[1765] | 1 | /*
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| 2 | * "Optimize" a list of dependencies as spit out by gcc -MD
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| 3 | * for the kernel build
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| 4 | * ===========================================================================
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| 5 | *
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| 6 | * Author Kai Germaschewski
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| 7 | * Copyright 2002 by Kai Germaschewski <kai.germaschewski@gmx.de>
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| 8 | *
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| 9 | * This software may be used and distributed according to the terms
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| 10 | * of the GNU General Public License, incorporated herein by reference.
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| 11 | *
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| 12 | *
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| 13 | * Introduction:
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| 14 | *
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| 15 | * gcc produces a very nice and correct list of dependencies which
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| 16 | * tells make when to remake a file.
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| 17 | *
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| 18 | * To use this list as-is however has the drawback that virtually
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| 19 | * every file in the kernel includes <linux/config.h> which then again
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| 20 | * includes <linux/autoconf.h>
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| 21 | *
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| 22 | * If the user re-runs make *config, linux/autoconf.h will be
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| 23 | * regenerated. make notices that and will rebuild every file which
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| 24 | * includes autoconf.h, i.e. basically all files. This is extremely
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| 25 | * annoying if the user just changed CONFIG_HIS_DRIVER from n to m.
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| 26 | *
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| 27 | * So we play the same trick that "mkdep" played before. We replace
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| 28 | * the dependency on linux/autoconf.h by a dependency on every config
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| 29 | * option which is mentioned in any of the listed prequisites.
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| 30 | *
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| 31 | * To be exact, split-include populates a tree in include/config/,
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| 32 | * e.g. include/config/his/driver.h, which contains the #define/#undef
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| 33 | * for the CONFIG_HIS_DRIVER option.
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| 34 | *
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| 35 | * So if the user changes his CONFIG_HIS_DRIVER option, only the objects
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| 36 | * which depend on "include/linux/config/his/driver.h" will be rebuilt,
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| 37 | * so most likely only his driver ;-)
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| 38 | *
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| 39 | * The idea above dates, by the way, back to Michael E Chastain, AFAIK.
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| 40 | *
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| 41 | * So to get dependencies right, there are two issues:
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| 42 | * o if any of the files the compiler read changed, we need to rebuild
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| 43 | * o if the command line given to the compile the file changed, we
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| 44 | * better rebuild as well.
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| 45 | *
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| 46 | * The former is handled by using the -MD output, the later by saving
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| 47 | * the command line used to compile the old object and comparing it
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| 48 | * to the one we would now use.
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| 49 | *
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| 50 | * Again, also this idea is pretty old and has been discussed on
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| 51 | * kbuild-devel a long time ago. I don't have a sensibly working
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| 52 | * internet connection right now, so I rather don't mention names
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| 53 | * without double checking.
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| 54 | *
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| 55 | * This code here has been based partially based on mkdep.c, which
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| 56 | * says the following about its history:
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| 57 | *
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| 58 | * Copyright abandoned, Michael Chastain, <mailto:mec@shout.net>.
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| 59 | * This is a C version of syncdep.pl by Werner Almesberger.
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| 60 | *
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| 61 | *
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| 62 | * It is invoked as
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| 63 | *
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| 64 | * fixdep <depfile> <target> <cmdline>
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| 65 | *
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| 66 | * and will read the dependency file <depfile>
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| 67 | *
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| 68 | * The transformed dependency snipped is written to stdout.
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| 69 | *
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| 70 | * It first generates a line
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| 71 | *
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| 72 | * cmd_<target> = <cmdline>
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| 73 | *
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| 74 | * and then basically copies the .<target>.d file to stdout, in the
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| 75 | * process filtering out the dependency on linux/autoconf.h and adding
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| 76 | * dependencies on include/config/my/option.h for every
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| 77 | * CONFIG_MY_OPTION encountered in any of the prequisites.
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| 78 | *
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| 79 | * It will also filter out all the dependencies on *.ver. We need
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| 80 | * to make sure that the generated version checksum are globally up
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| 81 | * to date before even starting the recursive build, so it's too late
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| 82 | * at this point anyway.
