Re: [PATCH v3 04/31] lib: Add a way to find the postiion of a trailing number

[Heinrich Schuchardt]

On 1/19/22 02:42, Simon Glass wrote:

At present it is not possible to find out which part of the string is the
number part and which is before it. Add a new variant which provides this
feature, so we can separate the two in the caller.

Signed-off-by: Simon Glass <s...@chromium.org>
---

Changes in v3:
- Change the function to return a pointer to the first digit
- Add some tests, including one for 'abc123def456'

  include/vsprintf.h | 18 ++++++++++++++++++
  lib/strto.c        | 14 ++++++++++++--
  test/str_ut.c      | 13 ++++++++++++-
  3 files changed, 42 insertions(+), 3 deletions(-)

diff --git a/include/vsprintf.h b/include/vsprintf.h
index 01d2248e04d..ce7a7aaa1cc 100644
--- a/include/vsprintf.h
+++ b/include/vsprintf.h
@@ -118,6 +118,24 @@ long trailing_strtol(const char *str);
   */
  long trailing_strtoln(const char *str, const char *end);

+/**
+ * trailing_strtoln_end() - extract trailing integer from a fixed-length string
+ *
+ * Given a fixed-length string this finds a trailing number on the string
+ * and returns it. For example, "abc123" would return 123. Only the
+ * characters between @str and @end - 1 are examined. If @end is NULL, it is
+ * set to str + strlen(str).
+ *
+ * @str:       String to exxamine
+ * @end:       Pointer to end of string to examine, or NULL to use the
+ *             whole string
+ * @endp:      If non-NULL, this is set to point to the character where the
+ *     number starts, e.g. for "mmc0" this would be point to the '0'; if no
+ *     trailing number is found, it is set to the end of the string
+ * @return training number if found, else -1

Return:

https://www.kernel.org/doc/html/latest/doc-guide/kernel-doc.html#function-documentation

Best regards

Heinrich

+ */
+long trailing_strtoln_end(const char *str, const char *end, char const **endp);
+
  /**
   * panic() - Print a message and reset/hang
   *
diff --git a/lib/strto.c b/lib/strto.c
index 58fc10ecaea..72cfef660fc 100644
--- a/lib/strto.c
+++ b/lib/strto.c
@@ -183,7 +183,7 @@ long long simple_strtoll(const char *cp, char **endp, 
unsigned int base)
        return simple_strtoull(cp, endp, base);
  }

-long trailing_strtoln(const char *str, const char *end)
+long trailing_strtoln_end(const char *str, const char *end, char const **endp)
  {
        const char *p;

@@ -192,14 +192,24 @@ long trailing_strtoln(const char *str, const char *end)
        p = end - 1;
        if (p > str && isdigit(*p)) {
                do {
-                       if (!isdigit(p[-1]))
+                       if (!isdigit(p[-1])) {
+                               if (endp)
+                                       *endp = p;
                                return dectoul(p, NULL);
+                       }
                } while (--p > str);
        }
+       if (endp)
+               *endp = end;

        return -1;
  }

+long trailing_strtoln(const char *str, const char *end)
+{
+       return trailing_strtoln_end(str, end, NULL);
+}
+
  long trailing_strtol(const char *str)
  {
        return trailing_strtoln(str, NULL);
diff --git a/test/str_ut.c b/test/str_ut.c
index 058b3594379..5a844347c2b 100644
--- a/test/str_ut.c
+++ b/test/str_ut.c
@@ -244,7 +244,9 @@ STR_TEST(str_xtoa, 0);

  static int str_trailing(struct unit_test_state *uts)
  {
-       char str1[] = "abc123def";
+       const char str1[] = "abc123def";
+       const char str2[] = "abc123def456";
+       const char *end;

        ut_asserteq(-1, trailing_strtol(""));
        ut_asserteq(-1, trailing_strtol("123"));
@@ -259,6 +261,15 @@ static int str_trailing(struct unit_test_state *uts)

        ut_asserteq(3, trailing_strtol("a3"));

+       ut_asserteq(123, trailing_strtoln_end(str1, str1 + 6, &end));
+       ut_asserteq(3, end - str1);
+
+       ut_asserteq(-1, trailing_strtoln_end(str1, str1 + 7, &end));
+       ut_asserteq(7, end - str1);
+
+       ut_asserteq(456, trailing_strtoln_end(str2, NULL, &end));
+       ut_asserteq(9, end - str2);
+
        return 0;
  }
  STR_TEST(str_trailing, 0);