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[src/trunk]: src/usr.sbin/fstyp fstyp: Show exFAT volume labels with -l flag



details:   https://anonhg.NetBSD.org/src/rev/cca91789e9ae
branches:  trunk
changeset: 967936:cca91789e9ae
user:      tkusumi <tkusumi%NetBSD.org@localhost>
date:      Sat Dec 28 08:00:08 2019 +0000

description:
fstyp: Show exFAT volume labels with -l flag

taken-from: FreeBSD (freebsd/freebsd@73773fcda9f69ce7ee0c73292f273bab940223bf)

diffstat:

 usr.sbin/fstyp/exfat.c |  302 ++++++++++++++++++++++++++++++++++++++++++++++++-
 usr.sbin/fstyp/fstyp.c |   50 ++++++--
 usr.sbin/fstyp/fstyp.h |    9 +-
 3 files changed, 343 insertions(+), 18 deletions(-)

diffs (truncated from 467 to 300 lines):

diff -r 343f0c15a0aa -r cca91789e9ae usr.sbin/fstyp/exfat.c
--- a/usr.sbin/fstyp/exfat.c    Sat Dec 28 04:23:26 2019 +0000
+++ b/usr.sbin/fstyp/exfat.c    Sat Dec 28 08:00:08 2019 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: exfat.c,v 1.1 2019/11/18 14:53:34 tkusumi Exp $        */
+/*     $NetBSD: exfat.c,v 1.2 2019/12/28 08:00:08 tkusumi Exp $        */
 
 /*
  * Copyright (c) 2017 Conrad Meyer <cem%FreeBSD.org@localhost>
@@ -26,8 +26,16 @@
  * SUCH DAMAGE.
  */
 #include <sys/cdefs.h>
-__RCSID("$NetBSD: exfat.c,v 1.1 2019/11/18 14:53:34 tkusumi Exp $");
+__RCSID("$NetBSD: exfat.c,v 1.2 2019/12/28 08:00:08 tkusumi Exp $");
+
+#include <sys/param.h>
+#include <sys/endian.h>
 
+#include <assert.h>
+#include <err.h>
+#include <errno.h>
+#include <iconv.h>
+#include <stdbool.h>
 #include <stdint.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -35,6 +43,10 @@
 
 #include "fstyp.h"
 
+/*
+ * https://docs.microsoft.com/en-us/windows/win32/fileio/exfat-specification
+ */
+
 struct exfat_vbr {
        char            ev_jmp[3];
        char            ev_fsname[8];
@@ -56,19 +68,301 @@
        uint8_t         ev_percent_used;
 } __packed;
 
