* commit '1642edb5208fe02ef64d5734fffaf7c4a724fd2f':
bionic: store property names as variable-length strings
bionic: prevent root processes from calling __system_property_add
bionic: revert to a single (larger) property area
bionic: reimplement property area as hybrid trie/binary tree
bionic: add missing memory barriers to system properties
bionic: make property area expandable
* changes:
bionic: store property names as variable-length strings
bionic: prevent root processes from calling __system_property_add
bionic: revert to a single (larger) property area
bionic: reimplement property area as hybrid trie/binary tree
bionic: add missing memory barriers to system properties
bionic: make property area expandable
Names are immutable, so the fixed-sized arrays can be replaced with
variable-length ones to save memory (especially on internal tree nodes).
Signed-off-by: Greg Hackmann <ghackmann@google.com>
(cherry picked from commit 492ce95d9f)
Change-Id: Ib074192d1b71150233d78c58e9ffcf7ecf688b6b
If a root process other than init calls __system_property_add, which
it should never do, it will break the design assumption that there is
only one mutator.
Pass O_EXCL to open() in map_prop_region_rw to ensure that only one
process ever has the property pages open for write.
(cherry picked from commit fb9b7b436f)
Change-Id: I6df3afedbfb5d07891b095aa24b78278381a5aaf
d329697 is too complicated. Change the multiple property pages back to
a single 128K property area that's mapped in entirely at initialization
(the memory will not get allocated until the pages are touched).
d329697 has other changes useful for testing (moving property area
initialization inside bionic and adding __system_property_set_filename)
so undo the change manually rather than with git revert.
Signed-off-by: Greg Hackmann <ghackmann@google.com>
(cherry picked from commit 5f05348c18)
Change-Id: I690704552afc07a4dd410277893ca9c40bc13e5f
See the comments for an explanation of how properties are stored.
The trie structure is designed to scale better than the previous
array-based implementation. Searching an array with n properties
required average O(n) string compares of the entire key; searching the
trie requires average O(log n) string compares of each token (substrings
between '.' characters).
Signed-off-by: Greg Hackmann <ghackmann@google.com>
(cherry picked from commit 6ac8e6a46d)
Change-Id: Icbe31908572f33b4d9b85d5b62ac837cbd0f85e0
1) Reading the value must finish before checking whether it's intact
2) Setting the serial's dirty bit must visible before modifying the
value
3) The modified value must be visible before clearing the serial's dirty
bit
4) New properties and their TOC entries must be visible before updating
the property count
Signed-off-by: Greg Hackmann <ghackmann@google.com>
(cherry picked from commit 5bfa3ee8b3)
Change-Id: Id3fa45261fc2df2ae493ab5194bc2b6bff04e966
The property area is initially one 4K region, automatically expanding as
needed up to 64 regions.
To avoid duplicating code, __system_property_area_init() now allocates
and initializes the first region (previously it was allocated in init's
init_property_area() and initialized in bionic). For testing purposes,
__system_property_set_filename() may be used to override the file used
to map in regions.
Signed-off-by: Greg Hackmann <ghackmann@google.com>
(cherry picked from commit d32969701b)
Change-Id: I038d451fe8849b0c4863663eec6f57f6521bf4a7
Text relocations unnecessarily mark pages as dirty, preventing them
from being swapped out, wasting memory. Also, text relocations
prevent the code from running on certain hardened systems.
Print a message in logcat and stderr when we see a text relocation,
to encourage developers to fix their code.
Change-Id: I6051a7463911e090ae5727a355397d539669d5b9
Avoid keeping unnecessary file descriptors around when they're not
needed. Libc doesn't log so much that opening / closing overhead
matters.
Change-Id: I590ec5c27562db9bac025f781c48ec9a7724ce77
find_nth() will be inefficient on a trie. Since find_nth() is only used
internally and only for enumerating properties, we can add a foreach()
function to do this directly.
Signed-off-by: Greg Hackmann <ghackmann@google.com>
(cherry picked from commit 577418403d)
Change-Id: Iaca97d1182ce2c28863ba85241cbb5cf6185eb2f
This matches glibc and makes life easier for developers who want to
sometimes preload a library from init (which has no conditionals); they
can simply move/remove the library to disable.
Change-Id: I579b8633f958235af6e46bb53b378b9e363afb1f
The properties benchmarks were reading n properties from a property
area with n properties in it, which was making it hard to compare
the time between runs of different sizes. Change the benchmark
to read a random property per iteration so the numbers between
runs are comparable.
Change-Id: Ib1648ce0948d9038fce76d209608427376cfb8da
