Re: [PATCH 02/13] oslib: do not call g_strdup from qemu_get_exec_dir

[Thomas Huth]

On 01/09/2020 08.20, Paolo Bonzini wrote:
> Just return the directory without requiring the caller to free it.
> This also removes a bogus check for NULL in os_find_datadir and
> module_load_one; g_strdup of a static variable cannot return NULL.
> 
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
>  include/qemu/osdep.h    |  8 ++------
>  os-posix.c              |  6 +-----
>  os-win32.c              |  2 +-
>  tests/qtest/fuzz/fuzz.c |  4 ++--
>  util/module.c           |  7 +------
>  util/oslib-posix.c      |  8 +++++---
>  util/oslib-win32.c      | 12 ++++++++----
>  7 files changed, 20 insertions(+), 27 deletions(-)
> 
> diff --git a/include/qemu/osdep.h b/include/qemu/osdep.h
> index 412962d91a..db2cfffaff 100644
> --- a/include/qemu/osdep.h
> +++ b/include/qemu/osdep.h
> @@ -590,12 +590,8 @@ char *qemu_get_local_state_pathname(const char 
> *relative_pathname);
>   * Try OS specific API first, if not working, parse from argv0. */
>  void qemu_init_exec_dir(const char *argv0);
>  
> -/* Get the saved exec dir.
> - *
> - * The caller is responsible for releasing the value returned with g_free()
> - * after use.
> - */
> -char *qemu_get_exec_dir(void);
> +/* Get the saved exec dir.  */
> +const char *qemu_get_exec_dir(void);
>  
>  /**
>   * qemu_getauxval:
> diff --git a/os-posix.c b/os-posix.c
> index bf98508b6d..8d8e7fc15c 100644
> --- a/os-posix.c
> +++ b/os-posix.c
> @@ -90,13 +90,9 @@ void os_setup_signal_handling(void)
>   */
>  char *os_find_datadir(void)
>  {
> -    g_autofree char *exec_dir = NULL;
>      g_autofree char *dir = NULL;
>  
> -    exec_dir = qemu_get_exec_dir();
> -    g_return_val_if_fail(exec_dir != NULL, NULL);
> -
> -    dir = g_build_filename(exec_dir, "pc-bios", NULL);
> +    dir = g_build_filename(qemu_get_exec_dir(), "pc-bios", NULL);
>      if (g_file_test(dir, G_FILE_TEST_IS_DIR)) {
>          return g_steal_pointer(&dir);
>      }
> diff --git a/os-win32.c b/os-win32.c
> index c9c3afe648..eb8501b9e5 100644
> --- a/os-win32.c
> +++ b/os-win32.c
> @@ -65,7 +65,7 @@ void os_setup_early_signal_handling(void)
>   */
>  char *os_find_datadir(void)
>  {
> -    return qemu_get_exec_dir();
> +    return g_strdup(qemu_get_exec_dir());
>  }
>  
>  void os_set_line_buffering(void)
> diff --git a/tests/qtest/fuzz/fuzz.c b/tests/qtest/fuzz/fuzz.c
> index 391223219d..1811cb1d88 100644
> --- a/tests/qtest/fuzz/fuzz.c
> +++ b/tests/qtest/fuzz/fuzz.c
> @@ -143,7 +143,8 @@ int LLVMFuzzerInitialize(int *argc, char ***argv, char 
> ***envp)
>  {
>  
>      char *target_name;
> -    char *bindir, *datadir;
> +    const char *bindir;
> +    char *datadir;
>      bool serialize = false;
>  
>      /* Initialize qgraph and modules */
> @@ -167,7 +168,6 @@ int LLVMFuzzerInitialize(int *argc, char ***argv, char 
> ***envp)
>           */
>          bindir = qemu_get_exec_dir();
>          datadir = g_build_filename(bindir, "pc-bios", NULL);
> -        g_free(bindir);
>          if (g_file_test(datadir, G_FILE_TEST_IS_DIR)) {
