com32/chain: minor fixes and cleanups

- make sure opt.maps implies opt.sect, and simplify
  conditions throughout the files
- move structure opt -> options.c
- adjust #includes
- omitted values in seg= and sect= are assumed 0
  in all cases now
- mangler_handover(): eax for gpt handover set only for
  iterated disks
- rename parse_args() -> opt_parse_args()
- rename mangler_common() -> mangler_init()
- add opt_set_defs()
- if mmapped sector would conflict with the file, turn
  off mmapping instead of bailing out
- update temporary chain.txt to reflect changes + other
  fixups

Signed-off-by: Michal Soltys <soltys@ziu.info>

7 files changed, 72 insertions, 60 deletions

diff --git a/com32/chain/chain.c b/com32/chain/chain.c
index 99eed0eb..f0d14971 100644
--- a/com32/chain/chain.c
+++ b/com32/chain/chain.c
@@ -41,8 +41,6 @@
 #include "partiter.h"
 #include "mangle.h"
 
-struct options opt;
-
 static int fixed_cnt = 128;   /* see comments in main() */
 
 static int overlap(const struct data_area *a, const struct data_area *b)
@@ -496,38 +494,28 @@ bail:
 int main(int argc, char *argv[])
 {
     struct part_iter *iter = NULL;
-
     void *sbck = NULL;
     struct data_area fdat, hdat, sdat, data[3];
     int ndata = 0;
 
     console_ansi_raw();
-/*    openconsole(&dev_null_r, &dev_stdcon_w);*/
 
-    /* Prepare and set defaults */
     memset(&fdat, 0, sizeof(fdat));
     memset(&hdat, 0, sizeof(hdat));
     memset(&sdat, 0, sizeof(sdat));
-    memset(&opt, 0, sizeof(opt));
-    opt.sect = true;	/* by def. load sector */
-    opt.maps = true;	/* by def. map sector */
-    opt.hand = true;	/* by def. prepare handover */
-    opt.chain = true;	/* by def. do chainload */
-    opt.foff = opt.soff = opt.fip = opt.sip = 0x7C00;
-    opt.drivename = "boot";
-#ifdef DEBUG
-    opt.warn = true;
-#endif
 
-    /* Parse arguments */
-    if (parse_args(argc, argv))
+    opt_set_defs();
+    if (opt_parse_args(argc, argv))
 	goto bail;
+
 #if 0
     /* Get max fixed disk number */
     fixed_cnt = *(uint8_t *)(0x475);
 
     /*
-     * hmm, looks like we can't do that
+     * hmm, looks like we can't do that -
+     * some bioses/vms just set it to 1
+     * and go on living happily
      * any better options than hardcoded 0x80 - 0xFF ?
      */
 #endif
@@ -563,21 +551,20 @@ int main(int argc, char *argv[])
 	    error("The sector cannot be loaded at such high address.\n");
 	    goto bail;
 	}
-	if (opt.file && opt.maps && overlap(&fdat, &sdat)) {
-	    error("WARNING: The sector won't be loaded, as it would conflict with the boot file.\n");
-	    opt.sect = false;
-	} else {
-	    if (!(sdat.data = disk_read_sectors(&iter->di, iter->start_lba, 1))) {
-		error("Couldn't read the sector.\n");
+	if (!(sdat.data = disk_read_sectors(&iter->di, iter->start_lba, 1))) {
+	    error("Couldn't read the sector.\n");
+	    goto bail;
+	}
+	if (opt.save) {
+	    if (!(sbck = malloc(sdat.size))) {
+		error("Couldn't allocate cmp-buf for option 'save'.\n");
 		goto bail;
 	    }
-	    if (opt.save) {
-		if (!(sbck = malloc(sdat.size))) {
-		    error("Couldn't allocate cmp-buf for option 'save'.\n");
-		    goto bail;
-		}
-		memcpy(sbck, sdat.data, sdat.size);
-	    }
+	    memcpy(sbck, sdat.data, sdat.size);
+	}
+	if (opt.file && opt.maps && overlap(&fdat, &sdat)) {
+	    error("WARNING: The sector won't be mmapped, as it would conflict with the boot file.\n");
+	    opt.maps = false;
 	}
     }
 
@@ -587,7 +574,7 @@ int main(int argc, char *argv[])
 	    goto bail;
 	/* Verify possible conflicts */
 	if ( ( opt.file && overlap(&fdat, &hdat)) ||
-	     ( opt.sect && overlap(&sdat, &hdat) && opt.maps) ) {
+	     ( opt.maps && overlap(&sdat, &hdat)) ) {
 	    error("WARNING: Handover area won't be prepared,\n"
 		  "as it would conflict with the boot file and/or the sector.\n");
 	    opt.hand = false;
@@ -596,7 +583,7 @@ int main(int argc, char *argv[])
 
