Re: PATH_MAX

[Jim Meyering]

Neal H Walfield <address@hidden> wrote:
> This bug report was verified against v 2.0.11-11 as found in the Debian
> unstable archive and the version marked as 2.0 on ftp.gnu.org.  I did
> not see a cvs module on subversions.
>
> Shell utils makes use of the macro PATH_MAX.  On the Hurd, this is
> undefined.  Happily, shell utils handles this situation by using
> pathconf, however, it does so incorrectly: pathconf returns -1 on the
> Hurd.  By definition, this means that there is no system imposed limit
> but shell utils chooses to use 1024 in this case.  This is clearly
> a hack and is wrong.  Dynamic allocation checking for ENAMETOOLONG,
> etc., should instead be performed.

Thanks for the report.
I've begun fixing that.
Here's the first installment (untested):

        * src/pathchk.c (PATH_MAX_FOR): Use pathconf via wrapper.
        (NAME_MAX_FOR): Likewise.
        Guard the above pathconf-using definitions with `#if HAVE_PATHCONF'
        rather than with `#ifdef _POSIX_VERSION'.
        (pathconf_wrapper): New function.
        (validate_path): Declare length variables to be `long', not `int'.
        Adjust corresponding printf-style specs to use %ld.

Would you please give it a try?

Jim

Index: pathchk.c
===================================================================
RCS file: /fetish/shellutils/src/pathchk.c,v
retrieving revision 1.52
diff -u -p -r1.52 pathchk.c
--- pathchk.c   2000/05/07 14:55:48     1.52
+++ pathchk.c   2001/08/12 18:42:50
@@ -1,5 +1,5 @@
 /* pathchk -- check whether pathnames are valid or portable
-   Copyright (C) 1991-2000 Free Software Foundation, Inc.
+   Copyright (C) 1991-2001 Free Software Foundation, Inc.
 
    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
@@ -43,6 +43,11 @@
 #include <getopt.h>
 #include <sys/types.h>
 
+#include <errno.h>
+#ifndef errno
+extern int errno;
+#endif
+
 #include "system.h"
 #include "error.h"
 #include "long-options.h"
@@ -53,15 +58,15 @@
 
 #define AUTHORS "David MacKenzie and Jim Meyering"
 
-#ifdef _POSIX_VERSION
+#if HAVE_PATHCONF
 # ifndef PATH_MAX
-#  define PATH_MAX_FOR(p) pathconf ((p), _PC_PATH_MAX)
+#  define PATH_MAX_FOR(p) pathconf_wrapper ((p), _PC_PATH_MAX)
 # endif /* not PATH_MAX */
 # ifndef NAME_MAX
-#  define NAME_MAX_FOR(p) pathconf ((p), _PC_NAME_MAX);
+#  define NAME_MAX_FOR(p) pathconf_wrapper ((p), _PC_NAME_MAX);
 # endif /* not NAME_MAX */
 
-#else /* not _POSIX_VERSION */
+#else
 
 # include <sys/param.h>
 # ifndef PATH_MAX
@@ -80,7 +85,7 @@
 #  endif /* not MAXNAMLEN */
 # endif /* not NAME_MAX */
 
-#endif /* not _POSIX_VERSION */
+#endif
 
 #ifndef _POSIX_PATH_MAX
 # define _POSIX_PATH_MAX 255
@@ -107,6 +112,23 @@ static struct option const longopts[] =
   {NULL, 0, NULL, 0}
 };
 
+/* Distinguish between the cases when pathconf fails and when it reports there
+   is no limit (the latter is the case for PATH_MAX on the Hurd).  When there
+   is no limit, return LONG_MAX.  Otherwise, return pathconf's return value.  
*/
+
+static long int
+pathconf_wrapper (const char *filename, int param)
+{
+  long int ret;
+
+  errno = 0;
+  ret = pathconf (filename, param);
+  if (ret < 0 && errno == 0)
+    return LONG_MAX;
+
+  return ret;
+}
+
 void
 usage (int status)
 {
@@ -263,7 +285,7 @@ dir_ok (const char *path)
 static int
 validate_path (char *path, int portability)
 {
-  int path_max;
+  long int path_max;
   int last_elem;               /* Nonzero if checking last element of path. */
   int exists IF_LINT (= 0);    /* 2 if the path element exists.  */
   char *slash;
@@ -282,8 +304,8 @@ validate_path (char *path, int portabili
   last_elem = 0;
   while (1)
     {
-      int name_max;
-      int length;              /* Length of partial path being checked. */
+      long int name_max;
+      long int length;         /* Length of partial path being checked. */
       char *start;             /* Start of path element being checked. */
 
       /* Find the end of this element of the path.
@@ -324,7 +346,7 @@ validate_path (char *path, int portabili
        name_max = _POSIX_NAME_MAX;
       if (length > name_max)
        {
-         error (0, 0, _("name `%s' has length %d; exceeds limit of %d"),
+         error (0, 0, _("name `%s' has length %ld; exceeds limit of %ld"),
                 start, length, name_max);
          free (parent);
          return 1;
@@ -350,7 +372,7 @@ validate_path (char *path, int portabili
   free (parent);
   if (strlen (path) > (size_t) path_max)
     {
-      error (0, 0, _("path `%s' has length %d; exceeds limit of %d"),
+      error (0, 0, _("path `%s' has length %d; exceeds limit of %ld"),
             path, strlen (path), path_max);
       return 1;
     }