From bb40841634386d53c7e83d88f40396fa8ee83e3c Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?P=C3=A1draig=20Brady?= Date: Thu, 29 Dec 2011 23:49:53 +0000 Subject: [PATCH] canonicalize: add support for not resolving symlinks This will initially be used by a new coreutils realpath command. * lib/canonicalize.h: Add the CAN_NOLINKS flag to indicate we don't want to follow symlinks. Also provide CAN_MODE_MASK to aid setting these existing mutually exclusive values. * lib/canonicalize.c (canonicalize_filename_mode): Extract the flags from can_mode parameter, which are currently just used to select between stat() and lstat(). Also ensure that mutually exclusive values and flagged immediately as invalid. * tests/test-canonicalize.c: Verify symlinks are not followed, and that invalid flag combinations are diagnosed. --- ChangeLog | 16 ++++++++++++++++ lib/canonicalize.c | 18 +++++++++++++++--- lib/canonicalize.h | 10 +++++++++- tests/test-canonicalize.c | 12 ++++++++++++ 4 files changed, 52 insertions(+), 4 deletions(-) diff --git a/ChangeLog b/ChangeLog index cc50b4a..06dfe77 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,3 +1,19 @@ +2011-12-29 Pádraig Brady + + canonicalize: add support for not resolving symlinks + * lib/canonicalize.h: Add the CAN_NOLINKS flag to + indicate we don't want to follow symlinks. Also + provide CAN_MODE_MASK to aid setting these existing + mutually exclusive values. + * lib/canonicalize.c (canonicalize_filename_mode): + Extract the flags from can_mode parameter, which + are currently just used to select between stat() + and lstat(). Also ensure that mutually exclusive + values and flagged immediately as invalid. + * tests/test-canonicalize.c: Verify symlinks are + not followed, and that invalid flag combinations + are diagnosed. + 2011-12-25 Jim Meyering gitlog-to-changelog: do not clump multi-paragraph entries diff --git a/lib/canonicalize.c b/lib/canonicalize.c index 4fe9f30..c73a963 100644 --- a/lib/canonicalize.c +++ b/lib/canonicalize.c @@ -31,6 +31,8 @@ #include "xalloc.h" #include "xgetcwd.h" +#define MULTIPLE_BITS_SET(i) (((i) & ((i) - 1)) != 0) + /* In this file, we cannot handle file names longer than PATH_MAX. On systems with no file name length limit, use a fallback. */ #ifndef PATH_MAX @@ -82,8 +84,9 @@ seen_triple (Hash_table **ht, char const *filename, struct stat const *st) /* Return the canonical absolute name of file NAME, while treating missing elements according to CAN_MODE. A canonical name does not contain any `.', `..' components nor any repeated file name - separators ('/') or symlinks. Whether components must exist - or not depends on canonicalize mode. The result is malloc'd. */ + separators ('/') or, depdending on other CAN_MODE flags, symlinks. + Whether components must exist or not depends on canonicalize mode. + The result is malloc'd. */ char * canonicalize_filename_mode (const char *name, canonicalize_mode_t can_mode) @@ -95,6 +98,15 @@ canonicalize_filename_mode (const char *name, canonicalize_mode_t can_mode) size_t extra_len = 0; Hash_table *ht = NULL; int saved_errno; + int can_flags = can_mode & ~CAN_MODE_MASK; + can_mode &= CAN_MODE_MASK; + bool logical = can_flags & CAN_NOLINKS; + + if (MULTIPLE_BITS_SET (can_mode)) + { + errno = EINVAL; + return NULL; + } if (name == NULL) { @@ -185,7 +197,7 @@ canonicalize_filename_mode (const char *name, canonicalize_mode_t can_mode) dest += end - start; *dest = '\0'; - if (lstat (rname, &st) != 0) + if ((logical?stat:lstat) (rname, &st) != 0) { saved_errno = errno; if (can_mode == CAN_EXISTING) diff --git a/lib/canonicalize.h b/lib/canonicalize.h index 04ad79c..4bb5898 100644 --- a/lib/canonicalize.h +++ b/lib/canonicalize.h @@ -19,6 +19,8 @@ #include /* for canonicalize_file_name */ +#define CAN_MODE_MASK (CAN_EXISTING | CAN_ALL_BUT_LAST | CAN_MISSING) + enum canonicalize_mode_t { /* All components must exist. */ @@ -28,7 +30,13 @@ enum canonicalize_mode_t CAN_ALL_BUT_LAST = 1, /* No requirements on components existence. */ - CAN_MISSING = 2 + CAN_MISSING = 2, + + /* Don't expand symlinks. */ + CAN_NOLINKS = 4, + + /* Modify the original (Not yet supported). */ + CAN_NOALLOC = 8 }; typedef enum canonicalize_mode_t canonicalize_mode_t; diff --git a/tests/test-canonicalize.c b/tests/test-canonicalize.c index a095e0e..9f1b876 100644 --- a/tests/test-canonicalize.c +++ b/tests/test-canonicalize.c @@ -82,6 +82,9 @@ main (void) result2 = canonicalize_filename_mode (NULL, CAN_EXISTING); ASSERT (result2 == NULL); ASSERT (errno == EINVAL); + result2 = canonicalize_filename_mode (".", CAN_MISSING | CAN_ALL_BUT_LAST); + ASSERT (result2 == NULL); + ASSERT (errno == EINVAL); } /* Check that a non-directory with trailing slash yields NULL. */ @@ -134,6 +137,15 @@ main (void) ASSERT (symlink ("../s/2", BASE "/d/1") == 0); ASSERT (symlink ("//.//../..", BASE "/droot") == 0); + /* Check that symbolic links are not resolved, with CAN_NOLINKS. */ + { + char *result1 = canonicalize_filename_mode (BASE "/huk", CAN_NOLINKS); + ASSERT (result1 != NULL); + ASSERT (strcmp (result1 + strlen (result1) - strlen ("/" BASE "/huk"), + "/" BASE "/huk") == 0); + free (result1); + } + /* Check that the symbolic link to a file can be resolved. */ { char *result1 = canonicalize_file_name (BASE "/huk"); -- 1.7.6.4