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

.\" Copyright (c) 2011 Kai Wang
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.\" $Id: dwarf_get_loclist_entry.3 3644 2018-10-15 19:55:01Z jkoshy $
.\"
.Dd July 6, 2011
.Dt DWARF_GET_LOCLIST_ENTRY 3
.Os
.Sh NAME
.Nm dwarf_get_loclist_entry
.Nd retrieve DWARF location list entry
.Sh LIBRARY
.Lb libdwarf
.Sh SYNOPSIS
.In libdwarf.h
.Ft int
.Fo dwarf_get_loclist_entry
.Fa "Dwarf_Debug dbg"
.Fa "Dwarf_Unsigned offset"
.Fa "Dwarf_Addr *hipc"
.Fa "Dwarf_Addr *lopc"
.Fa "Dwarf_Ptr *data"
.Fa "Dwarf_Unsigned *entry_len"
.Fa "Dwarf_Unsigned *next_entry"
.Fa "Dwarf_Error *err"
.Fc
.Sh DESCRIPTION
Function
.Fn dwarf_get_loclist_entry
retrieves a location list entry from the DWARF section
.Dq ".debug_loc" .
.Pp
Argument
.Ar dbg
should reference a DWARF debug context allocated using
.Xr dwarf_init 3 .
.Pp
Argument
.Ar offset
is an offset, relative to the
.Dq ".debug_loc"
section, to the start of the desired location list entry.
.Pp
Argument
.Ar hipc
should point to a location which will hold the offset, relative to the
base address of the location list entry, of the highest program
counter value for the entry.
.Pp
Argument
.Ar lowpc
should point to a location which will hold the offset, relative to the
base address of the location list entry, of the lowest program counter
value for the entry.
.Pp
Argument
.Ar data
should point to a location which will be set to a pointer to the location
list data.
.Pp
Argument
.Ar entry_len
should point to a location which will hold the length in bytes of the
location list data returned in argument
.Ar data .
.Pp
Argument
.Ar next_entry
should point to a location which will hold the offset of the next
location list entry.
.Pp
If argument
.Ar err
is not NULL, it will be used to store error information in case
of an error.
.Sh RETURN VALUES
Function
.Fn dwarf_get_loclist_entry
returns
.Dv DW_DLV_OK
when it succeeds.
It returns
.Dv DW_DLV_NO_ENTRY
if there is no location list 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 iterate through all the location list entries in the
.Dq ".debug_loc"
section, use:
.Bd -literal -offset indent
Dwarf_Debug dbg;
Dwarf_Unsigned off, len, next;
Dwarf_Addr hipc, lopc;
Dwarf_Ptr data;
Dwarf_Error de;
int ret;

off = 0;
while ((ret = dwarf_get_loclist_entry(dbg, off, &hipc, &lopc, &data,
    &len, &next, &de)) == DW_DLV_OK) {
	/* ... use loclist entry ... */
	off = next;
}
if (ret == DW_DLV_ERROR)
	warnx("dwarf_get_loclist_entry failed: %s", dwarf_errmsg(de));
.Ed
.Sh ERRORS
Function
.Fn dwarf_get_loclist_entry
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 hipc ,
.Ar lopc ,
.Ar data ,
.Ar entry_len
or
.Ar next_entry
was NULL.
.It Bq Er DW_DLE_NO_ENTRY
There is no location list at the specified offset
.Ar offset .
.El
.Sh SEE ALSO
.Xr dwarf 3 ,
.Xr dwarf_loclist 3 ,
.Xr dwarf_loclist_from_expr 3 ,
.Xr dwarf_loclist_from_expr_a 3 ,
.Xr dwarf_loclist_n 3