Add boot from other volumes in bootloader on targets with HAVE_MULTIVOLUME

Adds the ability to load firmware from other drives on MULTIVOLUME targets
Mihail Zenkov <mihail.zenkov@gmail.com> had posted a hard coded patch
to allow this on several Sansa players, I made it more universal

Redirect file rockbox_main.<name> should placed in root of
drive you would like to be main, if this file empty or there a single
slash '/' firmware will be loaded from /.rockbox in root of this drive
If instead a /<*DIRECTORY*> is supplied in rockbox_main.<name> then
firmware will be loaded from /<dir>/.rockbox/

NOTES*

The directory can have multiple levels however..
leading slash MUST be included
trailing slash can be omitted
(eg. /test/.rockbox would be simply '/test' in the redirect file)

Redirect file will not work on internal drive (whatever is default boot drive)

Volume with the highest index containing redirect file will be loaded
first.

Firmware file is checked for boot data region, if missing, firmware
image will not be loaded.

On failure or if no redirect file is found load will fallback to
internal drive

Currently only Sansa Fuze+, Sansa Clip+,
Sansa Clip Zip, Sansa Fuzev2, and Sansa Fuzev1 are implemented.

Players (with HAVE_MULTIVOLUME)
will need #define HAVE_BOOTDATA and #define BOOT_REDIR "rockbox_main.<name>"
added to their config file

boot_data is implemented in crt0.s file (See g#1552)
ARM and IMX233 have aleady been implemented

Once these conditions are met <HAVE_MULTIBOOT> will be defined by config.h

Partitions on the drives are able to have a redirect as
well.

Change-Id: Iada3263919f6bcad7d0d7d8279b4239aafa07ee9

8 files changed, 167 insertions, 59 deletions

diff --git a/firmware/common/rb-loader.c b/firmware/common/rb-loader.c
index 82b636d451..8bf553a3a8 100644
--- a/firmware/common/rb-loader.c
+++ b/firmware/common/rb-loader.c
@@ -7,6 +7,7 @@
  *                     \/            \/     \/    \/            \/
  *
  * Copyright (C) 2005 by Linus Nielsen Feltzing
+ * Copyright (C) 2017 by William Wilgus
  *
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of the GNU General Public License
@@ -22,18 +23,16 @@
 #include "config.h"
 #include "system.h"
 #include "file.h"
-#include "rb-loader.h"
 #include "loader_strerror.h"
 
 #if defined(HAVE_BOOTDATA)
 #include "bootdata.h"
 #include "crc32.h"
 
-/* Write boot data into location marked by magic header
- * buffer is already loaded with the firmware image
- * we just need to find the location and write
- * data into the payload along with the crc
- * for later verification and use.
+/* Write bootdata into location in FIRMWARE marked by magic header
+ * Assumes buffer is already loaded with the firmware image
+ * We just need to find the location and write data into the
+ * payload region along with the crc for later verification and use.
  * Returns payload len on success,
  * On error returns EKEY_NOT_FOUND
  */
@@ -51,68 +50,92 @@ static int write_bootdata(unsigned char* buf, int len, unsigned int boot_volume)
         if (fw_boot_data->magic[0] != BOOT_DATA_MAGIC0 ||
             fw_boot_data->magic[1] != BOOT_DATA_MAGIC1)
             continue;
-        /* 0 fill bootloader struct then add our data */
+
         memset(&bl_boot_data.payload, 0, BOOT_DATA_PAYLOAD_SIZE);
         bl_boot_data.boot_volume = boot_volume;
-        /* 0 fill payload region in firmware */
+
         memset(fw_boot_data->payload, 0, fw_boot_data->length);
         /* determine maximum bytes we can write to firmware
            BOOT_DATA_PAYLOAD_SIZE is the size the bootloader expects */
         payload_len = MIN(BOOT_DATA_PAYLOAD_SIZE, fw_boot_data->length);
-        /* write payload size back to firmware struct */
         fw_boot_data->length = payload_len;
-        /* copy data to firmware bootdata struct */
+        /* copy data to FIRMWARE bootdata struct */
         memcpy(fw_boot_data->payload, &bl_boot_data.payload, payload_len);
-        /* calculate and write the crc for the payload */
-        fw_boot_data->crc = crc_32(fw_boot_data->payload,
-                                   payload_len,
-                                   0xffffffff);
+        /* crc will be used within the firmware to check validity of bootdata */
+        fw_boot_data->crc = crc_32(fw_boot_data->payload, payload_len, 0xffffffff);
         break;
 
