libext2fs: add support for the SOURCE_DATE_EPOCH environment variable

Add SOURCE_DATE_EPOCH support as documented in [1].

[1] https://reproducible-builds.org/specs/source-date-epoch

Signed-off-by: Theodore Ts'o <tytso@mit.edu>

11 files changed, 45 insertions, 22 deletions

diff --git a/lib/ext2fs/bb_inode.c b/lib/ext2fs/bb_inode.c
index 927a4d41d..8b29e1c8d 100644
--- a/lib/ext2fs/bb_inode.c
+++ b/lib/ext2fs/bb_inode.c
@@ -20,7 +20,6 @@
 #include <unistd.h>
 #endif
 #include <fcntl.h>
-#include <time.h>
 #if HAVE_SYS_STAT_H
 #include <sys/stat.h>
 #endif
@@ -29,7 +28,7 @@
 #endif
 
 #include "ext2_fs.h"
-#include "ext2fs.h"
+#include "ext2fsP.h"
 
 struct set_badblock_record {
 	ext2_badblocks_iterate	bb_iter;
@@ -125,7 +124,7 @@ errcode_t ext2fs_update_bb_inode(ext2_filsys fs, ext2_badblocks_list bb_list)
 	if (retval)
 		goto cleanup;
 
-	now = fs->now ? fs->now : time(0);
+	now = ext2fsP_get_time(fs);
 	ext2fs_inode_xtime_set(&inode, i_atime, now);
 	if (!ext2fs_inode_xtime_get(&inode, i_ctime))
 		ext2fs_inode_xtime_set(&inode, i_ctime, now);
diff --git a/lib/ext2fs/closefs.c b/lib/ext2fs/closefs.c
index 42bda1fae..8e5bec03a 100644
--- a/lib/ext2fs/closefs.c
+++ b/lib/ext2fs/closefs.c
@@ -301,7 +301,7 @@ errcode_t ext2fs_flush2(ext2_filsys fs, int flags)
 	fs_state = fs->super->s_state;
 	feature_incompat = fs->super->s_feature_incompat;
 
-	ext2fs_set_tstamp(fs->super, s_wtime, fs->now ? fs->now : time(NULL));
+	ext2fs_set_tstamp(fs->super, s_wtime, ext2fsP_get_time(fs));
 	fs->super->s_block_group_nr = 0;
 
 	/*
diff --git a/lib/ext2fs/ext2fs.h b/lib/ext2fs/ext2fs.h
index f3d98f600..c2638b803 100644
--- a/lib/ext2fs/ext2fs.h
+++ b/lib/ext2fs/ext2fs.h
@@ -222,6 +222,11 @@ typedef struct ext2_file *ext2_file_t;
 #define EXT2_FLAG_IGNORE_SWAP_DIRENT	0x8000000
 
 /*
+ * Internal flags for use by the ext2fs library only
+ */
+#define EXT2_FLAG2_USE_FAKE_TIME	0x000000001
+
+/*
  * Special flag in the ext2 inode i_flag field that means that this is
  * a new inode.  (So that ext2_write_inode() can clear extra fields.)
  */
@@ -275,10 +280,11 @@ struct struct_ext2_filsys {
 	int				cluster_ratio_bits;
 	__u16				default_bitmap_type;
 	__u16				pad;
+	__u32				flags2;
 	/*
 	 * Reserved for future expansion
 	 */
-	__u32				reserved[5];
+	__u32				reserved[4];
 
 	/*
 	 * Reserved for the use of the calling application.
diff --git a/lib/ext2fs/ext2fsP.h b/lib/ext2fs/ext2fsP.h
index 06873847c..d1f2105e9 100644
--- a/lib/ext2fs/ext2fsP.h
+++ b/lib/ext2fs/ext2fsP.h
@@ -26,6 +26,13 @@ static inline int ext2fsP_is_disk_device(mode_t mode)
 #endif
 }
 
+static inline time_t ext2fsP_get_time(ext2_filsys fs)
+{
+	if (fs->now || (fs->flags2 & EXT2_FLAG2_USE_FAKE_TIME))
+		return fs->now;
+	return time(NULL);
+}
+
 /*
  * Badblocks list
  */
diff --git a/lib/ext2fs/ext_attr.c b/lib/ext2fs/ext_attr.c
index 349404639..b33bcce39 100644
--- a/lib/ext2fs/ext_attr.c
+++ b/lib/ext2fs/ext_attr.c
@@ -23,7 +23,7 @@
 #include "ext2_ext_attr.h"
 #include "ext4_acl.h"
 
