freading has an undefined value after repositioning a read-write stream.

diff --git a/ChangeLog b/ChangeLog
index e538c9c8b9774b61a20ca953891dcab47748b664..f819138fd5ea13c1289a60aaf0eefa23085f27a1 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+2007-04-29  Bruno Haible  <bruno@clisp.org>
+
+       * lib/freading.h: Improve comments.
+       * lib/fwriting.h: Likewise.
+       * tests/test-freading.c (main): Don't check freading immediately after
+       repositioning. Needed for glibc.
+
 2007-04-29  Bruno Haible  <bruno@clisp.org>
 
        * lib/freading.c (freading): Trivial simplification.

diff --git a/lib/freading.h b/lib/freading.h
index 1845de1a85572497f319480e66bad92abaa60d10..9bd2eaf3abd47213a3163d5e684bfca787dea415 100644 (file)
--- a/lib/freading.h
+++ b/lib/freading.h
@@ -24,10 +24,12 @@
    writing and there is no current read operation (such as fputc).
 
    freading and fwriting will never both be true.  If STREAM supports
-   both reads and writes, then both freading and fwriting might be
-   false when the stream is first opened, after repositioning (such as
-   fseek, fsetpos, or rewind), after read encounters EOF, or after
-   fflush, depending on the underlying implementation.
+   both reads and writes, then:
+     - both freading and fwriting might be false when the stream is first
+       opened, after read encounters EOF, or after fflush,
+     - freading might be false or true and fwriting might be false
+       after repositioning (such as fseek, fsetpos, or rewind),
+   depending on the underlying implementation.
 
    STREAM must not be wide-character oriented.  */
 

diff --git a/lib/fwriting.h b/lib/fwriting.h
index b354186c85877d1a1a801e34214af80253a4dc0c..cba2b132b433cf287bd362bb28fcf30099a985eb 100644 (file)
--- a/lib/fwriting.h
+++ b/lib/fwriting.h
@@ -25,10 +25,12 @@
    as fputc).
 
    freading and fwriting will never both be true.  If STREAM supports
-   both reads and writes, then both freading and fwriting might be
-   false when the stream is first opened, after repositioning (such as
-   fseek, fsetpos, or rewind), after read encounters EOF, or after
-   fflush, depending on the underlying implementation.
+   both reads and writes, then:
+     - both freading and fwriting might be false when the stream is first
+       opened, after read encounters EOF, or after fflush,
+     - freading might be false or true and fwriting might be false
+       after repositioning (such as fseek, fsetpos, or rewind),
+   depending on the underlying implementation.
 
    STREAM must not be wide-character oriented.  */
 

diff --git a/tests/test-freading.c b/tests/test-freading.c
index 3d69c404eaad456dee448348b344dc31e5691425..b2f6fc7b07c4be60510430efe8cd97fab10ef8c8 100644 (file)
--- a/tests/test-freading.c
+++ b/tests/test-freading.c
@@ -97,7 +97,9 @@ main ()
   ASSERT (!freading (fp));
   if (fseek (fp, 0, SEEK_END))
     goto skip;
-  ASSERT (!freading (fp));
+  /* freading (fp) is undefined here, because on some implementations (e.g.
+     glibc) fseek causes a buffer to be read.
+     fwriting (fp) is undefined as well.  */
   if (fclose (fp))
     goto skip;
 
@@ -135,7 +137,9 @@ main ()
   ASSERT (!freading (fp));
   if (fseek (fp, 0, SEEK_END))
     goto skip;
-  ASSERT (!freading (fp));
+  /* freading (fp) is undefined here, because on some implementations (e.g.
+     glibc) fseek causes a buffer to be read.
+     fwriting (fp) is undefined as well.  */
   if (fclose (fp))
     goto skip;
 

diff --git a/tests/test-fwriting.c b/tests/test-fwriting.c
index 690a35f3060d6b08ee6d32d01e67185b80879d5e..0f97df5ccf59616ce2d8aff0fc0e0191f1bf2532 100644 (file)
--- a/tests/test-fwriting.c
+++ b/tests/test-fwriting.c
@@ -97,7 +97,9 @@ main ()
   ASSERT (fwriting (fp));
   if (fseek (fp, 0, SEEK_END))
     goto skip;
-  /* fwriting (fp) is undefined here, but freading (fp) is false.  */
+  /* freading (fp) is undefined here, because on some implementations (e.g.
+     glibc) fseek causes a buffer to be read.
+     fwriting (fp) is undefined as well.  */
   if (fclose (fp))
     goto skip;
 
@@ -135,7 +137,9 @@ main ()
   ASSERT (fwriting (fp));
   if (fseek (fp, 0, SEEK_END))
     goto skip;
-  /* fwriting (fp) is undefined here, but freading (fp) is false.  */
+  /* freading (fp) is undefined here, because on some implementations (e.g.
+     glibc) fseek causes a buffer to be read.
+     fwriting (fp) is undefined as well.  */
   if (fclose (fp))
     goto skip;