     }
     return payload_len;
 }
 #endif /* HAVE_BOOTDATA */
-/* Load firmware image in a format created by add method of tools/scramble
- * on success we return size loaded image
- * on error we return negative value which can be deciphered by means
- * of strerror() function
+
+#ifdef HAVE_MULTIBOOT /* defined by config.h */
+/* Check in root of this <volume> for rockbox_main.<playername>
+ * if this file empty or there is a single slash '/'
+ * buf = '<volume#>/<rootdir>/<firmware(name)>\0'
+ * If instead '/<*DIRECTORY*>' is supplied
+ * addpath will be set to this DIRECTORY buf =
+ * '/<volume#>/addpath/<rootdir>/<firmware(name)>\0'
+ * On error returns Negative number or 0
+ * On success returns bytes from snprintf
+ * and generated path will be placed in buf
+ * note: if supplied buffer is too small return will be
+ * the number of bytes that would have been written
  */
-int load_firmware(unsigned char* buf, const char* firmware, int buffer_size)
+int get_redirect_dir(char* buf, int buffer_size, int volume,
+                     const char* rootdir, const char* firmware)
 {
-    char filename[MAX_PATH];
     int fd;
-    int rc;
-    int len;
-    int ret = 0;
-    unsigned long chksum;
-    unsigned long sum;
-    int i;
-
-    /* only filename passed */
-    if (firmware[0] != '/')
-    {
-        /* First check in BOOTDIR */
-        snprintf(filename, sizeof(filename), BOOTDIR "/%s",firmware);
-
-        fd = open(filename, O_RDONLY);
-        if(fd < 0)
-        {
-            /* Check in root dir */
-            snprintf(filename, sizeof(filename),"/%s",firmware);
-            fd = open(filename, O_RDONLY);
+    int f_offset;
+    char add_path[MAX_PATH];
+    /* Check in root of volume for rockbox_main.<playername> redirect */
+    snprintf(add_path, sizeof(add_path), "/<%d>/"BOOT_REDIR, volume);
+    fd = open(add_path, O_RDONLY);
+    if (fd < 0)
+        return EFILE_NOT_FOUND;
+
+    /*clear add_path for re-use*/
+    memset(add_path, 0, sizeof(add_path));
+    f_offset = read(fd, add_path,sizeof(add_path));
+    close(fd);
 
-            if (fd < 0)
-                return EFILE_NOT_FOUND;
-        }
-    }
-    else
+    for(int i = f_offset - 1;i > 0; i--)
     {
-        /* full path passed */
-        fd = open(firmware, O_RDONLY);
-        if (fd < 0)
-            return EFILE_NOT_FOUND;
+        /* strip control chars < SPACE or all if path doesn't start with '/' */
+        if (add_path[i] < 0x20 || add_path[0] != '/')
+           add_path[i] = '\0';
     }
+    /* if '/add_path' is specified in rockbox_main.<playername>
+       path is /<vol#>/add_path/rootdir/firmwarename
+       if add_path is empty or '/' is missing from beginning
+       path is /<vol#>/rootdir/firmwarename
+    */
+    return snprintf(buf, buffer_size, "/<%d>%s/%s/%s", volume, add_path,
+                                                        rootdir, firmware);
+}
+#endif /* HAVE_MULTIBOOT */
+
+/* loads a firmware file from supplied filename
+ * file opened, checks firmware size and checksum
+ * if no error, firmware loaded to supplied buffer
+ * file closed
+ * Returns size of loaded image on success
+ * On error returns Negative value deciphered by means
+ * of strerror() function
+ */
+static int load_firmware_filename(unsigned char* buf,
+                                  const char* filename,
+                                  int buffer_size)
+{
+    int len;
+    unsigned long chksum, sum;
+    int i;
+    int ret;
+    int fd = open(filename, O_RDONLY);
+
+    if (fd < 0)
+        return EFILE_NOT_FOUND;
 
     len = filesize(fd) - 8;
 
@@ -124,18 +147,16 @@ int load_firmware(unsigned char* buf, const char* firmware, int buffer_size)
 
     lseek(fd, FIRMWARE_OFFSET_FILE_CRC, SEEK_SET);
 
