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List: busybox
Subject: [PATCH v6] ash: add process substitution in bash-compatibility mode
From: Ron Yorston <rmy () pobox ! com>
Date: 2020-07-23 7:32:27
Message-ID: 5f193d0b.67mflOfbBI7M20Bb%rmy () pobox ! com
[Download RAW message or body]
Process substitution is a Korn shell feature that's also available
in bash and some other shells. This patch implements process
substitution in ash when ASH_BASH_COMPAT is enabled.
function old new delta
argstr 1386 1522 +136
strtodest - 52 +52
readtoken1 3346 3392 +46
.rodata 183206 183250 +44
unwindredir - 28 +28
cmdloop 365 372 +7
static.spclchars 10 12 +2
cmdputs 380 367 -13
exitreset 86 69 -17
evalcommand 1754 1737 -17
varvalue 675 634 -41
------------------------------------------------------------------------------
(add/remove: 2/0 grow/shrink: 5/4 up/down: 315/-88) Total: 227 bytes
text data bss dec hex filename
953967 4219 1904 960090 ea65a busybox_old
954192 4219 1904 960315 ea73b busybox_unstripped
v2: Replace array of file descriptors with a linked list.
Include tests that were unaccountably omitted from v1.
v3: Update linked list code to the intended version.
v4: Change order of conditional code in cmdputs().
v5: Use existing popredir() mechanism to manage file descriptors.
v6: Rebase to latest version of BusyBox ash. Reduce code churn.
Signed-off-by: Ron Yorston <rmy@pobox.com>
---
include/platform.h | 2 +
shell/ash.c | 160 +++++++++++++++++--
shell/ash_test/ash-psubst/bash_procsub.right | 9 ++
shell/ash_test/ash-psubst/bash_procsub.tests | 33 ++++
4 files changed, 187 insertions(+), 17 deletions(-)
create mode 100644 shell/ash_test/ash-psubst/bash_procsub.right
create mode 100755 shell/ash_test/ash-psubst/bash_procsub.tests
diff --git a/include/platform.h b/include/platform.h
index 43bb391bd..233cbe87c 100644
--- a/include/platform.h
+++ b/include/platform.h
@@ -421,6 +421,8 @@ typedef unsigned smalluint;
#define HAVE_NET_ETHERNET_H 1
#define HAVE_SYS_STATFS_H 1
#define HAVE_PRINTF_PERCENTM 1
+#define HAVE_DEV_FD 1
+#define DEV_FD_PREFIX "/dev/fd/"
#if defined(__UCLIBC__)
# if UCLIBC_VERSION < KERNEL_VERSION(0, 9, 32)
diff --git a/shell/ash.c b/shell/ash.c
index ecb9b132b..72bf49896 100644
--- a/shell/ash.c
+++ b/shell/ash.c
@@ -229,6 +229,14 @@
#define BASH_READ_D ENABLE_ASH_BASH_COMPAT
#define IF_BASH_READ_D IF_ASH_BASH_COMPAT
#define BASH_WAIT_N ENABLE_ASH_BASH_COMPAT
+/* <(...) and >(...) */
+#if HAVE_DEV_FD
+# define BASH_PROCESS_SUBST ENABLE_ASH_BASH_COMPAT
+# define IF_BASH_PROCESS_SUBST IF_ASH_BASH_COMPAT
+#else
+# define BASH_PROCESS_SUBST 0
+# define IF_BASH_PROCESS_SUBST(...)
