blob: 2578288e8acef49d0f4ac624fdc81dfbff7befce [file] [log] [blame]
/* Libiberty realpath. Like realpath, but more consistent behavior.
Based on gdb_realpath from GDB.
Copyright (C) 2003-2023 Free Software Foundation, Inc.
This file is part of the libiberty library.
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 2 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, write to the Free Software
Foundation, Inc., 51 Franklin Street - Fifth Floor,
Boston, MA 02110-1301, USA. */
/*
@deftypefn Replacement {const char*} lrealpath (const char *@var{name})
Given a pointer to a string containing a pathname, returns a canonical
version of the filename. Symlinks will be resolved, and ``.'' and ``..''
components will be simplified. The returned value will be allocated using
@code{malloc}, or @code{NULL} will be returned on a memory allocation error.
@end deftypefn
*/
#include "config.h"
#include "ansidecl.h"
#include "libiberty.h"
#ifdef HAVE_LIMITS_H
#include <limits.h>
#endif
#ifdef HAVE_STDLIB_H
#include <stdlib.h>
#endif
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif
#ifdef HAVE_STRING_H
#include <string.h>
#endif
/* On GNU libc systems the declaration is only visible with _GNU_SOURCE. */
#if defined(HAVE_CANONICALIZE_FILE_NAME) \
&& defined(NEED_DECLARATION_CANONICALIZE_FILE_NAME)
extern char *canonicalize_file_name (const char *);
#endif
#if defined(HAVE_REALPATH)
# if defined (PATH_MAX)
# define REALPATH_LIMIT PATH_MAX
# else
# if defined (MAXPATHLEN)
# define REALPATH_LIMIT MAXPATHLEN
# endif
# endif
#else
/* cygwin has realpath, so it won't get here. */
# if defined (_WIN32)
# define WIN32_LEAN_AND_MEAN
# include <windows.h> /* for GetFullPathName/GetFinalPathNameByHandle/
CreateFile/CloseHandle */
# define WIN32_REPLACE_SLASHES(_ptr, _len) \
for (unsigned i = 0; i != (_len); ++i) \
if ((_ptr)[i] == '\\') (_ptr)[i] = '/';
# define WIN32_UNC_PREFIX "//?/UNC/"
# define WIN32_UNC_PREFIX_LEN (sizeof(WIN32_UNC_PREFIX)-1)
# define WIN32_IS_UNC_PREFIX(ptr) \
(0 == memcmp(ptr, WIN32_UNC_PREFIX, WIN32_UNC_PREFIX_LEN))
# define WIN32_NON_UNC_PREFIX "//?/"
# define WIN32_NON_UNC_PREFIX_LEN (sizeof(WIN32_NON_UNC_PREFIX)-1)
# define WIN32_IS_NON_UNC_PREFIX(ptr) \
(0 == memcmp(ptr, WIN32_NON_UNC_PREFIX, WIN32_NON_UNC_PREFIX_LEN))
/* Get full path name without symlinks resolution.
It also converts all forward slashes to back slashes.
*/
char* get_full_path_name(const char *filename) {
DWORD len;
char *buf, *ptr, *res;
/* determining the required buffer size.
from the man: `If the lpBuffer buffer is too small to contain
the path, the return value is the size, in TCHARs, of the buffer
that is required to hold the path _and_the_terminating_null_character_`
*/
len = GetFullPathName(filename, 0, NULL, NULL);
if ( len == 0 )
return strdup(filename);
buf = (char *)malloc(len);
/* no point to check the result again */
len = GetFullPathName(filename, len, buf, NULL);
buf[len] = 0;
/* replace slashes */
WIN32_REPLACE_SLASHES(buf, len);
/* calculate offset based on prefix type */
len = WIN32_IS_UNC_PREFIX(buf)
? (WIN32_UNC_PREFIX_LEN - 2)
: WIN32_IS_NON_UNC_PREFIX(buf)
? WIN32_NON_UNC_PREFIX_LEN
: 0
;
ptr = buf + len;
if ( WIN32_IS_UNC_PREFIX(buf) ) {
ptr[0] = '/';
ptr[1] = '/';
}
res = strdup(ptr);
free(buf);
return res;
}
# if _WIN32_WINNT >= 0x0600
/* Get full path name WITH symlinks resolution.
It also converts all forward slashes to back slashes.
