Subversion Repositories planix.SVN

/*

 *

 * Pathname management routines for DWB C programs.

 *

 * Applications should initialize a dwbinit array with the string

 * pointers and arrays that need to be updated, and then hand that

 * array to DWBinit before much else happens in their main program.

 * DWBinit calls DWBhome to get the current home directory. DWBhome

 * uses the last definition of DWBENV (usually "DWBHOME") in file

 * DWBCONFIG (e.g., /usr/lib/dwb3.4) or the value assigned to that

 * variable in the environment if the DWBCONFIG file doesn't exist,

 * can't be read, or doesn't define DWBENV.

 *

 * DWBCONFIG must be a simple shell script - comments, a definition

 * of DWBHOME, and perhaps an export or echo is about all that's

 * allowed. The parsing in DWBhome is simple and makes no attempt

 * to duplicate the shell. It only looks for DWBHOME= as the first

 * non-white space string on a line, so

 *

 *	#

 *	# A sample DWBCONFIG shell script

 *	#

 *

 *	DWBHOME=/usr/add-on/dwb3.4

 *	export DWBHOME

 *

 * means DWBhome would return "/usr/add-on/dwb3.4" for the DWB home

 * directory. A DWBCONFIG file means there can only be one working

 * copy of a DWB release on a system, which seems like a good idea.

 * Using DWBCONFIG also means programs will always include correct

 * versions of files (e.g., prologues or macro packages).

 *

 * Relying on an environment variable guarantees nothing. You could

 * execute a version of dpost, but your environment might point at

 * incorrect font tables or prologues. Despite the obvious problems

 * we've also implemented an environment variable approach, but it's

 * only used if there's no DWBCONFIG file.

 *

 * DWBinit calls DWBhome to get the DWB home directory prefix and

 * then marches through its dwbinit argument, removing the default

 * home directory and prepending the new home. DWBinit stops when

 * it reaches an element that has NULL for its address and value

 * fields. Pointers in a dwbinit array are reallocated and properly

 * initialized; arrays are simply reinitialized if there's room.

 * All pathnames that are to be adjusted should be relative. For

 * example,

 *

 *	char	*fontdir = "lib/font";

 *	char	xyzzy[25] = "etc/xyzzy";

 *

 * would be represented in a dwbinit array as,

 *

 *	dwbinit allpaths[] = {

 *		&fontdir, NULL, 0,

 *		NULL, xyzzy, sizeof(xyzzy),

 *		NULL, NULL, 0

 *	};

 *		

 * The last element must have NULL entries for the address and

 * value fields. The main() routine would then do,

 *

 *	#include "dwbinit.h"

 *

 *	main() {

 *

 *		DWBinit("program name", allpaths);

 *		...

 *	}

 *

 * Debugging is enabled if DWBDEBUG is in the environment and has

 * the value ON. Output is occasionally useful and probably should

 * be documented.

 *

 */

#include <stdio.h>

#include <ctype.h>

#include <string.h>

#include <stdlib.h>

#include "dwbinit.h"

#ifndef DWBCONFIG

#define DWBCONFIG	"/dev/null"

#endif

#ifndef DWBENV

#define DWBENV		"DWBHOME"

#endif

#ifndef DWBHOME

#define DWBHOME		""

#endif

#ifndef DWBDEBUG

#define DWBDEBUG	"DWBDEBUG"

#endif

#ifndef DWBPREFIX

#define DWBPREFIX	"\\*(.P"

#endif

/*****************************************************************************/

void DWBdebug(dwbinit *ptr, int level)

{

    char	*path;

    char	*home;

    static char	*debug = NULL;

/*

 *

 * Debugging output, but only if DWBDEBUG is defined to be ON in the

 * environment. Dumps general info the first time through.

 *

 */

    if ( debug == NULL && (debug = getenv(DWBDEBUG)) == NULL )

	debug = "OFF";

    if ( strcmp(debug, "ON") == 0 ) {

	if ( level == 0 ) {

	    fprintf(stderr, "Environment variable: %s\n", DWBENV);

	    fprintf(stderr, "Configuration file: %s\n", DWBCONFIG);

	    fprintf(stderr, "Default home: %s\n", DWBHOME);

	    if ( (home = DWBhome()) != NULL )

		fprintf(stderr, "Current home: %s\n", home);

	}   /* End if */

	fprintf(stderr, "\n%s pathnames:\n", level == 0 ? "Original" : "Final");

	for ( ; ptr->value != NULL || ptr->address != NULL; ptr++ ) {

	    if ( (path = ptr->value) == NULL ) {

		path = *ptr->address;

		fprintf(stderr, " pointer: %s\n", path);

	    } else fprintf(stderr, " array[%d]: %s\n", ptr->length, path);

	    if ( level == 0 && *path == '/' )

		fprintf(stderr, "  WARNING - absolute path\n");

	}   /* End for */

    }	/* End if */

}   /* End of DWBdebug */

/*****************************************************************************/

char *DWBhome(void)

{

    FILE	*fp;

    char	*ptr;

    char	*path;

    int		len;

    char	buf[200];

    char	*home = NULL;

/*

 *

 * Return the DWB home directory. Uses the last definition of DWBENV

 * (usually "DWBHOME") in file DWBCONFIG (perhaps /usr/lib/dwb3.4) or

 * the value assigned to the variable named by the DWBENV string in

 * the environment if DWBCONFIG doesn't exist or doesn't define DWBENV.

