/* * "Optimize" a list of dependencies as spit out by gcc -MD * for the kernel build * =========================================================================== * * Author       Kai Germaschewski * Copyright    2002 by Kai Germaschewski  <kai.germaschewski@gmx.de> * * This software may be used and distributed according to the terms * of the GNU General Public License, incorporated herein by reference. * * * Introduction: * * gcc produces a very nice and correct list of dependencies which * tells make when to remake a file. * * To use this list as-is however has the drawback that virtually * every file in the kernel includes autoconf.h. * * If the user re-runs make *config, autoconf.h will be * regenerated.  make notices that and will rebuild every file which * includes autoconf.h, i.e. basically all files. This is extremely * annoying if the user just changed CONFIG_HIS_DRIVER from n to m. * * So we play the same trick that "mkdep" played before. We replace * the dependency on autoconf.h by a dependency on every config * option which is mentioned in any of the listed prequisites. * * kconfig populates a tree in include/config/ with an empty file * for each config symbol and when the configuration is updated * the files representing changed config options are touched * which then let make pick up the changes and the files that use * the config symbols are rebuilt. * * So if the user changes his CONFIG_HIS_DRIVER option, only the objects * which depend on "include/linux/config/his/driver.h" will be rebuilt, * so most likely only his driver ;-) * * The idea above dates, by the way, back to Michael E Chastain, AFAIK. * * So to get dependencies right, there are two issues: * o if any of the files the compiler read changed, we need to rebuild * o if the command line given to the compile the file changed, we *   better rebuild as well. * * The former is handled by using the -MD output, the later by saving * the command line used to compile the old object and comparing it * to the one we would now use. * * Again, also this idea is pretty old and has been discussed on * kbuild-devel a long time ago. I don't have a sensibly working * internet connection right now, so I rather don't mention names * without double checking. * * This code here has been based partially based on mkdep.c, which * says the following about its history: * *   Copyright abandoned, Michael Chastain, <mailto:mec@shout.net>. *   This is a C version of syncdep.pl by Werner Almesberger. * * * It is invoked as * *   fixdep <depfile> <target> <cmdline> * * and will read the dependency file <depfile> * * The transformed dependency snipped is written to stdout. * * It first generates a line * *   cmd_<target> = <cmdline> * * and then basically copies the .<target>.d file to stdout, in the * process filtering out the dependency on autoconf.h and adding * dependencies on include/config/my/option.h for every * CONFIG_MY_OPTION encountered in any of the prequisites. * * It will also filter out all the dependencies on *.ver. We need * to make sure that the generated version checksum are globally up * to date before even starting the recursive build, so it's too late * at this point anyway. * * The algorithm to grep for "CONFIG_..." is bit unusual, but should * be fast ;-) We don't even try to really parse the header files, but * merely grep, i.e. if CONFIG_FOO is mentioned in a comment, it will * be picked up as well. It's not a problem with respect to * correctness, since that can only give too many dependencies, thus * we cannot miss a rebuild. Since people tend to not mention totally * unrelated CONFIG_ options all over the place, it's not an * efficiency problem either. * * (Note: it'd be easy to port over the complete mkdep state machine, *  but I don't think the added complexity is worth it) *//* * Note 2: if somebody writes HELLO_CONFIG_BOOM in a file, it will depend onto * CONFIG_BOOM. This could seem a bug (not too hard to fix), but please do not * fix it! Some UserModeLinux files (look at arch/um/) call CONFIG_BOOM as * UML_CONFIG_BOOM, to avoid conflicts with /usr/include/linux/autoconf.h, * through arch/um/include/uml-config.h; this fixdep "bug" makes sure that * those files will have correct dependencies. */ #include <sys/types.h>#include <sys/stat.h>#include <sys/mman.h>#include <unistd.h>#include <fcntl.h>#include <string.h>#include <stdlib.h>#include <stdio.h>#include <limits.h>#include <ctype.h>#include <arpa/inet.h> #define INT_CONF ntohl(0x434f4e46)#define INT_ONFI ntohl(0x4f4e4649)#define INT_NFIG ntohl(0x4e464947)#define INT_FIG_ ntohl(0x4649475f) char *target;char *depfile;char *cmdline; static void usage(void){	fprintf(stderr, "Usage: fixdep <depfile> <target> <cmdline>\n");	exit(1);} /* * Print out the commandline prefixed with cmd_<target filename> := */static void print_cmdline(void){	printf("cmd_%s := %s\n\n", target, cmdline);} struct item {	struct item	*next;	unsigned int	len;	unsigned int	hash;	char		name[0];}; #define HASHSZ 256static struct item *hashtab[HASHSZ]; static unsigned int strhash(const char *str, unsigned int sz){	/* fnv32 hash */	unsigned int i, hash = 2166136261U; 	for (i = 0; i < sz; i++)		hash = (hash ^ str[i]) * 0x01000193;	return hash;} /* * Lookup a value in the configuration string. */static int is_defined_config(const char *name, int len, unsigned int hash){	struct item *aux; 	for (aux = hashtab[hash % HASHSZ]; aux; aux = aux->next) {		if (aux->hash == hash && aux->len == len &&		    memcmp(aux->name, name, len) == 0)			return 1;	}	return 0;} /* * Add a new value to the configuration string. */static void define_config(const char *name, int len, unsigned int hash){	struct item *aux = malloc(sizeof(*aux) + len); 	if (!aux) {		perror("fixdep:malloc");		exit(1);	}	memcpy(aux->name, name, len);	aux->len = len;	aux->hash = hash;	aux->next = hashtab[hash % HASHSZ];	hashtab[hash % HASHSZ] = aux;} /* * Clear the set of configuration strings. */static void clear_config(void){	struct item *aux, *next;	unsigned int i; 	for (i = 0; i < HASHSZ; i++) {		for (aux = hashtab[i]; aux; aux = next) {			next = aux->next;			free(aux);		}		hashtab[i] = NULL;	}} /* * Record the use of a CONFIG_* word. */static void use_config(const char *m, int slen){	unsigned int hash = strhash(m, slen);	int c, i; 	if (is_defined_config(m, slen, hash))	    return; 	define_config(m, slen, hash); 	printf("    $(wildcard include/config/");	for (i = 0; i < slen; i++) {		c = m[i];		if (c == '_')			c = '/';		else			c = tolower(c);		putchar(c);	}	printf(".h) \\\n");} static void parse_config_file(const char *map, size_t len){	const int *end = (const int *) (map + len);	/* start at +1, so that p can never be < map */	const int *m   = (const int *) map + 1;	const char *p, *q; 	for (; m < end; m++) {		if (*m == INT_CONF) { p = (char *) m  ; goto conf; }		if (*m == INT_ONFI) { p = (char *) m-1; goto conf; }		if (*m == INT_NFIG) { p = (char *) m-2; goto conf; }		if (*m == INT_FIG_) { p = (char *) m-3; goto conf; }		continue;	conf:		if (p > map + len - 7)			continue;		if (memcmp(p, "CONFIG_", 7))			continue;		for (q = p + 7; q < map + len; q++) {			if (!(isalnum(*q) || *q == '_'))				goto found;		}		continue; 	found:		if (!memcmp(q - 7, "_MODULE", 7))			q -= 7;		if( (q-p-7) < 0 )			continue;		use_config(p+7, q-p-7);	}} /* test is s ends in sub */static int strrcmp(char *s, char *sub){	int slen = strlen(s);	int sublen = strlen(sub); 	if (sublen > slen)		return 1; 	return memcmp(s + slen - sublen, sub, sublen);} static void do_config_file(const char *filename){	struct stat st;	int fd;	void *map; 	fd = open(filename, O_RDONLY);	if (fd < 0) {		fprintf(stderr, "fixdep: error opening config file: ");		perror(filename);		exit(2);	}	fstat(fd, &st);	if (st.st_size == 0) {		close(fd);		return;	}	map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);	if ((long) map == -1) {		perror("fixdep: mmap");		close(fd);		return;	} 	parse_config_file(map, st.st_size); 	munmap(map, st.st_size); 	close(fd);} /* * Important: The below generated source_foo.o and deps_foo.o variable * assignments are parsed not only by make, but also by the rather simple * parser in scripts/mod/sumversion.c. */static void parse_dep_file(void *map, size_t len){	char *m = map;	char *end = m + len;	char *p;	char s[PATH_MAX];	int first; 	p = strchr(m, ':');	if (!p) {		fprintf(stderr, "fixdep: parse error\n");		exit(1);	}	memcpy(s, m, p-m); s[p-m] = 0;	m = p+1; 	clear_config(); 	first = 1;	while (m < end) {		while (m < end && (*m == ' ' || *m == '\\' || *m == '\n'))			m++;		p = m;		while (p < end && *p != ' ') p++;		if (p == end) {			do p--; while (!isalnum(*p));			p++;		}		memcpy(s, m, p-m); s[p-m] = 0;		if (strrcmp(s, "include/generated/autoconf.h") &&		    strrcmp(s, "arch/um/include/uml-config.h") &&		    strrcmp(s, "include/linux/kconfig.h") &&		    strrcmp(s, ".ver")) {			/*			 * Do not list the source file as dependency, so that			 * kbuild is not confused if a .c file is rewritten			 * into .S or vice versa. Storing it in source_* is			 * needed for modpost to compute srcversions.			 */			if (first) {				printf("source_%s := %s\n\n", target, s);				printf("deps_%s := \\\n", target);			} else				printf("  %s \\\n", s);			do_config_file(s);		}		first = 0;		m = p + 1;	}	printf("\n%s: $(deps_%s)\n\n", target, target);	printf("$(deps_%s):\n", target);} static void print_deps(void){	struct stat st;	int fd;	void *map; 	fd = open(depfile, O_RDONLY);	if (fd < 0) {		fprintf(stderr, "fixdep: error opening depfile: ");		perror(depfile);		exit(2);	}	if (fstat(fd, &st) < 0) {                fprintf(stderr, "fixdep: error fstat'ing depfile: ");                perror(depfile);                exit(2);        }	if (st.st_size == 0) {		fprintf(stderr,"fixdep: %s is empty\n",depfile);		close(fd);		return;	}	map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);	if ((long) map == -1) {		perror("fixdep: mmap");		close(fd);		return;	} 	parse_dep_file(map, st.st_size); 	munmap(map, st.st_size); 	close(fd);} static void traps(void){	static char test[] __attribute__((aligned(sizeof(int)))) = "CONF";	int *p = (int *)test; 	if (*p != INT_CONF) {		fprintf(stderr, "fixdep: sizeof(int) != 4 or wrong endianess? %#x\n",			*p);		exit(2);	}} int main(int argc, char *argv[]){	traps(); 	if (argc != 4)		usage(); 	depfile = argv[1];	target = argv[2];	cmdline = argv[3]; 	print_cmdline();	print_deps(); 	return 0;}