Commit Graph

135 Commits

Author SHA1 Message Date
Jilles Tjoelker
4d34663be3 sh: Allow arbitrarily large numbers in break and continue.
The argument is capped to loopnest, so strtol()'s [ERANGE] can be ignored.
2014-07-20 20:29:09 +00:00
Jilles Tjoelker
d1670d4228 sh: Split set -x output into a separate function. 2013-12-06 22:24:37 +00:00
Jilles Tjoelker
2935c4cc5e sh: Make return return from the closest function or dot script.
Formerly, return always returned from a function if it was called from a
function, even if there was a closer dot script. This was for compatibility
with the Bourne shell which only allowed returning from functions.

Other modern shells and POSIX return from the function or the dot script,
whichever is closest.

Git 1.8.4's rebase --continue depends on the POSIX behaviour.

Reported by:	Christoph Mallon, avg
2013-09-04 22:10:16 +00:00
Jilles Tjoelker
9bb8ccd642 sh: Remove unnecessary reset functions.
These are already handled by exception handlers.
2013-08-16 20:24:41 +00:00
Jilles Tjoelker
0bdd387178 sh: Remove #define MKINIT.
MKINIT only served for the removed mkinit. Many variables can be static now.
2013-07-25 19:48:15 +00:00
Jilles Tjoelker
338b821b0f sh: Remove mkinit.
Replace the RESET blocks with regular functions and a reset() function that
calls them all.

This code generation tool is unusual and does not appear to provide much
benefit. I do not think isolating the knowledge about which modules need to
be reset is worth an almost 500-line build tool and wider scope for
variables used by the reset functions.

Also, relying on reset functions is often wrong: the cleanup should be done
in exception handlers so that no stale state remains after 'command eval'
and the like.
2013-07-25 15:08:41 +00:00
Jilles Tjoelker
42580a3efa sh: Do not close(-1) if pipe() fails. 2013-06-28 21:47:08 +00:00
Jilles Tjoelker
6e0f89a4b4 sh: Don't modify exit status when break/continue/return passes !.
This matches what would happen if  ! P  were to be replaced with
if P; then false; else true; fi.

Example:
  f() { ! return 0; }; f
2013-04-12 15:19:35 +00:00
Jilles Tjoelker
25e0f0f577 sh: If a SIGINT or SIGQUIT interrupts "wait", return status 128+sig. 2013-02-23 22:50:57 +00:00
Jilles Tjoelker
e9e9223546 sh: Fix a crash with the stackmark code.
If a stack mark is set while the current stack block is empty, the stack
block may move later on (because of realloc()) and the stack mark needs to
be updated. This updating does not happen after popstackmark() has been
called; therefore, call setstackmark() again if the stack mark is still
being used.

For some reason, this only affects a few users. I cannot reproduce it. The
situation seems quite rare as well because an empty stack block would
usually be freed (by popstackmark()) before execution reaches a
setstackmark() call.

PR:		175922
Tested by:	KT Sin
2013-02-19 23:46:51 +00:00
Jilles Tjoelker
4dc6bdd3e7 sh: Expand here documents in the current process.
Expand here documents at the same point other redirections are expanded but
use a non-fork subshell environment (like simple command substitutions) for
compatibility. Substitition errors result in an empty here document like
before.

As a result, a fork is avoided for short (<4K) expanded here documents.

Unexpanded here documents (with quoted end marker after <<) are not affected
by this change. They already only forked when >4K.

Side effects:
* Order of expansion is slightly different.
* Slow expansions are not executed in parallel with the redirected command.
* A non-fork subshell environment is subtly different from a forked process.
2013-02-03 15:54:57 +00:00
Jilles Tjoelker
84edde8b1a sh: Move some stackmarks to fix high memory usage in some loops.
If a loop contained certain commands (such as redirected compound commands),
the temporary memory for the redirection was not freed between iterations of
the loop but only after the loop.

Put a stackmark in evaltree(), freeing memory whenever a node has been
evaluated. Some other stackmarks are then redundant; remove them.

Example:
  while :; do { :; } </dev/null; done
2013-01-20 21:28:05 +00:00
Jilles Tjoelker
925420d09c sh: Pass $? to command substitution containing compound/multiple commands.
Example:
  false; echo $(echo $?; :)
2013-01-14 12:20:55 +00:00
Jilles Tjoelker
d6d66cfc00 sh: Detect and flag write errors on stdout in builtins.
If there is a write error on stdout, a message will be printed (to stderr)
and the exit status will be changed to 2 if it would have been 0 or 1.

