stdioext: Add support for musl libc.

* m4/fbufmode.m4 (gl_FUNC_FBUFMODE): Test whether __fbufsize exists.
* lib/fbufmode.c (fbufmode): Add conditional code for musl.

* m4/fseterr.m4: New file.
* lib/fseterr.h (fseterr): Define as an alias of __fseterr if that
function exists.
* modules/fseterr (Files): Add m4/fseterr.m4.
(configure.ac): Invoke gl_FUNC_FSETERR. Compile fseterr.c if
__fseterr does not exist.
(Makefile.am): Remove fseterr.c from lib_SOURCES.

* lib/freadable.h: Update comment.

* lib/fwritable.h: Update comment.

* lib/freading.h: Update comment.

* lib/fwriting.h: Update comment.

* m4/freadahead.m4: New file.
* lib/freadahead.h (freadahead): Define as an alias of __freadahead if
that function exists.
* modules/freadahead (Files): Add m4/freadahead.m4.
(configure.ac): Invoke gl_FUNC_FREADAHEAD. Compile freadahead.c if
__freadahead does not exist.
(Makefile.am): Remove freadahead.c from lib_SOURCES.

* m4/freadptr.m4: New file.
* lib/freadptr.h (freadptr): Define as an alias of __freadptr if that
function exists.
* modules/freadptr (Files): Add m4/freadptr.m4.
(configure.ac): Invoke gl_FUNC_FREADPTR. Compile freadptr.c if
__freadptr does not exist.
(Makefile.am): Remove freadptr.c from lib_SOURCES.

* m4/freadseek.m4: New file.
* lib/freadseek.c (freadptrinc): Use __freadptrinc if that function
exists.
* modules/freadseek (Files): Add m4/freadseek.m4.
(configure.ac): Invoke gl_FUNC_FREADSEEK.

* lib/fpurge.c (fpurge): Update comment.

Reported by and with help from Rich Felker <dalias@aerifal.cx>.

10 files changed, 55 insertions, 23 deletions

diff --git a/lib/fbufmode.c b/lib/fbufmode.c
index b48cdbb387..b7a79e2c31 100644
--- a/lib/fbufmode.c
+++ b/lib/fbufmode.c
@@ -79,6 +79,10 @@ fbufmode (FILE *fp)
   if (fp->__linebuf)
     return _IOLBF;
   return (fp->__bufsize > 0 ? _IOFBF : _IONBF);
+#elif HAVE___FLBF && HAVE___FBUFSIZE /* musl libc */
+  if (__flbf (fp))
+    return _IOLBF;
+  return (__fbufsize (fp) > 0 ? _IOFBF : _IONBF);
 #elif defined EPLAN9                /* Plan9 */
   if (fp->flags & 2 /* LINEBUF */)
     return _IOLBF;
diff --git a/lib/fpurge.c b/lib/fpurge.c
index 24c28d843c..a4bc667125 100644
--- a/lib/fpurge.c
+++ b/lib/fpurge.c
@@ -29,7 +29,7 @@
 int
 fpurge (FILE *fp)
 {
-#if HAVE___FPURGE                   /* glibc >= 2.2, Haiku, Solaris >= 7 */
+#if HAVE___FPURGE                   /* glibc >= 2.2, Haiku, Solaris >= 7, musl libc */
 
   __fpurge (fp);
   /* The __fpurge function does not have a return value.  */
diff --git a/lib/freadable.h b/lib/freadable.h
index 9a6c454f56..84917b96ab 100644
--- a/lib/freadable.h
+++ b/lib/freadable.h
@@ -22,7 +22,7 @@
    STREAM must not be wide-character oriented.
    The result doesn't change until the stream is closed or re-opened.  */
 
-#if HAVE___FREADABLE /* glibc >= 2.2, Solaris >= 7 */
+#if HAVE___FREADABLE /* glibc >= 2.2, Solaris >= 7, musl libc */
 
 # include <stdio_ext.h>
 # define freadable(stream) (__freadable (stream) != 0)
diff --git a/lib/freadahead.h b/lib/freadahead.h
index d87460243d..49eb00df69 100644
--- a/lib/freadahead.h
+++ b/lib/freadahead.h
@@ -17,10 +17,6 @@
 #include <stddef.h>
 #include <stdio.h>
 
-#ifdef __cplusplus
-extern "C" {
-#endif
-
 /* 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
@@ -31,8 +27,21 @@ extern "C" {
 
    STREAM must not be wide-character oriented.  */
 
+#if HAVE___FREADAHEAD /* musl libc */
+
+# include <stdio_ext.h>
+# define freadahead(stream) __freadahead (stream)
+
+#else
+
+# ifdef __cplusplus
+extern "C" {
+# endif
+
 extern size_t freadahead (FILE *stream) _GL_ATTRIBUTE_PURE;
 
-#ifdef __cplusplus
+# ifdef __cplusplus
 }
+# endif
+
 #endif
diff --git a/lib/freading.h b/lib/freading.h
index 9668d20232..86316a5be8 100644
--- a/lib/freading.h
+++ b/lib/freading.h
@@ -33,7 +33,7 @@
    STREAM must not be wide-character oriented.  */
 
