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hush: fix "true | exit 3; echo $?" bug

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This commit is contained in:
Denis Vlasenko
2007-05-03 22:45:39 +00:00
parent f2fffd0014
commit e725bfe6e0
2 changed files with 105 additions and 46 deletions
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13
shell/README
View File

@@ -1,5 +1,18 @@
Various bits of what is known about busybox shells, in no particular order.
2007-05-03
hush: update on "sleep 1 | exit 3; echo $?" bug.
parse_stream_outer() repeatedly calls parse_stream().
parse_stream() is now fixed to stop on ';' in this example,
fixing it (parse_stream_outer() will call parse_stream() 1st time,
execute the parse tree, call parse_stream() 2nd time and execute the tree).
But it's not the end of story.
In more complex situations we _must_ parse way farther before executing.
Example #2: "{ sleep 1 | exit 3; echo $?; ...few_lines... } >file".
Because of redirection, we cannot execute 1st pipe before we parse it all.
We probably need to learn to store $var expressions in parse tree.
Debug printing of parse tree would be nice too.
2007-04-28
hush: Ctrl-C and Ctrl-Z for single NOFORK commands are working.
Memory and other resource leaks (opendir) are not addressed

138
shell/hush.c
View File

@@ -89,6 +89,7 @@
/* Finer-grained debug switch */
#define debug_printf_jobs(...) do {} while (0)
#define debug_printf_exec(...) do {} while (0)
#define debug_printf_parse(...) do {} while (0)
#ifndef debug_printf
@@ -111,6 +112,10 @@ static const char *indenter(int i)
#define debug_printf_exec(...) fprintf(stderr, __VA_ARGS__)
#endif
#ifndef debug_printf_parse
#define debug_printf_parse(...) fprintf(stderr, __VA_ARGS__)
#endif
#if !ENABLE_HUSH_INTERACTIVE
#undef ENABLE_FEATURE_EDITING
@@ -259,8 +264,14 @@ static int last_return_code;
extern char **environ; /* This is in <unistd.h>, but protected with __USE_GNU */
/* "globals" within this file */
static const char *ifs;
enum {
MAP_ORDINARY = 0,
MAP_FLOWTROUGH_IF_QUOTED = 1,
MAP_IFS_IF_UNQUOTED = 2, /* flow through if quoted too */
MAP_NEVER_FLOWTROUGH = 3,
};
static unsigned char map[256];
static const char *ifs;
static int fake_mode;
static struct close_me *close_me_head;
static const char *cwd;
@@ -390,13 +401,13 @@ static int done_pipe(struct p_context *ctx, pipe_style type);
/* primary string parsing: */
static int redirect_dup_num(struct in_str *input);
static int redirect_opt_num(o_string *o);
static int process_command_subs(o_string *dest, struct p_context *ctx, struct in_str *input, int subst_end);
static int process_command_subs(o_string *dest, struct p_context *ctx, struct in_str *input, const char *subst_end);
static int parse_group(o_string *dest, struct p_context *ctx, struct in_str *input, int ch);
static const char *lookup_param(const char *src);
static char *make_string(char **inp);
static int handle_dollar(o_string *dest, struct p_context *ctx, struct in_str *input);
static int parse_string(o_string *dest, struct p_context *ctx, const char *src);
static int parse_stream(o_string *dest, struct p_context *ctx, struct in_str *input0, int end_trigger);
static int parse_stream(o_string *dest, struct p_context *ctx, struct in_str *input0, const char *end_trigger);
/* setup: */
static int parse_stream_outer(struct in_str *inp, int flag);
static int parse_string_outer(const char *s, int flag);
@@ -1977,8 +1988,9 @@ static int run_list_real(struct pipe *pi)
{
rcode = checkjobs(pi);
}
debug_printf("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;
pi->num_progs = save_num_progs; /* restore number of programs */
if (rmode == RES_IF || rmode == RES_ELIF)
@@ -2519,7 +2531,7 @@ static int reserved_word(o_string *dest, struct p_context *ctx)
return 0;
}
/* normal return is 0.
/* Normal return is 0.
