[Minios-devel] [UNIKRAFT PATCH v3 2/5] build: import fixdep.c from linux kernel

[Yuri Volchkov <yuri.volchkov@xxxxxxxxx>]

For the sake of trace-ability, the file is imported _AS_IS_ without a
single modification.

Originaly placed scripts/basic/fixdep.c

Git tag 4.17-rc1,
commit Linux 4.17-rc1 (60cc43fc888428bb2f18f08997432d426a243338)

Signed-off-by: Yuri Volchkov <yuri.volchkov@xxxxxxxxx>
Reviewed-by: Simon Kuenzer <simon.kuenzer@xxxxxxxxx>
---
 support/kconfig/fixdep.c | 404 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 404 insertions(+)
 create mode 100644 support/kconfig/fixdep.c

diff --git a/support/kconfig/fixdep.c b/support/kconfig/fixdep.c
new file mode 100644
index 0000000..beeb52b
--- /dev/null
+++ b/support/kconfig/fixdep.c
@@ -0,0 +1,404 @@
+/*
+ * "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@xxxxxx>
+ *
+ * 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.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@xxxxxxxxx>.
+ *   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 prerequisites.
+ *
+ * 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)
+ *
+ * This source is copied from linux kernel
+ * (scripts/basic/fixdep.c). Tag 4.17-rc1, commit
+ * 60cc43fc888428bb2f18f08997432d426a243338
+ */
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <string.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <ctype.h>
+
+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);
+}
+
+/*
+ * Print out a dependency path from a symbol name
+ */
+static void print_dep(const char *m, int slen, const char *dir)
+{
+       int c, i;
+
+       printf("    $(wildcard %s/", dir);
+       for (i = 0; i < slen; i++) {
+               c = m[i];
+               if (c == '_')
+                       c = '/';
+               else
+                       c = tolower(c);
+               putchar(c);
+       }
+       printf(".h) \\\n");
+}
+
+static void do_extra_deps(void)
+{
+       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_dep(buf, len - 1, "include/ksym");
+       }
+}
+
+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;
+}
+
+/*
+ * 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_dep(m, slen, "include/config");
+}
+
+/* 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 (*q && (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") ||
+              str_ends_with(s, len, ".ver");
+}
+
+/*
+ * 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, int insert_extra_deps)
+{
+       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;
+                                       printf("source_%s := %s\n\n",
+                                              target, m);
+                                       printf("deps_%s := \\\n", target);
+                               }
+                               is_first_dep = 0;
+                       } else {
+                               printf("  %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);
+       }
+
+       if (insert_extra_deps)
+               do_extra_deps();
+
+       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;
+       int insert_extra_deps = 0;
+       void *buf;
+
+       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];
+
+       printf("cmd_%s := %s\n\n", target, cmdline);
+
+       buf = read_file(depfile);
+       parse_dep_file(buf, target, insert_extra_deps);
+       free(buf);
+
+       return 0;
+}
-- 
2.17.0


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