scripts/basic/fixdep.c - linux - Git at Google

 /*
  * "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
  *
  *   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 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 <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() 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);
 }

 struct item {
 	struct item	*next;
 	unsigned int	len;
 	unsigned int	hash;
 	char		name[];
 };

 #define HASHSZ 256
 static 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 out a dependency path from a symbol name. */
 	xprintf("    $(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") ||
 	       str_ends_with(s, len, "include/generated/autoksyms.h");
 }

 /*
  * 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;
 }
	/*
	* "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
	*
	* 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 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 <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() 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);
	}

	struct item {
	struct item *next;
	unsigned int len;
	unsigned int hash;
	char name[];
	};

	#define HASHSZ 256
	static 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 out a dependency path from a symbol name. */
	xprintf(" $(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") \|\|
	str_ends_with(s, len, "include/generated/autoksyms.h");
	}

	/*
	* 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;
	}