-    rc = read(fd, &chksum, 4);
-    chksum = betoh32(chksum); /* Rockbox checksums are big-endian */
-    if(rc < 4)
+    if (read(fd, &chksum, 4) < 4)
     {
         ret = EREAD_CHKSUM_FAILED;
         goto end;
     }
+    chksum = betoh32(chksum); /* Rockbox checksums are big-endian */
 
     lseek(fd, FIRMWARE_OFFSET_FILE_DATA, SEEK_SET);
 
-    rc = read(fd, buf, len);
-    if(rc < len)
+    if (read(fd, buf, len) < len)
     {
         ret = EREAD_IMAGE_FAILED;
         goto end;
@@ -148,19 +169,72 @@ int load_firmware(unsigned char* buf, const char* firmware, int buffer_size)
         sum += buf[i];
     }
 
-    if(sum != chksum)
+    if (sum != chksum)
     {
         ret = EBAD_CHKSUM;
         goto end;
     }
-#ifdef HAVE_BOOTDATA
-    /* 0 is the default boot volume */
-    write_bootdata(buf, ret, 0);
-#endif
     ret = len;
 
-
 end:
     close(fd);
     return ret;
 }
+
+/* Load firmware image in a format created by add method of tools/scramble
+ * on success we return size loaded image
+ * on error we return negative value which can be deciphered by means
+ * of strerror() function
+ */
+int load_firmware(unsigned char* buf, const char* firmware, int buffer_size)
+{
+
+    int ret = EFILE_NOT_FOUND;
+    char filename[MAX_PATH+2];
+    /* only filename passed */
+    if (firmware[0] != '/')
+    {
+
+#ifdef HAVE_MULTIBOOT /* defined by config.h */
+        /* checks <volumes> highest index to lowest for redirect file
+         * 0 is the default boot volume, it is not checked here
+         * if found <volume>/rockbox_main.<playername> and firmware
+         * has a bootdata region this firmware will be loaded */
+        for (unsigned int i = NUM_VOLUMES - 1; i > 0 && ret < 0; i--)
+        {
+            if (get_redirect_dir(filename, sizeof(filename), i,
+                                 BOOTDIR, firmware) > 0)
+            {
+                ret = load_firmware_filename(buf, filename, buffer_size);
+            /* if firmware has no boot_data don't load from external drive */
+                if (write_bootdata(buf, ret, i) <= 0)
+                    ret = EKEY_NOT_FOUND;
+            }
+            /* if ret is valid breaks from loop to continue loading */
+        }
+#endif
+
+        if (ret < 0) /* Check default volume, no valid firmware file loaded yet */
+        {
+            /* First check in BOOTDIR */
+            snprintf(filename, sizeof(filename), BOOTDIR "/%s",firmware);
+
+            ret = load_firmware_filename(buf, filename, buffer_size);
+
+            if (ret < 0)
+            {
+                /* Check in root dir */
+                snprintf(filename, sizeof(filename),"/%s",firmware);
+                ret = load_firmware_filename(buf, filename, buffer_size);
+            }
+#ifdef HAVE_BOOTDATA
+                /* 0 is the default boot volume */
+                write_bootdata(buf, ret, 0);
+#endif
+        }
+    }
+    else /* full path passed ROLO etc.*/
+        ret = load_firmware_filename(buf, firmware, buffer_size);
+
+    return ret;
+}
diff --git a/firmware/export/config.h b/firmware/export/config.h
index 51e0f7a17b..475bd573d4 100644
--- a/firmware/export/config.h
+++ b/firmware/export/config.h
@@ -859,6 +859,11 @@ Lyre prototype 1 */
 #error HAVE_MULTIDRIVE needs to have an explicit NUM_DRIVES
 #endif
 
+/* note to remove multi-partition booting this could be changed to MULTIDRIVE */
+#if defined(HAVE_BOOTDATA) && defined(BOOT_REDIR) && defined(HAVE_MULTIVOLUME)
+#define HAVE_MULTIBOOT
+#endif
+
 #ifndef NUM_DRIVES
 #define NUM_DRIVES 1
 #endif
diff --git a/firmware/export/config/sansaclipplus.h b/firmware/export/config/sansaclipplus.h
index cf2b1136a3..addf7d86c0 100644
--- a/firmware/export/config/sansaclipplus.h
+++ b/firmware/export/config/sansaclipplus.h
@@ -9,6 +9,8 @@
 #define FIRMWARE_OFFSET_FILE_CRC 0
 /* Define if boot data from bootloader has been enabled for the target */
 #define HAVE_BOOTDATA
+/* define boot redirect file name allows booting from external drives */
+#define BOOT_REDIR "rockbox_main.clip+"
 
