Init

sys/boot/os/readfile.c

@@ -0,0 +1,101 @@
+/*
+ * @(#)readfile.c 1.1 94/10/31 Copyright (c) 1985 by Sun Microsystems, Inc.
+ */
+
+#include <stand/saio.h>
+#include <a.out.h>
+
+/*
+ * Read in a Unix executable file and return its entry point.
+ * Handle the various a.out formats correctly.
+ * "Io" is the standalone file descriptor to read from.
+ * Print informative little messages if "print" is on.
+ * Returns -1 for errors.
+ *
+ * The parameter <LOAD> must be set in the command line to cc, e.g.
+ * 	cc -DLOAD=0x4000 -o readfile.c
+ * The makefile takes care of this.
+ */
+int (*
+readfile(io, print))()
+	register int io;
+	int print;
+{
+	struct exec x;
+	register int i;
+	register char *addr;
+	register int shared = 0;
+	register int loadaddr;
+	register int segsiz;
+	register int datasize;
+	extern char start[];
+
+	i = read(io, (char *)&x, sizeof x);
+	if (x.a_magic == ZMAGIC || x.a_magic == NMAGIC)
+		shared = 1;
+	if (i != sizeof x || (!shared && x.a_magic != OMAGIC)) {
+		printf("Not executable\n");
+		return ((int (*)()) -1);
+	}
+	if (print)
+		printf("Size: %d", x.a_text);
+	datasize = x.a_data;
+	if (!shared) {
+		x.a_text = x.a_text + x.a_data;
+		x.a_data = 0;
+	}
+	if (lseek(io, N_TXTOFF(x), 0) == -1)
+		goto shread;
+	addr = (char *)(x.a_text + LOAD);
+	if (addr  > (char *)start) {
+		printf("\nProgram text overlaps boot code! 0x%x > 0x%x\n",
+			addr, start);
+		goto shread;
+	}
+#ifdef	NFS_BOOT
+#define	FUDGE	(0x2000-0x20)
+	if (read(io, (char *)LOAD, FUDGE) != FUDGE)
+		goto shread;
+	if (read(io, (char *)(LOAD+FUDGE), (int)x.a_text-FUDGE) !=
+		(x.a_text-FUDGE))
+		goto shread;
+#else
+	if (read(io, (char *)LOAD, (int)x.a_text) != x.a_text)
+		goto shread;
+#endif NFS_BOOT
+	if (x.a_machtype == M_OLDSUN2)
+		segsiz = OLD_SEGSIZ;
+	else
+		segsiz = SEGSIZ;
+	if (shared)
+		while ((int)addr & (segsiz-1))
+			*addr++ = 0;
+	if (addr + x.a_data > (char *)start) {
+		printf("\nProgram data overlaps boot code!\n");
+		goto shread;
+	}
+	if (print)
+		printf("+%d", datasize);
+
+	if ((int)x.a_data != 0)		/* Avoid zero length read */
+		if (read(io, addr, (int)x.a_data) < x.a_data)
+			goto shread;
+
+	close(io);		/* Done with it. */
+	if (print)
+		printf("+%d", x.a_bss);
+	addr += x.a_data;
+	for (i = 0; i < x.a_bss && addr < (char *)start; i++)
+		*addr++ = 0;
+	if (print)
+		printf(" bytes\n");
+	if (x.a_machtype != M_OLDSUN2 && x.a_magic == ZMAGIC)
+		loadaddr = LOAD + sizeof (struct exec);
+	else
+		loadaddr = LOAD;
+	return (int (*)()) (loadaddr);
+
+shread:
+	printf("Truncated file\n");
+	return ((int (*)()) -1);
+}