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,
321 /* from_stage3 */ CPP_OPTION (pfile, preprocessed), 0);
325 /* Initialise controlling macro state. */
326 pfile->mi_valid = true;
327 pfile->mi_cmacro = 0;
329 /* Generate the call back. */
330 filename = inc->name;
331 if (*filename == '\0')
332 filename = _("<stdin>");
333 _cpp_do_file_change (pfile, LC_ENTER, filename, 1, sysp);
338 /* Read the file referenced by INC into the file cache.
340 If fd points to a plain file, we might be able to mmap it; we can
341 definitely allocate the buffer all at once. If fd is a pipe or
342 terminal, we can't do either. If fd is something weird, like a
343 block device, we don't want to read it at all.
345 Unfortunately, different systems use different st.st_mode values
346 for pipes: some have S_ISFIFO, some S_ISSOCK, some are buggy and
347 zero the entire struct stat except a couple fields. Hence we don't
348 even try to figure out what something is, except for plain files
351 FIXME: Flush file cache and try again if we run out of memory. */
354 read_include_file (pfile, inc)
356 struct include_file *inc;
358 ssize_t size, offset, count;
361 static int pagesize = -1;
364 if (S_ISREG (inc->st.st_mode))
366 /* off_t might have a wider range than ssize_t - in other words,
367 the max size of a file might be bigger than the address
368 space. We can't handle a file that large. (Anyone with
369 a single source file bigger than 2GB needs to rethink
370 their coding style.) Some systems (e.g. AIX 4.1) define
371 SSIZE_MAX to be much smaller than the actual range of the
372 type. Use INTTYPE_MAXIMUM unconditionally to ensure this
374 if (inc->st.st_size > INTTYPE_MAXIMUM (ssize_t))
376 cpp_error (pfile, "%s is too large", inc->name);
379 size = inc->st.st_size;
384 pagesize = getpagesize ();
386 if (size / pagesize >= MMAP_THRESHOLD)
388 buf = (U_CHAR *) mmap (0, size, PROT_READ, MAP_PRIVATE, inc->fd, 0);
389 if (buf == (U_CHAR *)-1)
396 buf = (U_CHAR *) xmalloc (size);
398 while (offset < size)
400 count = read (inc->fd, buf + offset, size - offset);
405 cpp_warning (pfile, "%s is shorter than expected", inc->name);
412 else if (S_ISBLK (inc->st.st_mode))
414 cpp_error (pfile, "%s is a block device", inc->name);
419 /* 8 kilobytes is a sensible starting size. It ought to be
420 bigger than the kernel pipe buffer, and it's definitely
421 bigger than the majority of C source files. */
424 buf = (U_CHAR *) xmalloc (size);
426 while ((count = read (inc->fd, buf + offset, size - offset)) > 0)
430 buf = xrealloc (buf, (size *= 2));
436 buf = xrealloc (buf, offset);
437 inc->st.st_size = offset;
444 cpp_error_from_errno (pfile, inc->name);
451 struct include_file *inc;
457 munmap ((PTR) inc->buffer, inc->st.st_size);
460 free ((PTR) inc->buffer);
465 /* Return 1 if the file named by FNAME has been included before in
466 any context, 0 otherwise. */
468 cpp_included (pfile, fname)
472 struct search_path *path;
476 if (IS_ABSOLUTE_PATHNAME (fname))
478 /* Just look it up. */
479 nd = splay_tree_lookup (pfile->all_include_files, (splay_tree_key) fname);
480 return (nd && nd->value);
483 /* Search directory path for the file. */
484 name = (char *) alloca (strlen (fname) + pfile->max_include_len + 2);
485 for (path = CPP_OPTION (pfile, quote_include); path; path = path->next)
487 memcpy (name, path->name, path->len);
488 name[path->len] = '/';
489 strcpy (&name[path->len + 1], fname);
490 if (CPP_OPTION (pfile, remap))
491 n = remap_filename (pfile, name, path);
495 nd = splay_tree_lookup (pfile->all_include_files, (splay_tree_key) n);
502 /* Search for HEADER. Return 0 if there is no such file (or it's
503 un-openable), in which case an error code will be in errno. If
504 there is no include path to use it returns NO_INCLUDE_PATH,
505 otherwise an include_file structure. If this request originates
506 from a #include_next directive, set INCLUDE_NEXT to true. */
508 static struct include_file *
509 find_include_file (pfile, header, type)
511 const cpp_token *header;
512 enum include_type type;
514 const char *fname = (const char *) header->val.str.text;
515 struct search_path *path;
516 struct include_file *file;
519 if (IS_ABSOLUTE_PATHNAME (fname))
520 return open_file (pfile, fname);
522 /* For #include_next, skip in the search path past the dir in which
523 the current file was found, but if it was found via an absolute
524 path use the normal search logic. */
525 if (type == IT_INCLUDE_NEXT && pfile->buffer->inc->foundhere)
526 path = pfile->buffer->inc->foundhere->next;
527 else if (header->type == CPP_HEADER_NAME)
528 path = CPP_OPTION (pfile, bracket_include);
530 path = search_from (pfile, type);
534 cpp_error (pfile, "No include path in which to find %s", fname);
535 return NO_INCLUDE_PATH;
538 /* Search directory path for the file. */
