Source Code 1992 March/Source_Code_CD-ROM_Walnut_Creek_March_1992.iso/usenet/compsrcs/misc/volume10/which4

Internet Message Format | 1991-08-27 | 8.6 KB

From decwrl!lll-winken!uunet!allbery Sun Feb 18 00:49:59 PST 1990
Article 1335 of comp.sources.misc:
Path: decwrl!lll-winken!uunet!allbery
From: [e-mail] (Maarten Litmaath)
Newsgroups: comp.sources.misc
Subject: v10i064: which4 - supersedes fast which2.c
Message-ID: <[e-mail]>
Date: 14 Feb 90 02:02:15 GMT
Sender: [e-mail]
Lines: 373
Approved: [e-mail] (Brandon S. Allbery - comp.sources.misc)

Posting-number: Volume 10, Issue 64
Submitted-by: [e-mail] (Maarten Litmaath)
Archive-name: which4

Dear moderator,
below is the latest version of which2.c, the fast form of the which(1)
command.  Besides aliases and executables, shell functions are now
recognized too.  Furthermore the output will be correct even if the
effective uid (gid) of the invoker doesn't equal the real uid (gid).

An updated manual is included.

I suggest the previous 2 versions (v04i010, v05i016) to be deleted from
the archives, or to be replaced with pointers to which4.

Thanks for your time,
                Maarten Litmaath @ VU Amsterdam:
                [e-mail], uunet!mcsun!botter!maart