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| 83 | *
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| 84 | * The algorithm to grep for "CONFIG_..." is bit unusual, but should
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| 85 | * be fast ;-) We don't even try to really parse the header files, but
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| 86 | * merely grep, i.e. if CONFIG_FOO is mentioned in a comment, it will
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| 87 | * be picked up as well. It's not a problem with respect to
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| 88 | * correctness, since that can only give too many dependencies, thus
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| 89 | * we cannot miss a rebuild. Since people tend to not mention totally
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| 90 | * unrelated CONFIG_ options all over the place, it's not an
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| 91 | * efficiency problem either.
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| 92 | *
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| 93 | * (Note: it'd be easy to port over the complete mkdep state machine,
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| 94 | * but I don't think the added complexity is worth it)
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| 95 | */
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| 96 | /*
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| 97 | * Note 2: if somebody writes HELLO_CONFIG_BOOM in a file, it will depend onto
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| 98 | * CONFIG_BOOM. This could seem a bug (not too hard to fix), but please do not
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| 99 | * fix it! Some UserModeLinux files (look at arch/um/) call CONFIG_BOOM as
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| 100 | * UML_CONFIG_BOOM, to avoid conflicts with /usr/include/linux/autoconf.h,
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| 101 | * through arch/um/include/uml-config.h; this fixdep "bug" makes sure that
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| 102 | * those files will have correct dependencies.
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| 103 | */
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| 104 |
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| 105 | #include <sys/types.h>
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| 106 | #include <sys/stat.h>
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| 107 | #include <sys/mman.h>
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| 108 | #include <unistd.h>
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| 109 | #include <fcntl.h>
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| 110 | #include <string.h>
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| 111 | #include <stdlib.h>
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| 112 | #include <stdio.h>
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| 113 | #include <limits.h>
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| 114 | #include <ctype.h>
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| 115 | #include <arpa/inet.h>
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| 116 |
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| 117 | /* bbox: not needed
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| 118 | #define INT_CONF ntohl(0x434f4e46)
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| 119 | #define INT_ONFI ntohl(0x4f4e4649)
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| 120 | #define INT_NFIG ntohl(0x4e464947)
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| 121 | #define INT_FIG_ ntohl(0x4649475f)
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| 122 | */
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| 123 |
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| 124 | char *target;
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| 125 | char *depfile;
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| 126 | char *cmdline;
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| 127 |
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| 128 | void usage(void)
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| 129 |
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| 130 | {
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| 131 | fprintf(stderr, "Usage: fixdep <depfile> <target> <cmdline>\n");
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| 132 | exit(1);
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| 133 | }
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| 134 |
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| 135 | /*
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| 136 | * Print out the commandline prefixed with cmd_<target filename> :=
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| 137 | */
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| 138 | void print_cmdline(void)
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| 139 | {
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| 140 | printf("cmd_%s := %s\n\n", target, cmdline);
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| 141 | }
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| 142 |
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| 143 | char * str_config = NULL;
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| 144 | int size_config = 0;
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| 145 | int len_config = 0;
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| 146 |
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| 147 | /*
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| 148 | * Grow the configuration string to a desired length.
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| 149 | * Usually the first growth is plenty.
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| 150 | */
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| 151 | void grow_config(int len)
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| 152 | {
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| 153 | while (len_config + len > size_config) {
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| 154 | if (size_config == 0)
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| 155 | size_config = 2048;
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| 156 | str_config = realloc(str_config, size_config *= 2);
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| 157 | if (str_config == NULL)
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| 158 | { perror("fixdep:malloc"); exit(1); }
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| 159 | }
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| 160 | }
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| 161 |
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| 162 |
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| 163 |
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| 164 | /*
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| 165 | * Lookup a value in the configuration string.
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| 166 | */
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| 167 | int is_defined_config(const char * name, int len)
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| 168 | {
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| 169 | const char * pconfig;
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| 170 | const char * plast = str_config + len_config - len;
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| 171 | for ( pconfig = str_config + 1; pconfig < plast; pconfig++ ) {
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| 172 | if (pconfig[ -1] == '\n'
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| 173 | && pconfig[len] == '\n'
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| 174 | && !memcmp(pconfig, name, len))
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| 175 | return 1;
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| 176 | }
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| 177 | return 0;
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| 178 | }
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| 179 |
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| 180 | /*
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| 181 | * Add a new value to the configuration string.
