From 604e61e081e3c6c8fa1a8189c71cb3908a5bbc1e Mon Sep 17 00:00:00 2001 From: Thierry Reding Date: Tue, 29 Sep 2015 11:09:08 +0200 Subject: [PATCH] fdt: Add functions to retrieve strings Given a device tree node, a property name and an index, the new function fdt_stringlist_get() will return a pointer to the index'th string in the property's value and return its length (or an error code on failure) in an output argument. Signed-off-by: Thierry Reding [Fix some -Wshadow warnings --dwg] Signed-off-by: David Gibson --- libfdt/fdt_ro.c | 45 +++++++++++++++++++++++++++++++++++++++++++++ libfdt/libfdt.h | 28 ++++++++++++++++++++++++++++ tests/stringlist.c | 32 ++++++++++++++++++++++++++++++++ 3 files changed, 105 insertions(+) diff --git a/libfdt/fdt_ro.c b/libfdt/fdt_ro.c index 2d74c37..e5b3136 100644 --- a/libfdt/fdt_ro.c +++ b/libfdt/fdt_ro.c @@ -593,6 +593,51 @@ int fdt_stringlist_search(const void *fdt, int nodeoffset, const char *property, return -FDT_ERR_NOTFOUND; } +const char *fdt_stringlist_get(const void *fdt, int nodeoffset, + const char *property, int idx, + int *lenp) +{ + const char *list, *end; + int length; + + list = fdt_getprop(fdt, nodeoffset, property, &length); + if (!list) { + if (lenp) + *lenp = length; + + return NULL; + } + + 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) { + if (lenp) + *lenp = -FDT_ERR_BADVALUE; + + return NULL; + } + + if (idx == 0) { + if (lenp) + *lenp = length - 1; + + return list; + } + + list += length; + idx--; + } + + if (lenp) + *lenp = -FDT_ERR_NOTFOUND; + + return NULL; +} + int fdt_node_check_compatible(const void *fdt, int nodeoffset, const char *compatible) { diff --git a/libfdt/libfdt.h b/libfdt/libfdt.h index aa376b8..78adb12 100644 --- a/libfdt/libfdt.h +++ b/libfdt/libfdt.h @@ -907,6 +907,34 @@ int fdt_stringlist_count(const void *fdt, int nodeoffset, const char *property); int fdt_stringlist_search(const void *fdt, int nodeoffset, const char *property, const char *string); +/** + * fdt_stringlist_get() - obtain the string at a given index in a string list + * @fdt: pointer to the device tree blob + * @nodeoffset: offset of a tree node + * @property: name of the property containing the string list + * @index: index of the string to return + * @lenp: return location for the string length or an error code on failure + * + * Note that this will successfully extract strings from properties with + * non-NUL-terminated values. For example on small-valued cell properties + * this function will return the empty string. + * + * If non-NULL, the length of the string (on success) or a negative error-code + * (on failure) will be stored in the integer pointer to by lenp. + * + * @return: + * A pointer to the string at the given index in the string list or NULL on + * failure. On success the length of the string will be stored in the memory + * location pointed to by the lenp parameter, if non-NULL. On failure one of + * the following negative error codes will be returned in the lenp parameter + * (if non-NULL): + * -FDT_ERR_BADVALUE if the property value is not NUL-terminated + * -FDT_ERR_NOTFOUND if the property does not exist + */ +const char *fdt_stringlist_get(const void *fdt, int nodeoffset, + const char *property, int index, + int *lenp); + /**********************************************************************/ /* Read-only functions (addressing related) */ /**********************************************************************/ diff --git a/tests/stringlist.c b/tests/stringlist.c index b8835b7..a9d3e73 100644 --- a/tests/stringlist.c +++ b/tests/stringlist.c @@ -58,6 +58,13 @@ static void check_expected_failure(const void *fdt, const char *path, err = fdt_stringlist_search(fdt, offset, "#address-cells", ""); if (err != 0) FAIL("empty string not found in #address-cells: %d\n", err); + + /* + * fdt_get_string() can successfully extract strings from non-string + * properties. This is because it doesn't necessarily parse the whole + * property value, which would be necessary for it to determine if a + * valid string or string list is present. + */ } static void check_string_count(const void *fdt, const char *path, @@ -96,6 +103,27 @@ static void check_string_index(const void *fdt, const char *path, string, property, path, err, idx); } +static void check_string(const void *fdt, const char *path, + const char *property, int idx, + const char *string) +{ + const char *result; + int offset, len; + + offset = fdt_path_offset(fdt, path); + if (offset < 0) + FAIL("Couldn't find path %s", path); + + result = fdt_stringlist_get(fdt, offset, property, idx, &len); + if (!result) + FAIL("Couldn't extract string %d from property %s of node %s: %d\n", + idx, property, path, len); + + if (strcmp(string, result) != 0) + FAIL("String %d in property %s of node %s is %s, expected %s\n", + idx, property, path, result, string); +} + int main(int argc, char *argv[]) { void *fdt; @@ -118,5 +146,9 @@ int main(int argc, char *argv[]) check_string_index(fdt, "/device", "compatible", "bar", 1); check_string_index(fdt, "/device", "big-endian", "baz", -1); + check_string(fdt, "/", "compatible", 0, "test-strings"); + check_string(fdt, "/device", "compatible", 0, "foo"); + check_string(fdt, "/device", "compatible", 1, "bar"); + PASS(); }