grubby/0002-Add-btrfs-subvolume-support-for-grub2.patch

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2018-03-05 18:52:23 +00:00
From 5dec033b19bb5b07a0a136a7357e16c8ca9f5dd6 Mon Sep 17 00:00:00 2001
From: Nathaniel McCallum <npmccallum@redhat.com>
Date: Fri, 2 Mar 2018 08:40:18 -0500
Subject: [PATCH 2/3] Add btrfs subvolume support for grub2
In order to find the subvolume prefix from a given path, we parse
/proc/mounts. In cases where /proc/mounts doesn't contain the
filesystem, the caller can use the --mounts option to specify his own
mounts file.
Btrfs subvolumes are already supported by grub2 and by grub2-mkconfig.
Fixes #22
---
grubby.c | 148 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++---
1 file changed, 143 insertions(+), 5 deletions(-)
diff --git a/grubby.c b/grubby.c
index a062ef8..96d252a 100644
--- a/grubby.c
+++ b/grubby.c
@@ -68,6 +68,8 @@ int isEfi = 0;
char *saved_command_line = NULL;
+const char *mounts = "/proc/mounts";
+
/* comments get lumped in with indention */
struct lineElement {
char * item;
@@ -1834,6 +1836,129 @@ static int endswith(const char *s, char c)
return s[slen] == c;
}
+typedef struct {
+ const char *start;
+ size_t chars;
+} field;
+
+static int iscomma(int c)
+{
+ return c == ',';
+}
+
+static int isequal(int c)
+{
+ return c == '=';
+}
+
+static field findField(const field *in, typeof(isspace) *isdelim, field *out)
+{
+ field nxt = {};
+ size_t off = 0;
+
+ while (off < in->chars && isdelim(in->start[off]))
+ off++;
+
+ if (off == in->chars)
+ return nxt;
+
+ out->start = &in->start[off];
+ out->chars = 0;
+
+ while (off + out->chars < in->chars && !isdelim(out->start[out->chars]))
+ out->chars++;
+
+ nxt.start = out->start + out->chars;
+ nxt.chars = in->chars - off - out->chars;
+ return nxt;
+}
+
+static int fieldEquals(const field *in, const char *str)
+{
+ return in->chars == strlen(str) &&
+ strncmp(in->start, str, in->chars) == 0;
+}
+
+/* Parse /proc/mounts to determine the subvolume prefix. */
+static size_t subvolPrefix(const char *str)
+{
+ FILE *file = NULL;
+ char *line = NULL;
+ size_t prfx = 0;
+ size_t size = 0;
+
+ file = fopen(mounts, "r");
+ if (!file)
+ return 0;
+
+ for (ssize_t s; (s = getline(&line, &size, file)) >= 0; ) {
+ field nxt = { line, s };
+ field dev = {};
+ field path = {};
+ field type = {};
+ field opts = {};
+ field opt = {};
+
+ nxt = findField(&nxt, isspace, &dev);
+ if (!nxt.start)
+ continue;
+
+ nxt = findField(&nxt, isspace, &path);
+ if (!nxt.start)
+ continue;
+
+ nxt = findField(&nxt, isspace, &type);
+ if (!nxt.start)
+ continue;
+
+ nxt = findField(&nxt, isspace, &opts);
+ if (!nxt.start)
+ continue;
+
+ if (!fieldEquals(&type, "btrfs"))
+ continue;
+
+ /* We have found a btrfs mount point. */
+
+ nxt = opts;
+ while ((nxt = findField(&nxt, iscomma, &opt)).start) {
+ field key = {};
+ field val = {};
+
+ opt = findField(&opt, isequal, &key);
+ if (!opt.start)
+ continue;
+
+ opt = findField(&opt, isequal, &val);
+ if (!opt.start)
+ continue;
+
+ if (!fieldEquals(&key, "subvol"))
+ continue;
+
+ /* We have found a btrfs subvolume mount point. */
+
+ if (strncmp(val.start, str, val.chars))
+ continue;
+
+ if (val.start[val.chars - 1] != '/' &&
+ str[val.chars] != '/')
+ continue;
+
+ /* The subvolume mount point matches our input. */
+
+ if (prfx < val.chars)
+ prfx = val.chars;
+ }
+ }
+
+ dbgPrintf("%s(): str: '%s', prfx: '%s'\n", __FUNCTION__, str, prfx);
+
+ fclose(file);
+ free(line);
+ return prfx;
+}
+
int suitableImage(struct singleEntry * entry, const char * bootPrefix,
int skipRemoved, int flags) {
struct singleLine * line;
@@ -2794,12 +2919,22 @@ struct singleLine * addLineTmpl(struct singleEntry * entry,
/* but try to keep the rootspec from the template... sigh */
if (tmplLine->type & (LT_HYPER|LT_KERNEL|LT_MBMODULE|LT_INITRD|LT_KERNEL_EFI|LT_INITRD_EFI|LT_KERNEL_16|LT_INITRD_16)) {
- size_t rs = getRootSpecifier(tmplLine->elements[1].item);
+ const char *prfx = tmplLine->elements[1].item;
+ size_t rs = getRootSpecifier(prfx);
+ if (isinitrd(tmplLine->type)) {
+ for (struct singleLine *l = entry->lines;
+ rs == 0 && l; l = l->next) {
+ if (iskernel(l->type)) {
+ prfx = l->elements[1].item;
+ rs = getRootSpecifier(prfx);
+ }
+ }
+ }
if (rs > 0) {
free(newLine->elements[1].item);
- newLine->elements[1].item = sdupprintf("%.*s%s", (int) rs,
- tmplLine->elements[1].item, val);
- }
+ newLine->elements[1].item = sdupprintf("%.*s%s",
+ (int) rs, prfx, val);
+ }
}
}
@@ -3738,7 +3873,7 @@ static size_t getRootSpecifier(const char *str)
rs++;
}
- return rs;
+ return rs + subvolPrefix(str + rs);
}
static char * getInitrdVal(struct grubConfig * config,
@@ -4253,6 +4388,9 @@ int main(int argc, const char ** argv) {
{ "mbargs", 0, POPT_ARG_STRING, &newMBKernelArgs, 0,
_("default arguments for the new multiboot kernel or "
"new arguments for multiboot kernel being updated"), NULL },
+ { "mounts", 0, POPT_ARG_STRING, &mounts, 0,
+ _("path to fake /proc/mounts file (for testing only)"),
+ _("mounts") },
{ "bad-image-okay", 0, 0, &badImageOkay, 0,
_("don't sanity check images in boot entries (for testing only)"),
NULL },
--
2.14.3