From 4cb474502c1325b2325ec642a520e1ed44eb317e Mon Sep 17 00:00:00 2001
From: Luke Shumaker <lukeshu@beefcake.parabola.nu>
Date: Wed, 16 May 2018 11:29:55 -0400
Subject: pretty-print the extent flags

---
 src/cow-extent-map.c | 92 +++++++++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 87 insertions(+), 5 deletions(-)

diff --git a/src/cow-extent-map.c b/src/cow-extent-map.c
index 7cee70c..1d9ae2c 100644
--- a/src/cow-extent-map.c
+++ b/src/cow-extent-map.c
@@ -5,9 +5,10 @@
 #include <fcntl.h>    /* for open(2) and O_RDONLY */
 #include <getopt.h>   /* for getopt_long(3gnu), struct option, optind, optarg */
 #include <inttypes.h> /* PRI* */
-#include <stdio.h>    /* for printf(3p), fprintf(3p), stderr */
-#include <stdlib.h>   /* exit(3p), EXIT_SUCCESS, EXIT_FAILURE */
-#include <string.h>   /* for strcmp(3p) */
+#include <stdbool.h>  /* for bool, true, false */
+#include <stdio.h>    /* for printf(3p), fprintf(3p), sprintf(3p), stderr */
+#include <stdlib.h>   /* malloc(3p), freep(3p), exit(3p), EXIT_SUCCESS, EXIT_FAILURE */
+#include <string.h>   /* for strcmp(3p), strlen(3p), strcpy(3p) */
 
 #include "extent-map.h" /* for uint32_t, fiemap stuff */ 
 
@@ -18,15 +19,96 @@
 	exit(EXIT_INVALIDARGUMENT); \
 } while(0)
 
+struct flag {
+	char *name;
+	uint32_t value;
+	bool active;
+};
+
 int print_extent(struct fiemap_extent extent) {
+	struct flag known_flags[] = {
+		{"LAST", FIEMAP_EXTENT_LAST, false},
+		{"UNKNOWN", FIEMAP_EXTENT_UNKNOWN, false},
+		{"DELALLOC", FIEMAP_EXTENT_DELALLOC, false},
+		{"ENCODED", FIEMAP_EXTENT_ENCODED, false},
+		{"DATA_ENCRYPTED", FIEMAP_EXTENT_DATA_ENCRYPTED, false},
+		{"NOT_ALIGNED", FIEMAP_EXTENT_NOT_ALIGNED, false},
+		{"DATA_INLINE", FIEMAP_EXTENT_DATA_INLINE, false},
+		{"DATA_TAIL", FIEMAP_EXTENT_DATA_TAIL, false},
+		{"UNWRITTEN", FIEMAP_EXTENT_UNWRITTEN, false},
+		{"MERGED", FIEMAP_EXTENT_MERGED, false},
+		{"SHARED", FIEMAP_EXTENT_SHARED, false},
+	};
+	uint32_t flags = extent.fe_flags;
+	size_t flagstr_cap = 0;
+	for (size_t i = 0; i < sizeof(known_flags)/sizeof(known_flags[0]); i++) {
+		if (!(flags & known_flags[i].value))
+			continue;
+		known_flags[i].active = true;
+		flags ^= known_flags[i].value;
+		switch (known_flags[i].value) {
+		case FIEMAP_EXTENT_UNKNOWN:
+			if (flags & FIEMAP_EXTENT_DELALLOC) {
+				known_flags[i].name = "(UNKNOWN|DELALLOC)";
+				flags ^= FIEMAP_EXTENT_DELALLOC;
+			}
+			break;
+		case FIEMAP_EXTENT_ENCODED:
+			if (flags & FIEMAP_EXTENT_DATA_ENCRYPTED) {
+				known_flags[i].name = "(ENCODED|DATA_ENCRYPTED)";
+				flags ^= FIEMAP_EXTENT_DATA_ENCRYPTED;
+			}
+			break;
+		case FIEMAP_EXTENT_NOT_ALIGNED:
+			switch (flags & (FIEMAP_EXTENT_DATA_INLINE|FIEMAP_EXTENT_DATA_TAIL)) {
+			case FIEMAP_EXTENT_DATA_INLINE:
+				known_flags[i].name = "(NOT_ALIGNED|DATA_INLINE)";
+				flags ^= FIEMAP_EXTENT_DATA_INLINE;
+				break;
+			case FIEMAP_EXTENT_DATA_TAIL:
+				known_flags[i].name = "(NOT_ALIGNED|DATA_TAIL)";
+				flags ^= FIEMAP_EXTENT_DATA_TAIL;
+				break;
+			case FIEMAP_EXTENT_DATA_INLINE|FIEMAP_EXTENT_DATA_TAIL:
+				known_flags[i].name = "(NOT_ALIGNED|DATA_INLINE|DATA_TAIL)";
+				flags ^= FIEMAP_EXTENT_DATA_INLINE|FIEMAP_EXTENT_DATA_TAIL;
+				break;
+			}
+			break;
+		}
+		if (flagstr_cap)
+			flagstr_cap++;
+		flagstr_cap += strlen(known_flags[i].name);
+	}
+	if (flags)
+		flagstr_cap += (flagstr_cap ? 1 : 0) + 10;
+	char *flagstr = malloc(flagstr_cap+1);
+	if (!flagstr)
+		error(EXIT_FAILURE, errno, "malloc");
+	size_t flagstr_len = 0;
+	for (size_t i = 0; i < sizeof(known_flags)/sizeof(known_flags[0]); i++) {
+		if (!known_flags[i].active)
+			continue;
+		if (flagstr_len)
+			flagstr[flagstr_len++] = '|';
+		strcpy(&flagstr[flagstr_len], known_flags[i].name);
+		flagstr_len += strlen(known_flags[i].name);
+	}
+	if (flags) {
+		if (flagstr_len)
+			flagstr[flagstr_len++] = '|';
+		sprintf(&flagstr[flagstr_len], "0x%08"PRIx32, flags);
+	};
 	printf("logical=%"PRIu64" "
 	       "physical=%"PRIu64" "
 	       "length=%"PRIu64" "
-	       "flags=0x%"PRIx32"\n",
+	       "flags=0x%08"PRIx32" (%s)\n",
 	       extent.fe_logical,
 	       extent.fe_physical,
 	       extent.fe_length,
-	       extent.fe_flags);
+	       extent.fe_flags,
+	       flagstr);
+	free(flagstr);
 	return 0;
 }
 
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