-#include "ext2fs.h"
+#include "ext2fsP.h"
 
 static errcode_t read_ea_inode_hash(ext2_filsys fs, ext2_ino_t ino, __u32 *hash)
 {
@@ -1342,7 +1342,7 @@ static errcode_t xattr_inode_dec_ref(ext2_filsys fs, ext2_ino_t ino)
 		goto write_out;
 
 	inode.i_links_count = 0;
-	inode.i_dtime = fs->now ? fs->now : time(0);
+	inode.i_dtime = ext2fsP_get_time(fs);
 
 	ret = ext2fs_free_ext_attr(fs, ino, &inode);
 	if (ret)
diff --git a/lib/ext2fs/initialize.c b/lib/ext2fs/initialize.c
index 513bf5a7e..b9cfd1bb3 100644
--- a/lib/ext2fs/initialize.c
+++ b/lib/ext2fs/initialize.c
@@ -26,7 +26,7 @@
 #endif
 
 #include "ext2_fs.h"
-#include "ext2fs.h"
+#include "ext2fsP.h"
 
 #ifndef O_BINARY
 #define O_BINARY 0
@@ -125,9 +125,15 @@ errcode_t ext2fs_initialize(const char *name, int flags,
 	fs->flags |= EXT2_FLAG_SWAP_BYTES;
 #endif
 
-	time_env = ext2fs_safe_getenv("E2FSPROGS_FAKE_TIME");
-	if (time_env)
+	time_env = ext2fs_safe_getenv("SOURCE_DATE_EPOCH");
+	if (time_env) {
 		fs->now = strtoul(time_env, NULL, 0);
+		fs->flags2 |= EXT2_FLAG2_USE_FAKE_TIME;
+	} else {
+		time_env = ext2fs_safe_getenv("E2FSPROGS_FAKE_TIME");
+		if (time_env)
+			fs->now = strtoul(time_env, NULL, 0);
+	}
 
 	io_flags = IO_FLAG_RW;
 	if (flags & EXT2_FLAG_EXCLUSIVE)
@@ -218,8 +224,8 @@ errcode_t ext2fs_initialize(const char *name, int flags,
 	}
 
 	set_field(s_checkinterval, 0);
-	ext2fs_set_tstamp(super, s_mkfs_time, fs->now ? fs->now : time(NULL));
-	ext2fs_set_tstamp(super, s_lastcheck, fs->now ? fs->now : time(NULL));
+	ext2fs_set_tstamp(super, s_mkfs_time, ext2fsP_get_time(fs));
+	ext2fs_set_tstamp(super, s_lastcheck, ext2fsP_get_time(fs));
 
 	super->s_creator_os = CREATOR_OS;
 
diff --git a/lib/ext2fs/inode.c b/lib/ext2fs/inode.c
index 8686f99c6..c9389a232 100644
--- a/lib/ext2fs/inode.c
+++ b/lib/ext2fs/inode.c
@@ -1042,7 +1042,7 @@ errcode_t ext2fs_write_new_inode(ext2_filsys fs, ext2_ino_t ino,
 	int			size = EXT2_INODE_SIZE(fs->super);
 	struct ext2_inode_large	*large_inode;
 	errcode_t		retval;
-	time_t			t = fs->now ? fs->now : time(NULL);
+	time_t			t = ext2fsP_get_time(fs);
 
 	if (!ext2fs_inode_xtime_get(inode, i_atime))
 		ext2fs_inode_xtime_set(inode, i_atime, t);
diff --git a/lib/ext2fs/mkjournal.c b/lib/ext2fs/mkjournal.c
index 4a947b618..27cdfa05a 100644
--- a/lib/ext2fs/mkjournal.c
+++ b/lib/ext2fs/mkjournal.c
@@ -20,7 +20,6 @@
 #include <errno.h>
 #endif
 #include <fcntl.h>
-#include <time.h>
 #if HAVE_SYS_STAT_H
 #include <sys/stat.h>
 #endif
@@ -36,7 +35,7 @@
 
