qemu_get_runtime_dir() returns a dynamically allocated directory path that is appropriate for storing runtime files. It corresponds to "run" directory in Unix.
With a tree-wide search, it was found that there are several cases where such a functionality is implemented so let's have one as a common utlity function. A notable feature of qemu_get_runtime_dir() is that it uses $XDG_RUNTIME_DIR if available. While the function is often called by executables which requires root privileges, it is still possible that they are called from a user without privilege to write the system runtime directory. In fact, I decided to write this patch when I ran virtiofsd in a Linux namespace created by a normal user and realized it tries to write the system runtime directory, not writable in this case. $XDG_RUNTIME_DIR should provide a writable directory in such cases. This function does not use qemu_get_local_state_dir() or its logic for Windows. Actually the implementation of qemu_get_local_state_dir() for Windows seems not right as it calls g_get_system_data_dirs(), which refers to $XDG_DATA_DIRS. In Unix terminology, it is basically "/usr/share", not "/var", which qemu_get_local_state_dir() is intended to provide. Instead, this function try to use the following in order: - $XDG_RUNTIME_DIR - LocalAppData folder - get_relocated_path(CONFIG_QEMU_LOCALSTATEDIR "/run") This function does not use g_get_user_runtime_dir() either as it falls back to g_get_user_cache_dir() when $XDG_DATA_DIRS is not available. In the case, we rather use: get_relocated_path(CONFIG_QEMU_LOCALSTATEDIR "/run") Signed-off-by: Akihiko Odaki <akihiko.od...@daynix.com> --- include/qemu/osdep.h | 12 ++++++++++++ util/oslib-posix.c | 11 +++++++++++ util/oslib-win32.c | 26 ++++++++++++++++++++++++++ 3 files changed, 49 insertions(+) diff --git a/include/qemu/osdep.h b/include/qemu/osdep.h index b9c4307779..86445aad25 100644 --- a/include/qemu/osdep.h +++ b/include/qemu/osdep.h @@ -565,6 +565,18 @@ void qemu_set_cloexec(int fd); */ char *qemu_get_local_state_dir(void); +/** + * qemu_get_runtime_dir: + * + * Return a dynamically allocated directory path that is appropriate for storing + * runtime files. It corresponds to "run" directory in Unix, and uses + * $XDG_RUNTIME_DIR if available. + * + * The caller is responsible for releasing the value returned with g_free() + * after use. + */ +char *qemu_get_runtime_dir(void); + /** * qemu_getauxval: * @type: the auxiliary vector key to lookup diff --git a/util/oslib-posix.c b/util/oslib-posix.c index 59a891b6a8..9a0b3913ff 100644 --- a/util/oslib-posix.c +++ b/util/oslib-posix.c @@ -279,6 +279,17 @@ qemu_get_local_state_dir(void) return get_relocated_path(CONFIG_QEMU_LOCALSTATEDIR); } +char * +qemu_get_runtime_dir(void) +{ + char *env = getenv("XDG_RUNTIME_DIR"); + if (env) { + return g_strdup(env); + } + + return get_relocated_path(CONFIG_QEMU_LOCALSTATEDIR "/run"); +} + void qemu_set_tty_echo(int fd, bool echo) { struct termios tty; diff --git a/util/oslib-win32.c b/util/oslib-win32.c index a67cb3822e..6ad1bb4bac 100644 --- a/util/oslib-win32.c +++ b/util/oslib-win32.c @@ -31,6 +31,8 @@ */ #include "qemu/osdep.h" +#include <shlobj.h> +#include <wchar.h> #include <windows.h> #include "qapi/error.h" #include "qemu/main-loop.h" @@ -241,6 +243,30 @@ qemu_get_local_state_dir(void) return g_strdup(data_dirs[0]); } +char * +qemu_get_runtime_dir(void) +{ + size_t size = GetEnvironmentVariableA("XDG_RUNTIME_DIR", NULL, 0); + if (size) { + char *env = g_malloc(size); + GetEnvironmentVariableA("XDG_RUNTIME_DIR", env, size); + return env; + } + + PWSTR wpath; + const wchar_t *cwpath; + if (!SHGetKnownFolderPath(&FOLDERID_LocalAppData, KF_FLAG_DEFAULT, NULL, &wpath)) { + cwpath = wpath; + size = wcsrtombs(NULL, &cwpath, 0, &(mbstate_t){0}) + 1; + char *path = g_malloc(size); + wcsrtombs(path, &cwpath, size, &(mbstate_t){0}); + CoTaskMemFree(wpath); + return path; + } + + return get_relocated_path(CONFIG_QEMU_LOCALSTATEDIR "/run"); +} + void qemu_set_tty_echo(int fd, bool echo) { HANDLE handle = (HANDLE)_get_osfhandle(fd); -- 2.38.1