+#endif
#if defined(__ANDROID_API__) && __ANDROID_API__ <= 24
/* Bionic at least up to version 24 has no glob() */
@@ -745,6 +753,12 @@ out2str(const char *p)
#define CTLENDARI ((unsigned char)'\207')
#define CTLQUOTEMARK ((unsigned char)'\210')
#define CTL_LAST CTLQUOTEMARK
+#if BASH_PROCESS_SUBST
+# define CTLTOPROC ((unsigned char)'\211')
+# define CTLFROMPROC ((unsigned char)'\212')
+# undef CTL_LAST
+# define CTL_LAST CTLFROMPROC
+#endif
/* variable substitution byte (follows CTLVAR) */
#define VSTYPE 0x0f /* type of variable substitution */
@@ -1016,6 +1030,10 @@ trace_puts_quoted(char *s)
case CTLESC: c = 'e'; goto backslash;
case CTLVAR: c = 'v'; goto backslash;
case CTLBACKQ: c = 'q'; goto backslash;
+#if BASH_PROCESS_SUBST
+ case CTLTOPROC: c = 'p'; goto backslash;
+ case CTLFROMPROC: c = 'P'; goto backslash;
+#endif
backslash:
putc('\\', tracefile);
putc(c, tracefile);
@@ -1177,8 +1195,17 @@ sharg(union node *arg, FILE *fp)
case CTLENDVAR:
putc('}', fp);
break;
+#if BASH_PROCESS_SUBST
+ case CTLTOPROC:
+ putc('>', fp);
+ goto backq;
+ case CTLFROMPROC:
+ putc('<', fp);
+ goto backq;
+#endif
case CTLBACKQ:
putc('$', fp);
+ IF_BASH_PROCESS_SUBST(backq:)
putc('(', fp);
shtree(bqlist->n, -1, NULL, fp);
putc(')', fp);
@@ -3230,8 +3257,13 @@ static const uint8_t syntax_index_table[] ALIGN1 = {
/* 134 CTLARI */ CCTL_CCTL_CCTL_CCTL,
/* 135 CTLENDARI */ CCTL_CCTL_CCTL_CCTL,
/* 136 CTLQUOTEMARK */ CCTL_CCTL_CCTL_CCTL,
+#if BASH_PROCESS_SUBST
+ /* 137 CTLTOPROC */ CCTL_CCTL_CCTL_CCTL,
+ /* 138 CTLFROMPROC */ CCTL_CCTL_CCTL_CCTL,
+#else
/* 137 */ CWORD_CWORD_CWORD_CWORD,
/* 138 */ CWORD_CWORD_CWORD_CWORD,
+#endif
/* 139 */ CWORD_CWORD_CWORD_CWORD,
/* 140 */ CWORD_CWORD_CWORD_CWORD,
/* 141 */ CWORD_CWORD_CWORD_CWORD,
@@ -4857,9 +4889,24 @@ cmdputs(const char *s)
quoted >>= 1;
subtype = 0;
goto dostr;
+#if BASH_PROCESS_SUBST
+ case CTLBACKQ:
+ c = '$';
+ str = "(...)";
+ break;
+ case CTLTOPROC:
+ c = '>';
+ str = "(...)";
+ break;
+ case CTLFROMPROC:
+ c = '<';
+ str = "(...)";
+ break;
+#else
case CTLBACKQ:
str = "$(...)";
goto dostr;
+#endif
#if ENABLE_FEATURE_SH_MATH
case CTLARI:
str = "$((";
@@ -5899,6 +5946,21 @@ redirectsafe(union node *redir, int flags)
return err;
}
+#if BASH_PROCESS_SUBST
+static void
+pushfd(int fd)
+{
+ struct redirtab *sv;
+
+ sv = ckzalloc(sizeof(*sv) + sizeof(sv->two_fd[0]));
+ sv->pair_count = 1;
+ sv->two_fd[0].orig_fd = fd;
+ sv->two_fd[0].moved_to = CLOSED;
+ sv->next = redirlist;
+ redirlist = sv;
+}
+#endif
+
static struct redirtab*
pushredir(union node *redir)
{
@@ -6537,10 +6599,20 @@ evaltreenr(union node *n, int flags)
}
static void FAST_FUNC
-evalbackcmd(union node *n, struct backcmd *result)
+evalbackcmd(union node *n, struct backcmd *result
+ IF_BASH_PROCESS_SUBST(, int ctl))
{
int pip[2];
struct job *jp;
+#if BASH_PROCESS_SUBST
+ /* determine end of pipe used by parent (ip) and child (ic) */
+ const int ip = (ctl == CTLTOPROC);
+ const int ic = !(ctl == CTLTOPROC);
+#else
+ const int ctl = CTLBACKQ;
+ const int ip = 0;
+ const int ic = 1;
+#endif
result->fd = -1;