+struct exfat_dirent {
+       uint8_t         xde_type;
+#define        XDE_TYPE_INUSE_MASK     0x80    /* 1=in use */
+#define        XDE_TYPE_INUSE_SHIFT    7
+#define        XDE_TYPE_CATEGORY_MASK  0x40    /* 0=primary */
+#define        XDE_TYPE_CATEGORY_SHIFT 6
+#define        XDE_TYPE_IMPORTNC_MASK  0x20    /* 0=critical */
+#define        XDE_TYPE_IMPORTNC_SHIFT 5
+#define        XDE_TYPE_CODE_MASK      0x1f
+/* InUse=0, ..., TypeCode=0: EOD. */
+#define        XDE_TYPE_EOD            0x00
+#define        XDE_TYPE_ALLOC_BITMAP   (XDE_TYPE_INUSE_MASK | 0x01)
+#define        XDE_TYPE_UPCASE_TABLE   (XDE_TYPE_INUSE_MASK | 0x02)
+#define        XDE_TYPE_VOL_LABEL      (XDE_TYPE_INUSE_MASK | 0x03)
+#define        XDE_TYPE_FILE           (XDE_TYPE_INUSE_MASK | 0x05)
+#define        XDE_TYPE_VOL_GUID       (XDE_TYPE_INUSE_MASK | XDE_TYPE_IMPORTNC_MASK)
+#define        XDE_TYPE_STREAM_EXT     (XDE_TYPE_INUSE_MASK | XDE_TYPE_CATEGORY_MASK)
+#define        XDE_TYPE_FILE_NAME      (XDE_TYPE_INUSE_MASK | XDE_TYPE_CATEGORY_MASK | 0x01)
+#define        XDE_TYPE_VENDOR         (XDE_TYPE_INUSE_MASK | XDE_TYPE_CATEGORY_MASK | XDE_TYPE_IMPORTNC_MASK)
+#define        XDE_TYPE_VENDOR_ALLOC   (XDE_TYPE_INUSE_MASK | XDE_TYPE_CATEGORY_MASK | XDE_TYPE_IMPORTNC_MASK | 0x01)
+       union {
+               uint8_t xde_generic_[19];
+               struct exde_primary {
+                       /*
+                        * Count of "secondary" dirents following this one.
+                        *
+                        * A single logical entity may be composed of a
+                        * sequence of several dirents, starting with a primary
+                        * one; the rest are secondary dirents.
+                        */
+                       uint8_t         xde_secondary_count_;
+                       uint16_t        xde_set_chksum_;
+                       uint16_t        xde_prim_flags_;
+                       uint8_t         xde_prim_generic_[14];
+               } __packed xde_primary_;
+               struct exde_secondary {
+                       uint8_t         xde_sec_flags_;
+                       uint8_t         xde_sec_generic_[18];
+               } __packed xde_secondary_;
+       } u;
+       uint32_t        xde_first_cluster;
+       uint64_t        xde_data_len;
+} __packed;
+#define        xde_generic             u.xde_generic_
+#define        xde_secondary_count     u.xde_primary_.xde_secondary_count
+#define        xde_set_chksum          u.xde_primary_.xde_set_chksum_
+#define        xde_prim_flags          u.xde_primary_.xde_prim_flags_
+#define        xde_sec_flags           u.xde_secondary_.xde_sec_flags_
+_Static_assert(sizeof(struct exfat_dirent) == 32, "spec");
+
+struct exfat_de_label {
+       uint8_t         xdel_type;      /* XDE_TYPE_VOL_LABEL */
+       uint8_t         xdel_char_cnt;  /* Length of UCS-2 label */
+       uint16_t        xdel_vol_lbl[11];
+       uint8_t         xdel_reserved[8];
+} __packed;
+_Static_assert(sizeof(struct exfat_de_label) == 32, "spec");
+
+#define        MAIN_BOOT_REGION_SECT   0
+#define        BACKUP_BOOT_REGION_SECT 12
+
+#define        SUBREGION_CHKSUM_SECT   11
+
+#define        FIRST_CLUSTER           2
+#define        BAD_BLOCK_SENTINEL      0xfffffff7u
+#define        END_CLUSTER_SENTINEL    0xffffffffu
+
+static inline void *
+read_sectn(FILE *fp, off_t sect, unsigned count, unsigned bytespersec)
+{
+       return (read_buf(fp, sect * bytespersec, bytespersec * count));
+}
+
+static inline void *
+read_sect(FILE *fp, off_t sect, unsigned bytespersec)
+{
+       return (read_sectn(fp, sect, 1, bytespersec));
+}
+
+/*
+ * Compute the byte-by-byte multi-sector checksum of the given boot region
+ * (MAIN or BACKUP), for a given bytespersec (typically 512 or 4096).
+ *
+ * Endian-safe; result is host endian.
+ */
+static int
+exfat_compute_boot_chksum(FILE *fp, unsigned region, unsigned bytespersec,
+    uint32_t *result)
+{
+       unsigned char *sector;
+       unsigned n, sect;
+       uint32_t checksum;
+
+       checksum = 0;
+       for (sect = 0; sect < 11; sect++) {
+               sector = read_sect(fp, region + sect, bytespersec);
+               if (sector == NULL)
+                       return (ENXIO);
+               for (n = 0; n < bytespersec; n++) {
+                       if (sect == 0) {
+                               switch (n) {
+                               case 106:
+                               case 107:
+                               case 112:
+                                       continue;
+                               }
+                       }
+                       checksum = ((checksum & 1) ? 0x80000000u : 0u) +
+                           (checksum >> 1) + (uint32_t)sector[n];
+               }
+               free(sector);
+       }
+
+       *result = checksum;
