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-rw-r--r--gl/lib/canonicalize.c469
1 files changed, 469 insertions, 0 deletions
diff --git a/gl/lib/canonicalize.c b/gl/lib/canonicalize.c
new file mode 100644
index 0000000..d73ee2c
--- /dev/null
+++ b/gl/lib/canonicalize.c
@@ -0,0 +1,469 @@
+/* Return the canonical absolute name of a given file.
+ Copyright (C) 1996-2023 Free Software Foundation, Inc.
+
+ This program is free software: you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation, either version 3 of the License, or
+ (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program. If not, see <https://www.gnu.org/licenses/>. */
+
+#include <config.h>
+
+#include "canonicalize.h"
+
+#include <errno.h>
+#include <fcntl.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <unistd.h>
+
+#include <filename.h>
+#include <idx.h>
+#include <intprops.h>
+#include <scratch_buffer.h>
+
+#include "attribute.h"
+#include "file-set.h"
+#include "hash-triple.h"
+#include "xalloc.h"
+
+#ifndef DOUBLE_SLASH_IS_DISTINCT_ROOT
+# define DOUBLE_SLASH_IS_DISTINCT_ROOT false
+#endif
+
+#if ISSLASH ('\\')
+# define SLASHES "/\\"
+#else
+# define SLASHES "/"
+#endif
+
+/* Avoid false GCC warning "'end_idx' may be used uninitialized". */
+#if __GNUC__ + (__GNUC_MINOR__ >= 7) > 4
+# pragma GCC diagnostic ignored "-Wmaybe-uninitialized"
+#endif
+
+/* Return true if FILE's existence can be shown, false (setting errno)
+ otherwise. Follow symbolic links. */
+static bool
+file_accessible (char const *file)
+{
+# if HAVE_FACCESSAT
+ return faccessat (AT_FDCWD, file, F_OK, AT_EACCESS) == 0;
+# else
+ struct stat st;
+ return stat (file, &st) == 0 || errno == EOVERFLOW;
+# endif
+}
+
+/* True if concatenating END as a suffix to a file name means that the
+ code needs to check that the file name is that of a searchable
+ directory, since the canonicalize_filename_mode_stk code won't
+ check this later anyway when it checks an ordinary file name
+ component within END. END must either be empty, or start with a
+ slash. */
+
+static bool _GL_ATTRIBUTE_PURE
+suffix_requires_dir_check (char const *end)
+{
+ /* If END does not start with a slash, the suffix is OK. */
+ while (ISSLASH (*end))
+ {
+ /* Two or more slashes act like a single slash. */
+ do
+ end++;
+ while (ISSLASH (*end));
+
+ switch (*end++)
+ {
+ default: return false; /* An ordinary file name component is OK. */
+ case '\0': return true; /* Trailing "/" is trouble. */
+ case '.': break; /* Possibly "." or "..". */
+ }
+ /* Trailing "/.", or "/.." even if not trailing, is trouble. */
+ if (!*end || (*end == '.' && (!end[1] || ISSLASH (end[1]))))
+ return true;
+ }
+
+ return false;
+}
+
+/* Append this to a file name to test whether it is a searchable directory.
+ On POSIX platforms "/" suffices, but "/./" is sometimes needed on
+ macOS 10.13 <https://bugs.gnu.org/30350>, and should also work on
+ platforms like AIX 7.2 that need at least "/.". */
+
+#ifdef LSTAT_FOLLOWS_SLASHED_SYMLINK
+static char const dir_suffix[] = "/";
+#else
+static char const dir_suffix[] = "/./";
+#endif
+
+/* Return true if DIR is a searchable dir, false (setting errno) otherwise.
+ DIREND points to the NUL byte at the end of the DIR string.
+ Store garbage into DIREND[0 .. strlen (dir_suffix)]. */
+
+static bool
+dir_check (char *dir, char *dirend)
+{
+ strcpy (dirend, dir_suffix);
+ return file_accessible (dir);
+}
+
+#if !((HAVE_CANONICALIZE_FILE_NAME && FUNC_REALPATH_WORKS) \
+ || GNULIB_CANONICALIZE_LGPL)
+/* Return the canonical absolute name of file NAME. A canonical name
+ does not contain any ".", ".." components nor any repeated file name
+ separators ('/') or symlinks. All components must exist.
+ The result is malloc'd. */
+
+char *
+canonicalize_file_name (const char *name)
+{
+ return canonicalize_filename_mode (name, CAN_EXISTING);
+}
+#endif /* !HAVE_CANONICALIZE_FILE_NAME */
+
+static bool
+multiple_bits_set (canonicalize_mode_t i)
+{
+ return (i & (i - 1)) != 0;
+}
+
+/* Return true if we've already seen the triple, <FILENAME, dev, ino>.