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| 182 | */
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| 183 | void define_config(const char * name, int len)
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| 184 | {
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| 185 | grow_config(len + 1);
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| 186 |
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| 187 | memcpy(str_config+len_config, name, len);
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| 188 | len_config += len;
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| 189 | str_config[len_config++] = '\n';
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| 190 | }
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| 191 |
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| 192 | /*
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| 193 | * Clear the set of configuration strings.
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| 194 | */
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| 195 | void clear_config(void)
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| 196 | {
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| 197 | len_config = 0;
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| 198 | define_config("", 0);
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| 199 | }
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| 200 |
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| 201 | /*
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| 202 | * Record the use of a CONFIG_* word.
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| 203 | */
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| 204 | void use_config(char *m, int slen)
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| 205 | {
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| 206 | char s[PATH_MAX];
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| 207 | char *p;
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| 208 |
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| 209 | if (is_defined_config(m, slen))
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| 210 | return;
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| 211 |
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| 212 | define_config(m, slen);
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| 213 |
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| 214 | memcpy(s, m, slen); s[slen] = 0;
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| 215 |
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| 216 | for (p = s; p < s + slen; p++) {
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| 217 | if (*p == '_')
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| 218 | *p = '/';
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| 219 | else
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| 220 | *p = tolower((int)*p);
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| 221 | }
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| 222 | printf(" $(wildcard include/config/%s.h) \\\n", s);
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| 223 | }
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| 224 |
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| 225 | void parse_config_file(char *map, size_t len)
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| 226 | {
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| 227 | /* modified for bbox */
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| 228 | char *end_4 = map + len - 4; /* 4 == length of "USE_" */
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| 229 | char *end_7 = map + len - 7;
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| 230 | char *p = map;
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| 231 | char *q;
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| 232 | int off;
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| 233 |
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| 234 | for (; p < end_4; p++) {
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| 235 | if (p < end_7 && p[6] == '_') {
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| 236 | if (!memcmp(p, "CONFIG", 6)) goto conf7;
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| 237 | if (!memcmp(p, "ENABLE", 6)) goto conf7;
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| 238 | }
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| 239 | /* We have at least 5 chars: for() has
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| 240 | * "p < end-4", not "p <= end-4"
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| 241 | * therefore we don't need to check p <= end-5 here */
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| 242 | if (p[4] == '_')
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| 243 | if (!memcmp(p, "SKIP", 4)) goto conf5;
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| 244 | /* Ehhh, gcc is too stupid to just compare it as 32bit int */
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| 245 | if (p[0] == 'U')
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| 246 | if (!memcmp(p, "USE_", 4)) goto conf4;
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| 247 | continue;
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| 248 |
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| 249 | conf4: off = 4;
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| 250 | conf5: off = 5;
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| 251 | conf7: off = 7;
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| 252 | p += off;
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| 253 | for (q = p; q < end_4+4; q++) {
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| 254 | if (!(isalnum(*q) || *q == '_'))
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| 255 | break;
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| 256 | }
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| 257 | use_config(p, q-p);
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| 258 | }
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| 259 | }
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| 260 |
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| 261 | /* test is s ends in sub */
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| 262 | int strrcmp(char *s, char *sub)
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| 263 | {
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| 264 | int slen = strlen(s);
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| 265 | int sublen = strlen(sub);
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| 266 |
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| 267 | if (sublen > slen)
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| 268 | return 1;
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| 269 |
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| 270 | return memcmp(s + slen - sublen, sub, sublen);
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| 271 | }
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| 272 |
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| 273 | void do_config_file(char *filename)
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| 274 | {
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| 275 | struct stat st;
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| 276 | int fd;
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| 277 | void *map;
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| 278 |
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| 279 | fd = open(filename, O_RDONLY);
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| 280 | if (fd < 0) {
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| 281 | fprintf(stderr, "fixdep: ");
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| 282 | perror(filename);
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| 283 | exit(2);
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| 284 | }
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| 285 | fstat(fd, &st);
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| 286 | if (st.st_size == 0) {
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| 287 | close(fd);
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| 288 | return;
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| 289 | }
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| 290 | map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
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| 291 | if ((long) map == -1) {
