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1 #include <sys/stat.h>
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2 #include <sys/types.h>
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3 #include <unistd.h>
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4 #include <stdio.h>
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5 #include <errno.h>
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6 #include <stdlib.h>
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7 #include <pwd.h>
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8 #include <grp.h> // declares struct group
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9 #include <libgen.h> // for dirname
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10 #include <string.h> // for strcpy
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11
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12 /* cpx.c David Hoover 1/13/11
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13 usage:
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14 cpx from.file to.file login
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15
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16 cpx copies a file from one location to another, but only if the original file is owned by the given login. The
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17 program is expected to be setuid and owned by root.
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18
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19 */
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20
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21 int notReadable(char *file, char *user)
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22 /* Returns 1 if file not readable by given user */
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23 {
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24 struct stat fileStat;
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25 struct passwd *own,*usr;
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26 struct group *grp;
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27 int i=0;
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28
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29 usr = getpwnam(user);
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30
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31 /* does user exist? */
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32 if (! usr)
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33 {
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34 fprintf(stderr,"%s: No such user\n",user);
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35 exit(1);
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36 }
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37
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38 /* must be able to stat file */
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39 if (stat(file, &fileStat) < 0)
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40 {
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41 fprintf(stderr,"%s: No such file\n",file);
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42 exit(1);
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43 }
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44
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45 /* get the owner and group information for the file */
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46 own = getpwuid(fileStat.st_uid);
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47 grp = getgrgid(fileStat.st_gid);
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48
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49 /* does the file owner match the argument? */
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50 // if (!strcmp(own->pw_name,user))
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51 if (usr->pw_uid == fileStat.st_uid)
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52 {
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53 // printf("owners match!\n");
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54
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55 /* is file readable? */
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56 if (fileStat.st_mode & S_IRUSR)
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57 {
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58 // printf("%s is readable by %s\n",file,user);
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59 return 0;
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60 }
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61 else
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62 {
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63 // printf("%s is not readable by %s\n",file,user);
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64 }
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65 }
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66 else {
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67 // printf("owners don't match!\n");
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68 }
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69
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70 /* is the file group readable by the given group? */
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71 if (fileStat.st_mode & S_IRGRP)
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72 {
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73 // printf("%s is readable by group %s\n",file,grp->gr_name);
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74
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75
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76 /* is the user's gid the same as the file? */
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77 // printf("%d\n",usr->pw_gid);
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78 // printf("%d\n",fileStat.st_gid);
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79 if (usr->pw_gid == fileStat.st_gid)
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80 {
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81 // printf("groups match!\n");
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82
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83 /* if the path a directory is it executable? */
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84 if (S_ISDIR(fileStat.st_mode))
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85 {
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86 if (fileStat.st_mode & S_IXGRP)
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87 {
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88 return 0;
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89 }
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90 }
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91 else {
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92 return 0;
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93 }
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94 }
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95 else
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96 {
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97
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98 /* is the user a member of the group that owns the file? */
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99 while(grp->gr_mem[i] != NULL)
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100 {
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101 if(!strcmp(grp->gr_mem[i],user))
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102 {
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103 // printf("%s is a member of the %s group\n",user,grp->gr_name);
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104 /* if the path a directory is it executable? */
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105 if (S_ISDIR(fileStat.st_mode))
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106 {
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107 if (fileStat.st_mode & S_IXGRP)
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108 {
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109 return 0;
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110 }
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111 }
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112 else {
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113 return 0;
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114 }
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115 }
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116 i++;
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117 }
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118
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119 // printf("%s is not a member of the %s group\n",user,grp->gr_name);
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120
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121 }
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122 }
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123 else
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124 {
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125 // printf("%s is not readable by group %s\n",file,grp->gr_name);
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126 }
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127
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128 /* is the e world readable? */
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129 if (fileStat.st_mode & S_IROTH)
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130 {
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131 // printf("%s is world readable\n",file);
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132 return 0;
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133 }
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134 else
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135 {
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136 // printf("%s is not world readable\n",file);
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137 }
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138
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139 return 1;
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140 }
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141
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142 int copyFile(char *src, char *dst)
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143 {
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144 // printf("Copying %s to %s\n",src,dst);
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145
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146 int c;
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147 FILE *fs,*ft;
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148 struct stat fileStat;
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149
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150 /* must be able to stat file */
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151 if (stat(src, &fileStat) < 0)
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152 {
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153 fprintf(stderr,"%s: No such file\n",src);
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154 exit(1);
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155 }
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156
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157 /* is path a regular file? */
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158 if (S_ISDIR(fileStat.st_mode))
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159 {
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160 fprintf(stderr,"%s: Is a directory\n",src);
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161 exit(1);
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162 }
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163
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164 fs = fopen(src,"r");
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165 if (fs==NULL) {
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166 fprintf(stderr,"Can't read from file %s!\n",src);
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167 exit(1);
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168 }
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169 ft = fopen(dst,"w");
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170 if (ft==NULL) {
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171 fprintf(stderr,"Can't write to file %s!\n",dst);
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172 exit(1);
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173 }
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174
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175 c = getc(fs);
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176 while (c != EOF) {
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177 putc(c,ft);
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178 c = getc(fs);
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179 }
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180
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181 fclose(fs);
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182 fclose(ft);
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183
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184 return 0;
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185
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186 }
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187
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188 int chownToUser(char *file)
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189 /* chown a file to the user running cpx */
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190 {
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191 uid_t uid;
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192 gid_t gid;
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193
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194 uid = getuid();
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195 gid = getgid();
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196
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197 // printf("UID = %d\n",uid);
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198 // printf("GID = %d\n",gid);
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199
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200 // printf("chown %s %d,%d\n",file,uid,gid);
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201 if (chown(file,uid,gid))
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202 {
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203 fprintf(stderr,"Can't chown %s\n",file);
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204 exit(1);
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205 }
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206 return 0;
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207 }
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208
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209 int explodePath(char *file, char *user)
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210 /* Returns 1 if file not readable by given user */
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211 {
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212 char **path;
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213 char *dir;
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214 char newfile[10000];
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215 int i;
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216
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217 strcpy(newfile,file);
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218 if (!notReadable(newfile,user))
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219 {
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220 dir = dirname(newfile);
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221 if (strcmp(dir,"/"))
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222 explodePath(dir,user);
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223 }
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224 else
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225 {
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226 fprintf(stderr,"%s: Permission denied.\n",file);
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227 exit(1);
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228 }
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229
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230 return 0;
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231 }
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232
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233 main(int argc, char **argv)
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234 {
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235
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236 /* must have two arguments */
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237 if (argc != 4)
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238 {
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239 fprintf(stderr,"usage: cpx source dest user\n");
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240 exit(1);
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241 }
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242
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243 /* is file readable by given user? */
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244 explodePath(argv[1],argv[3]);
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245
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246 /* copy the file and change the owner */
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247 copyFile(argv[1],argv[2]);
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248 chownToUser(argv[2]);
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249
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250 exit(0);
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251 }
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