1 /* Part of CPP library. (include file handling)
2 Copyright (C) 1986, 1987, 1989, 1992, 1993, 1994, 1995, 1998,
3 1999, 2000, 2001 Free Software Foundation, Inc.
4 Written by Per Bothner, 1994.
5 Based on CCCP program by Paul Rubin, June 1986
6 Adapted to ANSI C, Richard Stallman, Jan 1987
7 Split out of cpplib.c, Zack Weinberg, Oct 1998
9 This program is free software; you can redistribute it and/or modify it
10 under the terms of the GNU General Public License as published by the
11 Free Software Foundation; either version 2, or (at your option) any
14 This program is distributed in the hope that it will be useful,
15 but WITHOUT ANY WARRANTY; without even the implied warranty of
16 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 GNU General Public License for more details.
19 You should have received a copy of the GNU General Public License
20 along with this program; if not, write to the Free Software
21 Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
29 #include "splay-tree.h"
32 # include <sys/mman.h>
33 # ifndef MMAP_THRESHOLD
34 # define MMAP_THRESHOLD 3 /* Minimum page count to mmap the file. */
37 #else /* No MMAP_FILE */
38 # undef MMAP_THRESHOLD
39 # define MMAP_THRESHOLD 0
46 /* If errno is inspected immediately after a system call fails, it will be
47 nonzero, and no error number will ever be zero. */
55 /* Suppress warning about function macros used w/o arguments in traditional
56 C. It is unlikely that glibc's strcmp macro helps this file at all. */
59 /* This structure is used for the table of all includes. */
62 const char *name; /* actual path name of file */
63 const cpp_hashnode *cmacro; /* macro, if any, preventing reinclusion. */
64 const struct search_path *foundhere;
65 /* location in search path where file was
66 found, for #include_next and sysp. */
67 const unsigned char *buffer; /* pointer to cached file contents */
68 struct stat st; /* copy of stat(2) data for file */
69 int fd; /* fd open on file (short term storage only) */
70 int err_no; /* errno obtained if opening a file failed */
71 unsigned short include_count; /* number of times file has been read */
72 unsigned short refcnt; /* number of stacked buffers using this file */
73 unsigned char mapped; /* file buffer is mmapped */
76 /* The cmacro works like this: If it's NULL, the file is to be
77 included again. If it's NEVER_REREAD, the file is never to be
78 included again. Otherwise it is a macro hashnode, and the file is
79 to be included again if the macro is defined. */
80 #define NEVER_REREAD ((const cpp_hashnode *)-1)
81 #define DO_NOT_REREAD(inc) \
82 ((inc)->cmacro && ((inc)->cmacro == NEVER_REREAD \
83 || (inc)->cmacro->type == NT_MACRO))
84 #define NO_INCLUDE_PATH ((struct include_file *) -1)
86 static struct file_name_map *read_name_map
87 PARAMS ((cpp_reader *, const char *));
88 static char *read_filename_string PARAMS ((int, FILE *));
89 static char *remap_filename PARAMS ((cpp_reader *, char *,
90 struct search_path *));
91 static struct search_path *search_from PARAMS ((cpp_reader *,
93 static struct include_file *
94 find_include_file PARAMS ((cpp_reader *, const cpp_token *,
96 static struct include_file *open_file PARAMS ((cpp_reader *, const char *));
97 static int read_include_file PARAMS ((cpp_reader *, struct include_file *));
98 static bool stack_include_file PARAMS ((cpp_reader *, struct include_file *));
99 static void purge_cache PARAMS ((struct include_file *));
100 static void destroy_node PARAMS ((splay_tree_value));
101 static int report_missing_guard PARAMS ((splay_tree_node, void *));
102 static splay_tree_node find_or_create_entry PARAMS ((cpp_reader *,
104 static void handle_missing_header PARAMS ((cpp_reader *, const char *, int));
105 static int remove_component_p PARAMS ((const char *));
107 /* Set up the splay tree we use to store information about all the
108 file names seen in this compilation. We also have entries for each
109 file we tried to open but failed; this saves system calls since we
110 don't try to open it again in future.
