blkid: add ID_FS_AMBIVALENT for udev output

UI tools that read information from udev need a way how inform users
about ambivalent probing result (more valid filesystems on the
device).

This patch add a new ID_FS_AMBIVALENT variable:

	ID_FS_AMBIVALENT=<info> <info> [ ...]

where <info> is:

	<usage>:<type>[:<version>]

all strings are encoded (white spaces and utf8 are replaced with \hex).

For example:

	# blkid -p -o udev /dev/sda1
	ID_FS_AMBIVALEN=filesystem:vfat:FAT12 other:swap:2

Signed-off-by: Karel Zak <kzak@redhat.com>

diff --git a/misc-utils/blkid.c b/misc-utils/blkid.c
index 0182a9bb26e92915dc924c3880de2e26520be06d..6e055a9533fd07c3c29ddf73f3a1c8d1087328f7 100644 (file)
--- a/misc-utils/blkid.c
+++ b/misc-utils/blkid.c
@@ -323,6 +323,84 @@ static void print_tags(blkid_dev dev, char *show[], int output)
                printf("\n");
 }
 
+
+static int append_str(char **res, size_t *sz, const char *a, const char *b)
+{
+       char *str = *res;
+       size_t asz = a ? strlen(a) : 0;
+       size_t bsz = b ? strlen(b) : 0;
+       size_t len = *sz + asz + bsz;
+
+       if (!len)
+               return -1;
+
+       str = realloc(str, len + 1);
+       if (!str) {
+               free(*res);
+               return -1;
+       }
+       *res = str;
+       str += *sz;
+
+       if (a) {
+               memcpy(str, a, asz);
+               str += asz;
+       }
+       if (b) {
+               memcpy(str, b, bsz);
+               str += bsz;
+       }
+       *str = '\0';
+       *sz = len;
+       return 0;
+}
+
+/*
+ * Compose and print ID_FS_AMBIVALENT for udev
+ */
+static int print_udev_ambivalent(blkid_probe pr)
+{
+       char *val = NULL;
+       size_t valsz = 0;
+       int count = 0, rc = -1;
+
+       while (!blkid_do_probe(pr)) {
+               const char *usage = NULL, *type = NULL, *version = NULL;
+               char enc[256];
+
+               blkid_probe_lookup_value(pr, "USAGE", &usage, NULL);
+               blkid_probe_lookup_value(pr, "TYPE", &type, NULL);
+               blkid_probe_lookup_value(pr, "VERSION", &version, NULL);
+
+               if (!usage || !type)
+                       continue;
+
+               blkid_encode_string(usage, enc, sizeof(enc));
+               if (append_str(&val, &valsz, enc, ":"))
+                       goto done;
+
+               blkid_encode_string(type, enc, sizeof(enc));
+               if (append_str(&val, &valsz, enc, version ? ":" : " "))
+                       goto done;
+
+               if (version) {
+                       blkid_encode_string(version, enc, sizeof(enc));
+                       if (append_str(&val, &valsz, enc, " "))
+                               goto done;
+               }
+               count++;
+       }
+
+       if (count > 1) {
+               *(val + valsz - 1) = '\0';              /* rem tailing whitespace */
+               printf("ID_FS_AMBIVALEN=%s\n", val);
+               rc = 0;
+       }
+done:
+       free(val);
+       return rc;
+}
+
 static int lowprobe_device(blkid_probe pr, const char *devname,        char *show[],
                        int output, blkid_loff_t offset, blkid_loff_t size)
 {
@@ -362,10 +440,16 @@ static int lowprobe_device(blkid_probe pr, const char *devname,   char *show[],
        if (nvals > 1 && !(output & (OUTPUT_VALUE_ONLY | OUTPUT_UDEV_LIST)))
                printf("\n");
 done:
-       if (rc == -2)
-               fprintf(stderr, "%s: ambivalent result "
-                               "(probably more filesystems on the device)\n",
+       if (rc == -2) {
+               if (output & OUTPUT_UDEV_LIST)
+                       print_udev_ambivalent(pr);
+               else
+                       fprintf(stderr,
+                               "%s: ambivalent result (probably more "
+                               "filesystems on the device, use wipefs(8) "
+                               "to see more details)\n",
                                devname);
+       }
        close(fd);
        return !nvals ? 2 : 0;
 }