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Add an implementation of the POSIX wordexp() and wordfree() functions,

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which perform shell-style word expansion on strings. This is still a
little rough around the edges.

PR:		13420
This commit is contained in:
Tim J. Robbins 2002-12-26 14:34:18 +00:00
parent 56f562526c
commit faea1495bf
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=108288
3 changed files with 518 additions and 2 deletions
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5
lib/libc/gen/Makefile.inc
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@ -29,7 +29,7 @@ SRCS+= __xuname.c _pthread_stubs.c _rand48.c _spinlock_stub.c _thread_init.c \
sysconf.c sysctl.c sysctlbyname.c sysctlnametomib.c \
syslog.c telldir.c termios.c time.c times.c timezone.c ttyname.c \
ttyslot.c ualarm.c ulimit.c uname.c unvis.c usleep.c utime.c \
valloc.c vis.c wait.c wait3.c waitpid.c
valloc.c vis.c wait.c wait3.c waitpid.c wordexp.c
# machine-dependent gen sources
.if exists(${.CURDIR}/${MACHINE_ARCH}/gen/Makefile.inc)
@ -56,7 +56,7 @@ MAN+= alarm.3 arc4random.3 \
strtofflags.3 sysconf.3 sysctl.3 syslog.3 tcgetpgrp.3 \
tcsendbreak.3 tcsetattr.3 tcsetpgrp.3 time.3 times.3 timezone.3 \
ttyname.3 tzset.3 ualarm.3 ucontext.3 ulimit.3 uname.3 \
unvis.3 usleep.3 utime.3 valloc.3 vis.3
unvis.3 usleep.3 utime.3 valloc.3 vis.3 wordexp.3
MLINKS+=arc4random.3 arc4random_addrandom.3 arc4random.3 arc4random_stir.3
MLINKS+=ctermid.3 ctermid_r.3
@ -131,3 +131,4 @@ MLINKS+=ttyname.3 isatty.3 ttyname.3 ttyslot.3
MLINKS+=tzset.3 tzsetwall.3
MLINKS+=unvis.3 strunvis.3 unvis.3 strunvisx.3
MLINKS+=vis.3 strvis.3 vis.3 strvisx.3
MLINKS+=wordexp.3 wordfree.3

207
lib/libc/gen/wordexp.3 Normal file
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@ -0,0 +1,207 @@
.\"
.\" Copyright (c) 2002 Tim J. Robbins
.\" All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\" notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\" notice, this list of conditions and the following disclaimer in the
.\" documentation and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.\" $FreeBSD$
.\"
.Dd December 27, 2002
.Dt WORDEXP 3
.Os
.Sh NAME
.Nm wordexp
.Nd "perform shell-style word expansions"
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In sys/types.h
.In wordexp.h
.Ft int
.Fo wordexp
.Fa "const char * restrict words"
.Fa "wordexp_t * restrict we"
.Fa "int flags"
.Fc
.Fo wordfree
.Fa "wordexp_t *we"
.Fc
.Sh DESCRIPTION
The
.Fn wordexp
function performs shell-style word expansion on
.Fa words
and places the list of words into the
.Va we_wordv
member of
.Va we ,
and the number of words into
.Va we_wordc .
.Pp
The
.Va flags
argument is the bitwise inclusive OR of any of the following constants:
.Bl -tag -width ".Dv WRDE_SHOWERR"
.It Dv WRDE_APPEND
Append the words to those generate by a previous call to
.Fn wordexp .
.It Dv WRDE_DOOFS
As many
.Dv NULL
pointers as are specified by the
.Va we_offs
member of
.Va we
are added to the front of
.Va we_wordv .
.It Dv WRDE_NOCMD
Disallow command substitution in
.Fa words .
See the note in
.Sx BUGS
before using this.
.It Dv WRDE_REUSE
The
.Va we
argument was passed to a previous successful call to
.Fn wordexp
but has not been passed to
.Fn wordfree .
The implementation may reuse the space allocated to it.
.It Dv WRDE_SHOWERR
Do not redirect shell error messages to
.Pa /dev/null .
.It Dv WRDE_UNDEF
Report error on an attempt to expand an undefined shell variable.
.El
.Pp
The
.Vt wordexp_t
structure is defined in
.Pa wordexp.h
as:
.Bd -literal -offset indent
typedef struct {
size_t we_wordc; /* count of words matched */
char **we_wordv; /* pointer to list of words */
size_t we_offs; /* slots to reserve in we_wordv */
} wordexp_t;
.Ed
.Pp
The
.Fn wordfree
function frees the memory allocated by
.Fn wordexp .
.Sh IMPLEMENTATION NOTES
The
.Fn wordexp
function is implemented as a wrapper around the undocumented
.Ic wordexp
shell built-in command.
.Sh RETURN VALUES
The
.Fn wordexp
function returns zero if successful, otherwise it returns one of the following
error codes:
.Bl -tag -width ".Dv WRDE_NOSPACE"
.It Dv WRDE_BADCHAR
The
.Fa words
argument contains one of the following unquoted characters:
<newline>,
.Ql | ,
.Ql & ,
.Ql \&; ,
.Ql < ,
.Ql > ,
.Ql \&( ,
.Ql \&) ,
.Ql { ,
.Ql } .
