hush: wait for `cmd` to complete, and immediately store its exitcode in $?

function                                             old     new   delta
expand_vars_to_list                                 2129    2197     +68

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

4 files changed, 70 insertions, 18 deletions

diff --git a/shell/brace.txt b/shell/brace.txt
new file mode 100644
index 000000000..664861b08
--- /dev/null
+++ b/shell/brace.txt
@@ -0,0 +1,50 @@
+Brace Expansion
+
+Brace expansion is a mechanism by which arbitrary strings may be gener-
+ated.   This  mechanism is similar to pathname expansion, but the file-
+names generated need not exist.  Patterns to be brace expanded take the
+form of an optional preamble, followed by either a series of comma-sep-
+arated strings or a sequence expression between a pair of braces,  fol-
+lowed  by  an  optional  postscript.   The preamble is prefixed to each
+string contained within the braces, and the postscript is then appended
+to each resulting string, expanding left to right.
+
+Brace  expansions  may  be nested.  The results of each expanded string
+are not sorted;  left  to  right  order  is  preserved.   For  example,
+a{d,c,b}e expands into `ade ace abe'.
+
+A  sequence  expression takes the form {x..y}, where x and y are either
+integers or single characters.  When integers are supplied, the expres-
+sion  expands  to each number between x and y, inclusive.  When charac-
+ters are supplied, the expression expands  to  each  character  lexico-
+graphically between x and y, inclusive.  Note that both x and y must be
+of the same type.
+
+Brace expansion is performed before any other expansions, and any char-
+acters  special to other expansions are preserved in the result.  It is
+strictly textual.  Bash does not apply any syntactic interpretation  to
+the context of the expansion or the text between the braces.
+
+A  correctly-formed  brace  expansion must contain unquoted opening and
+closing braces, and at least one unquoted comma  or  a  valid  sequence
+expression.   Any incorrectly formed brace expansion is left unchanged.
+A { or , may be quoted with a backslash to prevent its being considered
+part  of  a brace expression.  To avoid conflicts with parameter expan-
+sion, the string ${ is not considered eligible for brace expansion.
+
+This construct is typically used as shorthand when the common prefix of
+the strings to be generated is longer than in the above example:
+
+       mkdir /usr/local/src/bash/{old,new,dist,bugs}
+or
+       chown root /usr/{ucb/{ex,edit},lib/{ex?.?*,how_ex}}
+
+Brace  expansion  introduces  a  slight incompatibility with historical
+versions of sh.  sh does not treat opening or closing braces  specially
+when  they  appear as part of a word, and preserves them in the output.
+Bash removes braces from words as a  consequence  of  brace  expansion.
+For  example,  a word entered to sh as file{1,2} appears identically in
+the output.  The same word is output as file1 file2 after expansion  by
+bash.   If strict compatibility with sh is desired, start bash with the
++B option or disable brace expansion with the +B option to the set com-
+mand
diff --git a/shell/hush.c b/shell/hush.c
index 891d87be7..6f394d1d5 100644
--- a/shell/hush.c
+++ b/shell/hush.c
@@ -2287,7 +2287,7 @@ static NOINLINE int expand_vars_to_list(o_string *output, int n, char *arg, char
                          * expanded result may need to be globbed
                          * and $IFS-splitted */
                         debug_printf_subst("SUBST '%s' first_ch %x\n", arg, first_ch);
-                        process_command_subs(&subst_result, arg);
+                        G.last_exitcode = process_command_subs(&subst_result, arg);
                         debug_printf_subst("SUBST RES '%s'\n", subst_result.data);
                         val = subst_result.data;
                         goto store_val;
@@ -3904,7 +3904,7 @@ static NOINLINE int run_pipe(struct pipe *pi)
                 /* if someone gives us an empty string: `cmd with empty output` */
                 if (!argv_expanded[0]) {
                         debug_leave();
-                        return 0;
+                        return 0; // or G.last_exitcode? see emptytick.tests
                 }
 
                 x = find_builtin(argv_expanded[0]);
@@ -5202,10 +5202,10 @@ static int fetch_heredocs(int heredoc_cnt, struct parse_context *ctx, struct in_
 
 
 #if ENABLE_HUSH_TICK
-static FILE *generate_stream_from_string(const char *s)
+static FILE *generate_stream_from_string(const char *s, pid_t *pid_p)
 {
-        FILE *pf;
-        int pid, channel[2];
+        pid_t pid;
+        int channel[2];
 # if !BB_MMU
         char **to_free;
 # endif
@@ -5291,6 +5291,7 @@ static FILE *generate_stream_from_string(const char *s)
         }
 
         /* parent */
+        *pid_p = pid;
 # if ENABLE_HUSH_FAST
         G.count_SIGCHLD++;
 //bb_error_msg("[%d] fork in generate_stream_from_string: G.count_SIGCHLD:%d G.handled_SIGCHLD:%d", getpid(), G.count_SIGCHLD, G.handled_SIGCHLD);
@@ -5300,8 +5301,8 @@ static FILE *generate_stream_from_string(const char *s)
         free(to_free);
 # endif
         close(channel[1]);
-        pf = fdopen(channel[0], "r");
-        return pf;
+//TODO: libbb: fdopen_or_die?
+        return fdopen(channel[0], "r");
 }
 
 /* Return code is exit status of the process that is run. */
@@ -5309,9 +5310,10 @@ static int process_command_subs(o_string *dest, const char *s)
 {
         FILE *pf;
         struct in_str pipe_str;
-        int ch, eol_cnt;
+        pid_t pid;
+        int status, ch, eol_cnt;
 
-        pf = generate_stream_from_string(s);
+        pf = generate_stream_from_string(s, &pid);
         if (pf == NULL)
                 return 1;
         close_on_exec_on(fileno(pf));
@@ -5331,16 +5333,14 @@ static int process_command_subs(o_string *dest, const char *s)
                 o_addQchr(dest, ch);
         }
 
-        debug_printf("done reading from pipe, pclose()ing\n");
-        /* Note: we got EOF, and we just close the read end of the pipe.
-         * We do not wait for the `cmd` child to terminate. bash and ash do.
-         * Try these:
-         * echo `echo Hi; exec 1>&-; sleep 2` - bash waits 2 sec
-         * `false`; echo $? - bash outputs "1"
-         */
+        debug_printf("done reading from `cmd` pipe, closing it\n");
         fclose(pf);
-        debug_printf("closed FILE from child. return 0\n");
-        return 0;
+        /* We need to extract exitcode. Test case
+         * "true; echo `sleep 1; false` $?"
+         * should print 1 */
+        safe_waitpid(pid, &status, 0);
+        debug_printf("child exited. returning its exitcode:%d\n", WEXITSTATUS(status));
+        return WEXITSTATUS(status);
 }
 #endif /* ENABLE_HUSH_TICK */
 
diff --git a/shell/hush_test/hush-psubst/tick5.right b/shell/hush_test/hush-psubst/tick5.right
new file mode 100644
index 000000000..d00491fd7
--- /dev/null
+++ b/shell/hush_test/hush-psubst/tick5.right
@@ -0,0 +1 @@
+1
diff --git a/shell/hush_test/hush-psubst/tick5.tests b/shell/hush_test/hush-psubst/tick5.tests
new file mode 100755
index 000000000..bd160c9fc
--- /dev/null
+++ b/shell/hush_test/hush-psubst/tick5.tests
@@ -0,0 +1 @@
+true; echo `false` $?