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STRUCTS_TYPE_STRUCT(3) Library Functions Manual STRUCTS_TYPE_STRUCT(3) NAME structs_type_struct -- structs types for C structures LIBRARY PDEL Library (libpdel, -lpdel) SYNOPSIS #include <sys/types.h> #include <stddef.h> #include <pdel/structs/structs.h> #include <pdel/structs/type/struct.h> STRUCTS_STRUCT_TYPE(struct_name, field_list); STRUCTS_STRUCT_FIELD(struct_name, field_name, field_type); STRUCTS_STRUCT_FIELD2(struct_name, field_name, display_name, field_type); DESCRIPTION The STRUCTS_STRUCT_TYPE() macro defines a structs(3) type (i.e., a struct structs_type) for describing the C structure struct struct_name. The field_list parameter must point to an array of struct structs_field structures describing the fields: /* This structure describes one field in a structure */ struct structs_field { const char *name; /* field name */ const struct structs_type *type; /* field type */ u_int16_t size; /* field size */ u_int16_t offset; /* field offset */ }; The fields need not be listed in the array in the same order as they are declared in the C structure. However, the array must be terminated with STRUCTS_STRUCT_FIELD_END, which is defined as follows: #define STRUCTS_STRUCT_FIELD_END { NULL, NULL, 0, 0 } The STRUCTS_STRUCT_FIELD() macro should be used to define an entry in the field array: field_name is the name of the field and field_type is a pointer to the structs(3) type describing the field. To define a field and give it a different structs(3) name than its name in the C structure, use STRUCTS_STRUCT_FIELD2() with the desired display_name in double quotes. SEE ALSO libpdel(3), structs(3), structs_type(3), structs_type_union(3) EXAMPLES The program below prints out the contents (as an ASCII string) of the field specified on the command line: #include <sys/types.h> #include <sys/socket.h> #include <netinet/in.h> #include <arpa/inet.h> #include <stdio.h> #include <stdlib.h> #include <err.h> #include <pdel/structs/structs.h> #include <pdel/structs/type/struct.h> #include <pdel/structs/type/string.h> #include <pdel/structs/type/ip4.h> #include <pdel/util/typed_mem.h> /* My structure */ struct foobar { char *name; u_int16_t index; struct in_addr ipaddr; }; /* Structs type describing a 'struct foobar' */ static const struct structs_field foobar_fields = { STRUCTS_STRUCT_FIELD(foobar, name, &structs_type_string), STRUCTS_STRUCT_FIELD(foobar, index, &structs_type_uint16), STRUCTS_STRUCT_FIELD(foobar, ipaddr, &structs_type_ip4), STRUCTS_STRUCT_FIELD_END }; static const struct structs_type foobar_type = STRUCTS_STRUCT_TYPE(foobar, &foobar_fields); int main(int argc, char **argv) { struct foobar f; const char *fieldname; char *fieldvalue; /* Initialize our structure with some contents */ if (structs_init(&foobar_type, NULL, &f) == -1) err(1, "structs_init"); f.index = 123; (void)inet_aton("12.34.56.78", &f.ipaddr); if (structs_set_string(&foobar_type, "name", "this is a string", &f, NULL, 0) == -1) err(1, "structs_set_string"); /* Get the requested field's name from the command line */ if (argc != 2) err(1, "usage: getfield <fieldname>"); fieldname = argv[1]; /* Display the requested field's value */ if ((fieldvalue = structs_get_string(&foobar_type, fieldname, &f, TYPED_MEM_TEMP)) == NULL) err(1, "%s", fieldname); printf("The value of field \"%s\" is: %s\n", fieldname, fieldvalue); /* Done, clean up */ FREE(TYPED_MEM_TEMP, fieldvalue); structs_free(&foobar_type, NULL, &f); return (0); } HISTORY The PDEL library was developed at Packet Design, LLC. http://www.packetdesign.com/ AUTHORS Archie Cobbs <archie@freebsd.org> FreeBSD ports 15.0 April 22, 2002 STRUCTS_TYPE_STRUCT(3)
NAME | LIBRARY | SYNOPSIS | DESCRIPTION | SEE ALSO | EXAMPLES | HISTORY | AUTHORS
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