112 The key of each node is the file name, after processing by
113 _cpp_simplify_pathname. The path name may or may not be absolute.
114 The path string has been malloced, as is automatically freed by
115 registering free () as the splay tree key deletion function.
117 A node's value is a pointer to a struct include_file, and is never
120 _cpp_init_includes (pfile)
123 pfile->all_include_files
124 = splay_tree_new ((splay_tree_compare_fn) strcmp,
125 (splay_tree_delete_key_fn) free,
129 /* Tear down the splay tree. */
131 _cpp_cleanup_includes (pfile)
134 splay_tree_delete (pfile->all_include_files);
137 /* Free a node. The path string is automatically freed. */
142 struct include_file *f = (struct include_file *)v;
151 /* Mark a file to not be reread (e.g. #import, read failure). */
153 _cpp_never_reread (file)
154 struct include_file *file;
156 file->cmacro = NEVER_REREAD;
159 /* Lookup a filename, which is simplified after making a copy, and
160 create an entry if none exists. errno is nonzero iff a (reported)
161 stat() error occurred during simplification. */
162 static splay_tree_node
163 find_or_create_entry (pfile, fname)
167 splay_tree_node node;
168 struct include_file *file;
169 char *name = xstrdup (fname);
171 _cpp_simplify_pathname (name);
172 node = splay_tree_lookup (pfile->all_include_files, (splay_tree_key) name);
177 file = xcnew (struct include_file);
179 file->err_no = errno;
180 node = splay_tree_insert (pfile->all_include_files,
181 (splay_tree_key) file->name,
182 (splay_tree_value) file);
188 /* Enter a file name in the splay tree, for the sake of cpp_included. */
190 _cpp_fake_include (pfile, fname)
194 find_or_create_entry (pfile, fname);
197 /* Given a file name, look it up in the cache; if there is no entry,
198 create one with a non-NULL value (regardless of success in opening
199 the file). If the file doesn't exist or is inaccessible, this
200 entry is flagged so we don't attempt to open it again in the
201 future. If the file isn't open, open it. The empty string is
202 interpreted as stdin.
204 Returns an include_file structure with an open file descriptor on
205 success, or NULL on failure. */
207 static struct include_file *
208 open_file (pfile, filename)
210 const char *filename;
212 splay_tree_node nd = find_or_create_entry (pfile, filename);
213 struct include_file *file = (struct include_file *) nd->value;
217 /* Ugh. handle_missing_header () needs errno to be set. */
218 errno = file->err_no;
222 /* Don't reopen an idempotent file. */
223 if (DO_NOT_REREAD (file))
226 /* Don't reopen one which is already loaded. */
227 if (file->buffer != NULL)
230 /* We used to open files in nonblocking mode, but that caused more
231 problems than it solved. Do take care not to acquire a
232 controlling terminal by mistake (this can't happen on sane
233 systems, but paranoia is a virtue).
235 Use the three-argument form of open even though we aren't
236 specifying O_CREAT, to defend against broken system headers.
