Add efi_time_t and time conversion and formatting utilities

This adds the hilariously defective efi_time_t type, as well as
conversion utilities to and from it, and utilities for formatted output
of it.

Optionally, for compatibility with older source trees, if your
application defines EFIVAR_NO_EFI_TIME_T to any value other than 0, it
will *not* do so, though that option may go away in some future efivar
version.  This allows you to turn off declaration of efi_time_t and
related functions in the case where it's declared someplace else, such
as in some local code or another library's headers.

Signed-off-by: Peter Jones <pjones@redhat.com>

src/Makefile

@@ -18,7 +18,7 @@ LIBEFIBOOT_SOURCES = crc32.c creator.c disk.c gpt.c loadopt.c path-helpers.c \
 LIBEFIBOOT_OBJECTS = $(patsubst %.c,%.o,$(LIBEFIBOOT_SOURCES))
 LIBEFIVAR_SOURCES = crc32.c dp.c dp-acpi.c dp-hw.c dp-media.c dp-message.c \
 	efivarfs.c error.c export.c guid.c guids.S guid-symbols.c \
-	lib.c vars.c
+	lib.c vars.c time.c
 LIBEFIVAR_OBJECTS = $(patsubst %.S,%.o,$(patsubst %.c,%.o,$(LIBEFIVAR_SOURCES)))
 EFIVAR_SOURCES = efivar.c
 EFIVAR_OBJECTS = $(patsubst %.S,%.o,$(patsubst %.c,%.o,$(EFIVAR_SOURCES)))

src/include/efivar/efivar-time.h

@@ -0,0 +1,33 @@
+// SPDX-License-Identifier: LGPL-2.1
+/*
+ * efivar-time.h
+ * Copyright 2020 Peter Jones <pjones@redhat.com>
+ */
+
+#if defined(EFIVAR_NO_EFI_TIME_T) && EFIVAR_NO_EFI_TIME_T && \
+    !defined(EFIVAR_TIME_H_)
+#define EFIVAR_TIME_H_ 1
+#endif
+
+#ifndef EFIVAR_TIME_H_
+#define EFIVAR_TIME_H_ 1
+
+#include <stdbool.h>
+
+extern int tm_to_efi_time(const struct tm *const s, efi_time_t *d, bool tzadj);
+extern int efi_time_to_tm(const efi_time_t * const s, struct tm *d);
+
+extern char *efi_asctime(const efi_time_t *const time);
+extern char *efi_asctime_r(const efi_time_t *const time, char *buf);
+extern efi_time_t *efi_gmtime(const time_t *time);
+extern efi_time_t *efi_gmtime_r(const time_t *time, efi_time_t *result);
+extern efi_time_t *efi_localtime(const time_t *time);
+extern efi_time_t *efi_localtime_r(const time_t *time, efi_time_t *result);
+extern time_t efi_mktime(const efi_time_t *const time);
+
+extern char *efi_strptime(const char *s, const char *format, efi_time_t *time);
+extern size_t efi_strftime(char *s, size_t max, const char *format,
+			   const efi_time_t *time);
+
+#endif /* !EFIVAR_TIME_H_ */
+// vim:fenc=utf-8:tw=75:noet

src/include/efivar/efivar-types.h

@@ -51,6 +51,41 @@ typedef uint16_t efi_char16_t;
 typedef unsigned long uintn_t;
 typedef long intn_t;
 
+#if !defined(EFIVAR_NO_EFI_TIME_T) || EFIVAR_NO_EFI_TIME_T
+#define EFIVAR_HAVE_EFI_TIME_T 1
+
+/*
+ * This can never be correct, as defined, in the face of leap seconds.
+ * Because seconds here are defined with a range of [0,59], we can't
+ * express leap seconds correctly there.  Because TimeZone is specified in
+ * minutes West of UTC, rather than seconds (like struct tm), it can't be
+ * used to correct when we cross a leap second boundary condition.  As a
+ * result, EFI_TIME can only express UT1, rather than UTC, and there's no
+ * way when converting to know wether the error has been taken into
+ * account, nor if it should be.
+ *
+ * As I write this, there is a 37 second error.
+ */
+typedef struct {
+	uint16_t	year;		// 1900 - 9999
+	uint8_t		month;		// 1 - 12
+	uint8_t		day;		// 1 - 31
+	uint8_t		hour;		// 0 - 23
+	uint8_t		minute;		// 0 - 59
+	uint8_t		second;		// 0 - 59 // ha ha only serious
+	uint8_t		pad1;		// 0
+	uint32_t	nanosecond;	// 0 - 999,999,999
+	int16_t		timezone;	// minutes from UTC or EFI_UNSPECIFIED_TIMEZONE
+	uint8_t		daylight;	// bitfield
+	uint8_t		pad2;		// 0
+} efi_time_t __attribute__((__aligned__(1)));
+
+#define EFI_TIME_ADJUST_DAYLIGHT        ((uint8_t)0x01)
+#define EFI_TIME_IN_DAYLIGHT            ((uint8_t)0x02)
+
+#define EFI_UNSPECIFIED_TIMEZONE        ((uint16_t)0x07ff)
+#endif /* !defined(EFIVAR_NO_EFI_TIME_T) || EFIVAR_NO_EFI_TIME_T */
+
 #define EFI_VARIABLE_NON_VOLATILE				((uint64_t)0x0000000000000001)
 #define EFI_VARIABLE_BOOTSERVICE_ACCESS				((uint64_t)0x0000000000000002)
 #define EFI_VARIABLE_RUNTIME_ACCESS				((uint64_t)0x0000000000000004)

src/include/efivar/efivar.h

@@ -14,6 +14,7 @@
 #include <stdio.h>
 #include <sys/stat.h>
 #include <sys/types.h>
+#include <time.h>
 #include <unistd.h>
 #include <byteswap.h>
 
