/* * "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 prerequisites. * * 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/config/HIS_DRIVER" 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 * *   savedcmd_<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 for every * CONFIG_MY_OPTION encountered in any of the prerequisites. * * 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) */ #include <sys/types.h>#include <sys/stat.h>#include <unistd.h>#include <fcntl.h>#include <string.h>#include <stdbool.h>#include <stdlib.h>#include <stdio.h>#include <ctype.h> static void usage(void){	fprintf(stderr, "Usage: fixdep <depfile> <target> <cmdline>\n");	exit(1);} struct item {	struct item	*next;	unsigned int	len;	unsigned int	hash;	char		name[];}; #define HASHSZ 256static struct item *config_hashtab[HASHSZ], *file_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;} /* * Add a new value to the configuration string. */static void add_to_hashtable(const char *name, int len, unsigned int hash,			     struct item *hashtab[]){	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;} /* * Lookup a string in the hash table. If found, just return true. * If not, add it to the hashtable and return false. */static bool in_hashtable(const char *name, int len, struct item *hashtab[]){	struct item *aux;	unsigned int hash = strhash(name, len); 	for (aux = hashtab[hash % HASHSZ]; aux; aux = aux->next) {		if (aux->hash == hash && aux->len == len &&		    memcmp(aux->name, name, len) == 0)			return true;	} 	add_to_hashtable(name, len, hash, hashtab); 	return false;} /* * Record the use of a CONFIG_* word. */static void use_config(const char *m, int slen){	if (in_hashtable(m, slen, config_hashtab))		return; 	/* Print out a dependency path from a symbol name. */	printf("    $(wildcard include/config/%.*s) \\\n", slen, m);} /* test if s ends in sub */static int str_ends_with(const char *s, int slen, const char *sub){	int sublen = strlen(sub); 	if (sublen > slen)		return 0; 	return !memcmp(s + slen - sublen, sub, sublen);} static void parse_config_file(const char *p){	const char *q, *r;	const char *start = p; 	while ((p = strstr(p, "CONFIG_"))) {		if (p > start && (isalnum(p[-1]) || p[-1] == '_')) {			p += 7;			continue;		}		p += 7;		q = p;		while (isalnum(*q) || *q == '_')			q++;		if (str_ends_with(p, q - p, "_MODULE"))			r = q - 7;		else			r = q;		if (r > p)			use_config(p, r - p);		p = q;	}} static void *read_file(const char *filename){	struct stat st;	int fd;	char *buf; 	fd = open(filename, O_RDONLY);	if (fd < 0) {		fprintf(stderr, "fixdep: error opening file: ");		perror(filename);		exit(2);	}	if (fstat(fd, &st) < 0) {		fprintf(stderr, "fixdep: error fstat'ing file: ");		perror(filename);		exit(2);	}	buf = malloc(st.st_size + 1);	if (!buf) {		perror("fixdep: malloc");		exit(2);	}	if (read(fd, buf, st.st_size) != st.st_size) {		perror("fixdep: read");		exit(2);	}	buf[st.st_size] = '\0';	close(fd); 	return buf;} /* Ignore certain dependencies */static int is_ignored_file(const char *s, int len){	return str_ends_with(s, len, "include/generated/autoconf.h");} /* Do not parse these files */static int is_no_parse_file(const char *s, int len){	/* rustc may list binary files in dep-info */	return str_ends_with(s, len, ".rlib") ||	       str_ends_with(s, len, ".rmeta") ||	       str_ends_with(s, len, ".so");} /* * 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(char *p, const char *target){	bool saw_any_target = false;	bool is_target = true;	bool is_source = false;	bool need_parse;	char *q, saved_c; 	while (*p) {		/* handle some special characters first. */		switch (*p) {		case '#':			/*			 * skip comments.			 * rustc may emit comments to dep-info.			 */			p++;			while (*p != '\0' && *p != '\n') {				/*				 * escaped newlines continue the comment across				 * multiple lines.				 */				if (*p == '\\')					p++;				p++;			}			continue;		case ' ':		case '\t':			/* skip whitespaces */			p++;			continue;		case '\\':			/*			 * backslash/newline combinations continue the			 * statement. Skip it just like a whitespace.			 */			if (*(p + 1) == '\n') {				p += 2;				continue;			}			break;		case '\n':			/*			 * Makefiles use a line-based syntax, where the newline			 * is the end of a statement. After seeing a newline,			 * we expect the next token is a target.			 */			p++;			is_target = true;			continue;		case ':':			/*			 * assume the first dependency after a colon as the			 * source file.			 */			p++;			is_target = false;			is_source = true;			continue;		} 		/* find the end of the token */		q = p;		while (*q != ' ' && *q != '\t' && *q != '\n' && *q != '#' && *q != ':') {			if (*q == '\\') {				/*				 * backslash/newline combinations work like as				 * a whitespace, so this is the end of token.				 */				if (*(q + 1) == '\n')					break; 				/* escaped special characters */				if (*(q + 1) == '#' || *(q + 1) == ':') {					memmove(p + 1, p, q - p);					p++;				} 				q++;			} 			if (*q == '\0')				break;			q++;		} 		/* Just discard the target */		if (is_target) {			p = q;			continue;		} 		saved_c = *q;		*q = '\0';		need_parse = false; 		/*		 * 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 (is_source) {			/*			 * The DT build rule concatenates multiple dep files.			 * When processing them, only process the first source			 * name, which will be the original one, and ignore any			 * other source names, which will be intermediate			 * temporary files.			 *			 * rustc emits the same dependency list for each			 * emission type. It is enough to list the source name			 * just once.			 */			if (!saw_any_target) {				saw_any_target = true;				printf("source_%s := %s\n\n", target, p);				printf("deps_%s := \\\n", target);				need_parse = true;			}		} else if (!is_ignored_file(p, q - p) &&			   !in_hashtable(p, q - p, file_hashtab)) {			printf("  %s \\\n", p);			need_parse = true;		} 		if (need_parse && !is_no_parse_file(p, q - p)) {			void *buf; 			buf = read_file(p);			parse_config_file(buf);			free(buf);		} 		is_source = false;		*q = saved_c;		p = q;	} 	if (!saw_any_target) {		fprintf(stderr, "fixdep: parse error; no targets found\n");		exit(1);	} 	printf("\n%s: $(deps_%s)\n\n", target, target);	printf("$(deps_%s):\n", target);} int main(int argc, char *argv[]){	const char *depfile, *target, *cmdline;	void *buf; 	if (argc != 4)		usage(); 	depfile = argv[1];	target = argv[2];	cmdline = argv[3]; 	printf("savedcmd_%s := %s\n\n", target, cmdline); 	buf = read_file(depfile);	parse_dep_file(buf, target);	free(buf); 	fflush(stdout); 	/*	 * In the intended usage, the stdout is redirected to .*.cmd files.	 * Call ferror() to catch errors such as "No space left on device".	 */	if (ferror(stdout)) {		fprintf(stderr, "fixdep: not all data was written to the output\n");		exit(1);	} 	return 0;}