238 O_BINARY tells some runtime libraries (notably DJGPP) not to do
239 newline translation; we can handle DOS line breaks just fine
242 Special case: the empty string is translated to stdin. */
244 if (filename[0] == '\0')
247 file->fd = open (file->name, O_RDONLY | O_NOCTTY | O_BINARY, 0666);
249 if (file->fd != -1 && fstat (file->fd, &file->st) == 0)
251 /* If it's a directory, we return null and continue the search
252 as the file we're looking for may appear elsewhere in the
254 if (S_ISDIR (file->st.st_mode))
258 /* Mark a regular, zero-length file never-reread now. */
259 if (S_ISREG (file->st.st_mode) && file->st.st_size == 0)
261 _cpp_never_reread (file);
270 /* Don't issue an error message if the file doesn't exist. */
271 file->err_no = errno;
272 if (errno != ENOENT && errno != ENOTDIR)
273 cpp_error_from_errno (pfile, file->name);
278 /* Place the file referenced by INC into a new buffer on the buffer
279 stack, unless there are errors, or the file is not re-included
280 because of e.g. multiple-include guards. Returns true if a buffer
284 stack_include_file (pfile, inc)
286 struct include_file *inc;
290 const char *filename;
292 if (DO_NOT_REREAD (inc))
295 sysp = MAX ((pfile->map ? pfile->map->sysp : 0),
296 (inc->foundhere ? inc->foundhere->sysp : 0));
298 /* For -M, add the file to the dependencies on its first inclusion. */
299 if (CPP_OPTION (pfile, print_deps) > sysp && !inc->include_count)
300 deps_add_dep (pfile->deps, inc->name);
305 /* If an error occurs, do not try to read this file again. */
306 if (read_include_file (pfile, inc))
308 _cpp_never_reread (inc);
316 /* We don't want MI guard advice for the main file. */
317 inc->include_count++;
320 fp = cpp_push_buffer (pfile, inc->buffer, inc->st.st_size, BUF_FILE, 0);
324 /* Initialise controlling macro state. */
325 pfile->mi_valid = true;
326 pfile->mi_cmacro = 0;
328 /* Generate the call back. */
329 filename = inc->name;
330 if (*filename == '\0')
331 filename = _("<stdin>");
332 _cpp_do_file_change (pfile, LC_ENTER, filename, 1, sysp);
337 /* Read the file referenced by INC into the file cache.
339 If fd points to a plain file, we might be able to mmap it; we can
340 definitely allocate the buffer all at once. If fd is a pipe or
341 terminal, we can't do either. If fd is something weird, like a
342 block device, we don't want to read it at all.
344 Unfortunately, different systems use different st.st_mode values
345 for pipes: some have S_ISFIFO, some S_ISSOCK, some are buggy and
346 zero the entire struct stat except a couple fields. Hence we don't
347 even try to figure out what something is, except for plain files
350 FIXME: Flush file cache and try again if we run out of memory. */
353 read_include_file (pfile, inc)
355 struct include_file *inc;
357 ssize_t size, offset, count;
360 static int pagesize = -1;
363 if (S_ISREG (inc->st.st_mode))
365 /* off_t might have a wider range than ssize_t - in other words,
366 the max size of a file might be bigger than the address
367 space. We can't handle a file that large. (Anyone with
368 a single source file bigger than 2GB needs to rethink
369 their coding style.) Some systems (e.g. AIX 4.1) define
370 SSIZE_MAX to be much smaller than the actual range of the
371 type. Use INTTYPE_MAXIMUM unconditionally to ensure this
373 if (inc->st.st_size > INTTYPE_MAXIMUM (ssize_t))
375 cpp_error (pfile, "%s is too large", inc->name);
378 size = inc->st.st_size;
383 pagesize = getpagesize ();
385 if (size / pagesize >= MMAP_THRESHOLD)
387 buf = (U_CHAR *) mmap (0, size, PROT_READ, MAP_PRIVATE, inc->fd, 0);
388 if (buf == (U_CHAR *)-1)
395 buf = (U_CHAR *) xmalloc (size);
397 while (offset < size)
