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 | #include <alloca.h>
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117 |
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118 | /* bbox: not needed
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119 | #define INT_CONF ntohl(0x434f4e46)
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120 | #define INT_ONFI ntohl(0x4f4e4649)
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121 | #define INT_NFIG ntohl(0x4e464947)
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122 | #define INT_FIG_ ntohl(0x4649475f)
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123 | */
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124 |
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125 | char *target;
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126 | char *depfile;
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127 | char *cmdline;
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128 |
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129 | void usage(void)
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130 |
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131 | {
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132 | fprintf(stderr, "Usage: fixdep <depfile> <target> <cmdline>\n");
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133 | exit(1);
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134 | }
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135 |
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136 | /*
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137 | * Print out the commandline prefixed with cmd_<target filename> :=
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138 | */
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139 | void print_cmdline(void)
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140 | {
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141 | printf("cmd_%s := %s\n\n", target, cmdline);
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142 | }
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143 |
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144 | char * str_config = NULL;
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145 | int size_config = 0;
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146 | int len_config = 0;
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147 |
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148 | /*
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149 | * Grow the configuration string to a desired length.
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150 | * Usually the first growth is plenty.
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151 | */
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152 | void grow_config(int len)
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153 | {
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154 | while (len_config + len > size_config) {
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155 | if (size_config == 0)
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156 | size_config = 2048;
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157 | str_config = realloc(str_config, size_config *= 2);
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158 | if (str_config == NULL)
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159 | { perror("fixdep:malloc"); exit(1); }
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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 | /*
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166 | * Lookup a value in the configuration string.
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167 | */
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168 | int is_defined_config(const char * name, int len)
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169 | {
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170 | const char * pconfig;
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171 | const char * plast = str_config + len_config - len;
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172 | for ( pconfig = str_config + 1; pconfig < plast; pconfig++ ) {
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173 | if (pconfig[ -1] == '\n'
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174 | && pconfig[len] == '\n'
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175 | && !memcmp(pconfig, name, len))
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176 | return 1;
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177 | }
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178 | return 0;
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179 | }
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180 |
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181 | /*
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182 | * Add a new value to the configuration string.
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183 | */
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184 | void define_config(const char * name, int len)
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185 | {
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186 | grow_config(len + 1);
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187 |
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188 | memcpy(str_config+len_config, name, len);
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189 | len_config += len;
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190 | str_config[len_config++] = '\n';
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191 | }
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192 |
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193 | /*
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194 | * Clear the set of configuration strings.
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195 | */
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196 | void clear_config(void)
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197 | {
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198 | len_config = 0;
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199 | define_config("", 0);
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200 | }
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201 |
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202 | /*
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203 | * Record the use of a CONFIG_* word.
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204 | */
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205 | void use_config(char *m, int slen)
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206 | {
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207 | char *s = alloca(slen+1);
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208 | char *p;
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209 |
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210 | if (is_defined_config(m, slen))
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211 | return;
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212 |
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213 | define_config(m, slen);
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214 |
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215 | memcpy(s, m, slen); s[slen] = 0;
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216 |
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217 | for (p = s; p < s + slen; p++) {
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218 | if (*p == '_')
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219 | *p = '/';
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220 | else
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221 | *p = tolower((int)*p);
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222 | }
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223 | printf(" $(wildcard include/config/%s.h) \\\n", s);
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224 | }
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225 |
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226 | void parse_config_file(char *map, size_t len)
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227 | {
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228 | /* modified for bbox */
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229 | char *end_3 = map + len - 3; /* 3 == length of "IF_" */
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230 | char *end_7 = map + len - 7;
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231 | char *p = map;
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232 | char *q;
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233 | int off;
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234 |
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235 | for (; p <= end_3; p++) {
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236 | /* Find next identifier's beginning */
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237 | if (!(isalnum(*p) || *p == '_'))
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238 | continue;
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239 |
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240 | /* Check it */
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241 | if (p < end_7 && p[6] == '_') {
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242 | if (!memcmp(p, "CONFIG", 6)) goto conf7;
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243 | if (!memcmp(p, "ENABLE", 6)) goto conf7;
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244 | if (!memcmp(p, "IF_NOT", 6)) goto conf7;
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245 | }
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246 | /* we have at least 3 chars because of p <= end_3 */
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247 | /*if (!memcmp(p, "IF_", 3)) ...*/
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248 | if (p[0] == 'I' && p[1] == 'F' && p[2] == '_') {
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249 | off = 3;
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250 | goto conf;
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251 | }
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252 |
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253 | /* This identifier is not interesting, skip it */
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254 | while (p <= end_3 && (isalnum(*p) || *p == '_'))
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255 | p++;
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256 | continue;
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257 |
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258 | conf7: off = 7;
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259 | conf:
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260 | p += off;
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261 | for (q = p; q < end_3+3; q++) {
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262 | if (!(isalnum(*q) || *q == '_'))
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263 | break;