 #if HAVE___FREADING && (!defined __GLIBC__ || defined __UCLIBC__ || __GLIBC__ > 2 || (__GLIBC__ == 2 && __GLIBC_MINOR__ >= 7))
-/* Solaris >= 7, not glibc >= 2.2, but glibc >= 2.7  */
+/* Solaris >= 7, not glibc >= 2.2, but glibc >= 2.7, or musl libc  */
 
 # include <stdio_ext.h>
 # define freading(stream) (__freading (stream) != 0)
diff --git a/lib/freadptr.h b/lib/freadptr.h
index 464bedb731..c7d0acd237 100644
--- a/lib/freadptr.h
+++ b/lib/freadptr.h
@@ -17,10 +17,6 @@
 #include <stddef.h>
 #include <stdio.h>
 
-#ifdef __cplusplus
-extern "C" {
-#endif
-
 /* Assuming the stream STREAM is open for reading:
    Return a pointer to the input buffer of STREAM, or NULL.
    If the returned pointer is non-NULL, *SIZEP is set to the (positive) size
@@ -32,8 +28,21 @@ extern "C" {
 
    STREAM must not be wide-character oriented.  */
 
+#if HAVE___FREADPTR /* musl libc */
+
+# include <stdio_ext.h>
+# define freadptr(stream,sizep) __freadptr (stream, sizep)
+
+#else
+
+# ifdef __cplusplus
+extern "C" {
+# endif
+
 extern const char * freadptr (FILE *stream, size_t *sizep);
 
-#ifdef __cplusplus
+# ifdef __cplusplus
 }
+# endif
+
 #endif
diff --git a/lib/freadseek.c b/lib/freadseek.c
index 4145173e9e..92923b923a 100644
--- a/lib/freadseek.c
+++ b/lib/freadseek.c
@@ -34,7 +34,9 @@ static inline void
 freadptrinc (FILE *fp, size_t increment)
 {
   /* Keep this code in sync with freadptr!  */
-#if defined _IO_ftrylockfile || __GNU_LIBRARY__ == 1 /* GNU libc, BeOS, Haiku, Linux libc5 */
+#if HAVE___FREADPTRINC              /* musl libc */
+  __freadptrinc (fp, increment);
+#elif defined _IO_ftrylockfile || __GNU_LIBRARY__ == 1 /* GNU libc, BeOS, Haiku, Linux libc5 */
   fp->_IO_read_ptr += increment;
 #elif defined __sferror || defined __DragonFly__ /* FreeBSD, NetBSD, OpenBSD, DragonFly, MacOS X, Cygwin */
   fp_->_p += increment;
diff --git a/lib/fseterr.h b/lib/fseterr.h
index b3930c5a88..16a1afeeae 100644
--- a/lib/fseterr.h
+++ b/lib/fseterr.h
@@ -19,19 +19,27 @@
 
 #include <stdio.h>
 
-#ifdef __cplusplus
-extern "C" {
-#endif
-
-
 /* Set the error indicator of the stream FP.
    The "error indicator" is set when an I/O operation on the stream fails, and
    is cleared (together with the "end-of-file" indicator) by clearerr (FP).  */
-extern void fseterr (FILE *fp);
 
+#if HAVE___FSETERR /* musl libc */
+
+# include <stdio_ext.h>
+# define fseterr(fp) __fseterr (fp)
 
-#ifdef __cplusplus
+#else
+
+# ifdef __cplusplus
+extern "C" {
+# endif
+
+extern void fseterr (FILE *fp);
+
+# ifdef __cplusplus
 }
+# endif
+
 #endif
 
 #endif /* _FSETERR_H */
diff --git a/lib/fwritable.h b/lib/fwritable.h
index 9c95dbe2ca..f5875f789c 100644
--- a/lib/fwritable.h
+++ b/lib/fwritable.h
@@ -22,7 +22,7 @@
    STREAM must not be wide-character oriented.
    The result doesn't change until the stream is closed or re-opened.  */
 
-#if HAVE___FWRITABLE /* glibc >= 2.2, Solaris >= 7 */
+#if HAVE___FWRITABLE /* glibc >= 2.2, Solaris >= 7, musl libc */
 
 # include <stdio_ext.h>
 # define fwritable(stream) (__fwritable (stream) != 0)
diff --git a/lib/fwriting.h b/lib/fwriting.h
index 07da49b6aa..13415b9152 100644
--- a/lib/fwriting.h
+++ b/lib/fwriting.h
@@ -33,7 +33,7 @@
 
    STREAM must not be wide-character oriented.  */
 
-#if HAVE___FWRITING /* glibc >= 2.2, Solaris >= 7 */
+#if HAVE___FWRITING /* glibc >= 2.2, Solaris >= 7, musl libc */
 
 # include <stdio_ext.h>
 # define fwriting(stream) (__fwriting (stream) != 0)