Add realpath function
This commit is contained in:
Erik van der Kouwe
parent
150dfbe96d
commit
5427ab41c8
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@ -69,6 +69,8 @@ _PROTOTYPE( int mkstemp, (char *_fmt) );
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_PROTOTYPE( char *initstate, (unsigned _seed, char *_state,
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size_t _size) );
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_PROTOTYPE( long random, (void) );
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_PROTOTYPE( char *realpath, (const char *file_name,
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char *resolved_name) );
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_PROTOTYPE( char *setstate, (const char *state) );
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_PROTOTYPE( void srandom, (unsigned seed) );
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_PROTOTYPE( int putenv, (char *string) );
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@ -75,6 +75,7 @@ libc_FILES=" \
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putenv.c \
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putw.c \
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random.c \
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realpath.c \
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rindex.c \
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setenv.c \
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setgroups.c \
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221
lib/other/realpath.c
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221
lib/other/realpath.c
Normal file
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@ -0,0 +1,221 @@
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/* realpath() - resolve absolute path Author: Erik van der Kouwe
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* 4 December 2009
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*
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* Based on this specification:
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* http://www.opengroup.org/onlinepubs/000095399/functions/realpath.html
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*/
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#include <errno.h>
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#include <limits.h>
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#include <string.h>
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#include <sys/stat.h>
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#include <unistd.h>
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static char *append_path_component(char *path, const char *component,
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size_t component_length);
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static char *process_path_component(const char *component,
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size_t component_length, char *resolved_name, int last_part, int max_depth);
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static char *realpath_recurse(const char *file_name, char *resolved_name,
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int max_depth);
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static char *remove_last_path_component(char *path);
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static char *append_path_component(char *path, const char *component,
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size_t component_length)
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{
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size_t path_length, slash_length;
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/* insert or remove a slash? */
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path_length = strlen(path);
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slash_length =
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((path[path_length - 1] == '/') ? 0 : 1) +
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((component[0] == '/') ? 0 : 1) - 1;
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/* check whether this fits */
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if (path_length + slash_length + component_length >= PATH_MAX)
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{
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errno = ENAMETOOLONG;
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return NULL;
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}
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/* insert slash if needed */
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if (slash_length > 0)
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path[path_length] = '/';
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/* copy the bytes */
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memcpy(path + path_length + slash_length, component, component_length);
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path[path_length + slash_length + component_length] = 0;
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return path;
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}
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static char *process_path_component(const char *component,
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size_t component_length, char *resolved_name, int last_part, int max_depth)
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{
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char readlink_buffer[PATH_MAX + 1];
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ssize_t readlink_buffer_length;
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struct stat stat_buffer;
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/* handle zero-length components */
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if (!component_length)
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{
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if (last_part)
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return resolved_name;
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else
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{
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errno = ENOENT;
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return NULL;
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}
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}
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/* ignore current directory components */
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if (component_length == 1 && component[0] == '.')
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return resolved_name;
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/* process parent directory components */
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if (component_length == 2 && component[0] == '.' && component[1] == '.')
