More hush updates from Larry:

    Update some comments.  Generate partial placeholders for the missing
    builtins.  Write builtin_umask.  Properly treat exec without arguments
    as a means to open/close files within the running script.  Implement
    "4<&-" that encodes for file descriptor closure.

2 files changed, 108 insertions, 38 deletions

diff --git a/hush.c b/hush.c
index b8e4a55c2..e58ac44b3 100644
--- a/hush.c
+++ b/hush.c
@@ -45,24 +45,25 @@
  *      fancy forms of Parameter Expansion
  *      Arithmetic Expansion
  *      <(list) and >(list) Process Substitution
- *      reserved words: case, esac, function
+ *      reserved words: case, esac, select, function
  *      Here Documents ( << word )
  *      Functions
  * Major bugs:
  *      job handling woefully incomplete and buggy
  *      reserved word execution woefully incomplete and buggy
  * to-do:
- *      port selected bugfixes from post-0.49 busybox lash
- *      finish implementing reserved words
+ *      port selected bugfixes from post-0.49 busybox lash - done?
+ *      finish implementing reserved words: for, while, until, do, done
+ *      change { and } from special chars to reserved words
+ *      builtins: break, continue, eval, return, set, trap, ulimit
+ *      test magic exec
  *      handle children going into background
  *      clean up recognition of null pipes
  *      have builtin_exec set flag to avoid restore_redirects
- *      figure out if "echo foo}" is fixable
  *      check setting of global_argc and global_argv
  *      control-C handling, probably with longjmp
  *      VAR=value prefix for simple commands
  *      follow IFS rules more precisely, including update semantics
- *      write builtin_eval, builtin_ulimit, builtin_umask
  *      figure out what to do with backslash-newline
  *      explain why we use signal instead of sigaction
  *      propagate syntax errors, die on resource errors?
@@ -97,6 +98,7 @@
 #include <fcntl.h>
 #include <getopt.h>    /* should be pretty obvious */
 
+#include <sys/stat.h>  /* ulimit */
 #include <sys/types.h>
 #include <sys/wait.h>
 #include <signal.h>
@@ -323,9 +325,9 @@ static int builtin_pwd(struct child_prog *child);
 static int builtin_read(struct child_prog *child);
 static int builtin_shift(struct child_prog *child);
 static int builtin_source(struct child_prog *child);
-static int builtin_ulimit(struct child_prog *child);
 static int builtin_umask(struct child_prog *child);
 static int builtin_unset(struct child_prog *child);
+static int builtin_not_written(struct child_prog *child);
 /*   o_string manipulation: */
 static int b_check_space(o_string *o, int len);
 static int b_addchr(o_string *o, int ch);
@@ -390,8 +392,11 @@ static void free_pipe(struct pipe *pi);
  * still be set at the end. */
 static struct built_in_command bltins[] = {
         {"bg", "Resume a job in the background", builtin_fg_bg},
+        {"break", "Exit for, while or until loop", builtin_not_written},
         {"cd", "Change working directory", builtin_cd},
+        {"continue", "Continue for, while or until loop", builtin_not_written},
         {"env", "Print all environment variables", builtin_env},
+        {"eval", "Construct and run shell command", builtin_not_written},
         {"exec", "Exec command, replacing this shell with the exec'd process", builtin_exec},
         {"exit", "Exit from shell()", builtin_exit},
         {"export", "Set environment variable", builtin_export},
@@ -399,8 +404,11 @@ static struct built_in_command bltins[] = {
         {"jobs", "Lists the active jobs", builtin_jobs},
         {"pwd", "Print current directory", builtin_pwd},
         {"read", "Input environment variable", builtin_read},
+        {"return", "Return from a function", builtin_not_written},
+        {"set", "Set/unset shell options", builtin_not_written},
         {"shift", "Shift positional parameters", builtin_shift},
-        {"ulimit","Controls resource limits", builtin_ulimit},
+        {"trap", "Trap signals", builtin_not_written},
+        {"ulimit","Controls resource limits", builtin_not_written},
         {"umask","Sets file creation mask", builtin_umask},
         {"unset", "Unset environment variable", builtin_unset},
         {".", "Source-in and run commands in a file", builtin_source},
@@ -640,16 +648,21 @@ static int builtin_source(struct child_prog *child)
         return (status);
 }
 
-static int builtin_ulimit(struct child_prog *child)
-{
-        printf("builtin_ulimit not written\n");
-        return EXIT_FAILURE;
-}
-
 static int builtin_umask(struct child_prog *child)
 {
-        printf("builtin_umask not written\n");
-        return EXIT_FAILURE;
+        mode_t new_umask;
+        const char *arg = child->argv[1];
+        char *end;
+        if (arg) {
+                new_umask=strtoul(arg, &end, 8);
+                if (*end!='\0' || end == arg) {
+                        return EXIT_FAILURE;
+                }
+        } else {
+                printf("%.3o\n", (unsigned int) (new_umask=umask(0)));
+        }
+        umask(new_umask);
+        return EXIT_SUCCESS;
 }
 
 /* built-in 'unset VAR' handler */
@@ -663,6 +676,12 @@ static int builtin_unset(struct child_prog *child)
         return EXIT_SUCCESS;
 }
 