399 count = read (inc->fd, buf + offset, size - offset);
404 cpp_warning (pfile, "%s is shorter than expected", inc->name);
411 else if (S_ISBLK (inc->st.st_mode))
413 cpp_error (pfile, "%s is a block device", inc->name);
418 /* 8 kilobytes is a sensible starting size. It ought to be
419 bigger than the kernel pipe buffer, and it's definitely
420 bigger than the majority of C source files. */
423 buf = (U_CHAR *) xmalloc (size);
425 while ((count = read (inc->fd, buf + offset, size - offset)) > 0)
429 buf = xrealloc (buf, (size *= 2));
435 buf = xrealloc (buf, offset);
436 inc->st.st_size = offset;
443 cpp_error_from_errno (pfile, inc->name);
450 struct include_file *inc;
456 munmap ((PTR) inc->buffer, inc->st.st_size);
459 free ((PTR) inc->buffer);
464 /* Return 1 if the file named by FNAME has been included before in
465 any context, 0 otherwise. */
467 cpp_included (pfile, fname)
471 struct search_path *path;
475 if (IS_ABSOLUTE_PATHNAME (fname))
477 /* Just look it up. */
478 nd = splay_tree_lookup (pfile->all_include_files, (splay_tree_key) fname);
479 return (nd && nd->value);
482 /* Search directory path for the file. */
483 name = (char *) alloca (strlen (fname) + pfile->max_include_len + 2);
484 for (path = CPP_OPTION (pfile, quote_include); path; path = path->next)
486 memcpy (name, path->name, path->len);
487 name[path->len] = '/';
488 strcpy (&name[path->len + 1], fname);
489 if (CPP_OPTION (pfile, remap))
490 n = remap_filename (pfile, name, path);
494 nd = splay_tree_lookup (pfile->all_include_files, (splay_tree_key) n);
501 /* Search for HEADER. Return 0 if there is no such file (or it's
502 un-openable), in which case an error code will be in errno. If
503 there is no include path to use it returns NO_INCLUDE_PATH,
504 otherwise an include_file structure. If this request originates
505 from a #include_next directive, set INCLUDE_NEXT to true. */
507 static struct include_file *
508 find_include_file (pfile, header, type)
510 const cpp_token *header;
511 enum include_type type;
513 const char *fname = (const char *) header->val.str.text;
514 struct search_path *path;
515 struct include_file *file;
518 if (IS_ABSOLUTE_PATHNAME (fname))
519 return open_file (pfile, fname);
521 /* For #include_next, skip in the search path past the dir in which
522 the current file was found, but if it was found via an absolute
523 path use the normal search logic. */
524 if (type == IT_INCLUDE_NEXT && pfile->buffer->inc->foundhere)
525 path = pfile->buffer->inc->foundhere->next;
526 else if (header->type == CPP_HEADER_NAME)
527 path = CPP_OPTION (pfile, bracket_include);
529 path = search_from (pfile, type);
533 cpp_error (pfile, "No include path in which to find %s", fname);
534 return NO_INCLUDE_PATH;
537 /* Search directory path for the file. */
538 name = (char *) alloca (strlen (fname) + pfile->max_include_len + 2);
539 for (; path; path = path->next)
541 memcpy (name, path->name, path->len);
542 name[path->len] = '/';
543 strcpy (&name[path->len + 1], fname);
544 if (CPP_OPTION (pfile, remap))
545 n = remap_filename (pfile, name, path);
549 file = open_file (pfile, n);
552 file->foundhere = path;
560 /* Not everyone who wants to set system-header-ness on a buffer can
561 see the details of a buffer. This is an exported interface because
562 fix-header needs it. */
564 cpp_make_system_header (pfile, syshdr, externc)
570 /* 1 = system header, 2 = system header to be treated as C. */
572 flags = 1 + (externc != 0);
573 _cpp_do_file_change (pfile, LC_RENAME, pfile->map->to_file,
574 SOURCE_LINE (pfile->map, pfile->line), flags);
577 /* Report on all files that might benefit from a multiple include guard.