>              qemu_add_data_dir(datadir);
>          }
> diff --git a/util/module.c b/util/module.c
> index 6e63006a8f..aed04b578a 100644
> --- a/util/module.c
> +++ b/util/module.c
> @@ -172,7 +172,6 @@ bool module_load_one(const char *prefix, const char 
> *lib_name)
>  
>  #ifdef CONFIG_MODULES
>      char *fname = NULL;
> -    char *exec_dir;
>  #ifdef CONFIG_MODULE_UPGRADES
>      char *version_dir;
>  #endif
> @@ -199,13 +198,12 @@ bool module_load_one(const char *prefix, const char 
> *lib_name)
>          return true;
>      }
>  
> -    exec_dir = qemu_get_exec_dir();
>      search_dir = getenv("QEMU_MODULE_DIR");
>      if (search_dir != NULL) {
>          dirs[n_dirs++] = g_strdup_printf("%s", search_dir);
>      }
>      dirs[n_dirs++] = g_strdup_printf("%s", CONFIG_QEMU_MODDIR);
> -    dirs[n_dirs++] = g_strdup_printf("%s", exec_dir ? : "");
> +    dirs[n_dirs++] = g_strdup(qemu_get_exec_dir());
>  
>  #ifdef CONFIG_MODULE_UPGRADES
>      version_dir = g_strcanon(g_strdup(QEMU_PKGVERSION),
> @@ -216,9 +214,6 @@ bool module_load_one(const char *prefix, const char 
> *lib_name)
>  
>      assert(n_dirs <= ARRAY_SIZE(dirs));
>  
> -    g_free(exec_dir);
> -    exec_dir = NULL;
> -
>      for (i = 0; i < n_dirs; i++) {
>          fname = g_strdup_printf("%s/%s%s",
>                  dirs[i], module_name, CONFIG_HOST_DSOSUF);
> diff --git a/util/oslib-posix.c b/util/oslib-posix.c
> index ad8001a4ad..0dd8d24076 100644
> --- a/util/oslib-posix.c
> +++ b/util/oslib-posix.c
> @@ -366,7 +366,9 @@ void qemu_init_exec_dir(const char *argv0)
>      char *p = NULL;
>      char buf[PATH_MAX];
>  
> -    assert(!exec_dir[0]);
> +    if (exec_dir[0]) {
> +        return;
> +    }
>  
>  #if defined(__linux__)
>      {
> @@ -439,9 +441,9 @@ void qemu_init_exec_dir(const char *argv0)
>      g_free(dir);
>  }
>  
> -char *qemu_get_exec_dir(void)
> +const char *qemu_get_exec_dir(void)
>  {
> -    return g_strdup(exec_dir);
> +    return exec_dir;
>  }
>  
>  static void sigbus_handler(int signal)
> diff --git a/util/oslib-win32.c b/util/oslib-win32.c
> index c654dafd93..1a33912944 100644
> --- a/util/oslib-win32.c
> +++ b/util/oslib-win32.c
> @@ -315,7 +315,7 @@ void qemu_set_tty_echo(int fd, bool echo)
>      }
>  }
>  
> -static char exec_dir[PATH_MAX];
> +static char *exec_dir;
>  
>  void qemu_init_exec_dir(const char *argv0)
>  {
> @@ -324,6 +324,10 @@ void qemu_init_exec_dir(const char *argv0)
>      char buf[MAX_PATH];
>      DWORD len;
>  
> +    if (exec_dir) {
> +        return;
> +    }
> +
>      len = GetModuleFileName(NULL, buf, sizeof(buf) - 1);
>      if (len == 0) {
>          return;
> @@ -336,13 +340,13 @@ void qemu_init_exec_dir(const char *argv0)
>      }
>      *p = 0;
>      if (access(buf, R_OK) == 0) {
> -        pstrcpy(exec_dir, sizeof(exec_dir), buf);
> +        exec_dir = g_strdup(buf);
>      }
>  }
>  
> -char *qemu_get_exec_dir(void)
> +const char *qemu_get_exec_dir(void)
>  {
> -    return g_strdup(exec_dir);
> +    return exec_dir;
>  }
>  
>  #if !GLIB_CHECK_VERSION(2, 50, 0)
> 

Reviewed-by: Thomas Huth <thuth@redhat.com>