Relevant BUGIDs: 517064

Purpose of commit: feature

Commit summary:
---------------
document old feature and add '\]' parsing to make it a better feature.
The feature is that we can accept spaces in module arguments by enclosing
the whole argument inside square brackets. For example a module argument
like this:

  "[hello [you\], this is me]"

will be parsed as

  "hello [you], this is me"

Not very interesting, but you get the idea.
Thanks to Russell Kliese for requesting this.

3 files changed, 39 insertions, 4 deletions

diff --git a/CHANGELOG b/CHANGELOG
index 055f2b7b..dd759764 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -55,6 +55,9 @@ bug report - outstanding bugs are listed here:
 0.76: please submit patches for this section with actual code/doc
       patches!
 
+* '[...]' parsing: document it and also fix it to support '\]' escape
+  sequence. Feature request from Russell Kliese (Bug 517064 -
+  agmorgan).
 * pam_rootok: compilation warning noted by Tony den Haan wrt no
   prototype for strcmp() (Bug 557322 - agmorgan).
 * documentation: (a few of mine in passing) and app documentation
diff --git a/doc/pam_source.sgml b/doc/pam_source.sgml
index 92295126..7ed1e131 100644
--- a/doc/pam_source.sgml
+++ b/doc/pam_source.sgml
@@ -46,7 +46,7 @@ DAMAGE.
 
 <title>The Linux-PAM System Administrators' Guide
 <author>Andrew G. Morgan, <tt>morgan@kernel.org</tt>
-<date>DRAFT v0.76 2002/05/09
+<date>DRAFT v0.76 2002/05/26
 <abstract>
 This manual documents what a system-administrator needs to know about
 the <bf>Linux-PAM</bf> library. It covers the correct syntax of the
@@ -366,7 +366,7 @@ A general configuration line of the <tt>/etc/pam.conf</tt> file has
 the following form:
 <tscreen>
 <verb>
-service-name   module-type   control-flag   module-path   arguments
+service-name   module-type   control-flag   module-path   args
 </verb>
 </tscreen>
 Below, we explain the meaning of each of these tokens. The second (and
@@ -575,6 +575,26 @@ encountering an invalid argument, the module is required to write an
 error to <tt/syslog(3)/. For a list of <em/generic/ options see the
 next section.
 
+Note, if you wish to include spaces in an argument, you should
+surround that argument with square brackets. For example:
+<tscreen>
+<verb>
+squid auth required pam_mysql.so user=passwd_query passwd=mada \
+        db=eminence [query=select user_name from internet_service where \
+                     user_name='%u' and password=PASSWORD('%p') and \
+                     service='web_proxy']
+</verb>
+</tscreen>
+Note, when using this convention, you can include `<tt/[/' characters
+inside the string, and if you wish to include a `<tt/]/' character
+inside the string that will survive the argument parsing, you should
+use `<tt/\[/'. In other words:
+<tscreen>
+<verb>
+[..[..\]..]    -->   ..[..]..
+</verb>
+</tscreen>
+
 </descrip>
 
 <p>
diff --git a/libpam/pam_misc.c b/libpam/pam_misc.c
index 2d93a946..bd4ed958 100644
--- a/libpam/pam_misc.c
+++ b/libpam/pam_misc.c
@@ -43,7 +43,7 @@ char *_pam_StrTok(char *from, const char *format, char **next)
      for (i=1; i<256; table[i++] = '\0');
      for (i=0; format[i] ; table[(int)format[i++]] = 'y');
 
-     /* look for first non-blank char */
+     /* look for first non-format char */
      while (*from && table[(int)*from]) {
 	  ++from;
      }
@@ -53,10 +53,22 @@ char *_pam_StrTok(char *from, const char *format, char **next)
 	  * special case, "[...]" is considered to be a single
 	  * object.  Note, however, if one of the format[] chars is
 	  * '[' this single string will not be read correctly.
+	  * Note, any '[' inside the outer "[...]" pair will survive.
+	  * Note, the first ']' will terminate this string, but
+	  *  that "\]" will get compressed into "]". That is:
+	  *
+	  *   "[..[..\]..]..." --> "..[..].."
 	  */
-	 for (end=++from; *end && *end != ']'; ++end) {
+	 char *to;
+	 for (to=end=++from; *end && *end != ']'; ++to, ++end) {
 	     if (*end == '\\' && end[1] == ']')
 		 ++end;
+	     if (to != end) {
+		 *to = *end;
+	     }
+	 }
+	 if (to != end) {
+	     *to = '\0';
 	 }
 	 /* note, this string is stripped of its edges: "..." is what
             remains */