1 files changed, 104 insertions, 0 deletions
diff --git a/unix/os/zfaloc.c b/unix/os/zfaloc.c
new file mode 100644
index 00000000..c0eb09cd
--- /dev/null
+++ b/unix/os/zfaloc.c
@@ -0,0 +1,104 @@
+/* Copyright(c) 1986 Association of Universities for Research in Astronomy Inc.
+ */
+
+#include <stdio.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <unistd.h>
+
+#define	import_kernel
+#define	import_knames
+#define import_spp
+#include <iraf.h>
+
+/* ZFALOC -- Preallocate space for a large file of known size, without having
+ * to physically write zero blocks.  In UNIX this is done by seeking to the
+ * desired end of file and writing some data.  Standard UNIX does not provide
+ * any way to allocate a contiguous or near-contiguous file.
+ */
+int
+ZFALOC (
+  PKCHAR  *fname,
+  XLONG	  *nbytes,
+  XINT	  *status
+)
+{
+	char	data = 0;
+	char	*s;
+	int	fd;
+	off_t	lseek();
+	extern	char *getenv();
+	extern  int  _u_fmode();
+
+
+	if ((fd = creat ((char *)fname, _u_fmode(FILE_MODEBITS))) == ERR) {
+	    *status = XERR;
+	    return (XERR);
+	}
+
+	/* Fix size of file by seeking to the end of file minus one byte,
+	 * and writing one byte of data.  UNIX will not allocate the remaining
+	 * fileblocks until they are written into at run time; when referenced
+	 * the blocks will be zero-fill on demand.
+	 */
+	if (*nbytes > 0) {
+	    if (lseek (fd, (off_t)(*nbytes - 1), 0) == ERR) {
+		close (fd);
+		*status = XERR;
+		return (XERR);
+	    }
+	    if (write (fd, &data, 1) == ERR) {
+		close (fd);
+		*status = XERR;
+		return (XERR);
+	    }
+	    lseek (fd, (off_t)0, 0);
+	}
+
+	/* For efficiency reasons the above is all we normally do.  However,
+	 * if ZFALOC is set in the environment we touch each file block at
+	 * least once in order to preallocate all the space at zfaloc time.
+	 * ZFALOC may optionally have a string value.  If no value is given
+	 * all files are match (zfaloc is fully allocate all files).
+	 * Otherwise, the string value is a comma delimited list of simple
+	 * pattern strings.  A file is matched, and space preallocated, if
+	 * the given substring appears anywhere in the file name.
+	 */
+	if ( (s = getenv ("ZFALOC")) ) {
+	    register char *ip, *op;
+	    char    patstr[SZ_PATHNAME];
+	    int     match = (*s == '\0');
+	    int     patlen, i;
+
+	    while (!match && *s) {
+		for (op=patstr;  *s && *s != ',';  )
+		    *op++ = *s++;
+		*op = '\0';
+		patlen = strlen (patstr);
+		if (*s == ',')
+		    s++;
+
+		for (ip=(char *)fname;  *ip;  ip++)
+		    if (*ip == patstr[0] && !strncmp(ip,patstr,patlen)) {
+			match++;
+			break;
+		    }
+	    }
+
+	    if (match)
+		for (i=0;  i < *nbytes;  i += 512) {
+		    lseek (fd, (off_t)i, 0);
+		    if (write (fd, &data, 1) < 0) {
+			*status = XERR;
+			close (fd);
+			return (XERR);
+		    }
+		}
+	}
+
+	close (fd);
+	*status = XOK;
+
+	return (XOK);
+}