some zip files appear not to have directory entries so files cannot be extracted
untile the apropriate hierarchy has been made (by hand). This patch adds a -a,
auto create directories option to unzip which does this for you.

-Steve

Reference: /n/sources/patch/applied/zip-auto-dirs
Date: Thu Aug  9 12:24:29 CES 2007
Signed-off-by: steve@quintile.net

--- /sys/man/1/gzip	Thu Aug  9 12:21:15 2007
+++ /sys/man/1/gzip	Thu Aug  9 12:21:12 2007
@@ -39,7 +39,7 @@
 ]
 .PP
 .B zip
-.RB [ -vD [ 1-9 ]]
+.RB [ -avD [ 1-9 ]]
 .RB [ -f
 .IR zipfile ]
 .I file
@@ -131,6 +131,10 @@
 .PP
 The options are:
 .TP 0.6i
+.B -a
+Automaticialy creates directories as needed, needed for zip files
+created by broken implementations which omit directories.
+.TP
 .B -c
 Write to standard output rather than creating an output file.
 .TP
--- /sys/src/cmd/gzip/unzip.c	Thu Aug  9 12:21:31 2007
+++ /sys/src/cmd/gzip/unzip.c	Thu Aug  9 12:21:27 2007
@@ -47,6 +47,7 @@
 static	ulong	wlen;
 static	jmp_buf	zjmp;
 static	jmp_buf	seekjmp;
+static	int	autodir;
 
 static void
 usage(void)
@@ -65,6 +66,9 @@
 	stream = 0;
 	zfile = nil;
 	ARGBEGIN{
+	case 'a':
+		autodir++;
+		break;
 	case 'D':
 		debug++;
 		break;
@@ -338,6 +342,55 @@
 	}
 }
 
+static int mkdirs(char *);
+
+/*
+ * if any directories leading up to path don't exist, create them.
+ * modifies but restores path.
+ */
+static int
+mkpdirs(char *path)
+{
+	int rv = 0;
+	char *sl = strrchr(path, '/');
+print("%s\n", path);
+	if (sl != nil) {
+		*sl = '\0';
+		rv = mkdirs(path);
+		*sl = '/';
+	}
+	return rv;
+}
+
+/*
+ * if path or any directories leading up to it don't exist, create them.
+ * modifies but restores path.
+ */
+static int
+mkdirs(char *path)
+{
+	int fd;
+
+	if (access(path, AEXIST) >= 0)
+		return 0;
+
+	/* make presumed-missing intermediate directories */
+	if (mkpdirs(path) < 0)
+		return -1;
+
+	/* make final directory */
+	fd = create(path, OREAD, 0755|DMDIR);
+	if (fd < 0)
+		/*
+		 * we may have lost a race; if the directory now exists,
+		 * it's okay.
+		 */
+		return access(path, AEXIST) < 0? -1: 0;
+	close(fd);
+	return 0;
+}
+
+
 /*
  * extracts a single entry from a zip file
  * czh is the optional corresponding central directory entry
@@ -395,6 +448,8 @@
 				free(d);
 			}
 		}else if(ok){
+			if(autodir)
+				mkpdirs(zh.file);
 			fd = create(zh.file, OWRITE, 0664);
 			if(fd < 0){
 				fprint(2, "unzip: can't create %s: %r\n", zh.file);