All of lore.kernel.org
 help / color / mirror / Atom feed
From: Keno Fischer <keno@juliacomputing.com>
To: qemu-devel@nongnu.org
Cc: Keno Fischer <keno@juliacomputing.com>, groug@kaod.org
Subject: [Qemu-devel] [PATCH v2 17/20] 9p: darwin: Provide a fallback implementation for utimensat
Date: Thu, 31 May 2018 21:26:12 -0400	[thread overview]
Message-ID: <b5c27c58c250088ef6d09bd9321e96d423df02d7.1527814874.git.keno@juliacomputing.com> (raw)
In-Reply-To: <cover.1527814874.git.keno@juliacomputing.com>
In-Reply-To: <cover.1527814874.git.keno@juliacomputing.com>

This function is new in Mac OS 10.13. Provide a fallback implementation
when building against older SDKs. The complication in the definition comes
having to separately handle the used SDK version and the target OS version.

- If the SDK version is too low (__MAC_10_13 not defined), utimensat is not
  defined in the header, so we must not try to use it (doing so would error).
- Otherwise, if the targetted OS version is at least 10.13, we know this
  function is available, so we can unconditionally call it.
- Lastly, we check for the availability of the __builtin_available macro to
  potentially insert a dynamic check for this OS version. However, __builtin_available
  is only available with sufficiently recent versions of clang and while all
  Apple clang versions that ship with Xcode versions that support the 10.13
  SDK support with builtin, we want to allow building with compilers other
  than Apple clang that may not support this builtin.

Signed-off-by: Keno Fischer <keno@juliacomputing.com>
---

Changes from v1:
 * Correct calculation of tv_usec
 * Support UTIME_NOW/UTIME/OMIT
 * Now covers fsdev/virtfs-proxy-helper.c

 fsdev/virtfs-proxy-helper.c |  3 +-
 hw/9pfs/9p-local.c          |  2 +-
 hw/9pfs/9p-util-darwin.c    | 96 +++++++++++++++++++++++++++++++++++++++++++++
 hw/9pfs/9p-util-linux.c     |  6 +++
 hw/9pfs/9p-util.h           |  8 ++++
 hw/9pfs/9p.c                |  1 +
 6 files changed, 113 insertions(+), 3 deletions(-)

diff --git a/fsdev/virtfs-proxy-helper.c b/fsdev/virtfs-proxy-helper.c
index a26f8b8..d8dd3f5 100644
--- a/fsdev/virtfs-proxy-helper.c
+++ b/fsdev/virtfs-proxy-helper.c
@@ -957,8 +957,7 @@ static int process_requests(int sock)
                                      &spec[0].tv_sec, &spec[0].tv_nsec,
                                      &spec[1].tv_sec, &spec[1].tv_nsec);
             if (retval > 0) {
-                retval = utimensat(AT_FDCWD, path.data, spec,
-                                   AT_SYMLINK_NOFOLLOW);
+                retval = utimensat_nofollow(AT_FDCWD, path.data, spec);
                 if (retval < 0) {
                     retval = -errno;
                 }
diff --git a/hw/9pfs/9p-local.c b/hw/9pfs/9p-local.c
index 7830526..47e8580 100644
--- a/hw/9pfs/9p-local.c
+++ b/hw/9pfs/9p-local.c
@@ -1071,7 +1071,7 @@ static int local_utimensat(FsContext *s, V9fsPath *fs_path,
         goto out;
     }
 
