Use case-insensitive comparison for headers fix #2100 (#2101)

* Use case-inseneitive comparison for headers

HTTP headers should be case-insensitive. Use case-insensitive string
comparisons when working with HTTP header responses to ensure
compatibility.

* Revert "Use case-inseneitive comparison for headers"

This reverts commit a02f591723506b62b7208449be6eef7122120398

* Ignore case when searching HTTP header responses

Looking up the Content-Length in the header returned by S3 storage
endpoints should ignore case. To guarantee portability implement a
function for case-insensitive string search, because it is non-standard.

* Add an _ after H5 for the strcasestr implementation

It is a private function and should sport that underscore.

* Remove author comment from the doc comment

* Use search function defined by system if available

Check whether the system provides a function implementing case
insensitive string searches. Only use the custom implementation if the
system does not provide the functionality.

* Add tests for case-insensitive search

Basic tests:
  - Search for empty string
  - Search with exact match
  - Search with case-insensitive match
  - search with no match

* Enforce clang-format style

Some variable definitions in the th5_system tests did not conform to
clang-format's expectations. Updated the offending lines.

* Correct comment describing test case

* Added some spaces to please clang-format

* Ignore discarding const

Ask the compiler to ignore discarding the const when retunring a match from H5_strcasestr

Co-authored-by: Frank Berghaus <frank.berghaus@mpcdf.mpg.de>

1 files changed, 26 insertions, 0 deletions

diff --git a/test/th5_system.c b/test/th5_system.c
index 09570cf..784cb3f 100644
--- a/test/th5_system.c
+++ b/test/th5_system.c
@@ -438,6 +438,31 @@ test_h5_basename(void)
 }
 
 static void
+test_h5_strcasestr(void)
+{
+    const char *const haystack = "My test string";
+    char             *str      = NULL;
+
+    MESSAGE(5, ("Testing H5_strcasestr\n"));
+
+    /* check that H5_strcasestr returns target in empty search */
+    str = H5_strcasestr(haystack, "");
+    CHECK_PTR_EQ(str, haystack, "H5_strcasestr search for empty");
+
+    /* Check that H5_strcasestr find a string of same case */
+    str = H5_strcasestr(haystack, "string");
+    CHECK_PTR_EQ(str, &(haystack[8]), "H5_strcasestr search same case");
+
+    /* Check that H5_strcasestr find a string of different case */
+    str = H5_strcasestr(haystack, "sTrInG");
+    CHECK_PTR_EQ(str, &(haystack[8]), "H5_strcasestr search different case");
+
+    /* Check that H5_strcasestr returns NULL if no match is found */
+    str = H5_strcasestr(haystack, "nomatch");
+    CHECK_PTR_NULL(str, "H5_strcasestr search with no match");
+}
+
+static void
 test_h5_strndup(void)
 {
 #ifdef H5_HAVE_WIN32_API
@@ -495,6 +520,7 @@ test_h5_system(void)
 
     test_h5_dirname();
     test_h5_basename();
+    test_h5_strcasestr();
     test_h5_strndup();
 }