Merge remote-tracking branch 'remotes/bonzini/tags/for-upstream' into staging

* configure fix for environment variables (Daniel)
* fix memory leaks (Alex)
* x86_64 MTTCG fixes (Emilio)
* introduce atomic64 (Emilio)
* Fix for virtio hang (Fam, myself)
* SH serial port fix (Geert)
* Deprecate rotation_rate for scsi-block (Fam)
* Extend memory-backend-file availability to all POSIX hosts (Hikaru)
* Memory API cleanups and fixes (Igor, Li Qiang, Peter, Philippe)
* MSI/IOMMU fix (Jan)
* Socket reconnection fixes (Marc-André)
* icount fixes (Emilio, myself)
* QSP fixes for Coverity (myself)
* Some record/replay improovements (Pavel)
* Packed struct fixes (Peter)
* Windows dump fixes and elf2dmp (Viktor)
* kbmclock fix (Yongji)

# gpg: Signature made Tue 02 Oct 2018 18:13:12 BST
# gpg:                using RSA key BFFBD25F78C7AE83
# gpg: Good signature from "Paolo Bonzini <bonzini@gnu.org>"
# gpg:                 aka "Paolo Bonzini <pbonzini@redhat.com>"
# Primary key fingerprint: 46F5 9FBD 57D6 12E7 BFD4  E2F7 7E15 100C CD36 69B1
#      Subkey fingerprint: F133 3857 4B66 2389 866C  7682 BFFB D25F 78C7 AE83

* remotes/bonzini/tags/for-upstream: (80 commits)
  hw/scsi/mptendian: Avoid taking address of fields in packed structs
  cpus: fix TCG kick timer leak
  docs/devel/memory.txt: Document _with_attrs accessors
  hw/nvram/fw_cfg: Use memberwise copy of MemoryRegionOps struct
  memory: Remove old_mmio accessors
  memory: Fix access_with_adjusted_size(small size) on big-endian memory regions
  memory: Refactor common shifting code from accessors
  memory: Use MAKE_64BIT_MASK()
  virtio: do not take address of packed members
  replay: replay BH for IDE trim operation
  hostmem-file: make available memory-backend-file on POSIX-based hosts
  target/i386: fix translation for icount mode
  hvf: drop unused variable
  qom/object: add some interface asserts
  accel/tcg: Remove dead code
  lsi53c895a: convert to trace-events
  scsi-block: Deprecate rotation_rate
  kvmclock: run KVM_KVMCLOCK_CTRL ioctl in vcpu thread
  MAINTAINERS: add myself as elf2dmp maintainer
  contrib: add elf2dmp tool
  ...

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

1 files changed, 73 insertions, 0 deletions

diff --git a/util/oslib-posix.c b/util/oslib-posix.c
index 13b6f8d..fbd0dc8 100644
--- a/util/oslib-posix.c
+++ b/util/oslib-posix.c
@@ -88,6 +88,79 @@ int qemu_daemon(int nochdir, int noclose)
     return daemon(nochdir, noclose);
 }
 
+bool qemu_write_pidfile(const char *path, Error **errp)
+{
+    int fd;
+    char pidstr[32];
+
+    while (1) {
+        struct stat a, b;
+        struct flock lock = {
+            .l_type = F_WRLCK,
+            .l_whence = SEEK_SET,
+            .l_len = 0,
+        };
+
+        fd = qemu_open(path, O_CREAT | O_WRONLY, S_IRUSR | S_IWUSR);
+        if (fd == -1) {
+            error_setg_errno(errp, errno, "Cannot open pid file");
+            return false;
+        }
+
+        if (fstat(fd, &b) < 0) {
+            error_setg_errno(errp, errno, "Cannot stat file");
+            goto fail_close;
+        }
+
+        if (fcntl(fd, F_SETLK, &lock)) {
+            error_setg_errno(errp, errno, "Cannot lock pid file");
+            goto fail_close;
+        }
+
+        /*
+         * Now make sure the path we locked is the same one that now
+         * exists on the filesystem.
+         */
+        if (stat(path, &a) < 0) {
+            /*
+             * PID file disappeared, someone else must be racing with
+             * us, so try again.
+             */
+            close(fd);
+            continue;
+        }
+
+        if (a.st_ino == b.st_ino) {
+            break;
+        }
+
+        /*
+         * PID file was recreated, someone else must be racing with
+         * us, so try again.
+         */
+        close(fd);
+    }
+
+    if (ftruncate(fd, 0) < 0) {
+        error_setg_errno(errp, errno, "Failed to truncate pid file");
+        goto fail_unlink;
+    }
+
+    snprintf(pidstr, sizeof(pidstr), FMT_pid "\n", getpid());
+    if (write(fd, pidstr, strlen(pidstr)) != strlen(pidstr)) {
+        error_setg(errp, "Failed to write pid file");
+        goto fail_unlink;
+    }
+
+    return true;
+
+fail_unlink:
+    unlink(path);
+fail_close:
+    close(fd);
+    return false;
+}
+
 void *qemu_oom_check(void *ptr)
 {
     if (ptr == NULL) {