hush: implement `type`

Implement support for the POSIX `type` command.  Only POSIX stuff is
supported here, no bash extensions like -p or -P.

In the process, split the $PATH searching code out of builtin_source() and
into its own find_in_path() function so we don't duplicate it.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>

1 files changed, 78 insertions, 27 deletions

diff --git a/shell/hush.c b/shell/hush.c
index 7167de701..efa93c1a6 100644
--- a/shell/hush.c
+++ b/shell/hush.c
@@ -539,6 +539,7 @@ static int builtin_shift(char **argv);
 static int builtin_source(char **argv);
 static int builtin_test(char **argv);
 static int builtin_trap(char **argv);
+static int builtin_type(char **argv);
 static int builtin_true(char **argv);
 static int builtin_umask(char **argv);
 static int builtin_unset(char **argv);
@@ -610,6 +611,7 @@ static const struct built_in_command bltins[] = {
         BLTIN("shift"   , builtin_shift   , "Shift positional parameters"),
         BLTIN("test"    , builtin_test    , "Test condition"),
         BLTIN("trap"    , builtin_trap    , "Trap signals"),
+        BLTIN("type"    , builtin_type    , "Write a description of command type"),
 //      BLTIN("ulimit"  , builtin_return  , "Control resource limits"),
         BLTIN("umask"   , builtin_umask   , "Set file creation mask"),
         BLTIN("unset"   , builtin_unset   , "Unset environment variable"),
@@ -2865,6 +2867,39 @@ static struct pipe *parse_stream(char **pstring,
 static void parse_and_run_string(const char *s);
 
 
+static char *find_in_path(const char *arg)
+{
+        char *ret = NULL;
+        const char *PATH = get_local_var_value("PATH");
+
+        if (!PATH)
+                return NULL;
+
+        while (1) {
+                const char *end = strchrnul(PATH, ':');
+                int sz = end - PATH; /* must be int! */
+
+                free(ret);
+                if (sz != 0) {
+                        ret = xasprintf("%.*s/%s", sz, PATH, arg);
+                } else {
+                        /* We have xxx::yyyy in $PATH,
+                         * it means "use current dir" */
+                        ret = xstrdup(arg);
+                }
+                if (access(ret, F_OK) == 0)
+                        break;
+
+                if (*end == '\0') {
+                        free(ret);
+                        return NULL;
+                }
+                PATH = end + 1;
+        }
+
+        return ret;
+}
+
 static const struct built_in_command* find_builtin(const char *name)
 {
         const struct built_in_command *x;
@@ -6728,6 +6763,43 @@ static int builtin_trap(char **argv)
         goto process_sig_list;
 }
 
+/* http://www.opengroup.org/onlinepubs/9699919799/utilities/type.html */
+static int builtin_type(char **argv)
+{
+        int i, ret = EXIT_SUCCESS;
+
+        for (i = 1; argv[i]; ++i) {
+                void *path;
+                const void *find_ret;
+                const char *type;
+
+                type = path = NULL;
+
+                if (0) {} /* make conditional compile easier below */
+                /*else if ((find_ret = find_alias(argv[i])))
+                        type = "an alias";*/
+#if ENABLE_HUSH_FUNCTIONS
+                else if ((find_ret = find_function(argv[i])))
+                        type = "a function";
+#endif
+                else if ((find_ret = find_builtin(argv[i])))
+                        type = "a shell builtin";
+                else if ((find_ret = path = find_in_path(argv[i])))
+                        type = find_ret;
+
+                if (!type) {
+                        bb_error_msg("type: %s: not found", argv[i]);
+                        ret = EXIT_FAILURE;
+                } else
+                        printf("%s is %s\n", argv[i], type);
+
+                if (path)
+                        free(path);
+        }
+
+        return ret;
+}
+
 #if ENABLE_HUSH_JOB
 /* built-in 'fg' and 'bg' handler */
 static int builtin_fg_bg(char **argv)
@@ -6986,7 +7058,7 @@ static int builtin_shift(char **argv)
 
 static int builtin_source(char **argv)
 {
-        const char *PATH;
+        char *arg_path;
         FILE *input;
         save_arg_t sv;
 #if ENABLE_HUSH_FUNCTIONS
@@ -6996,36 +7068,15 @@ static int builtin_source(char **argv)
         if (*++argv == NULL)
                 return EXIT_FAILURE;
 
-        if (strchr(*argv, '/') == NULL
-         && (PATH = get_local_var_value("PATH")) != NULL
-        ) {
-                /* Search through $PATH */
-                while (1) {
-                        const char *end = strchrnul(PATH, ':');
-                        int sz = end - PATH; /* must be int! */
-
-                        if (sz != 0) {
-                                char *tmp = xasprintf("%.*s/%s", sz, PATH, *argv);
-                                input = fopen_for_read(tmp);
-                                free(tmp);
-                        } else {
-                                /* We have xxx::yyyy in $PATH,
-                                 * it means "use current dir" */
-                                input = fopen_for_read(*argv);
-                        }
-                        if (input)
-                                goto opened_ok;
-                        if (*end == '\0')
-                                break;
-                        PATH = end + 1;
-                }
-        }
-        input = fopen_or_warn(*argv, "r");
+        if (strchr(*argv, '/') == NULL && (arg_path = find_in_path(*argv)) != NULL) {
+                input = fopen_for_read(arg_path);
+                free(arg_path);
+        } else
+                input = fopen_or_warn(*argv, "r");
         if (!input) {
                 /* bb_perror_msg("%s", *argv); - done by fopen_or_warn */
                 return EXIT_FAILURE;
         }
- opened_ok:
         close_on_exec_on(fileno(input));
 
 #if ENABLE_HUSH_FUNCTIONS