+ If *HT is not initialized, initialize it. */
+static bool
+seen_triple (Hash_table **ht, char const *filename, struct stat const *st)
+{
+ if (*ht == NULL)
+ {
+ idx_t initial_capacity = 7;
+ *ht = hash_initialize (initial_capacity,
+ NULL,
+ triple_hash,
+ triple_compare_ino_str,
+ triple_free);
+ if (*ht == NULL)
+ xalloc_die ();
+ }
+
+ if (seen_file (*ht, filename, st))
+ return true;
+
+ record_file (*ht, filename, st);
+ return false;
+}
+
+/* Scratch buffers used by canonicalize_filename_mode_stk and managed
+ by __realpath. */
+struct realpath_bufs
+{
+ struct scratch_buffer rname;
+ struct scratch_buffer extra;
+ struct scratch_buffer link;
+};
+
+static char *
+canonicalize_filename_mode_stk (const char *name, canonicalize_mode_t can_mode,
+ struct realpath_bufs *bufs)
+{
+ char *dest;
+ char const *start;
+ char const *end;
+ Hash_table *ht = NULL;
+ bool logical = (can_mode & CAN_NOLINKS) != 0;
+ int num_links = 0;
+
+ canonicalize_mode_t can_exist = can_mode & CAN_MODE_MASK;
+ if (multiple_bits_set (can_exist))
+ {
+ errno = EINVAL;
+ return NULL;
+ }
+
+ if (name == NULL)
+ {
+ errno = EINVAL;
+ return NULL;
+ }
+
+ if (name[0] == '\0')
+ {
+ errno = ENOENT;
+ return NULL;
+ }
+
+ char *rname = bufs->rname.data;
+ bool end_in_extra_buffer = false;
+ bool failed = true;
+
+ /* This is always zero for Posix hosts, but can be 2 for MS-Windows
+ and MS-DOS X:/foo/bar file names. */
+ idx_t prefix_len = FILE_SYSTEM_PREFIX_LEN (name);
+
+ if (!IS_ABSOLUTE_FILE_NAME (name))
+ {
+ while (!getcwd (bufs->rname.data, bufs->rname.length))
+ {
+ switch (errno)
+ {
+ case ERANGE:
+ if (scratch_buffer_grow (&bufs->rname))
+ break;
+ FALLTHROUGH;
+ case ENOMEM:
+ xalloc_die ();
+
+ default:
+ dest = rname;
+ goto error;
+ }
+ rname = bufs->rname.data;
+ }
+ dest = rawmemchr (rname, '\0');
+ start = name;
+ prefix_len = FILE_SYSTEM_PREFIX_LEN (rname);
+ }
+ else
+ {
+ dest = mempcpy (rname, name, prefix_len);
+ *dest++ = '/';
+ if (DOUBLE_SLASH_IS_DISTINCT_ROOT)
+ {
+ if (prefix_len == 0 /* implies ISSLASH (name[0]) */
+ && ISSLASH (name[1]) && !ISSLASH (name[2]))
+ {
+ *dest++ = '/';
+#if defined _WIN32 && !defined __CYGWIN__
+ /* For UNC file names '\\server\path\to\file', extend the prefix
+ to include the server: '\\server\'. */
+ {
+ idx_t i;
+ for (i = 2; name[i] != '\0' && !ISSLASH (name[i]); )
+ i++;
+ if (name[i] != '\0' /* implies ISSLASH (name[i]) */
+ && i + 1 < bufs->rname.length)
+ {
+ prefix_len = i;
+ memcpy (dest, name + 2, i - 2 + 1);
+ dest += i - 2 + 1;
+ }
+ else
+ {
+ /* Either name = '\\server'; this is an invalid file name.
+ Or name = '\\server\...' and server is more than
+ bufs->rname.length - 4 bytes long. In either
+ case, stop the UNC processing. */
+ }
+ }
+#endif
+ }
+ *dest = '\0';
+ }
+ start = name + prefix_len;
+ }
+
+ for ( ; *start; start = end)
+ {
+ /* Skip sequence of multiple file name separators. */
+ while (ISSLASH (*start))
+ ++start;
+
+ /* Find end of component. */
+ for (end = start; *end && !ISSLASH (*end); ++end)
+ /* Nothing. */;
+
+ /* Length of this file name component; it can be zero if a file
+ name ends in '/'. */
+ idx_t startlen = end - start;
+
+ if (startlen == 0)
+ break;
+ else if (startlen == 1 && start[0] == '.')
+ /* nothing */;
+ else if (startlen == 2 && start[0] == '.' && start[1] == '.')
+ {
+ /* Back up to previous component, ignore if at root already. */
+ if (dest > rname + prefix_len + 1)
+ for (--dest; dest > rname && !ISSLASH (dest[-1]); --dest)
+ continue;
+ if (DOUBLE_SLASH_IS_DISTINCT_ROOT
+ && dest == rname + 1 && !prefix_len
+ && ISSLASH (*dest) && !ISSLASH (dest[1]))
+ dest++;
+ }
+ else
+ {
+ if (!ISSLASH (dest[-1]))
+ *dest++ = '/';
+
+ while (rname + bufs->rname.length - dest
+ < startlen + sizeof dir_suffix)
+ {
+ idx_t dest_offset = dest - rname;
+ if (!scratch_buffer_grow_preserve (&bufs->rname))
+ xalloc_die ();
+ rname = bufs->rname.data;
+ dest = rname + dest_offset;
+ }
+
+ dest = mempcpy (dest, start, startlen);
+ *dest = '\0';
+
+ char *buf;
+ ssize_t n = -1;
+ if (!logical)
+ {
+ while (true)
+ {
+ buf = bufs->link.data;
+ idx_t bufsize = bufs->link.length;
+ n = readlink (rname, buf, bufsize - 1);
+ if (n < bufsize - 1)
+ break;
+ if (!scratch_buffer_grow (&bufs->link))
+ xalloc_die ();
+ }
+ }
+ if (0 <= n)
+ {
+ /* A physical traversal and RNAME is a symbolic link. */
+
+ if (num_links < 20)
+ num_links++;
+ else if (*start)
+ {
+ /* Enough symlinks have been seen that it is time to
+ worry about being in a symlink cycle.
