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/** |
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* Copyright (c) Members of the EGEE Collaboration. 2010. |
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* See http://www.eu-egee.org/partners/ for details on the copyright |
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* holders. |
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* |
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* Licensed under the Apache License, Version 2.0 (the "License"); |
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* you may not use this file except in compliance with the License. |
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* You may obtain a copy of the License at |
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* |
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* http://www.apache.org/licenses/LICENSE-2.0 |
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* |
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* Unless required by applicable law or agreed to in writing, software |
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* distributed under the License is distributed on an "AS IS" BASIS, |
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
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* See the License for the specific language governing permissions and |
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* limitations under the License. |
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* |
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* Authors: Oscar Koeroo, Mischa Sall\'e, Aram Verstegen |
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* NIKHEF Amsterdam, the Netherlands |
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* <grid-mw-security@nikhef.nl> |
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*/ |
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|
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#include <stdio.h> |
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#include <stdlib.h> |
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#include <string.h> |
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#include <unistd.h> |
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#include <fcntl.h> |
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#include <limits.h> |
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#include <sys/types.h> |
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#include <sys/stat.h> |
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#include <errno.h> |
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|
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/* Make sure at least internally we have a PATH_MAX */ |
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#ifndef PATH_MAX |
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#define PATH_MAX 1024 |
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#endif |
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|
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/* Make sure at least internally we have a SYMLOOP_MAX */ |
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#ifndef SYMLOOP_MAX |
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#define SYMLOOP_MAX _POSIX_SYMLOOP_MAX |
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#endif |
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|
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/*! |
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* Returns the fully canonicalized and absolute path for a diretory or NULL on |
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* error. Memory for the return string is malloced and should be freed by the |
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* caller. Any path cannot be longer than PATH_MAX. Note that it is necessary |
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* that we can chdir to dir. |
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* NOTE: This function is not thread-safe |
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* \param dir non-absolute and/or non-canonical directory |
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* \return canonical absolute directory |
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*/ |
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char *cgul_realdir(const char *dir) { |
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int olddir; |
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char buf[PATH_MAX],*path; |
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|
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/* Safe old dir and then go to the new one */ |
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if ( (olddir=open(".",O_RDONLY))==-1 || |
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chdir(dir)==-1 ) |
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return NULL; |
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/* Get the location, don't exit yet when failed: need to go back */ |
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path=getcwd(buf,PATH_MAX); |
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/* Go back, note that it's really bad if this fails! */ |
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if ( fchdir(olddir) || |
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close(olddir) ) |
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return NULL; |
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/* Make a copy */ |
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if (path) |
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path=strdup(buf); |
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|
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return path; |
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} |
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|
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/*! |
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* Returns the fully canonicalized and absolute path for any path or NULL on |
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* error. Note that this function substitutes the unsafe realpath() or the |
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* GNU-only canonicalize_file_name(). |
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* Memory for the return string is malloced and should be freed by the |
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* caller. Any path cannot be longer than PATH_MAX. Any directory has to be |
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* accessible, including if it's the last element. |
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* NOTE: This function is not thread-safe |
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* \param inpath non-absolute and/or non-canonical path |
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* \param instat optional stat information on the input (for performance, if |
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* already available). When NULL it will be determined locally |
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* when needed. |
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* \return canonical absolute path |
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*/ |
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char *cgul_realpath(const char *inpath, struct stat *instat) { |
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char buf[PATH_MAX], path[PATH_MAX]; |
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char *pos,*canonicdir; |
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int pathlen,filelen,linklen, linkcount=0; |
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struct stat st; |
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|
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/* Check and store the length of the input (incl \0) */ |
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if ( (pathlen=1+strlen(inpath)) > PATH_MAX) { |
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errno=ENAMETOOLONG; |
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return NULL; |
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} |
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/* Check last compo is dir: then just return realdir() */ |
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if (instat==NULL) { |
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if (stat(inpath, &st)==-1) /* Error */ |
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return NULL; |
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instat=&st; |
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} |
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if (S_ISDIR(instat->st_mode)) |
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return cgul_realdir(inpath); |
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|
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/* Make path absolute */ |
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if (inpath[0]!='/') { /* relative */ |
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/* get and add cwd */ |
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if (!getcwd(buf,PATH_MAX)) { |
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if (errno==ERANGE) errno=ENAMETOOLONG; |
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return NULL; |
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} |
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if ( (pathlen=snprintf(path,PATH_MAX,"%s/%s",buf,inpath))>PATH_MAX ) { |
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errno=ENAMETOOLONG; |
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return NULL; |
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} |
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} else /* absolute */ |
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strcpy(path,inpath); |
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|
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/* Now loop over symlink, if any */ |
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/* readlink wants buffersize without \0: PATH_MAX-1 */ |
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while ( (linklen=readlink(path,buf,PATH_MAX-1)) != -1 ) { |
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if (++linkcount > SYMLOOP_MAX) { /* Too many symlinks */ |
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errno=ELOOP; |
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return NULL; |
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} |
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buf[linklen]='\0'; |
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/* Check the symlink */ |
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if (buf[0]=='/') /* absolute: replaces entire path */ |
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strcpy(path,buf); |
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else { /* relative: replaces last component */ |
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pos=strrchr(path,'/'); /* Has to exist, we made it absolute */ |
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filelen=strlen(pos+1); /* length of remainder without \0 */ |
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/* Note: pathlen is with \0, filelen and linklen without, hence |
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* combined as follows is with \0 and should be <= PATH_MAX */ |
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if (pathlen-filelen+linklen>PATH_MAX) { |
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errno=ENAMETOOLONG; |
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return NULL; |
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} |
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strcpy(pos+1,buf); /* It fits, so use strcpy */ |
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} |
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} |
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/* Alway end due to realink: check it's due to non-symlink */ |
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if (errno!=EINVAL) /* i.e. other error */ |
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return NULL; |
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|
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/* Now path is not a symlink */ |
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|
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/* Find dir part */ |
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pos=strrchr(path,'/'); /* Has to exist, we made it absolute */ |
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/* dir: up to pos, file: pos+1 till end */ |
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pos[0]='\0'; |
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canonicdir=cgul_realdir(path); |
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pos[0]='/'; /* Clean but unnecessary */ |
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/* Put them together, canonicdir doesn't end with a / */ |
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pathlen=snprintf(buf,PATH_MAX,"%s/%s",canonicdir,pos+1); |
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free(canonicdir); /* Done with canonicdir */ |
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if (pathlen>PATH_MAX) { |
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errno=ENAMETOOLONG; |
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return NULL; |
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} |
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|
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/* Return duplicate, or NULL when fails */ |
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return strdup(buf); |
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} |
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