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| 292 | perror("fixdep: mmap");
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| 293 | close(fd);
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| 294 | return;
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| 295 | }
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| 296 |
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| 297 | parse_config_file(map, st.st_size);
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| 298 |
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| 299 | munmap(map, st.st_size);
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| 300 |
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| 301 | close(fd);
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| 302 | }
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| 303 |
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| 304 | void parse_dep_file(void *map, size_t len)
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| 305 | {
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| 306 | char *m = map;
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| 307 | char *end = m + len;
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| 308 | char *p;
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| 309 | char s[PATH_MAX];
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| 310 |
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| 311 | p = memchr(m, ':', len);
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| 312 | if (!p) {
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| 313 | fprintf(stderr, "fixdep: parse error\n");
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| 314 | exit(1);
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| 315 | }
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| 316 | memcpy(s, m, p-m); s[p-m] = 0;
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| 317 | printf("deps_%s := \\\n", target);
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| 318 | m = p+1;
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| 319 |
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| 320 | clear_config();
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| 321 |
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| 322 | while (m < end) {
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| 323 | while (m < end && (*m == ' ' || *m == '\\' || *m == '\n'))
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| 324 | m++;
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| 325 | p = m;
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| 326 | while (p < end && *p != ' ') p++;
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| 327 | if (p == end) {
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| 328 | do p--; while (!isalnum(*p));
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| 329 | p++;
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| 330 | }
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| 331 | memcpy(s, m, p-m); s[p-m] = 0;
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| 332 | if (strrcmp(s, "include/autoconf.h") &&
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| 333 | strrcmp(s, "arch/um/include/uml-config.h") &&
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| 334 | strrcmp(s, ".ver")) {
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| 335 | printf(" %s \\\n", s);
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| 336 | do_config_file(s);
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| 337 | }
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| 338 | m = p + 1;
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| 339 | }
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| 340 | printf("\n%s: $(deps_%s)\n\n", target, target);
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| 341 | printf("$(deps_%s):\n", target);
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| 342 | }
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| 343 |
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| 344 | void print_deps(void)
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| 345 | {
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| 346 | struct stat st;
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| 347 | int fd;
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| 348 | void *map;
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| 349 |
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| 350 | fd = open(depfile, O_RDONLY);
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| 351 | if (fd < 0) {
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| 352 | fprintf(stderr, "fixdep: ");
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| 353 | perror(depfile);
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| 354 | exit(2);
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| 355 | }
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| 356 | fstat(fd, &st);
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| 357 | if (st.st_size == 0) {
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| 358 | fprintf(stderr,"fixdep: %s is empty\n",depfile);
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| 359 | close(fd);
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| 360 | return;
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| 361 | }
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| 362 | map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
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| 363 | if ((long) map == -1) {
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| 364 | perror("fixdep: mmap");
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| 365 | close(fd);
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| 366 | return;
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| 367 | }
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| 368 |
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| 369 | parse_dep_file(map, st.st_size);
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| 370 |
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| 371 | munmap(map, st.st_size);
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| 372 |
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| 373 | close(fd);
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| 374 | }
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| 375 |
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| 376 | void traps(void)
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| 377 | {
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| 378 | /* bbox: not needed
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| 379 | static char test[] __attribute__((aligned(sizeof(int)))) = "CONF";
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| 380 |
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| 381 | if (*(int *)test != INT_CONF) {
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| 382 | fprintf(stderr, "fixdep: sizeof(int) != 4 or wrong endianess? %#x\n",
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| 383 | *(int *)test);
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| 384 | exit(2);
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| 385 | }
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| 386 | */
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| 387 | }
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| 388 |
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| 389 | int main(int argc, char **argv)
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| 390 | {
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| 391 | traps();
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| 392 |
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| 393 | if (argc != 4)
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| 394 | usage();
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| 395 |
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| 396 | depfile = argv[1];
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| 397 | target = argv[2];
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| 398 | cmdline = argv[3];
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| 399 |
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| 400 | print_cmdline();
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| 401 | print_deps();
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| 402 |
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| 403 | return 0;
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| 404 | }
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