 * Skips the file lookup if DWBCONFIG can't be read. Returns NULL if

 * there's no home directory.

 *

 */

    if ( (fp = fopen(DWBCONFIG, "r")) != NULL ) {

	len = strlen(DWBENV);

	while ( fgets(buf, sizeof(buf), fp) != NULL ) {

	    for ( ptr = buf; isspace(*ptr); ptr++ ) ;

	    if ( strncmp(ptr, DWBENV, len) == 0 && *(ptr+len) == '=' ) {

		path = ptr + len + 1;

		for ( ptr = path; !isspace(*ptr) && *ptr != ';'; ptr++ ) ;

		*ptr = '\0';

		if ( home != NULL )

		    free(home);

		if ( (home = malloc(strlen(path)+1)) != NULL )

		    strcpy(home, path);

	    }	/* End if */

	}   /* End while */

	fclose(fp);

    }   /* End if */

    if ( home == NULL ) {

	if ( (home = getenv(DWBENV)) == NULL ) {

	    if ( (home = DWBHOME) == NULL || *home == '\0' || *home == ' ' )

		home = NULL;

	}   /* End if */

    }	/* End if */

    while (home && *home == '/' && *(home +1) == '/')	/* remove extra slashes */

	home++;

    return(home);

}   /* End of DWBhome */

/*****************************************************************************/

void DWBinit(char *prog, dwbinit *paths)

{

    char	*prefix;

    char	*value;

    char	*path;

    int		plen;

    int		length;

    dwbinit	*opaths = paths;

/*

 *

 * Adjust the pathnames listed in paths, using the home directory

 * returned by DWBhome(). Stops when it reaches an element that has

 * NULL address and value fields. Assumes pathnames are relative,

 * but changes everything. DWBdebug issues a warning if an original

 * path begins with a /.

 *

 * A non-NULL address refers to a pointer, which is reallocated and

 * then reinitialized. A NULL address implies a non-NULL value field

 * and describes a character array that we only reinitialize. The

 * length field for an array is the size of that array. The length

 * field of a pointer is an increment that's added to the length

 * required to store the new pathname string - should help when we

 * want to change character arrays to pointers in applications like

 * troff.

 *

 */

    if ( (prefix = DWBhome()) == NULL ) {

	fprintf(stderr, "%s: no DWB home directory\n", prog);

	exit(1);

    }	/* End if */

    DWBdebug(opaths, 0);

    plen = strlen(prefix);

    for ( ; paths->value != NULL || paths->address != NULL; paths++ ) {

	if ( paths->address == NULL ) {

	    length = 0;

	    value = paths->value;

	} else {

	    length = paths->length;

	    value = *paths->address;

	}   /* End else */

	length += plen + 1 + strlen(value);	/* +1 is for the '/' */

	if ( (path = malloc(length+1)) == NULL ) {

	    fprintf(stderr, "%s: can't allocate pathname memory\n", prog);

	    exit(1);

	}   /* End if */

	if ( *value != '\0' ) {

	    char *eop = prefix;

	    while(*eop++)

		;

	    eop -= 2;

	    if (*value != '/' && *eop != '/') {

		sprintf(path, "%s/%s", prefix, value);

	    } else if (*value == '/' && *eop == '/') {

		value++;

		sprintf(path, "%s%s", prefix, value);

	    } else

		sprintf(path, "%s%s", prefix, value);

	} else

		sprintf(path, "%s", prefix);

	if ( paths->address == NULL ) {

	    if ( strlen(path) >= paths->length ) {

		fprintf(stderr, "%s: no room for %s\n", prog, path);

		exit(1);

	    }	/* End if */

	    strcpy(paths->value, path);

	    free(path);

	} else *paths->address = path;

    }	/* End for */

    DWBdebug(opaths, 1);

}   /* End of DWBinit */

/*****************************************************************************/

void DWBprefix( char *prog, char *path, int length)

{

    char	*home;

    char	buf[512];

    int		len = strlen(DWBPREFIX);

/*

 *

 * Replace a leading DWBPREFIX string in path by the current DWBhome().

 * Used by programs that pretend to handle .so requests. Assumes path

 * is an array with room for length characters. The implementation is

 * not great, but should be good enough for now. Also probably should

 * have DWBhome() only do the lookup once, and remember the value if

 * called again.

 * 

 */

    if ( strncmp(path, DWBPREFIX, len) == 0 ) {

	if ( (home = DWBhome()) != NULL ) {

	    if ( strlen(home) + strlen(path+len) < length ) {

		sprintf(buf, "%s%s", home, path+len);

		strcpy(path, buf);		/* assuming there's room in path */

	    } else fprintf(stderr, "%s: no room to grow path %s", prog, path);

	}   /* End if */

    }	/* End if */

}   /* End of DWBprefix */

/*****************************************************************************/