ash: save Ron's patch from oblivion
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
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Denys Vlasenko
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135
shell/ash_remove_unnecessary_code_in_backquote_expansion.patch
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135
shell/ash_remove_unnecessary_code_in_backquote_expansion.patch
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From: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
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Date: Thu, 19 Apr 2018 18:16:12 +0800
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> ash originally had support for omitting the fork when expanding a
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> builtin in backquotes. dash has gradually been removing this support,
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> most recently in commit 66b614e29038e31745c4a5d296f64f8d64f5c377
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> ("[EVAL] Remove unused EV_BACKCMD flag").
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>
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> Some traces still remain, however. Remove:
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>
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> - the buf and nleft elements of the backcmd structure;
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> - a misleading comment regarding handling of builtins.
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>
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> Signed-off-by: Ron Yorston <rmy@xxxxxxxxxxxx>
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Unfortunately we may need this at some point in the future due
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to changes in POSIX. So let's keep it around for now until we
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get things such as `jobs -p` to work.
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*************************************
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From: Ron Yorston <rmy@xxxxxxxxxxxx>
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Date: Thu, 19 Apr 2018 17:18:47 +0100
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>Unfortunately we may need this at some point in the future due
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>to changes in POSIX. So let's keep it around for now until we
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>get things such as `jobs -p` to work.
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As you wish.
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Something even more trivial I noticed later: the TRACE at the end of
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expbackq incorrectly refers to the function as evalbackq.
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*************************************
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Date: Tue, 10 Apr 2018 13:23:35 +0100
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From: Ron Yorston <rmy@pobox.com>
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To: busybox@busybox.net
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Subject: [PATCH] ash: remove unnecessary code in backquote expansion
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Some traces remain of ash's ancient support for omitting the fork when
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expanding a builtin command in backquotes.
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Remove:
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- the buf and nleft elements of the backcmd structure;
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- a misleading comment regarding handling of builtins.
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I've submitted a similar patch to dash.
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Signed-off-by: Ron Yorston <rmy@pobox.com>
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---
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shell/ash.c | 37 +++++++++----------------------------
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1 file changed, 9 insertions(+), 28 deletions(-)
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diff --git a/shell/ash.c b/shell/ash.c
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index 45c747dbc..6f1458722 100644
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--- a/shell/ash.c
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+++ b/shell/ash.c
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@@ -6356,15 +6356,12 @@ exptilde(char *startp, char *p, int flags)
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}
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/*
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- * Execute a command inside back quotes. If it's a builtin command, we
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- * want to save its output in a block obtained from malloc. Otherwise
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- * we fork off a subprocess and get the output of the command via a pipe.
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- * Should be called with interrupts off.
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+ * Execute a command inside back quotes. We fork off a subprocess and
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+ * get the output of the command via a pipe. Should be called with
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+ * interrupts off.
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*/
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struct backcmd { /* result of evalbackcmd */
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int fd; /* file descriptor to read from */
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- int nleft; /* number of chars in buffer */
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- char *buf; /* buffer */
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struct job *jp; /* job structure for command */
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};
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@@ -6394,8 +6391,6 @@ evalbackcmd(union node *n, struct backcmd *result)
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struct job *jp;
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result->fd = -1;
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- result->buf = NULL;
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- result->nleft = 0;
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result->jp = NULL;
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if (n == NULL) {
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goto out;
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@@ -6432,8 +6427,7 @@ evalbackcmd(union node *n, struct backcmd *result)
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result->jp = jp;
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out:
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- TRACE(("evalbackcmd done: fd=%d buf=0x%x nleft=%d jp=0x%x\n",
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- result->fd, result->buf, result->nleft, result->jp));
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+ TRACE(("evalbackcmd done: fd=%d jp=0x%x\n", result->fd, result->jp));
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}
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/*
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@@ -6445,7 +6439,6 @@ expbackq(union node *cmd, int flag)
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struct backcmd in;
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int i;
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char buf[128];
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- char *p;
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char *dest;
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int startloc;
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int syntax = flag & EXP_QUOTED ? DQSYNTAX : BASESYNTAX;
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@@ -6457,24 +6450,12 @@ expbackq(union node *cmd, int flag)
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evalbackcmd(cmd, &in);
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popstackmark(&smark);
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- p = in.buf;
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- i = in.nleft;
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- if (i == 0)
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- goto read;
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- for (;;) {
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- memtodest(p, i, syntax, flag & QUOTES_ESC);
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- read:
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- if (in.fd < 0)
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- break;
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- i = nonblock_immune_read(in.fd, buf, sizeof(buf));
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- TRACE(("expbackq: read returns %d\n", i));
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- if (i <= 0)
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- break;
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- p = buf;
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- }
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-
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- free(in.buf);
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if (in.fd >= 0) {
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+ while ((i = nonblock_immune_read(in.fd, buf, sizeof(buf))) > 0) {
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+ TRACE(("expbackq: read returns %d\n", i));
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+ memtodest(buf, i, syntax, flag & QUOTES_ESC);
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+ }
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+
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close(in.fd);
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back_exitstatus = waitforjob(in.jp);
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}
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