libc: add fallocate() and fallocate64()

We add the Linux-specific function fallocate() which allows the user to
directly manipulate allocate space for a file.  fallocate() can operate
in different modes, but the default mode is equivalent to posix_fallocate()
which is specified in POSIX.1.

Recent releases of e2fsprogs 1.42.11 and above expect fallocate64() to be
available.

Signed-off-by: Anthony G. Basile <blueness@gentoo.org>
Signed-off-by: Bernhard Reutner-Fischer <rep.dot.nop@gmail.com>

extra/Configs/Config.in

@@ -1014,8 +1014,8 @@ config UCLIBC_LINUX_SPECIFIC
 	default y
 	help
 	  accept4(), bdflush(),
-	  capget(), capset(), eventfd(), fstatfs(),
-	  inotify_*(), ioperm(), iopl(),
+	  capget(), capset(), eventfd(), fallocate(),
+	  fstatfs(), inotify_*(), ioperm(), iopl(),
 	  madvise(), modify_ldt(), pipe2(), personality(),
 	  prctl()/arch_prctl(), pivot_root(), modify_ldt(),
 	  ppoll(), readahead(), reboot(), remap_file_pages(),

include/fcntl.h

@@ -239,6 +239,38 @@ extern int posix_fallocate64 (int __fd, __off64_t __offset, __off64_t __len);
 # endif
 #endif
 
+#if (defined __UCLIBC_LINUX_SPECIFIC__ && defined __USE_GNU) || defined _LIBC
+/* Reserve storage for the data of a file associated with FD.  This function
+   is Linux-specific.  For the portable version, use posix_fallocate().
+   Unlike the latter, fallocate can operate in different modes.  The default
+   mode = 0 is equivalent to posix_fallocate().
+
+   Note: These declarations are used in posix_fallocate.c and
+   posix_fallocate64.c, so we expose them internally.
+ */
+
+/* Flags for fallocate's mode.  */
+# define FALLOC_FL_KEEP_SIZE            1 /* Don't extend size of file
+                                             even if offset + len is
+                                             greater than file size.  */
+# define FALLOC_FL_PUNCH_HOLE           2 /* Create a hole in the file.  */
+
+# ifndef __USE_FILE_OFFSET64
+extern int fallocate (int __fd, int __mode, __off_t __offset, __off_t __len);
+# else
+#  ifdef __REDIRECT
+extern int __REDIRECT (fallocate, (int __fd, int __mode, __off64_t __offset,
+				   __off64_t __len),
+		       fallocate64);
+#  else
+#   define fallocate fallocate64
+#  endif
+# endif
+# ifdef __USE_LARGEFILE64
+extern int fallocate64 (int __fd, int __mode, __off64_t __offset, __off64_t __len);
+# endif
+#endif
+
 __END_DECLS
 
 #endif /* fcntl.h  */

libc/sysdeps/linux/common/Makefile.in

@@ -62,6 +62,10 @@ CSRC-$(UCLIBC_LINUX_SPECIFIC) += \
 	vmsplice.c
 CSRC-$(if $(findstring yy,$(UCLIBC_LINUX_SPECIFIC)$(UCLIBC_HAS_LFS)),y) += \
 	sendfile64.c
+# posix_fallocate() needs __libc_fallocate() from fallocate.c
+# posix_fallocate64() needs __libc_fallocate64() from fallocate64.c
+CSRC-$(if $(UCLIBC_LINUX_SPECIFIC)$(UCLIBC_HAS_ADVANCED_REALTIME),y,) += \
+	fallocate.c $(filter fallocate64.c,$(CSRC-y))
 # NPTL needs these internally: madvise.c
 CSRC-$(findstring y,$(UCLIBC_LINUX_SPECIFIC)$(UCLIBC_HAS_THREADS_NATIVE)) += madvise.c
 ifeq ($(UCLIBC_HAS_THREADS_NATIVE),y)

