NAME
dwarf_init
,
dwarf_elf_init
—
allocate a DWARF debug
descriptor
LIBRARY
library “libdwarf”
SYNOPSIS
#include
<libdwarf.h>
int
dwarf_init
(int fd,
int mode, Dwarf_Handler errhand,
Dwarf_Ptr errarg, Dwarf_Debug
*ret, Dwarf_Error *err);
in
dwarf_elf_init
(Elf *elf,
int mode, Dwarf_Handler errhand,
Dwarf_Ptr errarg, Dwarf_Debug
*ret, Dwarf_Error *err);
DESCRIPTION
These functions allocate and return a Dwarf_Debug instance for the object denoted by argument fd or elf. This instance would be used for subsequent access to debugging information in the object by other functions in the DWARF(3) library.For function
dwarf_init
(),
argument fd denotes an open file descriptor
referencing a compilation object. Function
dwarf_init
() implicitly allocates an
Elf descriptor for argument
fd.
For function
dwarf_elf_init
(),
argument elf denotes a descriptor returned by
elf_begin(3) or
elf_memory(3).
Argument mode specifies the access mode desired. It should be at least as permissive as the mode with which the file descriptor fd or the ELF descriptor elf was created with. Legal values for argument mode are:
- DW_DLC_RDWR
- Permit reading and writing of DWARF information.
- DW_DLC_READ
- Operate in read-only mode.
- DW_DLC_WRITE
- Permit writing of DWARF information.
Argument errhand denotes a function to be
called in case of an error. If this argument is NULL
then a default error handling scheme is used. See
dwarf(3) for a description of the error handling scheme used by the
DWARF(3) library.
Argument errarg is passed to the error handler function denoted by argument errhand when it is invoked.
Argument ret points to the memory location that will hold a Dwarf_Debug reference on a successful call these functions.
Argument err references a memory location that would hold a Dwarf_Error descriptor in case of an error.
Memory Management
The Dwarf_Debug instance returned by these
functions should be freed using
dwarf_finish
().
IMPLEMENTATION NOTES
The current implementation does not support access modes
DW_DLC_RDWR
and
DW_DLC_WRITE
.
RETURN VALUES
These functions return the following values:
- [
DW_DLV_OK
] - This return value indicates a successful return.
- [
DW_DLV_ERROR
] - The operation failed.
- [
DW_DLV_NO_ENTRY
] - The object specified by arguments fd or elf did not contain debug information.
EXAMPLES
To initialize a Dwarf_Debug instance from a open file descriptor referencing an ELF object, and with the default error handler, use:
Dwarf_Error err; Dwarf_Debug dbg; if (dwarf_init(fd, DW_DLC_READ, NULL, NULL, &dbg, &err) != DW_DLV_OK) errx(EXIT_FAILURE, "dwarf_init: %s", dwarf_errmsg(err));
SEE ALSO
dwarf(3), dwarf_errmsg(3), dwarf_finish(3), dwarf_get_elf(3), elf_begin(3), elf_memory(3)