+static int builtin_not_written(struct child_prog *child)
+{
+        printf("builtin_%s not written\n",child->argv[0]);
+        return EXIT_FAILURE;
+}
+
 static int b_check_space(o_string *o, int len)
 {
         /* It would be easy to drop a more restrictive policy
@@ -926,8 +945,12 @@ static int setup_redirects(struct child_prog *prog, int squirrel[])
                         if (squirrel && redir->fd < 3) {
                                 squirrel[redir->fd] = dup(redir->fd);
                         }
-                        dup2(openfd, redir->fd);
-                        close(openfd);
+                        if (openfd == -3) {
+                                close(openfd);
+                        } else {
+                                dup2(openfd, redir->fd);
+                                close(openfd);
+                        }
                 }
         }
         return 0;
@@ -1216,6 +1239,11 @@ static int run_pipe_real(struct pipe *pi)
                         if (strcmp(child->argv[0], x->cmd) == 0 ) {
                                 int squirrel[] = {-1, -1, -1};
                                 int rcode;
+                                if (x->function == builtin_exec && child->argv[1]==NULL) {
+                                        debug_printf("magic exec\n");
+                                        setup_redirects(child,NULL);
+                                        return EXIT_SUCCESS;
+                                }
                                 debug_printf("builtin inline %s\n", child->argv[0]);
                                 /* XXX setup_redirects acts on file descriptors, not FILEs.
                                  * This is perfect for work that comes after exec().
@@ -1569,7 +1597,8 @@ static int setup_redirect(struct p_context *ctx, int fd, redir_type style,
         if (redir->dup == -2) return 1;  /* syntax error */
         if (redir->dup != -1) {
                 /* Erik had a check here that the file descriptor in question
-                 * is legit; I postpone that to "run time" */
+                 * is legit; I postpone that to "run time"
+                 * A "-" representation of "close me" shows up as a -3 here */
                 debug_printf("Duplicating redirect '%d>&%d'\n", redir->fd, redir->dup);
         } else {
                 /* We do _not_ try to open the file that src points to,
@@ -1775,10 +1804,16 @@ static int redirect_dup_num(struct in_str *input)
         if (ch != '&') return -1;
 
         b_getch(input);  /* get the & */
-        while (ch=b_peek(input),isdigit(ch)) {
+        ch=b_peek(input);
+        if (ch == '-') {
+                b_getch(input);
+                return -3;  /* "-" represents "close me" */
+        }
+        while (isdigit(ch)) {
                 d = d*10+(ch-'0');
                 ok=1;
                 b_getch(input);
+                ch = b_peek(input);
         }
         if (ok) return d;
 
diff --git a/shell/hush.c b/shell/hush.c
index b8e4a55c2..e58ac44b3 100644
--- a/shell/hush.c
+++ b/shell/hush.c
@@ -45,24 +45,25 @@
  *      fancy forms of Parameter Expansion
  *      Arithmetic Expansion
  *      <(list) and >(list) Process Substitution
- *      reserved words: case, esac, function
+ *      reserved words: case, esac, select, function
  *      Here Documents ( << word )
  *      Functions
  * Major bugs:
  *      job handling woefully incomplete and buggy
  *      reserved word execution woefully incomplete and buggy
  * to-do:
- *      port selected bugfixes from post-0.49 busybox lash
- *      finish implementing reserved words
+ *      port selected bugfixes from post-0.49 busybox lash - done?
+ *      finish implementing reserved words: for, while, until, do, done
+ *      change { and } from special chars to reserved words
+ *      builtins: break, continue, eval, return, set, trap, ulimit
+ *      test magic exec
  *      handle children going into background
  *      clean up recognition of null pipes
  *      have builtin_exec set flag to avoid restore_redirects
- *      figure out if "echo foo}" is fixable
  *      check setting of global_argc and global_argv
  *      control-C handling, probably with longjmp
  *      VAR=value prefix for simple commands
  *      follow IFS rules more precisely, including update semantics
- *      write builtin_eval, builtin_ulimit, builtin_umask
  *      figure out what to do with backslash-newline
  *      explain why we use signal instead of sigaction
  *      propagate syntax errors, die on resource errors?
@@ -97,6 +98,7 @@
 #include <fcntl.h>
 #include <getopt.h>    /* should be pretty obvious */
 
