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libvirt/tests/virmockstathelpers.c
Michal Privoznik a091edf9db virmockstathelpers: Adapt to musl-1.2.4 
With musl-1.2.3: I get the following macros defined (from
$builddir/meson-config.h):

  #define WITH_LSTAT 1
  #define WITH_LSTAT64 1
  #define WITH_LSTAT_DECL 1
  #define WITH_STAT 1
  #define WITH_STAT64 1
  #define WITH_STAT_DECL 1
  #define WITH___LXSTAT 1
  #define WITH___LXSTAT64 1
  #define WITH___XSTAT 1
  #define WITH___XSTAT64 1

which in turn means the virmockstathelpers.c ends up defining:

  MOCK_STAT64
  MOCK_LSTAT64

But with  musl-1.2.4 everything changes and the set of defined
macros gets simplified to:

  #define WITH_LSTAT 1
  #define WITH_LSTAT_DECL 1
  #define WITH_STAT 1
  #define WITH_STAT_DECL 1
  #define WITH___LXSTAT 1
  #define WITH___XSTAT 1

which results in no MOCK_* macros defined in
virmockstathelpers.c, i.e. no stat() mocking, nada. The reason
for this simplification are these musl commits [1][2] which
removed all 64 bit aliases. And that's not what our logic for
deciding what flavor of stat() to mock counted with.

Nevertheless, we do build with Alpine Linux in our CI, so how
come we don't see this problem there? Well, simply because Alpine
Linux maintainers decided to revert the commits [3][4]. But on
distributions that use vanilla musl, this problem can be seen
easily.

1: https://git.musl-libc.org/cgit/musl/commit/?id=246f1c811448f37a44b41cd8df8d0ef9736d95f4
2: https://git.musl-libc.org/cgit/musl/commit/?id=25e6fee27f4a293728dd15b659170e7b9c7db9bc
3: https://git.alpinelinux.org/aports/commit/main/musl?id=6a5563fbb45b3d9d60678d7bbf60dbb312a2d481
4: https://git.alpinelinux.org/aports/commit/main/musl?id=a089bd852f8983623fa85e0f5755a3e25bf53c72

Resolves: https://bugs.gentoo.org/906167
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Martin Kletzander <mkletzan@redhat.com>
2023-05-16 08:48:17 +02:00

