util: Add spdk_strcpy_replace() to replace substrings

spdk_nvme_cpl_get_status_string() returns a string which contains upper
cases, spaces, and hyphens. To use the returned string for JSON RPC, we
have to convert it to a string which contains only lowercases and
underscores.

For our convenience, add a new API spdk_strcpy_replace() to replace
all occurrences of the search string with the replacement string.

Signed-off-by: Shuhei Matsumoto <smatsumoto@nvidia.com>
Change-Id: I3ca9774d0bfb2d0bb7bd7412bc671e6f69104b7d
Reviewed-on: https://review.spdk.io/gerrit/c/spdk/spdk/+/16054
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>
Community-CI: Mellanox Build Bot
Reviewed-by: Konrad Sztyber <konrad.sztyber@intel.com>
Reviewed-by: Aleksey Marchuk <alexeymar@nvidia.com>
Reviewed-by: Jim Harris <james.r.harris@intel.com>

CHANGELOG.md

@@ -85,6 +85,9 @@ available trace point groups and mask of the available trace points for each gro
 New API `spdk_fd_group_get_epoll_event` that returns the epoll(7) event that
 caused a function callback in file descriptor group to execute.
 
+A new API `spdk_strcpy_replace` was added to replace all occurrences of the search string
+with the replacement string.
+
 ### json
 
 Added API `spdk_json_write_double` and `spdk_json_write_named_double` to allow

include/spdk/string.h

@@ -1,5 +1,6 @@
 /*   SPDX-License-Identifier: BSD-3-Clause
  *   Copyright (C) 2015 Intel Corporation.
+ *   Copyright (c) 2022, NVIDIA CORPORATION & AFFILIATES.
  *   All rights reserved.
  */
 
@@ -265,6 +266,22 @@ char **spdk_strarray_dup(const char **strarray);
  */
 void spdk_strarray_free(char **strarray);
 
+/**
+ * Copy a string into a fixed-size buffer with all occurrences of the search string
+ * replaced with the given replace substring. The fixed-size buffer must not be less
+ * than the string with the replaced values including the terminating null byte.
+ *
+ * \param dst Pointer to destination fixed-size buffer to fill.
+ * \param size Size of the destination fixed-size buffer in bytes.
+ * \param src Pointer to source null-terminated string to copy into dst.
+ * \param search The string being searched for.
+ * \param replace the replacement substring the replaces the found search substring.
+ *
+ * \return 0 on success, or negated errno on failure.
+ */
+int spdk_strcpy_replace(char *dst, size_t size, const char *src, const char *search,
+			const char *replace);
+
 #ifdef __cplusplus
 }
 #endif

lib/util/spdk_util.map

@@ -126,6 +126,7 @@
 	spdk_strarray_from_string;
 	spdk_strarray_dup;
 	spdk_strarray_free;
+	spdk_strcpy_replace;
 
 	# public functions in util.h
 	spdk_u32log2;

lib/util/string.c

@@ -1,5 +1,6 @@
 /*   SPDX-License-Identifier: BSD-3-Clause
  *   Copyright (C) 2015 Intel Corporation.
+ *   Copyright (c) 2022, NVIDIA CORPORATION & AFFILIATES.
  *   All rights reserved.
  */
 
@@ -542,3 +543,49 @@ spdk_strarray_dup(const char **strarray)
 
 	return result;
 }
+
+int
+spdk_strcpy_replace(char *dst, size_t size, const char *src, const char *search,
+		    const char *replace)
+{
+	const char *p, *q;
+	char *r;
+	size_t c, search_size, replace_size, dst_size;
+
+	if (dst == NULL || src == NULL || search == NULL || replace == NULL) {
+		return -EINVAL;
+	}
+
+	search_size = strlen(search);
+	replace_size = strlen(replace);
+
+	c = 0;
+	for (p = strstr(src, search); p != NULL; p = strstr(p + search_size, search)) {
+		c++;
+	}
+
+	dst_size = strlen(src) + (replace_size - search_size) * c;
+	if (dst_size >= size) {
+		return -EINVAL;
+	}
+
+	q = src;
+	r = dst;
+
+	for (p = strstr(src, search); p != NULL; p = strstr(p + search_size, search)) {
+		memcpy(r, q, p - q);
+		r += p - q;
+
+		memcpy(r, replace, replace_size);
+		r += replace_size;
+
+		q = p + search_size;
+	}
+
+	memcpy(r, q, strlen(q));
+	r += strlen(q);
+
+	*r = '\0';
+
+	return 0;
+}

