| /* Return the canonical absolute name of a given file. |
| Copyright (C) 1996-2021 Free Software Foundation, Inc. |
| This file is part of the GNU C Library. |
| |
| The GNU C Library 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. |
| |
| The GNU C Library 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 the GNU C Library; if not, see |
| <https://www.gnu.org/licenses/>. */ |
| |
| #ifndef _LIBC |
| /* Don't use __attribute__ __nonnull__ in this compilation unit. Otherwise gcc |
| optimizes away the name == NULL test below. */ |
| # define _GL_ARG_NONNULL(params) |
| |
| # define _GL_USE_STDLIB_ALLOC 1 |
| # include <libc-config.h> |
| #endif |
| |
| /* Specification. */ |
| #include <stdlib.h> |
| |
| #include <errno.h> |
| #include <fcntl.h> |
| #include <limits.h> |
| #include <stdbool.h> |
| #include <string.h> |
| #include <sys/stat.h> |
| #include <unistd.h> |
| |
| #include <eloop-threshold.h> |
| #include <filename.h> |
| #include <idx.h> |
| #include <intprops.h> |
| #include <scratch_buffer.h> |
| |
| #ifdef _LIBC |
| # include <shlib-compat.h> |
| # define GCC_LINT 1 |
| # define _GL_ATTRIBUTE_PURE __attribute__ ((__pure__)) |
| #else |
| # define __canonicalize_file_name canonicalize_file_name |
| # define __realpath realpath |
| # include "pathmax.h" |
| # define __faccessat faccessat |
| # if defined _WIN32 && !defined __CYGWIN__ |
| # define __getcwd _getcwd |
| # elif HAVE_GETCWD |
| # if IN_RELOCWRAPPER |
| /* When building the relocatable program wrapper, use the system's getcwd |
| function, not the gnulib override, otherwise we would get a link error. |
| */ |
| # undef getcwd |
| # endif |
| # if defined VMS && !defined getcwd |
| /* We want the directory in Unix syntax, not in VMS syntax. |
| The gnulib override of 'getcwd' takes 2 arguments; the original VMS |
| 'getcwd' takes 3 arguments. */ |
| # define __getcwd(buf, max) getcwd (buf, max, 0) |
| # else |
| # define __getcwd getcwd |
| # endif |
| # else |
| # define __getcwd(buf, max) getwd (buf) |
| # endif |
| # define __mempcpy mempcpy |
| # define __pathconf pathconf |
| # define __rawmemchr rawmemchr |
| # define __readlink readlink |
| # define __stat stat |
| #endif |
| |
| /* Suppress bogus GCC -Wmaybe-uninitialized warnings. */ |
| #if defined GCC_LINT || defined lint |
| # define IF_LINT(Code) Code |
| #else |
| # define IF_LINT(Code) /* empty */ |
| #endif |
| |
| #ifndef DOUBLE_SLASH_IS_DISTINCT_ROOT |
| # define DOUBLE_SLASH_IS_DISTINCT_ROOT false |
| #endif |
| |
| #if defined _LIBC || !FUNC_REALPATH_WORKS |
| |
| /* Return true if FILE's existence can be shown, false (setting errno) |
| otherwise. Follow symbolic links. */ |
| static bool |
| file_accessible (char const *file) |
| { |
| # if defined _LIBC || 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 "/.". */ |
| |
| #if defined _LIBC || defined 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); |
| } |
| |
| static idx_t |
| get_path_max (void) |
| { |
| # ifdef PATH_MAX |
| long int path_max = PATH_MAX; |
| # else |
| /* The caller invoked realpath with a null RESOLVED, even though |
| PATH_MAX is not defined as a constant. The glibc manual says |
| programs should not do this, and POSIX says the behavior is undefined. |
| Historically, glibc here used the result of pathconf, or 1024 if that |
| failed; stay consistent with this (dubious) historical practice. */ |
| int err = errno; |
| long int path_max = __pathconf ("/", _PC_PATH_MAX); |
| __set_errno (err); |
| # endif |
| return path_max < 0 ? 1024 : path_max <= IDX_MAX ? path_max : IDX_MAX; |
| } |
| |
| /* Act like __realpath (see below), with an additional argument |
| rname_buf that can be used as temporary storage. |
| |
| If GCC_LINT is defined, do not inline this function with GCC 10.1 |
| and later, to avoid creating a pointer to the stack that GCC |
| -Wreturn-local-addr incorrectly complains about. See: |
| https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93644 |
| Although the noinline attribute can hurt performance a bit, no better way |
| to pacify GCC is known; even an explicit #pragma does not pacify GCC. |
| When the GCC bug is fixed this workaround should be limited to the |
| broken GCC versions. */ |
| #if __GNUC_PREREQ (10, 1) |
| # if defined GCC_LINT || defined lint |
| __attribute__ ((__noinline__)) |
| # elif __OPTIMIZE__ && !__NO_INLINE__ |
| # define GCC_BOGUS_WRETURN_LOCAL_ADDR |
| # endif |
| #endif |
| static char * |
| realpath_stk (const char *name, char *resolved, |
| struct scratch_buffer *rname_buf) |
| { |
| char *dest; |
| char const *start; |
| char const *end; |
