/*
 * uundo.c: extract a multi-part uuencoded archive               Version 1.3a
 * written by Aaron Giles                                           03/08/92
 * 
 * usage:
 *   uundo [-hLloqv] file1 [file2 [...]]
 *   uundo [-hLloqv] < file
 *
 * options:
 *   -h  header: write the article header of the earliest part to target.hdr
 *   -L  lower all: convert all characters in all filenames to lower case
 *   -l  lower: convert only all-upper-case filenames to lower case
 *   -o  overwrite: automatically overwrite existing files without permission
 *   -q  query: allow overwriting of existing files, but ask permission first
 *   -v  verbose: display part numbers and status info
 *
 * special features:
 *   - does not require all parts to be in order*
 *   - attempts to identify missing parts*
 *   - works on uuencoded files included in shar archives
 *   - can accept either single or multiple files on the command line
 *   - can accept stream input from stdin
 * (* requires part numbering informating in the subject line of each part)
 *
 * bugs/requests/modifications to:
 *   a-giles@uchicago.edu     -or-
 *   gile@midway.uchicago.edu -or-
 *   giles@hep.uchicago.edu
 *
 * philosophy:
 *   I will try my best to keep up with any bug reports (first priority) or
 *   new feature requests.  Note that my primary goal is robustness, so that
 *   requests which would overly complicate things or result in "flaky" code
 *   will very likely not be put in.
 *
 * copyright control:
 *   This program is public domain, though copyrighted (c) 1992 by its
 *   author, Aaron Giles.  If you wish to distribute modified copies of
 *   this program, please contact the author first.
 *
 * standard disclaimer:
 *   Use this program at your own risk.  The author takes no responsibility
 *   for any loss of data or damage that results from using this program.
 *
 * known problems/limitations:
 *   - cannot handle multiple target files in the same input file (sorry!)
 *   - can't yet accept input piped from rn or trn
 *
 * to be added in future versions:
 *   - support for saving header information
 *   - support for piping, allowing use with rn/trn
 *
 * version history:
 *   1.0 (2/11/92) - initial release
 *   1.1 (2/13/92) - added stdin support for preliminary use with rn
 *                   no longer so restrictive on the first line of each part
 *                   added verbose option
 *                   added a warning to overwrite existing files
 *                   added an option to turn off this warning
 *                   now attempts to make file writeable before overwriting
 *                   fixed problem with "BEGIN..." lines fooling the decoder
 *   1.2 (2/21/92) - added force lowercase options
 *                   changed procedure dealing with conflicting filenames
 *                   added query option
 *                   now uses process ID in temporary names to avoid conflicts
 *                   output directory can be set via UUNDO environment variable
 *  1.21 (2/28/92) - fixed bug that would alter directory attributes if none
 *                      of the input files were found 
 *   1.3 (3/08/92) - added support for maximum filename length
 *                 - refined handling of jumbled and unlabelled parts
 *                 - fixed the aforementioned bug -- again
 *                 - added option to write header of earliest part to a file
 */

#include <ctype.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <unistd.h>

/*
 * Platform-specific definitions
 */
#define PATHSEP '/'               /* path separator character */
#define MAXNAMELEN 32             /* maximum length of a given filename */
#define TEMPNAME "/usr/tmp/uu"    /* prefix for temporary files */

/*
 * Arbitrary global definitions
 */
#define MAXLEN 256                /* maximum length of strings/pathnames */
#define MAXPARTS 256              /* maximum number of parts in file */
#define BUFSIZE 32768             /* size of temporary buffer */

/*
 * Header storage structure
 */
typedef struct header_str *header_ptr;
struct header_str {
	char *line;
	header_ptr next;
};