test/unit/lib/util/string.c/string_ut.c

@@ -1,5 +1,6 @@
 /*   SPDX-License-Identifier: BSD-3-Clause
  *   Copyright (C) 2017 Intel Corporation.
+ *   Copyright (c) 2022, NVIDIA CORPORATION & AFFILIATES.
  *   All rights reserved.
  */
 
@@ -436,6 +437,72 @@ test_strarray(void)
 	spdk_strarray_free(r2);
 }
 
+static void
+test_strcpy_replace(void)
+{
+	const char *original = "good morning, hello, thank you";
+	const char *search1 = "evening";
+	const char *replace1 = "unexpected";
+	const char *search2 = "morning";
+	const char *replace2 = "afternoon";
+	const char *expected2 = "good afternoon, hello, thank you";
+	const char *search3 = "morning";
+	const char *replace3 = "night";
+	const char *expected3 = "good night, hello, thank you";
+	const char *search4 = "hello";
+	const char *replace4 = "good bye";
+	const char *expected4 = "good morning, good bye, thank you";
+	const char *search5 = "thank you";
+	const char *replace5 = "you are welcome";
+	const char *expected5 = "good morning, hello, you are welcome";
+	const char *search6 = " ";
+	const char *replace6 = "-";
+	const char *expected6 = "good-morning,-hello,-thank-you";
+	const char *search7 = ",";
+	const char *replace7 = ".";
+	const char *expected7 = "good morning. hello. thank you";
+	char result[256];
+	int rc;
+
+	rc = spdk_strcpy_replace(NULL, 0, NULL, NULL, NULL);
+	CU_ASSERT(rc == -EINVAL);
+
+	rc = spdk_strcpy_replace(result, sizeof(result), original, search1, replace1);
+	CU_ASSERT(rc == 0);
+	CU_ASSERT(strcmp(result, original) == 0);
+
+	rc = spdk_strcpy_replace(result, sizeof(result), original, search2, replace2);
+	CU_ASSERT(rc == 0);
+	CU_ASSERT(strcmp(result, expected2) == 0);
+
+	/* A case that sizeof(replace) is less than sizeof(search), and the result array is
+	 * smaller than the original string. */
+	rc = spdk_strcpy_replace(result, strlen(expected3) + 1, original, search3, replace3);
+	CU_ASSERT(rc == 0);
+	CU_ASSERT(strcmp(result, expected3) == 0);
+
+	/* An error case that the result array is smaller than the string with replaced values
+	 * and a terminated null byte. */
+	rc = spdk_strcpy_replace(result, strlen(expected3), original, search3, replace3);
+	CU_ASSERT(rc == -EINVAL);
+
+	rc = spdk_strcpy_replace(result, sizeof(result), original, search4, replace4);
+	CU_ASSERT(rc == 0);
+	CU_ASSERT(strcmp(result, expected4) == 0);
+
+	rc = spdk_strcpy_replace(result, sizeof(result), original, search5, replace5);
+	CU_ASSERT(rc == 0);
+	CU_ASSERT(strcmp(result, expected5) == 0);
+
+	rc = spdk_strcpy_replace(result, sizeof(result), original, search6, replace6);
+	CU_ASSERT(rc == 0);
+	CU_ASSERT(strcmp(result, expected6) == 0);
+
+	rc = spdk_strcpy_replace(result, sizeof(result), original, search7, replace7);
+	CU_ASSERT(rc == 0);
+	CU_ASSERT(strcmp(result, expected7) == 0);
+}
+
 int
 main(int argc, char **argv)
 {
@@ -454,6 +521,7 @@ main(int argc, char **argv)
 	CU_ADD_TEST(suite, test_strtol);
 	CU_ADD_TEST(suite, test_strtoll);
 	CU_ADD_TEST(suite, test_strarray);
+	CU_ADD_TEST(suite, test_strcpy_replace);
 
 	CU_basic_set_mode(CU_BRM_VERBOSE);