svn commit: r365945 - in head: share/man/man9 sys/kern sys/sys
Mitchell Horne
mhorne at FreeBSD.org
Mon Sep 21 15:24:46 UTC 2020
Author: mhorne
Date: Mon Sep 21 15:24:44 2020
New Revision: 365945
URL: https://svnweb.freebsd.org/changeset/base/365945
Log:
Add getenv(9) boolean parsing functions
This adds the getenv_bool() function, to parse a boolean value from a
kernel environment variable or tunable. This works for traditional
boolean values like "0" and "1", and also "true" and "false"
(case-insensitive). These semantics do not yet apply to sysctls declared
using SYSCTL_BOOL with CTLFLAG_TUN (they still only parse 1 and 0).
Also added are two wrapper functions, getenv_is_true() and
getenv_is_false(). These are slightly simpler for callers wishing to
perform a single check of a configuration variable.
Reviewed by: jhb (slightly earlier version)
Sponsored by: NetApp, Inc.
Sponsored by: Klara, Inc.
Differential Revision: https://reviews.freebsd.org/D26270
Modified:
head/share/man/man9/Makefile
head/share/man/man9/getenv.9
head/sys/kern/kern_environment.c
head/sys/sys/kernel.h
head/sys/sys/systm.h
Modified: head/share/man/man9/Makefile
==============================================================================
--- head/share/man/man9/Makefile Mon Sep 21 12:37:41 2020 (r365944)
+++ head/share/man/man9/Makefile Mon Sep 21 15:24:44 2020 (r365945)
@@ -1092,6 +1092,9 @@ MLINKS+=getenv.9 freeenv.9 \
getenv.9 getenv_quad.9 \
getenv.9 getenv_uint.9 \
getenv.9 getenv_ulong.9 \
+ getenv.9 getenv_bool.9 \
+ getenv.9 getenv_is_true.9 \
+ getenv.9 getenv_is_false.9 \
getenv.9 kern_getenv.9 \
getenv.9 kern_setenv.9 \
getenv.9 kern_unsetenv.9 \
Modified: head/share/man/man9/getenv.9
==============================================================================
--- head/share/man/man9/getenv.9 Mon Sep 21 12:37:41 2020 (r365944)
+++ head/share/man/man9/getenv.9 Mon Sep 21 15:24:44 2020 (r365945)
@@ -27,7 +27,7 @@
.\"
.\" $FreeBSD$
.\"
-.Dd June 1, 2017
+.Dd September 21, 2020
.Dt GETENV 9
.Os
.Sh NAME
@@ -39,6 +39,9 @@
.Nm getenv_quad ,
.Nm getenv_uint ,
.Nm getenv_ulong ,
+.Nm getenv_bool ,
+.Nm getenv_is_true ,
+.Nm getenv_is_false ,
.Nm kern_setenv ,
.Nm testenv ,
.Nm kern_unsetenv
@@ -63,6 +66,12 @@
.Ft int
.Fn getenv_ulong "const char *name" "unsigned long *data"
.Ft int
+.Fn getenv_bool "const char *name" "bool *data"
+.Ft bool
+.Fn getenv_is_true "const char *name"
+.Ft bool
+.Fn getenv_is_false "const char *name"
+.Ft int
.Fn kern_setenv "const char *name" "const char *value"
.Ft int
.Fn testenv "const char *name"
@@ -194,6 +203,28 @@ up to
characters of its value are copied to the buffer pointed to by
.Fa data
followed by a null character and a non-zero value is returned.
+.Pp
+The
+.Fn getenv_bool
+function interprets the value of the kernel environment variable
+.Fa name
+as a boolean value by performing a case-insensitive comparison against the
+strings "1",
+"0",
+"true",
+and "false".
+If the environment variable exists and has a valid boolean value, then that
+value will be copied to the variable pointed to by
+.Fa data .
+If the environment variable exists but is not a boolean value, then a warning
+will be printed to the kernel message buffer.
+The
+.Fn getenv_is_true
+and
+.Fn getenv_is_false
+functions are wrappers around
+.Fn getenv_bool
+that simplify testing for a desired boolean value.
.Sh RETURN VALUES
The
.Fn kern_getenv
@@ -211,12 +242,25 @@ The
.Fn testenv
function returns zero if the specified environment variable does not exist and
a non-zero value if it does exist.
+.Pp
The
.Fn getenv_int ,
.Fn getenv_long ,
.Fn getenv_string ,
.Fn getenv_quad ,
.Fn getenv_uint ,
+.Fn getenv_ulong ,
and
-.Fn getenv_ulong
+.Fn getenv_bool
functions return a non-zero value on success and zero on failure.