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264 | }
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265 | if (q != p) {
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266 | use_config(p, q-p);
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267 | }
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268 | }
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269 | }
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270 |
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271 | /* test is s ends in sub */
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272 | int strrcmp(char *s, char *sub)
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273 | {
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274 | int slen = strlen(s);
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275 | int sublen = strlen(sub);
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276 |
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277 | if (sublen > slen)
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278 | return 1;
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279 |
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280 | return memcmp(s + slen - sublen, sub, sublen);
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281 | }
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282 |
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283 | void do_config_file(char *filename)
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284 | {
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285 | struct stat st;
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286 | int fd;
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287 | void *map;
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288 |
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289 | fd = open(filename, O_RDONLY);
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290 | if (fd < 0) {
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291 | fprintf(stderr, "fixdep: ");
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292 | perror(filename);
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293 | exit(2);
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294 | }
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295 | fstat(fd, &st);
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296 | if (st.st_size == 0) {
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297 | close(fd);
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298 | return;
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299 | }
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300 | map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
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301 | if ((long) map == -1) {
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302 | perror("fixdep: mmap");
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303 | close(fd);
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304 | return;
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305 | }
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306 |
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307 | parse_config_file(map, st.st_size);
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308 |
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309 | munmap(map, st.st_size);
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310 |
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311 | close(fd);
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312 | }
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313 |
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314 | void parse_dep_file(void *map, size_t len)
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315 | {
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316 | char *m = map;
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317 | char *end = m + len;
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318 | char *p;
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319 | char *s = alloca(len);
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320 |
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321 | p = memchr(m, ':', len);
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322 | if (!p) {
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323 | fprintf(stderr, "fixdep: parse error\n");
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324 | exit(1);
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325 | }
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326 | memcpy(s, m, p-m); s[p-m] = 0;
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327 | printf("deps_%s := \\\n", target);
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328 | m = p+1;
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329 |
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330 | clear_config();
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331 |
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332 | while (m < end) {
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333 | while (m < end && (*m == ' ' || *m == '\\' || *m == '\n' || *m == '\r'))
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334 | m++;
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335 | p = m;
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336 | while (p < end && *p != ' ') p++;
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337 | if (p == end) {
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338 | do p--; while (!isalnum(*p));
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339 | p++;
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340 | }
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341 | memcpy(s, m, p-m); s[p-m] = 0;
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342 | if (strrcmp(s, "include/autoconf.h") &&
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343 | strrcmp(s, "arch/um/include/uml-config.h") &&
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344 | strrcmp(s, ".ver")) {
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345 | printf(" %s \\\n", s);
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346 | do_config_file(s);
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347 | }
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348 | m = p + 1;
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349 | }
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350 | printf("\n%s: $(deps_%s)\n\n", target, target);
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351 | printf("$(deps_%s):\n", target);
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352 | }
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353 |
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354 | void print_deps(void)
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355 | {
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356 | struct stat st;
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357 | int fd;
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358 | void *map;
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359 |
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360 | fd = open(depfile, O_RDONLY);
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361 | if (fd < 0) {
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362 | fprintf(stderr, "fixdep: ");
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363 | perror(depfile);
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364 | exit(2);
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365 | }
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366 | fstat(fd, &st);
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367 | if (st.st_size == 0) {
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368 | fprintf(stderr,"fixdep: %s is empty\n",depfile);
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369 | close(fd);
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370 | return;
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371 | }
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372 | map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
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373 | if ((long) map == -1) {
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374 | perror("fixdep: mmap");
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375 | close(fd);
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376 | return;
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377 | }
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378 |
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379 | parse_dep_file(map, st.st_size);
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380 |
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381 | munmap(map, st.st_size);
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382 |
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383 | close(fd);
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384 | }
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385 |
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386 | void traps(void)
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387 | {
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388 | /* bbox: not needed
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389 | static char test[] __attribute__((aligned(sizeof(int)))) = "CONF";
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390 |
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391 | if (*(int *)test != INT_CONF) {
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392 | fprintf(stderr, "fixdep: sizeof(int) != 4 or wrong endianess? %#x\n",
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393 | *(int *)test);
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394 | exit(2);
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395 | }
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396 | */
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397 | }
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398 |
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399 | int main(int argc, char **argv)
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400 | {
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401 | traps();
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402 |
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403 | if (argc != 4)
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404 | usage();
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405 |
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406 | depfile = argv[1];
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407 | target = argv[2];
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408 | cmdline = argv[3];
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409 |
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410 | print_cmdline();
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411 | print_deps();
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412 |
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413 | return 0;
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414 | }
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