 #define HAVE_MULTIDRIVE
 #define NUM_DRIVES 2
diff --git a/firmware/export/config/sansaclipzip.h b/firmware/export/config/sansaclipzip.h
index 9f1ff1f206..fc9f558eef 100644
--- a/firmware/export/config/sansaclipzip.h
+++ b/firmware/export/config/sansaclipzip.h
@@ -9,6 +9,8 @@
 #define FIRMWARE_OFFSET_FILE_CRC 0
 /* Define if boot data from bootloader has been enabled for the target */
 #define HAVE_BOOTDATA
+/* define boot redirect file name allows booting from external drives */
+#define BOOT_REDIR "rockbox_main.clipzip"
 
 #define HAVE_MULTIDRIVE
 #define NUM_DRIVES 2
diff --git a/firmware/export/config/sansafuze.h b/firmware/export/config/sansafuze.h
index d674d1f88a..fae3463d75 100644
--- a/firmware/export/config/sansafuze.h
+++ b/firmware/export/config/sansafuze.h
@@ -8,6 +8,9 @@
 /* Define if boot data from bootloader has been enabled for the target */
 #define HAVE_BOOTDATA
 
+/* define boot redirect file name allows booting from external drives */
+#define BOOT_REDIR "rockbox_main.fuze"
+
 #define HW_SAMPR_CAPS       SAMPR_CAP_ALL
 
 /* define this if you have recording possibility */
diff --git a/firmware/export/config/sansafuzeplus.h b/firmware/export/config/sansafuzeplus.h
index af5235a6c3..2a57619b06 100644
--- a/firmware/export/config/sansafuzeplus.h
+++ b/firmware/export/config/sansafuzeplus.h
@@ -10,6 +10,8 @@
 #define MODEL_NAME   "Sandisk Sansa Fuze+"
 /* Define if boot data from bootloader has been enabled for the target */
 #define HAVE_BOOTDATA
+/* define boot redirect file name allows booting from external drives */
+#define BOOT_REDIR "rockbox_main.fuze+"
 
 #define HW_SAMPR_CAPS       SAMPR_CAP_ALL
 
diff --git a/firmware/export/config/sansafuzev2.h b/firmware/export/config/sansafuzev2.h
index a4d90160bd..b85e0747a3 100644
--- a/firmware/export/config/sansafuzev2.h
+++ b/firmware/export/config/sansafuzev2.h
@@ -8,6 +8,9 @@
 /* Define if boot data from bootloader has been enabled for the target */
 #define HAVE_BOOTDATA
 
+/* define boot redirect file name allows booting from external drives */
+#define BOOT_REDIR "rockbox_main.fuze2"
+
 #define HW_SAMPR_CAPS       SAMPR_CAP_ALL
 
 /* define this if you have recording possibility */
diff --git a/firmware/include/rb-loader.h b/firmware/include/rb-loader.h
index 86c5026af9..71b6e038aa 100644
--- a/firmware/include/rb-loader.h
+++ b/firmware/include/rb-loader.h
@@ -19,3 +19,20 @@
  ****************************************************************************/
 
 int load_firmware(unsigned char* buf, const char* firmware, int buffer_size);
+
+#ifdef HAVE_MULTIBOOT /* defined by config.h */
+/* Check in root of this <volume> for rockbox_main.<playername>
+ * if this file empty or there is a single slash '/'
+ * buf = '<volume#>/<rootdir>/<firmware(name)>\0'
+ * If instead '/<*DIRECTORY*>' is supplied
+ * addpath will be set to this DIRECTORY buf =
+ * '/<volume#>/addpath/<rootdir>/<firmware(name)>\0'
+ * On error returns Negative number or 0
+ * On success returns bytes from snprintf
+ * and generated path will be placed in buf
+ * note: if supplied buffer is too small return will be
+ * the number of bytes that would have been written
+ */
+int get_redirect_dir(char* buf, int buffer_size, int volume,
+                     const char* rootdir, const char* firmware);
+#endif