+ Get the device and inode of the parent directory, as
+ pre-2017 POSIX says this info is not reliable for
+ symlinks. */
+ struct stat st;
+ dest[- startlen] = '\0';
+ if (stat (*rname ? rname : ".", &st) != 0)
+ goto error;
+ dest[- startlen] = *start;
+
+ /* Detect loops. We cannot use the cycle-check module here,
+ since it's possible to encounter the same parent
+ directory more than once in a given traversal. However,
+ encountering the same (parentdir, START) pair twice does
+ indicate a loop. */
+ if (seen_triple (&ht, start, &st))
+ {
+ if (can_exist == CAN_MISSING)
+ continue;
+ errno = ELOOP;
+ goto error;
+ }
+ }
+
+ buf[n] = '\0';
+
+ char *extra_buf = bufs->extra.data;
+ idx_t end_idx;
+ if (end_in_extra_buffer)
+ end_idx = end - extra_buf;
+ size_t len = strlen (end);
+ if (INT_ADD_OVERFLOW (len, n))
+ xalloc_die ();
+ while (bufs->extra.length <= len + n)
+ {
+ if (!scratch_buffer_grow_preserve (&bufs->extra))
+ xalloc_die ();
+ extra_buf = bufs->extra.data;
+ }
+ if (end_in_extra_buffer)
+ end = extra_buf + end_idx;
+
+ /* Careful here, end may be a pointer into extra_buf... */
+ memmove (&extra_buf[n], end, len + 1);
+ name = end = memcpy (extra_buf, buf, n);
+ end_in_extra_buffer = true;
+
+ if (IS_ABSOLUTE_FILE_NAME (buf))
+ {
+ idx_t pfxlen = FILE_SYSTEM_PREFIX_LEN (buf);
+
+ dest = mempcpy (rname, buf, pfxlen);
+ *dest++ = '/'; /* It's an absolute symlink */
+ if (DOUBLE_SLASH_IS_DISTINCT_ROOT)
+ {
+ if (ISSLASH (buf[1]) && !ISSLASH (buf[2]) && !pfxlen)
+ *dest++ = '/';
+ *dest = '\0';
+ }
+ /* Install the new prefix to be in effect hereafter. */
+ prefix_len = pfxlen;
+ }
+ else
+ {
+ /* Back up to previous component, ignore if at root
+ already: */
+ if (dest > rname + prefix_len + 1)
+ for (--dest; dest > rname && !ISSLASH (dest[-1]); --dest)
+ continue;
+ if (DOUBLE_SLASH_IS_DISTINCT_ROOT && dest == rname + 1
+ && ISSLASH (*dest) && !ISSLASH (dest[1]) && !prefix_len)
+ dest++;
+ }
+ }
+ else if (! (can_exist == CAN_MISSING
+ || (suffix_requires_dir_check (end)
+ ? dir_check (rname, dest)
+ : !logical
+ ? errno == EINVAL
+ : *end || file_accessible (rname))
+ || (can_exist == CAN_ALL_BUT_LAST
+ && errno == ENOENT
+ && !end[strspn (end, SLASHES)])))
+ goto error;
+ }
+ }
+ if (dest > rname + prefix_len + 1 && ISSLASH (dest[-1]))
+ --dest;
+ if (DOUBLE_SLASH_IS_DISTINCT_ROOT && dest == rname + 1 && !prefix_len
+ && ISSLASH (*dest) && !ISSLASH (dest[1]))
+ dest++;
+ failed = false;
+
+error:
+ if (ht)
+ hash_free (ht);
+
+ if (failed)
+ return NULL;
+
+ *dest++ = '\0';
+ char *result = malloc (dest - rname);
+ if (!result)
+ xalloc_die ();
+ return memcpy (result, rname, dest - rname);
+}
+
+/* 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, depending 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)
+{
+ struct realpath_bufs bufs;
+ scratch_buffer_init (&bufs.rname);
+ scratch_buffer_init (&bufs.extra);
+ scratch_buffer_init (&bufs.link);
+ char *result = canonicalize_filename_mode_stk (name, can_mode, &bufs);
+ scratch_buffer_free (&bufs.link);
+ scratch_buffer_free (&bufs.extra);
+ scratch_buffer_free (&bufs.rname);
+ return result;
+}
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