Comments on the psmisc patch?

[Svante Signell <svante.signell@telia.com>]

Hi,

Attached is a patch to make psmisc-22.14 build under GNU/Hurd.

In the patch of fuser.c I rewrote the xreadlink() function, since the
code in the Alioth patch at
http://www.gnu.org/software/hurd/hurd/porting/guidelines.html 
does not work :-( 

I realize now that setting the error number is not needed for malloc and
realloc, will change that later.

Functionality is limited, since neither /proc/mounts, /proc/net/unix,
etc exists.

The last change in fuser.h, not including lists.h jumps over large parts
of the code, but since the /proc interface is only partially supported
on Hurd, not much harm is done. An example is: /proc/self/mountinfo

Build and run tested on Hurd and Linux (both __GNU__ and linux versions)

Comments are welcome!

Thanks!

diff -ur psmisc-22.14/debian/rules psmisc-22.14.modified//debian/rules
--- psmisc-22.14/debian/rules	2011-09-14 18:40:34.000000000 +0200
+++ psmisc-22.14.modified//debian/rules	2011-09-21 13:03:45.000000000 +0200
@@ -7,6 +7,6 @@
 override_dh_auto_install:
 	dh_auto_install
 	mv debian/psmisc/usr/bin/fuser debian/psmisc/bin/fuser
-	if [ "$(DEB_HOST_ARCH_OS)" = "kfreebsd" ] ; then \
+	if [ "$(DEB_HOST_ARCH_OS)" = "kfreebsd" -o "$(DEB_HOST_ARCH_OS)" = "hurd" ] ; then \
 	  rm debian/psmisc/usr/share/man/man1/peekfd.1 ; \
 	fi
diff -ur psmisc-22.14/src/fuser.c psmisc-22.14.modified//src/fuser.c
--- psmisc-22.14/src/fuser.c	2011-06-20 13:41:13.000000000 +0200
+++ psmisc-22.14.modified//src/fuser.c	2011-10-10 22:28:59.000000000 +0200
@@ -1951,10 +1951,40 @@
  * Somehow the realpath(3) glibc function call, nevertheless
  * it avoids lstat(2) system calls.
  */
+#ifndef __GNU__
 static char real[PATH_MAX+1];
+#else
+char* xreadlink(const char *filename) {
+	int nchars, size = 128;
+	char *buffer;
+	if ((buffer=(char*)malloc(size)) == NULL) {
+		errno = ENOMEM;
+		return NULL;
+	}
+	while ((nchars = readlink(filename,buffer,size)) == size) {
+		size *= 2;
+		if ((buffer = (char*)realloc(buffer,size)) == NULL) {
+			errno = ENOMEM;
+			return NULL;
+		}
+	}
+	if (nchars < 0) {
+		free (buffer);
+		errno = EINVAL;
+		return NULL;
+	}
+	buffer[nchars]='\0';
+	return buffer;
+}
+#endif
+
 char* expandpath(const char * path)
 {
+#ifndef __GNU__
 	char tmpbuf[PATH_MAX+1];
+#else
+	char *tmpbuf=NULL;
+#endif
 	const char *start, *end;
 	char *curr, *dest;
 	int deep = MAXSYMLINKS;
@@ -1962,6 +1992,7 @@
 	if (!path || *path == '\0')
 		return (char*)0;
 
+#ifndef __GNU__
 	curr = &real[0];
 
 	if (*path != '/') {
@@ -1972,6 +2003,17 @@
 		*curr = '/';
 		dest = curr + 1;
 	}
+#else
+	if (*path != '/') {
+		if ((curr = get_current_dir_name()) == NULL)
+			return (char*)0;
+		dest = rawmemchr(curr, '\0');
+	} else {
+		curr = malloc(1 + 1);
+		*curr = '/';
+		dest = curr + 1;
+	}
+#endif
 
 	for (start = end = path; *start; start = end) {
 
@@ -1990,27 +2032,37 @@
 				while ((--dest)[-1] != '/')
 					;
 		} else {
+#ifndef __GNU__
 			char lnkbuf[PATH_MAX+1];
+#else
+			char *lnkbuf = NULL;
+#endif
 			size_t len;
 			ssize_t n;
 
 			if (dest[-1] != '/')
 				*dest++ = '/';
 
+#ifndef __GNU__
 			if (dest + (end - start) > curr + PATH_MAX) {
 				errno = ENAMETOOLONG;
 				return (char*)0;
 			}
+#endif
 
 			dest = mempcpy(dest, start, end - start);
 			*dest = '\0';
 
 			if (deep-- < 0) {
 				errno = ELOOP;
+#ifdef __GNU__
+				free(curr);
+#endif
 				return (char*)0;
 			}
 
 			errno = 0;
+#ifndef __GNU__
 			if ((n = readlink(curr, lnkbuf, PATH_MAX)) < 0) {
 				deep = MAXSYMLINKS;
 				if (errno == EINVAL)
@@ -2024,6 +2076,21 @@
 				errno = ENAMETOOLONG;
 				return (char*)0;
 			}
+#else
+			lnkbuf = xreadlink(curr);
+			if (lnkbuf == NULL) {
+				deep = MAXSYMLINKS;
+				if (errno == EINVAL)
+					continue;	/* Not a symlink */
+				free(lnkbuf);
+				free(curr);
+				return (char*)0;
+			}
+
+			len = strlen(end);
+			n = strlen(lnkbuf);
+			tmpbuf = malloc(n + len + 1);
+#endif
 
 			memmove(&tmpbuf[n], end, len + 1);
 			path = end = memcpy(tmpbuf, lnkbuf, n);
@@ -2033,6 +2100,9 @@
 			else if (dest > curr + 1)
 			    while ((--dest)[-1] != '/');
 			
+#ifdef __GNU__
+	free(lnkbuf);
+#endif
 		}
 	}
 
@@ -2040,5 +2110,8 @@
 		--dest;
 	*dest = '\0';
 
+#ifdef __GNU__
+	free(tmpbuf);
+#endif
 	return curr;
 }
diff -ur psmisc-22.14/src/fuser.h psmisc-22.14.modified//src/fuser.h
--- psmisc-22.14/src/fuser.h	2011-02-09 23:53:26.000000000 +0100
+++ psmisc-22.14.modified//src/fuser.h	2011-10-04 13:54:11.000000000 +0200
@@ -86,7 +86,7 @@
 	struct mount_list *next;
 };
 
-#if defined (__GNUC__) && defined(__OPTIMIZE__)
+#if defined (__GNUC__) && defined(__OPTIMIZE__) && !defined(__GNU__)
 # include "lists.h"
 typedef struct mntinfo_s {
     list_t   this;