580 _cpp_report_missing_guards (pfile)
584 splay_tree_foreach (pfile->all_include_files, report_missing_guard,
589 report_missing_guard (n, b)
593 struct include_file *f = (struct include_file *) n->value;
594 int *bannerp = (int *)b;
596 if (f && f->cmacro == 0 && f->include_count == 1)
600 fputs (_("Multiple include guards may be useful for:\n"), stderr);
603 fputs (f->name, stderr);
609 /* Create a dependency, or issue an error message as appropriate. */
611 handle_missing_header (pfile, fname, angle_brackets)
616 int print_dep = CPP_PRINT_DEPS(pfile) > (angle_brackets || pfile->map->sysp);
618 if (CPP_OPTION (pfile, print_deps_missing_files) && print_dep)
620 if (!angle_brackets || IS_ABSOLUTE_PATHNAME (fname))
621 deps_add_dep (pfile->deps, fname);
624 /* If requested as a system header, assume it belongs in
625 the first system header directory. */
626 struct search_path *ptr = CPP_OPTION (pfile, bracket_include);
628 int len = 0, fname_len = strlen (fname);
633 p = (char *) alloca (len + fname_len + 2);
636 memcpy (p, ptr->name, len);
639 memcpy (p + len, fname, fname_len + 1);
640 deps_add_dep (pfile->deps, p);
643 /* If -M was specified, then don't count this as an error, because
644 we can still produce correct output. Otherwise, we can't produce
645 correct output, because there may be dependencies we need inside
646 the missing file, and we don't know what directory this missing
647 file exists in. FIXME: Use a future cpp_diagnotic_with_errno ()
648 for both of these cases. */
649 else if (CPP_PRINT_DEPS (pfile) && ! print_dep)
650 cpp_warning (pfile, "%s: %s", fname, xstrerror (errno));
652 cpp_error_from_errno (pfile, fname);
655 /* Handles #include-family directives, and the command line -imacros
656 and -include. Returns true if a buffer was stacked. */
658 _cpp_execute_include (pfile, header, type)
660 const cpp_token *header;
661 enum include_type type;
663 bool stacked = false;
664 struct include_file *inc = find_include_file (pfile, header, type);
667 handle_missing_header (pfile, (const char *) header->val.str.text,
668 header->type == CPP_HEADER_NAME);
669 else if (inc != NO_INCLUDE_PATH)
671 stacked = stack_include_file (pfile, inc);
673 if (type == IT_IMPORT)
674 _cpp_never_reread (inc);
680 /* Locate HEADER, and determine whether it is newer than the current
681 file. If it cannot be located or dated, return -1, if it is newer
682 newer, return 1, otherwise 0. */
684 _cpp_compare_file_date (pfile, header)
686 const cpp_token *header;
688 struct include_file *inc = find_include_file (pfile, header, 0);
690 if (inc == NULL || inc == NO_INCLUDE_PATH)
699 return inc->st.st_mtime > pfile->buffer->inc->st.st_mtime;
703 /* Push an input buffer and load it up with the contents of FNAME. If
704 FNAME is "", read standard input. Return true if a buffer was
707 _cpp_read_file (pfile, fname)
711 struct include_file *f = open_file (pfile, fname);
712 bool stacked = false;
715 cpp_error_from_errno (pfile, fname);
717 stacked = stack_include_file (pfile, f);
722 /* Do appropriate cleanup when a file buffer is popped off the input
725 _cpp_pop_file_buffer (pfile, buf)
729 struct include_file *inc = buf->inc;
731 /* Record the inclusion-preventing macro, which could be NULL
732 meaning no controlling macro. */
733 if (pfile->mi_valid && inc->cmacro == NULL)
734 inc->cmacro = pfile->mi_cmacro;
736 /* Invalidate control macros in the #including file. */
737 pfile->mi_valid = false;
740 if (inc->refcnt == 0 && DO_NOT_REREAD (inc))
744 /* Returns the first place in the include chain to start searching for
745 "" includes. This involves stripping away the basename of the
746 current file, unless -I- was specified.
