cregit-Linux how code gets into the kernel

Release 4.10 scripts/basic/fixdep.c

Directory: scripts/basic
 * "Optimize" a list of dependencies as spit out by gcc -MD
 * for the kernel build
 * ===========================================================================
 * Author       Kai Germaschewski
 * Copyright    2002 by Kai Germaschewski  <>
 * 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, <>.
 *   This is a C version of 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.
 * 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>

int insert_extra_deps;

char *target;

char *depfile;

char *cmdline;

static void usage(void) { fprintf(stderr, "Usage: fixdep [-e] <depfile> <target> <cmdline>\n"); fprintf(stderr, " -e insert extra dependencies given on stdin\n"); exit(1); }


kai germaschewskikai germaschewski1866.67%133.33%
nicolas pitrenicolas pitre829.63%133.33%
trevor keithtrevor keith13.70%133.33%

/* * Print out the commandline prefixed with cmd_<target filename> := */
static void print_cmdline(void) { printf("cmd_%s := %s\n\n", target, cmdline); }


kai germaschewskikai germaschewski1482.35%250.00%
jan beulichjan beulich211.76%125.00%
trevor keithtrevor keith15.88%125.00%

/* * Print out a dependency path from a symbol name */
static void print_config(const char *m, int slen) { int c, i; printf(" $(wildcard include/config/"); for (i = 0; i < slen; i++) { c = m[i]; if (c == '_') c = '/'; else c = tolower(c); putchar(c); } printf(".h) \\\n"); }


nicolas pitrenicolas pitre74100.00%1100.00%

static void do_extra_deps(void) { if (insert_extra_deps) { char buf[80]; while(fgets(buf, sizeof(buf), stdin)) { int len = strlen(buf); if (len < 2 || buf[len-1] != '\n') { fprintf(stderr, "fixdep: bad data on stdin\n"); exit(1); } print_config(buf, len-1); } } }


nicolas pitrenicolas pitre82100.00%1100.00%

struct item { struct item *next; unsigned int len; unsigned int hash; char name[0]; }; #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; }


eric dumazeteric dumazet4583.33%133.33%
kai germaschewskikai germaschewski814.81%133.33%
trevor keithtrevor keith11.85%133.33%

/* * 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; }


kai germaschewskikai germaschewski4457.14%133.33%
eric dumazeteric dumazet3241.56%133.33%
trevor keithtrevor keith11.30%133.33%

/* * 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; }


eric dumazeteric dumazet6164.89%133.33%
kai germaschewskikai germaschewski3234.04%133.33%
trevor keithtrevor keith11.06%133.33%

/* * 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_config(m, slen); }


kai germaschewskikai germaschewski3362.26%125.00%
eric dumazeteric dumazet1630.19%125.00%
nicolas pitrenicolas pitre35.66%125.00%
trevor keithtrevor keith11.89%125.00%

static void parse_config_file(const char *p) { const char *q, *r; while ((p = strstr(p, "CONFIG_"))) { p += 7; q = p; while (*q && (isalnum(*q) || *q == '_')) q++; if (memcmp(q - 7, "_MODULE", 7) == 0) r = q - 7; else r = q; if (r > p) use_config(p, r - p); p = q; } }


kai germaschewskikai germaschewski4945.37%225.00%
alexey dobriyanalexey dobriyan3229.63%112.50%
jan beulichjan beulich1614.81%112.50%
andy greenandy green43.70%112.50%
masahiro yamadamasahiro yamada43.70%112.50%
eric dumazeteric dumazet21.85%112.50%
trevor keithtrevor keith10.93%112.50%

/* test if s ends in sub */
static int strrcmp(const char *s, const char *sub) { int slen = strlen(s); int sublen = strlen(sub); if (sublen > slen) return 1; return memcmp(s + slen - sublen, sub, sublen); }


kai germaschewskikai germaschewski5294.55%133.33%
nicolas ioossnicolas iooss23.64%133.33%
trevor keithtrevor keith11.82%133.33%