/*
 * Global variables
 */
int debug = 0;				/* debug flag */
int header = 0;				/* header flag */
int Lower = 0;				/* all lower case flag */
int lower = 0;				/* lower case flag */
int overwrite = 0;			/* overwrite flag */
int query = 0;				/* query flag */
int verbose = 0;			/* verbose flag */

int part, total;			/* current part number and total count */
int pending[MAXPARTS];		/* table of pending entries */
char lastsubj[MAXLEN];		/* text of the last subject line read */

int partswritten;			/* total number of parts written to target */
long int byteswritten;		/* total number of bytes written to target */

FILE *targetfile;			/* stream pointer for target file */
char targetname[MAXLEN];	/* name of target file */
char *targetpath;			/* pointer to path for output directory */
int targetmode;				/* file mode for final target */

header_ptr hdrroot = NULL;	/* linked list of header lines */
header_ptr hdrlast = NULL;	/* last group of header lines read */
int hdrpart;				/* part associated with this header */

pid_t pid;					/* process ID of this program */

/*
 * tempname:
 *	 put temporary file name for part num into string variable name
 */
char *tempname(int num, char *name) {
	strcpy(name, TEMPNAME);
	sprintf(name+strlen(name), "%ld.%03i", pid, num);
	return name;
}

/*
 * filename:
 *	 combine path, filename, and iteration, checking for length
 */
char *filename(char *dest, char *path, char *file, int iter) {
	char *p, *q;
	char suffix[4];
	
	*dest = 0;
	if (path) strcat(dest, path);
	if ((!path) || (dest[strlen(dest) - 1] != PATHSEP)) {
		dest[strlen(dest) + 1] = 0;
		dest[strlen(dest)] = PATHSEP;
	}
	q = dest + strlen(dest);
	for (p = file + strlen(file); (*(p - 1) != PATHSEP) && (p > file); p--);
	strncat(dest, p, MAXNAMELEN);
	if (iter) {
		if (iter > 0) sprintf(suffix, ".%02i", iter);
		else strcpy(suffix, ".hdr");
		if (strlen(q) > (MAXNAMELEN - 3))
			strcpy(q + MAXNAMELEN - 3, suffix);
		else
			strcpy(q + strlen(q), suffix);
	}
	return dest;
}

/*
 * createfile:
 *	 attempt to create the named file
 */
FILE *createfile(char *name, char *type) {
	FILE *file;
	if (!(file = fopen(name, "w")))
		fprintf(stderr, "uundo: unable to create %s file %s\n", type, name);
	return file;
}

/*
 * openfile:
 *	 attempt to open the named file for reading
 */
FILE *openfile(char *name, char *type) {
	FILE *file;
	if (!(file = fopen(name, "r")))
		fprintf(stderr, "uundo: unable to open %s file %s\n", type, name);
	return file;
}

/*
 * deletefile:
 *	 remove the named file
 */
void deletefile(char *name) {
	chmod(name, 0666);
	if (unlink(name))
		fprintf(stderr, "uundo: unable to remove file %s\n", name);
}

/*
 * checkfile:
 *	 check for existence of target file before overwriting
 */
int checkfile(char *name) {
	FILE *file;
	char s[MAXLEN];
	int count = 0;

	while (file = fopen(filename(targetname, targetpath, name, count++), "r")) {
		fclose(file);
		if (overwrite) {
			deletefile(targetname);
			return 1;
		} else if (query) {
			fprintf(stderr, "uundo: %s already exists: overwrite? ", name);
			gets(s);
			if ((*s == 'Y') || (*s == 'y')) {
				deletefile(targetname);
				return 1;
			}
		}
	}
	return 1;
}

/*
 * readline:
 *	 input a line and strip the newline character
 */
int readline(FILE *file, char *s) {
	int l;

	if (!fgets(s, MAXLEN, file)) return 0;
	if ((l = strlen(s)) == (MAXLEN - 1)) {
		fprintf(stderr, "uundo: invalid input file format\n");
		exit(1);
	}
	s[l - 1] = 0;
	return 1;
}

