tests: extend readlink and readlinkat coverage

* tests/readlink.c (PREFIX, TARGET, LINKPATH): New macros.
(main): Allocate memory for string and buffer passed to the syscall
being tested using tail_alloc mechanism.  Create and cleanup test
symlink.  Test syscall error path output.  Print hexquoted strings
using hexquote_strndup.
* tests/readlinkat.c: Likewise.
* tests/readlink.test: Remove creation and cleanup of test symlinks.

Author: ldv-alt

tests/readlink.c

@@ -34,25 +34,41 @@
 # include <stdio.h>
 # include <unistd.h>
 
+# define PREFIX "test.readlink"
+# define TARGET (PREFIX ".target")
+# define LINKPATH (PREFIX ".link")
+
 int
 main(void)
 {
-	static const char fname[] = "readlink.link";
-	unsigned char buf[31];
-	long rc;
-	unsigned int i;
+	const char * const fname = tail_memdup(LINKPATH, sizeof(LINKPATH));
+	const char * const hex_fname =
+		hexquote_strndup(fname, sizeof(LINKPATH) - 1);
+
+	const unsigned int size = sizeof(TARGET) - 1;
+	char * const buf = tail_alloc(size);
+
+	(void) unlink(fname);
+
+	long rc = syscall(__NR_readlink, fname, buf, size);
+	printf("readlink(\"%s\", %p, %u) = -1 ENOENT (%m)\n",
+	       hex_fname, buf, size);
+
+	if (symlink(TARGET, fname))
+		perror_msg_and_fail("symlink");
 
-	rc = syscall(__NR_readlink, fname, buf, sizeof(buf));
-	if (rc < 0)
-		perror_msg_and_skip("readlink");
+	rc = syscall(__NR_readlink, fname, buf, size);
+	if (rc < 0) {
+		perror("readlink");
+		(void) unlink(fname);
+		return 77;
+	}
+	const char * const hex_buf = hexquote_strndup(buf, size);
+	printf("readlink(\"%s\", \"%s\", %u) = %u\n",
+	       hex_fname, hex_buf, size, size);
 
-	printf("readlink(\"");
-	for (i = 0; fname[i]; ++i)
-		printf("\\x%02x", (int) (unsigned char) fname[i]);
-	printf("\", \"");
-	for (i = 0; i < 3; ++i)
-		printf("\\x%02x", (int) buf[i]);
-	printf("\"..., %zu) = %ld\n", sizeof(buf), rc);
+	if (unlink(fname))
+		perror_msg_and_fail("unlink");
 
 	puts("+++ exited with 0 +++");
 	return 0;

tests/readlink.test

@@ -5,17 +5,10 @@
 . "${srcdir=.}/init.sh"
 
 syscall=${ME_%.test}
-target=$syscall.c
-link=$syscall.link
 OUT="$LOG.out"
 
-ln -snf $target $link ||
-	framework_skip_ 'failed to create a symlink'
-
 run_prog > /dev/null
-run_strace -e $syscall -xx -s3 $args > "$OUT"
+run_strace -xx -e $syscall $args > "$OUT"
 match_diff "$LOG" "$OUT"
 
-rm -f -- "$OUT" $link
-
-exit 0
+rm -f -- "$OUT"

tests/readlinkat.c

@@ -34,32 +34,48 @@
 # include <stdio.h>
 # include <unistd.h>
 
+# define PREFIX "test.readlinkat"
+# define TARGET (PREFIX ".target")
+# define LINKPATH (PREFIX ".link")
+
 int
 main(void)
 {
-	static const char fname[] = "readlinkat.link";
-	unsigned char buf[31];
-	long rc;
-	unsigned int i;
+	const char * const fname = tail_memdup(LINKPATH, sizeof(LINKPATH));
+	const char * const hex_fname =
+		hexquote_strndup(fname, sizeof(LINKPATH) - 1);
+
+	const unsigned int size = sizeof(TARGET) - 1;
+	char * const buf = tail_alloc(size);
+
+	(void) unlink(fname);
+
+	long rc = syscall(__NR_readlinkat, -100, fname, buf, size);
+	printf("readlinkat(AT_FDCWD, \"%s\", %p, %u) = -1 ENOENT (%m)\n",
+	       hex_fname, buf, size);
+
+	if (symlink(TARGET, fname))
+		perror_msg_and_fail("symlink");
 
-	rc = syscall(__NR_readlinkat, -100, fname, buf, sizeof(buf));
-	if (rc < 0)
-		perror_msg_and_skip("readlinkat");
+	rc = syscall(__NR_readlinkat, -100, fname, buf, size);
+	if (rc < 0) {
+		perror("readlinkat");
+		(void) unlink(fname);
+		return 77;
+	}
+	const char * const hex_buf = hexquote_strndup(buf, size);
+	printf("readlinkat(AT_FDCWD, \"%s\", \"%s\", %u) = %u\n",
+	       hex_fname, hex_buf, size, size);
 
-	printf("readlinkat(AT_FDCWD, \"");
-	for (i = 0; fname[i]; ++i)
-		printf("\\x%02x", (int) (unsigned char) fname[i]);
-	printf("\", \"");
-	for (i = 0; i < 3; ++i)
-		printf("\\x%02x", (int) buf[i]);
-	printf("\"..., %zu) = %ld\n", sizeof(buf), rc);
+	if (unlink(fname))
+		perror_msg_and_fail("unlink");
 
 	puts("+++ exited with 0 +++");
 	return 0;
 }
 
 #else
 
-SKIP_MAIN_UNDEFINED("__NR_readlinkat")
+SKIP_MAIN_UNDEFINED("__NR_readlink")
 
 #endif