/*****************************************************************************\ * lbtable.c ***************************************************************************** * Copyright (C) 2002-2005 The Regents of the University of California. * Produced at the Lawrence Livermore National Laboratory. * Written by Dave Peterson <dsp@llnl.gov> <dave_peterson@pobox.com> * and Stefan Reinauer <stepan@openbios.org>. * UCRL-CODE-2003-012 * All rights reserved. * * This file is part of nvramtool, a utility for reading/writing coreboot * parameters and displaying information from the coreboot table. * For details, see http://coreboot.org/nvramtool. * * Please also read the file DISCLAIMER which is included in this software * distribution. * * This program is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License (as published by the * Free Software Foundation) version 2, dated June 1991. * * This program is distributed in the hope that it will be useful, but * WITHOUT ANY WARRANTY; without even the IMPLIED WARRANTY OF * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the terms and * conditions of the GNU General Public License for more details. \*****************************************************************************/ #include <stdint.h> #include <inttypes.h> #include <string.h> #ifndef __MINGW32__ #include <sys/mman.h> #endif #include "common.h" #include "coreboot_tables.h" #include "ip_checksum.h" #include "lbtable.h" #include "layout.h" #include "cmos_lowlevel.h" #include "hexdump.h" #include "cbfs.h" typedef void (*lbtable_print_fn_t) (const struct lb_record * rec); /* This structure represents an item in the coreboot table that may be * displayed using the -l option. */ typedef struct { uint32_t tag; const char *name; const char *description; const char *nofound_msg; lbtable_print_fn_t print_fn; } lbtable_choice_t; typedef struct { unsigned long start; /* address of first byte of memory range */ unsigned long end; /* address of last byte of memory range */ } mem_range_t; static const struct lb_header *lbtable_scan(unsigned long start, unsigned long end, int *bad_header_count, int *bad_table_count); static const char *lbrec_tag_to_str(uint32_t tag); static void memory_print_fn(const struct lb_record *rec); static void mainboard_print_fn(const struct lb_record *rec); static void cmos_opt_table_print_fn(const struct lb_record *rec); static void print_option_record(const struct cmos_entries *cmos_entry); static void print_enum_record(const struct cmos_enums *cmos_enum); static void print_defaults_record(const struct cmos_defaults *cmos_defaults); static void print_unknown_record(const struct lb_record *cmos_item); static void option_checksum_print_fn(const struct lb_record *rec); static void string_print_fn(const struct lb_record *rec); static const char memory_desc[] = " This shows information about system memory.\n"; static const char mainboard_desc[] = " This shows information about your mainboard.\n"; static const char version_desc[] = " This shows coreboot version information.\n"; static const char extra_version_desc[] = " This shows extra coreboot version information.\n"; static const char build_desc[] = " This shows coreboot build information.\n"; static const char compile_time_desc[] = " This shows when coreboot was compiled.\n"; static const char compile_by_desc[] = " This shows who compiled coreboot.\n"; static const char compile_host_desc[] = " This shows the name of the machine that compiled coreboot.\n"; static const char compile_domain_desc[] = " This shows the domain name of the machine that compiled coreboot.\n"; static const char compiler_desc[] = " This shows the name of the compiler used to build coreboot.\n"; static const char linker_desc[] = " This shows the name of the linker used to build coreboot.\n"; static const char assembler_desc[] = " This shows the name of the assembler used to build coreboot.\n"; static const char cmos_opt_table_desc[] = " This does a low-level dump of the CMOS option table. The table " "contains\n" " information about the layout of the values that coreboot stores in\n" " nonvolatile RAM.\n"; static const char option_checksum_desc[] = " This shows the location of the CMOS checksum and the area over which it " "is\n" " calculated.