From 9b50adaaaa4fedc8bda6fcf32595ecf7a682fa8b Mon Sep 17 00:00:00 2001
From: Tavian Barnes <tavianator@tavianator.com>
Date: Tue, 19 Oct 2021 12:24:22 -0400
Subject: parse: Switch back to O_TRUNC from explicit ftruncate()

O_TRUNC is not equivalent to an unconditional ftruncate(), e.g. for
device files.

This reverts the behaviour change from 78944c81, which was never
released and is not supported in other find implementations.
---
 parse.c  | 23 +++++++----------------
 tests.sh | 24 +++++++++---------------
 2 files changed, 16 insertions(+), 31 deletions(-)

diff --git a/parse.c b/parse.c
index c257f4e..aea7b4f 100644
--- a/parse.c
+++ b/parse.c
@@ -336,9 +336,8 @@ static int expr_open(struct parser_state *state, struct expr *expr, const char *
 
 	FILE *file = NULL;
 	CFILE *cfile = NULL;
-	CFILE *dedup = NULL;
 
-	file = xfopen(path, O_WRONLY | O_CREAT | O_CLOEXEC);
+	file = xfopen(path, O_WRONLY | O_CREAT | O_TRUNC | O_CLOEXEC);
 	if (!file) {
 		goto fail;
 	}
@@ -348,18 +347,12 @@ static int expr_open(struct parser_state *state, struct expr *expr, const char *
 		goto fail;
 	}
 
-	dedup = bfs_ctx_dedup(ctx, cfile, path);
+	CFILE *dedup = bfs_ctx_dedup(ctx, cfile, path);
 	if (!dedup) {
 		goto fail;
 	}
 
-	if (dedup == cfile) {
-		// O_TRUNC was omitted above to avoid repeatedly truncating the same file, so do it
-		// manually here
-		if (ftruncate(fileno(file), 0) != 0) {
-			goto fail;
-		}
-	} else {
+	if (dedup != cfile) {
 		cfclose(cfile);
 	}
 
@@ -368,12 +361,10 @@ static int expr_open(struct parser_state *state, struct expr *expr, const char *
 
 fail:
 	parse_error(state, "${blu}%s${rs} ${bld}%s${rs}: %m.\n", expr->argv[0], path);
-	if (!dedup) {
-		if (cfile) {
-			cfclose(cfile);
-		} else if (file) {
-			fclose(file);
-		}
+	if (cfile) {
+		cfclose(cfile);
+	} else if (file) {
+		fclose(file);
 	}
 	return -1;
 }
diff --git a/tests.sh b/tests.sh
index 2580d2f..c488aec 100755
--- a/tests.sh
+++ b/tests.sh
@@ -524,6 +524,7 @@ gnu_tests=(
     test_fprint
     test_fprint_duplicate
     test_fprint_error
+    test_fprint_noerror
     test_fprint_noarg
     test_fprint_nonexistent
     test_fprint_truncate
@@ -736,7 +737,6 @@ bfs_tests=(
 
     test_execdir_plus
 
-    test_fprint_append
     test_fprint_duplicate_stdout
     test_fprint_error_stdout
     test_fprint_error_stderr
@@ -1796,20 +1796,6 @@ function test_fprint_truncate() {
     fi
 }
 
-function test_fprint_append() {
-    rm -f scratch/test_fprint_append.out
-
-    invoke_bfs basic -fprint scratch/test_fprint_append.out >>scratch/test_fprint_append.out
-    invoke_bfs basic -fprint scratch/test_fprint_append.out >>scratch/test_fprint_append.out
-    sort -o scratch/test_fprint_append.out scratch/test_fprint_append.out
-
-    if [ "$UPDATE" ]; then
-        cp {scratch,"$TESTS"}/test_fprint_append.out
-    else
-        diff -u {"$TESTS",scratch}/test_fprint_append.out
-    fi
-}
-
 function test_double_dash() {
     cd basic
     bfs_diff -- . -type f
@@ -2724,6 +2710,14 @@ function test_fprint_error() {
     fi
 }
 
+function test_fprint_noerror() {
+    # Regression test: /dev/full should not fail until actually written to
+
+    if [ -e /dev/full ]; then
+        invoke_bfs basic -false -fprint /dev/full
+    fi
+}
+
 function test_fprint_error_stdout() {
     if [ -e /dev/full ]; then
         fail quiet invoke_bfs basic -maxdepth 0 -fprint /dev/full >/dev/full
-- 
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