hush: implement "command -v -V"

function                                             old     new   delta
pseudo_exec_argv                                     231     374    +143
if_command_vV_print_and_exit                           -     127    +127
builtin_set                                          267     273      +6
------------------------------------------------------------------------------
(add/remove: 1/0 grow/shrink: 2/0 up/down: 276/0)             Total: 276 bytes

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

1 files changed, 84 insertions, 31 deletions

diff --git a/shell/hush.c b/shell/hush.c
index 93779ba1e..196bdbe97 100644
--- a/shell/hush.c
+++ b/shell/hush.c
@@ -47,18 +47,13 @@
  *      follow IFS rules more precisely, including update semantics
  *      tilde expansion
  *      aliases
- *      builtins mandated by standards we don't support:
- *          [un]alias, command, fc:
- *          command -v CMD: print "/path/to/CMD"
- *              prints "CMD" for builtins
- *              prints "alias ALIAS='EXPANSION'" for aliases
- *              prints nothing and sets $? to 1 if not found
- *          command -V CMD: print "CMD is /path/CMD|a shell builtin|etc"
- *          command [-p] CMD: run CMD, even if a function CMD also exists
- *              (can use this to override standalone shell as well)
- *              -p: use default $PATH
+ *      "command" missing features:
+ *          command -p CMD: run CMD using default $PATH
+ *              (can use this to override standalone shell as well?)
  *          command BLTIN: disables special-ness (e.g. errors do not abort)
- *          NB: so far, only naked "command CMD" is implemented.
+ *          command -V CMD1 CMD2 CMD3 (multiple args) (not in standard)
+ *      builtins mandated by standards we don't support:
+ *          [un]alias, fc:
  *          fc -l[nr] [BEG] [END]: list range of commands in history
  *          fc [-e EDITOR] [BEG] [END]: edit/rerun range of commands
  *          fc -s [PAT=REP] [CMD]: rerun CMD, replacing PAT with REP
@@ -7337,6 +7332,30 @@ static void dump_cmd_in_x_mode(char **argv)
 # define dump_cmd_in_x_mode(argv) ((void)0)
 #endif
 
+#if ENABLE_HUSH_COMMAND
+static void if_command_vV_print_and_exit(char opt_vV, char *cmd, const char *explanation)
+{
+        char *to_free;
+        if (!opt_vV)
+                return;
+
+        to_free = NULL;
+        if (!explanation) {
+                char *path = getenv("PATH");
+                explanation = to_free = find_executable(cmd, &path); /* path == NULL is ok */
+                if (opt_vV != 'V')
+                        cmd = to_free; /* -v PROG prints "/path/to/PROG" */
+        }
+        if (explanation)
+                printf((opt_vV == 'V') ? "%s is %s\n" : "%s\n", cmd, explanation);
+        free(to_free);
+        fflush_all();
+        _exit(explanation == NULL); /* exit 1 if PROG was not found */
+}
+#else
+# define if_command_vV_print_and_exit(a,b,c) ((void)0)
+#endif
+
 #if BB_MMU
 #define pseudo_exec_argv(nommu_save, argv, assignment_cnt, argv_expanded) \
         pseudo_exec_argv(argv, assignment_cnt, argv_expanded)
@@ -7357,7 +7376,11 @@ static NOINLINE void pseudo_exec_argv(nommu_save_t *nommu_save,
                 char **argv, int assignment_cnt,
                 char **argv_expanded)
 {
+        const struct built_in_command *x;
         char **new_env;
+#if ENABLE_HUSH_COMMAND
+        char opt_vV = 0;
+#endif
 
         new_env = expand_assignments(argv, assignment_cnt);
         dump_cmd_in_x_mode(new_env);
@@ -7406,30 +7429,58 @@ static NOINLINE void pseudo_exec_argv(nommu_save_t *nommu_save,
         }
 #endif
 
