which: fix TODO with NOFORK+malloc_failure misbehaving

function                                             old     new   delta
find_executable                                       86     104     +18
which_main                                           202     194      -8
executable_exists                                     66      51     -15
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 1/2 up/down: 18/-23)             Total: -5 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

diff --git a/debianutils/which.c b/debianutils/which.c
index 3bd54ac422974339ac420e2d01c5be3a0574eee0..02f77a216ae675051a6a4872b8cbb3334bad98ac 100644 (file)
--- a/debianutils/which.c
+++ b/debianutils/which.c
@@ -30,12 +30,15 @@
 int which_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 int which_main(int argc UNUSED_PARAM, char **argv)
 {
-       const char *env_path;
+       char *env_path;
        int status = 0;
+       /* This sizeof(): bb_default_root_path is shorter than BB_PATH_ROOT_PATH */
+       char buf[sizeof(BB_PATH_ROOT_PATH)];
 
        env_path = getenv("PATH");
        if (!env_path)
-               env_path = bb_default_root_path;
+               /* env_path must be writable, and must not alloc, so... */
+               env_path = strcpy(buf, bb_default_root_path);
 
        getopt32(argv, "^" "a" "\0" "-1"/*at least one arg*/);
        argv += optind;
@@ -51,20 +54,17 @@ int which_main(int argc UNUSED_PARAM, char **argv)
                        }
                } else {
                        char *path;
-                       char *tmp;
                        char *p;
 
-                       path = tmp = xstrdup(env_path);
-//NOFORK FIXME: nested xmallocs (one is inside find_executable())
-//can leak memory on failure
-                       while ((p = find_executable(*argv, &tmp)) != NULL) {
+                       path = env_path;
+                       /* NOFORK NB: xmalloc inside find_executable(), must have no allocs above! */
+                       while ((p = find_executable(*argv, &path)) != NULL) {
                                missing = 0;
                                puts(p);
                                free(p);
                                if (!option_mask32) /* -a not set */
                                        break;
                        }
-                       free(path);
                }
                status |= missing;
        } while (*++argv);

diff --git a/include/libbb.h b/include/libbb.h
index daccf154a339a005210f4a3bec8ff7b0ba3af1a0..5f25b5ddeb02222e68636514bd7ef55a650a514d 100644 (file)
--- a/include/libbb.h
+++ b/include/libbb.h
@@ -2005,10 +2005,16 @@ extern const char bb_path_wtmp_file[] ALIGN1;
 
 #define bb_dev_null "/dev/null"
 extern const char bb_busybox_exec_path[] ALIGN1;
-/* util-linux manpage says /sbin:/bin:/usr/sbin:/usr/bin,
- * but I want to save a few bytes here */
-extern const char bb_PATH_root_path[] ALIGN1; /* "PATH=/sbin:/usr/sbin:/bin:/usr/bin" */
+/* allow default system PATH to be extended via CFLAGS */
+#ifndef BB_ADDITIONAL_PATH
+#define BB_ADDITIONAL_PATH ""
+#endif
+#define BB_PATH_ROOT_PATH "PATH=/sbin:/usr/sbin:/bin:/usr/bin" BB_ADDITIONAL_PATH
+extern const char bb_PATH_root_path[] ALIGN1; /* BB_PATH_ROOT_PATH */
 #define bb_default_root_path (bb_PATH_root_path + sizeof("PATH"))
+/* util-linux manpage says /sbin:/bin:/usr/sbin:/usr/bin,
+ * but I want to save a few bytes here:
+ */
 #define bb_default_path      (bb_PATH_root_path + sizeof("PATH=/sbin:/usr/sbin"))
 
 extern const int const_int_0;

diff --git a/libbb/executable.c b/libbb/executable.c
index 325dd0107b89745fce644928ff91f74084f347a7..29d2a2c8547163a59e9ac75bb338a00996aa26ca 100644 (file)
--- a/libbb/executable.c
+++ b/libbb/executable.c
@@ -25,7 +25,8 @@ int FAST_FUNC file_is_executable(const char *name)
  *  you may call find_executable again with this PATHp to continue
  *  (if it's not NULL).
  * return NULL otherwise; (PATHp is undefined)
- * in all cases (*PATHp) contents will be trashed (s/:/NUL/).
+ * in all cases (*PATHp) contents are temporarily modified
+ * but are restored on return (s/:/NUL/ and back).
  */
 char* FAST_FUNC find_executable(const char *filename, char **PATHp)
 {
@@ -41,14 +42,17 @@ char* FAST_FUNC find_executable(const char *filename, char **PATHp)
 
        p = *PATHp;
        while (p) {
+               int ex;
+
                n = strchr(p, ':');
-               if (n)
-                       *n++ = '\0';
+               if (n) *n = '\0';
                p = concat_path_file(
                        p[0] ? p : ".", /* handle "::" case */
                        filename
                );
-               if (file_is_executable(p)) {
+               ex = file_is_executable(p);
+               if (n) *n++ = ':';
+               if (ex) {
                        *PATHp = n;
                        return p;
                }
@@ -64,10 +68,8 @@ char* FAST_FUNC find_executable(const char *filename, char **PATHp)
  */
 int FAST_FUNC executable_exists(const char *filename)
 {
-       char *path = xstrdup(getenv("PATH"));
-       char *tmp = path;
-       char *ret = find_executable(filename, &tmp);
-       free(path);
+       char *path = getenv("PATH");
+       char *ret = find_executable(filename, &path);
        free(ret);
        return ret != NULL;
 }

diff --git a/libbb/messages.c b/libbb/messages.c
index 0a6cf3bf8c61ef663f50d82df4de7df997e5cc20..6914d570186e81bb6fb2614f720d27dc65e3f364 100644 (file)
--- a/libbb/messages.c
+++ b/libbb/messages.c
@@ -6,11 +6,6 @@
  */
 #include "libbb.h"
 
-/* allow default system PATH to be extended via CFLAGS */
-#ifndef BB_ADDITIONAL_PATH
-#define BB_ADDITIONAL_PATH ""
-#endif
-
 /* allow version to be extended, via CFLAGS */
 #ifndef BB_EXTRA_VERSION
 #define BB_EXTRA_VERSION " ("AUTOCONF_TIMESTAMP")"
@@ -36,8 +31,7 @@ const char bb_busybox_exec_path[] ALIGN1 = CONFIG_BUSYBOX_EXEC_PATH;
 const char bb_default_login_shell[] ALIGN1 = LIBBB_DEFAULT_LOGIN_SHELL;
 /* util-linux manpage says /sbin:/bin:/usr/sbin:/usr/bin,
  * but I want to save a few bytes here. Check libbb.h before changing! */
-const char bb_PATH_root_path[] ALIGN1 =
-       "PATH=/sbin:/usr/sbin:/bin:/usr/bin" BB_ADDITIONAL_PATH;
+const char bb_PATH_root_path[] ALIGN1 = BB_PATH_ROOT_PATH;
 
 
 //const int const_int_1 = 1;