PR:		bin/158206
2012-12-12 22:01:10 +00:00
Jilles Tjoelker
7cbda73825 sh: Prefer internal nextopt() to libc getopt().
This reduces code duplication and code size.

/usr/bin/printf is not affected.

Side effect: different error messages when certain builtins are passed
invalid options.
2012-09-15 21:56:30 +00:00
Jilles Tjoelker
84fbdd8ca0 sh: Expand assignment-like words specially for export/readonly/local.
Examples:
  export x=~
now expands the tilde
  local y=$1
is now safe, even if $1 contains IFS characters or metacharacters.

For a word to "look like an assignment", it must start with a name followed
by an equals sign, none of which may be quoted.

The special treatment applies when the first word (potentially after
"command") is "export", "readonly" or "local". There may be quoting
characters but no expansions. If "local" is overridden with a function there
is no special treatment ("export" and "readonly" cannot be overridden with a
function).

If things like
  local arr=(1 2 3)
are ever allowed in the future, they cannot call a "local" function. This
would either be a run-time error or it would call the builtin.

This matches Austin Group bug #351, planned for the next issue of POSIX.1.

PR:		bin/166771
2012-07-15 10:19:43 +00:00
Jilles Tjoelker
caf29fab8c sh: Use vfork in a few common cases.
This uses vfork() for simple commands and command substitutions containing a
single simple command, invoking an external program under certain conditions
(no redirections or variable assignments, non-interactive shell, no job
control). These restrictions limit the amount of code executed in a vforked
child.

There is a large speedup (for example 35%) in microbenchmarks. The
difference in buildkernel is smaller (for example 0.5%) but still
statistically significant. See
http://lists.freebsd.org/pipermail/freebsd-hackers/2012-January/037581.html
for some numbers.

The use of vfork() can be disabled by setting a variable named
SH_DISABLE_VFORK.
2012-02-04 23:12:14 +00:00
Jilles Tjoelker
6eff4a75d5 sh: Fix $? in the first command of a 'for'.
In the first command of a 'for', $? should be the exit status of the last
pipeline (command substitution in the word list or command before 'for'),
not always 0.
2012-01-22 14:00:33 +00:00
Jean-Sébastien Pédron
01a43bcf7b sh: Fix execution of multiple statements in a trap when evalskip is set
Before this fix, only the first statement of the trap was executed if
evalskip was set. This is for example the case when:
    o  "-e" is set for this shell
    o  a trap is set on EXIT
    o  a function returns 1 and causes the script to abort

Reviewed by:	jilles
MFC after:	2 weeks
2012-01-16 11:07:46 +00:00
Jilles Tjoelker
93fcb2511b sh: Fix some bugs with exit status from case containing ;&.
Also, rework evalcase() to not evaluate any tree. Instead, return the
NCLISTFALLTHRU node and handle it in evaltree().

Fixed bugs:

* If a ;& list with non-zero exit status is followed by an empty ;; or final
  list, the exit status of the case command should be equal to the exit
  status of the ;& list, not 0.

* An empty ;& case should not reset $?.
2012-01-15 21:39:38 +00:00
Jilles Tjoelker
92371efca2 sh: Fix two bugs with case and exit status:
* If no pattern is matched, POSIX says the exit status shall be 0 (even if
  there are command substitutions).
* If a pattern is matched and there are no command substitutions, the first
  command should see the $? from before the case command, not always 0.
2012-01-15 20:04:05 +00:00
Jilles Tjoelker
a82f5687bf sh: Do not force special builtins non-special in optimized command subst.
This is not necessary: errors are already caught in evalbackcmd() and
forcelocal handles changes to variables.

Note that this depends on r223024.

MFC after:	4 weeks
2011-12-28 22:10:12 +00:00
Jilles Tjoelker
03f33e912d sh: Remove impossible evalskip check in 'for'. 2011-11-27 00:09:59 +00:00
Jilles Tjoelker
a157dc4d90 sh: Reduce one level of evaltree() recursion when executing 'case'.
Free expanded case text before executing commands.
Remove impossible evalskip checks (expanding an argument cannot set
evalskip anymore since $(break) and the like are properly executed in a
subshell environment).
2011-11-26 23:28:31 +00:00
Jilles Tjoelker
47e5204ee3 sh: Remove special support for background simple commands.
It expands the arguments in the parent shell process, which is incorrect.
2011-06-18 23:58:59 +00:00
Jilles Tjoelker
c9afaa6389 sh: Add case statement fallthrough (with ';&' instead of ';;').
Replacing ;; with the new control operator ;& will cause the next list to be
executed as well without checking its pattern, continuing until a list ends
with ;; or until the end of the case statement. This is like omitting
"break" in a C "switch" statement.