748 If we're handling -include or -imacros, use the "" chain, but with
749 the preprocessor's cwd prepended. */
750 static struct search_path *
751 search_from (pfile, type)
753 enum include_type type;
755 cpp_buffer *buffer = pfile->buffer;
758 /* Command line uses the cwd, and does not cache the result. */
759 if (type == IT_CMDLINE)
762 /* Ignore the current file's directory if -I- was given. */
763 if (CPP_OPTION (pfile, ignore_srcdir))
764 return CPP_OPTION (pfile, quote_include);
766 if (! buffer->search_cached)
768 buffer->search_cached = 1;
770 dlen = lbasename (buffer->inc->name) - buffer->inc->name;
774 /* We don't guarantee NAME is null-terminated. This saves
775 allocating and freeing memory, and duplicating it when faking
776 buffers in cpp_push_buffer. Drop a trailing '/'. */
777 buffer->dir.name = buffer->inc->name;
784 buffer->dir.name = ".";
788 if (dlen > pfile->max_include_len)
789 pfile->max_include_len = dlen;
791 buffer->dir.len = dlen;
792 buffer->dir.next = CPP_OPTION (pfile, quote_include);
793 buffer->dir.sysp = pfile->map->sysp;
799 /* The file_name_map structure holds a mapping of file names for a
800 particular directory. This mapping is read from the file named
801 FILE_NAME_MAP_FILE in that directory. Such a file can be used to
802 map filenames on a file system with severe filename restrictions,
803 such as DOS. The format of the file name map file is just a series
804 of lines with two tokens on each line. The first token is the name
805 to map, and the second token is the actual name to use. */
809 struct file_name_map *map_next;
814 #define FILE_NAME_MAP_FILE "header.gcc"
816 /* Read a space delimited string of unlimited length from a stdio
820 read_filename_string (ch, f)
828 set = alloc = xmalloc (len + 1);
832 while ((ch = getc (f)) != EOF && ! is_space(ch))
834 if (set - alloc == len)
837 alloc = xrealloc (alloc, len + 1);
838 set = alloc + len / 2;
848 /* This structure holds a linked list of file name maps, one per directory. */
850 struct file_name_map_list
852 struct file_name_map_list *map_list_next;
854 struct file_name_map *map_list_map;
857 /* Read the file name map file for DIRNAME. */
859 static struct file_name_map *
860 read_name_map (pfile, dirname)
864 register struct file_name_map_list *map_list_ptr;
868 /* Check the cache of directories, and mappings in their remap file. */
869 for (map_list_ptr = CPP_OPTION (pfile, map_list); map_list_ptr;
870 map_list_ptr = map_list_ptr->map_list_next)
871 if (! strcmp (map_list_ptr->map_list_name, dirname))
872 return map_list_ptr->map_list_map;
874 map_list_ptr = ((struct file_name_map_list *)
875 xmalloc (sizeof (struct file_name_map_list)));
876 map_list_ptr->map_list_name = xstrdup (dirname);
878 /* The end of the list ends in NULL. */
879 map_list_ptr->map_list_map = NULL;
881 name = (char *) alloca (strlen (dirname) + strlen (FILE_NAME_MAP_FILE) + 2);
882 strcpy (name, dirname);
885 strcat (name, FILE_NAME_MAP_FILE);
886 f = fopen (name, "r");
888 /* Silently return NULL if we cannot open. */
892 int dirlen = strlen (dirname);
894 while ((ch = getc (f)) != EOF)
897 struct file_name_map *ptr;
901 from = read_filename_string (ch, f);
902 while ((ch = getc (f)) != EOF && is_hspace(ch))
904 to = read_filename_string (ch, f);
906 ptr = ((struct file_name_map *)
907 xmalloc (sizeof (struct file_name_map)));
908 ptr->map_from = from;
910 /* Make the real filename absolute. */
911 if (IS_ABSOLUTE_PATHNAME (to))
915 ptr->map_to = xmalloc (dirlen + strlen (to) + 2);
916 strcpy (ptr->map_to, dirname);
917 ptr->map_to[dirlen] = '/';
918 strcpy (ptr->map_to + dirlen + 1, to);
922 ptr->map_next = map_list_ptr->map_list_map;
923 map_list_ptr->map_list_map = ptr;
925 while ((ch = getc (f)) != '\n')
