On Thu, Jul 16, 2015 at 01:10:20PM +0200, Thierry Reding wrote:
> From: Thierry Reding <treding@xxxxxxxxxx>
>
> Given a device tree node and a property name, the new fdt_find_string()
> function will look up a given string in the string list contained in the
> property's value and return its index.
>
> Signed-off-by: Thierry Reding <treding@xxxxxxxxxx>
This also looks good, except for the name. I'd prefer
'fdt_stringlist_search()' again to match the existing
'fdt_stringlist_contains()'.
Speaking of which, fdt_stringlist_contains() could be reimplemented in
terms of this function.
> ---
> Changes in v2:
> - handle non-NUL-terminated properties more gracefully
> - improve documentation
>
> libfdt/fdt_ro.c | 30 ++++++++++++++++++++++++++++++
> libfdt/libfdt.h | 22 ++++++++++++++++++++++
> tests/strings.c | 40 ++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 92 insertions(+)
>
> diff --git a/libfdt/fdt_ro.c b/libfdt/fdt_ro.c
> index cf55c71df79c..39b84b1cea60 100644
> --- a/libfdt/fdt_ro.c
> +++ b/libfdt/fdt_ro.c
> @@ -563,6 +563,36 @@ int fdt_count_strings(const void *fdt, int nodeoffset, const char *property)
> return count;
> }
>
> +int fdt_find_string(const void *fdt, int nodeoffset, const char *property,
> + const char *string)
> +{
> + int length, len, index = 0;
> + const char *list, *end;
> +
> + list = fdt_getprop(fdt, nodeoffset, property, &length);
> + if (!list)
> + return -length;
> +
> + len = strlen(string) + 1;
> + end = list + length;
> +
> + while (list < end) {
> + length = strnlen(list, end - list) + 1;
> +
> + /* Abort if the last string isn't properly NUL-terminated. */
> + if (list + length > end)
> + return -FDT_ERR_BADVALUE;
> +
> + if (length == len && memcmp(list, string, length) == 0)
> + return index;
> +
> + list += length;
> + index++;
> + }
> +
> + return -FDT_ERR_NOTFOUND;
> +}
> +
> int fdt_node_check_compatible(const void *fdt, int nodeoffset,
> const char *compatible)
> {
> diff --git a/libfdt/libfdt.h b/libfdt/libfdt.h
> index bf60c1593e4e..e64680dd741c 100644
> --- a/libfdt/libfdt.h
> +++ b/libfdt/libfdt.h
> @@ -885,6 +885,28 @@ int fdt_stringlist_contains(const char *strlist, int listlen, const char *str);
> */
> int fdt_count_strings(const void *fdt, int nodeoffset, const char *property);
>
> +/**
> + * fdt_find_string - find a string in a string list and return its index
> + * @fdt: pointer to the device tree blob
> + * @nodeoffset: offset of a tree node
> + * @property: name of the property containing the string list
> + * @string: string to look up in the string list
> + *
> + * Note that it is possible for this function to succeed on property values
> + * that are not NUL-terminated. That's because the function will stop after
> + * finding the first occurrence of @string. This can for example happen with
> + * small-valued cell properties, such as #address-cells, when searching for
> + * the empty string.
> + *
> + * @return:
> + * the index of the string in the list of strings
> + * -FDT_ERR_BADVALUE if the property value is not NUL-terminated
> + * -FDT_ERR_NOTFOUND if the property does not exist or does not contain
> + * the given string
> + */
> +int fdt_find_string(const void *fdt, int nodeoffset, const char *property,
> + const char *string);
> +
> /**********************************************************************/
> /* Read-only functions (addressing related) */
> /**********************************************************************/
> diff --git a/tests/strings.c b/tests/strings.c
> index e10d9ece5a3e..29c49bfcc78c 100644
> --- a/tests/strings.c
> +++ b/tests/strings.c
> @@ -40,6 +40,24 @@ static void check_expected_failure(const void *fdt, const char *path,
> err = fdt_count_strings(fdt, offset, "#address-cells");
> if (err != -FDT_ERR_BADVALUE)
> FAIL("unexpectedly succeeded in parsing #address-cells\n");
> +
> + err = fdt_find_string(fdt, offset, "#address-cells", "foo");
> + if (err != -FDT_ERR_BADVALUE)
> + FAIL("found string in #address-cells: %d\n", err);
> +
> + /*
> + * Note that the #address-cells property contains a small 32-bit
> + * unsigned integer, hence some bytes will be zero, and searching for
> + * the empty string will succeed.
> + *
> + * The reason for this oddity is that the function will exit when the
> + * first occurrence of the string is found, but in order to determine
> + * that the property does not contain a valid string list it would
> + * need to process the whole value.
> + */
> + err = fdt_find_string(fdt, offset, "#address-cells", "");
> + if (err != 0)
> + FAIL("empty string not found in #address-cells: %d\n", err);
> }
>
> static void check_string_count(const void *fdt, const char *path,
> @@ -61,6 +79,23 @@ static void check_string_count(const void *fdt, const char *path,
> path, property, err, count);
> }
>
> +static void check_string_index(const void *fdt, const char *path,
> + const char *property, const char *string,
> + int index)
> +{
> + int offset, err;
> +
> + offset = fdt_path_offset(fdt, path);
> + if (offset < 0)
> + FAIL("Couldn't find path %s", path);
> +
> + err = fdt_find_string(fdt, offset, property, string);
> +
> + if (err != index)
> + FAIL("Index of %s in property %s of node %s is %d, expected %d\n",
> + string, property, path, err, index);
> +}
> +
> int main(int argc, char *argv[])
> {
> void *fdt;
> @@ -78,5 +113,10 @@ int main(int argc, char *argv[])
> check_string_count(fdt, "/device", "compatible", 2);
> check_string_count(fdt, "/device", "big-endian", 0);
>
> + check_string_index(fdt, "/", "compatible", "test-strings", 0);
> + check_string_index(fdt, "/device", "compatible", "foo", 0);
> + check_string_index(fdt, "/device", "compatible", "bar", 1);
> + check_string_index(fdt, "/device", "big-endian", "baz", -1);
> +
> PASS();
> }
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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