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fixdep.c

/* * "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 256 static 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; }

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docroot: /var/www/469ed2f6-4d4b-4a8a-9f5e-ee4ef04d3bc8/public_html

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curdir: /usr/src/linux-headers-6.8.0-117-generic/scripts/basic

	.		4096
	..		12288
X	Makefile		629
X	fixdep		17024
X	fixdep.c		10934