+#include <sys/stat.h>  /* ulimit */
 #include <sys/types.h>
 #include <sys/wait.h>
 #include <signal.h>
@@ -323,9 +325,9 @@ static int builtin_pwd(struct child_prog *child);
 static int builtin_read(struct child_prog *child);
 static int builtin_shift(struct child_prog *child);
 static int builtin_source(struct child_prog *child);
-static int builtin_ulimit(struct child_prog *child);
 static int builtin_umask(struct child_prog *child);
 static int builtin_unset(struct child_prog *child);
+static int builtin_not_written(struct child_prog *child);
 /*   o_string manipulation: */
 static int b_check_space(o_string *o, int len);
 static int b_addchr(o_string *o, int ch);
@@ -390,8 +392,11 @@ static void free_pipe(struct pipe *pi);
  * still be set at the end. */
 static struct built_in_command bltins[] = {
         {"bg", "Resume a job in the background", builtin_fg_bg},
+        {"break", "Exit for, while or until loop", builtin_not_written},
         {"cd", "Change working directory", builtin_cd},
+        {"continue", "Continue for, while or until loop", builtin_not_written},
         {"env", "Print all environment variables", builtin_env},
+        {"eval", "Construct and run shell command", builtin_not_written},
         {"exec", "Exec command, replacing this shell with the exec'd process", builtin_exec},
         {"exit", "Exit from shell()", builtin_exit},
         {"export", "Set environment variable", builtin_export},
@@ -399,8 +404,11 @@ static struct built_in_command bltins[] = {
         {"jobs", "Lists the active jobs", builtin_jobs},
         {"pwd", "Print current directory", builtin_pwd},
         {"read", "Input environment variable", builtin_read},
+        {"return", "Return from a function", builtin_not_written},
+        {"set", "Set/unset shell options", builtin_not_written},
         {"shift", "Shift positional parameters", builtin_shift},
-        {"ulimit","Controls resource limits", builtin_ulimit},
+        {"trap", "Trap signals", builtin_not_written},
+        {"ulimit","Controls resource limits", builtin_not_written},
         {"umask","Sets file creation mask", builtin_umask},
         {"unset", "Unset environment variable", builtin_unset},
         {".", "Source-in and run commands in a file", builtin_source},
@@ -640,16 +648,21 @@ static int builtin_source(struct child_prog *child)
         return (status);
 }
 
-static int builtin_ulimit(struct child_prog *child)
-{
-        printf("builtin_ulimit not written\n");
-        return EXIT_FAILURE;
-}
-
 static int builtin_umask(struct child_prog *child)
 {
-        printf("builtin_umask not written\n");
-        return EXIT_FAILURE;
+        mode_t new_umask;
+        const char *arg = child->argv[1];
+        char *end;
+        if (arg) {
+                new_umask=strtoul(arg, &end, 8);
+                if (*end!='\0' || end == arg) {
+                        return EXIT_FAILURE;
+                }
+        } else {
+                printf("%.3o\n", (unsigned int) (new_umask=umask(0)));
+        }
+        umask(new_umask);
+        return EXIT_SUCCESS;
 }
 
 /* built-in 'unset VAR' handler */
@@ -663,6 +676,12 @@ static int builtin_unset(struct child_prog *child)
         return EXIT_SUCCESS;
 }
 
+static int builtin_not_written(struct child_prog *child)
+{
+        printf("builtin_%s not written\n",child->argv[0]);
+        return EXIT_FAILURE;
+}
+
 static int b_check_space(o_string *o, int len)
 {
         /* It would be easy to drop a more restrictive policy
@@ -926,8 +945,12 @@ static int setup_redirects(struct child_prog *prog, int squirrel[])
                         if (squirrel && redir->fd < 3) {
                                 squirrel[redir->fd] = dup(redir->fd);
                         }
-                        dup2(openfd, redir->fd);
-                        close(openfd);
+                        if (openfd == -3) {
+                                close(openfd);
+                        } else {
+                                dup2(openfd, redir->fd);
+                                close(openfd);
+                        }
                 }
         }
         return 0;
@@ -1216,6 +1239,11 @@ static int run_pipe_real(struct pipe *pi)
                         if (strcmp(child->argv[0], x->cmd) == 0 ) {
                                 int squirrel[] = {-1, -1, -1};
                                 int rcode;
+                                if (x->function == builtin_exec && child->argv[1]==NULL) {
+                                        debug_printf("magic exec\n");
+                                        setup_redirects(child,NULL);
+                                        return EXIT_SUCCESS;
+                                }
                                 debug_printf("builtin inline %s\n", child->argv[0]);
                                 /* XXX setup_redirects acts on file descriptors, not FILEs.
                                  * This is perfect for work that comes after exec().
@@ -1569,7 +1597,8 @@ static int setup_redirect(struct p_context *ctx, int fd, redir_type style,
         if (redir->dup == -2) return 1;  /* syntax error */
         if (redir->dup != -1) {
                 /* Erik had a check here that the file descriptor in question
-                 * is legit; I postpone that to "run time" */
+                 * is legit; I postpone that to "run time"
+                 * A "-" representation of "close me" shows up as a -3 here */
                 debug_printf("Duplicating redirect '%d>&%d'\n", redir->fd, redir->dup);
         } else {
                 /* We do _not_ try to open the file that src points to,
@@ -1775,10 +1804,16 @@ static int redirect_dup_num(struct in_str *input)
         if (ch != '&') return -1;
 
         b_getch(input);  /* get the & */
-        while (ch=b_peek(input),isdigit(ch)) {
+        ch=b_peek(input);
+        if (ch == '-') {
+                b_getch(input);
+                return -3;  /* "-" represents "close me" */
+        }
+        while (isdigit(ch)) {
                 d = d*10+(ch-'0');
                 ok=1;
                 b_getch(input);
+                ch = b_peek(input);
         }
         if (ok) return d;