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hush: delete unused field in struct child.

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reinstate needed check for invalid syntax.
 document command parsing in hush_doc.txt.
This commit is contained in:
Denis Vlasenko 2008-07-14 06:29:38 +00:00
parent 17f02e79f4
commit 395ae45216
2 changed files with 95 additions and 16 deletions
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34
shell/hush.c
View File

@ -322,7 +322,6 @@ struct child_prog {
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.
@ -2830,7 +2829,6 @@ static void initialize_context(struct p_context *ctx)
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);
@ -2960,6 +2958,7 @@ static int done_word(o_string *word, struct p_context *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) {
@ -2967,8 +2966,6 @@ static int done_word(o_string *word, struct p_context *ctx)
} 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;
@ -2980,15 +2977,17 @@ static int done_word(o_string *word, struct p_context *ctx)
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
@ -3085,9 +3084,7 @@ static int done_command(struct p_context *ctx)
* 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 */
@ -3100,22 +3097,28 @@ static void done_pipe(struct p_context *ctx, pipe_style type)
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
@ -3132,7 +3135,6 @@ static void done_pipe(struct p_context *ctx, pipe_style type)
#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);

77
shell/hush_doc.txt
View File

@ -1,3 +1,80 @@
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 */