/*
 * addhdr:
 *	 add a header line to the end of the linked list
 */
header_ptr addhdr(header_ptr root, char *line) {
	header_ptr new, cur;

	if (new = (header_ptr)malloc(sizeof(struct header_str))) {
		new->next = NULL;
		if (new->line = (char *)malloc(strlen(line) + 1)) {
			strcpy(new->line, line);
			if (root) {
				for (cur = root; cur->next; cur = cur->next);
				cur->next = new;
			} else root = new;
			return root;
		}
	}
	fprintf(stderr, "uundo: out of memory!");
	exit(1);
}

/*
 * killhdr:
 *	 kill the linked list of header lines
 */
header_ptr killhdr(header_ptr root) {
	header_ptr cur, next;

	if (!root) return NULL;
	for (cur = root; cur; cur = next) {
		free(cur->line);
		next = cur->next;
		free(cur);
	}
	return NULL;
}

/*
 * writehdr:
 *	 write out the linked list of headers
 */
void writehdr(header_ptr root) {
	FILE *hdrfile;
	char hdrname[MAXLEN];

	if ((!header) || (!root)) return;
	filename(hdrname, targetpath, targetname, -1);
	if (!(hdrfile = createfile(hdrname, "header"))) exit(1);
	for ( ; root->next; root = root->next)
		fprintf(hdrfile, "%s\n", root->line);
	fclose(hdrfile);
}

/*
 * uuline:
 *	 determine if the given line is a correct uuencoded line
 */
int uuline(char *s, int full) {
	int l, len, max, min;
	
	if ((strncasecmp(s, "end", 3) == 0) ||
		(strncasecmp(s, "begin", 5) == 0) ||
		((l = s[0] - ' ') & 0xc0)) return 0;
	min = ((l * 4) + 2) / 3;
	max = ((min + 3) / 4) * 4 + 1;
	len = strlen(s) - 1;
	if ((len < min) || (len > max)) return 0;
	if (!full && ((l == 45) || (l == 0))) return 1;
	for (s++; *s; s++)
	  if ((*s < ' ') || (*s > '`')) return 0;
	return 1;
}

/*
 * headerstate:
 *	 determine whether we should be saving (1) or ignoring (0) header lines
 */
int headerstate(char *line, int oldstate) {
	if (oldstate) {
		if ((line[0] == '#') && (strstr(line, "/bin/sh"))) return 0;
		return 1;
	} else {
		while (!isspace(*line) && *line && (*line != ':')) line++;
		if (*line == ':') return 1;
		return 0;
	}
}

/*
 * decode:
 *	 decode a uuencoded line and output the binary data to ouf
 */
void decode(FILE *outf, char *line) {
	int count = line[0] - ' ';
	int i, j;

	if (debug) printf("%s\n", line);
	for (j = 1; line[j]; j++) line[j] = (line[j] - ' ') & 0x3f;
	for (i = 0, j = 1; i < count; i += 3, j += 4) {
		line[i]	 = ((line[j]	 << 2) | (line[j+1] >> 4)) & 0xff;
		line[i+1] = ((line[j+1] << 4) | (line[j+2] >> 2)) & 0xff;
		line[i+2] = ((line[j+2] << 6) | (line[j+3]		 )) & 0xff;
	}
	if (count) {
		if (outf == targetfile) byteswritten += count;
		if (count -= fwrite(line, 1, count, outf)) {
			fprintf(stderr, "uundo: unable to write to output file\n");
			exit(1);
		}
	}
}

/*
 * unpend:
 *	 append pending file to the target
 */
void unpend(int number) {
	int i;
	FILE *inf;
	char inname[MAXLEN];
	char buffer[BUFSIZE];

	if (!(inf = openfile(tempname(number, inname), "temporary"))) exit(1);
	while (i = fread(buffer, 1, BUFSIZE, inf)) {
		if (fwrite(buffer, 1, i, targetfile) != i) {
			fprintf(stderr, "uundo: unable to append temporary file %s\n", inname);
			exit(1);
		} else
			byteswritten += i;
	}
	fclose(inf);
	deletefile(inname);
	pending[number] = 0;
}

