subst_tool.c

/*
** mouse:~ppr/src/subst_tool.c
** Copyright 1995--2006, Trinity College Computing Center.
** Written by David Chappell.
**
** Redistribution and use in source and binary forms, with or without
** modification, are permitted provided that the following conditions are met:
**
** * Redistributions of source code must retain the above copyright notice,
** this list of conditions and the following disclaimer.
** 
** * 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.
**
** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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 COPYRIGHT HOLDERS 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.
**
** Last modified 7 April 2006.
*/

/*
 * This program is a filter which inserts the values of environment variables at marked
 * locations.  It is designed to emulate autoconf.  The patterns are:
 * 
 * @NAME@
 * 		Inserts the value of NAME, if defined, otherwise program aborts.
 * #undef NAME
 * 		Is replaced with
 * 			#define NAME VALUE
 * 		if NAME is defined, otherwise is left unchanged.
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int main(int argc, char *argv[])
	{
	int linenum = 0;
	char line[256];
	char *p;

	while(fgets(line, sizeof(line), stdin))
		{
		linenum++;

		/* If the line begins with:
		 * #undef SYMBOL
		 * and SYMBOL is a defined environment variable, replace
		 * it with:
		 * #define SYMBOL value
		 */
		if(strncmp(line, "#undef ", 7) == 0)
			{
			char *p2, *value;
			p = line + 7;
			if((p2 = strchr(p, '\n')))
				{
				*p2 = '\0';
				if((value = getenv(p)) && *value)
					{
					if(strspn(value, "-.0123456789") == strlen(value))	/* if numberic */
						printf("#define %s %s\n", p, value);
					else
						printf("#define %s \"%s\"\n", p, value);
					continue;
					}
				else
					{
					*p2 = '\n';
					/* fall thru */
					}
				}
			}

		/*
		 * Print the line while replacing @SYMBOL@ where SYMBOL is a name
		 * consisting exclusively of upper-case letters, digits, and 
		 * underscore with the value of the environment variable of that name.
		 * If the environment variable is not defined, abort.
		 */
		for(p=line; *p; p++)
			{
			if(*p == '@')
				{
				char *end;
				const char *value;
				if((end = strchr(p+1, '@')))	/* if there is another @ sign, */
					{
					*end = '\0';
					if(strspn(p+1, "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789_") == strlen(p+1))
						{
						if(!(value = getenv(p+1)))
							{
							fprintf(stderr, "%s: no %s in environment\n", argv[0], p+1);
							fprintf(stderr, "This may mean that your Makefile.conf is out-of-date and you\n"
											"should run ./Configure to regenerate it.\n");

							return 1;
							}
						fputs(value, stdout);
						p = end;
						continue;
						}
					else
						{
						*end = '@';
						}
					}
				}
			fputc(*p, stdout);
			}
		}

	return 0;
	}

/* end of file */