dwarf_new_expr(3) [freebsd man page]

DWARF_NEW_EXPR(3)					   BSD Library Functions Manual 					 DWARF_NEW_EXPR(3)

NAME

     dwarf_new_expr -- create a location expression descriptor

LIBRARY

     DWARF Access Library (libdwarf, -ldwarf)

SYNOPSIS

     #include <libdwarf.h>

     Dwarf_P_Expr
     dwarf_new_expr(Dwarf_P_Debug dbg, Dwarf_Error *err);

DESCRIPTION

     Function dwarf_new_expr() allocates a DWARF location expression descriptor used to build up a location expression stream.

     The application can use the functions dwarf_add_expr_gen(3) and dwarf_add_expr_addr_b(3) to add location expression operators to the created
     descriptor.  When done, the application can call the function dwarf_expr_into_block(3) to retrieve the generated byte stream for the location
     expression, or call the function dwarf_add_AT_location_expr(3) to create an attribute with the location expression stream as its value.

     Argument dbg should reference a DWARF producer instance allocated using dwarf_producer_init(3) or dwarf_producer_init_b(3).

     If argument err is not NULL, it will be used to store error information in case of an error.

RETURN VALUES

     On success, function dwarf_new_expr() returns the created location expression descriptor.	In case of an error, function dwarf_new_expr()
     returns DW_DLV_BADADDR and sets the argument err.

ERRORS

     Function dwarf_new_expr() can fail with:

     [DW_DLE_ARGUMENT]	Argument dbg was NULL.

     [DW_DLE_MEMORY]	An out of memory condition was encountered during the execution of the function.

EXAMPLES

     To create a location expression descriptor, add location expression operators to it and to retrieve the generated byte stream, use:

	   Dwarf_P_Debug dbg;
	   Dwarf_Error de;
	   Dwarf_P_Expr pe;
	   Dwarf_Addr buf;
	   Dwarf_Unsigned len;

	   /* ...Assume that `dbg' refers to a DWARF producer instance... */

	   if ((pe = dwarf_new_expr(dbg, &de)) == DW_DLV_BADADDR) {
		   warnx("dwarf_new_expr failed: %s", dwarf_errmsg(-1));
		   return;
	   }

	   if (dwarf_add_expr_gen(pe, DW_OP_regx, 55, 0, &de) ==
	       DW_DLV_NOCOUNT) {
		   warnx("dwarf_add_expr_gen failed: %s", dwarf_errmsg(-1));
		   return;
	   }

	   if ((buf = dwarf_expr_into_block(pe, &len, &de)) ==
	       DW_DLV_BADADDR) {
		   warnx("dwarf_expr_into_block failed: %s",
		       dwarf_errmsg(-1));
		   return;
	   }

SEE ALSO

     dwarf(3), dwarf_add_AT_location_expr(3), dwarf_add_expr_gen(3), dwarf_add_expr_addr(3), dwarf_add_expr_addr_b(3),
     dwarf_expr_current_offset(3), dwarf_expr_into_block(3), dwarf_producer_init(3), dwarf_producer_init_b(3)

BSD
								 September 8, 2011							       BSD

DWARF_GET_SECTION_BYTES(3)				   BSD Library Functions Manual 				DWARF_GET_SECTION_BYTES(3)

NAME

     dwarf_get_section_bytes -- retrieve ELF section byte streams

LIBRARY

     DWARF Access Library (libdwarf, -ldwarf)

SYNOPSIS

     #include <libdwarf.h>

     Dwarf_Ptr
     dwarf_get_section_bytes(Dwarf_P_Debug dbg, Dwarf_Signed dwarf_section, Dwarf_Signed *elf_section_index, Dwarf_Unsigned *length,
	 Dwarf_Error *err);

DESCRIPTION

     Function dwarf_get_section_bytes() returns the ELF section byte streams generated by a prior call to function
     dwarf_transform_to_disk_form(3).

     Each call to function dwarf_get_section_bytes() will return the byte stream for one ELF section.  The first call to this function will always
     return the first ELF section, and the subsequent calls will return the rest of sections in the order when they were generated, until the last
     one.  The total number of sections generated is returned by the function dwarf_transform_to_disk_form(3).

     Argument dbg should reference a DWARF producer instance allocated using the functions dwarf_producer_init(3) or dwarf_producer_init_b(3).

     Argument dwarf_section is currently ignored.

     Argument elf_section_index should point to a location which will be set to the section index value of the returned ELF section.

     Argument length should point to a location which will hold the length in bytes of the returned ELF section.

     If argument err is not NULL, it will be used to store error information in case of an error.

   Memory Management
     The memory areas used for the returned ELF section byte streams should be freed using the function dwarf_producer_finish().

RETURN VALUES

     On success, function dwarf_get_section_bytes() returns a pointer to a ELF section byte stream.  In case of an error, function
     dwarf_get_section_bytes() will return NULL and set the argument err.

ERRORS

     Function dwarf_get_section_bytes() can fail with:

     [DW_DLE_ARGUMENT]	One of the arguments dbg, elf_section_index, or length was NULL.

     [DW_DLE_NO_ENTRY]	There were no more ELF sections to retrieve, or the function was called before a call to dwarf_transform_to_disk_form(3).

EXAMPLES

     To generate and retrieve ELF section byte streams, use:

	   Dwarf_P_Debug dbg;
	   Dwarf_Signed count, i, sec_index;
	   Dwarf_Unsigned len;
	   Dwarf_Ptr bytes;
	   Dwarf_Error de;

	   /* ... Assume that `dbg' refers to a DWARF producer instance,
	    * and that application code has added DWARF debugging
	    * information to the producer instance. ...
	    */
	   if ((count = dwarf_transform_to_disk_form(dbg, &de)) ==
	       DW_DLV_NOCOUNT) {
		   warnx("dwarf_transform_to_disk_form failed: %s",
		       dwarf_errmsg(-1));
		   return;
	   }

	   /* Retrieve section data. */
	   for (i = 0; i < count; i++) {
		   bytes = dwarf_get_section_bytes(dbg, i, &sec_index, &len,
		       &de);
		   if (bytes == NULL) {
			   warnx("dwarf_get_section_bytes failed: %s",
			       dwarf_errmsg(-1));
			   continue;
		   }
		   /* ... use the returned byte stream ... */
	   }

	   /* Release resources. */
	   dwarf_producer_finish(dbg, &de);

SEE ALSO

     dwarf(3), dwarf_reset_section_bytes(3), dwarf_producer_finish(3), dwarf_producer_init(3), dwarf_producer_init_b(3),
     dwarf_transform_to_disk_form(3)

BSD
								  August 26, 2011							       BSD