depmod.c

用于linux2.6内核支持模块的插入和卸载

/* New simplified depmod without backwards compat stuff and not
   requiring ksyms.

   (C) 2002 Rusty Russell IBM Corporation
 */
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <getopt.h>
#include <string.h>
#include <errno.h>
#include <unistd.h>
#include <elf.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <dirent.h>
#include <sys/utsname.h>
#include <sys/mman.h>

#include "zlibsupport.h"
#include "depmod.h"
#include "moduleops.h"
#include "tables.h"

#include "testing.h"

/* I hate strcmp. */
#define streq(a,b) (strcmp((a),(b)) == 0)

#ifndef MODULE_DIR
#define MODULE_DIR "/lib/modules/"
#endif

static int verbose;
static unsigned int skipchars;

void fatal(const char *fmt, ...)
{
	va_list arglist;

	fprintf(stderr, "FATAL: ");

	va_start(arglist, fmt);
	vfprintf(stderr, fmt, arglist);
	va_end(arglist);

	exit(1);
}

void warn(const char *fmt, ...)
{
	va_list arglist;

	fprintf(stderr, "WARNING: ");

	va_start(arglist, fmt);
	vfprintf(stderr, fmt, arglist);
	va_end(arglist);
}

void *do_nofail(void *ptr, const char *file, int line, const char *expr)
{
	if (!ptr) {
		fatal("Memory allocation failure %s line %d: %s.\n",
		      file, line, expr);
	}
	return ptr;
}

#define SYMBOL_HASH_SIZE 1024
struct symbol
{
	struct symbol *next;
	struct module *owner;
	char name[0];
};

static struct symbol *symbolhash[SYMBOL_HASH_SIZE];

/* This is based on the hash agorithm from gdbm, via tdb */
static inline unsigned int tdb_hash(const char *name)
{
	unsigned value;	/* Used to compute the hash value.  */
	unsigned   i;	/* Used to cycle through random values. */

	/* Set the initial value from the key size. */
	for (value = 0x238F13AF * strlen(name), i=0; name[i]; i++)
		value = (value + (((unsigned char *)name)[i] << (i*5 % 24)));

	return (1103515243 * value + 12345);
}

void add_symbol(const char *name, struct module *owner)
{
	unsigned int hash;
	struct symbol *new = NOFAIL(malloc(sizeof *new + strlen(name) + 1));

	new->owner = owner;
	strcpy(new->name, name);

	hash = tdb_hash(name) % SYMBOL_HASH_SIZE;
	new->next = symbolhash[hash];
	symbolhash[hash] = new;
}

static int print_unknown;

struct module *find_symbol(const char *name, const char *modname, int weak)
{
	struct symbol *s;

	/* For our purposes, .foo matches foo.  PPC64 needs this. */
	if (name[0] == '.')
		name++;

	for (s = symbolhash[tdb_hash(name) % SYMBOL_HASH_SIZE]; s; s=s->next) {
		if (streq(s->name, name))
			return s->owner;
	}

	if (print_unknown && !weak)
		warn("%s needs unknown symbol %s\n", modname, name);

	return NULL;
}

void add_dep(struct module *mod, struct module *depends_on)
{
	unsigned int i;

	for (i = 0; i < mod->num_deps; i++)
		if (mod->deps[i] == depends_on)
			return;

	mod->deps = realloc(mod->deps, sizeof(mod->deps[0])*(mod->num_deps+1));
	mod->deps[mod->num_deps++] = depends_on;
}

static void load_system_map(const char *filename)
{
	FILE *system_map;
	char line[10240];

	system_map = fopen(filename, "r");
	if (!system_map)
		fatal("Could not open '%s': %s\n", filename, strerror(errno));

	/* eg. c0294200 R __ksymtab_devfs_alloc_devnum */
	while (fgets(line, sizeof(line)-1, system_map)) {
		char *ptr;

		/* Snip \n */
		ptr = strchr(line, '\n');
		*ptr = '\0';

		ptr = strchr(line, ' ');
		if (!ptr || !(ptr = strchr(ptr + 1, ' ')))
			continue;

		/* Covers gpl-only and normal symbols. */
		if (strncmp(ptr+1, "__ksymtab_", strlen("__ksymtab_")) == 0)
			add_symbol(ptr+1+strlen("__ksymtab_"), NULL);
	}

	/* __this_module is magic inserted by kernel loader. */
	add_symbol("__this_module", NULL);
	/* On S390, this is faked up too */
	add_symbol("_GLOBAL_OFFSET_TABLE_", NULL);
}

static struct option options[] = { { "all", 0, NULL, 'a' },
				   { "quick", 0, NULL, 'A' },
				   { "basedir", 1, NULL, 'b' },
				   { "errsyms", 0, NULL, 'e' },
				   { "filesyms", 1, NULL, 'F' },
				   { "help", 0, NULL, 'h' },
				   { "show", 0, NULL, 'n' },
				   { "dry-run", 0, NULL, 'n' },
				   { "quiet", 0, NULL, 'q' },
				   { "root", 0, NULL, 'r' },
				   { "unresolved-error", 0, NULL, 'u' },
				   { "verbose", 0, NULL, 'v' },
				   { "version", 0, NULL, 'V' },
				   /* Obsolete, but we need to parse it. */
				   { "config", 1, NULL, 'C' },
				   { NULL, 0, NULL, 0 } };

/* Version number or module name?  Don't assume extension. */
static int is_version_number(const char *version)
{
	unsigned int dummy;

	return (sscanf(version, "%u.%u.%u", &dummy, &dummy, &dummy) == 3);
}

static int old_module_version(const char *version)
{
	/* Expect three part version. */
	unsigned int major, sub, minor;

	sscanf(version, "%u.%u.%u", &major, &sub, &minor);

	if (major > 2) return 0;
	if (major < 2) return 1;