932 /* Add this information to the cache. */
933 map_list_ptr->map_list_next = CPP_OPTION (pfile, map_list);
934 CPP_OPTION (pfile, map_list) = map_list_ptr;
936 return map_list_ptr->map_list_map;
939 /* Remap an unsimplified path NAME based on the file_name_map (if any)
942 remap_filename (pfile, name, loc)
945 struct search_path *loc;
947 struct file_name_map *map;
948 const char *from, *p;
953 /* Get a null-terminated path. */
954 char *dname = alloca (loc->len + 1);
955 memcpy (dname, loc->name, loc->len);
956 dname[loc->len] = '\0';
958 loc->name_map = read_name_map (pfile, dname);
963 /* This works since NAME has not been simplified yet. */
964 from = name + loc->len + 1;
966 for (map = loc->name_map; map; map = map->map_next)
967 if (!strcmp (map->map_from, from))
970 /* Try to find a mapping file for the particular directory we are
971 looking in. Thus #include <sys/types.h> will look up sys/types.h
972 in /usr/include/header.gcc and look up types.h in
973 /usr/include/sys/header.gcc. */
974 p = strrchr (name, '/');
978 /* We know p != name as absolute paths don't call remap_filename. */
980 cpp_ice (pfile, "absolute file name in remap_filename");
982 dir = (char *) alloca (p - name + 1);
983 memcpy (dir, name, p - name);
984 dir[p - name] = '\0';
987 for (map = read_name_map (pfile, dir); map; map = map->map_next)
988 if (! strcmp (map->map_from, from))
994 /* Returns true if it is safe to remove the final component of path,
995 when it is followed by a ".." component. We use lstat to avoid
996 symlinks if we have it. If not, we can still catch errors with
999 remove_component_p (path)
1006 result = lstat (path, &s);
1008 result = stat (path, &s);
1011 /* There's no guarantee that errno will be unchanged, even on
1012 success. Cygwin's lstat(), for example, will often set errno to
1013 ENOSYS. In case of success, reset errno to zero. */
1017 return result == 0 && S_ISDIR (s.st_mode);
1020 /* Simplify a path name in place, deleting redundant components. This
1021 reduces OS overhead and guarantees that equivalent paths compare
1022 the same (modulo symlinks).
1025 foo/bar/../quux foo/quux
1029 //quux //quux (POSIX allows leading // as a namespace escape)
1031 Guarantees no trailing slashes. All transforms reduce the length
1032 of the string. Returns PATH. errno is 0 if no error occurred;
1033 nonzero if an error occurred when using stat () or lstat (). */
1036 _cpp_simplify_pathname (path)
1041 char *base, *orig_base;
1045 /* Don't overflow the empty path by putting a '.' in it below. */
1049 #if defined (HAVE_DOS_BASED_FILE_SYSTEM)
1050 /* Convert all backslashes to slashes. */
1051 for (from = path; *from; from++)
1052 if (*from == '\\') *from = '/';
1054 /* Skip over leading drive letter if present. */
1055 if (ISALPHA (path[0]) && path[1] == ':')
1056 from = to = &path[2];
1063 /* Remove redundant leading /s. */
1072 /* 3 or more initial /s are equivalent to 1 /. */
1073 while (*++from == '/');
1075 /* On some hosts // differs from /; Posix allows this. */
1080 base = orig_base = to;
1085 while (*from == '/')
1093 if (from[1] == '\0')
1100 else if (from[1] == '.' && (from[2] == '/' || from[2] == '\0'))
1102 /* Don't simplify if there was no previous component. */
1103 if (absolute && orig_base == to)
1108 /* Don't simplify if the previous component was "../",
1109 or if an error has already occurred with (l)stat. */
1110 if (base != to && errno == 0)
1112 /* We don't back up if it's a symlink. */
1114 if (remove_component_p (path))
1116 while (to > base && *to != '/')
1126 /* Add the component separator. */
1130 /* Copy this component until the trailing null or '/'. */
1131 while (*from != '\0' && *from != '/')
1138 /* Change the empty string to "." so that it is not treated as stdin.