libc/sysdeps/linux/common/fallocate.c

@@ -0,0 +1,48 @@
+/* vi: set sw=4 ts=4: */
+/*
+ * fallocate() for uClibc - Based off of posix_fallocate() by Erik Andersen
+ * http://www.opengroup.org/onlinepubs/9699919799/functions/posix_fallocate.html
+ *
+ * Copyright (C) 2000-2006 Erik Andersen <andersen@uclibc.org>
+ *
+ * Licensed under the LGPL v2.1 or later, see the file COPYING.LIB in this tarball.
+ */
+
+#include <sys/syscall.h>
+#include <fcntl.h>
+#include <bits/kernel-features.h>
+#include <stdint.h>
+
+#if defined __NR_fallocate
+extern __typeof(fallocate) __libc_fallocate attribute_hidden;
+int attribute_hidden __libc_fallocate(int fd, int mode, __off_t offset, __off_t len)
+{
+	int ret;
+
+# if __WORDSIZE == 32
+	uint32_t off_low = offset;
+	uint32_t len_low = len;
+	/* may assert that these >>31 are 0 */
+	uint32_t zero = 0;
+	INTERNAL_SYSCALL_DECL(err);
+	ret = (int) (INTERNAL_SYSCALL(fallocate, err, 6, fd, mode,
+		__LONG_LONG_PAIR (zero, off_low),
+		__LONG_LONG_PAIR (zero, len_low)));
+# elif __WORDSIZE == 64
+	INTERNAL_SYSCALL_DECL(err);
+	ret = (int) (INTERNAL_SYSCALL(fallocate, err, 4, fd, mode, offset, len));
+# else
+# error your machine is neither 32 bit or 64 bit ... it must be magical
+# endif
+	if (unlikely(INTERNAL_SYSCALL_ERROR_P (ret, err)))
+		return INTERNAL_SYSCALL_ERRNO (ret, err);
+	return 0;
+}
+
+# if defined __UCLIBC_LINUX_SPECIFIC__ && defined __USE_GNU
+strong_alias(__libc_fallocate,fallocate)
+#  if __WORDSIZE == 64
+strong_alias(__libc_fallocate,fallocate64)
+#  endif
+# endif
+#endif

libc/sysdeps/linux/common/fallocate64.c

@@ -0,0 +1,42 @@
+/* vi: set sw=4 ts=4: */
+/*
+ * fallocate() for uClibc - based off posix_fallocate() by Erik Andersen
+ * http://www.opengroup.org/onlinepubs/9699919799/functions/posix_fallocate.html
+ *
+ * Copyright (C) 2000-2006 Erik Andersen <andersen@uclibc.org>
+ *
+ * Licensed under the LGPL v2.1 or later, see the file COPYING.LIB in this tarball.
+ */
+
+#include <sys/syscall.h>
+
+#include <fcntl.h>
+#include <bits/kernel-features.h>
+#include <stdint.h>
+
+#if defined __NR_fallocate
+
+# if __WORDSIZE == 64
+/* Can use normal fallocate() */
+# elif __WORDSIZE == 32
+extern __typeof(fallocate64) __libc_fallocate64 attribute_hidden;
+int attribute_hidden __libc_fallocate64(int fd, int mode, __off64_t offset,
+		__off64_t len)
+{
+	int ret;
+	INTERNAL_SYSCALL_DECL(err);
+	ret = (int) (INTERNAL_SYSCALL(fallocate, err, 6, fd, mode,
+		OFF64_HI_LO (offset), OFF64_HI_LO (len)));
+	if (unlikely(INTERNAL_SYSCALL_ERROR_P (ret, err)))
+		return INTERNAL_SYSCALL_ERRNO (ret, err);
+	return 0;
+}
+
+#  if defined __UCLIBC_LINUX_SPECIFIC__ && defined __USE_GNU
+strong_alias(__libc_fallocate64,fallocate64)
+#  endif
+
+# else
+# error your machine is neither 32 bit or 64 bit ... it must be magical
+# endif
+#endif

