kconfig: do not accept a directory for configuration output

Currently, conf_write() can be called with a directory name instead
of a file name. As far as I see, this can happen for menuconfig,
nconfig, gconfig.

If it is given with a directory path, conf_write() kindly appends
getenv("KCONFIG_CONFIG"), but this ends up with hacky dir/basename
handling, and screwed up in corner-cases like "what if KCONFIG_CONFIG
is an absolute path?" as discussed before:

  https://patchwork.kernel.org/patch/9910037/

Since conf_write() is already messed up, I'd say "do not do it".
Please pass a file path all the time. If a directory path is specified
for the configuration output, conf_write() will simply error out.

Now that the tmp file is created in the same directory as the .config,
the previously reported "what if KCONFIG_CONFIG points to a different
file system?" has been solved.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Nicolas Porcel <nicolasporcel06@gmail.com>
Signed-off-by: Christian Lamparter <chunkeey@gmail.com>

diff --git a/config/confdata.c b/config/confdata.c
index d67695d19ac77fdad52cbc4f4f005e8110ffcb58..da98566ccc6a45e68f1be3b03e7383831a7eb1a0 100644 (file)
--- a/config/confdata.c
+++ b/config/confdata.c
@@ -863,40 +863,31 @@ int conf_write(const char *name)
        FILE *out;
        struct symbol *sym;
        struct menu *menu;
-       const char *basename;
        const char *str;
-       char dirname[PATH_MAX+1], tmpname[PATH_MAX+22], newname[PATH_MAX+8];
+       char tmpname[PATH_MAX + 1], oldname[PATH_MAX + 1];
        char *env;
 
-       dirname[0] = 0;
-       if (name && name[0]) {
-               char *slash;
-
-               if (is_dir(name)) {
-                       strcpy(dirname, name);
-                       strcat(dirname, "/");
-                       basename = conf_get_configname();
-               } else if ((slash = strrchr(name, '/'))) {
-                       int size = slash - name + 1;
-                       memcpy(dirname, name, size);
-                       dirname[size] = 0;
-                       if (slash[1])
-                               basename = slash + 1;
-                       else
-                               basename = conf_get_configname();
-               } else
-                       basename = name;
-       } else
-               basename = conf_get_configname();
-
-       sprintf(newname, "%s%s", dirname, basename);
+       if (!name)
+               name = conf_get_configname();
+
+       if (!*name) {
+               fprintf(stderr, "config name is empty\n");
+               return -1;
+       }
+
+       if (is_dir(name)) {
+               fprintf(stderr, "%s: Is a directory\n", name);
+               return -1;
+       }
+
        env = getenv("KCONFIG_OVERWRITECONFIG");
-       if (!env || !*env) {
-               sprintf(tmpname, "%s.tmpconfig.%d", dirname, (int)getpid());
-               out = fopen(tmpname, "w");
-       } else {
+       if (env && *env) {
                *tmpname = 0;
-               out = fopen(newname, "w");
+               out = fopen(name, "w");
+       } else {
+               snprintf(tmpname, sizeof(tmpname), "%s.%d.tmp",
+                        name, (int)getpid());
+               out = fopen(tmpname, "w");
        }
        if (!out)
                return 1;
@@ -943,14 +934,13 @@ next:
        fclose(out);
 
        if (*tmpname) {
-               strcat(dirname, basename);
-               strcat(dirname, ".old");
-               rename(newname, dirname);
-               if (rename(tmpname, newname))
+               snprintf(oldname, sizeof(oldname), "%s.old", name);
+               rename(name, oldname);
+               if (rename(tmpname, name))
                        return 1;
        }
 
-       conf_message("configuration written to %s", newname);
+       conf_message("configuration written to %s", name);
 
        sym_set_change_count(0);