3 files changed, 252 insertions, 2 deletions
diff --git a/common/Makefile.am b/common/Makefile.am
index 1120b07..df90b8e 100644
--- a/common/Makefile.am
+++ b/common/Makefile.am
@@ -1,6 +1,6 @@
 # Makefile.am - use automake to generate Makefile.in
 #
-# Copyright (C) 2007, 2008 Arthur de Jong
+# Copyright (C) 2007, 2008, 2009 Arthur de Jong
 #
 # This library is free software; you can redistribute it and/or
 # modify it under the terms of the GNU Lesser General Public
@@ -17,7 +17,7 @@
 # Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
 # 02110-1301 USA
 
-noinst_LIBRARIES = libtio.a libprot.a libdict.a
+noinst_LIBRARIES = libtio.a libprot.a libdict.a libexpr.a
 
 AM_CPPFLAGS=-I$(top_srcdir)
 AM_CFLAGS = -fPIC
@@ -28,3 +28,5 @@ libprot_a_SOURCES = nslcd-prot.c nslcd-prot.h
 
 libdict_a_SOURCES = dict.c dict.h \
                     set.c set.h
+
+libexpr_a_SOURCES = expr.c expr.h
diff --git a/common/expr.c b/common/expr.c
new file mode 100644
index 0000000..679d8b7
--- /dev/null
+++ b/common/expr.c
@@ -0,0 +1,207 @@
+/*
+   expr.c - limited shell-like expression parsing functions
+   This file is part of the nss-pam-ldapd library.
+
+   Copyright (C) 2009 Arthur de Jong
+
+   This library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   This library 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
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with this library; if not, write to the Free Software
+   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+   02110-1301 USA
+*/
+
+#include "config.h"
+
+#include <stdlib.h>
+#include <string.h>
+
+#include "expr.h"
+
+/* the maximum length of a variable name */
+#define MAXVARLENGTH 30
+
+static inline int my_isalpha(const char c)
+{
+  return ((c>='a')&&(c<='z'))||((c>='A')&&(c<='Z'));
+}
+
+static inline int my_isalphanum(const char c)
+{
+  return my_isalpha(c)||((c>='0')&&(c<='9'));
+}
+
+#include <stdio.h>
+
+/* return the part of the string that is a valid name */
+MUST_USE static const char *parse_name(const char *str,int *ptr,char *buffer,size_t buflen)
+{
+  int i=0;
+  /* clear the buffer */
+  buffer[i]='\0';
+  /* look for an alpha+alphanumeric* string */
+  if (!my_isalpha(str[*ptr]))
+    return NULL;
+  while (my_isalphanum(str[*ptr]))
+  {
+    if ((size_t)i>=buflen)
+      return NULL;
+    buffer[i++]=str[(*ptr)++];
+  }
+  /* NULL-terminate the string */
+  if ((size_t)i>=buflen)
+    return NULL;
+  buffer[i++]='\0';
+  return buffer;
+}
+
+/* definition of the parse functions (they call eachother) */
+MUST_USE static const char *parse_dollar_expression(
+              const char *str,int *ptr,char *buffer,size_t buflen,
+              expander_t expander,void *expander_arg);
+MUST_USE static const char *parse_expression(
+              const char *str,int *ptr,int endat,char *buffer,size_t buflen,
+              expander_t expander,void *expander_arg);
+
+MUST_USE static const char *parse_dollar_expression(
+              const char *str,int *ptr,char *buffer,size_t buflen,
+              expander_t expander,void *expander_arg)
+{
+  char varname[MAXVARLENGTH];
+  const char *varvalue;
+  if ((buflen<=0)||(buffer==NULL)||(str==NULL)||(ptr==NULL))
+    return NULL;
+  if (str[*ptr]=='{')
+  {
+    (*ptr)++;
+    /* the first part is always a variable name */
+    if (parse_name(str,ptr,varname,sizeof(varname))==NULL)
+      return NULL;
+    varvalue=expander(varname,expander_arg);
+    if (str[*ptr]=='}')
+    {
+      /* simple substitute */
+      if (strlen(varvalue)>=buflen)
+        return NULL;
+      strcpy(buffer,varvalue);
+    }
+    else if (strncmp(str+*ptr,":-",2)==0)
+    {
+      /* if variable is not set or empty, substitute remainder */
+      (*ptr)+=2;
+      if (parse_expression(str,ptr,'}',buffer,buflen,expander,expander_arg)==NULL)
+        return NULL;
+      if ((varvalue!=NULL)&&(*varvalue!='\0'))
+      {
+        if (strlen(varvalue)>=buflen)
+          return NULL;
+        strcpy(buffer,varvalue);