	/* 2.x */
	if (sub > 5) return 0;
	if (sub < 5) return 1;

	/* 2.5.x */
	if (minor >= 48) return 0;
	return 1;
}

static void exec_old_depmod(char *argv[])
{
	char *sep;
	char pathname[strlen(argv[0])+1];
	char oldname[strlen("depmod") + strlen(argv[0]) + sizeof(".old")];

	memset(pathname, 0, strlen(argv[0])+1);
	sep = strrchr(argv[0], '/');
	if (sep)
		memcpy(pathname, argv[0], sep - argv[0]+1);
	sprintf(oldname, "%s%s.old", pathname, "depmod");

	/* Recursion detection: we need an env var since we can't
	   change argv[0] (as older modutils uses it to determine
	   behavior). */
	if (getenv("MODULE_RECURSE"))
		return;
	setenv("MODULE_RECURSE", "y", 0);

	execvp(oldname, argv);
	fprintf(stderr,
		"Version requires old depmod, but couldn't run %s: %s\n",
		oldname, strerror(errno));
	exit(2);
}

static void print_usage(const char *name)
{
	fprintf(stderr,
	"%s " VERSION " -- part of " PACKAGE "\n"
	"%s -[aA] [-n -e -v -q -V -r -u]\n"
	"      [-b basedirectory] [forced_version]\n"
	"depmod [-n -e -v -q -r -u] [-F kernelsyms] module1.o module2.o ...\n"
	"If no arguments (except options) are given, \"depmod -a\" is assumed\n"
	"\n"
	"depmod will output a dependancy list suitable for the modprobe utility.\n"
	"\n"
	"\n"
	"Options:\n"
	"\t-a, --all            Probe all modules\n"
	"\t-n, --show           Write the dependency file on stdout only\n"
	"\t-V, --version        Print the release version\n"
	"\t-h, --help           Print this usage message\n"
	"\n"
	"The following options are useful for people managing distributions:\n"
	"\t-b basedirectory\n"
	"\t    --basedir basedirectory    Use an image of a module tree.\n"
	"\t-F kernelsyms\n"
	"\t    --filesyms kernelsyms      Use the file instead of the\n"
	"\t                               current kernel symbols.\n",
	"depmod", "depmod");
}

static int ends_in(const char *name, const char *ext)
{
	unsigned int namelen, extlen;

	/* Grab lengths */
	namelen = strlen(name);
	extlen = strlen(ext);

	if (namelen < extlen) return 0;

	if (streq(name + namelen - extlen, ext))
		return 1;
	return 0;
}

static struct module *grab_module(const char *dirname,
				  const char *filename,
				  struct module *next)
{
	struct module *new;

	new = NOFAIL(malloc(sizeof(*new)
			    + strlen(dirname) + 1 + strlen(filename) + 1));
	sprintf(new->pathname, "%s/%s", dirname, filename);
	INIT_LIST_HEAD(&new->dep_list);

	new->data = grab_file(new->pathname, &new->len);
	if (!new->data) {
		warn("Can't read module %s: %s\n",
		     new->pathname, strerror(errno));
		goto fail_data;
	}

	/* "\177ELF" <byte> where byte = 001 for 32-bit, 002 for 64 */
	if (memcmp(new->data, ELFMAG, SELFMAG) != 0) {
		warn("Module %s is not an elf object\n", new->pathname);
		goto fail;
	}

	switch (((char *)new->data)[EI_CLASS]) {
	case ELFCLASS32:
		new->ops = &mod_ops32;
		break;
	case ELFCLASS64:
		new->ops = &mod_ops64;
		break;
	default:
		warn("Module %s has elf unknown identifier %i\n",
		     new->pathname, ((char *)new->data)[EI_CLASS]);
		goto fail;
	}
	new->ops->load_symbols(new);
	new->ops->fetch_tables(new);

	new->next = next;
	return new;

fail:
	release_file(new->data, new->len);
fail_data:
	free(new);
	return next;
}

struct module_traverse
{
	struct module_traverse *prev;
	struct module *mod;
};

static int in_loop(struct module *mod, const struct module_traverse *traverse)
{
	const struct module_traverse *i;

	for (i = traverse; i; i = i->prev) {
		if (i->mod == mod)
			return 1;
	}
	return 0;
}

static char *basename(const char *name)
{
	const char *base = strrchr(name, '/');
	if (base) return (char *)base + 1;
	return (char *)name;
}

/* Assume we are doing all the modules, so only report each loop once. */
static void report_loop(const struct module *mod,
			const struct module_traverse *traverse)
{
	const struct module_traverse *i;

	/* Check that start is least alphabetically.  eg.  a depends
	   on b depends on a will get reported for a, not b.  */
	for (i = traverse->prev; i->prev; i = i->prev) {
		if (strcmp(mod->pathname, i->mod->pathname) > 0)
			return;
	}

	/* Is start in the loop?  If not, don't report now. eg. a
	   depends on b which depends on c which depends on b.  Don't
	   report when generating depends for a. */
	if (mod != i->mod)
		return;

	warn("Loop detected: %s ", mod->pathname);
	for (i = traverse->prev; i->prev; i = i->prev)
		fprintf(stderr, "needs %s ", basename(i->mod->pathname));
	fprintf(stderr, "which needs %s again!\n", basename(mod->pathname));
}

/* This is damn slow, but loops actually happen, and we don't want to
   just exit() and leave the user without any modules. */
static int has_dep_loop(struct module *module, struct module_traverse *prev)
{
	unsigned int i;
	struct module_traverse traverse = { .prev = prev, .mod = module };

	if (in_loop(module, prev)) {
		report_loop(module, &traverse);
		return 1;
	}