539 name = (char *) alloca (strlen (fname) + pfile->max_include_len + 2);
540 for (; path; path = path->next)
542 memcpy (name, path->name, path->len);
543 name[path->len] = '/';
544 strcpy (&name[path->len + 1], fname);
545 if (CPP_OPTION (pfile, remap))
546 n = remap_filename (pfile, name, path);
550 file = open_file (pfile, n);
553 file->foundhere = path;
561 /* Not everyone who wants to set system-header-ness on a buffer can
562 see the details of a buffer. This is an exported interface because
563 fix-header needs it. */
565 cpp_make_system_header (pfile, syshdr, externc)
571 /* 1 = system header, 2 = system header to be treated as C. */
573 flags = 1 + (externc != 0);
574 _cpp_do_file_change (pfile, LC_RENAME, pfile->map->to_file,
575 SOURCE_LINE (pfile->map, pfile->line), flags);
578 /* Report on all files that might benefit from a multiple include guard.
581 _cpp_report_missing_guards (pfile)
585 splay_tree_foreach (pfile->all_include_files, report_missing_guard,
590 report_missing_guard (n, b)
594 struct include_file *f = (struct include_file *) n->value;
595 int *bannerp = (int *)b;
597 if (f && f->cmacro == 0 && f->include_count == 1)
601 fputs (_("Multiple include guards may be useful for:\n"), stderr);
604 fputs (f->name, stderr);
610 /* Create a dependency, or issue an error message as appropriate. */
612 handle_missing_header (pfile, fname, angle_brackets)
617 int print_dep = CPP_PRINT_DEPS(pfile) > (angle_brackets || pfile->map->sysp);
619 if (CPP_OPTION (pfile, print_deps_missing_files) && print_dep)
621 if (!angle_brackets || IS_ABSOLUTE_PATHNAME (fname))
622 deps_add_dep (pfile->deps, fname);
625 /* If requested as a system header, assume it belongs in
626 the first system header directory. */
627 struct search_path *ptr = CPP_OPTION (pfile, bracket_include);
629 int len = 0, fname_len = strlen (fname);
634 p = (char *) alloca (len + fname_len + 2);
637 memcpy (p, ptr->name, len);
640 memcpy (p + len, fname, fname_len + 1);
641 deps_add_dep (pfile->deps, p);
644 /* If -M was specified, then don't count this as an error, because
645 we can still produce correct output. Otherwise, we can't produce
646 correct output, because there may be dependencies we need inside
647 the missing file, and we don't know what directory this missing
648 file exists in. FIXME: Use a future cpp_diagnotic_with_errno ()
649 for both of these cases. */
650 else if (CPP_PRINT_DEPS (pfile) && ! print_dep)
651 cpp_warning (pfile, "%s: %s", fname, xstrerror (errno));
653 cpp_error_from_errno (pfile, fname);
656 /* Handles #include-family directives, and the command line -imacros
657 and -include. Returns true if a buffer was stacked. */
659 _cpp_execute_include (pfile, header, type)
661 const cpp_token *header;
662 enum include_type type;
664 bool stacked = false;
665 struct include_file *inc = find_include_file (pfile, header, type);
668 handle_missing_header (pfile, (const char *) header->val.str.text,
669 header->type == CPP_HEADER_NAME);
670 else if (inc != NO_INCLUDE_PATH)
672 stacked = stack_include_file (pfile, inc);
674 if (type == IT_IMPORT)
675 _cpp_never_reread (inc);
681 /* Locate HEADER, and determine whether it is newer than the current
682 file. If it cannot be located or dated, return -1, if it is newer
683 newer, return 1, otherwise 0. */
685 _cpp_compare_file_date (pfile, header)
687 const cpp_token *header;
689 struct include_file *inc = find_include_file (pfile, header, 0);
691 if (inc == NULL || inc == NO_INCLUDE_PATH)
700 return inc->st.st_mtime > pfile->buffer->inc->st.st_mtime;
704 /* Push an input buffer and load it up with the contents of FNAME. If
705 FNAME is "", read standard input. Return true if a buffer was
708 _cpp_read_file (pfile, fname)
712 struct include_file *f = open_file (pfile, fname);
713 bool stacked = false;
716 cpp_error_from_errno (pfile, fname);
718 stacked = stack_include_file (pfile, f);
723 /* Do appropriate cleanup when a file buffer is popped off the input
724 stack. Push the next -include file, if any remain. */
726 _cpp_pop_file_buffer (pfile, inc)
728 struct include_file *inc;
730 /* Record the inclusion-preventing macro, which could be NULL
731 meaning no controlling macro. */
732 if (pfile->mi_valid && inc->cmacro == NULL)
733 inc->cmacro = pfile->mi_cmacro;
735 /* Invalidate control macros in the #including file. */
736 pfile->mi_valid = false;
739 if (inc->refcnt == 0 && DO_NOT_REREAD (inc))
742 /* Don't generate a callback for popping the main file. */
745 _cpp_do_file_change (pfile, LC_LEAVE, 0, 0, 0);
747 /* Finally, push the next -included file, if any. */
748 if (!pfile->buffer->prev)
749 _cpp_push_next_buffer (pfile);
753 /* Returns the first place in the include chain to start searching for
754 "" includes. This involves stripping away the basename of the
755 current file, unless -I- was specified.
