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$Id: dwarf_init.3 3644 2018-10-15 19:55:01Z jkoshy $
.Dd November 9, 2011 .Dt DWARF_INIT 3 .Os .Sh NAME .Nm dwarf_init , .Nm dwarf_elf_init .Nd allocate a DWARF debug descriptor .Sh LIBRARY .Lb libdwarf .Sh SYNOPSIS n libdwarf.h .Ft int .Fo dwarf_init .Fa "int fd" .Fa "int mode" .Fa "Dwarf_Handler errhand" .Fa "Dwarf_Ptr errarg" .Fa "Dwarf_Debug *ret" .Fa "Dwarf_Error *err" .Fc .Ft in .Fo dwarf_elf_init .Fa "Elf *elf" .Fa "int mode" .Fa "Dwarf_Handler errhand" .Fa "Dwarf_Ptr errarg" .Fa "Dwarf_Debug *ret" .Fa "Dwarf_Error *err" .Fc .Sh DESCRIPTION These functions allocate and return a .Vt Dwarf_Debug instance for the object denoted by argument .Ar fd or .Ar elf . This instance would be used for subsequent access to debugging information in the object by other functions in the DWARF(3) library.
p For function .Fn dwarf_init , argument .Ar fd denotes an open file descriptor referencing a compilation object. Function .Fn dwarf_init implicitly allocates an .Vt Elf descriptor for argument .Ar fd .
p For function .Fn dwarf_elf_init , argument .Ar elf denotes a descriptor returned by .Xr elf_begin 3 or .Xr elf_memory 3 .
p Argument .Ar mode specifies the access mode desired. It should be at least as permissive as the mode with which the file descriptor .Ar fd or the ELF descriptor .Ar elf was created with. Legal values for argument .Ar mode are:
p l -tag -width "DW_DLC_WRITE" -compact t DW_DLC_RDWR Permit reading and writing of DWARF information. t DW_DLC_READ Operate in read-only mode. t DW_DLC_WRITE Permit writing of DWARF information. .El
p Argument .Ar errhand denotes a function to be called in case of an error. If this argument is .Dv NULL then a default error handling scheme is used. See .Xr dwarf 3 for a description of the error handling scheme used by the DWARF(3) library.
p Argument .Ar errarg is passed to the error handler function denoted by argument .Ar errhand when it is invoked.
p Argument .Ar ret points to the memory location that will hold a .Vt Dwarf_Debug reference on a successful call these functions.
p Argument .Ar err references a memory location that would hold a .Vt Dwarf_Error descriptor in case of an error. .Ss Memory Management The .Vt Dwarf_Debug instance returned by these functions should be freed using .Fn dwarf_finish . .Sh IMPLEMENTATION NOTES The current implementation does not support access modes .Dv DW_DLC_RDWR and .Dv DW_DLC_WRITE . .Sh RETURN VALUES These functions return the following values: l -tag -width ".Bq Er DW_DLV_NO_ENTRY" t Bq Er DW_DLV_OK This return value indicates a successful return. t Bq Er DW_DLV_ERROR The operation failed. t Bq Er DW_DLV_NO_ENTRY The object specified by arguments .Ar "fd" or .Ar "elf" did not contain debug information. .El .Sh EXAMPLES To initialize a .Vt Dwarf_Debug instance from a open file descriptor referencing an ELF object, and with the default error handler, use: d -literal -offset indent 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)); .Ed .Sh SEE ALSO .Xr dwarf 3 , .Xr dwarf_errmsg 3 , .Xr dwarf_finish 3 , .Xr dwarf_get_elf 3 , .Xr elf_begin 3 , .Xr elf_memory 3