| int num_links = 0; |
| |
| if (name == NULL) |
| { |
| /* As per Single Unix Specification V2 we must return an error if |
| either parameter is a null pointer. We extend this to allow |
| the RESOLVED parameter to be NULL in case the we are expected to |
| allocate the room for the return value. */ |
| __set_errno (EINVAL); |
| return NULL; |
| } |
| |
| if (name[0] == '\0') |
| { |
| /* As per Single Unix Specification V2 we must return an error if |
| the name argument points to an empty string. */ |
| __set_errno (ENOENT); |
| return NULL; |
| } |
| |
| struct scratch_buffer extra_buffer, link_buffer; |
| scratch_buffer_init (&extra_buffer); |
| scratch_buffer_init (&link_buffer); |
| scratch_buffer_init (rname_buf); |
| char *rname_on_stack = rname_buf->data; |
| char *rname = rname_on_stack; |
| 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 (rname, rname_buf->length)) |
| { |
| if (errno != ERANGE) |
| { |
| dest = rname; |
| goto error; |
| } |
| if (!scratch_buffer_grow (rname_buf)) |
| goto error_nomem; |
| rname = rname_buf->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++ = '/'; |
| *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 + rname_buf->length - dest |
| < startlen + sizeof dir_suffix) |
| { |
| idx_t dest_offset = dest - rname; |
| if (!scratch_buffer_grow_preserve (rname_buf)) |
| goto error_nomem; |
| rname = rname_buf->data; |
| dest = rname + dest_offset; |
| } |
| |
| dest = __mempcpy (dest, start, startlen); |
| *dest = '\0'; |
| |
| char *buf; |
| ssize_t n; |
| while (true) |
| { |
| buf = link_buffer.data; |
| idx_t bufsize = link_buffer.length; |
| n = __readlink (rname, buf, bufsize - 1); |
| if (n < bufsize - 1) |
| break; |
| if (!scratch_buffer_grow (&link_buffer)) |
| goto error_nomem; |
| } |
| if (0 <= n) |
| { |
| if (++num_links > __eloop_threshold ()) |
| { |
| __set_errno (ELOOP); |
| goto error; |
| } |
| |
| buf[n] = '\0'; |
| |
| char *extra_buf = extra_buffer.data; |
| idx_t end_idx IF_LINT (= 0); |
| if (end_in_extra_buffer) |
| end_idx = end - extra_buf; |
| size_t len = strlen (end); |
| if (INT_ADD_OVERFLOW (len, n)) |
| { |
| __set_errno (ENOMEM); |
| goto error_nomem; |
| } |
| while (extra_buffer.length <= len + n) |
| { |
| if (!scratch_buffer_grow_preserve (&extra_buffer)) |
| goto error_nomem; |
| extra_buf = extra_buffer.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 (! (suffix_requires_dir_check (end) |
| ? dir_check (rname, dest) |
| : errno == EINVAL)) |
| 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: |
| *dest++ = '\0'; |
| if (resolved != NULL && dest - rname <= get_path_max ()) |
| rname = strcpy (resolved, rname); |
| |
| error_nomem: |
| scratch_buffer_free (&extra_buffer); |
| scratch_buffer_free (&link_buffer); |
| |
| if (failed || rname == resolved) |
| { |
| scratch_buffer_free (rname_buf); |
| return failed ? NULL : resolved; |
| } |
| |
| return scratch_buffer_dupfree (rname_buf, dest - rname); |
| } |
| |
| /* 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 file name components must exist. If |
| RESOLVED is null, the result is malloc'd; otherwise, if the |
| canonical name is PATH_MAX chars or more, returns null with 'errno' |
| set to ENAMETOOLONG; if the name fits in fewer than PATH_MAX chars, |
| returns the name in RESOLVED. If the name cannot be resolved and |
| RESOLVED is non-NULL, it contains the name of the first component |
| that cannot be resolved. If the name can be resolved, RESOLVED |
| holds the same value as the value returned. */ |
| |
| char * |
| __realpath (const char *name, char *resolved) |
| { |
| #ifdef GCC_BOGUS_WRETURN_LOCAL_ADDR |
| #warning "GCC might issue a bogus -Wreturn-local-addr warning here." |
| #warning "See <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93644>." |
| #endif |
| struct scratch_buffer rname_buffer; |
| return realpath_stk (name, resolved, &rname_buffer); |
| } |
| libc_hidden_def (__realpath) |
| versioned_symbol (libc, __realpath, realpath, GLIBC_2_3); |
| #endif /* !FUNC_REALPATH_WORKS || defined _LIBC */ |
| |
| |
| #if SHLIB_COMPAT(libc, GLIBC_2_0, GLIBC_2_3) |
| char * |
| attribute_compat_text_section |
| __old_realpath (const char *name, char *resolved) |
| { |
| if (resolved == NULL) |
| { |
| __set_errno (EINVAL); |
| return NULL; |
| } |
| |
| return __realpath (name, resolved); |
| } |
| compat_symbol (libc, __old_realpath, realpath, GLIBC_2_0); |
| #endif |
| |
| |
| char * |
| __canonicalize_file_name (const char *name) |
| { |
| return __realpath (name, NULL); |
| } |
| weak_alias (__canonicalize_file_name, canonicalize_file_name) |
