/* * "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); } char * str_config = NULL; int size_config = 0; int len_config = 0; /* * Grow the configuration string to a desired length. * Usually the first growth is plenty. */ static void grow_config(int len) { while (len_config + len > size_config) { if (size_config == 0) size_config = 2048; str_config = realloc(str_config, size_config *= 2); if (str_config == NULL) { perror("fixdep:malloc"); exit(1); } } } /* * Lookup a value in the configuration string. */ static int is_defined_config(const char * name, int len) { const char * pconfig; const char * plast = str_config + len_config - len; for ( pconfig = str_config + 1; pconfig < plast; pconfig++ ) { if (pconfig[ -1] == '\n' && pconfig[len] == '\n' && !memcmp(pconfig, name, len)) return 1; } return 0; } /* * Add a new value to the configuration string. */ static void define_config(const char * name, int len) { grow_config(len + 1); memcpy(str_config+len_config, name, len); len_config += len; str_config[len_config++] = '\n'; } /* * Clear the set of configuration strings. */ static void clear_config(void) { len_config = 0; define_config("", 0); } /* * Record the use of a CONFIG_* word. */ static void use_config(char *m, int slen) { char s[PATH_MAX]; char *p; if (is_defined_config(m, slen)) return; define_config(m, slen); memcpy(s, m, slen); s[slen] = 0; for (p = s; p < s + slen; p++) { if (*p == '_') *p = '/'; else *p = tolower((int)*p); } printf(" $(wildcard include/config/%s.h) \\\n", s); } static void parse_config_file(char *map, size_t len) { int *end = (int *) (map + len); /* start at +1, so that p can never be < map */ int *m = (int *) map + 1; 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(char *filename) { struct stat st; int fd; void *map; fd = open(filename, O_RDONLY); if (fd < 0) { fprintf(stderr, "fixdep: "); 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); } static void parse_dep_file(void *map, size_t len) { char *m = map; char *end = m + len; char *p; char s[PATH_MAX]; p = strchr(m, ':'); if (!p) { fprintf(stderr, "fixdep: parse error\n"); exit(1); } memcpy(s, m, p-m); s[p-m] = 0; printf("deps_%s := \\\n", target); m = p+1; clear_config(); 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, ".ver")) { printf(" %s \\\n", s); do_config_file(s); } 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: "); perror(depfile); exit(2); } fstat(fd, &st); 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; }