The sequence ;& was formerly invalid.

This feature is proposed for the next POSIX issue in Austin Group issue
#449.
2011-06-17 13:03:49 +00:00
Jilles Tjoelker
c5aef5377c sh: Reduce unnecessary forks with eval.
The eval special builtin now runs the code with EV_EXIT if it was run
with EV_EXIT itself.

In particular, this eliminates one fork when a command substitution contains
an eval command that ends with an external program or a subshell.

This is similar to what r220978 did for functions.
2011-06-16 21:50:28 +00:00
Jilles Tjoelker
c543e1ae9e sh: Save/restore changed variables in optimized command substitution.
In optimized command substitution, save and restore any variables changed by
expansions (${var=value} and $((var=assigned))), instead of trying to
determine if an expansion may cause such changes.

If $! is referenced in optimized command substitution, do not cause jobs to
be remembered longer.

This fixes $(jobs $!) again, simplifies the man page and shortens the code.
2011-06-12 23:06:04 +00:00
Jilles Tjoelker
292e667663 sh: Do parameter expansion before printing PS4 (set -x).
The function name expandstr() and the general idea of doing this kind of
expansion by treating the text as a here document without end marker is from
dash.

All variants of parameter expansion and arithmetic expansion also work (the
latter is not required by POSIX but it does not take extra code and many
other shells also allow it).

Command substitution is prevented because I think it causes too much code to
be re-entered (for example creating an unbounded recursion of trace lines).

Unfortunately, our LINENO is somewhat crude, otherwise PS4='$LINENO+ ' would
be quite useful.
2011-06-09 23:12:23 +00:00
Jilles Tjoelker
b3f892d9e0 sh: Fix $? in heredocs on simple commands.
PR:		bin/41410
2011-06-05 14:13:15 +00:00
Jilles Tjoelker
9338c85c31 sh: Honour -n while processing -c string. 2011-06-04 11:28:42 +00:00
Jilles Tjoelker
05a447d0b9 sh: Expand aliases after assignments and redirections. 2011-05-21 22:03:06 +00:00
Jilles Tjoelker
e64a11e9eb sh: Avoid close(-1) when evaluating a multi-command pipeline.
Valgrind complains about this.
2011-05-15 17:00:43 +00:00
Jilles Tjoelker
03b3a844d0 sh: Set $? to 0 for background commands.
For backgrounded pipelines and subshells, the previous value of $? was being
preserved, which is incorrect.

For backgrounded simple commands containing a command substitution, the
status of the last command substitution was returned instead of 0.

If fork() fails, this is an error.
2011-04-25 20:54:12 +00:00
Jilles Tjoelker
45496405c6 sh: Allow EV_EXIT through function calls, make {...} <redir more consistent.
If EV_EXIT causes an exit, use the exception mechanism to unwind
redirections and local variables. This way, if the final command is a
redirected command, an EXIT trap now executes without the redirections.

Because of these changes, EV_EXIT can now be inherited by the body of a
function, so do so. This means that a function no longer prevents a fork
before an exec being skipped, such as in
  f() { head -1 /etc/passwd; }; echo $(f)

Wrapping a single builtin in a function may still cause an otherwise
unnecessary fork with command substitution, however.

An exit command or -e failure still invokes the EXIT trap with the
original redirections and local variables in place.

Note: this depends on SHELLPROC being gone. A SHELLPROC depended on
keeping the redirections and local variables and only cleaning up the
state to restore them.
2011-04-23 22:28:56 +00:00
Jilles Tjoelker
c059d82290 sh: Remove clearcmdentry()'s now unused argument. 2011-02-05 14:08:51 +00:00
Jilles Tjoelker
3835f47c7e sh: Remove special code for shell scripts without magic number.
These are called "shell procedures" in the source.