: This is a shar archive.  Extract with sh, not csh.
: This archive ends with exit, so do not worry about trailing junk.
: --------------------------- cut here --------------------------
PATH=/bin:/usr/bin:/usr/ucb
echo Extracting 'which.1'
sed 's/^X//' > 'which.1' << '+ END-OF-FILE ''which.1'
X.TH WHICH 1 Sep\ 21\ 1989
X.SH NAME
Xwhich \- give alias, function or path expansion of command
X.SH SYNOPSIS
X.B which
X[
X.B \-i
X] [
X.B \-a
X] [
X.B \-\-
X] [
X.I command
X]
X.SH DESCRIPTION
X.I Which
Xprovides the user with the full expansion of the
X.I command
Xargument, be it either an \fIalias\fR, a \fIshell function\fR
Xor an executable file (default). To enable search for
X.I aliases
Xand \fIshell functions\fR
Xthe user should supply the `\fI\-i\fR'
X(= interactive) flag. In that case
X.I which
Xexpects as standard input the expansion of the \fIalias\fR
Xor \fIshell function\fR.
XIf the standard input is empty or the `\fI\-i\fR' flag has not been
Xgiven, \fIwhich\fR will try to locate \fIcommand\fR
Xin the user's \fIPATH\fR.
XThe interactive mode is easily used by setting an
X.I alias
Xlike the following:
X.ft B
X.nf
X
X    alias    which    alias !\\$ \\| /usr/local/bin/which \-i !\\*
X
X.fi
X.ft R
Xin \fIcsh\fR, or
X.ft B
X.nf
X
X    alias    which    eval alias '\\"\\$$#\\" |' \\
X            /usr/local/bin/which \-i '${1+"$@"}'
X
X.fi
X.ft R
Xin shells which are supersets of
X.I sh
Xand which know \fIaliases\fR. If your shell has \fIshell functions\fR, you
Xcan use the following function:
X.ft B
X.nf
X
X    which()
X    {
X        eval last=\\"\\$$#\\"
X        set | sed \-n "/^$last(){$/,/^}$/p" |
X            /usr/local/bin/which \-i ${1+"$@"}
X    }
X
X.fi
X.ft R
XIf the `\fI\-a\fR' (= all) flag is given,
X.I which
Xwill not stop after the first `match', but search for all occurrences of
X.I command
Xin the user's
X.I PATH.
XThe `\fI\-\-\fR'
Xflag can be used to end the list of options: the next argument (if present)
Xwill be taken as \fIcommand\fR, even if it starts with a `\-'.
X\fIWhich [\-i] [\-a] [\-\-]\fR
Xwithout further arguments prints the user's
X.I PATH
Xbroken up into its components,
Xone per line.
X.PP
XThis new version of the
X.I which
Xcommand is not a
X.I csh
Xscript.
XBeing an executable it is much faster, and not sourcing
X.I .cshrc
Xit gives a true picture of one's
X.I aliases.
X.SH EXAMPLE
X.ft B
X.nf
X% alias
Xwhich    alias !$ | /usr/local/bin/which \-i !*
X% which which
Xwhich    alias !$ | /usr/local/bin/which \-i !*
X% which \-a which
Xwhich    alias !$ | /usr/local/bin/which \-i !*
X/usr/local/bin/which
X/usr/ucb/which
X%
X.fi
X.ft R
X.SH AUTHOR
XMaarten Litmaath @ VU Informatika Amsterdam
+ END-OF-FILE which.1
chmod 'u=rw,g=r,o=r' 'which.1'
set `wc -c 'which.1'`
count=$1
case $count in
2205)    :;;
*)    echo 'Bad character count in ''which.1' >&2
        echo 'Count should be 2205' >&2
esac
echo Extracting 'Makefile'
sed 's/^X//' > 'Makefile' << '+ END-OF-FILE ''Makefile'
X# Makefile for /usr/local/bin/which
X
Xwhich:        which4.c
X        cc -O which4.c -o which
X
Xinstall:    which
X        /bin/mv -f which /usr/local/bin
X
Xdoc:
X        nroff -man which.1 > which.man
+ END-OF-FILE Makefile
chmod 'u=rw,g=r,o=r' 'Makefile'
set `wc -c 'Makefile'`
count=$1
case $count in
169)    :;;
*)    echo 'Bad character count in ''Makefile' >&2
        echo 'Count should be 169' >&2
esac
echo Extracting 'which4.c'
sed 's/^X//' > 'which4.c' << '+ END-OF-FILE ''which4.c'
X/*
X * which [-i] [-a] [--] [<command>]
X * alias which alias !\$ \| /usr/local/bin/which -i !\*
X * alias which 'eval alias \$$# | /usr/local/bin/which -i ${1+"$@"}'
X * which()
X * {
X *    eval last=\"\$$#\"
X *    set | sed -n "/^$last(){$/,/^}$/p" |
X *        /usr/local/bin/which -i ${1+"$@"}
X * }
X *
X * author: Maarten Litmaath @ VU University Amsterdam ([e-mail])
X * first change:
X *    Emile LeBlanc ([e-mail]) notes
X *    the access() system call considering everything executable for
X *    root (!), so we give root a special treatment
X *    'which', 'which -i' and 'which -a' with no further arguments now
X *    return the PATH environment variable, split up into its components
X *    the aliases defined above are slightly different from the previous
X *    version - now it's the shell who's doing the alias checking
X * second change:
