Re: [libvirt] main: fix some compilation issues on non-linux platforms
On 08/16/2011 02:34 PM, Stefan Berger wrote:
On 08/16/2011 02:14 PM, Eric Blake wrote:
> On 08/16/2011 12:07 PM, Stefan Berger wrote:
>> I split this off and pushed the rest.
>> If procfs's are different, then maybe we should use #if
>> PROCFS_PID_EXE_LINK_AVAIL here.
>
> Seems like a reasonable name.
>
>> What is needed in this case seems to be that /proc/<pid>/exe is a
>> symbolic link to the executable. This works in Linux and cygwin. Would
>> testing via
>>
>> stat /proc/<pid>/exe | sed -n 's/.*\(symbolic link\).*/\1/p'
>>
>> be a valid test for this that works on all targeted platforms?
>
> stat(1) is not universal, and while it is on both Linux and Cygwin,
> it might not be present on some other platform that has a procfs that
> does what we want. It may be sufficient to just use 'test -h
> /proc/pid/exe' to see if there is a symlink.
>
> Also, you'd need to wrap the test in a cache variable (to allow
> overrides if we guessed wrong), as well as to skip the test (and
> assume the worst or at least make some default guesses based on known
> $host_os) when cross-compiling, since the existence of procfs on the
> host machine says nothing about it being on the target machine.
>
Following the latter couldn't it just be handled during runtime
altogether?
Stefan
Along those lines I propose this patch below:
Signed-off-by: Stefan Berger <stefanb(a)linux.vnet.ibm.com>
---
src/libvirt_private.syms | 1 +
src/util/util.c | 17 +++++++++++++++++
src/util/util.h | 2 ++
src/util/virpidfile.c | 7 ++++---
4 files changed, 24 insertions(+), 3 deletions(-)
Index: libvirt-acl/src/util/virpidfile.c
===================================================================
--- libvirt-acl.orig/src/util/virpidfile.c
+++ libvirt-acl/src/util/virpidfile.c
@@ -210,10 +210,11 @@ int virPidFileReadPathIfAlive(const char
*pid = -1;
return 0;
}
-#ifdef __linux__
- if (virFileLinkPointsTo(procpath, binpath) == 0)
+
+ if (virFileIsLink(procpath) &&
+ virFileLinkPointsTo(procpath, binpath) == 0)
*pid = -1;
-#endif
+
VIR_FREE(procpath);
return 0;
Index: libvirt-acl/src/util/util.c
===================================================================
--- libvirt-acl.orig/src/util/util.c
+++ libvirt-acl/src/util/util.c
@@ -570,6 +570,23 @@ int virFileResolveLink(const char *linkp
return *resultpath == NULL ? -1 : 0;
}
+
+/*
+ * Check whether the given file is a link.
+ * Returns 1 in case of the file being a link, 0 in case it is not
+ * a link and the negative errno in all other cases.
+ */
+int virFileIsLink(const char *linkpath)
+{
+ struct stat st;
+
+ if (lstat(linkpath, &st) < 0)
+ return -errno;
+
+ return S_ISLNK(st.st_mode);
+}
+
+
/*
* Finds a requested executable file in the PATH env. e.g.:
* "kvm-img" will return "/usr/bin/kvm-img"
Index: libvirt-acl/src/util/util.h
===================================================================
--- libvirt-acl.orig/src/util/util.h
+++ libvirt-acl/src/util/util.h
@@ -78,6 +78,8 @@ int virFileLinkPointsTo(const char *chec
int virFileResolveLink(const char *linkpath,
char **resultpath) ATTRIBUTE_RETURN_CHECK;
+int virFileIsLink(const char *linkpath) ATTRIBUTE_RETURN_CHECK;
+
char *virFindFileInPath(const char *file);
bool virFileExists(const char *file) ATTRIBUTE_NONNULL(1);
Index: libvirt-acl/src/libvirt_private.syms
===================================================================
--- libvirt-acl.orig/src/libvirt_private.syms
+++ libvirt-acl/src/libvirt_private.syms
@@ -1047,6 +1047,7 @@ virFileExists;
virFileFindMountPoint;
virFileHasSuffix;
virFileIsExecutable;
+virFileIsLink;
virFileLinkPointsTo;
virFileLock;
virFileMakePath;