (i = 0; i < cnt; i++) {
		/* Access fields of md[i] ... */
	}
	offset = md[cnt - 1].dmd_offset + 1;
}
.Ed
.Sh ERRORS
Function
.Fn dwarf_get_macro_details
can fail with:
.Bl -tag -width ".Bq Er DW_DLE_NO_ENTRY"
.It Bq Er DW_DLE_ARGUMENT
One of the arguments
.Ar dbg ,
.Ar entry_cnt
or
.Ar details
was NULL.
.It Bq Er DW_DLE_NO_ENTRY
There is no more macro information at the specified offset
.Ar offset .
.El
.Sh SEE ALSO
.Xr dwarf 3 ,
.Xr dwarf_dealloc 3 ,
.Xr dwarf_find_macro_value_start 3 ,
.Xr dwarf_init 3