libc/sysdeps/linux/common/posix_fallocate.c

@@ -14,28 +14,10 @@
 #include <stdint.h>
 
 #if defined __NR_fallocate
+extern __typeof(fallocate) __libc_fallocate attribute_hidden;
 int posix_fallocate(int fd, __off_t offset, __off_t len)
 {
-	int ret;
-
-# if __WORDSIZE == 32
-	uint32_t off_low = offset;
-	uint32_t len_low = len;
-	/* may assert that these >>31 are 0 */
-	uint32_t zero = 0;
-	INTERNAL_SYSCALL_DECL(err);
-	ret = (int) (INTERNAL_SYSCALL(fallocate, err, 6, fd, 0,
-		__LONG_LONG_PAIR (zero, off_low),
-		__LONG_LONG_PAIR (zero, len_low)));
-# elif __WORDSIZE == 64
-	INTERNAL_SYSCALL_DECL(err);
-	ret = (int) (INTERNAL_SYSCALL(fallocate, err, 4, fd, 0, offset, len));
-# else
-# error your machine is neither 32 bit or 64 bit ... it must be magical
-#endif
-    if (unlikely(INTERNAL_SYSCALL_ERROR_P (ret, err)))
-      return INTERNAL_SYSCALL_ERRNO (ret, err);
-    return 0;
+	return __libc_fallocate(fd, 0, offset, len);
 }
 # if defined __UCLIBC_HAS_LFS__ && __WORDSIZE == 64
 strong_alias(posix_fallocate,posix_fallocate64)

libc/sysdeps/linux/common/posix_fallocate64.c

@@ -14,21 +14,15 @@
 #include <stdint.h>
 
 #if defined __NR_fallocate
-
 # if __WORDSIZE == 64
 /* Can use normal posix_fallocate() */
 # elif __WORDSIZE == 32
+extern __typeof(fallocate64) __libc_fallocate64 attribute_hidden;
 int posix_fallocate64(int fd, __off64_t offset, __off64_t len)
 {
-	int ret;
-	INTERNAL_SYSCALL_DECL(err);
-	ret = (int) (INTERNAL_SYSCALL(fallocate, err, 6, fd, 0,
-		OFF64_HI_LO (offset), OFF64_HI_LO (len)));
-    if (unlikely(INTERNAL_SYSCALL_ERROR_P (ret, err)))
-      return INTERNAL_SYSCALL_ERRNO (ret, err);
-    return 0;
+	return __libc_fallocate64(fd, 0, offset, len);
 }
 # else
-# error your machine is neither 32 bit or 64 bit ... it must be magical
+#  error your machine is neither 32 bit or 64 bit ... it must be magical
 # endif
 #endif

test/.gitignore

@@ -320,6 +320,8 @@ unistd/getcwd
 unistd/getopt
 unistd/getopt_long
 unistd/tstgetopt
+unistd/tst-fallocate
+unistd/tst-fallocate64
 unistd/tst-posix_fallocate
 unistd/tst-posix_fallocate64
 unistd/tst-preadwrite

test/unistd/Makefile.in

@@ -1,12 +1,22 @@
 # uClibc unistd tests
 # Licensed under the LGPL v2.1, see the file COPYING.LIB in this tarball.
 
+# If LFS is not set, get rid of all *64 tests up front
 ifeq ($(UCLIBC_HAS_LFS),)
-TESTS_DISABLED := tst-preadwrite64 tst-posix_fallocate64
+TESTS_DISABLED := tst-preadwrite64 tst-posix_fallocate64 tst-fallocate64
 endif
+
+# If we don't have LINUX_SPECIFIC, then get rid of tst-fallocate
+ifeq ($(UCLIBC_LINUX_SPECIFIC),)
+TESTS_DISABLED += tst-fallocate
+endif
+
+# The logic is similar for HAS_ADVANCED_REALTIME and
+# tst-posix_fallocate/tst-posix_fallocate64
 ifeq ($(UCLIBC_HAS_ADVANCED_REALTIME),)
 TESTS_DISABLED += tst-posix_fallocate
 endif
+
 OPTS_getopt      := -abcXXX -9
 OPTS_getopt_long := --add XXX --delete YYY --verbose
 ifeq ($(UCLIBC_HAS_GNU_GETOPT),y)