\n"; static const char generic_nofound_msg[] = "%s: Item %s not found in coreboot table.\n"; static const char nofound_msg_cmos_opt_table[] = "%s: Item %s not found in coreboot table. Apparently, the " "coreboot installed on this system was built without specifying " "CONFIG_HAVE_OPTION_TABLE.\n"; static const char nofound_msg_option_checksum[] = "%s: Item %s not found in coreboot table. Apparently, you are " "using coreboot v1.\n"; int fd; /* This is the number of items from the coreboot table that may be displayed * using the -l option. */ #define NUM_LBTABLE_CHOICES 14 /* These represent the various items from the coreboot table that may be * displayed using the -l option. */ static const lbtable_choice_t lbtable_choices[NUM_LBTABLE_CHOICES] = { {LB_TAG_MEMORY, "memory", memory_desc, generic_nofound_msg, memory_print_fn}, {LB_TAG_MAINBOARD, "mainboard", mainboard_desc, generic_nofound_msg, mainboard_print_fn}, {LB_TAG_VERSION, "version", version_desc, generic_nofound_msg, string_print_fn}, {LB_TAG_EXTRA_VERSION, "extra_version", extra_version_desc, generic_nofound_msg, string_print_fn}, {LB_TAG_BUILD, "build", build_desc, generic_nofound_msg, string_print_fn}, {LB_TAG_COMPILE_TIME, "compile_time", compile_time_desc, generic_nofound_msg, string_print_fn}, {LB_TAG_COMPILE_BY, "compile_by", compile_by_desc, generic_nofound_msg, string_print_fn}, {LB_TAG_COMPILE_HOST, "compile_host", compile_host_desc, generic_nofound_msg, string_print_fn}, {LB_TAG_COMPILE_DOMAIN, "compile_domain", compile_domain_desc, generic_nofound_msg, string_print_fn}, {LB_TAG_COMPILER, "compiler", compiler_desc, generic_nofound_msg, string_print_fn}, {LB_TAG_LINKER, "linker", linker_desc, generic_nofound_msg, string_print_fn}, {LB_TAG_ASSEMBLER, "assembler", assembler_desc, generic_nofound_msg, string_print_fn}, {LB_TAG_CMOS_OPTION_TABLE, "cmos_opt_table", cmos_opt_table_desc, nofound_msg_cmos_opt_table, cmos_opt_table_print_fn}, {LB_TAG_OPTION_CHECKSUM, "option_checksum", option_checksum_desc, nofound_msg_option_checksum, option_checksum_print_fn} }; /* The coreboot table resides in low physical memory, which we access using * /dev/mem. These are ranges of physical memory that should be scanned for a * coreboot table. */ #define NUM_MEM_RANGES 2 static const mem_range_t mem_ranges[NUM_MEM_RANGES] = { {0x00000000, 0x00000fff}, {0x000f0000, 0x000fffff} }; /* Pointer to low physical memory that we access by calling mmap() on * /dev/mem. */ static const void *low_phys_mem; /* impossible value since not page aligned: first map request will happen */ static unsigned long low_phys_base = 0x1; /* count of mapped pages */ static unsigned long mapped_pages = 0; /* Pointer to coreboot table. */ static const struct lb_header *lbtable = NULL; static const hexdump_format_t format = { 12, 4, " ", " | ", " ", " | ", '.' }; /**************************************************************************** * vtophys * * Convert a virtual address to a physical address. 'vaddr' is a virtual * address in the address space of the current process. It points to * somewhere in the chunk of memory that we mapped by calling mmap() on * /dev/mem. This macro converts 'vaddr' to a physical address. ****************************************************************************/ #define vtophys(vaddr) (((unsigned long) vaddr) - \ ((unsigned long) low_phys_mem) + low_phys_base) /**************************************************************************** * phystov * * Convert a physical address to a virtual address. 'paddr' is a physical * address. This macro converts 'paddr' to a virtual address in the address * space of the current process. The virtual to physical mapping was set up * by calling mmap() on /dev/mem. ****************************************************************************/ #define phystov(paddr) (((unsigned long) low_phys_mem) + \ ((unsigned long) paddr) - low_phys_base) /**************************************************************************** * map_pages * * Maps just enough pages to cover base_address + length * and updates affected variables ****************************************************************************/ static void map_pages(unsigned long base_address, unsigned long length) { unsigned long num_pages = (length + (base_address & (getpagesize() - 1)) + getpagesize() - 1) >> 12; base_address &= ~(getpagesize() - 1); /* no need to do anything */ if ((low_phys_base == base_address) && (mapped_pages == num_pages)) { return; } if (low_phys_mem) { munmap((void *)low_phys_mem, mapped_pages << 12); } if ((low_phys_mem = mmap(NULL, num_pages << 12, PROT_READ, MAP_SHARED, fd, (off_t) base_address)) == MAP_FAILED) { fprintf(stderr, "%s: Failed to mmap /dev/mem at %lx: %s\n", prog_name, base_address, strerror(errno)); exit(1); } low_phys_base = base_address; } /**************************************************************************** * get_lbtable * * Find the coreboot table and set global variable lbtable to point to it. ****************************************************************************/ void get_lbtable(void) { int i, bad_header_count, bad_table_count, bad_headers, bad_tables; if (lbtable != NULL) return; /* The coreboot table is located in low physical memory, which may be * conveniently accessed by calling mmap() on /dev/mem. */ if ((fd = open("/dev/mem", O_RDONLY, 0)) < 0) { fprintf(stderr, "%s: Can not open /dev/mem for reading: %s\n", prog_name, strerror(errno)); exit(1); } bad_header_count = 0; bad_table_count = 0; for (i = 0; i < NUM_MEM_RANGES; i++) { lbtable = lbtable_scan(mem_ranges[i].start, mem_ranges[i].end, &bad_headers, &bad_tables); if (lbtable != NULL) return; /* success: we found it! */ bad_header_count += bad_headers; bad_table_count += bad_tables; } fprintf(stderr, "%s: coreboot table not found. coreboot does not appear to\n" " be installed on this system. Scanning for the table " "produced the\n" " following results:\n\n" " %d valid signatures were found with bad header " "checksums.\n" " %d valid headers were found with bad table " "checksums.\n", prog_name, bad_header_count, bad_table_count); exit(1); } /**************************************************************************** * dump_lbtable * * Do a low-level dump of the coreboot table. ****************************************************************************/ void dump_lbtable(void) { const char *p, *data; uint32_t bytes_processed; const struct lb_record *lbrec; p = ((const char *)lbtable) + lbtable->header_bytes; printf("Coreboot table at physical address 0x%lx:\n" " signature: 0x%x (ASCII: %c%c%c%c)\n" " header_bytes: 0x%x (decimal: %d)\n" " header_checksum: 0x%x (decimal: %d)\n" " table_bytes: 0x%x (decimal: %d)\n" " table_checksum: 0x%x (decimal: %d)\n" " table_entries: 0x%x (decimal: %d)\n\n", vtophys(lbtable), lbtable->signature32, lbtable->signature[0], lbtable->signature[1], lbtable->signature[2], lbtable->signature[3], lbtable->header_bytes, lbtable->header_bytes, lbtable->header_checksum, lbtable->header_checksum, lbtable->table_bytes, lbtable->table_bytes, lbtable->table_checksum, lbtable->table_checksum, lbtable->table_entries, lbtable->table_entries); if ((lbtable->table_bytes == 0) != (lbtable->table_entries == 0)) { printf ("Inconsistent values for table_bytes and table_entries!!!\n" "They should be either both 0 or both nonzero.\n"); return; } if (lbtable->table_bytes == 0) { printf("The coreboot table is empty!!!\n"); return; } for (bytes_processed = 0;;) { lbrec = (const struct lb_record *)&p[bytes_processed]; printf(" %s record at physical address 0x%lx:\n" " tag: 0x%x (decimal: %d)\n" " size: 0x%x (decimal: %d)\n" " data:\n", lbrec_tag_to_str(lbrec->tag), vtophys(lbrec), lbrec->tag, lbrec->tag, lbrec->size, lbrec->size); data = ((const char *)lbrec) + sizeof(*lbrec); hexdump(data, lbrec->size - sizeof(*lbrec), vtophys(data), stdout, &format); bytes_processed += lbrec->size; if (bytes_processed >= lbtable->table_bytes) break; printf("\n"); } } /**************************************************************************** * list_lbtable_choices * * List names and informational blurbs for items from the coreboot table * that may be displayed using the -l option. ****************************************************************************/ void list_lbtable_choices(void) { int i; for (i = 0;;) { printf("%s:\n%s", lbtable_choices[i].name, lbtable_choices[i].description); if (++i >= NUM_LBTABLE_CHOICES) break; printf("\n"); } } /**************************************************************************** * list_lbtable_item * * Show the coreboot table item specified by 'item'. ****************************************************************************/ void list_lbtable_item(const char item[]) { int i; const struct lb_record *rec; for (i = 0; i < NUM_LBTABLE_CHOICES; i++) { if (strcmp(item, lbtable_choices[i].name) == 0) break; } if (i == NUM_LBTABLE_CHOICES) { fprintf(stderr, "%s: Invalid coreboot table item %s.