From b0574dee64f9c86a6e3a93e3044f7711a9363dd9 Mon Sep 17 00:00:00 2001
From: okuji <okuji@localhost>
Date: Sun, 20 Feb 2000 05:27:14 +0000
Subject: [PATCH] add a new command, cmp, and fix a bug in fat_mount.

---
 ChangeLog         |  9 +++++
 NEWS              |  1 +
 stage2/builtins.c | 90 +++++++++++++++++++++++++++++++++++++++++++++++
 stage2/fsys_fat.c | 19 ++++++----
 4 files changed, 112 insertions(+), 7 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 307cd0052..dad635729 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,12 @@
+2000-02-19  OKUJI Yoshinori  <okuji@gnu.org>
+
+	* stage2/builtins.c (cmp_func): New function.
+	(builtin_cmp): New variable.
+	(builtin_table): Added a pointer to BUILTIN_CMP.
+
+	* stage2/fsys_fat.c (fat_mount): Check if BPB.SECTS_PER_CLUST is
+	zero after reading the BPB to avoid zero division.
+	
 2000-02-18  OKUJI Yoshinori  <okuji@gnu.org>
 
 	* stage2/disk_io.c [!STAGE1_5] (make_saved_active): Make sure
diff --git a/NEWS b/NEWS
index 343bc313a..1c617700b 100644
--- a/NEWS
+++ b/NEWS
@@ -41,6 +41,7 @@ New in 0.5.94:
 * New commands "bootp", "dhcp" and "rarp" can be used to initialize a
   network device and get IP addresses from a network.
 * Long filename support in the FAT filesystem is added.
+* The command "cmp" compares each bytes in two files.
 
 New in 0.5.93 - 1999-10-30:
 * ELF format of FreeBSD kernel is supported.
diff --git a/stage2/builtins.c b/stage2/builtins.c
index 590599116..a93040588 100644
--- a/stage2/builtins.c
+++ b/stage2/builtins.c
@@ -377,6 +377,95 @@ static struct builtin builtin_chainloader =
   " forcibly, whether the boot loader signature is present or not."
 };
 
+
+/* This function could be used to debug new filesystem code. Put a file
+   in the new filesystem and the same file in a well-tested filesystem.
+   Then, run "cmp" with the files. If no output is obtained, probably
+   the code is good, otherwise investigate what's wrong...  */
+/* cmp FILE1 FILE2 */
+static int
+cmp_func (char *arg, int flags)
+{
+  /* The filenames.  */
+  char *file1, *file2;
+  /* The addresses.  */
+  char *addr1, *addr2;
+  int i;
+  /* The size of the file.  */
+  int size;
+
+  /* Get the filenames from ARG.  */
+  file1 = arg;
+  file2 = skip_to (0, arg);
+  if (! *file1 || ! *file2)
+    {
+      errnum = ERR_BAD_ARGUMENT;
+      return 1;
+    }
+
+  /* Terminate the filenames for convenience.  */
+  nul_terminate (file1);
+  nul_terminate (file2);
+
+  /* Read the whole data from FILE1.  */
+  addr1 = (char *) RAW_ADDR (0x100000);
+  if (! grub_open (file1))
+    return 1;
+  
+  /* Get the size.  */
+  size = filemax;
+  if (grub_read (addr1, -1) != size)
+    {
+      grub_close ();
+      return 1;
+    }
+  
+  grub_close ();
+
+  /* Read the whole data from FILE2.  */
+  addr2 = addr1 + size;
+  if (! grub_open (file2))
+    return 1;
+
+  /* Check if the size of FILE2 is equal to the one of FILE2.  */
+  if (size != filemax)
+    {
+      grub_printf ("Differ in size: 0x%x [%s], 0x%x [%s]\n",
+		   size, file1, filemax, file2);
+      grub_close ();
+      return 0;
+    }
+  
+  if (! grub_read (addr2, -1))
+    {
+      grub_close ();
+      return 1;
+    }
+  
+  grub_close ();
+
+  /* Now compare ADDR1 with ADDR2.  */
+  for (i = 0; i < size; i++)
+    {
+      if (addr1[i] != addr2[i])
+	grub_printf ("Differ at the offset %d: 0x%x [%s], 0x%x [%s]\n",
+		     i, (unsigned) addr1[i], file1,
+		     (unsigned) addr2[i], file2);
+    }
+  
+  return 0;
+}
+
+static struct builtin builtin_cmp =
+{
+  "cmp",
+  cmp_func,
+  BUILTIN_CMDLINE,
+  "cmp FILE1 FILE2",
+  "Compare the file FILE1 with the FILE2 and inform the different values"
+  " if any."
+};
+
 
 /* color */
 /* Set new colors used for the menu interface. Support two methods to
@@ -2839,6 +2928,7 @@ struct builtin *builtin_table[] =
   &builtin_bootp,
   &builtin_cat,
   &builtin_chainloader,
+  &builtin_cmp,
   &builtin_color,
   &builtin_configfile,
   &builtin_debug,
diff --git a/stage2/fsys_fat.c b/stage2/fsys_fat.c
index 7c1be888f..8aecaf298 100644
--- a/stage2/fsys_fat.c
+++ b/stage2/fsys_fat.c
@@ -67,22 +67,27 @@ fat_mount (void)
     return 0;
   
   /* Read bpb */
-  if (!devread (0, 0, sizeof(bpb), (char *) &bpb))
+  if (! devread (0, 0, sizeof (bpb), (char *) &bpb))
+    return 0;
+
+  /* Check if the number of sectors per cluster is zero here, to avoid
+     zero division.  */
+  if (bpb.sects_per_clust == 0)
     return 0;
   
-  for (i = 0; (1 << i) < FAT_CVT_U16(bpb.bytes_per_sect); i++)
-    {}
+  for (i = 0; (1 << i) < FAT_CVT_U16 (bpb.bytes_per_sect); i++)
+    ;
   FAT_SUPER->sectsize_bits = i;
   for (i = 0; (1 << i) < bpb.sects_per_clust; i++)
-    {}
+    ;
   FAT_SUPER->clustsize_bits = FAT_SUPER->sectsize_bits + i;
   
   /* Fill in info about super block */
-  FAT_SUPER->num_sectors = FAT_CVT_U16(bpb.short_sectors) 
-    ? FAT_CVT_U16(bpb.short_sectors) : bpb.long_sectors;
+  FAT_SUPER->num_sectors = FAT_CVT_U16 (bpb.short_sectors) 
+    ? FAT_CVT_U16 (bpb.short_sectors) : bpb.long_sectors;
   
   /* FAT offset and length */
-  FAT_SUPER->fat_offset = FAT_CVT_U16(bpb.reserved_sects);
+  FAT_SUPER->fat_offset = FAT_CVT_U16 (bpb.reserved_sects);
   FAT_SUPER->fat_length = 
     bpb.fat_length ? bpb.fat_length : bpb.fat32_length;