757 If we're handling -include or -imacros, use the "" chain, but with
758 the preprocessor's cwd prepended. */
759 static struct search_path *
760 search_from (pfile, type)
762 enum include_type type;
764 cpp_buffer *buffer = pfile->buffer;
767 /* Command line uses the cwd, and does not cache the result. */
768 if (type == IT_CMDLINE)
771 /* Ignore the current file's directory if -I- was given. */
772 if (CPP_OPTION (pfile, ignore_srcdir))
773 return CPP_OPTION (pfile, quote_include);
775 if (! buffer->search_cached)
777 buffer->search_cached = 1;
779 dlen = lbasename (buffer->inc->name) - buffer->inc->name;
783 /* We don't guarantee NAME is null-terminated. This saves
784 allocating and freeing memory. Drop a trailing '/'. */
785 buffer->dir.name = buffer->inc->name;
792 buffer->dir.name = ".";
796 if (dlen > pfile->max_include_len)
797 pfile->max_include_len = dlen;
799 buffer->dir.len = dlen;
800 buffer->dir.next = CPP_OPTION (pfile, quote_include);
801 buffer->dir.sysp = pfile->map->sysp;
807 /* The file_name_map structure holds a mapping of file names for a
808 particular directory. This mapping is read from the file named
809 FILE_NAME_MAP_FILE in that directory. Such a file can be used to
810 map filenames on a file system with severe filename restrictions,
811 such as DOS. The format of the file name map file is just a series
812 of lines with two tokens on each line. The first token is the name
813 to map, and the second token is the actual name to use. */
817 struct file_name_map *map_next;
822 #define FILE_NAME_MAP_FILE "header.gcc"
824 /* Read a space delimited string of unlimited length from a stdio
828 read_filename_string (ch, f)
836 set = alloc = xmalloc (len + 1);
840 while ((ch = getc (f)) != EOF && ! is_space(ch))
842 if (set - alloc == len)
845 alloc = xrealloc (alloc, len + 1);
846 set = alloc + len / 2;
856 /* This structure holds a linked list of file name maps, one per directory. */
858 struct file_name_map_list
860 struct file_name_map_list *map_list_next;
862 struct file_name_map *map_list_map;
865 /* Read the file name map file for DIRNAME. */
867 static struct file_name_map *
868 read_name_map (pfile, dirname)
872 register struct file_name_map_list *map_list_ptr;
876 /* Check the cache of directories, and mappings in their remap file. */
877 for (map_list_ptr = CPP_OPTION (pfile, map_list); map_list_ptr;
878 map_list_ptr = map_list_ptr->map_list_next)
879 if (! strcmp (map_list_ptr->map_list_name, dirname))
880 return map_list_ptr->map_list_map;
882 map_list_ptr = ((struct file_name_map_list *)
883 xmalloc (sizeof (struct file_name_map_list)));
884 map_list_ptr->map_list_name = xstrdup (dirname);
886 /* The end of the list ends in NULL. */
887 map_list_ptr->map_list_map = NULL;
889 name = (char *) alloca (strlen (dirname) + strlen (FILE_NAME_MAP_FILE) + 2);
890 strcpy (name, dirname);
893 strcat (name, FILE_NAME_MAP_FILE);
894 f = fopen (name, "r");
896 /* Silently return NULL if we cannot open. */
900 int dirlen = strlen (dirname);
902 while ((ch = getc (f)) != EOF)
905 struct file_name_map *ptr;
909 from = read_filename_string (ch, f);
910 while ((ch = getc (f)) != EOF && is_hspace(ch))
912 to = read_filename_string (ch, f);
914 ptr = ((struct file_name_map *)
915 xmalloc (sizeof (struct file_name_map)));
916 ptr->map_from = from;
918 /* Make the real filename absolute. */
919 if (IS_ABSOLUTE_PATHNAME (to))
923 ptr->map_to = xmalloc (dirlen + strlen (to) + 2);
924 strcpy (ptr->map_to, dirname);
925 ptr->map_to[dirlen] = '/';
926 strcpy (ptr->map_to + dirlen + 1, to);
930 ptr->map_next = map_list_ptr->map_list_map;
931 map_list_ptr->map_list_map = ptr;
933 while ((ch = getc (f)) != '\n')
940 /* Add this information to the cache. */