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return remove_last_path_component(resolved_name);
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/* not a special case, so just add the component */
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if (!append_path_component(resolved_name, component, component_length))
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return NULL;
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/* stat partially resolved file */
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if (lstat(resolved_name, &stat_buffer) < 0)
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{
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if (last_part && errno == ENOENT)
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return resolved_name;
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else
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return NULL;
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}
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if (S_ISLNK(stat_buffer.st_mode))
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{
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/* resolve symbolic link */
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readlink_buffer_length = readlink(resolved_name, readlink_buffer,
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sizeof(readlink_buffer) - 1);
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if (readlink_buffer_length < 0)
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return NULL;
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readlink_buffer[readlink_buffer_length] = 0;
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/* recurse to resolve path in link */
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remove_last_path_component(resolved_name);
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if (!realpath_recurse(readlink_buffer, resolved_name, max_depth - 1))
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return NULL;
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/* stat symlink target */
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if (lstat(resolved_name, &stat_buffer) < 0)
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{
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if (last_part && errno == ENOENT)
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return resolved_name;
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else
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return NULL;
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}
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}
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/* non-directories may appear only as the last component */
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if (!last_part && !S_ISDIR(stat_buffer.st_mode))
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{
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errno = ENOTDIR;
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return NULL;
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}
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return resolved_name;
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}
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static char *realpath_recurse(const char *file_name, char *resolved_name,
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int max_depth)
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{
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const char *file_name_component;
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/* avoid infinite recursion */
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if (max_depth <= 0)
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{
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errno = ELOOP;
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return NULL;
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}
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/* relative to root or to current? */
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if (file_name[0] == '/')
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{
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/* relative to root */
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resolved_name[0] = '/';
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resolved_name[1] = '\0';
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file_name++;
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}
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/* process the path component by component */
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while (*file_name)
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{
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/* extract a slash-delimited component */
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file_name_component = file_name;
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while (*file_name && *file_name != '/')
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file_name++;
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/* check length of component */
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if (file_name - file_name_component > PATH_MAX)
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{
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errno = ENAMETOOLONG;
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return NULL;
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}
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/* add the component to the current result */
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if (!process_path_component(
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file_name_component,
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file_name - file_name_component,
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resolved_name,
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!*file_name,
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max_depth))
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return NULL;
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/* skip the slash */
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if (*file_name == '/')
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file_name++;
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}
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return resolved_name;
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}
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static char *remove_last_path_component(char *path)
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{
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char *current, *slash;
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/* find the last slash */
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slash = NULL;
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for (current = path; *current; current++)
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if (*current == '/')
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slash = current;
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/* truncate after the last slash, but do not remove the root */
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if (slash > path)
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*slash = 0;
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else if (slash == path)
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slash[1] = 0;
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return path;
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}
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char *realpath(const char *file_name, char *resolved_name)
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{
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/* check parameters */
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if (!file_name || !resolved_name)
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{
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errno = EINVAL;
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return NULL;
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}
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if (strlen(file_name) > PATH_MAX)
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{
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errno = ENAMETOOLONG;
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return NULL;
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}
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/* basis to resolve against: root or CWD */
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if (file_name[0] == '/')
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*resolved_name = 0;
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else if (!getcwd(resolved_name, PATH_MAX))
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return NULL;
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/* do the actual work */
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return realpath_recurse(file_name, resolved_name, SYMLOOP_MAX);
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}
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20
man/man3/realpath.3
Normal file
20
man/man3/realpath.3
Normal file
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@ -0,0 +1,20 @@
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.TH REALPATH 3 "December 3, 2009"
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.UC 4
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.SH NAME
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realpath \- resolve a pathname
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.SH SYNOPSIS
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.nf
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.ft B
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#include <stdlib.h>
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char *realpath(const char *\fIfile_name\fP, char *\fIresolved_name\fP);
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.fi
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.SH DESCRIPTION
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realpath finds an absolute path to \fIfile_name\fP which does not
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contain . and .. components or symbolic links. The absolute path is stored
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in \fIresolved_name\fP, which is expected to provide storage for at least
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MAX_PATH bytes.
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.SH "RETURN VALUE
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If the function succeeds, a pointer to \fIresolved_name\fP is returned.
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If the function fails, NULL is returned and errno is set to indicate the
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cause of the failure.
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@ -8,7 +8,7 @@ OBJ= test1 test2 test3 test4 test5 test6 test7 test8 test9 \
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test21 test22 test23 test25 test26 test27 test28 test29 \
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test30 test31 test32 test34 test35 test36 test37 test38 \
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test39 t10a t11a t11b test40 t40a t40b t40c t40d t40e t40f test41 \
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test42
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test42 test43
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BIGOBJ= test20 test24
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ROOTOBJ= test11 test33
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@ -83,3 +83,4 @@ t40e: t40e.c
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t40f: t40f.c
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test41: test41.c
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test42: test42.c
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test43: test43.c
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4
test/run
4
test/run
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@ -12,13 +12,13 @@ badones= # list of tests that failed
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# Print test welcome message
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clr
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echo "Running POSIX compliance test suite. There are 44 tests in total."
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echo "Running POSIX compliance test suite. There are 45 tests in total."
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echo " "
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# Run all the tests, keeping track of who failed.
