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-rw-r--r--stdlib/Makefile2
-rw-r--r--stdlib/canonicalize.c196
-rw-r--r--stdlib/stdlib.h18
3 files changed, 215 insertions, 1 deletions
diff --git a/stdlib/Makefile b/stdlib/Makefile
index ddcc385ab9..d30a0f2a06 100644
--- a/stdlib/Makefile
+++ b/stdlib/Makefile
@@ -40,7 +40,7 @@ routines	:=							      \
 	drand48-iter							      \
 	strtol strtoul strtoq strtouq					      \
 	strtof strtod strtold						      \
-	system realpath							      \
+	system canonicalize						      \
 	a64l l64a							      \
 	rpmatch strfmon
 
diff --git a/stdlib/canonicalize.c b/stdlib/canonicalize.c
new file mode 100644
index 0000000000..55ac1bcf1d
--- /dev/null
+++ b/stdlib/canonicalize.c
@@ -0,0 +1,196 @@
+/* Return the canonical absolute name of a given file.
+Copyright (C) 1996 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 Library General Public License as
+published by the Free Software Foundation; either version 2 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
+Library General Public License for more details.
+
+You should have received a copy of the GNU Library General Public
+License along with the GNU C Library; see the file COPYING.LIB.  If
+not, write to the Free Software Foundation, Inc., 675 Mass Ave,
+Cambridge, MA 02139, USA.  */
+
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <limits.h>
+#include <sys/stat.h>
+#include <errno.h>
+
+/* Return the canonical absolute name of file NAME.  The last file name
+   component need not exist, and may be a symlink to a nonexistent file.
+   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.  */
+
+static char *
+canonicalize (const char *name, char *resolved)
+{
+  struct stat st;
+  const char *p;
+  long int path_max;
+  char *result, *dir, *end;
+  size_t namelen;
+
+  if (! resolved)
+    path_max = 0;
+  else
+    {
+#ifdef PATH_MAX
+      path_max = PATH_MAX;
+#else
+      path_max = sysconf (_SC_PATH_MAX);
+      if (path_max <= 0)
+	path_max = 1024;
+#endif
+    }
+
+  p = strrchr (name, '/');
+  if (!p)
+    {
+      dir = (char *) ".";
+      p = name;
+    }
+  else
+    {
+      if (p++ == name)
+	dir = (char *) "/";
+      else
+	{
+	  dir = __alloca (p - name);
+	  memcpy (dir, name, p - name - 1);
+	  dir[p - name] = '\0';
+	}
+    }
+
+  result = __canonicalize_directory_name_internal (dir, resolved, path_max);
+  if (!result)
+    return NULL;
+
+  /* Reconstruct the file name in the canonicalized directory.  */
+  namelen = strlen (name);
+  end = strchr (result, '\0');
+  if (resolved)
+    {
+      /* Make sure the name is not too long.  */
+      if (end - result + namelen > path_max)
+	{
+	  errno = ENAMETOOLONG;
+	  return NULL;
+	}
+    }
+  else
+    {
+      /* The name is dynamically allocated.  Extend it.  */
+      char *new = realloc (result, end - result + namelen + 1);
+      if (! new)
+	{
+	  free (result);
+	  return NULL;
+	}
+      end = new + (end - result);
+      result = new;
+    }
+  memcpy (end, name, namelen + 1);
+
+  while (__lstat (result, &st) == 0 && S_ISLNK (st.st_mode))
+    {
+      /* The file is a symlink.  Read its contents.  */
+      ssize_t n;
+    read_link_contents:
+      n = readlink (result, end,
+		    resolved ? result + path_max - end : namelen + 1);
+      if (n < 0)
+	/* Error reading the link contents.  */
+	return NULL;
+
+      if (end[0] == '/')
+	{
+	  /* Absolute symlink.  */
+	  if (resolved ? (end + n < result + path_max) : (n < namelen + 1))
+	    {
+	      /* It fit in our buffer, so we have the whole thing.  */
+	      memcpy (result, end, n);
+	      result[n] = '\0';
+	    }
+	  else if (resolved)
+	    {
+	      /* It didn't fit in the remainder of the buffer.  Either it
+		 fits in the entire buffer, or it doesn't.  Copy back the
+		 unresolved name onto the canonical directory and try once
+		 more.  */
+	      memcpy (end, name, namelen + 1);
+	      n = readlink (result, result, path_max);
+	      if (n < 0)
+		return NULL;
+	      if (n == path_max)
+		{
+		  errno = ENAMETOOLONG;
+		  return NULL;
+		}
+	      result[n] = '\0';
+	    }
+	  else
+	    /* Try again with a bigger buffer.  */
+	    goto extend_buffer;
+
+	  /* Check the resolved name for being a symlink too.  */
+	  continue;
+	}
+
+      if (resolved)
+	{
+	  if (end + n == result + path_max)
+	    {
+	      /* The link contents we read fill the buffer completely.
+		 There may be even more to read, and there is certainly no
+		 space for the null terminator.  */
+	      errno = ENAMETOOLONG;
+	      return NULL;
+	    }
+	}
+      else if (n == namelen + 1)
+      extend_buffer:
+	{
+	  /* The name buffer is dynamically allocated.  Extend it.  */
+	  char *new;
+
+	  /* Copy back the unresolved name onto the canonical directory.  */
+	  memcpy (end, name, namelen + 1);
+
+	  /* Make more space for readlink.  */
+	  namelen *= 2;
+	  new = realloc (result, end - result + namelen + 1);
+	  if (! new)
+	    {
+	      free (result);
+	      return NULL;
+	    }
+	  end = new + (end - result);
+	  result = new;
+
+	  goto read_link_contents;
+	}
+
+      /* Terminate the string; readlink does not.  */
+      end[n] = '\0';
+    }
+
+  return result;
+}
+
+weak_alias (canonicalize, realpath)
+
+char *
+canonicalize_file_name (const char *name)
+{
+  return canonicalize (name, NULL);
+}
diff --git a/stdlib/stdlib.h b/stdlib/stdlib.h
index 2fde1c806f..1853c5babb 100644
--- a/stdlib/stdlib.h
+++ b/stdlib/stdlib.h
@@ -364,6 +364,24 @@ extern void unsetenv __P ((__const char *__name));
 extern int system __P ((__const char *__command));
 
 
+#ifdef	__USE_GNU
+/* Return a malloc'd string containing the canonical absolute name of the
+   named file.  The last file name component need not exist, and may be a
+   symlink to a nonexistent file.  */
+extern char *canonicalize_file_name __P ((__const char *__name));
+#endif
+
+#ifdef	__USE_BSD
+/* Return the canonical absolute name of file NAME.  The last file name
+   component need not exist, and may be a symlink to a nonexistent file.
+   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.  */
+extern char *realpath __P ((__const char *__name, char *__resolved));
+#endif
+
+
 /* Shorthand for type of comparison functions.  */
 #ifndef __COMPAR_FN_T
 #define __COMPAR_FN_T