git: a689bfa4e25a - main - libdiff: Simplify truncation detection

The branch main has been updated by des:

URL: https://cgit.FreeBSD.org/src/commit/?id=a689bfa4e25af8307709dc12f75b0e02a65abf18

commit a689bfa4e25af8307709dc12f75b0e02a65abf18
Author:     Dag-Erling Smørgrav <des@FreeBSD.org>
AuthorDate: 2026-02-05 14:39:34 +0000
Commit:     Dag-Erling Smørgrav <des@FreeBSD.org>
CommitDate: 2026-02-05 14:39:34 +0000

    libdiff: Simplify truncation detection
    
    * Adjust the comment to reflect the fact that SIGBUS can occur not only
      if the file is truncated, but also if an I/O error occurs while paging
      in any part of it.
    
    * Instead of setting a flag, just return EIO.
    
    * Adjust the unit test accordingly.
    
    MFC after:      1 week
    Sponsored by:   Klara, Inc.
    Reviewed by:    thj, kevans
    Differential Revision:  https://reviews.freebsd.org/D55108
---
 contrib/libdiff/include/diff_main.h     |  1 -
 contrib/libdiff/lib/diff_atomize_text.c | 12 +++++++-----
 lib/libdiff/tests/libdiff_test.c        |  3 +--
 usr.bin/diff/diffreg_new.c              |  4 ----
 4 files changed, 8 insertions(+), 12 deletions(-)

diff --git a/contrib/libdiff/include/diff_main.h b/contrib/libdiff/include/diff_main.h
index 11700580db4b..04a6c6e748c9 100644
--- a/contrib/libdiff/include/diff_main.h
+++ b/contrib/libdiff/include/diff_main.h
@@ -118,7 +118,6 @@ struct diff_data {
 
 /* Flags set by file atomizer. */
 #define DIFF_ATOMIZER_FOUND_BINARY_DATA	0x00000001
-#define DIFF_ATOMIZER_FILE_TRUNCATED	0x00000002
 
 /* Flags set by caller of diff_main(). */
 #define DIFF_FLAG_IGNORE_WHITESPACE	0x00000001
diff --git a/contrib/libdiff/lib/diff_atomize_text.c b/contrib/libdiff/lib/diff_atomize_text.c
index d8a69733fc00..9ed611cce4b2 100644
--- a/contrib/libdiff/lib/diff_atomize_text.c
+++ b/contrib/libdiff/lib/diff_atomize_text.c
@@ -141,6 +141,7 @@ diff_data_atomize_text_lines_mmap(struct diff_data *d)
 	bool embedded_nul = false;
 	unsigned int array_size_estimate = d->len / 50;
 	unsigned int pow2 = 1;
+	int ret = DIFF_RC_OK;
 	while (array_size_estimate >>= 1)
 		pow2++;
 
@@ -152,13 +153,14 @@ diff_data_atomize_text_lines_mmap(struct diff_data *d)
 	sigaction(SIGBUS, &act, &oact);
 	if (sigsetjmp(diff_data_signal_env, 0) > 0) {
 		/*
-		 * The file was truncated while we were reading it.  Set
-		 * the end pointer to the beginning of the line we were
-		 * trying to read, adjust the file length, and set a flag.
+		 * The file was truncated while we were reading it, or an
+		 * I/O error occurred.  Set the end pointer to the
+		 * beginning of the line we were trying to read, adjust
+		 * the file length, and set the return value to an error.
 		 */
 		end = pos;
 		d->len = end - d->data;
-		d->atomizer_flags |= DIFF_ATOMIZER_FILE_TRUNCATED;
+		ret = EIO;
 	}
 	while (pos < end) {
 		const uint8_t *line_start = pos, *line_end = pos;
@@ -203,7 +205,7 @@ diff_data_atomize_text_lines_mmap(struct diff_data *d)
 	if (embedded_nul)
 		d->atomizer_flags |= DIFF_ATOMIZER_FOUND_BINARY_DATA;
 
-	return DIFF_RC_OK;
+	return ret;
 }
 
 static int
diff --git a/lib/libdiff/tests/libdiff_test.c b/lib/libdiff/tests/libdiff_test.c
index e82a36f3d38a..2a7c1b37e2c2 100644
--- a/lib/libdiff/tests/libdiff_test.c
+++ b/lib/libdiff/tests/libdiff_test.c
@@ -45,10 +45,9 @@ ATF_TC_BODY(diff_atomize_truncated, tc)
 	rewind(f);
 	ATF_REQUIRE(truncate(fn, size / 2) == 0);
 	ATF_REQUIRE((p = mmap(NULL, size, PROT_READ, MAP_PRIVATE, fileno(f), 0)) != MAP_FAILED);
-	ATF_REQUIRE(diff_atomize_file(&d, &cfg, f, p, size, 0) == 0);
+	ATF_REQUIRE(diff_atomize_file(&d, &cfg, f, p, size, 0) == EIO);
 	ATF_REQUIRE((size_t)d.len <= size / 2);
 	ATF_REQUIRE((size_t)d.len >= size / 2 - sizeof(line));
-	ATF_REQUIRE(d.atomizer_flags & DIFF_ATOMIZER_FILE_TRUNCATED);
 }
 ATF_TC_CLEANUP(diff_atomize_truncated, tc)
 {
diff --git a/usr.bin/diff/diffreg_new.c b/usr.bin/diff/diffreg_new.c
index d932764bb6da..f29e4ad8b9ed 100644
--- a/usr.bin/diff/diffreg_new.c
+++ b/usr.bin/diff/diffreg_new.c
@@ -223,14 +223,10 @@ diffreg_new(char *file1, char *file2, int flags, int capsicum)
 		rc = D_ERROR;
 		goto done;
 	}
-	if (left.atomizer_flags & DIFF_ATOMIZER_FILE_TRUNCATED)
-		warnx("%s truncated", file1);
 	if (diff_atomize_file(&right, cfg, f2, (uint8_t *)str2, st2.st_size, diff_flags)) {
 		rc = D_ERROR;
 		goto done;
 	}
-	if (right.atomizer_flags & DIFF_ATOMIZER_FILE_TRUNCATED)
-		warnx("%s truncated", file2);
 
 	result = diff_main(cfg, &left, &right);
 	if (result->rc != DIFF_RC_OK) {