@@ -200,6 +201,7 @@ extern uint32_t efi_get_libefivar_version(void)
 	__attribute__((__visibility__("default")));
 
 #include <efivar/efivar-dp.h>
+#include <efivar/efivar-time.h>
 
 #endif /* EFIVAR_H */
 

src/libefiboot.abixml

@@ -670,7 +670,7 @@
       <parameter type-id='type-id-89'/>
       <return type-id='type-id-89'/>
     </function-decl>
-    <function-decl name='efi_error_set' filepath='src/include/efivar/efivar.h' line='128' column='1' visibility='default' binding='global' size-in-bits='64'>
+    <function-decl name='efi_error_set' filepath='src/include/efivar/efivar.h' line='129' column='1' visibility='default' binding='global' size-in-bits='64'>
       <parameter type-id='type-id-98'/>
       <parameter type-id='type-id-98'/>
       <parameter type-id='type-id-15'/>
@@ -679,14 +679,14 @@
       <parameter is-variadic='yes'/>
       <return type-id='type-id-15'/>
     </function-decl>
-    <function-decl name='efi_error_clear' filepath='src/include/efivar/efivar.h' line='136' column='1' visibility='default' binding='global' size-in-bits='64'>
+    <function-decl name='efi_error_clear' filepath='src/include/efivar/efivar.h' line='137' column='1' visibility='default' binding='global' size-in-bits='64'>
       <return type-id='type-id-28'/>
     </function-decl>
-    <function-decl name='efi_set_loglevel' filepath='src/include/efivar/efivar.h' line='138' column='1' visibility='default' binding='global' size-in-bits='64'>
+    <function-decl name='efi_set_loglevel' filepath='src/include/efivar/efivar.h' line='139' column='1' visibility='default' binding='global' size-in-bits='64'>
       <parameter type-id='type-id-15'/>
       <return type-id='type-id-28'/>
     </function-decl>
-    <function-decl name='efi_get_logfile' filepath='src/include/efivar/efivar.h' line='196' column='1' visibility='default' binding='global' size-in-bits='64'>
+    <function-decl name='efi_get_logfile' filepath='src/include/efivar/efivar.h' line='197' column='1' visibility='default' binding='global' size-in-bits='64'>
       <return type-id='type-id-91'/>
     </function-decl>
     <function-decl name='device_get' filepath='src/linux.h' line='142' column='1' visibility='default' binding='global' size-in-bits='64'>
@@ -1082,7 +1082,7 @@
       <parameter type-id='type-id-122'/>
       <return type-id='type-id-89'/>
     </function-decl>
-    <function-decl name='efi_str_to_guid' filepath='src/include/efivar/efivar.h' line='56' column='1' visibility='default' binding='global' size-in-bits='64'>
+    <function-decl name='efi_str_to_guid' filepath='src/include/efivar/efivar.h' line='57' column='1' visibility='default' binding='global' size-in-bits='64'>
       <parameter type-id='type-id-98'/>
       <parameter type-id='type-id-122'/>
       <return type-id='type-id-15'/>
@@ -1191,7 +1191,7 @@
       <parameter type-id='type-id-89'/>
       <return type-id='type-id-89'/>
     </function-decl>
-    <function-decl name='efi_error_pop' filepath='src/include/efivar/efivar.h' line='137' column='1' visibility='default' binding='global' size-in-bits='64'>
+    <function-decl name='efi_error_pop' filepath='src/include/efivar/efivar.h' line='138' column='1' visibility='default' binding='global' size-in-bits='64'>
       <return type-id='type-id-28'/>
     </function-decl>
     <function-decl name='find_path_segment' filepath='src/path-helpers.h' line='12' column='1' visibility='default' binding='global' size-in-bits='64'>
@@ -2240,7 +2240,7 @@
     <pointer-type-def type-id='type-id-32' size-in-bits='64' id='type-id-281'/>
     <pointer-type-def type-id='type-id-24' size-in-bits='64' id='type-id-138'/>
     <pointer-type-def type-id='type-id-138' size-in-bits='64' id='type-id-282'/>
-    <function-decl name='efi_get_verbose' filepath='src/include/efivar/efivar.h' line='194' column='1' visibility='default' binding='global' size-in-bits='64'>
+    <function-decl name='efi_get_verbose' filepath='src/include/efivar/efivar.h' line='195' column='1' visibility='default' binding='global' size-in-bits='64'>
       <return type-id='type-id-15'/>
     </function-decl>
     <function-decl name='efi_loadopt_create' mangled-name='efi_loadopt_create' filepath='src/loadopt.c' line='26' column='1' visibility='default' binding='global' size-in-bits='64' elf-symbol-id='efi_loadopt_create@@libefiboot.so.0'>