Rework usershell.c, as the old one was packed full of unhandled

failures, returned stack allocated memory, and misbehaved itself
in a number of other annoying ways,
 -Erik

libc/unistd/usershell.c

@@ -1,63 +1,134 @@
-/* vi: set sw=4 ts=4: */
-/* getusershell and friends for uClibc
+/*
+ * Copyright (c) 1985, 1993
+ *	The Regents of the University of California.  All rights reserved.
  *
- * Copyright (C) 2002 by Robert Griebl <griebl@gmx.de>
+ * 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.
+ * 4. Neither the name of the University nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
  *
- * This program is free software; you can redistribute it and/or modify it
- * under the terms of the GNU Library General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or (at your
- * option) any later version.
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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.
  *
- * 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 Library General Public License
- * for more details.
- *
- * You should have received a copy of the GNU Library General Public License
- * along with this program; if not, write to the Free Software Foundation,
- * Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ * This version has been hevily modified for use with uClibc
+ * November 2002, Erik Andersen <andersen@codepoet.org> 
  */
 
+#include <sys/param.h>
+#include <sys/file.h>
+#include <sys/stat.h>
 #include <stdio.h>
+#include <stdio_ext.h>
+#include <ctype.h>
+#include <stdlib.h>
 #include <unistd.h>
+#include <paths.h>
+
+/*
+ * Local shells should NOT be added here.  They should be added in
+ * /etc/shells.
+ */
 
-/* Rely on the .bss to zero these */
-static FILE *fp;
-static int isopen;
-static char **cursh;
-static char *validsh [] = { "/bin/sh", "/bin/csh", 0 };
+static const char * const validsh[] = { _PATH_BSHELL, _PATH_CSHELL, NULL };
+static char **curshell, **shells, *strings;
+static char **initshells __P((void));
 
-void endusershell ( void )
+/*
+ * Get a list of shells from _PATH_SHELLS, if it exists.
+ */
+char * getusershell(void)
 {
-	if ( fp && isopen )
-		fclose ( fp );
-	isopen = 0;
+    char *ret;
+
+    if (curshell == NULL)
+	curshell = initshells();
+    ret = *curshell;
+    if (ret != NULL)
+	curshell++;
+    return (ret);
 }
 
-void setusershell ( void )
+static void __free_initshell_memory(void)
 {
-	if ( isopen )
-		endusershell ( );
-	fp = fopen ( "/etc/shells", "r" );
-	cursh = validsh;
-	isopen = 1;
+    if (shells != NULL) {
+	free(shells);
+    }
+    shells = NULL;
+    if (strings != NULL) {
+	free(strings);
+    }
+    strings = NULL;
 }
 
-char *getusershell ( void )
+void endusershell(void)
 {
-	char line [BUFSIZ];
-
-	if ( !isopen )
-		setusershell ( );
+    __free_initshell_memory();
+    curshell = NULL;
+}
 
-	if ( fp ) {
-		return fgets ( line, sizeof( line ) - 1, fp );
-	} else {
-		char *result = *cursh;
+void setusershell(void)
+{
 
-		if ( result )
-			cursh++;
-		return result;  
-	}
+    curshell = initshells();
 }
 
+static char ** initshells(void)
+{
+    register char **sp, *cp;
+    register FILE *fp;
+    struct stat statb;
+    int flen;
+
+    __free_initshell_memory();
+
+    if ((fp = fopen(_PATH_SHELLS, "r")) == NULL)
+	return (char **) validsh;
+    if (fstat(fileno(fp), &statb) == -1) {
+	goto cleanup;
+    }
+    if ((strings = malloc((unsigned)statb.st_size + 1)) == NULL) {
+	goto cleanup;
+    }
+    if ((shells = calloc((unsigned)statb.st_size / 3, sizeof (char *))) == NULL) {
+	goto cleanup;
+    }
+    /* No threads using this stream.  */
+    __fsetlocking (fp, FSETLOCKING_BYCALLER);
+    sp = shells;
+    cp = strings;
+    flen = statb.st_size;
+    while (fgets_unlocked(cp, flen - (cp - strings), fp) != NULL) {
+	while (*cp != '#' && *cp != '/' && *cp != '\0')
+	    cp++;
+	if (*cp == '#' || *cp == '\0')
+	    continue;
+	*sp++ = cp;
+	while (!isspace(*cp) && *cp != '#' && *cp != '\0')
+	    cp++;
+	*cp++ = '\0';
+    }
+    *sp = NULL;
+    fclose(fp);
+    return (shells);
+
+cleanup:
+    __free_initshell_memory();
+    fclose(fp);
+    return (char **) validsh;
+}