/*
 * parse:
 *	 determine part number and total number from subject header line
 */
void parse(char *p) {
	char *q;
	int i;
	
	part = -1;
	for (; *p; p++) {
		switch (*p) {
			case 'P': case 'p':
				if (isalpha(*(p - 1)) || (strncasecmp(p, "part", 4)) ||
			isalpha(*(p + 4))) continue;
				p += 4;
				break;
			case '(': case '{': case '[':
				p++;
				break;
			case 'O': case 'o':
				if (isalpha(*(p - 1)) || (strncasecmp(p, "of", 2)) ||
					isalpha(*(p + 2))) continue;
			  case '|':
			  case '/':
				for (q = p; isspace(*(q - 1)); q--);
				if (!isdigit(*(q - 1))) continue;
				while (isdigit(*(q - 1))) q--;
				if (isalpha(*(q - 1))) continue;
				p = q;
				break;
			default:
				continue;
		}			
		i = (int)strtol(p, &q, 10);
		if (p == q) { p--; continue; }
		part = i;
		for (p = q; isspace(*p); p++);
		switch (*p) {
			case '|':
			case '/':
				p++;
				break;
			case 'o': case 'O':
				if (strncasecmp(p, "of", 2) == 0) {
					p+=2;
					break;
				}
			default:
				p--;
				continue;
			}
		while (isspace(*p)) p++;
		i = (int)strtol(p, &q, 10);
		if (p == q) { p--; continue; }
		total = i;
		return;
	}
}

/*
 * initfile:
 *	 parse the uuencode header line and initialize the output file
 */
int initfile(char *p) {
	char *q;
	
	if (partswritten > 0) {
		fprintf(stderr, "uundo: found extra part 1, ignored\n");
		return 1;
	}
	while (isspace(*p) && *p) p++;
	if (*p) targetmode = (int)strtol(p, (char **)NULL, 8);
	else targetmode = 0666;
	while (!isspace(*p) && *p) p++;
	while (isspace(*p) && *p) p++;
	if (!*p) {
		strcpy(p, "a.out");
		fprintf(stderr, "uundo: filename not found, using a.out instead\n");
	}
	for (q = p; *q && !islower(*q); q++);
	if (Lower || (lower && !*q))
		for (q = p; *q; *q = tolower(*q), q++);
	if (!checkfile(p)) exit(1);
	if (!(targetfile = createfile(targetname, "output"))) exit(1);
	partswritten = 0;
	return 0;
}

/*
 * startpart:
 *	 figure out where to output the newly-found part
 */
FILE *startpart() {
	char name[MAXLEN];
	FILE *outf;
	
	if (partswritten > 0)
		while (pending[partswritten + 1]) unpend(++partswritten);
	if ((part == -1) && (partswritten < 0)) {
		fprintf(stderr, "uundo: unnumbered part found out of order; ignored\n");
		return (FILE *)NULL;
	}
	if ((part == -1) || (part == (partswritten + 1)))
		return targetfile;
	if ((part <= partswritten) || (pending[part])) {
		fprintf(stderr, "uundo: found extra part %i, ignored\n", part);
		return (FILE *)NULL;
	}
	pending[part] = 1;
	if (!(outf = createfile(tempname(part, name), "temporary"))) exit(1);
	return outf;
}

/*
 * init:
 *	 initialize pending array and do general setup
 */
int init(int argc, char *argv[]) {
	int i;
	char *p;

	pid = getpid();
	targetpath = getenv("UUNDO");
	strcpy(lastsubj, "");
	 for (i = 1; argv[i] && (*argv[i] == '-'); i++) {
		for (p = argv[i] + 1; *p; p++) {
			switch (*p) {
				case 'd': debug = 1; break;
				case 'h': header = 1; break;
				case 'L': Lower = 1; break;
				case 'l': lower = 1; break;
				case 'o': overwrite = 1; break;
				case 'q': query = 1; break;
				case 'v': verbose = 1; break;
			}
		}
	}
	return i;
}

