180 lines
4.9 KiB
Groff
180 lines
4.9 KiB
Groff
.\" Copyright (c) 2011 Kai Wang
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" $Id: dwarf_get_abbrev.3 2071 2011-10-27 03:20:00Z jkoshy $
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.\"
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.Dd March 27, 2011
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.Os
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.Dt DWARF_GET_ABBREV 3
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.Sh NAME
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.Nm dwarf_get_abbrev
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.Nd retrieve abbreviation information
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.Sh LIBRARY
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.Lb libdwarf
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.Sh SYNOPSIS
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.In libdwarf.h
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.Ft int
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.Fo dwarf_get_abbrev
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.Fa "Dwarf_Debug dbg"
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.Fa "Dwarf_Unsigned offset"
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.Fa "Dwarf_Abbrev *ret_abbrev"
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.Fa "Dwarf_Unsigned *length"
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.Fa "Dwarf_Unsigned *attr_count"
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.Fa "Dwarf_Error *err"
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.Fc
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.Sh DESCRIPTION
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Function
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.Fn dwarf_get_abbrev
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retrieves information about an abbreviation from the DWARF abbreviations
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section,
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.Dq ".debug_abbrev" .
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Abbreviation information is returned using an opaque descriptor
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of type
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.Vt Dwarf_Abbrev .
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The returned
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.Vt Dwarf_Abbrev
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descriptor may then be passed to the other abbreviation related APIs
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in the DWARF(3) API to retrieve specific information about the
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abbreviation.
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.Pp
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Argument
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.Ar dbg
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should reference a DWARF debug context allocated using
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.Xr dwarf_init 3 .
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.Pp
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Argument
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.Ar offset
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should be an offset, relative to the
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.Dq ".debug_abbrev"
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section, to the start of an abbreviation entry.
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.Pp
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Argument
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.Ar ret_abbrev
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should point to a location that will hold a pointer to the
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returned
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.Vt Dwarf_Abbrev
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descriptor.
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.Pp
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Argument
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.Ar length
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should point to a location that will hold the number of bytes used
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by the abbrevation in the DWARF
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.Dq ".debug_abbrev"
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section.
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.Pp
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Argument
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.Ar attr_count
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should point to a location that will hold the number of
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attributes in the abbrevation.
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.Pp
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If argument
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.Ar err
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is not NULL, it will be used to store error information in case of an
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error.
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.Ss Memory Management
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The memory area used for the
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.Vt Dwarf_Abbrev
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descriptor returned in argument
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.Ar ret_abbrev
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is allocated by the
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.Lb libdwarf .
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Application code should use function
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.Fn dwarf_dealloc
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with the allocation type
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.Dv DW_DLA_ABBREV
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to free the memory area when the
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.Vt Dwarf_Abbrev
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descriptor is no longer needed.
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.Ss Application Programming Notes
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The last abbreviation entry in a standard DWARF abbreviation section
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will have a special length value of 1.
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.Sh RETURN VALUES
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Function
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.Fn dwarf_get_abbrev
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returns
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.Dv DW_DLV_OK
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when it succeeds.
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It returns
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.Dv DW_DLV_NO_ENTRY
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if there is no abbreviation information at offset
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.Ar offset .
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In case of an error, it returns
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.Dv DW_DLV_ERROR
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and sets the argument
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.Ar err .
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.Sh ERRORS
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Function
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.Fn dwarf_get_abbrev
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can fail with:
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.Bl -tag -width ".Bq Er DW_DLE_NO_ENTRY"
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.It Bq Er DW_DLE_ARGUMENT
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One of the arguments
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.Ar dbg ,
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.Ar ret_abbrev ,
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.Ar length
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or
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.Ar attr_count
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was NULL.
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.It Bq Er DW_DLE_NO_ENTRY
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There is no abbreviation information at offset
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.Ar offset .
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.El
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.Sh EXAMPLE
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To loop through all the abbreviation information associated with
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a DWARF debug context, use:
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.Bd -literal -offset indent
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Dwarf_Debug dbg;
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Dwarf_Abbrev ab;
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Dwarf_Off aboff;
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Dwarf_Unsigned length, attr_count;
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Dwarf_Half tag;
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Dwarf_Error de;
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int ret;
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while ((ret = dwarf_next_cu_header(dbg, NULL, NULL, &aboff,
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NULL, NULL, &de)) == DW_DLV_OK) {
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while ((ret = dwarf_get_abbrev(re->dbg, aboff, &ab, &length,
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&attr_count, &de)) == DW_DLV_OK) {
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if (length == 1) /* Last entry. */
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break;
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aboff += length;
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if (dwarf_get_abbrev_tag(ab, &tag, &de) != DW_DLV_OK) {
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warnx("dwarf_get_abbrev_tag failed: %s",
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dwarf_errmsg(de));
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continue;
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}
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if (ret != DW_DLV_OK)
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warnx("dwarf_get_abbrev: %s", dwarf_errmsg(de));
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}
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if (ret == DW_DLV_ERROR)
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warnx("dwarf_next_cu_header: %s", dwarf_errmsg(de));
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.Ed
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.Sh SEE ALSO
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.Xr dwarf 3 ,
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.Xr dwarf_dealloc 3 ,
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.Xr dwarf_get_abbrev_tag 3 ,
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.Xr dwarf_get_abbrev_code 3 ,
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.Xr dwarf_get_abbrev_children_flag 3 ,
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.Xr dwarf_get_abbrev_entry 3
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