test/unistd/tst-fallocate.c

@@ -0,0 +1,166 @@
+#include <fcntl.h>
+#include <sys/stat.h>
+
+#ifndef TST_FALLOCATE64
+# define stat64 stat
+# define fstat64 fstat
+# else
+# ifndef O_LARGEFILE
+#  error no O_LARGEFILE but you want to test with LFS enabled
+# endif
+#endif
+
+static void do_prepare(void);
+static int do_test(void);
+#define PREPARE(argc, argv) do_prepare ()
+#define TEST_FUNCTION do_test ()
+#include <test-skeleton.c>
+
+static int fd;
+static void
+do_prepare (void)
+{
+  fd = create_temp_file ("tst-fallocate.", NULL);
+  if (fd == -1)
+    {
+      printf ("cannot create temporary file: %m\n");
+      exit (1);
+    }
+}
+
+
+static int
+do_test (void)
+{
+  struct stat64 st;
+  int c;
+  char garbage[4096];
+  blkcnt_t blksb4;
+
+  if (fstat64 (fd, &st) != 0)
+    {
+      puts ("1st fstat failed");
+      return 1;
+    }
+
+  if (st.st_size != 0)
+    {
+      puts ("file not created with size 0");
+      return 1;
+    }
+
+  /* This is the default mode which is identical to posix_fallocate().
+     Note: we need a few extra blocks for FALLOC_FL_PUNCH_HOLE below.
+     While block sizes vary, we'll assume eight 4K blocks for good measure. */
+  if (fallocate (fd, 0, 8 * 4096, 128) != 0)
+    {
+      puts ("1st fallocate call failed");
+      return 1;
+    }
+
+  if (fstat64 (fd, &st) != 0)
+    {
+      puts ("2nd fstat failed");
+      return 1;
+    }
+
+  if (st.st_size != 8 * 4096 + 128)
+    {
+      printf ("file size after 1st fallocate call is %llu, expected %u\n",
+	      (unsigned long long int) st.st_size, 8u * 4096u + 128u);
+      return 1;
+    }
+
+  /* Without FALLOC_FL_KEEP_SIZE, this would increaste the size of the file. */
+  if (fallocate (fd, FALLOC_FL_KEEP_SIZE, 0, 16 * 4096) != 0)
+    {
+      puts ("2nd fallocate call failed");
+      return 1;
+    }
+
+  if (fstat64 (fd, &st) != 0)
+    {
+      puts ("3rd fstat failed");
+      return 1;
+    }
+
+  if (st.st_size != 8 * 4096 + 128)
+    {
+      printf ("file size changed in 2nd fallocate call to %llu, expected %u\n",
+	      (unsigned long long int) st.st_size, 8u * 4096u + 128u);
+      return 1;
+    }
+
+  /* Let's fill up the first eight 4k blocks with 'x' to force some allocations. */
+
+  memset(garbage, 'x', 4096);
+  for(c=0; c < 8; c++)
+    if(write(fd, garbage, 4096) == -1)
+      {
+        puts ("write failed");
+        return 1;
+      }
+
+  if (fstat64 (fd, &st) != 0)
+    {
+      puts ("4th fstat failed");
+      return 1;
+    }
+
+  blksb4 = st.st_blocks;
+
+  /* Let's punch a hole in the entire file, turning it effectively into a sparse file. */
+  if (fallocate (fd, FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE, 0, 8 * 4096 + 128) != 0)
+    {
+      puts ("3rd fallocate call failed");
+      return 1;
+    }
+
+  if (fstat64 (fd, &st) != 0)
+    {
+      puts ("5th fstat failed");
+      return 1;
+    }
+
+  if (st.st_size != 8 * 4096 + 128)
+    {
+      printf ("file size after 3rd fallocate call is %llu, expected %u\n",
+	      (unsigned long long int) st.st_size, 8u * 4096u + 128u);
+      return 1;
+    }
+
+  /* The number of allocated blocks should decrease.  I hope this works on
+     all filesystems! */
+  if (st.st_blocks >= blksb4)
+    {
+      printf ("number of blocks after 3rd fallocate call is %lu, expected less than %lu\n",
+	      (unsigned long int) st.st_blocks, blksb4);
+      return 1;
+    }
+
+#ifdef TST_FALLOCATE64
+  /* We'll just do a mode = 0 test for fallocate64() */
+  if (fallocate64 (fd, 0, 4097ULL, 4294967295ULL + 2ULL) != 0)
+    {
+      puts ("1st fallocate64 call failed");
+      return 1;
+    }
+
+  if (fstat64 (fd, &st) != 0)
+    {
+      puts ("6th fstat failed");
+      return 1;
+    }
+
+  if (st.st_size != 4097ULL + 4294967295ULL + 2ULL)
+    {
+      printf ("file size after 1st fallocate64 call is %llu, expected %llu\n",
+	      (unsigned long long int) st.st_size, 4097ULL + 4294967295ULL + 2ULL);
+      return 1;
+    }
+#endif
+  close (fd);
+
+  return 0;
+}
+

test/unistd/tst-fallocate64.c

@@ -0,0 +1,2 @@
+#define TST_FALLOCATE64
+#include "tst-fallocate.c"