diff --git a/stdlib/canonicalize.c b/stdlib/canonicalize.c
index 3fcb399a5d..2770f4ae44 100644
--- a/stdlib/canonicalize.c
+++ b/stdlib/canonicalize.c
@@ -16,8 +16,9 @@
    License along with the GNU C Library; if not, see
    <https://www.gnu.org/licenses/>.  */
 
-#include <assert.h>
 #include <stdlib.h>
+
+#include <alloca.h>
 #include <string.h>
 #include <unistd.h>
 #include <limits.h>
@@ -29,10 +30,10 @@
 #include <shlib-compat.h>
 
 /* Return the canonical absolute name of file NAME.  A canonical name
-   does not contain any `.', `..' components nor any repeated path
+   does not contain any ".", ".." components nor any repeated path
    separators ('/') or symlinks.  All path 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'
+   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 path of the first component
@@ -50,9 +51,9 @@ __realpath (const char *name, char *resolved)
   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.  */
+         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;
     }
@@ -60,7 +61,7 @@ __realpath (const char *name, char *resolved)
   if (name[0] == '\0')
     {
       /* As per Single Unix Specification V2 we must return an error if
-	 the name argument points to an empty string.  */
+         the name argument points to an empty string.  */
       __set_errno (ENOENT);
       return NULL;
     }
@@ -70,152 +71,169 @@ __realpath (const char *name, char *resolved)
 #else
   path_max = __pathconf (name, _PC_PATH_MAX);
   if (path_max <= 0)
-    path_max = 1024;
+    path_max = 8192;
 #endif
 
   if (resolved == NULL)
     {
       rpath = malloc (path_max);
       if (rpath == NULL)
-	return NULL;
+        return NULL;
     }
   else
     rpath = resolved;
   rpath_limit = rpath + path_max;
 
+
   if (name[0] != '/')
     {
       if (!__getcwd (rpath, path_max))
-	{
-	  rpath[0] = '\0';
-	  goto error;
-	}
-      dest = __rawmemchr (rpath, '\0');
+        {
+          rpath[0] = '\0';
+          goto error;
+        }
+      dest = strchr (rpath, '\0');
     }
   else
     {
-      rpath[0] = '/';
-      dest = rpath + 1;
+      dest = rpath;
+      *dest++ = '/';
     }
+  start = name;
 
-  for (start = end = name; *start; start = end)
+  for (end = start; *start; start = end)
     {
+#ifdef _LIBC
       struct stat64 st;
-      int n;
+#else
+      struct stat st;
+#endif
 
       /* Skip sequence of multiple path-separators.  */
       while (*start == '/')
-	++start;
+        ++start;
 
       /* Find end of path component.  */
       for (end = start; *end && *end != '/'; ++end)
-	/* Nothing.  */;
+        /* Nothing.  */;
 