* Syntax or xglob errors return 1. */
static int done_word(o_string *dest, struct p_context *ctx)
{
@@ -2527,9 +2539,9 @@ static int done_word(o_string *dest, struct p_context *ctx)
glob_t *glob_target;
int gr, flags = 0;
debug_printf("done_word: %s %p\n", dest->data, child);
debug_printf_parse("done_word: '%s' %p\n", dest->data, child);
if (dest->length == 0 && !dest->nonnull) {
debug_printf(" true null, ignored\n");
debug_printf_parse("done_word return 0: true null, ignored\n");
return 0;
}
if (ctx->pending_redirect) {
@@ -2537,24 +2549,31 @@ static int done_word(o_string *dest, struct p_context *ctx)
} else {
if (child->group) {
syntax();
return 1; /* syntax error, groups and arglists don't mix */
debug_printf_parse("done_word return 1: syntax error, groups and arglists don't mix\n");
return 1;
}
if (!child->argv && (ctx->type & FLAG_PARSE_SEMICOLON)) {
debug_printf("checking %s for reserved-ness\n", dest->data);
if (reserved_word(dest, ctx))
debug_printf_parse(": checking %s for reserved-ness\n", dest->data);
if (reserved_word(dest, ctx)) {
debug_printf_parse("done_word return %d\n", (ctx->w == RES_SNTX));
return (ctx->w == RES_SNTX);
}
}
glob_target = &child->glob_result;
if (child->argv) flags |= GLOB_APPEND;
}
gr = xglob(dest, flags, glob_target);
if (gr != 0) return 1;
if (gr != 0) {
debug_printf_parse("done_word return 1: xglob returned %d\n", gr);
return 1;
}
b_reset(dest);
if (ctx->pending_redirect) {
ctx->pending_redirect = NULL;
if (glob_target->gl_pathc != 1) {
bb_error_msg("ambiguous redirect");
debug_printf_parse("done_word return 1: ambiguous redirect\n");
return 1;
}
} else {
@@ -2564,6 +2583,7 @@ static int done_word(o_string *dest, struct p_context *ctx)
done_word(dest, ctx);
done_pipe(ctx, PIPE_SEQ);
}
debug_printf_parse("done_word return 0\n");
return 0;
}
@@ -2614,7 +2634,7 @@ static int done_pipe(struct p_context *ctx, pipe_style type)
{
struct pipe *new_p;
done_command(ctx); /* implicit closure of previous command */
debug_printf("done_pipe, type %d\n", type);
debug_printf_parse("done_pipe, type %d\n", type);
ctx->pipe->followup = type;
ctx->pipe->r_mode = ctx->w;
new_p = new_pipe();
@@ -2710,7 +2730,8 @@ static FILE *generate_stream_from_list(struct pipe *head)
/* this version hacked for testing purposes */
/* return code is exit status of the process that is run. */
static int process_command_subs(o_string *dest, struct p_context *ctx, struct in_str *input, int subst_end)
static int process_command_subs(o_string *dest, struct p_context *ctx,
struct in_str *input, const char *subst_end)
{
int retcode;
o_string result = NULL_O_STRING;
@@ -2732,7 +2753,7 @@ static int process_command_subs(o_string *dest, struct p_context *ctx, struct in
setup_file_in_str(&pipe_str, p);
/* now send results of command back into original context */
retcode = parse_stream(dest, ctx, &pipe_str, '\0');
retcode = parse_stream(dest, ctx, &pipe_str, NULL);
/* XXX In case of a syntax error, should we try to kill the child?