+      }
+    }
+    else if (strncmp(str+*ptr,":+",2)==0)
+    {
+      /* if variable is set, substitute remainer */
+      (*ptr)+=2;
+      if (parse_expression(str,ptr,'}',buffer,buflen,expander,expander_arg)==NULL)
+        return NULL;
+      if ((varvalue==NULL)||(*varvalue=='\0'))
+        buffer[0]='\0';
+    }
+    else
+      return NULL;
+    (*ptr)++; /* skip closing } */
+  }
+  else
+  {
+    /* it is a simple reference to a variable, like $uidNumber */
+    if (parse_name(str,ptr,varname,sizeof(varname))==NULL)
+      return NULL;
+    varvalue=expander(varname,expander_arg);
+    if (strlen(varvalue)>=buflen)
+      return NULL;
+    strcpy(buffer,varvalue);
+  }
+  return buffer;
+}
+
+MUST_USE static const char *parse_expression(
+              const char *str,int *ptr,int endat,char *buffer,size_t buflen,
+              expander_t expander,void *expander_arg)
+{
+  int j=0;
+  /* go over string */
+  while ((str[*ptr]!=endat)&&(str[*ptr]!='\0'))
+  {
+    switch (str[*ptr])
+    {
+      case '$': /* beginning of an expression */
+        (*ptr)++;
+        if ((size_t)j>=buflen)
+          return NULL;
+        if (parse_dollar_expression(str,ptr,buffer+j,buflen-j,expander,expander_arg)==NULL)
+          return NULL;
+        j=strlen(buffer);
+        break;
+      case '\\': /* escaped character, unescape */
+        (*ptr)++;
+      default: /* just copy the text */
+        if ((size_t)j>=buflen)
+          return NULL;
+        buffer[j++]=str[*ptr];
+        (*ptr)++;
+    }
+  }
+  /* NULL-terminate buffer */
+  if ((size_t)j>=buflen)
+    return NULL;
+  buffer[j++]='\0';
+  return buffer;
+}
+
+MUST_USE const char *expr_parse(const char *str,char *buffer,size_t buflen,
+                                expander_t expander,void *expander_arg)
+
+{
+  int i=0;
+  return parse_expression(str,&i,'\0',buffer,buflen,expander,expander_arg);
+}
+
+SET *expr_vars(const char *str,SET *set)
+{
+  char varname[MAXVARLENGTH];
+  int i=0;
+  /* allocate set if needed */
+  if (set==NULL)
+    set=set_new();
+  if (set==NULL)
+    return NULL;
+  /* go over string */
+  while (str[i]!='\0')
+  {
+    switch (str[i])
+    {
+      case '$': /* beginning of a $-expression */
+        i++;
+        if (str[i]=='{')
+          i++;
+        /* the rest should start with a variable name */
+        if (parse_name(str,&i,varname,sizeof(varname))!=NULL)
+          set_add(set,varname);
+        break;
+      case '\\': /* escaped character, unescape */
+        i++;
+      default: /* just skip */
+        i++;
+    }
+  }
+  return set;
+}
diff --git a/common/expr.h b/common/expr.h
new file mode 100644
index 0000000..9861a49
--- /dev/null
+++ b/common/expr.h
@@ -0,0 +1,41 @@
+/*
+   expr.h - limited shell-like expression parsing functions
+   This file is part of the nss-pam-ldapd library.
+
+   Copyright (C) 2009 Arthur de Jong
+
+   This library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   This library 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
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with this library; if not, write to the Free Software
+   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+   02110-1301 USA
+*/
+
+#ifndef _EXPR_H
+#define _EXPR_H 1
+
+#include "compat/attrs.h"
+#include "common/set.h"
+
+typedef const char *(*expander_t)(const char *name,void *expander_arg);
+
+/* Parse the expression and store the result in buffer, using the
+   expander function to expand variable names to values. If the expression
+   is invalid or the result didn't fit in the buffer NULL is returned. */
+MUST_USE const char *expr_parse(const char *expr,char *buffer,size_t buflen,
+                                expander_t expander,void *expander_arg);
+
+/* Return the variable names that are used in expr. If set is NULL a new one
+   is allocated, otherwise the passed set is added to. */
+SET *expr_vars(const char *expr,SET *set);
+
+#endif /* not _EXPR_H */