+       return (0);
+}
+
+static void
+convert_label(const uint16_t *ucs2label /* LE */, unsigned ucs2len, char
+    *label_out, size_t label_sz)
+{
+       const char *label;
+       char *label_out_orig;
+       iconv_t cd;
+       size_t srcleft, rc;
+
+       /* Currently hardcoded in fstyp.c as 256 or so. */
+       assert(label_sz > 1);
+
+       if (ucs2len == 0) {
+               /*
+                * Kind of seems bogus, but the spec allows an empty label
+                * entry with the same meaning as no label.
+                */
+               return;
+       }
+
+       if (ucs2len > 11) {
+               warnx("exfat: Bogus volume label length: %u", ucs2len);
+               return;
+       }
+
+       /* dstname="" means convert to the current locale. */
+       cd = iconv_open("", EXFAT_ENC);
+       if (cd == (iconv_t)-1) {
+               warn("exfat: Could not open iconv");
+               return;
+       }
+
+       label_out_orig = label_out;
+
+       /* Dummy up the byte pointer and byte length iconv's API wants. */
+       label = (const void *)ucs2label;
+       srcleft = ucs2len * sizeof(*ucs2label);
+
+       rc = iconv(cd, __UNCONST(&label), &srcleft, &label_out,
+           &label_sz);
+       if (rc == (size_t)-1) {
+               warn("exfat: iconv()");
+               *label_out_orig = '\0';
+       } else {
+               /* NUL-terminate result (iconv advances label_out). */
+               if (label_sz == 0)
+                       label_out--;
+               *label_out = '\0';
+       }
+
+       iconv_close(cd);
+}
+
+/*
+ * Using the FAT table, look up the next cluster in this chain.
+ */
+static uint32_t
+exfat_fat_next(FILE *fp, const struct exfat_vbr *ev, unsigned BPS,
+    uint32_t cluster)
+{
+       uint32_t fat_offset_sect, clsect, clsectoff;
+       uint32_t *fatsect, nextclust;
+
+       fat_offset_sect = le32toh(ev->ev_fat_offset);
+       clsect = fat_offset_sect + (cluster / (BPS / (uint32_t)sizeof(cluster)));
+       clsectoff = (cluster % (BPS / sizeof(cluster)));
+
+       /* XXX This is pretty wasteful without a block cache for the FAT. */
+       fatsect = read_sect(fp, clsect, BPS);
+       nextclust = le32toh(fatsect[clsectoff]);
+       free(fatsect);
+
+       return (nextclust);
+}
+
+static void
+exfat_find_label(FILE *fp, const struct exfat_vbr *ev, unsigned BPS,
+    char *label_out, size_t label_sz)
+{
+       uint32_t rootdir_cluster, sects_per_clust, cluster_offset_sect;
+       off_t rootdir_sect;
+       struct exfat_dirent *declust, *it;
+
+       cluster_offset_sect = le32toh(ev->ev_cluster_offset);
+       rootdir_cluster = le32toh(ev->ev_rootdir_cluster);
+       sects_per_clust = (1u << ev->ev_log_sect_per_clust);
+
+       if (rootdir_cluster < FIRST_CLUSTER) {
+               warnx("%s: invalid rootdir cluster %u < %d", __func__,
+                   rootdir_cluster, FIRST_CLUSTER);
+               return;
+       }
+
+
+       for (; rootdir_cluster != END_CLUSTER_SENTINEL;
+           rootdir_cluster = exfat_fat_next(fp, ev, BPS, rootdir_cluster)) {
+               if (rootdir_cluster == BAD_BLOCK_SENTINEL) {
+                       warnx("%s: Bogus bad block in root directory chain",
+                           __func__);
+                       return;
+               }
+
+               rootdir_sect = (rootdir_cluster - FIRST_CLUSTER) *
+                   sects_per_clust + cluster_offset_sect;
+               declust = read_sectn(fp, rootdir_sect, sects_per_clust, BPS);
+               for (it = declust;
+                   it < declust + (sects_per_clust * BPS / sizeof(*it)); it++) {
+                       bool eod = false;
+
+                       /*
+                        * Simplistic directory traversal; doesn't do any
+                        * validation of "MUST" requirements in spec.
+                        */
+                       switch (it->xde_type) {
+                       case XDE_TYPE_EOD:
+                               eod = true;
+                               break;
+                       case XDE_TYPE_VOL_LABEL: {
+                               struct exfat_de_label *lde = (void*)it;
+                               convert_label(lde->xdel_vol_lbl,
+                                   lde->xdel_char_cnt, label_out, label_sz);
+                               free(declust);
+                               return;
+                               }
+                       }
+
+                       if (eod)
+                               break;
+               }
+               free(declust);
+       }
+}
+
 int
 fstyp_exfat(FILE *fp, char *label, size_t size)
 {
        struct exfat_vbr *ev;
+       uint32_t *cksect;
+       unsigned bytespersec;
+       uint32_t chksum;
+       int error;



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