Take into account the number of pushed-back bytes (ungetc).

diff --git a/ChangeLog b/ChangeLog
index 00888a8..73abc6c 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,13 @@
 2008-03-09  Bruno Haible  <bruno@clisp.org>
 
+       * lib/freadahead.h (freadahead): Document more precisely.
+       * lib/freadahead.c (freadahead): When an ungetc is in effect, return
+       the sum of both buffer sizes.
+       * tests/test-freadahead.c (main): Also test behaviour after ungetc.
+       * NEWS: Document the change.
+
+2008-03-09  Bruno Haible  <bruno@clisp.org>
+
        Extend freadptr to return also the buffer size.
        * lib/freadptr.h (freadptr): Add sizep argument.
        * lib/freadptr.c: Include freadptr.h, not freadahead.h.

diff --git a/NEWS b/NEWS
index f541b61..95ca64a 100644 (file)
--- a/NEWS
+++ b/NEWS
@@ -6,6 +6,9 @@ User visible incompatible changes
 
 Date        Modules         Changes
 
+2008-03-06  freadahead      The return value's computation has changed. It
+                            now increases by 1 after ungetc.
+
 2008-01-26  isnan-nolibm    The module name is changed from isnan-nolibm to
                             isnand-nolibm. The include file is changed from
                             "isnan.h" to "isnand.h". The function that it

diff --git a/lib/freadahead.c b/lib/freadahead.c
index daad290..a28595d 100644 (file)
--- a/lib/freadahead.c
+++ b/lib/freadahead.c
@@ -1,5 +1,5 @@
 /* Retrieve information about a FILE stream.
-   Copyright (C) 2007 Free Software Foundation, Inc.
+   Copyright (C) 2007-2008 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
@@ -25,11 +25,24 @@ freadahead (FILE *fp)
 #if defined _IO_ferror_unlocked     /* GNU libc, BeOS */
   if (fp->_IO_write_ptr > fp->_IO_write_base)
     return 0;
-  return fp->_IO_read_end - fp->_IO_read_ptr;
+  return (fp->_IO_read_end - fp->_IO_read_ptr)
+        + (fp->_flags & _IO_IN_BACKUP ? fp->_IO_save_end - fp->_IO_save_base :
+           0);
 #elif defined __sferror             /* FreeBSD, NetBSD, OpenBSD, MacOS X, Cygwin */
+# if defined __NetBSD__ || defined __OpenBSD__
+  struct __sfileext
+    {
+      struct  __sbuf _ub; /* ungetc buffer */
+      /* More fields, not relevant here.  */
+    };
+# define HASUB(fp) (((struct __sfileext *) (fp)->_ext._base)->_ub._base != NULL)
+# else
+# define HASUB(fp) ((fp)->_ub._base != NULL)
+# endif
   if ((fp->_flags & __SWR) != 0 || fp->_r < 0)
     return 0;
-  return fp->_r;
+  return fp->_r
+        + (HASUB (fp) ? fp->_ur : 0);
 #elif defined _IOERR                /* AIX, HP-UX, IRIX, OSF/1, Solaris, mingw */
 # if defined __sun && defined _LP64 /* Solaris/{SPARC,AMD64} 64-bit */
 #  define fp_ ((struct { unsigned char *_ptr; \
@@ -51,16 +64,21 @@ freadahead (FILE *fp)
 # ifdef __STDIO_BUFFERS
   if (fp->__modeflags & __FLAG_WRITING)
     return 0;
-  return fp->__bufread - fp->__bufpos;
+  return (fp->__bufread - fp->__bufpos)
+        + (fp->__modeflags & __FLAG_UNGOT ? 1 : 0);
 # else
   return 0;
 # endif
 #elif defined __QNX__               /* QNX */
   if ((fp->_Mode & 0x2000 /* _MWRITE */) != 0)
     return 0;
-  /* fp->_Buf <= fp->_Next <= fp->_Rend */
-  return fp->_Rend - fp->_Next;
+  /* fp->_Buf <= fp->_Next <= fp->_Rend,
+     and fp->_Rend may be overridden by fp->_Rsave. */
+  return ((fp->_Rsave ? fp->_Rsave : fp->_Rend) - fp->_Next)
+        + (fp->_Mode & 0x4000 /* _MBYTE */
+           ? (fp->_Back + sizeof (fp->_Back)) - fp->_Rback
+           : 0);
 #else
- #error "Please port gnulib freadahead.c to your platform! Look at the definition of fflush, fread on your system, then report this to bug-gnulib."
+ #error "Please port gnulib freadahead.c to your platform! Look at the definition of fflush, fread, ungetc on your system, then report this to bug-gnulib."
 #endif
 }

diff --git a/lib/freadahead.h b/lib/freadahead.h
index 430dcf8..96a97d1 100644 (file)
--- a/lib/freadahead.h
+++ b/lib/freadahead.h
@@ -1,5 +1,5 @@
 /* Retrieve information about a FILE stream.
-   Copyright (C) 2007 Free Software Foundation, Inc.
+   Copyright (C) 2007-2008 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
@@ -23,6 +23,8 @@ extern "C" {
 
 /* Assuming the stream STREAM is open for reading:
    Return the number of bytes waiting in the input buffer of STREAM.
+   This includes both the bytes that have been read from the underlying input
+   source and the bytes that have been pushed back through 'ungetc'.
 
    If this number is 0 and the stream is not currently writing,
    fflush (STREAM) is known to be a no-op.

diff --git a/tests/test-freadahead.c b/tests/test-freadahead.c
index d4b098a..447b188 100644 (file)
--- a/tests/test-freadahead.c
+++ b/tests/test-freadahead.c
@@ -1,5 +1,5 @@
 /* Test of freadahead() function.
-   Copyright (C) 2007 Free Software Foundation, Inc.
+   Copyright (C) 2007-2008 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
@@ -54,8 +54,29 @@ main (int argc, char **argv)
           __STDIO_BUFFERS.  */
        ASSERT (freadahead (stdin) == 0);
       else
-       /* Normal buffered stdio.  */
-       ASSERT (freadahead (stdin) != 0);
+       {
+         /* Normal buffered stdio.  */
+         size_t buffered;
+         int c, c2;
+
+         ASSERT (freadahead (stdin) != 0);
+         buffered = freadahead (stdin);
+
+         c = fgetc (stdin);
+         ASSERT (freadahead (stdin) == buffered - 1);
+         ungetc (c, stdin);
+         ASSERT (freadahead (stdin) == buffered);
+         c2 = fgetc (stdin);
+         ASSERT (c2 == c);
+         ASSERT (freadahead (stdin) == buffered - 1);
+
+         c = '@';
+         ungetc (c, stdin);
+         ASSERT (freadahead (stdin) == buffered);
+         c2 = fgetc (stdin);
+         ASSERT (c2 == c);
+         ASSERT (freadahead (stdin) == buffered - 1);
+       }
     }
 
   return 0;