* That would be tough to do right, so just read until EOF. */
if (retcode == 1) {
@@ -2757,21 +2778,25 @@ static int process_command_subs(o_string *dest, struct p_context *ctx, struct in
static int parse_group(o_string *dest, struct p_context *ctx,
struct in_str *input, int ch)
{
int rcode, endch = 0;
int rcode;
const char *endch = NULL;
struct p_context sub;
struct child_prog *child = ctx->child;
debug_printf_parse("parse_group entered\n");
if (child->argv) {
syntax();
return 1; /* syntax error, groups and arglists don't mix */
debug_printf_parse("parse_group return 1: syntax error, groups and arglists don't mix\n");
return 1;
}
initialize_context(&sub);
switch (ch) {
case '(':
endch = ')';
endch = ")";
child->subshell = 1;
break;
case '{':
endch = '}';
endch = "}";
break;
default:
syntax(); /* really logic error */
@@ -2780,6 +2805,8 @@ static int parse_group(o_string *dest, struct p_context *ctx,
done_word(dest, &sub); /* finish off the final word in the subcontext */
done_pipe(&sub, PIPE_SEQ); /* and the final command there, too */
child->group = sub.list_head;
debug_printf_parse("parse_group return %d\n", rcode);
return rcode;
/* child remains "open", available for possible redirects */
}
@@ -2880,7 +2907,7 @@ static int handle_dollar(o_string *dest, struct p_context *ctx, struct in_str *i
break;
case '(':
b_getch(input);
process_command_subs(dest, ctx, input, ')');
process_command_subs(dest, ctx, input, ")");
break;
case '*':
sep[0] = ifs[0];
@@ -2913,12 +2940,12 @@ static int parse_string(o_string *dest, struct p_context *ctx, const char *src)
{
struct in_str foo;
setup_string_in_str(&foo, src);
return parse_stream(dest, ctx, &foo, '\0');
return parse_stream(dest, ctx, &foo, NULL);
}
/* return code is 0 for normal exit, 1 for syntax error */
static int parse_stream(o_string *dest, struct p_context *ctx,
struct in_str *input, int end_trigger)
struct in_str *input, const char *end_trigger)
{
int ch, m;
int redir_fd;
@@ -2929,30 +2956,38 @@ static int parse_stream(o_string *dest, struct p_context *ctx,
* A single-quote triggers a bypass of the main loop until its mate is
* found. When recursing, quote state is passed in via dest->quote. */
debug_printf("parse_stream, end_trigger=%d\n", end_trigger);
debug_printf_parse("parse_stream entered, end_trigger='%s'\n", end_trigger);
while ((ch = b_getch(input)) != EOF) {
m = map[ch];
next = (ch == '\n') ? 0 : b_peek(input);
debug_printf("parse_stream: ch=%c (%d) m=%d quote=%d\n",
debug_printf_parse(": ch=%c (%d) m=%d quote=%d\n",
ch, ch, m, dest->quote);
if (m == 0 || ((m == 1 || m == 2) && dest->quote)) {
if (m == MAP_ORDINARY
|| (m != MAP_NEVER_FLOWTROUGH && dest->quote)
) {
b_addqchr(dest, ch, dest->quote);
continue;
}
if (m == 2) { /* unquoted IFS */
if (m == MAP_IFS_IF_UNQUOTED) {
if (done_word(dest, ctx)) {
debug_printf_parse("parse_stream return 1\n");
return 1;
}
/* If we aren't performing a substitution, treat a newline as a
* command separator. */
if (end_trigger != '\0' && ch == '\n')
/* If we aren't performing a substitution, treat
* a newline as a command separator.
* [why we don't handle it exactly like ';'? --vda] */
if (end_trigger && ch == '\n') {
done_pipe(ctx, PIPE_SEQ);
}
}
if (ch == end_trigger && !dest->quote && ctx->w == RES_NONE) {
debug_printf("leaving parse_stream (triggered)\n");
if ((end_trigger && strchr(end_trigger, ch))
&& !dest->quote && ctx->w == RES_NONE
) {
debug_printf_parse("parse_stream return 0\n");
return 0;
}
if (m == 2)
if (m == MAP_IFS_IF_UNQUOTED)
continue;
switch (ch) {
case '#':
@@ -2970,13 +3005,17 @@ static int parse_stream(o_string *dest, struct p_context *ctx,
case '\\':
if (next == EOF) {
syntax();
debug_printf_parse("parse_stream return 1\n");
return 1;
}
b_addqchr(dest, '\\', dest->quote);
b_addqchr(dest, b_getch(input), dest->quote);
break;
case '$':
if (handle_dollar(dest, ctx, input) != 0) return 1;
if (handle_dollar(dest, ctx, input) != 0) {
debug_printf_parse("parse_stream return 1: handle_dollar returned non-0\n");
return 1;
}
break;
case '\'':
dest->nonnull = 1;