-    ret = utimensat(dirfd, name, buf, AT_SYMLINK_NOFOLLOW);
+    ret = utimensat_nofollow(dirfd, name, buf);
     close_preserve_errno(dirfd);
 out:
     g_free(dirpath);
diff --git a/hw/9pfs/9p-util-darwin.c b/hw/9pfs/9p-util-darwin.c
index cdb4c9e..ac414bc 100644
--- a/hw/9pfs/9p-util-darwin.c
+++ b/hw/9pfs/9p-util-darwin.c
@@ -62,3 +62,99 @@ int fsetxattrat_nofollow(int dirfd, const char *filename, const char *name,
     close_preserve_errno(fd);
     return ret;
 }
+
+#ifndef __has_builtin
+#define __has_builtin(x) 0
+#endif
+
+static int update_times_from_stat(int fd, struct timespec times[2],
+                                  int update0, int update1)
+{
+    struct stat buf;
+    int ret = fstat(fd, &buf);
+    if (ret == -1) {
+        return ret;
+    }
+    if (update0) {
+        times[0] = buf.st_atimespec;
+    }
+    if (update1) {
+        times[1] = buf.st_mtimespec;
+    }
+    return 0;
+}
+
+int utimensat_nofollow(int dirfd, const char *filename,
+                       const struct timespec times_in[2])
+{
+    int ret, fd;
+    int special0, special1;
+    struct timeval futimes_buf[2];
+    struct timespec times[2];
+    memcpy(times, times_in, 2 * sizeof(struct timespec));
+
+/* Check whether we have an SDK version that defines utimensat */
+#if defined(__MAC_10_13)
+# if __MAC_OS_X_VERSION_MIN_REQUIRED >= __MAC_10_13
+#  define UTIMENSAT_AVAILABLE 1
+# elif __has_builtin(__builtin_available)
+#  define UTIMENSAT_AVAILABLE __builtin_available(macos 10.13, *)
+# else
+#  define UTIMENSAT_AVAILABLE 0
+# endif
+    if (UTIMENSAT_AVAILABLE) {
+        return utimensat(dirfd, filename, times, AT_SYMLINK_NOFOLLOW);
+    }
+#endif
+
+    /* utimensat not available. Use futimes. */
+    fd = openat_file(dirfd, filename, O_PATH_9P_UTIL | O_NOFOLLOW, 0);
+    if (fd == -1) {
+        return -1;
+    }
+
+    special0 = times[0].tv_nsec == UTIME_OMIT;
+    special1 = times[1].tv_nsec == UTIME_OMIT;
+    if (special0 || special1) {
+        /* If both are set, nothing to do */
+        if (special0 && special1) {
+            ret = 0;
+            goto done;
+        }
+
+        ret = update_times_from_stat(fd, times, special0, special1);
+        if (ret < 0) {
+            goto done;
+        }
+    }
+
+    special0 = times[0].tv_nsec == UTIME_NOW;
+    special1 = times[1].tv_nsec == UTIME_NOW;
+    if (special0 || special1) {
+        ret = futimes(fd, NULL);
+        if (ret < 0) {
+            goto done;
+        }
+
+        /* If both are set, we are done */
+        if (special0 && special1) {
+            ret = 0;
+            goto done;
+        }
+
+        ret = update_times_from_stat(fd, times, special0, special1);
+        if (ret < 0) {
+            goto done;
+        }
+    }
+
+    futimes_buf[0].tv_sec = times[0].tv_sec;
+    futimes_buf[0].tv_usec = times[0].tv_nsec / 1000;
+    futimes_buf[1].tv_sec = times[1].tv_sec;
+    futimes_buf[1].tv_usec = times[1].tv_nsec / 1000;
+    ret = futimes(fd, futimes_buf);
+
+done:
+    close_preserve_errno(fd);
+    return ret;
+}
diff --git a/hw/9pfs/9p-util-linux.c b/hw/9pfs/9p-util-linux.c
index defa3a4..3902378 100644
--- a/hw/9pfs/9p-util-linux.c
+++ b/hw/9pfs/9p-util-linux.c
@@ -57,3 +57,9 @@ int fsetxattrat_nofollow(int dirfd, const char *filename, const char *name,
     g_free(proc_path);
     return ret;
 }
+
+int utimensat_nofollow(int dirfd, const char *filename,
+                       const struct timespec times[2])
+{
+    return utimensat(dirfd, filename, times, AT_SYMLINK_NOFOLLOW);
+}
diff --git a/hw/9pfs/9p-util.h b/hw/9pfs/9p-util.h
index 50a03c7..b1dc08a 100644
--- a/hw/9pfs/9p-util.h
+++ b/hw/9pfs/9p-util.h
@@ -36,6 +36,12 @@ static inline int qemu_lsetxattr(const char *path, const char *name,
 #define qemu_lsetxattr lsetxattr
 #endif
 
+/* Compatibility with old SDK Versions for Darwin */
+#if defined(CONFIG_DARWIN) && !defined(UTIME_NOW)
+#define UTIME_NOW -1
+#define UTIME_OMIT -2
+#endif
+
 static inline void close_preserve_errno(int fd)
 {
     int serrno = errno;
@@ -81,5 +87,7 @@ ssize_t flistxattrat_nofollow(int dirfd, const char *filename,
                               char *list, size_t size);
 ssize_t fremovexattrat_nofollow(int dirfd, const char *filename,
                                 const char *name);
+int utimensat_nofollow(int dirfd, const char *filename,
+                       const struct timespec times[2]);
 
