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404 lines
9.6 KiB
404 lines
9.6 KiB
/* |
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* "Optimize" a list of dependencies as spit out by gcc -MD |
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* for the kernel build |
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* =========================================================================== |
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* |
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* Author Kai Germaschewski |
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* Copyright 2002 by Kai Germaschewski <[email protected]> |
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* |
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* This software may be used and distributed according to the terms |
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* of the GNU General Public License, incorporated herein by reference. |
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* |
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* |
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* Introduction: |
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* |
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* gcc produces a very nice and correct list of dependencies which |
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* tells make when to remake a file. |
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* |
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* To use this list as-is however has the drawback that virtually |
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* every file in the kernel includes autoconf.h. |
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* |
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* If the user re-runs make *config, autoconf.h will be |
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* regenerated. make notices that and will rebuild every file which |
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* includes autoconf.h, i.e. basically all files. This is extremely |
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* annoying if the user just changed CONFIG_HIS_DRIVER from n to m. |
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* |
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* So we play the same trick that "mkdep" played before. We replace |
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* the dependency on autoconf.h by a dependency on every config |
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* option which is mentioned in any of the listed prerequisites. |
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* |
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* kconfig populates a tree in include/config/ with an empty file |
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* for each config symbol and when the configuration is updated |
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* the files representing changed config options are touched |
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* which then let make pick up the changes and the files that use |
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* the config symbols are rebuilt. |
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* |
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* So if the user changes his CONFIG_HIS_DRIVER option, only the objects |
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* which depend on "include/config/his/driver.h" will be rebuilt, |
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* so most likely only his driver ;-) |
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* |
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* The idea above dates, by the way, back to Michael E Chastain, AFAIK. |
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* |
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* So to get dependencies right, there are two issues: |
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* o if any of the files the compiler read changed, we need to rebuild |
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* o if the command line given to the compile the file changed, we |
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* better rebuild as well. |
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* |
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* The former is handled by using the -MD output, the later by saving |
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* the command line used to compile the old object and comparing it |
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* to the one we would now use. |
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* |
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* Again, also this idea is pretty old and has been discussed on |
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* kbuild-devel a long time ago. I don't have a sensibly working |
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* internet connection right now, so I rather don't mention names |
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* without double checking. |
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* |
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* This code here has been based partially based on mkdep.c, which |
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* says the following about its history: |
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* |
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* Copyright abandoned, Michael Chastain, <mailto:[email protected]>. |
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* This is a C version of syncdep.pl by Werner Almesberger. |
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* |
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* |
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* It is invoked as |
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* |
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* fixdep <depfile> <target> <cmdline> |
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* |
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* and will read the dependency file <depfile> |
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* |
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* The transformed dependency snipped is written to stdout. |
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* |
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* It first generates a line |
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* |
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* cmd_<target> = <cmdline> |
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* |
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* and then basically copies the .<target>.d file to stdout, in the |
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* process filtering out the dependency on autoconf.h and adding |
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* dependencies on include/config/my/option.h for every |
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* CONFIG_MY_OPTION encountered in any of the prerequisites. |
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* |
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* We don't even try to really parse the header files, but |
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* merely grep, i.e. if CONFIG_FOO is mentioned in a comment, it will |
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* be picked up as well. It's not a problem with respect to |
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* correctness, since that can only give too many dependencies, thus |
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* we cannot miss a rebuild. Since people tend to not mention totally |
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* unrelated CONFIG_ options all over the place, it's not an |
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* efficiency problem either. |
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* |
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* (Note: it'd be easy to port over the complete mkdep state machine, |
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* but I don't think the added complexity is worth it) |
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*/ |
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#include <sys/types.h> |
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#include <sys/stat.h> |
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#include <unistd.h> |
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#include <fcntl.h> |
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#include <string.h> |
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#include <stdarg.h> |
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#include <stdlib.h> |
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#include <stdio.h> |
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#include <ctype.h> |
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static void usage(void) |
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{ |
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fprintf(stderr, "Usage: fixdep <depfile> <target> <cmdline>\n"); |
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exit(1); |
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} |
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/* |
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* In the intended usage of this program, the stdout is redirected to .*.cmd |
