From b21a9d4f10a066cac76bb345d31fdd24afcf3e6f Mon Sep 17 00:00:00 2001
From: Fathi Boudra <fathi.boudra@linaro.org>
Date: Tue, 9 Apr 2024 08:47:37 +0200
Subject: [PATCH] musl: basename: use portable implementation for basename API

musl has removed the non-prototype declaration of basename from string.h which
now results in build errors with newer clang compilers.

Implement GNU basename behavior using strchr which is portable across libcs.

Fixes:
| ../../git/tools/mountcomposefs.c:43:20:
| error: call to undeclared function 'basename'; ISO C99 and later do not
| support implicit function declarations [-Wimplicit-function-declaration]
|    43 |         const char *bin = basename(argv0);
|       |                           ^
| ../../git/tools/mountcomposefs.c:43:14:
| error: incompatible integer to pointer conversion initializing 'const char *'
| with an expression of type 'int' [-Wint-conversion]
|    43 |         const char *bin = basename(argv0);
|       |                     ^     ~~~~~~~~~~~~~~~

For reference:
https://git.musl-libc.org/cgit/musl/commit/?id=725e17ed6dff4d0cd22487bb64470881e86a92e7

Closes: https://github.com/containers/composefs/issues/272

Signed-off-by: Fathi Boudra <fathi.boudra@linaro.org>

Upstream-Status: Submitted [https://github.com/containers/composefs/pull/273]
---
 libcomposefs/lcfs-utils.h |    6 ++++++
 tools/mkcomposefs.c       |    2 +-
 tools/mountcomposefs.c    |    3 ++-
 3 files changed, 9 insertions(+), 2 deletions(-)

--- a/tools/mountcomposefs.c
+++ b/tools/mountcomposefs.c
@@ -37,10 +37,11 @@
 #include <linux/fsverity.h>
 
 #include "libcomposefs/lcfs-mount.h"
+#include "libcomposefs/lcfs-utils.h"
 
 static void usage(const char *argv0)
 {
-	const char *bin = basename(argv0);
+	const char *bin = gnu_basename(argv0);
 	fprintf(stderr,
 		"usage: %s [-t type] [-o opt[,opts..]] IMAGE MOUNTPOINT\n"
 		"Example:\n"
--- a/libcomposefs/lcfs-utils.h
+++ b/libcomposefs/lcfs-utils.h
@@ -161,4 +161,10 @@ static inline void *steal_pointer(void *
 /* type safety */
 #define steal_pointer(pp) (0 ? (*(pp)) : (steal_pointer)(pp))
 
+static inline const char *gnu_basename(const char *filename)
+{
+	const char *p = strrchr(filename, '/');
+	return p ? p+1 : filename;
+}
+
 #endif
--- a/tools/mkcomposefs.c
+++ b/tools/mkcomposefs.c
@@ -315,7 +315,7 @@ static int fill_store(struct lcfs_node_s
 
 static void usage(const char *argv0)
 {
-	const char *bin = basename(argv0);
+	const char *bin = gnu_basename(argv0);
 	fprintf(stderr,
 		"Usage: %s [OPTIONS] SOURCE IMAGE\n"
 		"Options:\n"