X *    added support for shell functions and multiline aliases, added the
X *    `--' option, changed the source style
X * third change:
X *    to hell with access()!
X *    now stat() is used to give the right answer even if the effective
X *    uid (gid) differs from the real uid (gid)
X *    we can't use setuid(geteuid()), because that's nonportable :-(
X */
X
X#include    <sys/types.h>
X#include    <sys/stat.h>
X#include    <stdio.h>
X
X#define        BUF_SIZE    512
X#define        M_USR        0700
X#define        M_GRP        0070
X#define        M_OTH        0007
X#define        X_ALL        0111
X#define        R_ALL        0444
X
Xchar    Version[] =
X    "@(#)which 4.0 90/01/24 Maarten Litmaath @ VU Informatika Amsterdam";
Xchar    *Prog;
X
X
Xvoid    usage()
X{
X    fprintf(stderr, "Usage: %s [-i] [-a] [--] [<command>]\n", Prog);
X    exit(1);
X}
X
X
Xmain(argc, argv)
Xint    argc;
Xregister char    **argv;
X{
X    register char    *path, *s;
X    char    *save, *strcpy(), *getenv(), *fgets(), buf[BUF_SIZE];
X    int    all = 0, inter = 0, stop = 0, found = 0, uid, gid, mask,
X        xmask, rmask;
X    struct    stat    st;
X    void    usage(), convert();
X
X
X    Prog = *argv++;
X    --argc;
X
X    while (!stop && (s = *argv) && (*s == '-')) {
X        ++argv;
X        --argc;
X        ++s;
X        while (*s)
X            switch (*s++) {
X            case 'a':
X                all = 1;
X                break;
X            case 'i':
X                inter = 1;
X                break;
X            case '-':
X                stop = 1;
X                break;
X            default:
X                usage();
X            }
X    }
X
X    if (argc > 1)
X        usage();
X
X    if (inter && *argv) {
X        while (fgets(buf, sizeof buf, stdin)) {
X            if (!found) {
X                printf("%s", *argv);
X                found = 1;
X            }
X            printf("\t%s", buf);
X        }
X        if (found && !all)
X            exit(0);
X    }
X
X    if (!(save = path = getenv("PATH"))) {
X        fprintf(stderr, "%s: no PATH in environment!\n", Prog);
X        exit(1);
X    }
X
X    if (!*path)
X        save = path = ".";
X
X    if (!*argv) {
X        convert(path, buf);
X        puts(buf);
X        exit(0);
X    }
X
X    uid = geteuid();
X    gid = getegid();
X    if (uid == 0) {
X        xmask = X_ALL;
X        rmask = R_ALL;
X    }
X
X    while (*path) {
X        s = buf;
X        while ((*s++ = *path) && *path++ != ':')
X            ;
X        if (*buf == ':') {
X            /*
X             * to deal with the dubious convention that a
X             * spurious colon is equivalent to a dot...
X             */
X            *buf = '.';
X            ++s;
X        }
X        (void) strcpy(s, *argv);
X        *--s = '/';
X
X        if (stat(buf, &st) != 0 || (st.st_mode & S_IFMT) != S_IFREG)
X            continue;
X
X        /* file exists and is regular */
X
X        if (uid != 0) {
X            mask = st.st_uid == uid ? M_USR :
X                st.st_gid == gid ? M_GRP : M_OTH;
X            xmask = X_ALL & mask;
X            rmask = R_ALL & mask;
X        }
X
X        if (!(st.st_mode & xmask))
X            continue;
X
X        /* file is executable */
X
X        *s = 0;
X        if (stat(buf, &st) != 0) {
X            perror(buf);
X            continue;
X        }
X
X        if (!(st.st_mode & rmask)) {
X            fprintf(stderr,
X                "%s: %s found in unreadable directory %s!\n",
X                Prog, *argv, buf);
X            found = 1;
X            continue;
X        }
X
X        /* directory is readable */
X
X        *s = '/';
X        puts(buf);
X        if (!all)
X            exit(0);
X        found = 1;
X    }
X
X    if (found)
X        exit(0);
X
X    convert(save, buf);
X    fprintf(stderr, "%s not found in\n%s\n", *argv, buf);
X    exit(1);
X}
X
X
Xvoid    convert(path, buf)
Xregister char    *path, *buf;
X{
X    for (;;) {
X        while ((*buf++ = *path) && *path++ != ':')
X            ;
X        if (!*path)
X            break;
X        *buf++ = '\n';
X    }
X    *buf = '\0';        /* to cope with a PATH ending in ':' */
X}
+ END-OF-FILE which4.c
chmod 'u=rw,g=r,o=r' 'which4.c'
set `wc -c 'which4.c'`
count=$1
case $count in
3907)    :;;
*)    echo 'Bad character count in ''which4.c' >&2
        echo 'Count should be 3907' >&2
esac
exit 0