char **argv; /* program name and arguments */
struct pipe *group; /* if non-NULL, first in group or subshell */
struct redir_struct *redirects; /* I/O redirections */
- struct pipe *family; /* pointer back to the child's parent pipe */
};
/* argv vector may contain variable references (^Cvar^C, ^C0^C etc)
* and on execution these are substituted with their values.
ctx->pipe = ctx->list_head = new_pipe();
/* Create the memory for child, roughly:
* ctx->pipe->progs = new struct child_prog;
- * ctx->pipe->progs[0].family = ctx->pipe;
* ctx->child = &ctx->pipe->progs[0];
*/
done_command(ctx);
{
struct child_prog *child = ctx->child;
+ debug_printf_parse("done_word entered: '%s' %p\n", word->data, child);
/* If this word wasn't an assignment, next ones definitely
* can't be assignments. Even if they look like ones. */
if (word->o_assignment != DEFINITELY_ASSIGNMENT) {
} else {
word->o_assignment = MAYBE_ASSIGNMENT;
}
-
- debug_printf_parse("done_word entered: '%s' %p\n", word->data, child);
if (word->length == 0 && word->nonnull == 0) {
debug_printf_parse("done_word return 0: true null, ignored\n");
return 0;
word->o_assignment = NOT_ASSIGNMENT;
debug_printf("word stored in rd_filename: '%s'\n", word->data);
} else {
-// if (child->group) { /* TODO: example how to trigger? */
-// syntax(NULL);
-// debug_printf_parse("done_word return 1: syntax error, groups and arglists don't mix\n");
-// return 1;
-// }
+ /* "{ echo foo; } echo bar" - bad */
+ /* NB: bash allows e.g. "if true; then { echo foo; } fi". TODO? */
+ if (child->group) {
+ syntax(NULL);
+ debug_printf_parse("done_word return 1: syntax error, groups and arglists don't mix\n");
+ return 1;
+ }
#if HAS_KEYWORDS
#if ENABLE_HUSH_CASE
if (ctx->ctx_dsemicolon) {
- /* already done when ctx_dsemicolon was set to 1 */
+ /* already done when ctx_dsemicolon was set to 1: */
/* ctx->ctx_res_w = RES_MATCH; */
ctx->ctx_dsemicolon = 0;
} else
* child structure is not counted in pi->num_progs. */
pi->progs = xrealloc(pi->progs, sizeof(*pi->progs) * (pi->num_progs+1));
child = &pi->progs[pi->num_progs];
-
memset(child, 0, sizeof(*child));
- child->family = pi;
ctx->child = child;
/* but ctx->pipe and ctx->list_head remain unchanged */
int not_null;
debug_printf_parse("done_pipe entered, followup %d\n", type);
- not_null = done_command(ctx); /* implicit closure of previous command */
+ /* Close previous command */
+ not_null = done_command(ctx);
ctx->pipe->followup = type;
IF_HAS_KEYWORDS(ctx->pipe->pi_inverted = ctx->ctx_inverted;)
IF_HAS_KEYWORDS(ctx->ctx_inverted = 0;)
IF_HAS_KEYWORDS(ctx->pipe->res_word = ctx->ctx_res_w;)
+
/* Without this check, even just <enter> on command line generates
* tree of three NOPs (!). Which is harmless but annoying.
* IOW: it is safe to do it unconditionally.
* RES_NONE case is for "for a in; do ..." (empty IN set)
* to work, possibly other cases too. */
if (not_null IF_HAS_KEYWORDS(|| ctx->ctx_res_w != RES_NONE)) {
- struct pipe *new_p = new_pipe();
+ struct pipe *new_p;
+ debug_printf_parse("done_pipe: adding new pipe: "
+ " not_null:%d ctx->ctx_res_w:%d\n",
+ not_null, ctx->ctx_res_w);
+ new_p = new_pipe();
ctx->pipe->next = new_p;
ctx->pipe = new_p;
ctx->child = NULL; /* needed! */
- /* RES_IF, RES_WHILE etc are "sticky" -
+ /* RES_THEN, RES_DO etc are "sticky" -
* they remain set for commands inside if/while.