result->buf = NULL;
@@ -6552,15 +6624,17 @@ evalbackcmd(union node *n, struct backcmd *result)
if (pipe(pip) < 0)
ash_msg_and_raise_perror("can't create pipe");
- jp = makejob(/*n,*/ 1);
- if (forkshell(jp, n, FORK_NOJOB) == 0) {
+ /* process substitution uses NULL job/node, like openhere() */
+ jp = (ctl == CTLBACKQ) ? makejob(/*n,*/ 1) : NULL;
+ if (forkshell(jp, (ctl == CTLBACKQ) ? n : NULL, FORK_NOJOB) == 0) {
/* child */
FORCE_INT_ON;
- close(pip[0]);
- if (pip[1] != 1) {
- /*close(1);*/
- dup2_or_raise(pip[1], 1);
- close(pip[1]);
+ close(pip[ip]);
+ /* ic is index of child end of pipe *and* fd to connect it to */
+ if (pip[ic] != ic) {
+ /*close(ic);*/
+ dup2_or_raise(pip[ic], ic);
+ close(pip[ic]);
}
/* TODO: eflag clearing makes the following not abort:
* ash -c 'set -e; z=$(false;echo foo); echo $z'
@@ -6576,8 +6650,18 @@ evalbackcmd(union node *n, struct backcmd *result)
/* NOTREACHED */
}
/* parent */
- close(pip[1]);
- result->fd = pip[0];
+#if BASH_PROCESS_SUBST
+ if (ctl != CTLBACKQ) {
+ int fd = fcntl(pip[ip], F_DUPFD, 64);
+ if (fd > 0) {
+ close(pip[ip]);
+ pip[ip] = fd;
+ }
+ pushfd(pip[ip]);
+ }
+#endif
+ close(pip[ic]);
+ result->fd = pip[ip];
result->jp = jp;
out:
@@ -6589,8 +6673,11 @@ evalbackcmd(union node *n, struct backcmd *result)
* Expand stuff in backwards quotes.
*/
static void
-expbackq(union node *cmd, int flag)
+expbackq(union node *cmd, int flag IF_BASH_PROCESS_SUBST(, int ctl))
{
+#if !BASH_PROCESS_SUBST
+ const int ctl = CTLBACKQ;
+#endif
struct backcmd in;
int i;
char buf[128];
@@ -6605,9 +6692,15 @@ expbackq(union node *cmd, int flag)
INT_OFF;
startloc = expdest - (char *)stackblock();
pushstackmark(&smark, startloc);
- evalbackcmd(cmd, &in);
+ evalbackcmd(cmd, &in IF_BASH_PROCESS_SUBST(, ctl));
popstackmark(&smark);
+ if (ctl != CTLBACKQ) {
+ sprintf(buf, DEV_FD_PREFIX"%d", in.fd);
+ strtodest(buf, BASESYNTAX);
+ goto done;
+ }
+
p = in.buf;
i = in.nleft;
if (i == 0)
@@ -6629,6 +6722,7 @@ expbackq(union node *cmd, int flag)
close(in.fd);
back_exitstatus = waitforjob(in.jp);
}
+ IF_BASH_PROCESS_SUBST(done:)
INT_ON;
/* Eat all trailing newlines */
@@ -6716,6 +6810,10 @@ argstr(char *p, int flag)
CTLESC,
CTLVAR,
CTLBACKQ,
+#if BASH_PROCESS_SUBST
+ CTLTOPROC,
+ CTLFROMPROC,
+#endif
#if ENABLE_FEATURE_SH_MATH
CTLARI,
CTLENDARI,
@@ -6815,8 +6913,12 @@ argstr(char *p, int flag)
p = evalvar(p, flag | inquotes);
TRACE(("argstr: evalvar:'%s'\n", (char *)stackblock()));
goto start;
+#if BASH_PROCESS_SUBST
+ case CTLTOPROC:
+ case CTLFROMPROC:
+#endif
case CTLBACKQ:
- expbackq(argbackq->n, flag | inquotes);
+ expbackq(argbackq->n, flag | inquotes IF_BASH_PROCESS_SUBST(, c));
goto start;
#if ENABLE_FEATURE_SH_MATH
case CTLARI:
@@ -12203,8 +12305,9 @@ realeofmark(const char *eofmark)
#define CHECKEND() {goto checkend; checkend_return:;}
#define PARSEREDIR() {goto parseredir; parseredir_return:;}
#define PARSESUB() {goto parsesub; parsesub_return:;}
-#define PARSEBACKQOLD() {oldstyle = 1; goto parsebackq; parsebackq_oldreturn:;}
-#define PARSEBACKQNEW() {oldstyle = 0; goto parsebackq; parsebackq_newreturn:;}