static void do_config_file(const char *filename) { struct stat st; int fd; char *map; fd = open(filename, O_RDONLY); if (fd < 0) { fprintf(stderr, "fixdep: error opening config file: "); perror(filename); exit(2); } if (fstat(fd, &st) < 0) { fprintf(stderr, "fixdep: error fstat'ing config file: "); perror(filename); exit(2); } if (st.st_size == 0) { close(fd); return; } map = malloc(st.st_size + 1); if (!map) { perror("fixdep: malloc"); close(fd); return; } if (read(fd, map, st.st_size) != st.st_size) { perror("fixdep: read"); close(fd); return; } map[st.st_size] = '\0'; close(fd); parse_config_file(map); free(map); }


kai germaschewskikai germaschewski11963.98%337.50%
alexey dobriyanalexey dobriyan4122.04%112.50%
tom rinitom rini2312.37%112.50%
trevor keithtrevor keith10.54%112.50%
eric dumazeteric dumazet10.54%112.50%
ben gamariben gamari10.54%112.50%

/* * 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(void *map, size_t len) { char *m = map; char *end = m + len; char *p; char s[PATH_MAX]; int is_target; int saw_any_target = 0; int is_first_dep = 0; while (m < end) { /* Skip any "white space" */ while (m < end && (*m == ' ' || *m == '\\' || *m == '\n')) m++; /* Find next "white space" */ p = m; while (p < end && *p != ' ' && *p != '\\' && *p != '\n') p++; /* 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 { /* Save this token/filename */ memcpy(s, m, p-m); s[p - m] = 0; /* Ignore certain dependencies */ if (strrcmp(s, "include/generated/autoconf.h") && strrcmp(s, "include/generated/autoksyms.h") && strrcmp(s, "arch/um/include/uml-config.h") && strrcmp(s, "include/linux/kconfig.h") && strrcmp(s, ".ver")) { /* * 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; printf("source_%s := %s\n\n", target, s); printf("deps_%s := \\\n", target); } is_first_dep = 0; } else printf(" %s \\\n", s); do_config_file(s); } } /* * 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); } do_extra_deps(); printf("\n%s: $(deps_%s)\n\n", target, target); printf("$(deps_%s):\n", target); }


kai germaschewskikai germaschewski16655.15%323.08%
stephen warrenstephen warren8427.91%17.69%
michal marekmichal marek247.97%215.38%
nicolas pitrenicolas pitre103.32%215.38%
paolo giarrussopaolo giarrusso72.33%17.69%
peter foleypeter foley72.33%17.69%
sam ravnborgsam ravnborg20.66%215.38%
trevor keithtrevor keith10.33%17.69%

static void print_deps(void) { struct stat st; int fd; void *map; fd = open(depfile, O_RDONLY); if (fd < 0) { fprintf(stderr, "fixdep: error opening depfile: "); perror(depfile); exit(2); } if (fstat(fd, &st) < 0) { fprintf(stderr, "fixdep: error fstat'ing depfile: "); perror(depfile); exit(2); } 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); }


kai germaschewskikai germaschewski14985.63%466.67%
ben gamariben gamari2413.79%116.67%
trevor keithtrevor keith10.57%116.67%

int main(int argc, char *argv[]) { if (argc == 5 && !strcmp(argv[1], "-e")) { insert_extra_deps = 1; argv++; } else if (argc != 4) usage(); depfile = argv[1]; target = argv[2]; cmdline = argv[3]; print_cmdline(); print_deps(); return 0; }


kai germaschewskikai germaschewski5265.82%375.00%
nicolas pitrenicolas pitre2734.18%125.00%

Overall Contributors

kai germaschewskikai germaschewski79053.56%828.57%
nicolas pitrenicolas pitre20914.17%27.14%
eric dumazeteric dumazet18712.68%13.57%
stephen warrenstephen warren845.69%13.57%
alexey dobriyanalexey dobriyan745.02%13.57%
michal marekmichal marek251.69%27.14%
ben gamariben gamari251.69%13.57%
tom rinitom rini231.56%13.57%
jan beulichjan beulich191.29%27.14%
trevor keithtrevor keith110.75%13.57%
paolo giarrussopaolo giarrusso80.54%13.57%
peter foleypeter foley70.47%13.57%
masahiro yamadamasahiro yamada40.27%13.57%
andy greenandy green40.27%13.57%
sam ravnborgsam ravnborg30.20%310.71%
nicolas ioossnicolas iooss20.14%13.57%
Directory: scripts/basic
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