Add touchf(), formatted version of touch()

Signed-off-by: Joachim Wiberg <troglobit@gmail.com>

README.md

@@ -110,6 +110,10 @@ Helper Macros
 
   Create a file, or update mtime.  Errors on `stderr`
 
+- `touchf(fmt, ...)`
+
+  Like `touch()` but takes a formatted printf-like string as argument.
+
 - `S_ISEXEC(mode_t m)`
 
   Mysteriously missing from GLIBC

src/Makefile.am

@@ -14,7 +14,7 @@ libite_la_SOURCES     = chomp.c		copyfile.c			\
 			reallocarray.c	rsync.c				\
 			strlcpy.c 	strlcat.c 	strtonum.c	\
 			strdupa.h	strndupa.h	strnlen.h	\
-			strmatch.c	systemf.c			\
+			strmatch.c	systemf.c	touchf.c	\
 			telnet.c	tempfile.c	truncatef.c	\
 			yorn.c		which.c				\
 			lite.h		strlite.h			\

src/lite.h

@@ -107,6 +107,8 @@ int     telnet_close   (sdbuf_t *ctx);
 int     telnet_expect  (sdbuf_t *ctx, char *script[], FILE *output);
 int     telnet_session (int addr, short port, char *script[], FILE *output);
 
+int     touchf         (const char *fmt, ...);
+
 int     yorn       (const char *fmt, ...);
 
 char   *which      (const char *cmd);

src/touchf.c

@@ -0,0 +1,66 @@
+/* Formatted touch()
+ *
+ * Copyright (c) 2021  Joachim Wiberg <troglobit@gmail.com>
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include <errno.h>
+#include <stdio.h>
+#include <stdarg.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+#include "lite.h"
+
+/**
+ * touchf - Like touch() but with formatted string support
+ * @fmt:  Formatted string to be composed into a pathname
+ *
+ * This is a wrapper for the touch() function in lite.h, lessening the
+ * burden of having to compose the filename from parts in a seprate
+ * buffer.
+ *
+ * Returns:
+ * Upon successful completion touchf() returns POSIX OK(0), otherwise,
+ * -1 is returned and errno is set to indicate the error.
+ */
+int touchf(const char *fmt, ...)
+{
+	va_list ap;
+	char *file;
+	int len;
+
+	va_start(ap, fmt);
+	len = vsnprintf(NULL, 0, fmt, ap);
+	va_end(ap);
+
+	file = alloca(len + 1);
+	if (!file) {
+		errno = ENOMEM;
+		return -1;
+	}
+
+	va_start(ap, fmt);
+	vsnprintf(file, len + 1, fmt, ap);
+	va_end(ap);
+
+	return touch(file);
+}
+
+/**
+ * Local Variables:
+ *  indent-tabs-mode: t
+ *  c-file-style: "linux"
+ * End:
+ */

tests/touch.c

@@ -6,6 +6,8 @@
 
 #include "check.h"
 
+#define FMT "%s-bar"
+
 int verbose = 0;
 
 
@@ -32,10 +34,30 @@ static int mtime(char *file)
 	ret = timespec_newer(&after.st_mtim, &before.st_mtim);
 	PRINT("Before: %s\n", timespec2str(&before.st_mtim, buf, sizeof(buf)));
 	PRINT("After : %s\n", timespec2str(&after.st_mtim, buf, sizeof(buf)));
+	erase(file);
 
 	return !ret;
 }
 
+static int formatted(char *file)
+{
+	char vrfy[80];
+
+	if (touchf(FMT, file))
+		err(1, "Failed creating " FMT, file);
+
+	PRINT("Created " FMT "\n", file);
+
+	snprintf(vrfy, sizeof(vrfy), FMT, file);
+	if (!fexist(vrfy))
+		errx(1, "touchf() does not detect failure to create file " FMT, file);
+
+	PRINT("File " FMT " really does exist!\n", file);
+	erase(vrfy);
+
+	return 0;
+}
+
 int main(int argc, char *argv[])
 {
 	int fd;
@@ -49,13 +71,13 @@ int main(int argc, char *argv[])
 		err(1, "Failed creating tempfile, %s", file);
 	close(fd);
 
-	return mtime(file);
+	return mtime(file) || formatted(file);
 }
 
 /**
  * Local Variables:
  *  indent-tabs-mode: t
  *  c-file-style:     "linux"
- *  compile-command:  "make pidfile && ./pidfile -v"
+ *  compile-command:  "make touch && ./touch -v"
  * End:
  */