     /* Adjust registers */
 
-    mangler_common(iter);
+    mangler_init(iter);
     mangler_handover(iter, &hdat);
     mangler_grldr(iter);
 
@@ -634,7 +621,7 @@ int main(int argc, char *argv[])
 
     if (opt.file)
 	memcpy(data + ndata++, &fdat, sizeof(fdat));
-    if (opt.sect && opt.maps)
+    if (opt.maps)
 	memcpy(data + ndata++, &sdat, sizeof(sdat));
     if (opt.hand)
 	memcpy(data + ndata++, &hdat, sizeof(hdat));
diff --git a/com32/chain/chain.h b/com32/chain/chain.h
index 67144753..fc481bc6 100644
--- a/com32/chain/chain.h
+++ b/com32/chain/chain.h
@@ -1,9 +1,7 @@
 #ifndef _COM32_CHAIN_CHAIN_H
 #define _COM32_CHAIN_CHAIN_H
 
-#include <stdint.h>
-#include <syslinux/bootrm.h>
-#include "options.h"
+#include <syslinux/movebits.h>
 
 struct data_area {
     void *data;
@@ -11,8 +9,6 @@ struct data_area {
     addr_t size;
 };
 
-extern struct options opt;
-
 #endif
 
 /* vim: set ts=8 sts=4 sw=4 noet: */
diff --git a/com32/chain/mangle.c b/com32/chain/mangle.c
index e4d4be36..c32cd5c8 100644
--- a/com32/chain/mangle.c
+++ b/com32/chain/mangle.c
@@ -392,7 +392,7 @@ int mangles_cmldr(struct data_area *data)
 }
 
 /* Set common registers */
-int mangler_common(const struct part_iter *iter)
+int mangler_init(const struct part_iter *iter)
 {
     /* Set initial registry values */
     if (opt.file) {
@@ -415,7 +415,7 @@ int mangler_common(const struct part_iter *iter)
 /* ds:si & ds:bp */
 int mangler_handover(const struct part_iter *iter, const struct data_area *data)
 {
-    if (opt.sect && opt.file && opt.maps && !opt.hptr) {
+    if (opt.file && opt.maps && !opt.hptr) {
 	opt.regs.esi.l = opt.regs.ebp.l = opt.soff;
 	opt.regs.ds = (uint16_t)opt.sseg;
 	opt.regs.eax.l = 0;
@@ -423,7 +423,7 @@ int mangler_handover(const struct part_iter *iter, const struct data_area *data)
 	/* base is really 0x7be */
 	opt.regs.esi.l = opt.regs.ebp.l = data->base;
 	opt.regs.ds = 0;
-	if (iter->type == typegpt)
+	if (iter->index && iter->type == typegpt)   /* must be iterated and GPT */
 	    opt.regs.eax.l = 0x54504721;	/* '!GPT' */
 	else
 	    opt.regs.eax.l = 0;
diff --git a/com32/chain/mangle.h b/com32/chain/mangle.h
index eff24b98..4e097933 100644
--- a/com32/chain/mangle.h
+++ b/com32/chain/mangle.h
@@ -4,21 +4,26 @@
 #include "chain.h"
 #include "partiter.h"
 
+/* file's manglers */
 int manglef_isolinux(struct data_area *data);
 int manglef_grub(const struct part_iter *iter, struct data_area *data);
 int manglef_bpb(const struct part_iter *iter, struct data_area *data);
 /* int manglef_drmk(struct data_area *data);*/
 
+/* sector's manglers */
 int mangles_bpb(const struct part_iter *iter, struct data_area *data);
 int mangles_save(const struct part_iter *iter, const struct data_area *data, void *org);
 int mangles_cmldr(struct data_area *data);
 
+/* sector + file's manglers */
 int manglesf_bss(struct data_area *sec, struct data_area *fil);
 
-int mangler_common(const struct part_iter *iter);
+/* registers' manglers */
+int mangler_init(const struct part_iter *iter);
 int mangler_handover(const struct part_iter *iter, const struct data_area *data);
 int mangler_grldr(const struct part_iter *iter);
 
+/* partition layout's manglers */
 int manglepe_mbrchshide(struct part_iter *miter);
 
 #endif
diff --git a/com32/chain/options.c b/com32/chain/options.c
index 37b9f114..288fe770 100644
--- a/com32/chain/options.c
+++ b/com32/chain/options.c
@@ -6,7 +6,9 @@
 #include "utility.h"
 #include "options.h"
 
-int soi_s2n(char *ptr, unsigned int *seg,
+struct options opt;
+
+static int soi_s2n(char *ptr, unsigned int *seg,
 		       unsigned int *off,
 		       unsigned int *ip,
 		       unsigned int def)
@@ -49,7 +51,7 @@ bail:
     return -1;
 }
 
-void usage(void)
+static void usage(void)
 {
     unsigned int i;
     static const char key[] = "Press any key...\n";
@@ -116,7 +118,21 @@ Usage:\n\
     }
 }
 
