pathconf can't use fpathconf or it will block opening FIFOs

libc/unistd/pathconf.c

@@ -17,32 +17,234 @@
    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
    02111-1307 USA.  */
 
+
+/* It would be great it this could be implemented using fpathconf,
+ * but that doesn't work out very well (think FIFOs and sockets) */
+
 #include <errno.h>
 #include <unistd.h>
 #include <limits.h>
+#include <sys/statfs.h>
 #include <errno.h>
 #include <stddef.h>
 #include <unistd.h>
 #include <limits.h>
 #include <fcntl.h>
+#include <sys/stat.h>
+#include <sys/statfs.h>
+//#include <sys/statvfs.h>
+
+//#include "linux_fsinfo.h"
+
+
+/* The Linux kernel headers mention this as a kind of generic value.  */
+#define LINUX_LINK_MAX	127
 
 
 /* Get file-specific information about descriptor FD.  */
 long int pathconf(const char *path, int name)
 {
-    int fd;
-
     if (path[0] == '\0')
     {
 	__set_errno (ENOENT);
 	return -1;
     }
 
-    fd = open(path, O_RDONLY); 
-    if (fd < 0) {
-	__set_errno (ENOENT);
-	return -1;
+    if (name == _PC_LINK_MAX)
+    {
+	/* Cut some corners */
+#if 0
+	struct statfs fsbuf;
+
+	/* Determine the filesystem type.  */
+	if (statfs (path, &fsbuf) < 0)
+	{
+	    if (errno == ENOSYS)
+		/* not possible, return the default value.  */
+		return LINUX_LINK_MAX;
+
+	    /* Some error occured.  */
+	    return -1;
+	}
+
+	switch (fsbuf.f_type)
+	{
+	    case EXT2_SUPER_MAGIC:
+		return EXT2_LINK_MAX;
+
+	    case MINIX_SUPER_MAGIC:
+	    case MINIX_SUPER_MAGIC2:
+		return MINIX_LINK_MAX;
+
+	    case MINIX2_SUPER_MAGIC:
+	    case MINIX2_SUPER_MAGIC2:
+		return MINIX2_LINK_MAX;
+
+	    case XENIX_SUPER_MAGIC:
+		return XENIX_LINK_MAX;
+
+	    case SYSV4_SUPER_MAGIC:
+	    case SYSV2_SUPER_MAGIC:
+		return SYSV_LINK_MAX;
+
+	    case COH_SUPER_MAGIC:
+		return COH_LINK_MAX;
+
+	    case UFS_MAGIC:
+	    case UFS_CIGAM:
+		return UFS_LINK_MAX;
+
+	    case REISERFS_SUPER_MAGIC:
+		return REISERFS_LINK_MAX;
+
+	    default:
+		return LINUX_LINK_MAX;
+	}
+#else
+	return LINUX_LINK_MAX;
+#endif
     }
-    return (fpathconf(fd, name));
+
+    switch (name)
+    {
+	default:
+	    __set_errno (EINVAL);
+	    return -1;
+
+	case _PC_MAX_CANON:
+#ifdef	MAX_CANON
+	    return MAX_CANON;
+#else
+	    return -1;
+#endif
+
+	case _PC_MAX_INPUT:
+#ifdef	MAX_INPUT
+	    return MAX_INPUT;
+#else
+	    return -1;
+#endif
+
+	case _PC_NAME_MAX:
+#ifdef	NAME_MAX
+	    {
+		struct statfs buf;
+		int save_errno = errno;
+
+		if (statfs (path, &buf) < 0)
+		{
+		    if (errno == ENOSYS)
+		    {
+			errno = save_errno;
+			return NAME_MAX;
+		    }
+		    return -1;
+		}
+		else
+		{
+#ifdef _STATFS_F_NAMELEN
+		    return buf.f_namelen;
+#else
+# ifdef _STATFS_F_NAME_MAX
+		    return buf.f_name_max;
+# else
+		    return NAME_MAX;
+# endif
+#endif
+		}
+	    }
+#else
+	    return -1;
+#endif
+
+	case _PC_PATH_MAX:
+#ifdef	PATH_MAX
+	    return PATH_MAX;
+#else
+	    return -1;
+#endif
+
+	case _PC_PIPE_BUF:
+#ifdef	PIPE_BUF
+	    return PIPE_BUF;
+#else
+	    return -1;
+#endif
+
+	case _PC_CHOWN_RESTRICTED:
+#ifdef	_POSIX_CHOWN_RESTRICTED
+	    return _POSIX_CHOWN_RESTRICTED;
+#else
+	    return -1;
+#endif
+
+	case _PC_NO_TRUNC:
+#ifdef	_POSIX_NO_TRUNC
+	    return _POSIX_NO_TRUNC;
+#else
+	    return -1;
+#endif
+
+	case _PC_VDISABLE:
+#ifdef	_POSIX_VDISABLE
+	    return _POSIX_VDISABLE;
+#else
+	    return -1;
+#endif
+
+	case _PC_SYNC_IO:
+#ifdef	_POSIX_SYNC_IO
+	    return _POSIX_SYNC_IO;
+#else
+	    return -1;
+#endif
+
+	case _PC_ASYNC_IO:
+#if defined _POSIX_ASYNC_IO && defined __UCLIBC_HAVE_LFS__ 
+	    {
+		/* AIO is only allowed on regular files and block devices.  */
+		struct stat st;
+
+		if (stat (path, &st) < 0 || (! S_ISREG (st.st_mode) && ! S_ISBLK (st.st_mode)))
+		    return -1;
+		else
+		    return 1;
+	    }
+#else
+	    return -1;
+#endif
+
+	case _PC_PRIO_IO:
+#ifdef	_POSIX_PRIO_IO
+	    return _POSIX_PRIO_IO;
+#else
+	    return -1;
+#endif
+
+	case _PC_SOCK_MAXBUF:
+#ifdef	SOCK_MAXBUF
+	    return SOCK_MAXBUF;
+#else
+	    return -1;
+#endif
+
+	case _PC_FILESIZEBITS:
+#ifdef FILESIZEBITS
+	    return FILESIZEBITS;
+#else
+	    /* We let platforms with larger file sizes overwrite this value.  */
+	    return 32;
+#endif
+
+	    /* Be lazy -- skip these */
+	case _PC_REC_INCR_XFER_SIZE:
+	case _PC_REC_MAX_XFER_SIZE:
+	case _PC_REC_MIN_XFER_SIZE:
+	case _PC_REC_XFER_ALIGN:
+	case _PC_ALLOC_SIZE_MIN:
+	case _PC_SYMLINK_MAX:
+	    return -1;
+    }
+
 }