MFC various libsa fixes: r337037-r337039, r337065, r337412-r337413, r337874,
r338535, r338540, r339651, r339992-r339993, r340026

r337037:
libsa: pointer differs in signedness

A small cleanup, fix the argument type and while there, replace (char *)0 with
NULL.

r337038:
libsa: bootp is using pointers with different sign

Just change bp_file to char and same for variable s.

r337039:
libsa: assignment to char * from u_char *

Cast to char * instead of u_char *

r337065:
libsa: dereferencing type-punned pointer in cd9660

The warning is given by gcc build, but it is good to fix anyhow.
use bcopy instead of direct assignment.

r337412:
libsa: dos_checksum() should take unsigned chars

Fix pointers to integers with different sign issue.

r337413:
libsa: gzipfs.c converts pointers to integer types with different sign

Signed versus unsigned char.

r337874:
libsa: zfs_probe() needs to set spa to NULL

Silence the warning about possibly uninitialized use of spa.

r338535:
libsa: memory leak in tftp_open()

tftpfile is allocated just above and needs to be freed.

r338540:
libsa: validate tftp_makereq() after we did reset the read

The name check referred in the comment is not the only possible error source,
we need to validate the result.

r339651:
libsa: re-send ACK for older data packets in tftp

In current tftp code we drop out-of-order packets; however, we should play
nice and re-send ACK for older data packets we are receiving. This will
hopefully stop server repeating those packets we already have received.
Note we do not answer duplicates from "previous" session (that is, session
with different port number), those will eventually time out.

r339992:
libsa: tftp should not read past file end

When we have the file size via tsize option, use it to make sure we
will not attempt to read past file end.

r339993:
libsa: tftp should use calloc

instead of malloc() memset(), use calloc().

r340026:
libsa: cstyle cleanup tftp.c

No functinal changes intended.

MFC r304850, r305480, r324550-r324551, r324655, r324684: correct mis-merge

Some of these commits were improperly MFC'd in the sys/boot => stand
mega-MFC, others were simply missed. Correct that mistake now by manually
merging the few that were missed and record-only merge on the others.

r304850:
Unused variables and cstyle fix for loader dosfs

r305480:
Renumber the advertising clause.

r324550:
Add $FreeBSD$ to ancient sources that it's missing from.

r324551:
Move lib/libstand to sys/boot/libsa

Move the sources to sys/boot. Make adjustments related to the
move. Kill LIBSTAND_SRC since it's no longer needed.

r324655:
Remove the libstand directory which is now empty.

r324684:
Remove lib/libstand again, accidentally readded in r324683

MFC r325834,r325997,326502: Move sys/boot to stand/

This is effectively a direct commit to stable/11, due to differences between
stable/11 and head. Changes to DTS in sys/boot/fdt/dts were often
accompanied by kernel changes. Many of these were also risc-v updates that
likely had many more dependencies to MFC.

Because of this, sys/boot/fdt/dts remains as-is while everything else in
sys/boot relocates to stand/.

r325834: Move sys/boot to stand. Fix all references to new location

r325997: Remove empty directories.

r326502: Document the sys/boot -> stand move in hier.7 and the top-level README.

MFC r324551: Move lib/libstand to sys/boot/libsa

MFC Loader Fixes 2017q2: r316437,r316577,r316578,r316585,r316590,r316612,
r316625,r316628,r316654,r316682,r316704,r316771,r317092,r317097,r317099,
r317652,r317785,r317886,r317887,r318142,r318320,r318356,r318678,r318754,
r318982,r318986,r318987,r318988,r318989,r318990,r318991,r318992,r318993,
r318994,r318999,r319083,r319084,r319085,r320011,r320234,r320288,r320304,
r320467,r320482

r316437: Small cleanup to make i386/loader match efi/loader boot environment
code

r316577: loader: part.c cstyle cleanup

r316578: loader: want mechanism to avoid RA with bcache

r316585: loader: zfs reader should check all labels

r316590: libstand/dosfs: cache FAT32 in 128 Kb blocks to save loader memory

r316612: In r298230 the value of HEAP_MIN was changed from 3MB to 64MB.
Correct a comment.

r316625: Do not use -msoft-float with intention of disabling FP on aarch64

r316628: Silence GCC warning by initializing the local variable.

r316654: loader: r316585 did miss userboot update

r316682: loader: r316585 did miss sparc/ofw

r316704: loader.efi: only fetch zfs pool guid for the actual boot device

r316771: loader: Avoid possible overflow via environment variable

r317092: loader: zfs reader vdev_probe should check for minimum device size

r317097: loader: F_READ/F_WRITE should be checked against masked flag

r317099: loader: uboot disk ioctl should call disk_ioctl

r317652: loader.efi: ResetSystem does not use data with EFI_SUCCESS

r317785: zfsboot: drvsize() may be unusable on some systems

r317886: distinguish NFS versus TFTP boot by rootpath

r317887: loader: network read rework

r318142: libstand: NULL pointer dereference in rarp

r318320: loader: add ip layer code into libstand

r318356: libstand: increase nfs max read size to 16k

r318678: Replacing iterating over rootpath by strsep(3).