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for i in 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 \
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21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 \
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41 42 sh1.sh sh2.sh
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41 42 43 sh1.sh sh2.sh
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do total=`expr $total + 1`
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FAIL=0
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if [ $USER = root -a \( $i = 11 -o $i = 33 \) ]
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283
test/test43.c
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283
test/test43.c
Normal file
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@ -0,0 +1,283 @@
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/* Tests for MINIX3 realpath(3) - by Erik van der Kouwe */
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#define _POSIX_SOURCE 1
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#include <assert.h>
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#include <dirent.h>
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#include <errno.h>
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#include <limits.h>
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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 <sys/stat.h>
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#include <unistd.h>
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#define MAX_ERROR 4
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static int errct = 0;
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static const char *executable, *subtest;
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#define ERR (e(__LINE__))
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static void e(int n)
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{
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printf("File %s, error line %d, errno %d: %s\n",
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subtest, n, errno, strerror(errno));
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if (errct++ > MAX_ERROR)
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{
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printf("Too many errors; test aborted\n");
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exit(1);
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}
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}
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static void quit(void)
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{
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if (errct == 0)
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{
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printf("ok\n");
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exit(0);
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}
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else
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{
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printf("%d errors\n", errct);
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exit(1);
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}
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}
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static char *remove_last_path_component(char *path)
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{
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char *current, *last;
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assert(path);
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/* find last slash */
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last = NULL;
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for (current = path; *current; current++)
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if (*current == '/')
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last = current;
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/* check path component */
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if (last)
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{
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if (strcmp(last + 1, ".") == 0) ERR;
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if (strcmp(last + 1, "..") == 0) ERR;
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}
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/* if only root path slash, we are done */
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if (last <= path)
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return NULL;
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/* chop off last path component */
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*last = 0;
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return path;
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}
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static void check_realpath(const char *path, int expected_errno)
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{
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char buffer[PATH_MAX + 1], *resolved_path;
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struct stat statbuf[2];
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assert(path);
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/* run realpath */
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subtest = path;
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resolved_path = realpath(path, buffer);
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/* do we get errors when expected? */
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if (expected_errno)
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{
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if (errno != expected_errno) ERR;
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if (resolved_path) ERR;
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subtest = NULL;
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return;
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}
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/* do we get success when expected? */
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if (!resolved_path)
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{
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ERR;
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subtest = NULL;
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return;
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}
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errno = 0;
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/* do the paths point to the same file? */
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if (stat(path, &statbuf[0]) < 0) { ERR; return; }
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if (stat(resolved_path, &statbuf[1]) < 0) { ERR; return; }
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if (statbuf[0].st_dev != statbuf[1].st_dev) ERR;
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if (statbuf[0].st_ino != statbuf[1].st_ino) ERR;
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/* is the path absolute? */
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if (resolved_path[0] != '/') ERR;
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/* is each path element allowable? */
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while (remove_last_path_component(resolved_path))
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{
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/* not a symlink? */
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if (lstat(resolved_path, &statbuf[1]) < 0) { ERR; return; }
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if ((statbuf[1].st_mode & S_IFMT) != S_IFDIR) ERR;
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}
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subtest = NULL;
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}
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static void check_realpath_step_by_step(const char *path, int expected_errno)
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{
