devicetree-compiler.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Thierry Reding <thierry.reding-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
To: David Gibson
	<david-xT8FGy+AXnRB3Ne2BGzF6laj5H9X9Tb+@public.gmane.org>,
	Jon Loeliger <jdl-CYoMK+44s/E@public.gmane.org>
Cc: devicetree-compiler-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	Simon Glass <sjg-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>,
	Masahiro Yamada
	<yamada.masahiro-uWyLwvC0a2jby3iVrkZq2A@public.gmane.org>
Subject: [PATCH v2 3/3] fdt: Add functions to retrieve strings
Date: Thu, 16 Jul 2015 13:10:21 +0200	[thread overview]
Message-ID: <1437045021-4549-4-git-send-email-thierry.reding@gmail.com> (raw)
In-Reply-To: <1437045021-4549-1-git-send-email-thierry.reding-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>

From: Thierry Reding <treding-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>

Given a device tree node, a property name and an index, the new function
fdt_get_string_index() will return in an output argument a pointer to
the index'th string in the property's value.

The fdt_get_string() is a shortcut for the above with the index being 0.

Signed-off-by: Thierry Reding <treding-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
---
Changes in v2:
- handle non-NUL-terminated properties more gracefully
- improve documentation

 libfdt/fdt_ro.c | 37 +++++++++++++++++++++++++++++++++++++
 libfdt/libfdt.h | 41 +++++++++++++++++++++++++++++++++++++++++
 tests/strings.c | 32 ++++++++++++++++++++++++++++++++
 3 files changed, 110 insertions(+)

diff --git a/libfdt/fdt_ro.c b/libfdt/fdt_ro.c
index 39b84b1cea60..4315815969b6 100644
--- a/libfdt/fdt_ro.c
+++ b/libfdt/fdt_ro.c
@@ -593,6 +593,43 @@ int fdt_find_string(const void *fdt, int nodeoffset, const char *property,
 	return -FDT_ERR_NOTFOUND;
 }
 
+int fdt_get_string_index(const void *fdt, int nodeoffset, const char *property,
+			 int index, const char **output)
+{
+	const char *list, *end;
+	int length;
+
+	list = fdt_getprop(fdt, nodeoffset, property, &length);
+	if (!list)
+		return -length;
+
+	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 (index == 0) {
+			*output = list;
+			return 0;
+		}
+
+		list += length;
+		index--;
+	}
+
+	return -FDT_ERR_NOTFOUND;
+}
+
+int fdt_get_string(const void *fdt, int nodeoffset, const char *property,
+		   const char **output)
+{
+	return fdt_get_string_index(fdt, nodeoffset, property, 0, output);
+}
+
 int fdt_node_check_compatible(const void *fdt, int nodeoffset,
 			      const char *compatible)
 {
diff --git a/libfdt/libfdt.h b/libfdt/libfdt.h
index e64680dd741c..bfbc8f9ead34 100644
--- a/libfdt/libfdt.h
+++ b/libfdt/libfdt.h
@@ -907,6 +907,47 @@ int fdt_count_strings(const void *fdt, int nodeoffset, const char *property);
 int fdt_find_string(const void *fdt, int nodeoffset, const char *property,
 		    const char *string);
 
+/**
+ * fdt_get_string_index() - 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
+ * @output: return location for the string
+ *
+ * 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.
+ *
+ * The @output parameter is only valid if the function returns 0.
+ *
+ * @return:
+ *   0 if the string was found (@output points to the string)
+ *   -FDT_ERR_BADVALUE if the property value is not NUL-terminated
+ *   -FDT_ERR_NOTFOUND if the property does not exist
+ */
+int fdt_get_string_index(const void *fdt, int nodeoffset, const char *property,
+			 int index, const char **output);
+
+/**
+ * fdt_get_string() - obtain the first string 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
+ * @output: return location for the string
+ *
+ * This is a shorthand for:
+ *
+ *   fdt_get_string_index(fdt, node, property, 0, output).
+ *
+ * @return:
+ *   0 if the string was found (@output points to the string)
+ *   -FDT_ERR_BADVALUE if the property value is not NUL-terminated
+ *   -FDT_ERR_NOTFOUND if the property does not exist
+ */
+int fdt_get_string(const void *fdt, int nodeoffset, const char *property,
+		   const char **output);
+
 /**********************************************************************/
 /* Read-only functions (addressing related)                           */
 /**********************************************************************/
diff --git a/tests/strings.c b/tests/strings.c
index 29c49bfcc78c..aa83ef0511be 100644
--- a/tests/strings.c
+++ b/tests/strings.c
@@ -58,6 +58,13 @@ static void check_expected_failure(const void *fdt, const char *path,
 	err = fdt_find_string(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, index);
 }
 
+static void check_string(const void *fdt, const char *path,
+			 const char *property, int index,
+			 const char *string)
+{
+	const char *result;
+	int offset, err;
+
+	offset = fdt_path_offset(fdt, path);
+	if (offset < 0)
+		FAIL("Couldn't find path %s", path);
+
+	err = fdt_get_string_index(fdt, offset, property, index, &result);
+	if (err < 0)
+		FAIL("Couldn't extract string %d from property %s of node %s: %d\n",
+		     index, property, path, err);
+
+	if (strcmp(string, result) != 0)
+		FAIL("String %d in property %s of node %s is %s, expected %s\n",
+		     index, 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();
 }
-- 
2.4.5

  parent reply	other threads:[~2015-07-16 11:10 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-07-16 11:10 [PATCH v2 0/3] Add a couple of string-related functions Thierry Reding
     [not found] ` <1437045021-4549-1-git-send-email-thierry.reding-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2015-07-16 11:10   ` [PATCH v2 1/3] fdt: Add a function to count strings Thierry Reding
     [not found]     ` <1437045021-4549-2-git-send-email-thierry.reding-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2015-09-29  5:53       ` David Gibson
     [not found]         ` <20150929055313.GP19428-1s0os16eZneny3qCrzbmXA@public.gmane.org>
2015-09-29  8:32           ` Thierry Reding
2015-07-16 11:10   ` [PATCH v2 2/3] fdt: Add a function to get the index of a string Thierry Reding
     [not found]     ` <1437045021-4549-3-git-send-email-thierry.reding-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2015-09-29  5:54       ` David Gibson
     [not found]         ` <20150929055446.GQ19428-1s0os16eZneny3qCrzbmXA@public.gmane.org>
2015-09-29  8:32           ` Thierry Reding
2015-07-16 11:10   ` Thierry Reding [this message]
     [not found]     ` <1437045021-4549-4-git-send-email-thierry.reding-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2015-09-29  6:00       ` [PATCH v2 3/3] fdt: Add functions to retrieve strings David Gibson
     [not found]         ` <20150929060041.GR19428-1s0os16eZneny3qCrzbmXA@public.gmane.org>
2015-09-29  9:10           ` Thierry Reding
2015-09-29  5:50   ` [PATCH v2 0/3] Add a couple of string-related functions David Gibson

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=1437045021-4549-4-git-send-email-thierry.reding@gmail.com \
    --to=thierry.reding-re5jqeeqqe8avxtiumwx3w@public.gmane.org \
    --cc=david-xT8FGy+AXnRB3Ne2BGzF6laj5H9X9Tb+@public.gmane.org \
    --cc=devicetree-compiler-u79uwXL29TY76Z2rM5mHXA@public.gmane.org \
    --cc=jdl-CYoMK+44s/E@public.gmane.org \
    --cc=sjg-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org \
    --cc=yamada.masahiro-uWyLwvC0a2jby3iVrkZq2A@public.gmane.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).