@@ -2988,6 +3027,7 @@ static int parse_stream(o_string *dest, struct p_context *ctx,
}
if (ch == EOF) {
syntax();
debug_printf_parse("parse_stream return 1\n");
return 1;
}
break;
@@ -2996,7 +3036,7 @@ static int parse_stream(o_string *dest, struct p_context *ctx,
dest->quote = !dest->quote;
break;
case '`':
process_command_subs(dest, ctx, input, '`');
process_command_subs(dest, ctx, input, "`");
break;
case '>':
redir_fd = redirect_opt_num(dest);
@@ -3007,6 +3047,7 @@ static int parse_stream(o_string *dest, struct p_context *ctx,
b_getch(input);
} else if (next == '(') {
syntax(); /* until we support >(list) Process Substitution */
debug_printf_parse("parse_stream return 1: >(process) not supported\n");
return 1;
}
setup_redirect(ctx, redir_fd, redir_style, input);
@@ -3023,6 +3064,7 @@ static int parse_stream(o_string *dest, struct p_context *ctx,
b_getch(input);
} else if (next == '(') {
syntax(); /* until we support <(list) Process Substitution */
debug_printf_parse("parse_stream return 1: <(process) not supported\n");
return 1;
}
setup_redirect(ctx, redir_fd, redir_style, input);
@@ -3054,28 +3096,32 @@ static int parse_stream(o_string *dest, struct p_context *ctx,
break;
case '(':
case '{':
if (parse_group(dest, ctx, input, ch) != 0)
if (parse_group(dest, ctx, input, ch) != 0) {
debug_printf_parse("parse_stream return 1: parse_group returned non-0\n");
return 1;
}
break;
case ')':
case '}':
syntax(); /* Proper use of this character caught by end_trigger */
syntax(); /* Proper use of this character is caught by end_trigger */
debug_printf_parse("parse_stream return 1: unexpected '}'\n");
return 1;
default:
syntax(); /* this is really an internal logic error */
debug_printf_parse("parse_stream return 1: internal logic error\n");
return 1;
}
}
/* complain if quote? No, maybe we just finished a command substitution
/* Complain if quote? No, maybe we just finished a command substitution
* that was quoted. Example:
* $ echo "`cat foo` plus more"
* and we just got the EOF generated by the subshell that ran "cat foo"
* The only real complaint is if we got an EOF when end_trigger != '\0',
* The only real complaint is if we got an EOF when end_trigger != NULL,
* that is, we were really supposed to get end_trigger, and never got
* one before the EOF. Can't use the standard "syntax error" return code,
* so that parse_stream_outer can distinguish the EOF and exit smoothly. */
debug_printf("leaving parse_stream (EOF)\n");
if (end_trigger != '\0')
debug_printf_parse("parse_stream return -%d\n", end_trigger != NULL);
if (end_trigger)
return -1;
return 0;
}
@@ -3097,17 +3143,17 @@ static void update_ifs_map(void)
* The map[] array only really needs two bits each, and on most machines
* that would be faster because of the reduced L1 cache footprint.
*/
memset(map, 0, sizeof(map)); /* most characters flow through always */
mapset("\\$'\"`", 3); /* never flow through */
mapset("<>;&|(){}#", 1); /* flow through if quoted */
mapset(ifs, 2); /* also flow through if quoted */
memset(map, MAP_ORDINARY, sizeof(map)); /* most chars flow through always */
mapset("\\$'\"`", MAP_NEVER_FLOWTROUGH);
mapset("<>;&|(){}#", MAP_FLOWTROUGH_IF_QUOTED);
mapset(ifs, MAP_IFS_IF_UNQUOTED); /* also flow through if quoted */
}
/* most recursion does not come through here, the exception is
* from builtin_source() */
static int parse_stream_outer(struct in_str *inp, int flag)
{
// FIXME: 'true | exit 3; echo $?' is parsed as a whole,
// FIXME: '{ true | exit 3; echo $? }' is parsed as a whole,
// as a result $? is replaced by 0, not 3!
// Need to stop & execute stuff at ';', not parse till EOL!
@@ -3119,11 +3165,11 @@ static int parse_stream_outer(struct in_str *inp, int flag)
initialize_context(&ctx);
update_ifs_map();
if (!(flag & FLAG_PARSE_SEMICOLON) || (flag & FLAG_REPARSING))
mapset(";$&|", 0);
mapset(";$&|", MAP_ORDINARY);
#if ENABLE_HUSH_INTERACTIVE
inp->promptmode = 1;
#endif
rcode = parse_stream(&temp, &ctx, inp, '\n');
rcode = parse_stream(&temp, &ctx, inp, ";\n");
if (rcode != 1 && ctx.old_flag != 0) {
syntax();
}