ash: Expand here-documents in the current shell environment
Upstream commit:
Date: Sun, 11 Nov 2007 15:27:00 +0800
Expand here-documents in the current shell environment
Previously we always expanded here-documents in a subshell. This is
contrary to the POSIX specification and how other shells behave. What's
more this slows down many expansions due to the extra fork (however, it
must be said that it is possible for it speed up certain expansions by
running it simultaneously with the command on two CPUs).
This patch move the expansion into the current shell environment.
Test case:
unset a
cat <<- EOF > /dev/null
${a=NOT}
EOF
echo ${a}BAD
Old result:
BAD
New result:
NOTBAD
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
diff --git a/shell/ash.c b/shell/ash.c
index 5fb67c0..0134610 100644
--- a/shell/ash.c
+++ b/shell/ash.c
@@ -5444,22 +5444,29 @@
* the pipe without forking.
*/
/* openhere needs this forward reference */
-static void expandhere(union node *arg, int fd);
+static void expandhere(union node *arg);
static int
openhere(union node *redir)
{
+ char *p;
int pip[2];
size_t len = 0;
if (pipe(pip) < 0)
ash_msg_and_raise_perror("can't create pipe");
- if (redir->type == NHERE) {
- len = strlen(redir->nhere.doc->narg.text);
- if (len <= PIPE_BUF) {
- full_write(pip[1], redir->nhere.doc->narg.text, len);
- goto out;
- }
+
+ p = redir->nhere.doc->narg.text;
+ if (redir->type == NXHERE) {
+ expandhere(redir->nhere.doc);
+ p = stackblock();
}
+
+ len = strlen(p);
+ if (len <= PIPE_BUF) {
+ xwrite(pip[1], p, len);
+ goto out;
+ }
+
if (forkshell((struct job *)NULL, (union node *)NULL, FORK_NOJOB) == 0) {
/* child */
close(pip[0]);
@@ -5468,10 +5475,7 @@
ignoresig(SIGHUP); //signal(SIGHUP, SIG_IGN);
ignoresig(SIGTSTP); //signal(SIGTSTP, SIG_IGN);
signal(SIGPIPE, SIG_DFL);
- if (redir->type == NHERE)
- full_write(pip[1], redir->nhere.doc->narg.text, len);
- else /* NXHERE */
- expandhere(redir->nhere.doc, pip[1]);
+ xwrite(pip[1], p, len);
_exit(EXIT_SUCCESS);
}
out:
@@ -8016,10 +8020,9 @@
* Expand shell variables and backquotes inside a here document.
*/
static void
-expandhere(union node *arg, int fd)
+expandhere(union node *arg)
{
expandarg(arg, (struct arglist *)NULL, EXP_QUOTED);
- full_write(fd, stackblock(), expdest - (char *)stackblock());
}
/*
diff --git a/shell/ash_test/ash-heredoc/heredoc_side_effects.right b/shell/ash_test/ash-heredoc/heredoc_side_effects.right
new file mode 100644
index 0000000..53b2c03
--- /dev/null
+++ b/shell/ash_test/ash-heredoc/heredoc_side_effects.right
@@ -0,0 +1 @@
+NO BUG
diff --git a/shell/ash_test/ash-heredoc/heredoc_side_effects.tests b/shell/ash_test/ash-heredoc/heredoc_side_effects.tests
new file mode 100755
index 0000000..3fb622a
--- /dev/null
+++ b/shell/ash_test/ash-heredoc/heredoc_side_effects.tests
@@ -0,0 +1,5 @@
+unset a
+cat <<EOF >/dev/null
+${a=NO}
+EOF
+echo $a BUG