\n", prog_name, item); exit(1); } if ((rec = find_lbrec(lbtable_choices[i].tag)) == NULL) { fprintf(stderr, lbtable_choices[i].nofound_msg, prog_name, lbtable_choices[i].name); exit(1); } lbtable_choices[i].print_fn(rec); } /**************************************************************************** * lbtable_scan * * Scan the chunk of memory specified by 'start' and 'end' for a coreboot * table. The first 4 bytes of the table are marked by the signature * { 'L', 'B', 'I', 'O' }. 'start' and 'end' indicate the addresses of the * first and last bytes of the chunk of memory to be scanned. For instance, * values of 0x10000000 and 0x1000ffff for 'start' and 'end' specify a 64k * chunk of memory starting at address 0x10000000. 'start' and 'end' are * physical addresses. * * If a coreboot table is found, return a pointer to it. Otherwise return * NULL. On return, *bad_header_count and *bad_table_count are set as * follows: * * *bad_header_count: * Indicates the number of times in which a valid signature was found * but the header checksum was invalid. * * *bad_table_count: * Indicates the number of times in which a header with a valid * checksum was found but the table checksum was invalid. ****************************************************************************/ static const struct lb_header *lbtable_scan(unsigned long start, unsigned long end, int *bad_header_count, int *bad_table_count) { static const char signature[4] = { 'L', 'B', 'I', 'O' }; const struct lb_header *table; const struct lb_forward *forward; unsigned long p; uint32_t sig; assert(end >= start); memcpy(&sig, signature, sizeof(sig)); table = NULL; *bad_header_count = 0; *bad_table_count = 0; /* Look for signature. Table is aligned on 16-byte boundary. Therefore * only check every fourth 32-bit memory word. As the loop is coded below, * this function will behave in a reasonable manner for ALL possible values * for 'start' and 'end': even weird boundary cases like 0x00000000 and * 0xffffffff on a 32-bit architecture. */ map_pages(start, end - start); for (p = start; (p <= end) && (end - p >= (sizeof(uint32_t) - 1)); p += 4) { if (*(uint32_t*)phystov(p) != sig) continue; /* We found a valid signature. */ table = (const struct lb_header *)phystov(p); /* validate header checksum */ if (compute_ip_checksum((void *)table, sizeof(*table))) { (*bad_header_count)++; continue; } map_pages(p, table->table_bytes + sizeof(*table)); /* validate table checksum */ if (table->table_checksum != compute_ip_checksum(((char *)table) + sizeof(*table), table->table_bytes)) { (*bad_table_count)++; continue; } /* checksums are ok: we found it! */ /* But it may just be a forwarding table, so look if there's a forwarder */ lbtable = table; forward = (struct lb_forward *)find_lbrec(LB_TAG_FORWARD); lbtable = NULL; if (forward) { uint64_t new_phys = forward->forward; table = lbtable_scan(new_phys, new_phys + getpagesize(), bad_header_count, bad_table_count); } return table; } return NULL; } /**************************************************************************** * find_lbrec * * Find the record in the coreboot table that matches 'tag'. Return pointer * to record on success or NULL if record not found. ****************************************************************************/ const struct lb_record *find_lbrec(uint32_t tag) { const char *p; uint32_t bytes_processed; const struct lb_record *lbrec; p = ((const char *)lbtable) + lbtable->header_bytes; for (bytes_processed = 0; bytes_processed < lbtable->table_bytes; bytes_processed += lbrec->size) { lbrec = (const struct lb_record *)&p[bytes_processed]; if (lbrec->tag == tag) return lbrec; } return NULL; } /**************************************************************************** * lbrec_tag_to_str * * Return a pointer to the string representation