[Qemu-devel] [PATCH v6 2/8] New -mem-path option - unlink.

[Antonios Motakis <a.motakis@virtualopensystems.com>]

The unlink option allows the created file to be externally deleted
after QEMU is terminated.

 - unlink=on|off - default on, unlink the file after opening it

Signed-off-by: Antonios Motakis <a.motakis@virtualopensystems.com>
Signed-off-by: Nikolay Nikolaev <n.nikolaev@virtualopensystems.com>
---
 exec.c          | 18 +++++++++++++-----
 qemu-options.hx |  7 ++++---
 vl.c            |  4 ++++
 3 files changed, 21 insertions(+), 8 deletions(-)

diff --git a/exec.c b/exec.c
index 1c40a0d..30f4019 100644
--- a/exec.c
+++ b/exec.c
@@ -999,7 +999,7 @@ static void *file_ram_alloc(RAMBlock *block,
     int flags;
     unsigned long hpagesize;
     QemuOpts *opts;
-    unsigned int mem_prealloc = 0, mem_share = 0;
+    unsigned int mem_prealloc = 0, mem_share = 0, mem_unlink = 1;
 
     hpagesize = gethugepagesize(path);
     if (!hpagesize) {
@@ -1020,6 +1020,7 @@ static void *file_ram_alloc(RAMBlock *block,
     if (opts) {
         mem_prealloc = qemu_opt_get_bool(opts, "prealloc", 0);
         mem_share = qemu_opt_get_bool(opts, "share", 0);
+        mem_unlink = qemu_opt_get_bool(opts, "unlink", 1);
     }
 
     /* Make name safe to use with mkstemp by replacing '/' with '_'. */
@@ -1029,18 +1030,25 @@ static void *file_ram_alloc(RAMBlock *block,
             *c = '_';
     }
 
-    filename = g_strdup_printf("%s/qemu_back_mem.%s.XXXXXX", path,
-                               sanitized_name);
+    filename = g_strdup_printf("%s/qemu_back_mem.%s%s", path, sanitized_name,
+                               (mem_unlink) ? ".XXXXXX" : "");
     g_free(sanitized_name);
 
-    fd = mkstemp(filename);
+    if (mem_unlink) {
+        fd = mkstemp(filename);
+    } else {
+        fd = open(filename, O_CREAT | O_RDWR | O_EXCL,
+                S_IRWXU | S_IRWXG | S_IRWXO);
+    }
     if (fd < 0) {
         perror("unable to create guest RAM backing store");
         g_free(filename);
         return NULL;
     }
 
-    unlink(filename);
+    if (mem_unlink) {
+        unlink(filename);
+    }
     g_free(filename);
 
     memory = (memory + hpagesize - 1) & ~(hpagesize - 1);
diff --git a/qemu-options.hx b/qemu-options.hx
index 60ecc95..a12af97 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -221,14 +221,15 @@ gigabytes respectively.
 ETEXI
 
 DEF("mem-path", HAS_ARG, QEMU_OPTION_mempath,
-    "-mem-path [path=]path[,prealloc=on|off][,share=on|off]\n"
+    "-mem-path [path=]path[,prealloc=on|off][,share=on|off][,unlink=on|off]\n"
     "                provide backing storage for guest RAM\n"
     "                path= a directory path for the backing store\n"
     "                prealloc= preallocate guest memory [default disabled]\n"
-    "                share= enable mmap share flag [default disabled]\n",
+    "                share= enable mmap share flag [default disabled]\n"
+    "                unlink= enable unlinking the guest RAM files [default enabled]\n",
         QEMU_ARCH_ALL)
 STEXI
-@item -mem-path [path=]@var{path}[,prealloc=on|off][,share=on|off]
+@item -mem-path [path=]@var{path}[,prealloc=on|off][,share=on|off][,unlink=on|off]
 @findex -mem-path
 Allocate guest RAM from a temporarily created file in @var{path}.
 ETEXI
diff --git a/vl.c b/vl.c
index e98abc8..5034bb6 100644
--- a/vl.c
+++ b/vl.c
@@ -546,6 +546,10 @@ static QemuOptsList qemu_mem_path_opts = {
             .name = "share",
             .type = QEMU_OPT_BOOL,
         },
+        {
+            .name = "unlink",
+            .type = QEMU_OPT_BOOL,
+        },
         { /* end of list */ }
     },
 };
-- 
1.8.3.2