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/*++
/* NAME
/* mac_parse 3
/* SUMMARY
/* locate macro references in string
/* SYNOPSIS
/* #include <mac_parse.h>
/*
/* int mac_parse(string, action, context)
/* const char *string;
/* int (*action)(int type, VSTRING *buf, void *context);
/* DESCRIPTION
/* This module recognizes macro expressions in null-terminated
/* strings. Macro expressions have the form $name, $(text) or
/* ${text}. A macro name consists of alphanumerics and/or
/* underscore. Text other than macro expressions is treated
/* as literal text.
/*
/* mac_parse() breaks up its string argument into macro references
/* and other text, and invokes the \fIaction\fR routine for each item
/* found. With each action routine call, the \fItype\fR argument
/* indicates what was found, \fIbuf\fR contains a copy of the text
/* found, and \fIcontext\fR is passed on unmodified from the caller.
/* The application is at liberty to clobber \fIbuf\fR.
/* .IP MAC_PARSE_LITERAL
/* The content of \fIbuf\fR is literal text.
/* .IP MAC_PARSE_EXPR
/* The content of \fIbuf\fR is a macro expression: either a
/* bare macro name without the preceding "$", or all the text
/* inside $() or ${}.
/* .PP
/* The action routine result value is the bit-wise OR of zero or more
/* of the following:
/* .IP MAC_PARSE_ERROR
/* A parsing error was detected.
/* .IP MAC_PARSE_UNDEF
/* A macro was expanded but not defined.
/* .PP
/* Use the constant MAC_PARSE_OK when no error was detected.
/* SEE ALSO
/* dict(3) dictionary interface.
/* DIAGNOSTICS
/* Fatal errors: out of memory. malformed macro name.
/*
/* The result value is the bit-wise OR of zero or more of the
/* following:
/* .IP MAC_PARSE_ERROR
/* A parsing error was detected.
/* .IP MAC_PARSE_UNDEF
/* A macro was expanded but not defined.
/* LICENSE
/* .ad
/* .fi
/* The Secure Mailer license must be distributed with this software.
/* AUTHOR(S)
/* Wietse Venema
/* IBM T.J. Watson Research
/* P.O. Box 704
/* Yorktown Heights, NY 10598, USA
/*--*/
/* System library. */
#include <sys_defs.h>
#include <ctype.h>
/* Utility library. */
#include <msg.h>
#include <mac_parse.h>
/*
* Helper macro for consistency. Null-terminate the temporary buffer,
* execute the action, and reset the temporary buffer for re-use.
*/
#define MAC_PARSE_ACTION(status, type, buf, context) \
do { \
VSTRING_TERMINATE(buf); \
status |= action((type), (buf), (context)); \
VSTRING_RESET(buf); \
} while(0)
/* mac_parse - split string into literal text and macro references */
int mac_parse(const char *value, MAC_PARSE_FN action, void *context)
{
const char *myname = "mac_parse";
VSTRING *buf = vstring_alloc(1); /* result buffer */
const char *vp; /* value pointer */
const char *pp; /* open_paren pointer */
const char *ep; /* string end pointer */
static char open_paren[] = "({";
static char close_paren[] = ")}";
int level;
int status = 0;
#define SKIP(start, var, cond) do { \
for (var = start; *var && (cond); var++) \
/* void */; \
} while (0)
if (msg_verbose > 1)
msg_info("%s: %s", myname, value);
for (vp = value; *vp;) {
if (*vp != '$') { /* ordinary character */
VSTRING_ADDCH(buf, *vp);
vp += 1;
} else if (vp[1] == '$') { /* $$ becomes $ */
VSTRING_ADDCH(buf, *vp);
vp += 2;
} else { /* found bare $ */
if (VSTRING_LEN(buf) > 0)
MAC_PARSE_ACTION(status, MAC_PARSE_LITERAL, buf, context);
vp += 1;
pp = open_paren;
if (*vp == *pp || *vp == *++pp) { /* ${x} or $(x) */
level = 1;
vp += 1;
for (ep = vp; level > 0; ep++) {
if (*ep == 0) {
msg_warn("truncated macro reference: \"%s\"", value);
status |= MAC_PARSE_ERROR;
break;
}
if (*ep == *pp)
level++;
if (*ep == close_paren[pp - open_paren])
level--;
}
if (status & MAC_PARSE_ERROR)
break;
vstring_strncat(buf, vp, level > 0 ? ep - vp : ep - vp - 1);
vp = ep;
} else { /* plain $x */
SKIP(vp, ep, ISALNUM(*ep) || *ep == '_');
vstring_strncat(buf, vp, ep - vp);
vp = ep;
}
if (VSTRING_LEN(buf) == 0) {
status |= MAC_PARSE_ERROR;
msg_warn("empty macro name: \"%s\"", value);
break;
}
MAC_PARSE_ACTION(status, MAC_PARSE_EXPR, buf, context);
}
}
if (VSTRING_LEN(buf) > 0 && (status & MAC_PARSE_ERROR) == 0)
MAC_PARSE_ACTION(status, MAC_PARSE_LITERAL, buf, context);
/*
* Cleanup.
*/
vstring_free(buf);
return (status);
}
#ifdef TEST
/*
* Proof-of-concept test program. Read strings from stdin, print parsed
* result to stdout.
*/
#include <vstring_vstream.h>
/* mac_parse_print - print parse tree */
static int mac_parse_print(int type, VSTRING *buf, void *unused_context)
{
char *type_name;
switch (type) {
case MAC_PARSE_EXPR:
type_name = "MAC_PARSE_EXPR";
break;
case MAC_PARSE_LITERAL:
type_name = "MAC_PARSE_LITERAL";
break;
default:
msg_panic("unknown token type %d", type);
}
vstream_printf("%s \"%s\"\n", type_name, vstring_str(buf));
return (0);
}
int main(int unused_argc, char **unused_argv)
{
VSTRING *buf = vstring_alloc(1);
while (vstring_fgets_nonl(buf, VSTREAM_IN)) {
mac_parse(vstring_str(buf), mac_parse_print, (void *) 0);
vstream_fflush(VSTREAM_OUT);
}
vstring_free(buf);
return (0);
}
#endif
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