-int parse_args(int argc, char *argv[])
+void opt_set_defs(void)
+{
+    memset(&opt, 0, sizeof(opt));
+    opt.sect = true;	/* by def. load sector */
+    opt.maps = true;	/* by def. map sector */
+    opt.hand = true;	/* by def. prepare handover */
+    opt.chain = true;	/* by def. do chainload */
+    opt.foff = opt.soff = opt.fip = opt.sip = 0x7C00;
+    opt.drivename = "boot";
+#ifdef DEBUG
+    opt.warn = true;
+#endif
+}
+
+int opt_parse_args(int argc, char *argv[])
 {
     int i;
     unsigned int v;
@@ -250,12 +266,13 @@ int parse_args(int argc, char *argv[])
 	} else if (!strncmp(argv[i], "sect=", 5) ||
 		   !strcmp(argv[i], "sect")) {
 	    if (argv[i][4]) {
-		if (soi_s2n(argv[i] + 5, &opt.sseg, &opt.soff, &opt.sip, 0x7c00))
+		if (soi_s2n(argv[i] + 5, &opt.sseg, &opt.soff, &opt.sip, 0))
 		    goto bail;
 	    }
 	    opt.sect = true;
 	} else if (!strcmp(argv[i], "nosect")) {
 	    opt.sect = false;
+	    opt.maps = false;
 	} else if (!strcmp(argv[i], "save")) {
 	    opt.save = true;
 	} else if (!strcmp(argv[i], "nosave")) {
@@ -331,6 +348,11 @@ int parse_args(int argc, char *argv[])
 	goto bail;
     }
 
+    if (opt.maps && !opt.sect) {
+	error("Option 'maps' requires option 'sect'.\n");
+	goto bail;
+    }
+
     return 0;
 bail:
     return -1;
diff --git a/com32/chain/options.h b/com32/chain/options.h
index bc244f60..17c6a739 100644
--- a/com32/chain/options.h
+++ b/com32/chain/options.h
@@ -1,6 +1,9 @@
 #ifndef _COM32_CHAIN_OPTIONS_H
 #define _COM32_CHAIN_OPTIONS_H
 
+#include <stdint.h>
+#include <syslinux/bootrm.h>
+
 struct options {
     unsigned int fseg;
     unsigned int foff;
@@ -34,10 +37,10 @@ struct options {
     struct syslinux_rm_regs regs;
 };
 
-int soi_s2n(char *ptr, unsigned int *seg, unsigned int *off,
-	unsigned int *ip, unsigned int def);
-void usage(void);
-int parse_args(int argc, char *argv[]);
+extern struct options opt;
+
+void opt_set_defs(void);
+int opt_parse_args(int argc, char *argv[]);
 
 #endif
 
diff --git a/doc/chain.txt b/doc/chain.txt
index c5086515..26243100 100644
--- a/doc/chain.txt
+++ b/doc/chain.txt
@@ -40,7 +40,7 @@ A "service-only" run is possible when either:
 
 or
 
-- 'nofile' and 'nomaps' are in effect
+- 'nofile' and 'nomaps' (or 'nosect') are in effect
 
 This is useful for invocations such as:
 
@@ -117,6 +117,7 @@ If any of the fields are ommited (e.g. 0x2000::), they default to 0.
 	sect=<segment>:<offset>:<ip>
 	nosect
 	*sect=0:0x7c00:0x7c00
+	nosect sets: nomaps
 
 This triplet lets you alter the addresses a sector will use. File is loaded at
 <segment:offset>, the jump is made to <segment:ip>. This option is mostly used
@@ -127,8 +128,7 @@ relocated sector at some particular address (e.g. DRKM).
 is being chainloaded, sector is not necessary.
 
 The defaults if option is not specified, are 0:0x7c00:0x7c00.
-If some of the fields are ommited (e.g. 0x2000::), segment defaults to 0,
-offset and ip to 0x7c00.
+If some of the fields are ommited (e.g. 0x2000::), they default to 0.
 
 	*maps
 	nomaps
@@ -172,16 +172,15 @@ together with 'setbpb' or other ones using that implicitly.
 
 - this option never applies to a loaded file
 - chain module will never save anything to disk by default
-- writing is only performed, if the values actually got changed
+- writing is only performed, if the values actually changed
 
 	*hand
 	nohand
 
-By default, a handover area is always prepared if possible and potentially
-useful - meaning it doesn't overlap with other areas, and syslinux chainloads a
-partition. It's often not necessary though - usually, a chainloaded file or
-kernel don't care about it anymore, so a user can disable it explicitly with
-this option.
+By default, a handover area is always prepared if possible - meaning it doesn't
+overlap with other areas. It's often not necessary though - usually, a
+chainloaded file or kernel don't care about it anymore, so a user can disable
+it explicitly with this option.
 
 	hptr
 	*nohptr