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* files. The return value of printf() and putchar() must be checked to catch |
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* any error, e.g. "No space left on device". |
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*/ |
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static void xprintf(const char *format, ...) |
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{ |
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va_list ap; |
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int ret; |
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va_start(ap, format); |
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ret = vprintf(format, ap); |
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if (ret < 0) { |
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perror("fixdep"); |
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exit(1); |
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} |
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va_end(ap); |
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} |
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static void xputchar(int c) |
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{ |
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int ret; |
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ret = putchar(c); |
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if (ret == EOF) { |
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perror("fixdep"); |
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exit(1); |
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} |
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} |
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/* |
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* Print out a dependency path from a symbol name |
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*/ |
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static void print_dep(const char *m, int slen, const char *dir) |
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{ |
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int c, prev_c = '/', i; |
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xprintf(" $(wildcard %s/", dir); |
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for (i = 0; i < slen; i++) { |
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c = m[i]; |
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if (c == '_') |
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c = '/'; |
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else |
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c = tolower(c); |
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if (c != '/' || prev_c != '/') |
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xputchar(c); |
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prev_c = c; |
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} |
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xprintf(".h) \\\n"); |
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} |
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struct item { |
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struct item *next; |
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unsigned int len; |
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unsigned int hash; |
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char name[]; |
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}; |
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#define HASHSZ 256 |
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static struct item *hashtab[HASHSZ]; |
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static unsigned int strhash(const char *str, unsigned int sz) |
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{ |
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/* fnv32 hash */ |
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unsigned int i, hash = 2166136261U; |
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for (i = 0; i < sz; i++) |
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hash = (hash ^ str[i]) * 0x01000193; |
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return hash; |
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} |
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/* |
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* Lookup a value in the configuration string. |
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*/ |
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static int is_defined_config(const char *name, int len, unsigned int hash) |
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{ |
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struct item *aux; |
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for (aux = hashtab[hash % HASHSZ]; aux; aux = aux->next) { |
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if (aux->hash == hash && aux->len == len && |
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memcmp(aux->name, name, len) == 0) |
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return 1; |
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} |
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return 0; |
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} |
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/* |
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* Add a new value to the configuration string. |
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*/ |
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static void define_config(const char *name, int len, unsigned int hash) |
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{ |
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struct item *aux = malloc(sizeof(*aux) + len); |
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if (!aux) { |
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perror("fixdep:malloc"); |
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exit(1); |
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} |
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memcpy(aux->name, name, len); |
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aux->len = len; |
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aux->hash = hash; |
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aux->next = hashtab[hash % HASHSZ]; |
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hashtab[hash % HASHSZ] = aux; |
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} |
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/* |
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* Record the use of a CONFIG_* word. |
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*/ |
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static void use_config(const char *m, int slen) |
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{ |
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unsigned int hash = strhash(m, slen); |
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if (is_defined_config(m, slen, hash)) |
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return; |
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define_config(m, slen, hash); |
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print_dep(m, slen, "include/config"); |
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} |
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/* test if s ends in sub */ |
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static int str_ends_with(const char *s, int slen, const char *sub) |
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{ |
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int sublen = strlen(sub); |
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if (sublen > slen) |
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return 0; |
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return !memcmp(s + slen - sublen, sub, sublen); |
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} |
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static void parse_config_file(const char *p) |
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{ |
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const char *q, *r; |
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const char *start = p; |
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while ((p = strstr(p, "CONFIG_"))) { |
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if (p > start && (isalnum(p[-1]) || p[-1] == '_')) { |
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p += 7; |
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continue; |
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} |
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p += 7; |
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q = p; |
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while (isalnum(*q) || *q == '_') |
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q++; |
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if (str_ends_with(p, q - p, "_MODULE")) |
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r = q - 7; |
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else |
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r = q; |
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if (r > p) |
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use_config(p, r - p); |
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p = q; |
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} |
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} |
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static void *read_file(const char *filename) |
