linux-user: Add strace support for printing arguments of fallocate()

This patch implements strace argument printing functionality for following syscall:

    *fallocate - manipulate file space

        int fallocate(int fd, int mode, off_t offset, off_t len)
        man page: https://www.man7.org/linux/man-pages/man2/fallocate.2.html

Implementation notes:

    This syscall's second argument "mode" is composed of predefined values
    which represent flags that determine the type of operation that is
    to be performed on the file space. For that reason, a printing
    function "print_fallocate" was stated in file "strace.list". This printing
    function uses an already existing function "print_flags()" to print flags of
    the "mode" argument. These flags are stated inside an array "falloc_flags"
    that contains values of type "struct flags". These values are instantiated
    using an existing macro "FLAG_GENERIC()". Most of these flags are defined
    after kernel version 3.0 which is why they are enwrapped in an #ifdef
    directive.
    The syscall's third ant fourth argument are of type "off_t" which can
    cause variations between 32/64-bit architectures. To handle this variation,
    function "target_offset64()" was copied from file "strace.c" and used in
    "print_fallocate" to print "off_t" arguments for 32-bit architectures.

Signed-off-by: Filip Bozuta <Filip.Bozuta@syrmia.com>
Reviewed-by: Laurent Vivier <laurent@vivier.eu>
Message-Id: <20200619123331.17387-7-filip.bozuta@syrmia.com>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>

1 files changed, 16 insertions, 0 deletions

diff --git a/linux-user/qemu.h b/linux-user/qemu.h
index 8f938b8105..be67391ba4 100644
--- a/linux-user/qemu.h
+++ b/linux-user/qemu.h
@@ -670,6 +670,22 @@ static inline int is_error(abi_long ret)
     return (abi_ulong)ret >= (abi_ulong)(-4096);
 }
 
+#if TARGET_ABI_BITS == 32
+static inline uint64_t target_offset64(uint32_t word0, uint32_t word1)
+{
+#ifdef TARGET_WORDS_BIGENDIAN
+    return ((uint64_t)word0 << 32) | word1;
+#else
+    return ((uint64_t)word1 << 32) | word0;
+#endif
+}
+#else /* TARGET_ABI_BITS == 32 */
+static inline uint64_t target_offset64(uint64_t word0, uint64_t word1)
+{
+    return word0;
+}
+#endif /* TARGET_ABI_BITS != 32 */
+
 /**
  * preexit_cleanup: housekeeping before the guest exits
  *