+#define PARSEBACKQOLD() {style = OLD; goto parsebackq; parsebackq_oldreturn:;}
+#define PARSEBACKQNEW() {style = NEW; goto parsebackq; parsebackq_newreturn:;}
+#define PARSEPROCSUB() {style = PSUB; goto parsebackq; parsebackq_psreturn:;}
#define PARSEARITH() {goto parsearith; parsearith_return:;}
static int
readtoken1(int c, int syntax, char *eofmark, int striptabs)
@@ -12215,7 +12318,9 @@ readtoken1(int c, int syntax, char *eofmark, int striptabs)
size_t len;
struct nodelist *bqlist;
smallint quotef;
- smallint oldstyle;
+ smallint style;
+ enum { OLD, NEW, PSUB };
+#define oldstyle style == OLD
smallint pssyntax; /* we are expanding a prompt string */
IF_BASH_DOLLAR_SQUOTE(smallint bash_dollar_squote = 0;)
/* syntax stack */
@@ -12396,6 +12501,15 @@ readtoken1(int c, int syntax, char *eofmark, int striptabs)
c = 0x100 + '>'; /* flag &> */
pungetc();
}
+#endif
+#if BASH_PROCESS_SUBST
+ if (c == '<' || c == '>') {
+ if (pgetc() == '(') {
+ PARSEPROCSUB();
+ break;
+ }
+ pungetc();
+ }
#endif
goto endword; /* exit outer loop */
}
@@ -12881,9 +12995,18 @@ parsebackq: {
memcpy(out, str, savelen);
STADJUST(savelen, out);
}
- USTPUTC(CTLBACKQ, out);
+#if BASH_PROCESS_SUBST
+ if (style == PSUB)
+ USTPUTC(c == '<' ? CTLFROMPROC : CTLTOPROC, out);
+ else
+#endif
+ USTPUTC(CTLBACKQ, out);
if (oldstyle)
goto parsebackq_oldreturn;
+#if BASH_PROCESS_SUBST
+ else if (style == PSUB)
+ goto parsebackq_psreturn;
+#endif
goto parsebackq_newreturn;
}
@@ -13334,6 +13457,9 @@ cmdloop(int top)
#if JOBS
if (doing_jobctl)
showjobs(SHOW_CHANGED|SHOW_STDERR);
+#endif
+#if BASH_PROCESS_SUBST
+ unwindredir(NULL);
#endif
inter = 0;
if (iflag && top) {
diff --git a/shell/ash_test/ash-psubst/bash_procsub.right b/shell/ash_test/ash-psubst/bash_procsub.right
new file mode 100644
index 000000000..aa16a96be
--- /dev/null
+++ b/shell/ash_test/ash-psubst/bash_procsub.right
@@ -0,0 +1,9 @@
+hello 1
+hello 2
+hello 3
+<(echo "hello 0")
+hello 4
+HI THERE
+hello error
+hello error
+hello stderr
diff --git a/shell/ash_test/ash-psubst/bash_procsub.tests b/shell/ash_test/ash-psubst/bash_procsub.tests
new file mode 100755
index 000000000..63b836782
--- /dev/null
+++ b/shell/ash_test/ash-psubst/bash_procsub.tests
@@ -0,0 +1,33 @@
+# simplest case
+cat <(echo "hello 1")
+
+# can have more than one
+cat <(echo "hello 2") <(echo "hello 3")
+
+# doesn't work in quotes
+echo "<(echo \"hello 0\")"
+
+# process substitution can be nested inside command substitution
+echo $(cat <(echo "hello 4"))
+
+# example from http://wiki.bash-hackers.org/syntax/expansion/proc_subst
+# process substitutions can be passed to a function as parameters or
+# variables
+f() {
+ cat "$1" >"$x"
+}
+x=>(tr '[:lower:]' '[:upper:]') f <(echo 'hi there')
+
+# process substitution can be combined with redirection on exec
+rm -f err
+# save stderr
+exec 4>&2
+# copy stderr to a file
+exec 2> >(tee err)
+echo "hello error" >&2
+sync
+# restore stderr
+exec 2>&4
+cat err
+rm -f err
+echo "hello stderr" >&2
--
2.26.2
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