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{ |
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struct stat st; |
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int fd; |
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char *buf; |
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fd = open(filename, O_RDONLY); |
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if (fd < 0) { |
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fprintf(stderr, "fixdep: error opening file: "); |
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perror(filename); |
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exit(2); |
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} |
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if (fstat(fd, &st) < 0) { |
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fprintf(stderr, "fixdep: error fstat'ing file: "); |
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perror(filename); |
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exit(2); |
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} |
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buf = malloc(st.st_size + 1); |
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if (!buf) { |
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perror("fixdep: malloc"); |
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exit(2); |
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} |
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if (read(fd, buf, st.st_size) != st.st_size) { |
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perror("fixdep: read"); |
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exit(2); |
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} |
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buf[st.st_size] = '\0'; |
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close(fd); |
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return buf; |
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} |
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/* Ignore certain dependencies */ |
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static int is_ignored_file(const char *s, int len) |
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{ |
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return str_ends_with(s, len, "include/generated/autoconf.h") || |
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str_ends_with(s, len, "include/generated/autoksyms.h"); |
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} |
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/* |
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* Important: The below generated source_foo.o and deps_foo.o variable |
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* assignments are parsed not only by make, but also by the rather simple |
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* parser in scripts/mod/sumversion.c. |
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*/ |
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static void parse_dep_file(char *m, const char *target) |
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{ |
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char *p; |
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int is_last, is_target; |
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int saw_any_target = 0; |
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int is_first_dep = 0; |
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void *buf; |
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while (1) { |
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/* Skip any "white space" */ |
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while (*m == ' ' || *m == '\\' || *m == '\n') |
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m++; |
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if (!*m) |
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break; |
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/* Find next "white space" */ |
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p = m; |
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while (*p && *p != ' ' && *p != '\\' && *p != '\n') |
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p++; |
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is_last = (*p == '\0'); |
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/* Is the token we found a target name? */ |
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is_target = (*(p-1) == ':'); |
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/* Don't write any target names into the dependency file */ |
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if (is_target) { |
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/* The /next/ file is the first dependency */ |
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is_first_dep = 1; |
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} else if (!is_ignored_file(m, p - m)) { |
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*p = '\0'; |
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/* |
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* Do not list the source file as dependency, so that |
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* kbuild is not confused if a .c file is rewritten |
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* into .S or vice versa. Storing it in source_* is |
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* needed for modpost to compute srcversions. |
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*/ |
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if (is_first_dep) { |
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/* |
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* If processing the concatenation of multiple |
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* dependency files, only process the first |
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* target name, which will be the original |
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* source name, and ignore any other target |
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* names, which will be intermediate temporary |
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* files. |
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*/ |
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if (!saw_any_target) { |
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saw_any_target = 1; |
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xprintf("source_%s := %s\n\n", |
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target, m); |
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xprintf("deps_%s := \\\n", target); |
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} |
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is_first_dep = 0; |
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} else { |
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xprintf(" %s \\\n", m); |
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} |
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buf = read_file(m); |
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parse_config_file(buf); |
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free(buf); |
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} |
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if (is_last) |
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break; |
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/* |
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* Start searching for next token immediately after the first |
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* "whitespace" character that follows this token. |
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*/ |
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m = p + 1; |
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} |
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if (!saw_any_target) { |
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fprintf(stderr, "fixdep: parse error; no targets found\n"); |
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exit(1); |
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} |
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xprintf("\n%s: $(deps_%s)\n\n", target, target); |
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xprintf("$(deps_%s):\n", target); |
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} |
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int main(int argc, char *argv[]) |
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{ |
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const char *depfile, *target, *cmdline; |
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void *buf; |
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if (argc != 4) |
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usage(); |
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depfile = argv[1]; |
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target = argv[2]; |
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cmdline = argv[3]; |
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xprintf("cmd_%s := %s\n\n", target, cmdline); |
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buf = read_file(depfile); |
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parse_dep_file(buf, target); |
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free(buf); |
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return 0; |
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}
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