.It Dv WRDE_BADVAL
An attempt was made to expand an undefined shell variable and
.Dv WRDE_UNDEF
is set in
.Fa flags .
.It Dv WRDE_CMDSUB
An attempt was made to use command substitution and
.Dv WRDE_NOCMD
is set in
.Fa flags .
.It Dv WRDE_NOSPACE
Not enough memory to store the result.
.It Dv WRDE_SYNTAX
Shell syntax error in
.Fa words .
.El
.Pp
The
.Fn wordfree
function returns no value.
.Sh ENVIRONMENT
.Bl -tag -width ".Ev IFS"
.It Ev IFS
Field separator.
.El
.Sh EXAMPLES
Invoke the editor on all
.Dq Li \&.c
files in the current directory,
and
.Pa /etc/motd
(error checking omitted):
.Bd -literal -offset indent
wordexp_t we;
wordexp("${EDITOR:-vi} *.c /etc/motd", &we, 0);
execvp(we->we_wordv[0], we->we_wordv);
.Ed
.Sh DIAGNOSTICS
Diagnostic messages from the shell are written to the standard error output
if
.Dv WRDE_SHOWERR
is set in
.Fa flags .
.Sh SEE ALSO
.Xr sh 1 ,
.Xr fnmatch 3 ,
.Xr glob 3 ,
.Xr popen 3 ,
.Xr system 3
.Sh STANDARDS
The
.Fn wordexp
and
.Fn wordfree
functions conforms to
.St -p1003.1-2001 .
.Sh BUGS
Do not pass untrusted user data to
.Fn wordexp ,
regardless of whether the
.Dv WRDE_NOCMD
flag is set.
The
.Fn wordexp
function attempts to detect input that would cause commands to be
executed before passing it to the shell
but it does not use the same parser so it may be fooled.

308
lib/libc/gen/wordexp.c Normal file
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@ -0,0 +1,308 @@
/*-
* Copyright (c) 2002 Tim J. Robbins.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include "namespace.h"
#include <sys/cdefs.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <fcntl.h>
#include <paths.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <wordexp.h>
#include "un-namespace.h"
__FBSDID("$FreeBSD$");
static int we_askshell(const char *, wordexp_t *, int);
static int we_check(const char *, int);
/*
* wordexp --
* Perform shell word expansion on `words' and place the resulting list
* of words in `we'. See wordexp(3).
*
* Specified by IEEE Std. 1003.1-2001.
*/
int
wordexp(const char * __restrict words, wordexp_t * __restrict we, int flags)
{
int error;
if (flags & WRDE_REUSE)
wordfree(we);
if ((flags & WRDE_APPEND) == 0) {
we->we_wordc = 0;
we->we_wordv = NULL;
we->we_strings = NULL;
we->we_nbytes = 0;
}
if ((error = we_check(words, flags)) != 0) {
wordfree(we);
return (error);
}
if ((error = we_askshell(words, we, flags)) != 0) {
wordfree(we);
return (error);
}
return (0);
}
/*
* we_askshell --
* Use the `wordexp' /bin/sh builtin function to do most of the work
* in expanding the word string. This function is complicated by
* memory management.
*/
static int
we_askshell(const char *words, wordexp_t *we, int flags)
{
int pdes[2]; /* Pipe to child */
char bbuf[9]; /* Buffer for byte count */
char wbuf[9]; /* Buffer for word count */
long nwords, nbytes; /* Number of words, bytes from child */
long i; /* Handy integer */
size_t sofs; /* Offset into we->we_strings */
size_t vofs; /* Offset into we->we_wordv */
pid_t pid; /* Process ID of child */
int status; /* Child exit status */
char *ifs; /* IFS env. var. */
char *np, *p; /* Handy pointers */
char *nstrings; /* Temporary for realloc() */
char **nwv; /* Temporary for realloc() */
if ((ifs = getenv("IFS")) == NULL)
ifs = " \t\n";
if (pipe(pdes) < 0)
return (WRDE_NOSPACE); /* XXX */
if ((pid = fork()) < 0) {
close(pdes[0]);
close(pdes[1]);
return (WRDE_NOSPACE); /* XXX */
}
else if (pid == 0) {
/*
* We are the child; just get /bin/sh to run the wordexp
* builtin on `words'.
*/
int devnull;
char *cmd;
close(pdes[0]);
if (dup2(pdes[1], STDOUT_FILENO) < 0)
_exit(1);
close(pdes[1]);
if (asprintf(&cmd, "wordexp%c%s\n", *ifs, words) < 0)
_exit(1);
if ((flags & WRDE_SHOWERR) == 0) {
if ((devnull = open(_PATH_DEVNULL, O_RDWR, 0666)) < 0)
_exit(1);
if (dup2(devnull, STDERR_FILENO) < 0)
_exit(1);
close(devnull);
}
execl(_PATH_BSHELL, "sh", flags & WRDE_UNDEF ? "-u" : "+u",
"-c", cmd, NULL);
_exit(1);
}
/*
* We are the parent; read the output of the shell wordexp function,
* which is a 32-bit hexadecimal word count, a 32-bit hexadecimal
* byte count (not including terminating null bytes), followed by
* the expanded words separated by nulls.
