From: Karel Zak <kzak@redhat.com>
Date: Fri, 20 Nov 2020 10:21:41 +0000 (+0100)
Subject: lib/caputils: split to multiple functions, add test
X-Git-Tag: v2.37-rc1~276
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=966420219cde98e72dd518e4f0005cb0c090a00d;p=thirdparty%2Futil-linux.git

lib/caputils: split to multiple functions, add test

Let's split the code to make it possible to test separately bsearch as
well as procfs based cap_last_cap().

 $ ./test_caputils --last-by-bsearch
 last cap: 39
 $ ./test_caputils --last-by-procfs
 last cap: 39
 $ ./test_caputils --last
 last cap: 39

Signed-off-by: Karel Zak <kzak@redhat.com>
---

diff --git a/lib/Makemodule.am b/lib/Makemodule.am
index bf389db0e2..6db9aaf771 100644
--- a/lib/Makemodule.am
+++ b/lib/Makemodule.am
@@ -100,7 +100,8 @@ check_PROGRAMS += test_cpuset
 endif
 check_PROGRAMS += \
 	test_sysfs \
-	test_pager
+	test_pager \
+	test_caputils
 endif
 
 if HAVE_OPENAT
@@ -110,6 +111,10 @@ check_PROGRAMS += test_path
 endif
 endif
 
+test_caputils_SOURCES = lib/caputils.c
+test_caputils_CFLAGS = $(AM_CFLAGS) -DTEST_PROGRAM_CAPUTILS
+test_caputils_LDADD = $(LDADD) libcommon.la
+
 test_ttyutils_SOURCES = lib/ttyutils.c
 test_ttyutils_CFLAGS = $(AM_CFLAGS) -DTEST_PROGRAM_TTYUTILS
 test_ttyutils_LDADD = $(LDADD) libcommon.la
diff --git a/lib/caputils.c b/lib/caputils.c
index 669330c50b..13a376bfce 100644
--- a/lib/caputils.c
+++ b/lib/caputils.c
@@ -16,8 +16,11 @@
 
 #include <sys/prctl.h>
 #include <stdio.h>
+#include <stdlib.h>
 #include <limits.h>
+#include <errno.h>
 
+#include "c.h"
 #include "caputils.h"
 #include "procutils.h"
 #include "pathnames.h"
@@ -28,45 +31,88 @@ static int test_cap(unsigned int cap)
 	return prctl(PR_CAPBSET_READ, cap, 0, 0, 0) >= 0;
 }
 
+static int cap_last_by_bsearch(int *ret)
+{
+	/* starting with cap=INT_MAX means we always know
+	 * that cap1 is invalid after the first iteration */
+	int cap = INT_MAX;
+	unsigned int cap0 = 0, cap1 = INT_MAX;
+
+	while ((int)cap0 < cap) {
+		if (test_cap(cap))
+			cap0 = cap;
+		else
+			cap1 = cap;
+
+		cap = (cap0 + cap1) / 2U;
+	}
+
+	*ret = cap;
+	return 0;
+}
+
+static int cap_last_by_procfs(int *ret)
+{
+	FILE *f = fopen(_PATH_PROC_CAPLASTCAP, "r");
+	int rc = -EINVAL;
+
+	*ret = 0;
+
+	if (f && proc_is_procfs(fileno(f))) {
+		int cap;
+
+		/* we check if the cap after this one really isn't valid */
+		if (fscanf(f, "%d", &cap) == 1 &&
+		    cap < INT_MAX && !test_cap(cap + 1)) {
+
+			*ret = cap;
+			rc = 0;
+		}
+	}
+
+	if (f)
+		fclose(f);
+	return rc;
+}
+
 int cap_last_cap(void)
 {
 	static int cap = -1;
-	FILE *f;
 
 	if (cap != -1)
 		return cap;
+	if (cap_last_by_procfs(&cap) < 0)
+		cap_last_by_bsearch(&cap);
 
-	/* try to read value from kernel, check that the path is
-	 * indeed in a procfs mount */
-	f = fopen(_PATH_PROC_CAPLASTCAP, "r");
-	if (f) {
-		int matched = 0;
+	return cap;
+}
 
-		if (proc_is_procfs(fileno(f))) {
-			matched = fscanf(f, "%d", &cap);
-		}
-		fclose(f);
+#ifdef TEST_PROGRAM_CAPUTILS
+int main(int argc, char *argv[])
+{
+	int rc = 0, cap;
 
-		/* we check if the cap after this one really isn't valid */
-		if (matched == 1 && cap < INT_MAX && !test_cap(cap + 1))
-			return cap;
+	if (argc < 2) {
+		fprintf(stderr, "usage: %1$s --last-by-procfs\n"
+				"       %1$s --last-by-bsearch\n"
+				"       %1$s --last\n",
+				program_invocation_short_name);
+		return EXIT_FAILURE;
 	}
 
-	/* if it wasn't possible to read the file in /proc,
-	 * fall back to binary search over capabilities */
+	if (strcmp(argv[1], "--last-by-procfs") == 0) {
+		rc = cap_last_by_procfs(&cap);
+		if (rc == 0)
+			printf("last cap: %d\n", cap);
 
-	/* starting with cap=INT_MAX means we always know
-	 * that cap1 is invalid after the first iteration */
-	unsigned int cap0 = 0, cap1 = INT_MAX;
-	cap = INT_MAX;
-	while ((int)cap0 < cap) {
-		if (test_cap(cap)) {
-			cap0 = cap;
-		} else {
-			cap1 = cap;
-		}
-		cap = (cap0 + cap1) / 2U;
-	}
+	} else if (strcmp(argv[1], "--last-by-bsearch") == 0) {
+		rc = cap_last_by_bsearch(&cap);
+		if (rc == 0)
+			printf("last cap: %d\n", cap);
 
-	return cap;
+	} else if (strcmp(argv[1], "--last") == 0)
+		printf("last cap: %d\n", cap_last_cap());
+
+	return rc == 0 ? EXIT_SUCCESS : EXIT_FAILURE;
 }
+#endif