       if (end - start == 0)
-	break;
+        break;
       else if (end - start == 1 && start[0] == '.')
-	/* nothing */;
+        /* nothing */;
       else if (end - start == 2 && start[0] == '.' && start[1] == '.')
-	{
-	  /* Back up to previous component, ignore if at root already.  */
-	  if (dest > rpath + 1)
-	    while ((--dest)[-1] != '/');
-	}
+        {
+          /* Back up to previous component, ignore if at root already.  */
+          if (dest > rpath + 1)
+            for (--dest; dest > rpath && dest[-1] != '/'; --dest)
+              continue;
+        }
       else
-	{
-	  size_t new_size;
-
-	  if (dest[-1] != '/')
-	    *dest++ = '/';
-
-	  if (dest + (end - start) >= rpath_limit)
-	    {
-	      ptrdiff_t dest_offset = dest - rpath;
-	      char *new_rpath;
-
-	      if (resolved)
-		{
-		  __set_errno (ENAMETOOLONG);
-		  if (dest > rpath + 1)
-		    dest--;
-		  *dest = '\0';
-		  goto error;
-		}
-	      new_size = rpath_limit - rpath;
-	      if (end - start + 1 > path_max)
-		new_size += end - start + 1;
-	      else
-		new_size += path_max;
-	      new_rpath = (char *) realloc (rpath, new_size);
-	      if (new_rpath == NULL)
-		goto error;
-	      rpath = new_rpath;
-	      rpath_limit = rpath + new_size;
-
-	      dest = rpath + dest_offset;
-	    }
-
-	  dest = __mempcpy (dest, start, end - start);
-	  *dest = '\0';
-
-	  if (__lstat64 (rpath, &st) < 0)
-	    goto error;
-
-	  if (S_ISLNK (st.st_mode))
-	    {
-	      char *buf = __alloca (path_max);
-	      size_t len;
-
-	      if (++num_links > __eloop_threshold ())
-		{
-		  __set_errno (ELOOP);
-		  goto error;
-		}
-
-	      n = __readlink (rpath, buf, path_max - 1);
-	      if (n < 0)
-		goto error;
-	      buf[n] = '\0';
-
-	      if (!extra_buf)
-		extra_buf = __alloca (path_max);
-
-	      len = strlen (end);
-	      if (path_max - n <= len)
-		{
-		  __set_errno (ENAMETOOLONG);
-		  goto error;
-		}
-
-	      /* Careful here, end may be a pointer into extra_buf... */
-	      memmove (&extra_buf[n], end, len + 1);
-	      name = end = memcpy (extra_buf, buf, n);
-
-	      if (buf[0] == '/')
-		dest = rpath + 1;	/* It's an absolute symlink */
-	      else
-		/* Back up to previous component, ignore if at root already: */
-		if (dest > rpath + 1)
-		  while ((--dest)[-1] != '/');
-	    }
-	  else if (!S_ISDIR (st.st_mode) && *end != '\0')
-	    {
-	      __set_errno (ENOTDIR);
-	      goto error;
-	    }
-	}
+        {
+          size_t new_size;
+
+          if (dest[-1] != '/')
+            *dest++ = '/';
+
+          if (dest + (end - start) >= rpath_limit)
+            {
+              ptrdiff_t dest_offset = dest - rpath;
+              char *new_rpath;
+
+              if (resolved)
+                {
+                  __set_errno (ENAMETOOLONG);
+                  if (dest > rpath + 1)
+                    dest--;
+                  *dest = '\0';
+                  goto error;
+                }
+              new_size = rpath_limit - rpath;
+              if (end - start + 1 > path_max)
+                new_size += end - start + 1;
+              else
+                new_size += path_max;
+              new_rpath = (char *) realloc (rpath, new_size);
+              if (new_rpath == NULL)
+                goto error;
+              rpath = new_rpath;
+              rpath_limit = rpath + new_size;
+
+              dest = rpath + dest_offset;
+            }
+
+          dest = __mempcpy (dest, start, end - start);
+          *dest = '\0';
+
+          if (__lstat64 (rpath, &st) < 0)
+            goto error;
+
+          if (S_ISLNK (st.st_mode))
+            {
+              char *buf = __alloca (path_max);
+              size_t len;
+              ssize_t n;
+
+              if (++num_links > __eloop_threshold ())
+                {
+                  __set_errno (ELOOP);
+                  goto error;
+                }
+
+              n = __readlink (rpath, buf, path_max - 1);
+              if (n < 0)
+                goto error;
+              buf[n] = '\0';
+
+              if (!extra_buf)
+                extra_buf = __alloca (path_max);
+
+              len = strlen (end);
+              /* Check that n + len + 1 doesn't overflow and is <= path_max. */
+              if (n >= SIZE_MAX - len || n + len >= path_max)
+                {
+                  __set_errno (ENAMETOOLONG);
+                  goto error;
+                }
+
+              /* Careful here, end may be a pointer into extra_buf... */
+              memmove (&extra_buf[n], end, len + 1);
+              name = end = memcpy (extra_buf, buf, n);
+
+              if (buf[0] == '/')
+                {
+                  dest = rpath;
+                  *dest++ = '/'; /* It's an absolute symlink */
+                }
+              else
+                {
+                  /* Back up to previous component, ignore if at root
+                     already: */
+                  if (dest > rpath + 1)
+                    for (--dest; dest > rpath && dest[-1] != '/'; --dest)
+                      continue;
+                }
+            }
+          else if (!S_ISDIR (st.st_mode) && *end != '\0')
+            {
+              __set_errno (ENOTDIR);
+              goto error;
+            }
+        }
     }
   if (dest > rpath + 1 && dest[-1] == '/')
     --dest;
   *dest = '\0';
 
-  assert (resolved == NULL || resolved == rpath);
   return rpath;
 
 error:
-  assert (resolved == NULL || resolved == rpath);
-  if (resolved == NULL)
-    free (rpath);
+  {
+    int saved_errno = errno;
+    if (resolved == NULL)
+      free (rpath);
+    __set_errno (saved_errno);
+  }
   return NULL;
 }
 libc_hidden_def (__realpath)