of the given coreboot table * tag. ****************************************************************************/ static const char *lbrec_tag_to_str(uint32_t tag) { switch (tag) { case LB_TAG_UNUSED: return "UNUSED"; case LB_TAG_MEMORY: return "MEMORY"; case LB_TAG_HWRPB: return "HWRPB"; case LB_TAG_MAINBOARD: return "MAINBOARD"; case LB_TAG_VERSION: return "VERSION"; case LB_TAG_EXTRA_VERSION: return "EXTRA_VERSION"; case LB_TAG_BUILD: return "BUILD"; case LB_TAG_COMPILE_TIME: return "COMPILE_TIME"; case LB_TAG_COMPILE_BY: return "COMPILE_BY"; case LB_TAG_COMPILE_HOST: return "COMPILE_HOST"; case LB_TAG_COMPILE_DOMAIN: return "COMPILE_DOMAIN"; case LB_TAG_COMPILER: return "COMPILER"; case LB_TAG_LINKER: return "LINKER"; case LB_TAG_ASSEMBLER: return "ASSEMBLER"; case LB_TAG_SERIAL: return "SERIAL"; case LB_TAG_CONSOLE: return "CONSOLE"; case LB_TAG_FORWARD: return "FORWARD"; case LB_TAG_CMOS_OPTION_TABLE: return "CMOS_OPTION_TABLE"; case LB_TAG_OPTION_CHECKSUM: return "OPTION_CHECKSUM"; default: break; } return "UNKNOWN"; } /**************************************************************************** * memory_print_fn * * Display function for 'memory' item of coreboot table. ****************************************************************************/ static void memory_print_fn(const struct lb_record *rec) { const struct lb_memory *p; const char *mem_type; const struct lb_memory_range *ranges; uint64_t size, start, end; int i, entries; p = (const struct lb_memory *)rec; entries = (p->size - sizeof(*p)) / sizeof(p->map[0]); ranges = p->map; if (entries == 0) { printf("No memory ranges were found.\n"); return; } for (i = 0;;) { switch (ranges[i].type) { case LB_MEM_RAM: mem_type = "AVAILABLE"; break; case LB_MEM_RESERVED: mem_type = "RESERVED"; break; case LB_MEM_TABLE: mem_type = "CONFIG_TABLE"; break; default: mem_type = "UNKNOWN"; break; } size = unpack_lb64(ranges[i].size); start = unpack_lb64(ranges[i].start); end = start + size - 1; printf("%s memory:\n" " from physical addresses 0x%016" PRIx64 " to 0x%016" PRIx64 "\n size is 0x%016" PRIx64 " bytes (%" PRId64 " in decimal)\n", mem_type, start, end, size, size); if (++i >= entries) break; printf("\n"); } } /**************************************************************************** * mainboard_print_fn * * Display function for 'mainboard' item of coreboot table. ****************************************************************************/ static void mainboard_print_fn(const struct lb_record *rec) { const struct lb_mainboard *p; p = (const struct lb_mainboard *)rec; printf("Vendor: %s\n" "Part number: %s\n", &p->strings[p->vendor_idx], &p->strings[p->part_number_idx]); } /**************************************************************************** * cmos_opt_table_print_fn * * Display function for 'cmos_opt_table' item of coreboot table. ****************************************************************************/ static void cmos_opt_table_print_fn(const struct lb_record *rec) { const struct cmos_option_table *p; const struct lb_record *cmos_item; uint32_t bytes_processed, bytes_for_entries; const char *q; p = (const struct cmos_option_table *)rec; q = ((const char *)p) + p->header_length; bytes_for_entries = p->size - p->header_length; printf("CMOS option table at physical address 0x%lx:\n" " tag: 0x%x (decimal: %d)\n" " size: 0x%x (decimal: %d)\n" " header_length: 0x%x (decimal: %d)\n\n", vtophys(p), p->tag, p->tag, p->size, p->size, p->header_length, p->header_length); if (p->header_length > p->size) { printf ("Header length for CMOS option table is greater than the size " "of the entire table including header!!!\n"); return; } if (bytes_for_entries == 0) { printf("The CMOS option table is empty!!!