 #endif
diff --git a/hw/9pfs/9p.c b/hw/9pfs/9p.c
index 24802b9..71b2dc9 100644
--- a/hw/9pfs/9p.c
+++ b/hw/9pfs/9p.c
@@ -21,6 +21,7 @@
 #include "virtio-9p.h"
 #include "fsdev/qemu-fsdev.h"
 #include "9p-xattr.h"
+#include "9p-util.h"
 #include "coth.h"
 #include "trace.h"
 #include "migration/blocker.h"
-- 
2.8.1

  parent reply	other threads:[~2018-06-01  1:27 UTC|newest]

Thread overview: 34+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-06-01  1:25 [Qemu-devel] [PATCH v2 00/20] 9p: Add support for Darwin Keno Fischer
2018-06-01  1:25 ` [Qemu-devel] [PATCH v2 01/20] cutils: Provide strchrnul Keno Fischer
2018-06-01  8:15   ` Greg Kurz
2018-06-01  8:46     ` Dr. David Alan Gilbert
2018-06-01 14:15   ` Eric Blake
2018-06-01  1:25 ` [Qemu-devel] [PATCH v2 02/20] 9p: proxy: Fix size passed to `connect` Keno Fischer
2018-06-01  9:09   ` Greg Kurz
2018-06-01  1:25 ` [Qemu-devel] [PATCH v2 03/20] 9p: xattr: Fix crash due to free of uninitialized value Keno Fischer
2018-06-01  9:19   ` Greg Kurz
2018-06-01  1:25 ` [Qemu-devel] [PATCH v2 04/20] 9p: linux: Fix a couple Linux assumptions Keno Fischer
2018-06-01  1:26 ` [Qemu-devel] [PATCH v2 05/20] 9p: Properly set errp in fstatfs error path Keno Fischer
2018-06-01  9:32   ` Greg Kurz
2018-06-01  1:26 ` [Qemu-devel] [PATCH v2 06/20] 9p: Avoid warning if FS_IOC_GETVERSION is not defined Keno Fischer
2018-06-01  9:57   ` Greg Kurz
2018-06-01  1:26 ` [Qemu-devel] [PATCH v2 07/20] 9p: Move a couple xattr functions to 9p-util Keno Fischer
2018-06-01 10:03   ` Greg Kurz
2018-06-01  1:26 ` [Qemu-devel] [PATCH v2 08/20] 9p: Rename 9p-util -> 9p-util-linux Keno Fischer
2018-06-01 10:07   ` Greg Kurz
2018-06-01  1:26 ` [Qemu-devel] [PATCH v2 09/20] 9p: Properly check/translate flags in unlinkat Keno Fischer
2018-06-01 10:13   ` Greg Kurz
2018-06-01  1:26 ` [Qemu-devel] [PATCH v2 10/20] 9p: darwin: Handle struct stat(fs) differences Keno Fischer
2018-06-01  1:26 ` [Qemu-devel] [PATCH v2 11/20] 9p: darwin: Handle struct dirent differences Keno Fischer
2018-06-01  1:26 ` [Qemu-devel] [PATCH v2 12/20] 9p: darwin: Explicitly cast comparisons of mode_t with -1 Keno Fischer
2018-06-29 20:32   ` Eric Blake
2018-06-01  1:26 ` [Qemu-devel] [PATCH v2 13/20] 9p: darwin: Ignore O_{NOATIME, DIRECT} Keno Fischer
2018-06-01  1:26 ` [Qemu-devel] [PATCH v2 14/20] 9p: darwin: Provide a compatibility definition for XATTR_SIZE_MAX Keno Fischer
2018-06-01  1:26 ` [Qemu-devel] [PATCH v2 15/20] 9p: darwin: *xattr_nofollow implementations Keno Fischer
2018-06-01 11:13   ` Greg Kurz
2018-06-02 20:01     ` Keno Fischer
2018-06-01  1:26 ` [Qemu-devel] [PATCH v2 16/20] 9p: darwin: Compatibility for f/l*xattr Keno Fischer
2018-06-01  1:26 ` Keno Fischer [this message]
2018-06-01  1:26 ` [Qemu-devel] [PATCH v2 18/20] 9p: darwin: Implement compatibility for mknodat Keno Fischer
2018-06-01  1:26 ` [Qemu-devel] [PATCH v2 19/20] 9p: darwin: virtfs-proxy: Implement setuid code for darwin Keno Fischer
2018-06-01  1:26 ` [Qemu-devel] [PATCH v2 20/20] 9p: darwin: configure: Allow VirtFS on Darwin Keno Fischer

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=b5c27c58c250088ef6d09bd9321e96d423df02d7.1527814874.git.keno@juliacomputing.com \
    --to=keno@juliacomputing.com \
    --cc=groug@kaod.org \
    --cc=qemu-devel@nongnu.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.