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char buffer[PATH_MAX + 1];
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const char *path_current;
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assert(path);
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assert(strlen(path) < sizeof(buffer));
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/* check the absolute path */
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check_realpath(path, expected_errno);
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/* try with different CWDs */
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for (path_current = path; *path_current; path_current++)
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if (path_current[0] == '/' && path_current[1])
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{
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/* set CWD */
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memcpy(buffer, path, path_current - path + 1);
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buffer[path_current - path + 1] = 0;
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if (chdir(buffer) < 0) { ERR; continue; }
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/* perform test */
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check_realpath(path_current + 1, expected_errno);
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}
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}
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static char *pathncat(char *buffer, size_t size, const char *path1, const char *path2)
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{
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size_t len1, len2, lenslash;
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assert(buffer);
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assert(path1);
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assert(path2);
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/* check whether it fits */
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len1 = strlen(path1);
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len2 = strlen(path2);
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lenslash = (len1 > 0 && path1[len1 - 1] == '/') ? 0 : 1;
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if (len1 >= size || /* check individual components to avoid overflow */
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len2 >= size ||
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len1 + len2 + lenslash >= size)
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return NULL;
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/* perform the copy */
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memcpy(buffer, path1, len1);
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if (lenslash)
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buffer[len1] = '/';
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memcpy(buffer + len1 + lenslash, path2, len2 + 1);
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return buffer;
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}
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static void check_realpath_recurse(const char *path, int depth)
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{
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DIR *dir;
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struct dirent *dirent;
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char pathsub[PATH_MAX + 1];
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/* check with the path itself */
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check_realpath_step_by_step(path, 0);
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/* don't go too deep */
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if (depth < 1)
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return;
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/* loop through subdirectories (including . and ..) */
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if (!(dir = opendir(path)))
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{
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if (errno != ENOTDIR)
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ERR;
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return;
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}
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while (dirent = readdir(dir))
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{
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/* build path */
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if (!pathncat(pathsub, sizeof(pathsub), path, dirent->d_name))
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{
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ERR;
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continue;
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}
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/* check path */
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check_realpath_recurse(pathsub, depth - 1);
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}
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if (closedir(dir) < 0) ERR;
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}
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#define PATH_DEPTH 3
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#define L(x) "/t43_link_" #x ".tmp"
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static char basepath[PATH_MAX + 1];
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static char *addbasepath(char *buffer, const char *path)
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{
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size_t basepathlen, pathlen;
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int slashlen;
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/* assumption: both start with slash and neither end with it */
|
||||
assert(basepath[0] == '/');
|
||||
assert(basepath[strlen(basepath) - 1] != '/');
|
||||
assert(buffer);
|
||||
assert(path);
|
||||
assert(path[0] == '/');
|
||||
|
||||
/* check result length */
|
||||
basepathlen = strlen(basepath);
|
||||
pathlen = strlen(path);
|
||||
if (basepathlen + pathlen > PATH_MAX)
|
||||
{
|
||||
printf("path too long\n");
|
||||
exit(-1);
|
||||
}
|
||||
|
||||
/* concatenate base path and path */
|
||||
memcpy(buffer, basepath, basepathlen);
|
||||
memcpy(buffer + basepathlen, path, pathlen + 1);
|
||||
return buffer;
|
||||
}
|
||||
|
||||
static void cleanup(int silent)
|
||||
{
|
||||
char buffer[PATH_MAX + 1];
|
||||
|
||||
if (unlink(addbasepath(buffer, L(1))) < 0 && !silent) ERR;
|
||||
if (unlink(addbasepath(buffer, L(2))) < 0 && !silent) ERR;
|
||||
if (unlink(addbasepath(buffer, L(3))) < 0 && !silent) ERR;
|
||||
if (unlink(addbasepath(buffer, L(4))) < 0 && !silent) ERR;
|
||||
if (unlink(addbasepath(buffer, L(5))) < 0 && !silent) ERR;
|
||||
}
|
||||
|
||||
int main(int argc, char **argv)
|
||||
{
|
||||
char buffer1[PATH_MAX + 1], buffer2[PATH_MAX + 1];
|
||||
|
||||
/* initialize */
|
||||
printf("Test 43 ");
|
||||
fflush(stdout);
|
||||
executable = argv[0];
|
||||
getcwd(basepath, sizeof(basepath));
|
||||
cleanup(1);
|
||||
|
||||
/* prepare some symlinks to make it more difficult */
|
||||
if (symlink("/", addbasepath(buffer1, L(1))) < 0) ERR;
|
||||
if (symlink(basepath, addbasepath(buffer1, L(2))) < 0) ERR;
|
||||
|
||||
/* perform some tests */
|
||||
check_realpath_recurse(basepath, PATH_DEPTH);
|
||||
|
||||
/* now try with recursive symlinks */
|
||||
if (symlink(addbasepath(buffer1, L(3)), addbasepath(buffer2, L(3))) < 0) ERR;
|
||||
if (symlink(addbasepath(buffer1, L(5)), addbasepath(buffer2, L(4))) < 0) ERR;
|
||||
if (symlink(addbasepath(buffer1, L(4)), addbasepath(buffer2, L(5))) < 0) ERR;
|
||||
check_realpath_step_by_step(addbasepath(buffer1, L(3)), ELOOP);
|
||||
check_realpath_step_by_step(addbasepath(buffer1, L(4)), ELOOP);
|
||||
check_realpath_step_by_step(addbasepath(buffer1, L(5)), ELOOP);
|
||||
|
||||
/* delete the symlinks */
|
||||
cleanup(0);
|
||||
|
||||
/* done */
|
||||
quit();
|
||||
return(-1); /* impossible */
|
||||
}
|
||||
Loading…
Reference in a new issue