Date: Sat, 2 Feb 2002 21:02:37 +1100 From: "Tim J. Robbins" <tim@robbins.dropbear.id.au> To: Mike Barcroft <mike@FreeBSD.ORG> Cc: freebsd-standards@FreeBSD.ORG Subject: Re: pwd -L option Message-ID: <20020202210237.A2326@descent.robbins.dropbear.id.au> In-Reply-To: <20020202032917.K10222@espresso.q9media.com>; from mike@FreeBSD.ORG on Sat, Feb 02, 2002 at 03:29:17AM -0500 References: <20020130181638.A8510@descent.robbins.dropbear.id.au> <20020202032917.K10222@espresso.q9media.com>
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Here's a new patch that I hope solves the problems you found with my
previous one. I have just a few comments, though...
On Sat, Feb 02, 2002 at 03:29:17AM -0500, Mike Barcroft wrote:
> Style bug: ANSI-style prototypes. This is a problem because the rest
> of the file uses K&R-style.
usage()'s prototype is also incorrect, then. It is:
void usage(void);
It used to have a __P() around its argument list in 4.4BSD. Even then,
the 1st ed. K&R book says nothing about "void", which is usage()'s return
type. Is the so-called K&R style that is supposed to be maintained
documented anywhere?
> Neither of these arguments are needed.
It turns out a lot of this function was not needed. It was taken straight
from NetBSD. I've trimmed it down substantially.
> > + } else if ((pt = malloc(pwdlen + 1)) == NULL)
> > + return (NULL);
> > + (void)memmove(pt, pwd, pwdlen);
> > + pt[pwdlen] = '\0';
>
> This part doesn't make much sense. We already trust the environment
> variable to be NUL terminated (see strlen() above). I recommend this
> be changed to use strdup(3).
Agreed. I don't see why dynamic allocation is needed here at all, so I've
changed it to return the value of PWD straight from the environment.
Tim
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Index: pwd/pwd.1
===================================================================
RCS file: /home/ncvs/src/bin/pwd/pwd.1,v
retrieving revision 1.15
diff -u -r1.15 pwd.1
--- pwd/pwd.1 2001/08/15 09:09:36 1.15
+++ pwd/pwd.1 2002/02/02 10:02:31
@@ -43,6 +43,7 @@
.Nd return working directory name
.Sh SYNOPSIS
.Nm
+.Op Fl LP
.Sh DESCRIPTION
.Nm Pwd
writes the absolute pathname of the current working directory to
@@ -54,17 +55,35 @@
Consult the
.Xr builtin 1
manual page.
+.Pp
+The options are as follows:
+.Bl -tag -width indent
+.It Fl L
+Display the logical current working directory.
+.It Fl P
+Display the physical current working directory (all symbolic links resolved).
+This is the default.
+.Pp
+.El
+Only one of
+.Fl L
+and
+.Fl P
+may be specified.
+.Sh ENVIRONMENT
+Environment variables used by
+.Nm :
+.Bl -tag -width PWD
+.It Ev PWD
+Logical current working directory.
.Sh DIAGNOSTICS
.Ex -std
.Sh STANDARDS
The
.Nm
utility is expected to be
-.St -p1003.2
+.St -p1003.1-2001
compatible.
-The
-.Fl L
-flag is not supported.
.Sh SEE ALSO
.Xr builtin 1 ,
.Xr cd 1 ,
@@ -80,3 +99,9 @@
However, it can give a different answer in the rare case
that the current directory or a containing directory was moved after
the shell descended into it.
+.Pp
+The
+.Fl L
+option does not work unless the
+.Ev PWD
+variable is exported by the shell.
Index: pwd/pwd.c
===================================================================
RCS file: /home/ncvs/src/bin/pwd/pwd.c,v
retrieving revision 1.14
diff -u -r1.14 pwd.c
--- pwd/pwd.c 2002/02/02 06:48:10 1.14
+++ pwd/pwd.c 2002/02/02 10:02:31
@@ -45,31 +45,38 @@
"$FreeBSD: src/bin/pwd/pwd.c,v 1.14 2002/02/02 06:48:10 imp Exp $";
#endif /* not lint */
+#include <sys/types.h>
+#include <sys/stat.h>
+
#include <err.h>
+#include <errno.h>
#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/param.h>
+extern char *__progname;
+
+static char *getcwd_logical(void);
void usage(void);
int
main(int argc, char *argv[])
{
+ int Lflag, Pflag;
int ch;
char *p;
char buf[PATH_MAX];
- /*
- * Flags for pwd are a bit strange. The POSIX 1003.2B/D9 document
- * has an optional -P flag for physical, which is what this program
- * will produce by default. The logical flag, -L, should fail, as
- * there's no way to display a logical path after forking.
- */
- while ((ch = getopt(argc, argv, "P")) != -1)
+ Lflag = Pflag = 0;
+ while ((ch = getopt(argc, argv, "LP")) != -1)
switch (ch) {
+ case 'L':
+ ++Lflag;
+ break;
case 'P':
+ ++Pflag;
break;
case '?':
default:
@@ -78,27 +85,52 @@
argc -= optind;
argv += optind;
- if (argc == 1) {
+ if (strcmp(__progname, "realpath") == 0) {
+ if (argc != 1 || Lflag || Pflag)
+ usage();
p = realpath(argv[0], buf);
if (p == NULL)
err(1, "%s", argv[0]);
(void)printf("%s\n", p);
- } else if (argc == 0) {
- p = getcwd(NULL, (size_t)0);
+ } else {
+ if (argc != 0 || (Lflag && Pflag))
+ usage();
+ p = Lflag ? getcwd_logical() : getcwd(NULL, 0);
if (p == NULL)
err(1, ".");
(void)printf("%s\n", p);
- } else {
- usage();
}
exit(0);
}
void
-usage(void)
+usage()
+{
+ if (strcmp (__progname, "realpath") == 0)
+ (void)fprintf(stderr, "usage: realpath [file ...]\n");
+ else
+ (void)fprintf(stderr, "usage: pwd [-LP]\n");
+ exit(1);
+}
+
+static char *
+getcwd_logical()
{
+ struct stat log, phy;
+ char *pwd;
+
+ /*
+ * Check that $PWD is an absolute logical pathname referring to
+ * the current working directory.
+ */
+ if ((pwd = getenv("PWD")) != NULL && *pwd == '/') {
+ if (stat(pwd, &log) == -1 || stat(".", &phy) == -1)
+ return (NULL);
+ if (log.st_dev == phy.st_dev && log.st_ino == phy.st_ino)
+ return (pwd);
+ }
- (void)fprintf(stderr, "usage: pwd\n");
- exit(1);
+ errno = ENOENT;
+ return (NULL);
}
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