\n"); return; } for (bytes_processed = 0;;) { cmos_item = (const struct lb_record *)&q[bytes_processed]; switch (cmos_item->tag) { case LB_TAG_OPTION: print_option_record((const struct cmos_entries *) cmos_item); break; case LB_TAG_OPTION_ENUM: print_enum_record((const struct cmos_enums *)cmos_item); break; case LB_TAG_OPTION_DEFAULTS: print_defaults_record((const struct cmos_defaults *) cmos_item); break; default: print_unknown_record(cmos_item); break; } bytes_processed += cmos_item->size; if (bytes_processed >= bytes_for_entries) break; printf("\n"); } } /**************************************************************************** * print_option_record * * Display "option" record from CMOS option table. ****************************************************************************/ static void print_option_record(const struct cmos_entries *cmos_entry) { static const size_t S_BUFSIZE = 80; char s[S_BUFSIZE]; switch (cmos_entry->config) { case 'e': strcpy(s, "ENUM"); break; case 'h': strcpy(s, "HEX"); break; case 'r': strcpy(s, "RESERVED"); break; default: snprintf(s, S_BUFSIZE, "UNKNOWN: value is 0x%x (decimal: %d)", cmos_entry->config, cmos_entry->config); break; } printf(" OPTION record at physical address 0x%lx:\n" " tag: 0x%x (decimal: %d)\n" " size: 0x%x (decimal: %d)\n" " bit: 0x%x (decimal: %d)\n" " length: 0x%x (decimal: %d)\n" " config: %s\n" " config_id: 0x%x (decimal: %d)\n" " name: %s\n", vtophys(cmos_entry), cmos_entry->tag, cmos_entry->tag, cmos_entry->size, cmos_entry->size, cmos_entry->bit, cmos_entry->bit, cmos_entry->length, cmos_entry->length, s, cmos_entry->config_id, cmos_entry->config_id, cmos_entry->name); } /**************************************************************************** * print_enum_record * * Display "enum" record from CMOS option table. ****************************************************************************/ static void print_enum_record(const struct cmos_enums *cmos_enum) { printf(" ENUM record at physical address 0x%lx:\n" " tag: 0x%x (decimal: %d)\n" " size: 0x%x (decimal: %d)\n" " config_id: 0x%x (decimal: %d)\n" " value: 0x%x (decimal: %d)\n" " text: %s\n", vtophys(cmos_enum), cmos_enum->tag, cmos_enum->tag, cmos_enum->size, cmos_enum->size, cmos_enum->config_id, cmos_enum->config_id, cmos_enum->value, cmos_enum->value, cmos_enum->text); } /**************************************************************************** * print_defaults_record * * Display "defaults" record from CMOS option table. ****************************************************************************/ static void print_defaults_record(const struct cmos_defaults *cmos_defaults) { printf(" DEFAULTS record at physical address 0x%lx:\n" " tag: 0x%x (decimal: %d)\n" " size: 0x%x (decimal: %d)\n" " name_length: 0x%x (decimal: %d)\n" " name: %s\n" " default_set:\n", vtophys(cmos_defaults), cmos_defaults->tag, cmos_defaults->tag, cmos_defaults->size, cmos_defaults->size, cmos_defaults->name_length, cmos_defaults->name_length, cmos_defaults->name); hexdump(cmos_defaults->default_set, CMOS_IMAGE_BUFFER_SIZE, vtophys(cmos_defaults->default_set), stdout, &format); } /**************************************************************************** * print_unknown_record * * Display record of unknown type from CMOS option table. ****************************************************************************/ static void print_unknown_record(const struct lb_record *cmos_item) { const char *data; printf(" UNKNOWN record at physical address 0x%lx:\n" " tag: 0x%x (decimal: %d)\n" " size: 0x%x (decimal: %d)\n" " data:\n", vtophys(cmos_item), cmos_item->tag, cmos_item->tag, cmos_item->size, cmos_item->size); data = ((const char *)cmos_item) + sizeof(*cmos_item); hexdump(data, cmos_item->size - sizeof(*cmos_item), vtophys(data), stdout, &format); } /**************************************************************************** * option_checksum_print_fn * * Display function for 'option_checksum' item of coreboot table. ****************************************************************************/ static void option_checksum_print_fn(const struct lb_record *rec) { struct cmos_checksum *p; p = (struct cmos_checksum *)rec; printf("CMOS checksum from bit %d to bit %d\n" "at position %d is type %s.\n", p->range_start, p->range_end, p->location, (p->type == CHECKSUM_PCBIOS) ? "PC BIOS" : "NONE"); } /**************************************************************************** * string_print_fn * * Display function for a generic item of coreboot table that simply * consists of a string. ****************************************************************************/ static void string_print_fn(const struct lb_record *rec) { const struct lb_string *p; p = (const struct lb_string *)rec; printf("%s\n", p->string); }