[PATCH v1] util: OpenBSD build fix

[PATCH v1] util: OpenBSD build fix

[David CARLIER]

From e2103b86b031ab74ff4c8dd0a3944cb488c9333e Mon Sep 17 00:00:00 2001
From: David Carlier <devnexen@gmail.com>
Date: Tue, 14 Jul 2020 21:34:59 +0100
Subject: [PATCH] util: OpenBSD build fix.

thread id implementation, using getthrid syscall.
qemu_exec_dir implementation as beast as we can as
path is not always possible to resolve this on this platform.

Signed-off-by: David Carlier <devnexen@gmail.com>
---
 util/oslib-posix.c | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/util/oslib-posix.c b/util/oslib-posix.c
index 72907d4d7f..4a0cce15b4 100644
--- a/util/oslib-posix.c
+++ b/util/oslib-posix.c
@@ -56,6 +56,10 @@
 #include <lwp.h>
 #endif

+#ifdef __OpenBSD__
+#include <sys/sysctl.h>
+#endif
+
 #ifdef __APPLE__
 #include <mach-o/dyld.h>
 #endif
@@ -100,6 +104,8 @@ int qemu_get_thread_id(void)
     return (int)tid;
 #elif defined(__NetBSD__)
     return _lwp_self();
+#elif defined(__OpenBSD__)
+    return getthrid();
 #else
     return getpid();
 #endif
@@ -408,6 +414,23 @@ void qemu_init_exec_dir(const char *argv0)
             }
         }
     }
+#elif defined(__OpenBSD__)
+    {
+
+        char **args;
+        size_t len;
+        int mib[4] = {CTL_KERN, KERN_PROC_ARGS, getpid(), KERN_PROC_ARGV};
+
+        *buf = 0;
+        if (!sysctl(mib, ARRAY_SIZE(mib), NULL, &len, NULL, 0)) {
+            args = malloc(len);
+            if (!sysctl(mib, ARRAY_SIZE(mib), args, &len, NULL, 0)) {
+                p = realpath(*args, buf);
+            }
+
+            free(args);
+        }
+    }
 #endif
     /* If we don't have any way of figuring out the actual executable
        location then try argv[0].  */
-- 
2.27.0

Re: [PATCH v1] util: OpenBSD build fix

[Peter Maydell]

On Tue, 14 Jul 2020 at 20:45, David CARLIER <devnexen@gmail.com> wrote:
>
> From e2103b86b031ab74ff4c8dd0a3944cb488c9333e Mon Sep 17 00:00:00 2001
> From: David Carlier <devnexen@gmail.com>
> Date: Tue, 14 Jul 2020 21:34:59 +0100
> Subject: [PATCH] util: OpenBSD build fix.
>
> thread id implementation, using getthrid syscall.
> qemu_exec_dir implementation as beast as we can as
> path is not always possible to resolve this on this platform.

Hi; thanks for the patch.

These look like two separate changes, so they should be
in separate patches, please.

It would be useful to have a comment in the code documenting
what the limitations of the OpenBSD call are, and when
it's better than just using realpath() on the argv[0]
that we already have. (ie, in which cases is the argv[0]
which we get back via KERN_PROC_ARGV something other than
the argv[0] that was passed to the process?)

> Signed-off-by: David Carlier <devnexen@gmail.com>
> ---
>  util/oslib-posix.c | 23 +++++++++++++++++++++++
>  1 file changed, 23 insertions(+)
>
> diff --git a/util/oslib-posix.c b/util/oslib-posix.c
> index 72907d4d7f..4a0cce15b4 100644
> --- a/util/oslib-posix.c
> +++ b/util/oslib-posix.c
> @@ -56,6 +56,10 @@
>  #include <lwp.h>
>  #endif
>
> +#ifdef __OpenBSD__
> +#include <sys/sysctl.h>
> +#endif
> +
>  #ifdef __APPLE__
>  #include <mach-o/dyld.h>
>  #endif
> @@ -100,6 +104,8 @@ int qemu_get_thread_id(void)
>      return (int)tid;
>  #elif defined(__NetBSD__)
>      return _lwp_self();
> +#elif defined(__OpenBSD__)
> +    return getthrid();
>  #else
>      return getpid();
>  #endif
> @@ -408,6 +414,23 @@ void qemu_init_exec_dir(const char *argv0)
>              }
>          }
>      }
> +#elif defined(__OpenBSD__)
> +    {
> +
> +        char **args;
> +        size_t len;
> +        int mib[4] = {CTL_KERN, KERN_PROC_ARGS, getpid(), KERN_PROC_ARGV};
> +
> +        *buf = 0;
> +        if (!sysctl(mib, ARRAY_SIZE(mib), NULL, &len, NULL, 0)) {
> +            args = malloc(len);

If you want to use malloc() you need to check the return value.
But better to use g_malloc(), which can't return a failure value.

> +            if (!sysctl(mib, ARRAY_SIZE(mib), args, &len, NULL, 0)) {
> +                p = realpath(*args, buf);
> +            }
> +
> +            free(args);
> +        }
> +    }
>  #endif
>      /* If we don't have any way of figuring out the actual executable
>         location then try argv[0].  */
> --

thanks
-- PMM