From e3e7ccd35a85f9cd38c67cb1988251f1543b6632 Mon Sep 17 00:00:00 2001
From: Michael Graeb <graebm@amazon.com>
Date: Mon, 28 Oct 2019 15:47:07 -0700
Subject: [PATCH] aws_string_c_str() (#534)

---
 include/aws/common/string.h        | 6 ++++++
 include/aws/common/string.inl      | 9 +++++++++
 source/posix/environment.c         | 6 +++---
 source/windows/environment.c       | 6 +++---
 tests/logging/log_formatter_test.c | 2 +-
 5 files changed, 22 insertions(+), 7 deletions(-)

diff --git a/include/aws/common/string.h b/include/aws/common/string.h
index 0fdf81a0c..86d248793 100644
--- a/include/aws/common/string.h
+++ b/include/aws/common/string.h
@@ -217,6 +217,12 @@ int aws_secure_strlen(const char *str, size_t max_read_len, size_t *str_len);
 AWS_STATIC_IMPL
 const uint8_t *aws_string_bytes(const struct aws_string *str);
 
+/**
+ * Equivalent to `(const char *)str->bytes`.
+ */
+AWS_STATIC_IMPL
+const char *aws_string_c_str(const struct aws_string *str);
+
 /**
  * Evaluates the set of properties that define the shape of all valid aws_string structures.
  * It is also a cheap check, in the sense it run in constant time (i.e., no loops or recursion).
diff --git a/include/aws/common/string.inl b/include/aws/common/string.inl
index 4834458d4..32a826993 100644
--- a/include/aws/common/string.inl
+++ b/include/aws/common/string.inl
@@ -27,6 +27,15 @@ const uint8_t *aws_string_bytes(const struct aws_string *str) {
     return str->bytes;
 }
 
+/**
+ * Equivalent to `(const char *)str->bytes`.
+ */
+AWS_STATIC_IMPL
+const char *aws_string_c_str(const struct aws_string *str) {
+    AWS_PRECONDITION(aws_string_is_valid(str));
+    return (const char *)str->bytes;
+}
+
 /**
  * Evaluates the set of properties that define the shape of all valid aws_string structures.
  * It is also a cheap check, in the sense it run in constant time (i.e., no loops or recursion).
diff --git a/source/posix/environment.c b/source/posix/environment.c
index a069c30d0..90a05cd32 100644
--- a/source/posix/environment.c
+++ b/source/posix/environment.c
@@ -23,7 +23,7 @@ int aws_get_environment_value(
     const struct aws_string *variable_name,
     struct aws_string **value_out) {
 
-    const char *value = getenv((const char *)variable_name->bytes);
+    const char *value = getenv(aws_string_c_str(variable_name));
     if (value == NULL) {
         *value_out = NULL;
         return AWS_OP_SUCCESS;
@@ -39,7 +39,7 @@ int aws_get_environment_value(
 
 int aws_set_environment_value(const struct aws_string *variable_name, const struct aws_string *value) {
 
-    if (setenv((const char *)variable_name->bytes, (const char *)value->bytes, 1) != 0) {
+    if (setenv(aws_string_c_str(variable_name), aws_string_c_str(value), 1) != 0) {
         return aws_raise_error(AWS_ERROR_ENVIRONMENT_SET);
     }
 
@@ -47,7 +47,7 @@ int aws_set_environment_value(const struct aws_string *variable_name, const stru
 }
 
 int aws_unset_environment_value(const struct aws_string *variable_name) {
-    if (unsetenv((const char *)variable_name->bytes) != 0) {
+    if (unsetenv(aws_string_c_str(variable_name)) != 0) {
         return aws_raise_error(AWS_ERROR_ENVIRONMENT_UNSET);
     }
 
diff --git a/source/windows/environment.c b/source/windows/environment.c
index 265f02b1c..8c042ddc5 100644
--- a/source/windows/environment.c
+++ b/source/windows/environment.c
@@ -26,7 +26,7 @@ int aws_get_environment_value(
 #pragma warning(push)
 #pragma warning(disable : 4996)
 
-    const char *value = getenv((const char *)variable_name->bytes);
+    const char *value = getenv(aws_string_c_str(variable_name));
 
 #pragma warning(pop)
 
@@ -44,7 +44,7 @@ int aws_get_environment_value(
 }
 
 int aws_set_environment_value(const struct aws_string *variable_name, const struct aws_string *value) {
-    if (_putenv_s((const char *)variable_name->bytes, (const char *)value->bytes) != 0) {
+    if (_putenv_s(aws_string_c_str(variable_name), aws_string_c_str(value)) != 0) {
         return aws_raise_error(AWS_ERROR_ENVIRONMENT_SET);
     }
 
@@ -54,7 +54,7 @@ int aws_set_environment_value(const struct aws_string *variable_name, const stru
 AWS_STATIC_STRING_FROM_LITERAL(s_empty_string, "");
 
 int aws_unset_environment_value(const struct aws_string *variable_name) {
-    if (_putenv_s((const char *)variable_name->bytes, (const char *)s_empty_string->bytes) != 0) {
+    if (_putenv_s(aws_string_c_str(variable_name), aws_string_c_str(s_empty_string)) != 0) {
         return aws_raise_error(AWS_ERROR_ENVIRONMENT_UNSET);
     }
 
diff --git a/tests/logging/log_formatter_test.c b/tests/logging/log_formatter_test.c
index 2db2ef72b..7c8111627 100644
--- a/tests/logging/log_formatter_test.c
+++ b/tests/logging/log_formatter_test.c
@@ -48,7 +48,7 @@ int do_default_log_formatter_test(
     aws_log_formatter_clean_up(&formatter);
 
     char buffer[TEST_FORMATTER_MAX_BUFFER_SIZE];
-    snprintf(buffer, TEST_FORMATTER_MAX_BUFFER_SIZE, "%s", (const char *)output->bytes);
+    snprintf(buffer, TEST_FORMATTER_MAX_BUFFER_SIZE, "%s", aws_string_c_str(output));
 
     aws_string_destroy(output);