+.Pp
+The
+.Fn getenv_is_true
+and
+.Fn getenv_is_false
+functions return
+.Dv true
+if the specified environment variable exists and its value matches the desired
+boolean condition, and
+.Dv false
+otherwise.
Modified: head/sys/kern/kern_environment.c
==============================================================================
--- head/sys/kern/kern_environment.c Mon Sep 21 12:37:41 2020 (r365944)
+++ head/sys/kern/kern_environment.c Mon Sep 21 15:24:44 2020 (r365945)
@@ -942,6 +942,65 @@ error:
}
/*
+ * Return a boolean value from an environment variable. This can be in
+ * numerical or string form, i.e. "1" or "true".
+ */
+int
+getenv_bool(const char *name, bool *data)
+{
+ char *val;
+ int ret = 0;
+
+ if (name == NULL)
+ return (0);
+
+ val = kern_getenv(name);
+ if (val == NULL)
+ return (0);
+
+ if ((strcmp(val, "1") == 0) || (strcasecmp(val, "true") == 0)) {
+ *data = true;
+ ret = 1;
+ } else if ((strcmp(val, "0") == 0) || (strcasecmp(val, "false") == 0)) {
+ *data = false;
+ ret = 1;
+ } else {
+ /* Spit out a warning for malformed boolean variables. */
+ printf("Environment variable %s has non-boolean value \"%s\"\n",
+ name, val);
+ }
+ freeenv(val);
+
+ return (ret);
+}
+
+/*
+ * Wrapper around getenv_bool to easily check for true.
+ */
+bool
+getenv_is_true(const char *name)
+{
+ bool val;
+
+ if (getenv_bool(name, &val) != 0)
+ return (val);
+ return (false);
+}
+
+/*
+ * Wrapper around getenv_bool to easily check for false.
+ */
+bool
+getenv_is_false(const char *name)
+{
+ bool val;
+
+ if (getenv_bool(name, &val) != 0)
+ return (!val);
+ return (false);
+}
+
+/*
* Find the next entry after the one which (cp) falls within, return a
* pointer to its start or NULL if there are no more.
*/
@@ -1005,6 +1064,14 @@ tunable_quad_init(void *data)
struct tunable_quad *d = (struct tunable_quad *)data;
TUNABLE_QUAD_FETCH(d->path, d->var);
+}
+
+void
+tunable_bool_init(void *data)
+{
+ struct tunable_bool *d = (struct tunable_bool *)data;
+
+ TUNABLE_BOOL_FETCH(d->path, d->var);
}
void
Modified: head/sys/sys/kernel.h
==============================================================================
--- head/sys/sys/kernel.h Mon Sep 21 12:37:41 2020 (r365944)
+++ head/sys/sys/kernel.h Mon Sep 21 15:24:44 2020 (r365945)
@@ -421,6 +421,25 @@ struct tunable_quad {
#define TUNABLE_QUAD_FETCH(path, var) getenv_quad((path), (var))
+/*
+ * bool
+ */
+extern void tunable_bool_init(void *);
+struct tunable_bool {
+ const char *path;
+ bool *var;
+};
+#define TUNABLE_BOOL(path, var) \
+ static struct tunable_bool __CONCAT(__tunable_bool_, __LINE__) = { \
+ (path), \
+ (var), \
+ }; \
+ SYSINIT(__CONCAT(__Tunable_init_, __LINE__), \
+ SI_SUB_TUNABLES, SI_ORDER_MIDDLE, tunable_bool_init, \
+ &__CONCAT(__tunable_bool_, __LINE__))
+
+#define TUNABLE_BOOL_FETCH(path, var) getenv_bool((path), (var))
+
extern void tunable_str_init(void *);
struct tunable_str {
const char *path;
Modified: head/sys/sys/systm.h
==============================================================================
--- head/sys/sys/systm.h Mon Sep 21 12:37:41 2020 (r365944)
+++ head/sys/sys/systm.h Mon Sep 21 15:24:44 2020 (r365945)
@@ -461,6 +461,9 @@ int getenv_string(const char *name, char *data, int si
int getenv_int64(const char *name, int64_t *data);
int getenv_uint64(const char *name, uint64_t *data);
int getenv_quad(const char *name, quad_t *data);
+int getenv_bool(const char *name, bool *data);
+bool getenv_is_true(const char *name);
+bool getenv_is_false(const char *name);
int kern_setenv(const char *name, const char *value);
int kern_unsetenv(const char *name);
int testenv(const char *name);
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