 #include "ext2_fs.h"
 #include "e2p/e2p.h"
-#include "ext2fs.h"
+#include "ext2fsP.h"
 
 #include "kernel-jbd.h"
 
@@ -313,7 +312,7 @@ static errcode_t write_journal_inode(ext2_filsys fs, ext2_ino_t journal_ino,
 
 	inode_size = (unsigned long long)fs->blocksize *
 			(jparams->num_journal_blocks + jparams->num_fc_blocks);
-	now = fs->now ? fs->now : time(0);
+	now = ext2fsP_get_time(fs);
 	ext2fs_inode_xtime_set(&inode, i_mtime, now);
 	ext2fs_inode_xtime_set(&inode, i_ctime, now);
 	inode.i_links_count = 1;
diff --git a/lib/ext2fs/openfs.c b/lib/ext2fs/openfs.c
index ed2f7c31f..2b8e0e753 100644
--- a/lib/ext2fs/openfs.c
+++ b/lib/ext2fs/openfs.c
@@ -149,9 +149,15 @@ errcode_t ext2fs_open2(const char *name, const char *io_options,
 	fs->flags |= EXT2_FLAG_MASTER_SB_ONLY;
 	fs->umask = 022;
 
-	time_env = ext2fs_safe_getenv("E2FSPROGS_FAKE_TIME");
-	if (time_env)
+	time_env = ext2fs_safe_getenv("SOURCE_DATE_EPOCH");
+	if (time_env) {
 		fs->now = strtoul(time_env, NULL, 0);
+		fs->flags2 |= EXT2_FLAG2_USE_FAKE_TIME;
+	} else {
+		time_env = ext2fs_safe_getenv("E2FSPROGS_FAKE_TIME");
+		if (time_env)
+			fs->now = strtoul(time_env, NULL, 0);
+	}
 
 	retval = ext2fs_get_mem(strlen(name)+1, &fs->device_name);
 	if (retval)
diff --git a/lib/ext2fs/orphan.c b/lib/ext2fs/orphan.c
index ed897418b..913eb9a03 100644
--- a/lib/ext2fs/orphan.c
+++ b/lib/ext2fs/orphan.c
@@ -185,7 +185,7 @@ errcode_t ext2fs_create_orphan_file(ext2_filsys fs, blk_t num_blocks)
 	if (err)
 		goto out;
 	ext2fs_iblk_set(fs, &inode, 0);
-	now = fs->now ? fs->now : time(0);
+	now = ext2fsP_get_time(fs);
 	ext2fs_inode_xtime_set(&inode, i_atime, now);
 	ext2fs_inode_xtime_set(&inode, i_ctime, now);
 	ext2fs_inode_xtime_set(&inode, i_mtime, now);
diff --git a/lib/ext2fs/res_gdt.c b/lib/ext2fs/res_gdt.c
index 8d2a08626..334964808 100644
--- a/lib/ext2fs/res_gdt.c
+++ b/lib/ext2fs/res_gdt.c
@@ -15,7 +15,7 @@
 #include <string.h>
 #include <time.h>
 #include "ext2_fs.h"
-#include "ext2fs.h"
+#include "ext2fsP.h"
 
 /*
  * Iterate through the groups which hold BACKUP superblock/GDT copies in an
@@ -143,7 +143,7 @@ errcode_t ext2fs_create_resize_inode(ext2_filsys fs)
 		retval = ext2fs_inode_size_set(fs, &inode, inode_size);
 		if (retval)
 			goto out_free;
-		inode.i_ctime = fs->now ? fs->now : time(0);
+		inode.i_ctime = ext2fsP_get_time(fs);
 	}
 
 	for (rsv_off = 0, gdt_off = fs->desc_blocks,
@@ -235,7 +235,7 @@ out_inode:
 	       EXT2_I_SIZE(&inode));
 #endif
 	if (inode_dirty) {
-		time_t now = fs->now ? fs->now : time(0);
+		time_t now = ext2fsP_get_time(fs);
 
 		ext2fs_inode_xtime_set(&inode, i_atime, now);
 		ext2fs_inode_xtime_set(&inode, i_mtime, now);