/* * "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.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 prerequisites. * * 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. * * 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 <stdarg.h>#include <stdlib.h>#include <stdio.h>#include <ctype.h> static void usage(void){	fprintf(stderr, "Usage: fixdep <depfile> <target> <cmdline>\n");	exit(1);} /* * In the intended usage of this program, the stdout is redirected to .*.cmd * files. The return value of printf() and putchar() must be checked to catch * any error, e.g. "No space left on device". */static void xprintf(const char *format, ...){	va_list ap;	int ret; 	va_start(ap, format);	ret = vprintf(format, ap);	if (ret < 0) {		perror("fixdep");		exit(1);	}	va_end(ap);} static void xputchar(int c){	int ret; 	ret = putchar(c);	if (ret == EOF) {		perror("fixdep");		exit(1);	}} /* * Print out a dependency path from a symbol name */static void print_dep(const char *m, int slen, const char *dir){	int c, prev_c = '/', i; 	xprintf("    $(wildcard %s/", dir);	for (i = 0; i < slen; i++) {		c = m[i];		if (c == '_')			c = '/';		else			c = tolower(c);		if (c != '/' || prev_c != '/')			xputchar(c);		prev_c = c;	}	xprintf(".h) \\\n");} 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;} /* * Record the use of a CONFIG_* word. */static void use_config(const char *m, int slen){	unsigned int hash = strhash(m, slen); 	if (is_defined_config(m, slen, hash))	    return; 	define_config(m, slen, hash);	print_dep(m, slen, "include/config");} /* 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 (*q && (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") ||	       str_ends_with(s, len, "include/generated/autoksyms.h") ||	       str_ends_with(s, len, ".ver");} /* * 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 *m, const char *target){	char *p;	int is_last, is_target;	int saw_any_target = 0;	int is_first_dep = 0;	void *buf; 	while (1) {		/* Skip any "white space" */		while (*m == ' ' || *m == '\\' || *m == '\n')			m++; 		if (!*m)			break; 		/* Find next "white space" */		p = m;		while (*p && *p != ' ' && *p != '\\' && *p != '\n')			p++;		is_last = (*p == '\0');		/* Is the token we found a target name? */		is_target = (*(p-1) == ':');		/* Don't write any target names into the dependency file */		if (is_target) {			/* The /next/ file is the first dependency */			is_first_dep = 1;		} else if (!is_ignored_file(m, p - m)) {			*p = '\0'; 			/*			 * 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_first_dep) {				/*				 * If processing the concatenation of multiple				 * dependency files, only process the first				 * target name, which will be the original				 * source name, and ignore any other target				 * names, which will be intermediate temporary				 * files.				 */				if (!saw_any_target) {					saw_any_target = 1;					xprintf("source_%s := %s\n\n",						target, m);					xprintf("deps_%s := \\\n", target);				}				is_first_dep = 0;			} else {				xprintf("  %s \\\n", m);			} 			buf = read_file(m);			parse_config_file(buf);			free(buf);		} 		if (is_last)			break; 		/*		 * Start searching for next token immediately after the first		 * "whitespace" character that follows this token.		 */		m = p + 1;	} 	if (!saw_any_target) {		fprintf(stderr, "fixdep: parse error; no targets found\n");		exit(1);	} 	xprintf("\n%s: $(deps_%s)\n\n", target, target);	xprintf("$(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]; 	xprintf("cmd_%s := %s\n\n", target, cmdline); 	buf = read_file(depfile);	parse_dep_file(buf, target);	free(buf); 	return 0;}