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/*
* Copyright (C) 2019 Red Hat, Inc.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library. If not, see
* <http://www.gnu.org/licenses/>.
*
* Helpers for dealing with the many variants of stat(). This
* C file should be included from any file that wants to mock
* stat() correctly.
*/
#include "virmock.h"
#include <sys/stat.h>
#include <unistd.h>
/*
* The POSIX stat() function might resolve to any number of different
* symbols in the C library.
*
* The may be an additional stat64() function exposed by the headers
* too.
*
* On 64-bit hosts the stat & stat64 functions are identical, always
* referring to the 64-bit ABI.
*
* On 32-bit hosts they refer to the 32-bit & 64-bit ABIs respectively.
*
* With meson libvirt will have _FILE_OFFSET_BITS=64 always defined.
* On 32-bit hosts it causes the C library to transparently rewrite
* stat() calls to be stat64() calls. Libvirt will never see the 32-bit
* ABI from the traditional stat() call. We cannot assume this rewriting
* is done using a macro. It might be, but on GLibC it is done with a
* magic __asm__ statement to apply the rewrite at link time instead of
* at preprocessing.
*
* In GLibC there may be two additional functions exposed by the headers,
* __xstat() and __xstat64(). When these exist, stat() and stat64() are
* transparently rewritten to call __xstat() and __xstat64() respectively.
* The former symbols will not actually exist in the library at all, only
* the header. The leading "__" indicates the symbols are a private impl
* detail of the C library that applications should not care about.
* Unfortunately, because we are trying to mock replace the C library,
* we need to know about this internal impl detail.
*
* Furthermore, support for 64-bit time can be enabled, which on 32-bit
* systems with glibc overwrites stat64() to __stat64_time64() and lstat64()
* to __lstat64_time64().
*
* On macOS stat() and lstat() are resolved to _stat$INODE64 and
* _lstat$INODE64, respectively. stat(2) man page also declares that
* stat64(), lstat64() and fstat64() are deprecated, and when
* building on Apple Silicon (aarch64) those functions are missing
* from the header altogether and should not be mocked.
*
* With all this in mind the list of functions we have to mock will depend
* on several factors
*
* - If the stat or __xstat but there is no 64-bit version.
*
* - If __xstat & __xstat64 exist, then stat & stat64 will not exist
* as symbols in the library, so the latter should not be mocked.
*
* - If __xstat exists in the library, but not the header than it
* it is just there for binary back compat and should not be
* mocked
*
* The same all applies to lstat()
*/
#if !defined(__APPLE__)
# if !defined(WITH___XSTAT_DECL)
# if defined(WITH_STAT)
# if !defined(WITH___XSTAT) && !defined(WITH_STAT64)
# define MOCK_STAT
# endif
# endif
# if defined(WITH_STAT64)
# define MOCK_STAT64
# endif
# else /* WITH___XSTAT_DECL */
# if defined(WITH___XSTAT) && !defined(WITH___XSTAT64)
# define MOCK___XSTAT
# endif
# if defined(WITH___XSTAT64)
# define MOCK___XSTAT64
# endif
# endif /* WITH___XSTAT_DECL */
# if !defined(WITH___LXSTAT_DECL)
# if defined(WITH_LSTAT)
# if !defined(WITH___LXSTAT) && !defined(WITH_LSTAT64)
# define MOCK_LSTAT
# endif
# endif
# if defined(WITH_LSTAT64)
# define MOCK_LSTAT64
# endif
# else /* WITH___LXSTAT_DECL */
# if defined(WITH___LXSTAT) && !defined(WITH___LXSTAT64)
# define MOCK___LXSTAT
# endif
# if defined(WITH___LXSTAT64)
# define MOCK___LXSTAT64
# endif
# endif /* WITH___LXSTAT_DECL */
#else /* __APPLE__ */
# define MOCK_STAT
# if defined(WITH_STAT64_DECL)
# define MOCK_STAT64
# endif
# define MOCK_LSTAT
# if defined(WITH_LSTAT64_DECL)
# define MOCK_LSTAT64
# endif
#endif
#if !defined(MOCK_STAT) && !defined(MOCK_STAT64) && \
!defined(MOCK___XSTAT) && !defined(MOCK___XSTAT64)
# define MOCK_STAT
#endif
#if !defined(MOCK_LSTAT) && !defined(MOCK_LSTAT64) && \
!defined(MOCK___LXSTAT) && !defined(MOCK___LXSTAT64)
# define MOCK_LSTAT
#endif
#ifdef MOCK_STAT
static int (*real_stat)(const char *path, struct stat *sb);
#endif
#ifdef MOCK_STAT64
static int (*real_stat64)(const char *path, struct stat64 *sb);
#endif
#ifdef MOCK___XSTAT
static int (*real___xstat)(int ver, const char *path, struct stat *sb);
#endif
#ifdef MOCK___XSTAT64
static int (*real___xstat64)(int ver, const char *path, struct stat64 *sb);
#endif
#ifdef MOCK_LSTAT
static int (*real_lstat)(const char *path, struct stat *sb);
#endif
#ifdef MOCK_LSTAT64
static int (*real_lstat64)(const char *path, struct stat64 *sb);
#endif
#ifdef MOCK___LXSTAT
static int (*real___lxstat)(int ver, const char *path, struct stat *sb);
#endif
#ifdef MOCK___LXSTAT64
