4c4b02c29
Denys Vlasenko
2021-06-06
Subject
ash: save Ron's patch from oblivion
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shell/ash_remove_unnecessary_code_in_backquote_expansion.patch+135 -0
| @@ -0,0 +1,135 @@ | |
| + | From: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx> |
| + | Date: Thu, 19 Apr 2018 18:16:12 +0800 |
| + | |
| + | > ash originally had support for omitting the fork when expanding a |
| + | > builtin in backquotes. dash has gradually been removing this support, |
| + | > most recently in commit 66b614e29038e31745c4a5d296f64f8d64f5c377 |
| + | > ("[EVAL] Remove unused EV_BACKCMD flag"). |
| + | > |
| + | > Some traces still remain, however. Remove: |
| + | > |
| + | > - the buf and nleft elements of the backcmd structure; |
| + | > - a misleading comment regarding handling of builtins. |
| + | > |
| + | > Signed-off-by: Ron Yorston <rmy@xxxxxxxxxxxx> |
| + | |
| + | Unfortunately we may need this at some point in the future due |
| + | to changes in POSIX. So let's keep it around for now until we |
| + | get things such as `jobs -p` to work. |
| + | |
| + | ************************************* |
| + | |
| + | From: Ron Yorston <rmy@xxxxxxxxxxxx> |
| + | Date: Thu, 19 Apr 2018 17:18:47 +0100 |
| + | |
| + | >Unfortunately we may need this at some point in the future due |
| + | >to changes in POSIX. So let's keep it around for now until we |
| + | >get things such as `jobs -p` to work. |
| + | |
| + | As you wish. |
| + | |
| + | Something even more trivial I noticed later: the TRACE at the end of |
| + | expbackq incorrectly refers to the function as evalbackq. |
| + | |
| + | ************************************* |
| + | |
| + | Date: Tue, 10 Apr 2018 13:23:35 +0100 |
| + | From: Ron Yorston <[email protected]> |
| + | To: [email protected] |
| + | Subject: [PATCH] ash: remove unnecessary code in backquote expansion |
| + | |
| + | Some traces remain of ash's ancient support for omitting the fork when |
| + | expanding a builtin command in backquotes. |
| + | |
| + | Remove: |
| + | |
| + | - the buf and nleft elements of the backcmd structure; |
| + | - a misleading comment regarding handling of builtins. |
| + | |
| + | I've submitted a similar patch to dash. |
| + | |
| + | Signed-off-by: Ron Yorston <[email protected]> |
| + | --- |
| + | shell/ash.c | 37 +++++++++---------------------------- |
| + | 1 file changed, 9 insertions(+), 28 deletions(-) |
| + | |
| + | diff --git a/shell/ash.c b/shell/ash.c |
| + | index 45c747dbc..6f1458722 100644 |
| + | --- a/shell/ash.c |
| + | +++ b/shell/ash.c |
| + | @@ -6356,15 +6356,12 @@ exptilde(char *startp, char *p, int flags) |
| + | } |
| + | |
| + | /* |
| + | - * Execute a command inside back quotes. If it's a builtin command, we |
| + | - * want to save its output in a block obtained from malloc. Otherwise |
| + | - * we fork off a subprocess and get the output of the command via a pipe. |
| + | - * Should be called with interrupts off. |
| + | + * Execute a command inside back quotes. We fork off a subprocess and |
| + | + * get the output of the command via a pipe. Should be called with |
| + | + * interrupts off. |
| + | */ |
| + | struct backcmd { /* result of evalbackcmd */ |
| + | int fd; /* file descriptor to read from */ |
| + | - int nleft; /* number of chars in buffer */ |
| + | - char *buf; /* buffer */ |
| + | struct job *jp; /* job structure for command */ |
| + | }; |
| + | |
| + | @@ -6394,8 +6391,6 @@ evalbackcmd(union node *n, struct backcmd *result) |
| + | struct job *jp; |
| + | |
| + | result->fd = -1; |
| + | - result->buf = NULL; |
| + | - result->nleft = 0; |
| + | result->jp = NULL; |
| + | if (n == NULL) { |
| + | goto out; |
| + | @@ -6432,8 +6427,7 @@ evalbackcmd(union node *n, struct backcmd *result) |
| + | result->jp = jp; |
| + | |
| + | out: |
| + | - TRACE(("evalbackcmd done: fd=%d buf=0x%x nleft=%d jp=0x%x\n", |
| + | - result->fd, result->buf, result->nleft, result->jp)); |
| + | + TRACE(("evalbackcmd done: fd=%d jp=0x%x\n", result->fd, result->jp)); |
| + | } |
| + | |
| + | /* |
| + | @@ -6445,7 +6439,6 @@ expbackq(union node *cmd, int flag) |
| + | struct backcmd in; |
| + | int i; |
| + | char buf[128]; |
| + | - char *p; |
| + | char *dest; |
| + | int startloc; |
| + | int syntax = flag & EXP_QUOTED ? DQSYNTAX : BASESYNTAX; |
| + | @@ -6457,24 +6450,12 @@ expbackq(union node *cmd, int flag) |
| + | evalbackcmd(cmd, &in); |
| + | popstackmark(&smark); |
| + | |
| + | - p = in.buf; |
| + | - i = in.nleft; |
| + | - if (i == 0) |
| + | - goto read; |
| + | - for (;;) { |
| + | - memtodest(p, i, syntax, flag & QUOTES_ESC); |
| + | - read: |
| + | - if (in.fd < 0) |
| + | - break; |
| + | - i = nonblock_immune_read(in.fd, buf, sizeof(buf)); |
| + | - TRACE(("expbackq: read returns %d\n", i)); |
| + | - if (i <= 0) |
| + | - break; |
| + | - p = buf; |
| + | - } |
| + | - |
| + | - free(in.buf); |
| + | if (in.fd >= 0) { |
| + | + while ((i = nonblock_immune_read(in.fd, buf, sizeof(buf))) > 0) { |
| + | + TRACE(("expbackq: read returns %d\n", i)); |
| + | + memtodest(buf, i, syntax, flag & QUOTES_ESC); |
| + | + } |
| + | + |
| + | close(in.fd); |
| + | back_exitstatus = waitforjob(in.jp); |
| + | } |