svn commit: trunk/busybox/shell
vda at busybox.net
vda at busybox.net
Mon Jul 28 15:15:09 UTC 2008
Author: vda
Date: 2008-07-28 08:15:09 -0700 (Mon, 28 Jul 2008)
New Revision: 22968
Log:
hush: explain run_list() in detail; small optimizations
function old new delta
hush_main 785 786 +1
expand_variables 1447 1448 +1
builtin_exit 48 49 +1
builtin_eval 54 55 +1
run_list 2075 2055 -20
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 4/1 up/down: 4/-20) Total: -16 bytes
Modified:
trunk/busybox/shell/hush.c
Changeset:
Modified: trunk/busybox/shell/hush.c
===================================================================
--- trunk/busybox/shell/hush.c 2008-07-28 00:06:02 UTC (rev 22967)
+++ trunk/busybox/shell/hush.c 2008-07-28 15:15:09 UTC (rev 22968)
@@ -431,12 +431,12 @@
#endif
smallint fake_mode;
/* these three support $?, $#, and $1 */
+ smalluint last_return_code;
char **global_argv;
int global_argc;
- int last_return_code;
+ pid_t last_bg_pid;
const char *ifs;
const char *cwd;
- unsigned last_bg_pid;
struct variable *top_var; /* = &shell_ver (set in main()) */
struct variable shell_ver;
#if ENABLE_FEATURE_SH_STANDALONE
@@ -2012,54 +2012,53 @@
* global data until exec/_exit (we can be a child after vfork!) */
static int run_list(struct pipe *pi)
{
- struct pipe *rpipe;
+#if ENABLE_HUSH_CASE
+ char *case_word = NULL;
+#endif
#if ENABLE_HUSH_LOOPS
+ struct pipe *loop_top;
char *for_varname = NULL;
char **for_lcur = NULL;
char **for_list = NULL;
- int flag_rep = 0;
+ smallint flag_run_loop = 0;
+ smallint flag_goto_looptop = 0;
#endif
-#if ENABLE_HUSH_CASE
- char *case_word = NULL;
-#endif
- int flag_skip = 1;
- int rcode = 0; /* probably for gcc only */
- int flag_restore = 0;
+ smallint flag_skip = 1;
+ smalluint rcode = 0; /* probably for gcc only */
#if ENABLE_HUSH_IF
- int if_code = 0, next_if_code = 0; /* need double-buffer to handle elif */
+ smalluint cond_code = 0;
+ smalluint last_cond_code = 0; /* need double-buffer to handle "elif" */
#else
- enum { if_code = 0, next_if_code = 0 };
+ enum { cond_code = 0, last_cond_code = 0 };
#endif
- reserved_style rword IF_HAS_NO_KEYWORDS(= RES_NONE);
- reserved_style skip_more_for_this_rword = RES_XXXX;
+ /*reserved_style*/ smallint rword IF_HAS_NO_KEYWORDS(= RES_NONE);
+ /*reserved_style*/ smallint skip_more_for_this_rword = RES_XXXX;
debug_printf_exec("run_list start lvl %d\n", run_list_level + 1);
#if ENABLE_HUSH_LOOPS
/* check syntax for "for" */
- for (rpipe = pi; rpipe; rpipe = rpipe->next) {
- if (rpipe->res_word != RES_FOR && rpipe->res_word != RES_IN)
+ for (loop_top = pi; loop_top; loop_top = loop_top->next) {
+ if (loop_top->res_word != RES_FOR && loop_top->res_word != RES_IN)
continue;
/* current word is FOR or IN (BOLD in comments below) */
- if (rpipe->next == NULL) {
+ if (loop_top->next == NULL) {
syntax("malformed for");
debug_printf_exec("run_list lvl %d return 1\n", run_list_level);
return 1;
}
/* "FOR v; do ..." and "for v IN a b; do..." are ok */
- if (rpipe->next->res_word == RES_DO)
+ if (loop_top->next->res_word == RES_DO)
continue;
/* next word is not "do". It must be "in" then ("FOR v in ...") */
