Enhance 'cgpt find' command to match keyblocks if desired.
This is part of the proposed developer-mode installation process, where we
want to detect that whoever is fiddling with the hard drive has already
fiddled with it before. Otherwise, we'll make them wait a bit to prevent
drive-by updates.
BUG=chromium-os:5306
Change-Id: Ifd6dce69180fa818fe14dbc3b1ac3485fb15d1c9
Review URL: http://codereview.chromium.org/3122023
diff --git a/cgpt/cmd_find.c b/cgpt/cmd_find.c
index b50400e..403d40f 100644
--- a/cgpt/cmd_find.c
+++ b/cgpt/cmd_find.c
@@ -28,6 +28,10 @@
" -v Be verbose in displaying matches (repeatable)\n"
" -n Numeric output only\n"
" -1 Fail if more than one match is found\n"
+ " -M FILE"
+ " Matching partition data must also contain FILE content\n"
+ " -O NUM"
+ " Byte offset into partition to match content (default 0)\n"
"\n", progname);
PrintTypes();
}
@@ -40,6 +44,10 @@
static int set_label = 0;
static int oneonly = 0;
static int numeric = 0;
+static uint8_t *matchbuf = NULL;
+static uint64_t matchlen = 0;
+static uint64_t matchoffset = 0;
+static uint8_t *comparebuf = NULL;
static Guid unique_guid;
static Guid type_guid;
@@ -47,6 +55,8 @@
static int hits = 0;
#define BUFSIZE 1024
+// FIXME: currently we only support 512-byte sectors.
+#define LBA_SIZE 512
// remember one of the possibly many hits
@@ -54,6 +64,86 @@
static char match_filename[BUFSIZE]; // matching filename
+// read a file into a buffer, return buffer and update size
+static uint8_t *ReadFile(const char *filename, uint64_t *size) {
+ FILE *f;
+ uint8_t *buf;
+
+ f = fopen(filename, "rb");
+ if (!f) {
+ return NULL;
+ }
+
+ fseek(f, 0, SEEK_END);
+ *size = ftell(f);
+ rewind(f);
+
+ buf = malloc(*size);
+ if (!buf) {
+ fclose(f);
+ return NULL;
+ }
+
+ if(1 != fread(buf, *size, 1, f)) {
+ fclose(f);
+ free(buf);
+ return NULL;
+ }
+
+ fclose(f);
+ return buf;
+}
+
+// fill comparebuf with the data to be examined, returning true on success.
+static int FillBuffer(int fd, uint64_t pos, uint64_t count) {
+ uint8_t *bufptr = comparebuf;
+
+ if (-1 == lseek(fd, pos, SEEK_SET))
+ return 0;
+
+ // keep reading until done or error
+ while (count) {
+ ssize_t bytes_read = read(fd, bufptr, count);
+ // negative means error, 0 means (unexpected) EOF
+ if (bytes_read <= 0)
+ return 0;
+ count -= bytes_read;
+ bufptr += bytes_read;
+ }
+
+ return 1;
+}
+
+// check partition data content. return true for match, 0 for no match or error
+static int match_content(struct drive *drive, GptEntry *entry) {
+ uint64_t part_size;
+
+ if (!matchlen)
+ return 1;
+
+ // Ensure that the region we want to match against is inside the partition.
+ part_size = LBA_SIZE * (entry->ending_lba - entry->starting_lba + 1);
+ if (matchoffset + matchlen > part_size) {
+ return 0;
+ }
+
+ // Read the partition data.
+ if (!FillBuffer(drive->fd,
+ (LBA_SIZE * entry->starting_lba) + matchoffset,
+ matchlen)) {
+ Error("unable to read partition data\n");
+ return 0;
+ }
+
+ // Compare it
+ if (0 == memcmp(matchbuf, comparebuf, matchlen)) {
+ return 1;
+ }
+
+ // Nope.
+ return 0;
+}
+
// FIXME: This needs to handle /dev/mmcblk0 -> /dev/mmcblk0p3
static void showmatch(char *filename, int partnum, GptEntry *entry) {
printf("%s%d\n", filename, partnum);
@@ -96,7 +186,7 @@
found = 1;
}
}
- if (found) {
+ if (found && match_content(&drive, entry)) {
hits++;
retval++;
showmatch(filename, i+1, entry);
@@ -111,7 +201,7 @@
return retval;
}
-
+
#define PROC_PARTITIONS "/proc/partitions"
#define DEV_DIR "/dev"
@@ -128,12 +218,9 @@
static char pathname[BUFSIZE]; // we'll return this.
char tmpname[BUFSIZE];
-// printf("basename is %s\n", basename);
-
- // It should be a block device under /dev/,
+ // It should be a block device under /dev/,
for (i = 0; devdirs[i]; i++) {
sprintf(pathname, "%s/%s", devdirs[i], basename);
-// printf(" look at %s\n", pathname);
if (0 != stat(pathname, &statbuf))
continue;
@@ -143,7 +230,6 @@
// It should have a symlink called /sys/block/*/device
sprintf(tmpname, "%s/%s/device", SYS_BLOCK_DIR, basename);
-// printf(" look at %s\n", tmpname);
if (0 != lstat(tmpname, &statbuf))
continue;
@@ -177,7 +263,7 @@
while (fgets(line, sizeof(line), fp)) {
int ma, mi;
long long unsigned int sz;
-
+
if (sscanf(line, " %d %d %llu %128[^\n ]", &ma, &mi, &sz, partname) != 4)
continue;
@@ -187,20 +273,20 @@
}
}
}
-
+
fclose(fp);
return found;
}
-
+
int cmd_find(int argc, char *argv[]) {
int i;
-
int errorcnt = 0;
+ char *e = 0;
int c;
-
+
opterr = 0; // quiet, you
- while ((c=getopt(argc, argv, ":hv1nt:u:l:")) != -1)
+ while ((c=getopt(argc, argv, ":hv1nt:u:l:M:O:")) != -1)
{
switch (c)
{
@@ -232,6 +318,27 @@
errorcnt++;
}
break;
+ case 'M':
+ matchbuf = ReadFile(optarg, &matchlen);
+ if (!matchbuf || !matchlen) {
+ Error("Unable to read from %s\n", optarg);
+ errorcnt++;
+ }
+ // Go ahead and allocate space for the comparison too
+ comparebuf = (uint8_t *)malloc(matchlen);
+ if (!comparebuf) {
+ Error("Unable to allocate %" PRIu64 "bytes for comparison buffer\n",
+ matchlen);
+ errorcnt++;
+ }
+ break;
+ case 'O':
+ matchoffset = strtoull(optarg, &e, 0);
+ if (!*optarg || (e && *e)) {
+ Error("invalid argument to -%c: \"%s\"\n", c, optarg);
+ errorcnt++;
+ }
+ break;
case 'h':
Usage();
@@ -249,13 +356,16 @@
break;
}
}
+ if (!set_unique && !set_type && !set_label) {
+ Error("You must specify at least one of -t, -u, or -l\n");
+ errorcnt++;
+ }
if (errorcnt)
{
Usage();
return CGPT_FAILED;
}
-
if (optind < argc) {
for (i=optind; i<argc; i++)
do_search(argv[i]);