*/
close(pdes[1]);
if (read(pdes[0], wbuf, 8) != 8 || read(pdes[0], bbuf, 8) != 8) {
close(pdes[0]);
return (WRDE_NOSPACE); /* XXX */
}
wbuf[8] = bbuf[8] = '\0';
nwords = strtol(wbuf, NULL, 16);
nbytes = strtol(bbuf, NULL, 16) + nwords;
/*
* Allocate or reallocate (when flags & WRDE_APPEND) the word vector
* and string storage buffers for the expanded words we're about to
* read from the child.
*/
sofs = we->we_nbytes;
vofs = we->we_wordc;
we->we_wordc += nwords;
we->we_nbytes += nbytes;
if ((nwv = realloc(we->we_wordv, (we->we_wordc + 1 +
(flags & WRDE_DOOFS ? we->we_offs : 0)) *
sizeof(char *))) == NULL) {
close(pdes[0]);
return (WRDE_NOSPACE);
}
we->we_wordv = nwv;
if ((nstrings = realloc(we->we_strings, we->we_nbytes)) == NULL) {
close(pdes[0]);
return (WRDE_NOSPACE);
}
for (i = 0; i < vofs; i++)
if (we->we_wordv[i] != NULL)
we->we_wordv[i] += nstrings - we->we_strings;
we->we_strings = nstrings;
if (read(pdes[0], we->we_strings + sofs, nbytes) != nbytes) {
close(pdes[0]);
return (WRDE_NOSPACE); /* XXX */
}
if (waitpid(pid, &status, 0) < 0 || !WIFEXITED(status) ||
WEXITSTATUS(status) != 0) {
close(pdes[0]);
return (flags & WRDE_UNDEF ? WRDE_BADVAL : WRDE_SYNTAX);
}
close(pdes[0]);
/*
* Break the null-terminated expanded word strings out into
* the vector.
*/
if (vofs == 0 && flags & WRDE_DOOFS)
while (vofs < we->we_offs)
we->we_wordv[vofs++] = NULL;
p = we->we_strings + sofs;
while (nwords-- != 0) {
we->we_wordv[vofs++] = p;
if ((np = memchr(p, '\0', nbytes)) == NULL)
return (WRDE_NOSPACE); /* XXX */
nbytes -= np - p + 1;
p = np + 1;
}
we->we_wordv[vofs] = NULL;
return (0);
}
/*
* we_check --
* Check that the string contains none of the following unquoted
* special characters: <newline> |&;<>(){}
* or command substitutions when WRDE_NOCMD is set in flags.
*/
int
we_check(const char *words, int flags)
{
char c;
int dquote, level, quote, squote;
quote = squote = dquote = 0;
while ((c = *words++) != '\0') {
switch (c) {
case '\\':
quote ^= 1;
break;
case '\'':
if (quote + dquote == 0)
squote ^= 1;
break;
case '"':
if (quote + squote == 0)
dquote ^= 1;
break;
case '`':
if (quote + squote == 0 && flags & WRDE_NOCMD)
return (WRDE_CMDSUB);
while ((c = *words++) != '\0' && c != '`')
if (c == '\\' && (c = *words++) == '\0')
break;
if (c == '\0')
return (WRDE_SYNTAX);
break;
case '|': case '&': case ';': case '<': case '>':
case '{': case '}': case '(': case ')': case '\n':
if (quote + squote + dquote == 0)
return (WRDE_BADCHAR);
break;
case '$':
if ((c = *words++) == '\0')
break;
else if (c == '(') {
if (flags & WRDE_NOCMD)
return (WRDE_CMDSUB);
level = 1;
while ((c = *words++) != '\0') {
if (c == '\\') {
if ((c = *words++) == '\0')
break;
} else if (c == '(')
level++;
else if (c == ')' && --level == 0)
break;
}
if (c == '\0' || level != 0)
return (WRDE_SYNTAX);
} else if (c == '{') {
level = 1;
while ((c = *words++) != '\0') {
if (c == '\\') {
if ((c = *words++) == '\0')
break;
} else if (c == '{')
level++;
else if (c == '}' && --level == 0)
break;
}
if (c == '\0' || level != 0)
return (WRDE_SYNTAX);
}
break;
default:
break;
}
}
if (quote + squote + dquote != 0)
return (WRDE_SYNTAX);
return (0);
}
/*
* wordfree --
* Free the result of wordexp(). See wordexp(3).
*
* Specified by IEEE Std. 1003.1-2001.
*/
void
wordfree(wordexp_t *we)
{
if (we == NULL)
return;
free(we->we_wordv);
free(we->we_strings);
we->we_wordv = NULL;
we->we_strings = NULL;
we->we_nbytes = 0;
we->we_wordc = 0;
}