xref: /freebsd-src/contrib/elftoolchain/libdwarf/dwarf_get_str.3 (revision ae500c1ff8974130f7f2692772cf288b90349e0d)

.\" Copyright (c) 2011 Kai Wang
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.\" $Id: dwarf_get_str.3 3644 2018-10-15 19:55:01Z jkoshy $
.\"
.Dd April 3, 2011
.Dt DWARF_GET_STR 3
.Os
.Sh NAME
.Nm dwarf_get_str
.Nd retrieve a string from the DWARF string section
.Sh LIBRARY
.Lb libdwarf
.Sh SYNOPSIS
.In libdwarf.h
.Ft int
.Fo dwarf_get_str
.Fa "Dwarf_Debug dbg"
.Fa "Dwarf_Off offset"
.Fa "char **string"
.Fa "Dwarf_Signed *len"
.Fa "Dwarf_Error *err"
.Fc
.Sh DESCRIPTION
Function
.Fn dwarf_get_str
retrieves a NUL-terminated string from the DWARF string section
.Dq ".debug_str" .
.Pp
Argument
.Ar dbg
should reference a DWARF debug context allocated using
.Xr dwarf_init 3 .
.Pp
Argument
.Ar offset
should be an offset, relative to the
.Dq ".debug_str"
section, specifying the start of the desired string.
.Pp
Argument
.Ar string
should point to a location which will hold a returned
pointer to a NUL-terminated string.
.Pp
Argument
.Ar len
should point to a location which will hold the length
of the returned string.
The returned length does not include the space needed for
the NUL-terminator.
.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_str
returns
.Dv DW_DLV_OK
when it succeeds.
It returns
.Dv DW_DLV_NO_ENTRY
if there is no
.Dq ".debug_str"
section associated with the specified debugging context,
or if the provided offset
.Ar offset
is at the very end of
.Dq ".debug_str"
section.
In case of an error, it returns
.Dv DW_DLV_ERROR
and sets the argument
.Ar err .
.Sh EXAMPLES
To retrieve all the strings in the DWARF string section, use:
.Bd -literal -offset indent
Dwarf_Debug dbg;
Dwarf_Off offset;
Dwarf_Signed len;
Dwarf_Error de;
char *str;
int ret

offset = 0;
while ((ret = dwarf_get_str(dbg, offset, &str, &len, &de)) ==
	DW_DLV_OK) {
	/* .. Use the retrieved string. .. */
	offset += len + 1; /* Account for the terminating NUL. */
}

if (ret == DW_DLV_ERROR)
	warnx("dwarf_get_str: %s", dwarf_errmsg(de));
.Ed
.Sh ERRORS
Function
.Fn dwarf_get_str
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 string
or
.Ar len
was NULL.
.It Bq Er DW_DLE_ARGUMENT
Argument
.Ar offset
was out of range.
.It Bq Er DW_DLE_NO_ENTRY
The debugging context
.Ar dbg
did not contain a
.Dq ".debug_str"
string section.
.It Bq Er DW_DLE_NO_ENTRY
Argument
.Ar offset
was at the very end of the
.Dq ".debug_str"
section.
.El
.Sh SEE ALSO
.Xr dwarf 3 ,
.Xr dwarf_init 3