If execve() failed with [ENOEXEC], the shell would reinitialize itself
and execute the program as a script. This requires a fair amount of code
which is not frequently used (most scripts have a #! magic number).
Therefore just execute a new instance of sh (_PATH_BSHELL) to run the
script.
2011-02-04 22:47:55 +00:00
Jilles Tjoelker
e23a66ac83 sh: Do not call exitshell() from evalcommand() unless evalcommand() forked
itself.

This ensures that certain traps caused by builtins are executed.
2011-01-05 23:17:29 +00:00
Jilles Tjoelker
850460c0f1 sh: Check readonly status for assignments on regular builtins.
An error message is written, the builtin is not executed, nonzero exit
status is returned but the shell does not abort.

This was already checked for special builtins and external commands, with
the same consequences except that the shell aborts for special builtins.

Obtained from:	NetBSD
2011-01-01 13:26:18 +00:00
Jilles Tjoelker
11535bdf04 sh: Avoid side effects from builtins in optimized command substitution.
Change the criterion for builtins to be safe to execute in the same process
in optimized command substitution from a blacklist of only cd, . and eval to
a whitelist.

This avoids clobbering the main shell environment such as by $(exit 4) and
$(set -x).

The builtins jobid, jobs, times and trap can still show information not
available in a child process; this is deliberately permitted. (Changing
traps is not.)

For some builtins, whether they are safe depends on the arguments passed to
them. Some of these are always considered unsafe to keep things simple; this
only harms efficiency a little in the rare case they are used alone in a
command substitution.
2010-12-30 22:33:55 +00:00
Jilles Tjoelker
acd7984f96 sh: Don't do optimized command substitution if expansions have side effects.
Before considering to execute a command substitution in the same process,
check if any of the expansions may have a side effect; if so, execute it in
a new process just like happens if it is not a single simple command.

Although the check happens at run time, it is a static check that does not
depend on current state. It is triggered by:
- expanding $! (which may cause the job to be remembered)
- ${var=value} default value assignment
- assignment operators in arithmetic
- parameter substitutions in arithmetic except ${#param}, $$, $# and $?
- command substitutions in arithmetic

This means that $((v+1)) does not prevent optimized command substitution,
whereas $(($v+1)) does, because $v might expand to something containing
assignment operators.

Scripts should not depend on these exact details for correctness. It is also
imaginable to have the shell fork if and when a side effect is encountered
or to create a new temporary namespace for variables.

Due to the $! change, the construct $(jobs $!) no longer works. The value of
$! should be stored in a variable outside command substitution first.
2010-12-28 21:27:08 +00:00
Jilles Tjoelker
45b71cd16e sh: Make expansion errors in optimized command substitution non-fatal.
Command substitutions consisting of a single simple command are executed in
the main shell process but this should be invisible apart from performance
and very few exceptions such as $(trap).
2010-12-28 13:28:24 +00:00
Jilles Tjoelker
9d37e15722 sh: Code size optimizations to "stack string" memory allocation:
* Prefer one CHECKSTRSPACE with multiple USTPUTC to multiple STPUTC.
* Add STPUTS macro (based on function) and use it instead of loops that add
  nul-terminated strings to the stack string.

No functional change is intended, but code size is about 1K less on i386.
2010-11-23 22:17:39 +00:00
Jilles Tjoelker
aeb5d06504 sh: Code size optimizations to buffered output.
This is mainly less use of the outc macro.

No functional change is intended, but code size is about 2K less on i386.
2010-11-20 14:14:52 +00:00
Jilles Tjoelker
4c4164f9a7 sh: Reindent evaltree(). 2010-10-31 12:08:16 +00:00
Jilles Tjoelker
dca867f1c9 sh: Use iteration instead of recursion to evaluate semicolon lists.
This reduces CPU and memory usage when executing long lists (such
as long functions).
2010-10-31 12:06:02 +00:00
Jilles Tjoelker
274110df0a sh: Tweak some string constants to reduce code size.
* Reduce some needless differences.
* Shorten some error messages that should not happen.
2010-10-29 21:44:43 +00:00
David E. O'Brien
8832864298 In the spirit of r90111, depend on c89 and remove the "STATIC" macro
and its usage.
2010-10-13 22:18:03 +00:00
David E. O'Brien
aa7b6f8259 Consistently use "STATIC" for all functions in order to be able to set
breakpoints with in a debugger.  And use naked "static" for variables.

Noticed by:	bde
2010-10-13 04:01:01 +00:00
Jilles Tjoelker
8f2dc7de67 sh: Fix exit status if return is used within a loop condition. 2010-09-11 15:07:40 +00:00