hush: print cd error to stderr; use fopen_or_warn in builtin_source;

 prepare builtin_unset for function support
libbb: do not clear errno in fopen_or_warn

function                                             old     new   delta
builtin_unset                                        242     271     +29
fopen_or_warn                                         42      31     -11
builtin_cd                                            90      74     -16
builtin_source                                        89      72     -17
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 1/3 up/down: 29/-44)            Total: -15 bytes

2 files changed, 39 insertions, 25 deletions

diff --git a/libbb/wfopen.c b/libbb/wfopen.c
index 4c84b3ba9..1cb871ef5 100644
--- a/libbb/wfopen.c
+++ b/libbb/wfopen.c
@@ -14,7 +14,7 @@ FILE* FAST_FUNC fopen_or_warn(const char *path, const char *mode)
         FILE *fp = fopen(path, mode);
         if (!fp) {
                 bb_simple_perror_msg(path);
-                errno = 0;
+                //errno = 0; /* why? */
         }
         return fp;
 }
diff --git a/shell/hush.c b/shell/hush.c
index 3cf651b33..bad2c8044 100644
--- a/shell/hush.c
+++ b/shell/hush.c
@@ -5457,17 +5457,16 @@ static int builtin_eval(char **argv)
 
 static int builtin_cd(char **argv)
 {
-        const char *newdir;
-        if (*++argv == NULL) {
+        const char *newdir = argv[1];
+        if (newdir == NULL) {
                 /* bash does nothing (exitcode 0) if HOME is ""; if it's unset,
                  * bash says "bash: cd: HOME not set" and does nothing (exitcode 1)
                  */
                 newdir = getenv("HOME") ? : "/";
-        } else {
-                newdir = *argv;
         }
         if (chdir(newdir)) {
-                printf("cd: %s: %s\n", newdir, strerror(errno));
+                /* Mimic bash message exactly */
+                bb_perror_msg("cd: %s", newdir);
                 return EXIT_FAILURE;
         }
         set_cwd();
@@ -5763,18 +5762,19 @@ static int builtin_source(char **argv)
 {
         FILE *input;
 
-        if (argv[1] == NULL)
+        if (*++argv == NULL)
                 return EXIT_FAILURE;
 
         /* XXX search through $PATH is missing */
-        input = fopen_for_read(argv[1]);
+        input = fopen_or_warn(*argv, "r");
         if (!input) {
-                bb_error_msg("can't open '%s'", argv[1]);
+                /* bb_perror_msg("%s", *argv); - done by fopen_or_warn */
                 return EXIT_FAILURE;
         }
         close_on_exec_on(fileno(input));
 
         /* Now run the file */
+//TODO:
         /* XXX argv and argc are broken; need to save old G.global_argv
          * (pointer only is OK!) on this stack frame,
          * set G.global_argv=argv+1, recurse, and restore. */
@@ -5788,12 +5788,18 @@ static int builtin_umask(char **argv)
         mode_t new_umask;
         const char *arg = argv[1];
         if (arg) {
+//TODO: umask may take chmod-like symbolic masks
                 new_umask = bb_strtou(arg, NULL, 8);
-                if (errno)
+                if (errno) {
+                        //Message? bash examples:
+                        //bash: umask: 'q': invalid symbolic mode operator
+                        //bash: umask: 999: octal number out of range
                         return EXIT_FAILURE;
+                }
         } else {
                 new_umask = umask(0);
                 printf("%.3o\n", (unsigned) new_umask);
+                /* fall through and restore new_umask which we set to 0 */
         }
         umask(new_umask);
         return EXIT_SUCCESS;
@@ -5802,35 +5808,43 @@ static int builtin_umask(char **argv)
 /* http://www.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html#unset */
 static int builtin_unset(char **argv)
 {
-        size_t i;
         int ret;
-        bool var = true;
+        char var;
 
-        if (!argv[1])
+        if (!*++argv)
                 return EXIT_SUCCESS;
 
-        i = 0;
-        if (argv[1][0] == '-') {
-                switch (argv[1][1]) {
-                case 'v': break;
-                case 'f': if (ENABLE_HUSH_FUNCTIONS) { var = false; break; }
+        var = 'v';
+        if (argv[0][0] == '-') {
+                switch (argv[0][1]) {
+                case 'v':
+                case 'f':
+                        var = argv[0][1];
+                        break;
                 default:
-                        bb_error_msg("unset: %s: invalid option", argv[1]);
+                        bb_error_msg("unset: %s: invalid option", *argv);
                         return EXIT_FAILURE;
                 }
-                ++i;
+//TODO: disallow "unset -vf ..." too
+                argv++;
         }
 
         ret = EXIT_SUCCESS;
-        while (argv[++i]) {
-                if (var) {
-                        if (unset_local_var(argv[i]))
+        while (*argv) {
+                if (var == 'v') {
+                        if (unset_local_var(*argv)) {
+                                /* unset <nonexistent_var> doesn't fail.
+                                 * Error is when one tries to unset RO var.
+                                 * Message was printed by unset_local_var. */
                                 ret = EXIT_FAILURE;
+                        }
                 }
 #if ENABLE_HUSH_FUNCTIONS
-                else
-                        unset_local_func(argv[i]);
+                else {
+                        unset_local_func(*argv);
+                }
 #endif
+                argv++;
         }
         return ret;
 }