+#if ENABLE_HUSH_COMMAND
+        /* "command BAR": run BAR without looking it up among functions
+         * "command -v BAR": print "BAR" or "/path/to/BAR"; or exit 1
+         * "command -V BAR": print "BAR is {a function,a shell builtin,/path/to/BAR}"
+         */
+        while (strcmp(argv[0], "command") == 0 && argv[1]) {
+                char *p;
+
+                argv++;
+                p = *argv;
+                if (p[0] != '-' || !p[1])
+                        continue; /* bash allows "command command command [-OPT] BAR" */
+
+                for (;;) {
+                        p++;
+                        switch (*p) {
+                        case '\0':
+                                argv++;
+                                p = *argv;
+                                if (p[0] != '-' || !p[1])
+                                        goto after_opts;
+                                continue; /* next arg is also -opts, process it too */
+                        case 'v':
+                        case 'V':
+                                opt_vV = *p;
+                                continue;
+                        default:
+                                bb_error_msg_and_die("%s: %s: invalid option", "command", argv[0]);
+                        }
+                }
+        }
+ after_opts:
+# if ENABLE_HUSH_FUNCTIONS
+        if (opt_vV && find_function(argv[0]))
+                if_command_vV_print_and_exit(opt_vV, argv[0], "a function");
+# endif
+#endif
+
         /* Check if the command matches any of the builtins.
          * Depending on context, this might be redundant.  But it's
          * easier to waste a few CPU cycles than it is to figure out
          * if this is one of those cases.
          */
-        {
-                const struct built_in_command *x;
-
-#if ENABLE_HUSH_COMMAND
-                /* This loop effectively makes "command BAR" run BAR without
-                 * looking it up among functions.
-                 */
-                while (strcmp(argv[0], "command") == 0 && argv[1])
-                        argv++;
-//TODO: implement -Vvp and "disable dying if BAR is a builtin" behavior
-#endif
-                /* On NOMMU, it is more expensive to re-execute shell
-                 * just in order to run echo or test builtin.
-                 * It's better to skip it here and run corresponding
-                 * non-builtin later. */
-                x = BB_MMU ? find_builtin(argv[0]) : find_builtin1(argv[0]);
-                if (x) {
-                        exec_builtin(&nommu_save->argv_from_re_execing, x, argv);
-                }
+        /* Why "BB_MMU ? :" difference in logic? -
+         * On NOMMU, it is more expensive to re-execute shell
+         * just in order to run echo or test builtin.
+         * It's better to skip it here and run corresponding
+         * non-builtin later. */
+        x = BB_MMU ? find_builtin(argv[0]) : find_builtin1(argv[0]);
+        if (x) {
+                if_command_vV_print_and_exit(opt_vV, argv[0], "a shell builtin");
+                exec_builtin(&nommu_save->argv_from_re_execing, x, argv);
         }
 
 #if ENABLE_FEATURE_SH_STANDALONE
@@ -7437,6 +7488,7 @@ static NOINLINE void pseudo_exec_argv(nommu_save_t *nommu_save,
         {
                 int a = find_applet_by_name(argv[0]);
                 if (a >= 0) {
+                        if_command_vV_print_and_exit(opt_vV, argv[0], "an applet");
 # if BB_MMU /* see above why on NOMMU it is not allowed */
                         if (APPLET_IS_NOEXEC(a)) {
                                 /* Do not leak open fds from opened script files etc.
@@ -7466,6 +7518,7 @@ static NOINLINE void pseudo_exec_argv(nommu_save_t *nommu_save,
 #if ENABLE_FEATURE_SH_STANDALONE || BB_MMU
  skip:
 #endif
+        if_command_vV_print_and_exit(opt_vV, argv[0], NULL);
         execvp_or_die(argv);
 }
 
@@ -9895,7 +9948,7 @@ static int FAST_FUNC builtin_set(char **argv)
 
         /* Nothing known, so abort */
  error:
-        bb_error_msg("set: %s: invalid option", arg);
+        bb_error_msg("%s: %s: invalid option", "set", arg);
         return EXIT_FAILURE;
 }
 #endif