getcwd: on Solaris, work better if ancestors are inaccessible

* lib/getcwd.c (__getcwd): If getcwd returns EINVAL for zero
buffer and size, try again with a large buffer.  This works better
on Solaris, since its getcwd succeeds even if the path to the root
is inaccessible, and this is helpful in common cases such as .zfs
hidden directories.  Problem reported by J Chapman Flack in
http://lists.gnu.org/archive/html/bug-tar/2010-06/msg00000.html
Use system getcwd if it's declared, not merely if it's partly
working; use the partly-working test only to avoid needless effort
if the system getcwd fails.
* m4/getcwd-path-max.m4 (gl_FUNC_GETCWD_PATH_MAX): Omit
comment that was already obsolete and is now even more obsolete.
* modules/getcwd (Depends-on): Depend on strdup, since __getcwd
now might call strdup.

diff --git a/ChangeLog b/ChangeLog
index b8c73c56e18fe34cabc43e42644f78cf21c063d5..c1adeac174f31044f34f6af7753bc4bf6a0c06e6 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,20 @@
+2010-07-14  Paul R. Eggert  <eggert@cs.ucla.edu>
+
+       getcwd: on Solaris, work better if ancestors are inaccessible
+       * lib/getcwd.c (__getcwd): If getcwd returns EINVAL for zero
+       buffer and size, try again with a large buffer.  This works better
+       on Solaris, since its getcwd succeeds even if the path to the root
+       is inaccessible, and this is helpful in common cases such as .zfs
+       hidden directories.  Problem reported by J Chapman Flack in
+       http://lists.gnu.org/archive/html/bug-tar/2010-06/msg00000.html
+       Use system getcwd if it's declared, not merely if it's partly
+       working; use the partly-working test only to avoid needless effort
+       if the system getcwd fails.
+       * m4/getcwd-path-max.m4 (gl_FUNC_GETCWD_PATH_MAX): Omit
+       comment that was already obsolete and is now even more obsolete.
+       * modules/getcwd (Depends-on): Depend on strdup, since __getcwd
+       now might call strdup.
+
 2010-07-13  Paul R. Eggert  <eggert@cs.ucla.edu>
 
        pthread: Add enough so that coreutils/src/sort.c compiles.

diff --git a/lib/getcwd.c b/lib/getcwd.c
index 1ba705c38c87f42e3fdc47ed877b3ed48ae58142..7d47072101e7fdc4d339c8cd77a92b115c89afe6 100644 (file)
--- a/lib/getcwd.c
+++ b/lib/getcwd.c
@@ -136,13 +136,11 @@ __getcwd (char *buf, size_t size)
   size_t allocated = size;
   size_t used;
 
-#if HAVE_PARTLY_WORKING_GETCWD
-  /* The system getcwd works, except it sometimes fails when it
-     shouldn't, setting errno to ERANGE, ENAMETOOLONG, or ENOENT.  If
-     AT_FDCWD is not defined, the algorithm below is O(N**2) and this
-     is much slower than the system getcwd (at least on GNU/Linux).
-     So trust the system getcwd's results unless they look
-     suspicious.
+#if HAVE_RAW_DECL_GETCWD
+  /* If AT_FDCWD is not defined, the algorithm below is O(N**2) and
+     this is much slower than the system getcwd (at least on
+     GNU/Linux).  So trust the system getcwd's results unless they
+     look suspicious.
 
      Use the system getcwd even if we have openat support, since the
      system getcwd works even when a parent is unreadable, while the
@@ -150,8 +148,27 @@ __getcwd (char *buf, size_t size)
 
 # undef getcwd
   dir = getcwd (buf, size);
-  if (dir || (errno != ERANGE && errno != ENAMETOOLONG && errno != ENOENT))
+  if (dir)
     return dir;
+
+  /* Solaris getcwd (NULL, 0) fails with errno == EINVAL, but it has
+     internal magic that lets it work even if an ancestor directory is
+     inaccessible, which is better in many cases.  So in this case try
+     again with a buffer that's almost always big enough.  */
+  if (errno == EINVAL && buf == NULL && size == 0)
+    {
+      char big_buffer[BIG_FILE_NAME_LENGTH + 1];
+      dir = getcwd (big_buffer, sizeof big_buffer);
+      if (dir)
+        return strdup (dir);
+    }
+
+# if HAVE_PARTLY_WORKING_GETCWD
+  /* The system getcwd works, except it sometimes fails when it
+     shouldn't, setting errno to ERANGE, ENAMETOOLONG, or ENOENT.    */
+  if (errno != ERANGE && errno != ENAMETOOLONG && errno != ENOENT)
+    return NULL;
+# endif
 #endif
 
   if (size == 0)

diff --git a/m4/getcwd-path-max.m4 b/m4/getcwd-path-max.m4
index ecf6192842e11b38144840c6869d8c02b2c21657..04ff1419b6032fa8aa329994c23cda515f8f0da3 100644 (file)
--- a/m4/getcwd-path-max.m4
+++ b/m4/getcwd-path-max.m4
@@ -183,8 +183,6 @@ main ()
   no,*)
     AC_DEFINE([HAVE_PARTLY_WORKING_GETCWD], [1],
       [Define to 1 if getcwd works, except it sometimes fails when it shouldn't,
-       setting errno to ERANGE, ENAMETOOLONG, or ENOENT.  If __GETCWD_PREFIX
-       is not defined, it doesn't matter whether HAVE_PARTLY_WORKING_GETCWD
-       is defined.]);;
+       setting errno to ERANGE, ENAMETOOLONG, or ENOENT.]);;
   esac
 ])

diff --git a/modules/getcwd b/modules/getcwd
index cec9e2a5117f93190234d370efb93d832d02b494..c1544f5e5f149db26dbf5dbf6699e5355e47894e 100644 (file)
--- a/modules/getcwd
+++ b/modules/getcwd
@@ -17,6 +17,7 @@ openat
 stdbool
 unistd
 malloc-posix
+strdup-posix
 
 configure.ac:
 gl_FUNC_GETCWD