/*
 * initglobals:
 *	 reset all global variables in anticipation of next file
 */
void initglobals() {
	int i;
	
	for (i = 0; i < MAXPARTS; pending[i++] = 0);
	part = -1;
	total = 0;
	partswritten = -2;
	byteswritten = 0;
	targetname[0] = 0;
	targetmode = 0;
	hdrroot = killhdr(hdrroot);
	hdrlast = killhdr(hdrlast);
	hdrpart = MAXPARTS;
}

/*
 * findstart:
 *	 parse the header and skip garbage before uuencoded data
 */
FILE *findstart(FILE *inf) {
	FILE *outf;
	char line[MAXLEN];
	int ignore = 0, save = 0;

	while (readline(inf, line)) {
		if (!line[0]) continue;
		if ((header) && (save = headerstate(line, save)))
			hdrlast = addhdr(hdrlast, line);
		if (strncasecmp(line, "Subject:", 8) == 0) {
			ignore = 0;
			parse(line + 8);
		} else if (strncmp(line, "begin ", 6) == 0) {
			if (!(ignore = initfile(line + 6)))
			  return targetfile;
		} else if (!ignore && uuline(line, 1) &&
				 (line[0] != '#') && (line[0] != '-') && (line[0] != ' ')) {
			if (outf = startpart()) {
				decode(outf, line);
				return outf;
			} else ignore = 1;
		}
	}
	return (FILE *)NULL;
}

/*
 * partstatus:
 *	 display current part number and keep correct header info.
 */
void partstatus() {
	if (part < 0) part = partswritten + 1;
	if (header) {
		if (part < hdrpart) {
			hdrroot = killhdr(hdrroot);
			hdrroot = hdrlast;
			hdrpart = part;
			hdrlast = NULL;
		} else hdrlast = killhdr(hdrlast);
	}
	if (verbose) {
		if (total)
			fprintf(stderr, "uundo: found part %i of %i\n", part, total);
		else
			fprintf(stderr, "uundo: found part %i\n", part);
	}
}

/*
 * cleanup:
 *	 clean up our little mess
 */
void cleanup() {
	char name[MAXLEN];
	int i, found = 0;
	
	for (i = 0; i < MAXPARTS; found += pending[i++]);
	if ((partswritten < 0) && (found))
		fprintf(stderr, "uundo: missing file part 1\n");
	else if (partswritten >= 0) {
		while (pending[partswritten + 1]) unpend(++partswritten);
		if ((total) && (partswritten < total)) {
			fprintf(stderr, "uundo: missing part %i of %i; target removed\n",
				partswritten + 1, total);
			if (partswritten >= 0) deletefile(targetname);
		} else {
			if (targetmode) chmod(targetname, targetmode);
			if (verbose)
			  fprintf(stderr, "Wrote file %s (%i parts, %ld bytes)\n", targetname,
					  partswritten, byteswritten);
		}
		if (partswritten >= 0) fclose(targetfile);
	}
	for (i = 0; i < MAXPARTS; i++)
		if (pending[i]) deletefile(tempname(i, name));
	if (header) {
		writehdr(hdrroot);
		hdrroot = killhdr(hdrroot);
	}
}

/*
 * main program loop
 */
int main(int argc, char *argv[]) {
	FILE *infile = stdin, *outfile;
	int fptr, start;
	char line[MAXLEN];

	start = init(argc, argv);
	initglobals();
	for (fptr = start;
			 (fptr < argc) || ((fptr == start) && (argc == start)); fptr++) {
		if ((argc > start) && (!(infile = openfile(argv[fptr], "input"))))
			continue;
		while (outfile = findstart(infile)) {
			partstatus();
			while (readline(infile, line)) {
				if (!uuline(line, 0)) break;
				decode(outfile, line);
			}
			if (outfile != targetfile)
			  fclose(outfile);
			else
			  partswritten++;
		}
		fclose(infile);
	}
	cleanup();
}