static int (*real___lxstat64)(int ver, const char *path, struct stat64 *sb);
#endif
static bool init;
static bool debug;
#define fdebug(msg, ...) do { if (debug) fprintf(stderr, msg, __VA_ARGS__); } while (0)
static void virMockStatInit(void)
{
if (init)
return;
init = true;
debug = getenv("VIR_MOCK_STAT_DEBUG");
#ifdef MOCK_STAT
# if defined(__APPLE__) && defined(__x86_64__)
VIR_MOCK_REAL_INIT_ALIASED(stat, "stat$INODE64");
# else
VIR_MOCK_REAL_INIT(stat);
# endif
fdebug("real stat %p\n", real_stat);
#endif
#ifdef MOCK_STAT64
# if defined(__GLIBC__) && defined(_TIME_BITS) && _TIME_BITS == 64
VIR_MOCK_REAL_INIT_ALIASED(stat64, "__stat64_time64");
# else
VIR_MOCK_REAL_INIT(stat64);
# endif
fdebug("real stat64 %p\n", real_stat64);
#endif
#ifdef MOCK___XSTAT
VIR_MOCK_REAL_INIT(__xstat);
fdebug("real __xstat %p\n", real___xstat);
#endif
#ifdef MOCK___XSTAT64
VIR_MOCK_REAL_INIT(__xstat64);
fdebug("real __xstat64 %p\n", real___xstat64);
#endif
#ifdef MOCK_LSTAT
# if defined(__APPLE__) && defined(__x86_64__)
VIR_MOCK_REAL_INIT_ALIASED(lstat, "lstat$INODE64");
# else
VIR_MOCK_REAL_INIT(lstat);
# endif
fdebug("real lstat %p\n", real_lstat);
#endif
#ifdef MOCK_LSTAT64
# if defined(__GLIBC__) && defined(_TIME_BITS) && _TIME_BITS == 64
VIR_MOCK_REAL_INIT_ALIASED(lstat64, "__lstat64_time64");
# else
VIR_MOCK_REAL_INIT(lstat64);
# endif
fdebug("real lstat64 %p\n", real_lstat64);
#endif
#ifdef MOCK___LXSTAT
VIR_MOCK_REAL_INIT(__lxstat);
fdebug("real __lxstat %p\n", real___lxstat);
#endif
#ifdef MOCK___LXSTAT64
VIR_MOCK_REAL_INIT(__lxstat64);
fdebug("real __lxstat64 %p\n", real___lxstat64);
#endif
}
/*
* @stat: the path being queried
* @newpath: fill with redirected path, or leave NULL to use orig path
*
* Return 0 on success, -1 on allocation error
*/
static int virMockStatRedirect(const char *path, char **newpath);
#ifndef VIR_MOCK_STAT_HOOK
# define VIR_MOCK_STAT_HOOK do { } while (0)
#endif
#ifdef MOCK_STAT
int stat(const char *path, struct stat *sb)
{
g_autofree char *newpath = NULL;
virMockStatInit();
if (virMockStatRedirect(path, &newpath) < 0)
abort();
fdebug("stat redirect %s to %s sb=%p\n", path, newpath ? newpath : path, sb);
VIR_MOCK_STAT_HOOK;
return real_stat(newpath ? newpath : path, sb);
}
#endif
#ifdef MOCK_STAT64
int stat64(const char *path, struct stat64 *sb)
{
g_autofree char *newpath = NULL;
virMockStatInit();
if (virMockStatRedirect(path, &newpath) < 0)
abort();
fdebug("stat64 redirect %s to %s sb=%p\n", path, newpath ? newpath : path, sb);
VIR_MOCK_STAT_HOOK;
return real_stat64(newpath ? newpath : path, sb);
}
#endif
#ifdef MOCK___XSTAT
int
__xstat(int ver, const char *path, struct stat *sb)
{
g_autofree char *newpath = NULL;
virMockStatInit();
if (virMockStatRedirect(path, &newpath) < 0)
abort();
fdebug("__xstat redirect %s to %s sb=%p\n", path, newpath ? newpath : path, sb);
VIR_MOCK_STAT_HOOK;
return real___xstat(ver, newpath ? newpath : path, sb);
}
#endif
#ifdef MOCK___XSTAT64
int
__xstat64(int ver, const char *path, struct stat64 *sb)
{
g_autofree char *newpath = NULL;
virMockStatInit();
if (virMockStatRedirect(path, &newpath) < 0)
abort();
fdebug("__xstat64 redirect %s to %s sb=%p\n", path, newpath ? newpath : path, sb);
VIR_MOCK_STAT_HOOK;
return real___xstat64(ver, newpath ? newpath : path, sb);
}
#endif
#ifdef MOCK_LSTAT
int
lstat(const char *path, struct stat *sb)
{
g_autofree char *newpath = NULL;
virMockStatInit();
if (virMockStatRedirect(path, &newpath) < 0)
abort();
fdebug("lstat redirect %s to %s sb=%p\n", path, newpath ? newpath : path, sb);
VIR_MOCK_STAT_HOOK;
return real_lstat(newpath ? newpath : path, sb);
}
#endif
#ifdef MOCK_LSTAT64
int
lstat64(const char *path, struct stat64 *sb)
{
g_autofree char *newpath = NULL;
virMockStatInit();
if (virMockStatRedirect(path, &newpath) < 0)
abort();
fdebug("lstat64 redirect %s to %s sb=%p\n", path, newpath ? newpath : path, sb);
VIR_MOCK_STAT_HOOK;
return real_lstat64(newpath ? newpath : path, sb);
}
#endif
#ifdef MOCK___LXSTAT
int
__lxstat(int ver, const char *path, struct stat *sb)
{
g_autofree char *newpath = NULL;
virMockStatInit();
if (virMockStatRedirect(path, &newpath) < 0)
abort();
fdebug("__lxstat redirect %s to %s sb=%p\n", path, newpath ? newpath : path, sb);
VIR_MOCK_STAT_HOOK;
return real___lxstat(ver, newpath ? newpath : path, sb);
}
#endif
#ifdef MOCK___LXSTAT64
int
__lxstat64(int ver, const char *path, struct stat64 *sb)
{
g_autofree char *newpath = NULL;
virMockStatInit();
if (virMockStatRedirect(path, &newpath) < 0)
abort();
fdebug("__lxstat64 redirect %s to %s sb=%p\n", path, newpath ? newpath : path, sb);
VIR_MOCK_STAT_HOOK;
return real___lxstat64(ver, newpath ? newpath : path, sb);
}
#endif
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