From: Alejandro Colomar <alx@kernel.org>
Date: Wed, 23 Jul 2025 12:19:52 +0000 (+0200)
Subject: lib/io/fprintf.h: [v]fprintec(): Add functions
X-Git-Tag: 4.20.0-rc3~30
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=b9bb887fbb72a24d85b6d19414d5e18e2205eca1;p=thirdparty%2Fshadow.git

lib/io/fprintf.h: [v]fprintec(): Add functions

These functions print a formatted string, followed by a colon and
a space, followed by an error string produced by strerror($2).  That is,
the output is as follows:

	fmt: error message string

For example,
	fprintec(stderr, ENOMEM, "foo(%d)", 42);
prints
	foo(42): Cannot allocate memory

These functions return the number of characters printed, or a negative
value on error, like fprintf(3).

Signed-off-by: Alejandro Colomar <alx@kernel.org>
---

diff --git a/lib/Makefile.am b/lib/Makefile.am
index 599cb0bbd..2995cca66 100644
--- a/lib/Makefile.am
+++ b/lib/Makefile.am
@@ -105,6 +105,8 @@ libshadow_la_SOURCES = \
 	idmapping.c \
 	io/fgets/fgets.c \
 	io/fgets/fgets.h \
+	io/fprintf.c \
+	io/fprintf.h \
 	io/syslog.c \
 	io/syslog.h \
 	isexpired.c \
diff --git a/lib/io/fprintf.c b/lib/io/fprintf.c
new file mode 100644
index 000000000..452d8dd85
--- /dev/null
+++ b/lib/io/fprintf.c
@@ -0,0 +1,16 @@
+// SPDX-FileCopyrightText: 2025, Alejandro Colomar <alx@kernel.org>
+// SPDX-License-Identifier: BSD-3-Clause
+
+
+#include "config.h"
+
+#include "io/fprintf.h"
+
+#include <stdarg.h>
+#include <stdio.h>
+
+
+extern inline int fprintec(FILE *restrict stream, int e,
+    const char *restrict fmt, ...);
+extern inline int vfprintec(FILE *restrict stream, int e,
+    const char *restrict fmt, va_list ap);
diff --git a/lib/io/fprintf.h b/lib/io/fprintf.h
new file mode 100644
index 000000000..356d72151
--- /dev/null
+++ b/lib/io/fprintf.h
@@ -0,0 +1,63 @@
+// SPDX-FileCopyrightText: 2025, Alejandro Colomar <alx@kernel.org>
+// SPDX-License-Identifier: BSD-3-Clause
+
+
+#ifndef SHADOW_INCLUDE_LIB_IO_FPRINTF_H_
+#define SHADOW_INCLUDE_LIB_IO_FPRINTF_H_
+
+
+#include "config.h"
+
+#include <stdarg.h>
+#include <stdio.h>
+#include <string.h>
+
+#include "attr.h"
+
+
+format_attr(printf, 3, 4)
+inline int fprintec(FILE *restrict stream, int e,
+    const char *restrict fmt, ...);
+format_attr(printf, 3, 0)
+inline int vfprintec(FILE *restrict stream, int e,
+    const char *restrict fmt, va_list ap);
+
+
+// fprintec - FILE* print errno code
+inline int
+fprintec(FILE *restrict stream, int e, const char *restrict fmt, ...)
+{
+	int      len;
+	va_list  ap;
+
+	va_start(ap, fmt);
+	len = vfprintec(stream, e, fmt, ap);
+	va_end(ap);
+
+	return len;
+}
+
+
+// vfprintec - va_list FILE* print errno code
+inline int
+vfprintec(FILE *restrict stream, int e, const char *restrict fmt, va_list ap)
+{
+	int  l1, l2, l3;
+
+	l1 = vfprintf(stream, fmt, ap);
+	if (l1 < 0)
+		return l1;
+
+	l2 = fprintf(stream, l1 ? ": " : "");
+	if (l2 < 0)
+		return l2;
+
+	l3 = fprintf(stream, "%s\n", strerror(e));
+	if (l3 < 0)
+		return l3;
+
+	return l1 + l2 + l3;
+}
+
+
+#endif  // include guard