Initial revision

sudo_realpath.c

@@ -0,0 +1,189 @@
+/*
+ *  CU sudo version 1.3.1
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 1, or (at your option)
+ *  any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program; if not, write to the Free Software
+ *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ *
+ *  Please send bugs, changes, problems to sudo-bugs.cs.colorado.edu
+ *
+ *******************************************************************
+ *
+ *  This module contains realpath(3) for those systems that lack it.
+ *  realpath(3) takes a path to qualify and a pointer to a string
+ *  as a copyout parameter.  This string should be of size MAXPATHLEN.
+ *
+ *  Todd C. Miller (millert@colorado.edu) Fri Jun  3 18:32:19 MDT 1994
+ */
+
+#ifndef lint
+static char rcsid[] = "$Id$";
+#endif /* lint */
+
+#include "config.h"
+
+#include <stdio.h>
+#ifdef HAVE_UNISTD_H
+#include <unistd.h>
+#endif /* HAVE_UNISTD_H */
+#ifdef HAVE_STRING_H
+#include <string.h>
+#endif /* HAVE_STRING_H */
+#ifdef HAVE_STRINGS_H
+#include <strings.h>
+#endif /* HAVE_STRINGS_H */
+#include <errno.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <sys/param.h>
+
+#ifndef STDC_HEADERS
+extern char *strcpy();
+extern int readlink();
+extern int lstat();
+#endif /* !STDC_HEADERS */
+
+
+/*
+ * Posix versions for those without
+ */
+#ifndef _S_IFMT
+#define _S_IFMT		S_IFMT
+#endif /* _S_IFMT */
+#ifndef _S_IFLNK
+#define _S_IFLNK	S_IFLNK
+#endif /* _S_IFLNK */
+
+
+/*
+ * Prototypes
+ */
+static char * realpath_ret(char *, FILE *);
+
+
+/******************************************************************
+ *
+ *  realpath()
+ *
+ *  this function takes a path and makes it fully qualified and resolves
+ *  all symbolic links, returning the fully qualfied path.
+ */
+
+char * realpath(old, new)
+    const char * old;
+          char * new;
+{
+    char buf[MAXPATHLEN];			/* generic path buffer */
+    FILE * cwd;					/* current working dir */
+    struct stat statbuf;			/* for lstat() */
+    char * temp;				/* temporary ptr */
+    int len;					/* length parameter */
+
+    /* check for brain damage */
+    if (old == NULL || old[0] == NULL)
+	return(NULL);
+
+    /* save old cwd so we can get back */
+    if (!(cwd = fopen(".", "r")))
+	return(NULL);
+
+    new[MAXPATHLEN - 1] = '\0';
+    (void) strncpy(new, old, MAXPATHLEN - 1);
+
+    /*
+     * Resolve the last component of the path if it is a link
+     * until it is a non-link.
+     */
+    while ((statbuf.st_mode & _S_IFMT) == _S_IFLNK) {
+	/* it's a link */
+
+	if ((len = readlink(new, buf, sizeof(buf))) <= 0)
+	    return(realpath_ret(NULL, cwd));
+	buf[len] = '\0';
+
+	/*
+	 * If the link is absolute, copy it in, else remove the last
+	 * component in new and append the link unless the sum is too long.
+	 */
+	if (buf[0] == '/') {
+	    (void) strcpy(new, buf);
+	} else {
+	    if ((temp = strrchr(new, '/')))
+		*(++temp) = '\0';
+
+	    if (strlen(new) + strlen(buf) >= MAXPATHLEN ) {
+		errno = ENAMETOOLONG;
+		return(realpath_ret(NULL, cwd));
+	    }
+
+	    (void) strcat(new, buf);
+	}
+    }
+
+    /*
+     * separate the last component from the rest of the path
+     * so we can do a getcwd() safely.
+     */
+    if (!(temp = strrchr(new, '/'))) {
+	/* this should not happen */
+	errno = ENOTDIR;
+	return(realpath_ret(NULL, cwd));
+    }
+    *(temp++) = '\0';
+    (void) strcpy(buf, temp);
+
+    /*
+     * chdir() to new and go a getcwd() to find real path
+     * then append buf (last component of the path) and return.
+     */
+    if (chdir(new))
+	return(realpath_ret(NULL, cwd));
+
+    if (!(getcwd(new, MAXPATHLEN)))
+	return(realpath_ret(NULL, cwd));
+
+    /* append "/" and buf to new but watch for double '/' */
+    len = strlen(new);
+    if (len) {
+	temp = new + len;
+	if (*temp != '/') {
+	    *(++temp) = '/';
+	    *(++temp) = '\0';
+	}
+
+    }
+    (void) strcat(new, buf);
+
+    return(realpath_ret(new, cwd));
+}
+
+
+/******************************************************************
+ *
+ *  realpath_ret()
+ *
+ *  this function cd's to cwd, closes it, and returns path.
+ */
+
+static char * realpath_ret(path, cwd)
+    char * path;
+    FILE * cwd;
+{
+    int old_errno = errno;			/* so we can restore errno... */
+
+    (void) fchdir(cwd);
+    (void) fclose(cwd);
+
+    errno = old_errno;
+    return(path);
+}