- if (rpipe->res_word == RES_IN /* "for v IN a b; not_do..."? */
- || rpipe->next->res_word != RES_IN /* FOR v not_do_and_not_in..."? */
+ if (loop_top->res_word == RES_IN /* "for v IN a b; not_do..."? */
+ || loop_top->next->res_word != RES_IN /* FOR v not_do_and_not_in..."? */
) {
syntax("malformed for");
debug_printf_exec("run_list lvl %d return 1\n", run_list_level);
return 1;
}
}
-#else
- rpipe = NULL;
#endif
/* Past this point, all code paths should jump to ret: label
@@ -2108,21 +2107,24 @@
}
#endif /* JOB */
- for (; pi; pi = flag_restore ? rpipe : pi->next) {
+ /* Go through list of pipes, (maybe) executing them */
+ for (; pi; pi = USE_HUSH_LOOPS( flag_goto_looptop ? loop_top : ) pi->next) {
IF_HAS_KEYWORDS(rword = pi->res_word;)
IF_HAS_NO_KEYWORDS(rword = RES_NONE;)
+ debug_printf_exec(": rword=%d cond_code=%d last_cond_code=%d skip_more=%d flag_run_loop=%d\n",
+ rword, cond_code, last_cond_code, skip_more_for_this_rword, flag_run_loop);
#if ENABLE_HUSH_LOOPS
if (rword == RES_WHILE || rword == RES_UNTIL || rword == RES_FOR) {
- flag_restore = 0;
- if (!rpipe) {
- flag_rep = 0;
- rpipe = pi;
+ /* start of a loop: remember it */
+ flag_goto_looptop = 0; /* not yet reached final "done" */
+ if (!loop_top) { /* hmm why this check is needed? */
+ flag_run_loop = 0; /* suppose loop condition is false (for now) */
+ loop_top = pi; /* remember where loop starts */
}
}
#endif
- debug_printf_exec(": rword=%d if_code=%d next_if_code=%d skip_more=%d\n",
- rword, if_code, next_if_code, skip_more_for_this_rword);
if (rword == skip_more_for_this_rword && flag_skip) {
+ /* it is "<false> && CMD ... */
if (pi->followup == PIPE_SEQ)
flag_skip = 0;
continue;
@@ -2131,13 +2133,14 @@
skip_more_for_this_rword = RES_XXXX;
#if ENABLE_HUSH_IF
if (rword == RES_THEN || rword == RES_ELSE)
- if_code = next_if_code;
- if (rword == RES_THEN && if_code)
- continue;
- if (rword == RES_ELSE && !if_code)
- continue;
- if (rword == RES_ELIF && !if_code)
- break;
+ cond_code = last_cond_code;
+ if (rword == RES_THEN && cond_code)
+ continue; /* "if <false> THEN cmd": skip cmd */
+ if (rword == RES_ELSE && !cond_code)
+ continue; /* "if <true> then ... ELSE cmd": skip cmd */
+// TODO: break;?
+ if (rword == RES_ELIF && !cond_code)
+ break; /* "if <true> then ... ELIF cmd": skip cmd and all following ones */
#endif
#if ENABLE_HUSH_LOOPS
if (rword == RES_FOR && pi->num_progs) {
@@ -2153,7 +2156,7 @@
char **vals;
vals = (char**)encoded_dollar_at_argv;
- if (rpipe->next->res_word == RES_IN) {
+ if (loop_top->next->res_word == RES_IN) {
/* if no variable values after "in" we skip "for" */
if (!pi->next->progs->argv)
continue;
@@ -2166,7 +2169,7 @@
debug_print_strings("for_list", for_list);
for_varname = pi->progs->argv[0];
pi->progs->argv[0] = NULL;
- flag_rep = 1;
+ flag_run_loop = 1; /* "for" has no loop condition, loop... */
}
free(pi->progs->argv[0]);
if (!*for_lcur) {
@@ -2174,26 +2177,27 @@
free(for_list);
for_list = NULL;
for_lcur = NULL;
- flag_rep = 0;
+ flag_run_loop = 0; /* ... until end of value list */
pi->progs->argv[0] = for_varname;
continue;
}
/* insert next value from for_lcur */
- /* vda: does it need escaping? */
+//TODO: does it need escaping?