r318754: Pass -N directly to ld via -Wl rather than passing it to the
compiler driver.

r318982: Pass a "FREEBSD" user-class in PXE dhcp request

r318986: add a comment on vendor index 19 and 20 to avoid confusion

r318987: Support URI scheme for root-path in netbooting

r318988: Always build tftpfs support along with nfs for pxeboot

r318989: Always issue the pxe request

r318990: Partially revert r314948

r318991: Document recent changes on pxeboot

r318992: Capitalize DHCP

r318993: Use the usual FreeBSD spelling for the DHCP user class

r318994: Catch with the change in the user class

r318999: Update the comments concerning net_parse_rootpath to reflect what
it is now

r319083: Followup on the user-class changes

r319084: Small cleanup in dev_net.c

r319085: use the same option list for dhcp discovery and request

r320011: Add chain loader support for loader

r320234: Make structure padding explicit in EFI_MEMORY_DESCRIPTOR

r320288: Allow Clang's integrated assembler to assemble boot0

r320304: loader.efi: Disable smbios for arm

r320467: loader: chain load relocate data declaration is bad

r320482: As with arm64 mark the EFI PE header as allocated on arm.

PR: 218473

MFC r309369,310850,310853:

libstand: dosfs cstyle cleanup for return keyword.
dosfs support in libstand is broken since r298230

PR: 214423
Submitted by: Mikhail Kupchik
Reported by: Mikhail Kupchik
Approved by: imp (mentor)

Copy head@r302406 to stable/11 as part of the 11.0-RELEASE cycle.
Prune svn:mergeinfo from the new branch, as nothing has been merged
here.

Additional commits post-branch will follow.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

A new implementation of the loader block cache

The block cache implementation in loader has proven to be almost useless, and in worst case even slowing down the disk reads due to insufficient cache size and extra memory copy.
Also the current cache implementation does not cache reads from CDs, or work with zfs built on top of multiple disks.
Instead of an LRU, this code uses a simple hash (O(1) read from cache), and instead of a single global cache, a separate cache per block device.
The cache also implements limited read-ahead to increase performance.
To simplify read ahead management, the read ahead will not wrap over bcache end, so in worst case, single block physical read will be performed to fill the last block in bcache.

Booting from a virtual CD over IPMI:
0ms latency, before: 27 second, after: 7 seconds
60ms latency, before: over 12 minutes, after: under 5 minutes.

Submitted by: Toomas Soome <tsoome@me.com>
Reviewed by: delphij (previous version), emaste (previous version)
Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D4713

Spin the twiddle in dosfs to give visual feedback for disk I/O on
FAT filesystems as is done for other filesystems in the loader.

MFC after: 1 week

Fix readdir for the root directory on a FAT32 file system. The root
directory is like any subdirectory and as such needs to use a real
cluster number. To this end, keep a DE structure for the root in
the DOS_FS structure and populate it accordingly.

While here:
o allow consecutive path separators by skipping them all.
o add missing $FreeBSD$ keyword to dosfs.h.

Support long filenames.

Obtained from: Juniper Networks, Inc.

- Comment out unused variable.
- Add parentheses around expression to eliminate compiler warning.

Implement the fo_readdir method. This does not support long
file names.

Obtained from: Juniper Networks, Inc.
MFC after: 1 week

Don't add integers to void pointers.

Clean up error handling in libstand filesystem code to be more consistent:
- bzipfs and gzipfs now properly return errno values directly from their
read routines rather than returning -1.
- missing errno values on error returns for the seek routines on almost
all filesystems were added.
- fstat() now returns -1 if an error occurs rather than ignoring it.
- nfs's readdir() routine now reports valid errno values if an error or
EOF occurs rather than EPERM (It was just returning 0 for success and
1 for failure).
- nullfs used the wrong semantics for every function besides close() and
seek(). Getting it right for close() appears to be an accident at that.
- read() for buffered files no longer returns 0 (EOF) if an error occurs,
but returns -1 instead.

Add __FBSDID()s to libstand

Add a readdir function to the loader fsops vector, and implement the
functionality for some of the filesystesms.

More egcs warning fixes:
o use braces to avoid potentially ambiguous else
o don't default to type int (and also remove a useless register
modifier).
o Use parens around assignment values used as truth values.
o Remove unused function.

Reviewed by: obrien and chuckr

Enable the DOS filesystem. This allows reading from various DOS filesystems
(FAT12/16/32, VFAT).

Make a private copy of strcasecmp, as the "real" one uses the system ctype
header, which introduces locale poisoning.

Add support for reading directories as files.
Sort out fs_ops, alloc/free.

This commit was generated by cvs2svn to compensate for changes in r38451,
which included commits to RCS files with non-trunk default branches.

This is libstand; a support library for standalone executables (eg. bootstrap
modules).
Obtained from: NetBSD, with some architectural changes and many additions.