DWARF_PRODUCER_INIT(3) | Library Functions Manual | DWARF_PRODUCER_INIT(3)

# NAME

`dwarf_producer_init`, `dwarf_producer_init_b` — allocate a DWARF producer descriptor

# LIBRARY

DWARF Access Library (libdwarf, -ldwarf)

# SYNOPSIS

`#include <libdwarf.h>`

Dwarf_P_Debug
`dwarf_producer_init`(Dwarf_Unsigned flags, Dwarf_Callback_Func func, Dwarf_Handler errhand, Dwarf_Ptr errarg, Dwarf_Error *err);

Dwarf_P_Debug
`dwarf_producer_init_b`(Dwarf_Unsigned flags, Dwarf_Callback_Func_b func, Dwarf_Handler errhand, Dwarf_Ptr errarg, Dwarf_Error *error);

# DESCRIPTION

These functions allocate and return a Dwarf_P_Debug descriptor representing a DWARF producer instance.

The argument errhand should contain the address of a function to be called in case of an error. If this argument is `NULL`, the default error handling scheme is used, see dwarf(3).

The argument errarg will be passed to the error handler function when it is invoked.

The argument err references a memory location that would hold a Dwarf_Error descriptor in case of an error.

The argument flags specifies additional characteristics of the DWARF producer instance. The following flags are recognized:

`DW_DLC_ISA_IA64`
  (Deprecated) The target instruction set architecture is IA64. This flag is deprecated. Application code should use the dwarf_producer_set_isa(3) function to specify target instruction set architecture.
`DW_DLC_ISA_MIPS`
  (Deprecated) The target instruction set architecture is MIPS. This flag is deprecated. Application code should use the dwarf_producer_set_isa(3) function to specify target instruction set architecture.
`DW_DLC_SIZE_32`
  (Default) The target address size is 32-bit.
`DW_DLC_SIZE_64`
  The target address size is 64-bit.
`DW_DLC_STREAM_RELOCATIONS`
  (Default) Generate stream relocations.
`DW_DLC_SYMBOLIC_RELOCATIONS`
  Generate symbolic relocations.
`DW_DLC_TARGET_BIGENDIAN`
  The target is big endian.
`DW_DLC_TARGET_LITTLEENDIAN`
  The target is little endian.
`DW_DLC_WRITE`
  (Required) Permit writing of DWARF information.

The following flags are mutually exclusive.

- Flags `DW_DLC_ISA_IA64` and `DW_DLC_ISA_MIPS`.
- Flags `DW_DLC_SIZE_32` and `DW_DLC_SIZE_64`.
- Flags `DW_DLC_STREAM_RELOCATIONS` and `DW_DLC_SYMBOLIC_RELOCATIONS`.
- Flags `DW_DLC_TARGET_BIGENDIAN` and `DW_DLC_TARGET_LITTLEENDIAN`.

If neither of the flags `DW_DLC_TARGET_BIGENDIAN` and `DW_DLC_TARGET_LITTLEENDIAN` is set, the target's endianness is assumed to be the same as the host's endianness.

Argument func should point to an application-provided callback function of type Dwarf_Callback_Func_b. The type Dwarf_Callback_Func_b is defined in the header file `<libdwarf.h>` as:

    typedef int (*Dwarf_Callback_Func_b)(char *name, int size,
        Dwarf_Unsigned type, Dwarf_Unsigned flags, Dwarf_Unsigned link,
        Dwarf_Unsigned info, Dwarf_Unsigned *index, int *error);

This function is called by the DWARF Access Library (libdwarf, -ldwarf) once for each section in the object file that the library needs to create. The arguments to this callback function specify the values in the ELF section header for the section being created:

name
  The name of the section being created.
size
  The sh_size value in the section header.
type
  The sh_type value in the section header.
flags
  The sh_flags value in the section header.
link
  The sh_link value in the section header.
info
  The sh_info value in the section header.

On success, the callback function should return the section index value of the created section, and set the location pointed to by argument index to the symbol table index of the symbol that associated with the newly created section. This symbol table index will be used in relocation entries referring to the created section.

In case of failure, the callback function should return -1 and set the location pointed to by argument error to an application-defined error code. This application returned error code is currently ignored by the library.

Function `dwarf_producer_init`() is deprecated. Function `dwarf_producer_init`() is identical to function `dwarf_producer_init_b`() except that the callback function it expects can not properly handle arbitrary section symbol index values.

## Memory Management

The Dwarf_P_Debug instance returned by these functions should be freed using the function `dwarf_producer_finish`().

# RETURN VALUES

On success, these functions return the created DWARF producer descriptor. In case of an error, they return `DW_DLV_BADADDR` and set the argument err.

# EXAMPLES

To initialize a Dwarf_P_Debug instance for a MIPS32 big endian object, use:

    Dwarf_P_Debug dbg;
    Dwarf_Unsigned flags;
    Dwarf_Error de;

    /* ... assume cb_func points to the callback function ... */

    flags = DW_DLC_WRITE | DW_DLC_SIZE_32 | DW_DLC_ISA_MIPS |
        DW_DLC_STREAM_RELOCATIONS | DW_DLC_TARGET_BIGENDIAN;
    if ((dbg = dwarf_producer_init(flags, cb_func, NULL, NULL, &de)) ==
        DW_DLV_BADADDR)
    	warnx("dwarf_producer_init failed: %s", dwarf_errmsg(-1));

# ERRORS

These functions can fail with:

[`DW_DLE_ARGUMENT`]
  Argument func was `NULL`.
[`DW_DLE_ARGUMENT`]
  The flag `DW_DLC_WRITE` was not set in argument flags.
[`DW_DLE_ARGUMENT`]
  The flags `DW_DLC_SIZE_32` and `DW_DLC_SIZE_64` were both set in argument flags.
[`DW_DLE_ARGUMENT`]
  The flags `DW_DLC_ISA_IA64` and `DW_DLC_ISA_MIPS` were both set in argument flags.
[`DW_DLE_ARGUMENT`]
  The flags `DW_DLC_TARGET_BIGENDIAN` and `DW_DLC_TARGET_LITTLEENDIAN` were both set in argument flags.
[`DW_DLE_ARGUMENT`]
  The flags `DW_DLC_STREAM_RELOCATIONS` and `DW_DLC_SYMBOLIC_RELOCATIONS` were both set in argument flags.
[`DW_DLE_MEMORY`]
  An out of memory condition was encountered.

# SEE ALSO

dwarf(3), dwarf_errmsg(3), dwarf_producer_finish(3), dwarf_producer_set_isa(3), dwarf_transform_to_disk_form(3)

August 20, 2011 | NetBSD 11.0