941 map_list_ptr->map_list_next = CPP_OPTION (pfile, map_list);
942 CPP_OPTION (pfile, map_list) = map_list_ptr;
944 return map_list_ptr->map_list_map;
947 /* Remap an unsimplified path NAME based on the file_name_map (if any)
950 remap_filename (pfile, name, loc)
953 struct search_path *loc;
955 struct file_name_map *map;
956 const char *from, *p;
961 /* Get a null-terminated path. */
962 char *dname = alloca (loc->len + 1);
963 memcpy (dname, loc->name, loc->len);
964 dname[loc->len] = '\0';
966 loc->name_map = read_name_map (pfile, dname);
971 /* This works since NAME has not been simplified yet. */
972 from = name + loc->len + 1;
974 for (map = loc->name_map; map; map = map->map_next)
975 if (!strcmp (map->map_from, from))
978 /* Try to find a mapping file for the particular directory we are
979 looking in. Thus #include <sys/types.h> will look up sys/types.h
980 in /usr/include/header.gcc and look up types.h in
981 /usr/include/sys/header.gcc. */
982 p = strrchr (name, '/');
986 /* We know p != name as absolute paths don't call remap_filename. */
988 cpp_ice (pfile, "absolute file name in remap_filename");
990 dir = (char *) alloca (p - name + 1);
991 memcpy (dir, name, p - name);
992 dir[p - name] = '\0';
995 for (map = read_name_map (pfile, dir); map; map = map->map_next)
996 if (! strcmp (map->map_from, from))
1002 /* Returns true if it is safe to remove the final component of path,
1003 when it is followed by a ".." component. We use lstat to avoid
1004 symlinks if we have it. If not, we can still catch errors with
1007 remove_component_p (path)
1014 result = lstat (path, &s);
1016 result = stat (path, &s);
1019 /* There's no guarantee that errno will be unchanged, even on
1020 success. Cygwin's lstat(), for example, will often set errno to
1021 ENOSYS. In case of success, reset errno to zero. */
1025 return result == 0 && S_ISDIR (s.st_mode);
1028 /* Simplify a path name in place, deleting redundant components. This
1029 reduces OS overhead and guarantees that equivalent paths compare
1030 the same (modulo symlinks).
1033 foo/bar/../quux foo/quux
1037 //quux //quux (POSIX allows leading // as a namespace escape)
1039 Guarantees no trailing slashes. All transforms reduce the length
1040 of the string. Returns PATH. errno is 0 if no error occurred;
1041 nonzero if an error occurred when using stat () or lstat (). */
1044 _cpp_simplify_pathname (path)
1049 char *base, *orig_base;
1053 /* Don't overflow the empty path by putting a '.' in it below. */
1057 #if defined (HAVE_DOS_BASED_FILE_SYSTEM)
1058 /* Convert all backslashes to slashes. */
1059 for (from = path; *from; from++)
1060 if (*from == '\\') *from = '/';
1062 /* Skip over leading drive letter if present. */
1063 if (ISALPHA (path[0]) && path[1] == ':')
1064 from = to = &path[2];
1071 /* Remove redundant leading /s. */
1080 /* 3 or more initial /s are equivalent to 1 /. */
1081 while (*++from == '/');
1083 /* On some hosts // differs from /; Posix allows this. */
1088 base = orig_base = to;
1093 while (*from == '/')
1101 if (from[1] == '\0')
1108 else if (from[1] == '.' && (from[2] == '/' || from[2] == '\0'))
1110 /* Don't simplify if there was no previous component. */
1111 if (absolute && orig_base == to)
1116 /* Don't simplify if the previous component was "../",
1117 or if an error has already occurred with (l)stat. */
1118 if (base != to && errno == 0)
1120 /* We don't back up if it's a symlink. */
1122 if (remove_component_p (path))
1124 while (to > base && *to != '/')
1134 /* Add the component separator. */
1138 /* Copy this component until the trailing null or '/'. */
1139 while (*from != '\0' && *from != '/')
1146 /* Change the empty string to "." so that it is not treated as stdin.