pi->progs->argv[0] = xasprintf("%s=%s", for_varname, *for_lcur++);
}
- if (rword == RES_IN)
+ if (rword == RES_IN) /* "for v IN list; do ..." - no pipe to execute here */
continue;
- if (rword == RES_DO) {
- if (!flag_rep)
- continue;
+ if (rword == RES_DO) { /* "...; DO cmd; cmd" - this pipe is in loop body */
+ if (!flag_run_loop)
+ continue; /* we are skipping this iteration */
}
- if (rword == RES_DONE) {
- if (flag_rep) {
- flag_restore = 1;
+ if (rword == RES_DONE) { /* end of loop? */
+ if (flag_run_loop) {
+ flag_goto_looptop = 1;
} else {
- rpipe = NULL;
+ loop_top = NULL;
}
+//TODO: continue;? DONE has no cmd anyway
}
#endif
#if ENABLE_HUSH_CASE
@@ -2203,69 +2207,82 @@
continue;
}
if (rword == RES_MATCH) {
- if (case_word) {
- char *pattern = expand_strvec_to_string(pi->progs->argv);
- /* TODO: which FNM_xxx flags to use? */
- next_if_code = fnmatch(pattern, case_word, /*flags:*/ 0);
- //bb_error_msg("fnmatch('%s','%s'):%d", pattern, case_word, next_if_code);
- free(pattern);
- if (next_if_code == 0) {
- free(case_word);
- case_word = NULL;
- }
- continue;
+ char *pattern;
+ if (!case_word) /* "case ... matched_word) ... WORD)": we executed selected branch, stop */
+ break;
+ /* all prev words didn't match, does this one match? */
+ pattern = expand_strvec_to_string(pi->progs->argv);
+ /* TODO: which FNM_xxx flags to use? */
+ last_cond_code = (fnmatch(pattern, case_word, /*flags:*/ 0) != 0);
+ //bb_error_msg("fnmatch('%s','%s'):%d", pattern, case_word, last_cond_code);
+ free(pattern);
+ if (last_cond_code == 0) { /* match! we will execute this branch */
+ free(case_word); /* make future "word)" stop */
+ case_word = NULL;
}
- break;
+ continue;
}
- if (rword == RES_CASEI) {
- if (next_if_code != 0)
- continue;
+ if (rword == RES_CASEI) { /* inside of a case branch */
+ if (last_cond_code != 0)
+ continue; /* not matched yet, skip this pipe */
}
#endif
-
if (pi->num_progs == 0)
continue;
+
+ /* After analyzing all keywrds and conditions, we decided
+ * to execute this pipe */
debug_printf_exec(": run_pipe with %d members\n", pi->num_progs);
- rcode = run_pipe(pi);
- if (rcode != -1) {
- /* We only ran a builtin: rcode was set by the return value
- * of run_pipe(), and we don't need to wait for anything. */
- } else if (pi->followup == PIPE_BG) {
- /* What does bash do with attempts to background builtins? */
- /* Even bash 3.2 doesn't do that well with nested bg:
- * try "{ { sleep 10; echo DEEP; } & echo HERE; } &".
- * I'm NOT treating inner &'s as jobs */
+ {
+ int r;
+ rcode = r = run_pipe(pi); /* NB: rcode is a smallint */
+ if (r != -1) {
+ /* We only ran a builtin: rcode was set by the return value
+ * of run_pipe(), and we don't need to wait for anything. */
+ } else if (pi->followup == PIPE_BG) {
+ /* What does bash do with attempts to background builtins? */
+ /* Even bash 3.2 doesn't do that well with nested bg:
+ * try "{ { sleep 10; echo DEEP; } & echo HERE; } &".
+ * I'm NOT treating inner &'s as jobs */
#if ENABLE_HUSH_JOB
- if (run_list_level == 1)
- insert_bg_job(pi);
+ if (run_list_level == 1)
+ insert_bg_job(pi);
#endif
- rcode = EXIT_SUCCESS;
- } else {
+ rcode = 0; /* EXIT_SUCCESS */
+ } else {
#if ENABLE_HUSH_JOB
- if (run_list_level == 1 && interactive_fd) {
- /* waits for completion, then fg's main shell */
- rcode = checkjobs_and_fg_shell(pi);
- } else
+ if (run_list_level == 1 && interactive_fd) {
+ /* waits for completion, then fg's main shell */
+ rcode = checkjobs_and_fg_shell(pi);
+ debug_printf_exec(": checkjobs_and_fg_shell returned %d\n", rcode);
+ } else
#endif
- { /* this one just waits for completion */
- rcode = checkjobs(pi);
+ { /* this one just waits for completion */
+ rcode = checkjobs(pi);
+ debug_printf_exec(": checkjobs returned %d\n", rcode);
+ }
}
- debug_printf_exec(": checkjobs returned %d\n", rcode);
}
debug_printf_exec(": setting last_return_code=%d\n", rcode);
last_return_code = rcode;
+
+ /* Analyze how result affects subsequent commands */
#if ENABLE_HUSH_IF
if (rword == RES_IF || rword == RES_ELIF)
- next_if_code = rcode; /* can be overwritten a number of times */
+ last_cond_code = rcode;
#endif
#if ENABLE_HUSH_LOOPS
- if (rword == RES_WHILE)
- flag_rep = !last_return_code;
- if (rword == RES_UNTIL)
- flag_rep = last_return_code;
+ if (rword == RES_WHILE) {
+ flag_run_loop = !rcode;
+ debug_printf_exec(": setting flag_run_loop=%d\n", flag_run_loop);
+ }
+ if (rword == RES_UNTIL) {
+ flag_run_loop = rcode;
+ debug_printf_exec(": setting flag_run_loop=%d\n", flag_run_loop);
+ }
#endif
- if ((rcode == EXIT_SUCCESS && pi->followup == PIPE_OR)
- || (rcode != EXIT_SUCCESS && pi->followup == PIPE_AND)
+ if ((rcode == 0 && pi->followup == PIPE_OR)
+ || (rcode != 0 && pi->followup == PIPE_AND)
) {
skip_more_for_this_rword = rword;
}
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