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/*!
 @file    $Source: /cvs/ics/MakeTools/rm_version/rm_version.c,v $
 $Name:  $
 $Revision: 1.5 $
 $Date: 2015/01/22 18:04:00 $
 @brief   Program to remove version strings appended at end of file by prep
 */

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <ctype.h>
#include <errno.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <getopt.h>

extern int ftruncate(int __fd, off_t __length);


/*!
Remove the version string from a .uid or Linux/Cygwin/MIPS a.out file

This scans the last 1024 bytes of the given file for a
version string which starts with "version_marker:"
If the pattern is matched, the file is truncated such that
"version_marker:" and all bytes which follow it are
removed from the file.

THIS SHOULD ONLY BE RUN AGAINST FILES WHICH prep MAY HAVE
APPENDED A VERSION STRING TO.  FOR OTHER FILES WHICH PREP
EDITS WITH mcs OR sed, THIS MAY CORRUPT THE FILE.

The scan for "version_marker" is done by a reverse scan
of the last 1024 bytes of the file, it stops on the first match

@heading Usage
	rm_version [-m version_marker] file ...
@param version_marker - version marker to look for, default is
		"ICS VERSION STRING"
@param file - name of a file which may have a version string
		appended to it
*/

/* the string we are looking for */
#define MAGIC_STRING "ICS VERSION STRING:"
int magiclen;	/* length of MAGIC_STRING */
const char* magic=MAGIC_STRING;

/*!
remove the version string from the specified file

@param filename - name of file to fix

@return 0 on success, 1 on failure
*/
int fix_file(char* filename)
{
	int fd;
	struct stat statbuf;
	int end;	/* offset of last 1024 bytes of file */
	int size;	/* size of file starting at offset end */
#define MAXBUF 1024
	char buffer[MAXBUF];	/* holding area for scan */
	int offset;	/* current offset from end for scan */

	if (stat(filename, &statbuf) == -1
	    || (fd = open(filename, O_RDWR)) == -1)
	{
		fprintf(stderr, "rm_version: Can't open: ");
		perror(filename);
		return(1);
	}
	if (statbuf.st_size < MAXBUF)
	{
		/* small file, limit to file size */
		end = 0;
		size = statbuf.st_size;
	} else {
		end = statbuf.st_size - MAXBUF;
		size = MAXBUF;
	}
	if (lseek(fd, end, SEEK_SET) == -1)
	{
		fprintf(stderr, "rm_version: Can't seek: ");
		perror(filename);
		close(fd);
		return(1);
	}
	/* unfortunately CYGWIN or NT seem to be off on st_size since
	 * you typically can't read size bytes here.  Linux is fine
	 */
	/*if (read(fd, buffer, size) != size)*/
	if (read(fd, buffer, size) == -1)
	{
		fprintf(stderr, "rm_version: Can't read: ");
		perror(filename);
		close(fd);
		return(1);
	}
	/* scan buffer for 'ICS VERSION STRING' */
	for (offset = size-magiclen; offset >= 0; offset--)
	{
		if (strncmp(buffer+offset, magic, magiclen) == 0)
		{
			goto found;
		}
	}
	/* not found */
	close(fd);
	return(0);

found:
	/* found the string at offset */
	if (ftruncate(fd, end+offset) == -1)
	{
		fprintf(stderr, "rm_version: Can't truncate: ");
		perror(filename);
		close(fd);
		return(1);
	}
	close(fd);
	printf("%s: %d bytes removed\n", filename, size-offset);
	return(0);
}

void usage(void)
{
	fprintf(stderr, "Usage: rm_version [-m version_marker] file ...");
	exit(2);
}

int main(int argc, char** argv)
{
	int i;
	int res;
	int c;
	extern char* optarg;
	extern int optind;

	while ((c = getopt(argc, argv, "m:")) != -1)
	{
		switch (c)
		{
			case 'm':	/* version_marker */
				magic = optarg;
				break;
			case '?':
				usage();
		}
	}
	
	if (argc == optind)
	{
		usage();
	}
	magiclen = strlen(magic);
	res = 0;
	for (i=optind; i< argc; i++)
	{
		res |= fix_file(argv[i]);
	}

	return res;
}