[PATCH] Add startswith function and use it instead of CONST_STRNEQ.

[Alan Modra]

On Sat, Mar 20, 2021 at 12:58:10PM -0600, Tom Tromey wrote:
> >>>>> "Alan" == Alan Modra via Binutils <binutils@sourceware.org> writes:
> 
> Alan> Forcing gdb to remove their startswith is a bit rude.
> 
> FWIW I think it would be fine, assuming it compiles, considering that
> the functions have identical intended semantics.

Yes, the following compiles.  Fortunately all gdb files that include
gdbsupport/common-utils.h also include bfd.h by one means or another.

Committed.

bfd/
	* bfd-in.h (startswith): New inline.
	(CONST_STRNEQ): Use startswith.
	* bfd-in2.h: Regenerate.
gdbsupport/
	* common-utils.h (startswith): Delete version now supplied by bfd.h.
libctf/
	* ctf-impl.h: Include string.h.

diff --git a/bfd/bfd-in.h b/bfd/bfd-in.h
index c9a7673147..453ac48e26 100644
--- a/bfd/bfd-in.h
+++ b/bfd/bfd-in.h
@@ -65,7 +65,6 @@ extern "C" {
    definition of strncmp is provided here.
 
    Note - these macros do NOT work if STR2 is not a constant string.  */
-#define CONST_STRNEQ(STR1,STR2) (strncmp ((STR1), (STR2), sizeof (STR2) - 1) == 0)
   /* strcpy() can have a similar problem, but since we know we are
      copying a constant string, we can use memcpy which will be faster
      since there is no need to check for a NUL byte inside STR.  We
@@ -564,3 +563,12 @@ struct ecoff_debug_swap;
 struct ecoff_extr;
 struct bfd_link_info;
 struct bfd_link_hash_entry;
+
+/* Return TRUE if the start of STR matches PREFIX, FALSE otherwise.  */
+
+static inline bfd_boolean
+startswith (const char *str, const char *prefix)
+{
+  return strncmp (str, prefix, strlen (prefix)) == 0;
+}
+#define CONST_STRNEQ(STR1,STR2) startswith (STR1, STR2)
diff --git a/gdbsupport/common-utils.h b/gdbsupport/common-utils.h
index 28c08ee976..1de747f186 100644
--- a/gdbsupport/common-utils.h
+++ b/gdbsupport/common-utils.h
@@ -116,16 +116,8 @@ std::string extract_string_maybe_quoted (const char **arg);
 
 extern const char *safe_strerror (int);
 
-/* Return true if the start of STRING matches PATTERN, false otherwise.  */
-
-static inline bool
-startswith (const char *string, const char *pattern)
-{
-  return strncmp (string, pattern, strlen (pattern)) == 0;
-}
-
-/* Version of startswith that takes string_view arguments.  See comment
-   above.  */
+/* Version of startswith that takes string_view arguments.  Return
+   true if the start of STRING matches PATTERN, false otherwise.  */
 
 static inline bool
 startswith (gdb::string_view string, gdb::string_view pattern)
diff --git a/libctf/ctf-impl.h b/libctf/ctf-impl.h
index ad4af32e7e..342d2ff23e 100644
--- a/libctf/ctf-impl.h
+++ b/libctf/ctf-impl.h
@@ -32,6 +32,7 @@
 #include <stddef.h>
 #include <stdio.h>
 #include <stdint.h>
+#include <string.h>
 #include <limits.h>
 #include <ctype.h>
 #include <elf.h>

-- 
Alan Modra
Australia Development Lab, IBM