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virpcimock: Mock __open_2()

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Hold on to your hat, this is going to be a wild ride. As nearly
nothing in glibc, nor open() is a real function. Just look into
bits/fcntl2.h and you'll see that open() is actually a thin
wrapper that calls either __open_alias() or __open_2(). Now,
before 801ebb5edb6 the open() done in
virPCIDeviceConfigOpenInternal() had a constant oflags (we were
opening the pci config with O_RDWR). And since we were not
passing any mode nor O_CREAT the wrapper decided to call
__open_alias() which was open() provided by our mock. So far so
good. But after the referenced commit, the oflags is no longer
compile time constant and therefore the wrapper calls __open_2()
which we don't mock and thus the real __open_2() from glibc was
called and thus we did try to open real path from host's /sys.
This of course fails with variety of errors.

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Erik Skultety <eskultet@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>
This commit is contained in:
Michal Privoznik 2019-08-15 16:37:17 +02:00
parent 301eb18bec
commit 459f071cac
1 changed files with 29 additions and 0 deletions
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29
tests/virpcimock.c
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@ -32,6 +32,7 @@
static int (*real_access)(const char *path, int mode);
static int (*real_open)(const char *path, int flags, ...);
static int (*real___open_2)(const char *path, int flags);
static int (*real_close)(int fd);
static DIR * (*real_opendir)(const char *name);
static char *(*real_virFileCanonicalizePath)(const char *path);
@ -805,6 +806,7 @@ init_syms(void)
VIR_MOCK_REAL_INIT(access);
VIR_MOCK_REAL_INIT(open);
VIR_MOCK_REAL_INIT(__open_2);
VIR_MOCK_REAL_INIT(close);
VIR_MOCK_REAL_INIT(opendir);
VIR_MOCK_REAL_INIT(virFileCanonicalizePath);
@ -932,6 +934,33 @@ open(const char *path, int flags, ...)
return ret;
}
int
__open_2(const char *path, int flags)
{
VIR_AUTOFREE(char *) newpath = NULL;
int ret;
init_syms();
if (STRPREFIX(path, SYSFS_PCI_PREFIX) &&
getrealpath(&newpath, path) < 0)
return -1;
ret = real___open_2(newpath ? newpath : path, flags);
/* Catch both: /sys/bus/pci/drivers/... and
* /sys/bus/pci/device/.../driver/... */
if (ret >= 0 && STRPREFIX(path, SYSFS_PCI_PREFIX) &&
strstr(path, "driver") && add_fd(ret, path) < 0) {
real_close(ret);
ret = -1;
}
return ret;
}
DIR *
opendir(const char *path)
{