*/
char* get_final_path_name(HANDLE fh) {
DWORD len;
char *buf, *ptr, *res;
/* determining the required buffer size.
from the man: `If the function fails because lpszFilePath is too
small to hold the string plus the terminating null character,
the return value is the required buffer size, in TCHARs. This
value _includes_the_size_of_the_terminating_null_character_`.
but in my testcase I have path with 26 chars, the function
returns 26 also, ie without the trailing zero-char...
*/
len = GetFinalPathNameByHandle(
fh
,NULL
,0
,FILE_NAME_NORMALIZED | VOLUME_NAME_DOS
);
if ( len == 0 )
return NULL;
len += 1; /* for zero-char */
buf = (char *)malloc(len);
/* no point to check the result again */
len = GetFinalPathNameByHandle(
fh
,buf
,len
,FILE_NAME_NORMALIZED | VOLUME_NAME_DOS
);
buf[len] = 0;
/* replace slashes */
WIN32_REPLACE_SLASHES(buf, len);
/* calculate offset based on prefix type */
len = WIN32_IS_UNC_PREFIX(buf)
? (WIN32_UNC_PREFIX_LEN - 2)
: WIN32_IS_NON_UNC_PREFIX(buf)
? WIN32_NON_UNC_PREFIX_LEN
: 0
;
ptr = buf + len;
if ( WIN32_IS_UNC_PREFIX(buf) ) {
ptr[0] = '/';
ptr[1] = '/';
}
res = strdup(ptr);
free(buf);
return res;
}
# endif // _WIN32_WINNT >= 0x0600
# endif // _WIN32
#endif
char *
lrealpath (const char *filename)
{
/* Method 1: The system has a compile time upper bound on a filename
path. Use that and realpath() to canonicalize the name. This is
the most common case. Note that, if there isn't a compile time
upper bound, you want to avoid realpath() at all costs. */
#if defined(REALPATH_LIMIT)
{
char buf[REALPATH_LIMIT];
const char *rp = realpath (filename, buf);
if (rp == NULL)
rp = filename;
return strdup (rp);
}
#endif /* REALPATH_LIMIT */
/* Method 2: The host system (i.e., GNU) has the function
canonicalize_file_name() which malloc's a chunk of memory and
returns that, use that. */
#if defined(HAVE_CANONICALIZE_FILE_NAME)
{
char *rp = canonicalize_file_name (filename);
if (rp == NULL)
return strdup (filename);
else
return rp;
}
#endif
/* Method 3: Now we're getting desperate! The system doesn't have a
compile time buffer size and no alternative function. Query the
OS, using pathconf(), for the buffer limit. Care is needed
though, some systems do not limit PATH_MAX (return -1 for
pathconf()) making it impossible to pass a correctly sized buffer
to realpath() (it could always overflow). On those systems, we
skip this. */
#if defined (HAVE_REALPATH) && defined (HAVE_UNISTD_H)
{
/* Find out the max path size. */
long path_max = pathconf ("/", _PC_PATH_MAX);
if (path_max > 0)
{
/* PATH_MAX is bounded. */
char *buf, *rp, *ret;
buf = (char *) malloc (path_max);
if (buf == NULL)
return NULL;
rp = realpath (filename, buf);
ret = strdup (rp ? rp : filename);
free (buf);
return ret;
}
}
#endif
/* The MS Windows method */
#if defined (_WIN32)
{
char *res;
/* For Windows Vista and greater */
#if _WIN32_WINNT >= 0x0600
/* For some reason the function receives just empty `filename`, but not NULL.
What should we do in that case?
According to `strdup()` implementation
(https://elixir.bootlin.com/glibc/latest/source/string/strdup.c)
it will alloc 1 byte even for empty but non NULL string.
OK, will use `strdup()` for that case.
*/
if ( 0 == strlen(filename) )
return strdup(filename);
HANDLE fh = CreateFile(
filename
,FILE_READ_ATTRIBUTES
,FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE
,NULL
,OPEN_EXISTING
,FILE_FLAG_BACKUP_SEMANTICS
,NULL
);
if ( fh == INVALID_HANDLE_VALUE ) {
res = get_full_path_name(filename);
} else {
res = get_final_path_name(fh);
CloseHandle(fh);
if ( !res )
res = get_full_path_name(filename);
}
#else
/* For Windows XP */
res = get_full_path_name(filename);
#endif // _WIN32_WINNT >= 0x0600
return res;
}
#endif // _WIN32
}