cmd/snap-update-ns: add compare function for mount entries #2848
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This patch adds a simple function for comparing mount entries. This will be followed up with a simple routine that sorts two lists of mount entries qucikly. Signed-off-by: Zygmunt Krynicki <zygmunt.krynicki@canonical.com>
| @@ -31,6 +31,16 @@ | |||
| #include "../libsnap-confine-private/cleanup-funcs.h" | |||
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| /** | |||
| * Compare two mount entries (through indirect pointers). | |||
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maybe add a "(needed for using from qsort)" to the comment so people don't scratch their heads as I did
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This one is static and it will show up in the next branch.
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Agreed, without further context the need for this is awkward indeed.
| { | ||
| int result; | ||
| if (a == NULL || b == NULL) { | ||
| die("cannot compare NULL mount entry"); |
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not even if they're both NULL :-p?
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No, we never have NULL entries that mean anything. We only have an empty list that is expressed by an NULL entry. The sorting routine will not compare NULL pointers.
| if (a == NULL || b == NULL) { | ||
| die("cannot compare NULL mount entry"); | ||
| } | ||
| result = strcmp(a->entry.mnt_fsname, b->entry.mnt_fsname); |
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how sure are we that all these fields are non-null?
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100% sure, we copy those with an explicit check that converts NULL to ""
| * | ||
| * Returns 0 if both entries are equal, a number less than zero if the first | ||
| * entry sorts before the second entry or a number greater than zero if the | ||
| * second entry sorts before the second entry. |
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End of the sentence has two "second entry".
| @@ -31,6 +31,16 @@ | |||
| #include "../libsnap-confine-private/cleanup-funcs.h" | |||
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| /** | |||
| * Compare two mount entries (through indirect pointers). | |||
There was a problem hiding this comment.
Agreed, without further context the need for this is awkward indeed.
This patch adds a simple function for comparing mount entries. This will
be followed up with a simple routine that sorts two lists of mount
entries quickly.
Signed-off-by: Zygmunt Krynicki zygmunt.krynicki@canonical.com