* This is used to control execution.
* RES_FOR and RES_IN are NOT sticky (needed to support
#endif
/* Create the memory for child, roughly:
* ctx->pipe->progs = new struct child_prog;
- * ctx->pipe->progs[0].family = ctx->pipe;
* ctx->child = &ctx->pipe->progs[0];
*/
done_command(ctx);
+2008-07-14
+
+ Command parsing
+
+Command parsing results in "pipe" structures. "Pipe" structure
+does not always correspond to what sh language calls "pipe",
+it also controls execution of if, while, etc statements.
+
+struct pipe fields:
+ smallint res_word - "none" for normal commands,
+ "if" for if condition etc
+ struct child_prog progs[] - array of commands in pipe
+ smallint followup - how this pipe is related to next: is it
+ "pipe; pipe", "pipe & pipe" "pipe && pipe",
+ "pipe || pipe"?
+
+Blocks of commands { pipe; pipe; } and (pipe; pipe) are represented
+as one pipe struct with one progs[0] element which is a "group" -
+struct child_prog can contain a list of pipes. Sometimes these
+"groups" are created implicitly, e.g. every control
+statement (if, while, etc) sits inside its own "pipe" struct).
+
+res_word controls statement execution. Examples:
+
+"echo Hello" -
+pipe 0 res_word=NONE followup=SEQ prog[0] 'echo' 'Hello'
+pipe 1 res_word=NONE followup=1 SEQ
+
+"echo foo || echo bar" -
+pipe 0 res_word=NONE followup=OR prog[0] 'echo' 'foo'
+pipe 1 res_word=NONE followup=SEQ prog[0] 'echo' 'bar'
+pipe 2 res_word=NONE followup=SEQ
+
+"if true; then echo Hello; true; fi" -
+res_word=NONE followup=SEQ
+ prog 0 group {}:
+ pipe 0 res_word=IF followup=SEQ prog[0] 'true'
+ pipe 1 res_word=THEN followup=SEQ prog[0] 'echo' 'Hello'
+ pipe 2 res_word=THEN followup=SEQ prog[0] 'true'
+ pipe 3 res_word=FI followup=SEQ
+ pipe 4 res_word=NONE followup=(null)
+pipe 1 res_word=NONE followup=SEQ
+
+"if true; then { echo Hello; true; }; fi" -
+pipe 0 res_word=NONE followup=SEQ
+ prog 0 group {}:
+ pipe 0 res_word=IF followup=SEQ prog[0] 'true'
+ pipe 1 res_word=THEN followup=SEQ
+ prog 0 group {}:
+ pipe 0 res_word=NONE followup=SEQ prog[0] 'echo' 'Hello'
+ pipe 1 res_word=NONE followup=SEQ prog[0] 'true'
+ pipe 2 res_word=NONE followup=SEQ
+ pipe 2 res_word=NONE followup=(null)
+pipe 1 res_word=NONE followup=1 SEQ
+
+"for v in a b; do echo $v; true; done" -
+pipe 0 res_word=NONE followup=SEQ
+ prog 0 group {}:
+ pipe 0 res_word=FOR followup=SEQ prog[0] 'v'
+ pipe 1 res_word=IN followup=SEQ prog[0] 'a' 'b'
+ pipe 2 res_word=DO followup=SEQ prog[0] 'echo' '$v'
+ pipe 3 res_word=DO followup=SEQ prog[0] 'true'
+ pipe 4 res_word=DONE followup=SEQ
+ pipe 5 res_word=NONE followup=(null)
+pipe 1 res_word=NONE followup=SEQ
+
+Note how "THEN" and "DO" does not just mark the first pipe,
+it "sticks" to all pipes in the body. This is used when
+hush executes parsed pipes.
+
+Dummy trailing pipes with no commands are artifacts of imperfect
+parsing algorithm - done_pipe() appends new pipe struct beforehand
+and last one ends up empty and unused.
+
+
+2008-01
+
This is how hush runs commands:
/* callsite: process_command_subs */
projects / platform / upstream / busybox.git / commitdiff